CA2251649A1 - Methods and apparatus for eyeglass lens curing using ultraviolet light and improved cooling - Google Patents

Abstract

Method and apparatus for making and coating a plastic lens. Oxygen barrier containing photoinitiator is used to cure incompletely cured lens portions.
Radiation pulses are used to control lens curing rate. Lens is postcured while in a mold cavity using a conductive heat source. Air may be directed toward the mold cavity to help remove heat from the lens. An in-mold scratch resistant coating may be formed from two separate material which both contain a photoinitiator.

Description

CA 022~1649 1998-10-13 WO 97139880 PCTrUS97/06641 TITLE: METHODS AND APPARATUS FOR EYEGLASS LENS CURING USING
ULTRAVIOLET LIGHT AND IMPROVED COOLIN~

BACKGROUND OF THE INVENTION

I . Field of the Invention The present invention relates generally to methods and apparatus for making plastic lenses using ultraviolet light.

2. Description of Related Art It is conventional in the art to produce optical lenses by thermal curing techniques from the polymer of diethylene glycol bis(allyl)--,a,l,u,.ale (DEG-BAC). In addition, optical lenses may also be made using ultraviolet ("UV") light curing ~Prhni~lu~c See, for example, U.S. Patent Nos. 4,728,469 to Lipscomb et al., 4,879,318 to Lipscomb et al., 5,364,256 to l.ipscomh et al., 5,415,816 to Buazza et al., 5,529,728 to Buazza et al., 5,514,214 to 20 Joel et al., and U.S. patent application serial nos. 07/425,371 filed October 26, 1989, 08/454,523 filed May 30, 1995, 08/453,770 filed May 30, 1995, 07/932,812 filed August 18, 1992, 08/636,510 filed April 19, 1996, all of which are hereby specifically incc,,,uu,al~,d hereby by reference.

Curing of a lens by ultraviolet light tends to present certain problems that must be overcome to produce a 25 viable lens. Such problems include yellowing of the lens, cracking of the lens or mold, optical distortions in the lens, and premature release of the lens from the mold. In addition~ many of the useful UV-curable lens forming cu~ Jo~ ons exhibit certain ch~lla-,lelialics which increase the difficulty of a lens curing process. For example, due to the relatively rapid nature of ultraviolet light initiated reactions. it is a challenge to provide a composition which is UV curable to form an eyeglass lens. Excessive exothermic heat tends to cause defects in the cured lens.
30 To avoid such defects. the level of photoinitiator may be reduced to levels below what is customarily employed in the ultraviolet curing art.

While reducing the level of photoinitiator addresses some problems, it may also cause others. For instance, lowered levels of photoinitiator may eause the material in regions near an edge of the lens and 1~ l~e 35 a gasket wall in a mold cavity to incul.lpl~,lely cure due to the presence of oxygen in these regions (oxygen is believed to inhibit curing of many lens forming culllllosilinnc or materials). Uncured lens forming co-"~o~ilion tends to result in lenses with "wet" edges covered by sticky uncured lens forming co-..poailion. Furthermore, uncured lens formin_ co...~,u~ilion may migrate to and cont~in~t~ the optical surfaces of the lens upon demolding. The contaminated lens is then often unusable.

CA 022~1649 1998-10-13 W O 97t39880 PCTrUS97/06641 Uncured lens forming conlposiIiou has been addressed by a variet,v of methods (see. e.g., the methods described in U.S. Patent No.5,529,728 to Buazza et al). Such methods may include removing the gasket and applying either an oxygen barrier or a photoinitiator enriched liquid to the exposed edge of the lens, and then re-hlaJidtillg the lens with a dosage of ultraviolet light sufficient to completely dry the edge of the lens prior to demolding. During such irradiation, however, higher than desirable levels of irradiation, or longer than desirable periods of irradiation, may be required. The additional ultraviolet irradiation may in some ~h~ -lces cause defects such as yellowing in the lens.

The low photoinitiator levels utilized in many ultraviolet curable lens forming compositions may 10 produce a lens which, while fully-cured as measured by percentage of remaining double bonds~ may not possess ,-~rrk~: ~" crosslink density on the lens surface to provide desirable dye absorption ch."~ Iics during the tinting process.

Various methods of increasing the surface densitv of such UV curable lenses aredescribed in U.S. Patent 15 No. 5,529,728 to Buazza et al. In one method, the lens is demolded and then the surfaces of the lens are exposed directly to ultraviolet light. The relatively short wavelengths (around 254 nm) provided by some UV sources (e.g., a mercury vapor lamp) tend to cause the material to crosslink quite rapidly. An undesirable effect of this method, however, is that the lens tends to yellow as a result of such exposure.

Another method involves exposing the lens to relatively short wavelengths while it is still within a mold cavity formed between glass molds. The glass molds tend to absorb the more effective short wavelengths, while tr ~cnlitting wavelengths of about 365 nm. This method generally requires long exposure times and often the infrared radiation absorbed by the lens mold assembly will cause premature release of the lens from a mold member. The lens mold assembly may be heated prior to exposure to high intensity ultraviolet light, thereby 25 reducing the amount of radiation necessary to attain a desired level of crosslink density. This method, however, is also ~csoci~t~d with a higher rate of premature release.

It is well known in the art that a lens mold/gasket assembly may be heated to cure the lens forming c~ .po ,;1 ion from a liquid monomer to a solid polymer. It is also well known that such a lens may be thermally 30 postcured by applying convective heat to the lens after the molds and gaskets have been removed from the lens.

In this application the terms "lens forming material" and "lens forming co..~osilions" are used interchangeably .

CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 SUM MARY OFTHEINVENTION

One aspect of the invention relates to applying an oxygen barrier around the exposed edges of a lens to initiate the reaction of incompletely cured lens forming material plOXillla~e the lens edges. In an embodiment, a S liquid polymerizable lens forrning cul.,poailion is placed in a mold cavitv having at least two molds and/or a gasket. Ultraviolet rays may be directed toward at least one of the mold members to suhctAntiAlly cure the lens forming co~ o~;l;s"l to a lens having material proximate the edges of the lens that is not fully cured. The gasket may be removed to expose the edges of the lens, and an oxygen barrier COIll~ll iai-~g a photoinitiator may be placed around the exposed edges of the lens such that at least a portion of the oxygen barrier photoinitiator is proximate 10 lens forming c..~..j.G~ n that is not fully cured. A portion of the incompletely cured material may be removed manually prior to the application of the oxygen barrier. S--hseguently another set of ultraviolet rays may be directed towards the lens such that at least a portion of the oxygen barrier photoinitiator initiates reaction of lens forming c-,-llpoailion while the oxygen barrier sl~bctAnti~lly prevents oxygen from outside the oxygen barrier from cnnt~tin~ at least a portion of the lens forming co..,posiIion. The lens may be allowed to cool and the 15 oxygen barrier may be removed. The lens may be tinted after the cure is completed.

The oxygen barrier may include a flexible, stretchable, self-sealing film that is at least partially llalla~ I to ultraviolet rays. The oxygen barrier may include polyethylene i..l~ -laIed with a photoinitiator.
The film may include a strip of high density polyethylene that is about 0.01-1.0 mm thick. and more preferably 20 about 0.01-0.10 mm thick. Thicker films tend to be less conformable and stretchable. The oxygen barrier may include a plastic film that is less than about 0.025 mm thick. (e.g., about 0.0127 mm thick) and that was made by (a) immersing or running a plastic film in or through a solution COIllyl i~hlg a photoinitiator and an etching agent (b) removing the plastic film from the solution, and (c) drying the plastic film. A surface on the plastic film may be chemically etched prior to or while immersing the plastic film in the solution.
Another aspect of the invention relates to applying conductive heat to the face of a lens. In an embodiment of the invention, a liquid polylllcl i~ablc lens forming composition is placed in a mold cavity having a first mold member and a second mold member. First ultraviolet rays may be directed toward at least one of the mold members to cure the lens forming co..l~,oailion to a lens. A mold member may be applied to a ~ lly 30 solid conductive heat source. Heat may be conductively applied to a face of the lens by (a) conductively llallSl~l-...g heat to a face of a mold member from the conductive heat source, and (b) conductively l.allsrt,li..g heat through such mold member to the face of the lens.

In an c~.. ho~l;.. IL, a flexible heat di~L~ib~llul may be placed between the heat source and the mold 35 member to partially insulate the mold member and to slowly and uniformly transfer heat to the face of the mold member. The .li~I.il,.lIul may be shaped to conform to the face of a mold member. The heat source may include a concave element that may conform to the convex face of a mold member. The heat source may include a convex element that may conform to the concave face of a mold member. The t. .ll~. ~aIule of the heat source may be thermostatically controlled. Heat may be conductively applied through a mold member to the back face CA 022~1649 1998-10-13 of the lens, thereby ~nh Inci~lg the cross-linking and tintability of the lens forming material proximate to the surface of the back face of the lens (e.g., when an untintable scratch resistant coating is on the front face of the lens).

S In an c.. bod.ll,.,.lt of the invention an eyeglass lens may be formed by (a) placing a liquid, poly...~ able lens-forming u)lll~oailion in a mold cavity defined by at least a first mold member and a second mold member, (b) applying a plurality of preferably high intensity ultraviolet light pulses to the lens forming comrositiQn, at least one of the pulses having a duration of less than about one second (more preferably less than about 0.1 seconds, and more ~,.crclably between 0.1 and 0.001 seconds), and (c) curing the lens folTning 10 comrocition to forrn a ~ y clear eyeglass lens in a time period of less than 30 minutes (more preferably less than 20 minutes, and more preferably still less than 15 minutes).

The pulses preferably have a sufficiently high intensity such that reaction is initiated in substPrti:~lly all of the lens forming composition that is exposed to pulses in the mold cavity. In one embodiment reaction is 15 initiated in aubaI~Illially all of any cross section of the lens forming cor..pos;~ion that is exposed to pulses in the mold cavity. Preferably the temperature begins to rise after such application of UV light.

The lens forming c~ po,;~ may be exposed to UV light from one, two, or multiple sources. Two sources may be applied on opposite sides of the mold cavity to apply light to the lens forming composition from 20 two sides. In an alternate embodiment, the lens forming coll,posiIion is exposed to a relatively low intensity ultraviolet light before or while the pulses are applied. Such pulses are preferably relatively high in intensity, and are preferably applied to the other side of the mold cavity than the relatively low intensity light.

The lens forming cul-l?oa;Iion is preferably exposed to a relatively low intensity ultraviolet light while 25 the pulses are applied, the relatively iow intensity light having an intensity of less than 0.01 watt/ cm~ (and more preferably less than 0.001 watt/ cm2, and more preferably still 2-30 milliwatts/ cm~), as measured on an outside surface of a mold member of the mold cavity. The relatively low intensity light tends to provide a low amount of light to keep the reaction going in a more steady or even manner between pulses.
P~cr~.ably at least one or even all of the pulses has an intensity of at least .01 watt/ cm2, as ~-.c.,su-cd on an outside surface of a mold member of the mold cavity. Alternately at least one or even all of the pulses have an intensity of at least 0.1 or I watt/ cm2.

Sufficient ultraviolet light can be applied such that the tc.~ ,.aIulc of the lens forming co...~o~iIion 35 begins to increase. Then in one embo~l:~ent at least 5 minutes of waiting or darkness occurs before applying a~ ;u~l light (e.g., pulses). The waiting or darkness allows heat to dissipate, thus tending to prevent excessive heat buildup in the mold cavity. In one embodiment at least 5, 10, or 20 pulses are applied to the lens forming cornpooi~ion before waiting for about 5-8 minutes and then additional light is applied.

CA 022~1649 1998-10-13 The eyeglass lens has an average thickness of at least about 1.5-2.0 mm. Thicker lenses tend to be more difficult to cure with continl~ollc non-pulsed light.

The mold cavity is preferably cooled with air or cooled air. One cignifi~nt advantage of light pulses is 5 that ambient air may be used to cool the mold cavity, instead of cooled air. Thus signifi~nt lens curing costs may be avoided since air coolers tend to be costly to purchase and operate.
-The pulses preferably emanate from a flash source of light (i.e., "a flash light") such as a xenon lightsource. Preferably pulses are applied such that the lens forming composit ion is ov."~aluld1cd with ultraviolet 10 light during at least one pulse. Flash lights are advantageous in that they have a short "warm-up" time (as opposed to continuous lights that tend to require 5-60 minutes to stabilize).

Lenses may be formed with pulsed light that have more difficult to case prescriptions such as lenses with a power greater than positive 2 diopters, or lenses with a power less than minus 4 diopters.
One advantage of pulsed light application via flash lights is that even though higher int~nciti~S of light are applied, because the duration of the pulses is so short the total amount of light energy applied to cure the lens forming co,.,posilion is lessened. Thus less radiant heat is applied to the mold cavity, thereby reducing cooling Uil~,lllL.~I~a~ Moreover, energy is saved. In one embodiment less than 20, 10, 5, or I Joule/ cm- of energy is 20 applied to cure the lens forming composition into a lens.

Preferably the ultraviolet light is applied as a function of the temperature of the lens forming composition, as measured directly or indirectly by measuring a t~ "a1ulc within the chamber (e.g., a Ic~ ."a~ul~i of at least a portion of the mold cavity) or by measuring a temperature of air in or exiting the 25 chamber.

In another embodiment of the invention, an eyeglass lens may be cured by (a) placing a liquid, polymerizable lens forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming composition cUllllJI;aillg a photoinitiator, (b) applying ultraviolet light at an 30 intensity to the lens forming co..-poai~ion through at least one of the mold members for a selected period of time such that a l~ dUII~; of the cul~lpoai~ion begins to increase, (c) de~,-tàsi-.g the intensity of the ultraviolet light to inhibit the t~ ,.dlU~c of the lens forming composition from increasing to a selected first ~ ,.alulc, (d) allowing an exothermic reaction of the lens forming cullll,osi1ion to increase the 1~,.--p~,. d1UI c of the lens forming comrocition to a second t~ a~ulc, the second t~ d1U~ being less than the selected first temperature, (e) 35 curing the lens forrning cull.~oailion to form a 5--h5t~nti ~lly clear eyeglass lens by. (i) applying ultraviolet light at an intensity to the lens forming cu...po~ilion through at least one of the mold members, and (ii) decreasing the intensity of the ultraviolet light; and (f) wherein the eyeglass lens is formed from the lens forming composition in a time period of less than about 30 minutes.

CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 In another embodiment of the invention an eyegtass lens may be made by (a) placing a liquid, pol~ .i,atle lens-forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming cunl~oailion co-.-~,- iah~g a photoinitiator, (b) applying first ultraviolet light to at least one of the mold members for a selected first period of time such that a temperature of the lens forming S c~ -o~;~ion begins to increase~ (c) removing the first ultraviolet light from at least one of the mold members, thereby inhibiting the ~lllp~lalu~b of the Culll~Oailiûll from illcl~âaillg to a selected first le.llp~.alu.G, (d) repeatedly and alternate}y performing the following steps to complete the formation of a lens: (i) applying second ultraviolet light to at least one of the mold members for a selected second period of time and (ii) removing the second ultraviolet light from at least one of the mold members for a selected third period of time.
In an alternate embodi...~ of the invention an eyeglass lens may be made by (a) placing a liquid, pol~lllc.i~aiJlE lens forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming co...l,oailion cO~Ilpl iahlg a photoinitiator, (b) directing ultraviolet light at a first intensity toward at least one of the mold members for a selected first period of time such that a tc.ll~J.,.alul ~ of the 15 composition begins to increase, (c) decreasing the first intensity of ultraviolet light from at least one of the mold members, (d) repeatedly directing a plurality of pulses of ultraviolet to the lens forming composition through at least one of the mold members to complete r,....alion of a s~ cl~ U;AIIY clear eyeglass lens, at least one of the pulses lasting for a second period of time, and wherein a third period of time exists between application of at least two of the pulses.
An a~J~Jalalus of the invention may include: (a) a first mold member having a casting face and a non-casting face, (b) a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity, (c) a first pulse light generator adapted to 25 geneMte and direct a pulse of ultraviolet light toward at least one of the first and second mold members during use, and (d) a controller adapted to control the first pulse light generator such that ultraviolet light is directed in a plurality of pulses toward at least one of the first and second mold members, at least one of the pulses having a duration of less than one second.

A system of the invention may include (a) a lens forming co.. ,~osilioll comprising a photoinitiator, (b) a first mold member having a casting face and a non-casting face, (c) a second mold member having 8 casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity for the lens forming col.lposilioll, (d) a first pulse light generator adapted to generate and direct a pulse of 35 ultravioiet light toward at least one of the first and second mold members during use, (e) a controller adapted to control the first pulse light g~U~alul such that ultraviolet light is directed in a plurality of pulses toward at least one of the first and second mold members, at least one of the pulses having a duration of less than one second, and (f) wherein the system is adapted to cure the lens forming composition to form a ~..I.cl,., .1 ;~lly clear eyeglass lens in less than 30 minutes.

CA 022~1649 1998-10-13 W097/39880 PCTrUS97/06641 The lens forming c~ ..pss:~ion preferably co.--~,-ises at least one polyethylenic-functional monomer cont~ining at least two ethylenically u.,adlu.aled groups selected from acrylyl and methacrylyl, at least one polyethylenic-functional monomer cont~ininE at least three ethylenically unsalu.alcd groups selected from acrylyl 5 and methacrylyl, and/or an aromatic conf~ining bis(allyl ca.l,onalc~)-functional monomer.

- A system of the invention may include: (a) a lens forming composition cu.--~ hlg a photoinitiator, (b) a mold cavity chamber COIII~JI i lhlg a first mold member having a casting face and a non-casting face, a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the 10 first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity for the lens forming composition, (c) a first light generator adapted to generate and direct a ultraviolet light in a first intensity toward at least one of the first and second mold members during use, (d) a tc.llp.,.a~ulc sensor adapted to sense a tc.ll~-~,.d~ulc in the chamber or a t.,~ alUIc of air exiting the chamber, (e) a controller coupled to the temperature sensor and adapted to control the first light generator 15 such that the first intensity of ultraviolet light directed toward at least one of the first and second mold members is decreased when a t.,.llp~,.alulc; ."easu-,,d by the tc."p.,.alu.e sensor s~bst~nfiSIlly increases, and (f) wherein the system is adapted to cure the lens forming composition to form a su~ lly clear eyeglass lens in less than 30 minutes An apparatus of the invention may include (a) a first mold member having a casting face and a non-casting face, (b) a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity for a lens forming c~ po~;l ion (c) an ultraviolet light g.,..~,.al~/l adapted to generate and direct ultraviolet light toward at least one of the first and 25 second mold members during use, (e) a controller for controlling the intensity of light directed by the light g.,.lc,alol, (f) a light sensor adapted to measure the intensity of light directed by the ultraviolet light g.,u~.alol, the light sensor being adapted to signal the light generator to vary the intensity of the ultraviolet light being produced, and (g) a filter adapted to inhibit light other than ultraviolet light from impinging upon the light sensor In an alternate emboL",.,.,I, a system for making an eyeglass lens may include (a) a first mold member having a casting face and a non-casting face, (b) a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity for a lens forming cu---l~o~:~ira, (c) an ultraviolet light gc.n,.alo~ adapted to generate and direct ultraviolet light toward at least one of the first and second mold members during use, (d) a distributor adapted to direct air toward the non-casting face of at least one of the mold members, (e) a thermoelectric cooling system adapted to cool the air, and (f) a first blower adapted to receive effluent air that has cont Irted the non-casting face of the mold member and to recycle the effluent air to the distributor CA 022~1649 1998-10-13 W 097/39880 PCT~US97106~41 ln an embo~li...c..l, an eyeglass lens may be made by (a) placing a liquid, polymerizable lens forming composition in a mold cavity defined at least partially by a first mold member and a second mold member, the lens forming c("l,l,osilion c u...~ hlg a photoinitiator; (b) directing a plurality of puises of ultraviolet light toward the lens forming c~ )o~ilion through at least one of the mold members to initiate reaction of the lens forming 5 composition, at least one of the pulses having an intensity of at least about 10 milli~ atts/cm~; (c) sl~h5equent to the step of directing the plurality of pulses toward the lens forming c~,."posilion. directing ultraviolet light of a second intensity toward the lens forming co,-",osilion through at least one of the mold members to form a sl~hst~ -lti~lly clear eyeglass lens, the second intensity being less than about 350 microwatts/cm-; and (d) suhst~nti~lly cimllln-l~e~u~ with the step of directing ultraviolet of a second intensitv toward the lens forming 10 composition, directing air onto a non-casting face of at least one of the mold members to remove heat from the lens forming cc".-posilion.

A lens having a scratch resistant coating may be formed by: placing a first coating composition within a mold member, the mold member C~1111~1 i~;--g a casting face and a non-casting face. the coating co---posilion 15 u".,p, i~i"g a photoinitiator and being curable upon exposure to ultraviolet light; (a) placing a first coating c~ ilion within a mold member, the mold member CO~P~ iahlg a casting face and a non-casting face, the coating cu...~o~ilion c~""~ ",g a photoinitiator and being curable upon exposure to ultraviolet light; (b) spinning the mold member to distribute the first coating composition over the casting face; (c) directing ultraviolet light at the mold member to cure at least a portion of the first coating co,..posilion; ~d) placing a second coating 20 cn~ .ocilion within the mold member, the second coating co,."~o~ilion co-,-p.-~i-,g a photoinitiator and being curable upon exposure to ultraviolet light; (e) spinning the mold member to distribute the second coating cc ~.-~,o~iliou over the portion of the first coating co . l .u~;~ ;on that has been cured; (f) directing ultraviolet light at the mold member, thereby curing at least a portion of the second coating cun~;-osi~ ;01~ and forming a substS~ lti~lly clear co.lll,i.lalion coat cu.lll)li ,illg at least a portion of each of the first and second coating cullll)osilions; (g) 25 assembling the mold member with a second mold member to form a mold havine a cavity between the mold members; (h) placing a lens-forming composition within the cavity, the lens-formino c~,---posilion co...~ i..g a photoinitiator and being curable upon exposure to ultraviolet light; and (i) directing ultraviolet light at the mold to cure at least a portion of the lens-forming material to form a lens, and wherein the combination coat adheres to the cured portion of the lens-forming material.

BRIEF DESCRIPTION OF THE DRAWINGS

The above brief description as well as further objects, features and advantages of the methods and 35 alJIJalalu~ of the present invention will be more fully &~ ,ialed by reference to the following detailed deseription of presently preferred but nnnethelecs illustrative embodiments in accolJa"ce with the present invention when taken in conju,.. ,lio n with the ~c.. l.. ~/ing drawings in which Fig. I is a p~ ,c. ~ive view of an apparatus for producing a plastic lens CA 022~1649 1998-10-13 Fig. 2 is a cross-sectional view of the apparatus taken along line 2-2 of Fig. 1.

Fig. 3 is a cross-sectional view of the a~J~alaLua taken along line 3-3 of Fig. 2.
~ 5 Fig. 4 is a detail view of a COIllpOllC~lt of the a~ al~tus.

Fig. 5 is a detail view of a CUIII~J(Jn~ of the appalalus.

Fig. 6 is a cross-sectional view of a lens cell for use in an à,u~uala~US of the invention.

Fig. 7 is a view of an embodiment of a shutter system.

Fig. 8 is a top and side view of an embodiment of a heat distributor to be placed between a heat source 15 and a mold surface.

Fig. 9 is a schem~tic block diagram of an altemate process and system for making and postcuring a plastic lens.

Fig. 10 is a sçh~pm~tic diagram of an apparatus to apply UV light to a lens or mold assembly.

Fig. I l is a view of an embodiment of a lens.

Fig. 12 is a view of an embodiment of an oxygen barrier with photoinitiator.
Fig. 13 is a sçhPm~tic diagram of a lens curing alJpala~US with a light sensor and controller.

Fig. 14 is a s~hPm~tic view of the front of a lens curing a~l~Jaldlus.

Fig. 15 is a schPm~ic view of the side of a lens curing apparatus.

Fig. 16 is a view of an e.--bo~l;---l,.,l of a heat source and a heat distributor.

Fig. 17 is a view of various e...bûJi...e..la of a heat source and heat dial~ ulo~a.
Fig. 18 is a view of an embodiment of a heat source and a heat diallilJ.Ilol.

Fig. 19 is a view of an embodiment of two mold members and a gasket.

CA 022~1649 1998-10-13 W 097/39880 PCT~US97/06641 Fig. 20 is a graph illustrating a lc~ alule profile of a continuous radiation cycle.

Fig. 21 is a graph illustrating t~ p~.alul~ profiles for a continuous irradiation cycle and a pulse irradiation cycle employed with a mold/gasket set having a 3.00D base curve, and while applying cooled air at 58 5 ~ F to the mold/gasket set.

Fig. 22 is a chart illustrating qualitative relationships among curing cycle variables.

Fig. 23 is a graph illustrating temperature profiles for one curing cycle for a mold/gasket set having a 10 6.00D base curve and used with three different light levels.

Fig. 24 is a graph illustrating continuous and pulsed temperature profiles for a curing cycle employing a mold/gasket set with a 6.00D base curve.

Fig. 25 is a graph illustrating continuous and pulsed ~ .,.alul~ profiles for a curing cycle employing a mold/gasket set with a 4.50D base curve.

Fig. 26 is a graph illustrating continuous and pulsed t,,~ ,lalule profiles for a curing cycle employing a mold/gasket set with a 3.00D base curve.
Fig. 27 is a view of an embodiment of a system sirmllt?~leo~cly employing both a flash light source and a . ~ -uc UV (e.g., fluorescent) source.

Fig. 28 is an embodiment of a system simult~npoucly employing two flash light sources.
Fig. 29 is an embodiment of a system employing an ultraviolet light controller.

Fig. 30 depicts a sçhen~ ic view of a lens curing a~aldtUS.

30 Fig. 31 depicts a detail view of a thermoelectric cooling system.

Fig. 32 depicts a cross sectional view of a thermoelectric cooling system.

Fig. 33 depicts a thermoelectric module.
Fig. 34 depicts a flash lamp curing cycle.

Fig. 35 depicts a cross sectional view of a flat-top bifocal mold.

CA 022~1649 1998-10-13 W 097139880 PCTrUS97/06641 DESCRIPTION OF THE PREFERRED EMBODIMENTS

Apparatus, operating p-ucedu-~;" e91lipm-~nt, systems, methods, and cu"-posilions for lens curing using ultraviolet light are available from Rapid Cast, Inc., Q2100, Inc., and Fast Cast, Inc. in East Rockaway, New York and Louisville, Kentucky. The Fast Cast, Inc. publication entitled "Operation Manual For The FastCast - LenSystem" is hereby hlcc,l~JulaLed by rerel~lce~

Referring now to Fig. 1, a plastic lens curing chamber of the present invention is generally indicated by reference numeral 10. The lens curing chamber 10 preferably communicates through a plurality of pipes 12 with an air source (not shown), the purpose of which will be riiccllcced below.

As shown in Fig. 2, the plastic lens curing chamber 10 may include an upper lamp chamber 14, an irradiation chamber 16, and a lower lamp chamber 18. The upper lamp chamber 14 may be separated from the irradiation chamber 16 by a plate 20. The lower lamp chamber may be separated from the irradiation chamber 16 by a plate 22. The upper lamp chamber 14, the irradiation chamber 16. and the lower lamp chamber 18 may be isolated from ambient air by upper lamp chamber doors 24, irradiation chamber doors 26, and lower lamp chamber doors 28, respectively. While the upper lamp chamber doors 24, the irradiation chamber doors 26 and the lower lamp chamber doors 28 are shown in Fig. I as including two cu,-.,~l-ooding door members, those of ordinary skill in the art will recognize that the doors 24, 26 and 28 may include single or multiple door members.
The upper lamp chamber doors 24, the irradiation chamber doors 26 and the lower lamp chamber doors 28 may be slidingly mounted in guides 30. As shown in Fig. 2, vents 32 may communicate with upper lamp chamber 14 and lower lamp chamber 18 by way of cU,,.,~o~ ing vent chambers 34 and openings 36 disposed in plate 20 and plate 22. Each vent 32 may be shielded by a vent cover 38.
As shown in Fig. 3, vents 33 may be disposed in the irradiation chamber doors 26 and communicate with irradiation chamber 16. Each vent 33 may be shielded by a vent cover 35.

As shown in Figs. 2 and 3, a plurality of light b~ aling devices or lamps 40 may be disposed within each of upper lamp chamber 14 and lower lamp chamber 18. Preferably, upper lamp chamber 14 and lower lamp chamber 18 each include three lamps 40 that are arranged in a triangular fashion in which the lamps 40 in the upper lamp chamber 14 are disposed with the point of the triangle pointing upwards whereas the lamps 40 in the lower lamp chamber 18 are disposed with the point of the triangle pointing downward. The lamps 40, preferably, generate ultraviolet light having a wavelength in the range of at least approximately 300 nm to 400 nm since the effective wavelength spectrum for curing the lens forming material lies in the 300 nm to 400 nm region. The lamps 40 may be s.~ Jol~,d by and electrically cuun~,~,t~,d to suitable fixtures 42.

An exhaust fan 44 may communicate with upper lamp chamber 14 while an exhaust fan 46 may communicate with lower lamp chamber 18.

CA 022~1649 1998-10-13 W O 97139880 PCT~US97/06641 As noted above, the upper lamp chamber 14 may be separated from the illadidLion chamber 16 by plate 20. Similarly, lower lamp chamber 18 may be separated from the irradiation chamber 16 by plate 22. The plates 20 and 22 may include apertures 48 and 50, respectively, through which the light generated by lamps 40 may be directed so as to impinge upon a lens cell 52 (shown in phantom in Fig. 2). The diameter of the lens cell 52 is preferably ap~oxil,ld~ly 74 mm. The apertures 48 and 50 preferably range from about 70 mm to about 140 mm.

In one embodiment an upper light filter 54 rests upon plate 20 while a iower light filter 56 rests upon 10 plate 22 or is sl~ ,ull~,d by brackets 57. The upper light filter 54 and lower light filter 56 are shown in Fig. 2 as being made of a single filter member~ however, those of ordinary skill in the art will recognize that each of the upper light filter 54 and lower light filter 56 may include two or more filter members. The colllpol,cllL~ of upper light filter 54 and lower light filter 56 preferably are modified r~p~nrling upon the ~halackilistics ofthe lens to be molded. For instance~ in a preferred embodimem for making negative lenses~ the upper light filter 54 includes a 15 plate of Pyrex glass that is frosted on both sides resting upon a plate of clear Pyrex glass. The lower light filter 56 includes a plate of Pyrex glass frosted on one side resting upon a plate of clear Pvrex glass with a device for reducing the intensity of ultraviolet light incident upon the center portion in relation to the edge portion of the lens being disposed between the plate of frosted Pyrex and the plate of clear Pyrex glass.

Conversely, in a preferred allang~lllcllt for producing positive lenses, the upper light filter 54 includes a plate of Pyrex glass frosted on one or both sides and a plate of clear Pyrex glass resting upon the plate of frosted Pyrex glass with a device for reducing the intensity of ultraviolet light incident upon the edge portion in relation to the cemer portion of the lens being disposed between the plate of clear Pyrex glass and the plate of frosted Pyrex glass. The lower light filter 56 includes a plate of clear Pyrex glass frosted on one side resting upon a plate 25 of clear Pyrex glass with a device for reducing the intensity of ultraviolet light incident upon the edge portion in relation to the center portion of the lens being disposed between the plates of clear Pvrex glass. In this arrangement, in place of a device for reducing the relative intensity of ultraviolet light incident upon the edge portion of the lens, the diameter of the aperture 50 can be reduced to achieve the same result, i.e. to reduce the relative intensity of ultraviolet light incident upon the edge portion of the lens.
It will be apparent to those skilled in the art that each filter 54 or 56 could be composed of a plurality of filter members or include any other means or device effective to reduce the light to its desired intensity, to diffuse the light and/or to create a light intensity gradient across the lens cell 52. Alternately, in certain embodiments no filter elements may be used.
Preferably, the upper light filter 54 or the lower light filter 56 each include at least one plate of Pyrex glass having at least one frosted surface. Also, either or both of the upper light filter 54 and the lower light filter 56 may include more than one plate of Pyrex glass each frosted on one or both surfaces, and/or one or more sheets of tracing paper. After passing through frosted Pyrex glass, the ultraviolet light is believed to have no CA 022~1649 1998-10-13 WO 97/39880 PCTrUS97/06641 sharp intensity ~ c~...l;...liti~s which is believed to lead to a reduction in optical distortions in the finished lens in some inct~nces Those of ordinary skill in the art will recognize that other means may be used to diffuse the ultraviolet light so that it has no sharp intensity discù..~ c Preferably disposed within the irradiation chamber 16 are a left stage 58~ a center stage 60. and a right stage 62, each of which preferably includes a plurality of steps 64. The left stage 58 and center stage 60 define a - leR irradiation chamber 66 while the right stage 62 and center stage 60 define a right irradiation chamber 68. A
cell holder 70, shown in phantom in Fig. 2 and in detail in Fig. 4, may be disposed within each of left irradiation chamber 66 and right irradiation chamber 68. The cell holder 70 may include a peripheral step 72 that is designed to allow a cell holder 70 to be supported upon cu.. ~,' y steps 64 of left stage 58 and center stage 60, and center stage 60 and right stage 62, respectively. As shown in Fig. 4, each cell holder 70 also may include a central bore 74 to allow the passage Ih~ uilgh of ultraviolet light frûm the lamps 40 and an annular step 76 which is designed to support a lens cell 52 in a manner described below.

As shown in Fig. 6, each lens cell 52 may include opposed mold members 78, separated by an annular gasket 80 to define a lens molding cavity 82. The opposed mold members 78 and the annular gasket 80 may be shaped and selected in a manner to produce a lens having a desired diopter.

r~he mold members 78 are preferably formed of any suitable material that will permit rays of ultraviolet light to pass therethrough. The mold members 78 are preferably formed of glass. Each mold member 78 has an outer p. .ilJLl,.al surface 84 and a pair of opposed surfaces 86 and 88 with the surfaces 86 and 88 being precision ground. Preferably the mold members 78 have desirable ultraviolet light tr~ncmiccion characteristics and both the casting surface 86 and non-casting surface 88 preferably have no surface aberrations, waves, scratches or other defects as these may be reproduced in the finished lens.
As noted above, the mold members 78 are adapted to be held in spaced apart relation to define a lens molding cavity 82 between the facing surfaces 86 thereof. The mold members 78 are preferably held in a spaced apart relation by a T-shaped flexible annular gasket 80 that seals the lens molding cavity 82 from the exterior of the mold members 78. In use, the gasket 80 may be su~-~,u- l~,d on the annular step 76 of the cell holder 70.
In this manner~ the upper or back mold member 90 has a convex inner surface 86 while the lower or front mold member 92 has a concave inner surface 86 so that the resulting lens molding cavity 82 is shaped to form a lens with a desired configuration. Thus, by selecting the mold members 78 with a desired surface 86, lenses with different CllalaC~ ialil,a, such as focal lengths, may be made by the dlJ~Jalalua 1O.
Rays of ultraviolet light em~n~ing from lamps 40 pass through the mold members 78 and act on a lens forming material disposed in the mold cavity 82 in a manner ~iiccllcsed below so as to form a lens. As noted above, the rays of ultraviolet light may pass through a suitable filter 54 or 56 to impinge upon the lens cell 52.

CA 022~1649 1998-10-13 I'he mold members 78, pre~'erably, are lormed trom a material that will not allow ultraviolet radiation having a ~ai~ below at~lu~dlll ~Iy 300 nm to pass therethrough. Suitable materials are Schott Crown, S-l or S-3 glass .,.~.."r- ,~".~d and sold by Schott Optical Glass Inc., of Duryea, Pennsylvania or Corning 8092 glass sold by Corning Glass of Coming, New York. A source of molds may be Opticas Devlyn S.A. (Mexico City, S Mexico) and/or Titmus Inc. (F-~d-i-,k~b~ , Virginia).

The annular gasket 80 may be formed of vinyl material that exhibits good lip finish and ~.,~
5urr.~ flexi~ilit,v at conditions throughout the lens curing process. In a preferred embodiment, the annular gasket 80 is formed of silicone rubber material such as GE SE6035 which is commercially available from General 10 Electric. In another preferred c.--bo.l;..u".L~ the annular gasket 80 is formed of copolymers of ethylene and vinyl acetate which are co...r..c.~;ally available from E. I. DuPont de Nemours & Co. under the trade name ELVAX7.
Preferred ELVAX7 resins are ELVAX7 350 having a melt index of 17.3-20.9 dg/min and a vinyl acetate content of 24.3-25.7 wt. %, ELVAX7 250 having a melt index of 22.0-28.0 dg/min and a vinyl acetate content of 27.2-28.8 wt. %, ELVAX7 240 having a melt index of 38.0-48.0 dg/min and a vinyl acetate content of 27.2-28.8 15 wt. %, and ELVAX7 150 having a melt index of 38.0-48.0 dg/min and a vinyl acetate content of 32.0-34.0 wt. %.
Regardless of the particular material, the gaskets 80 may be prepared by conventional injection molding or Cc ~ a;On molding terhnitlu,oc which are well-known by those of ordinary skill in the art.

As shown in phantom in Fig. 2, in section in Fig. 3, and in detail in Fig. 5, an upper and lower air 20 distribution device 94 is disposed in each of left hlad;dlion chamber 66 and right irradiation chamber 68. Each air distribution device 94 is c(~ule~u d to a pipe 12. As shown in Fig. 5, each air distribution device 94 includes a plenum portion 95 and a s~ i-lly cylindrical opening 96 having orifices 98 disposed therein to allow for the p--lC;on of air from the air distribution device 94. The diameter of the orifices 98 may be constant, or may vary around the circumference of cylindrical opening 96 preferably reaching a m~imum when directly opposite the 25 plenum portion 95 of air distribution device 94 and preferably reaching a minimum immediately adjacent the plenum portion 95. In addition, the orifices 98 are designed to blow air toward a lens cell 52 that may be disposed in a lens cell holder 70 and installed in left irradiation chamber 66 or right irradiation chamber 68.

In operation, the dp~Jala~ of the present invention may be all,ulu~l;alely configured for the production 30 of positive lenses which are relatively thick at the center or negative lenses which are relatively thick at the edge.
To reduce the lil~lihood of premature release, the relatively thick portions of a lens preferably are polymerized at a facter rate than the relatively thin portions of a lens.

The rate of polymerization taking place at various portions of a lens may be controlled by varying the 35 relative intensity of ultraviolet light incident upon particular portions of a lens. The rate of polymerization taking place at various portions of a lens may also be controlled by directing air across the mold members 78 to cool the lens cell 52.

CA 022C,1649 1998-10-13 For positive lenses the intensity of incident ultraviolet light is preferably reduced at the edge portion of the lens so that the thicker center portion of the lens polymerizes faster than the thinner edge portion of the lens.
Conversely, for a negative lens, the intensity of incident ultraviolet light is preferably reduced at the center portion of the lens so that the thicker edge portion of the lens polymerizes faster than the thinner center portion of 5 the lens. For either a positive lens or a negative lens, air may be directed across the faces of the mold members 78 to cool the lens cell 52. As the overall intensity of incident ultraviolet light is increased, more cooling is needed which can be accom,plished by either or both of increasing the velocity of the air and reducing the lelllp."dLI~lt of the air.

It is well known by those of ordinary skill in the art that lens forming materials having utility in the present invention tend to shrink as they cure. If the relatively thin portion of a lens is allowed to polymerize before the relatively thick portion, the relatively thin portion will tend to be rigid at the time the relatively thick portion cures and shrinks and the lens will either release prematurely from or crack the mold members 78.
Accordingly, when the relative intensity of ultraviolet light incident upon the edge portion of a positive lens is 15 reduced relative to the center portion~ the center portion polymerizes faster and shrinks before the edge portion is rigid so that the shrinkage is more uniform. Conversely, when the relative intensity of ultraviolet light incident upon the center portion of a negative lens is reduced relative to the edge portion, the edge portion polymerizes faster and shrinks before the center becomes rigid so that the shrinkage is more uniform.

The variation of the relative intensity of ultraviolet light incident upon a lens may be accomplished in a variety of ways. According to one method, in the case of a positive lens, a ring of opaque material may be placed between the lamps 40 and the lens cell 52 so that the incident ultraviolet light falls mainly on the thicker center portion of the lens. Conversely, for a negative lens, a disk of opaque material may be placed between the lamps 40 and the lens cell 52 so that the incident ultraviolet light falls mainly on the edge portion of the lens.
According to another method, in the case of a negative lens, a sheet material having a variable degree of opacity ranging from opaque at a central portion to tlalla~al~ ul at a radial outer portion is disposed between the lamps 40 and the lens cell 52. Conversely, for a positive lens, a sheet material having a variable degree of opacity ranging from lla~l;7~Ja~,nt at a central portion to opaque at a radial outer portion is disposed between the lamps 40 30 and the lens cell 52.

Those of ordinary skill in the art will recognize that there are a wide variety of techniques other than those cn.~ above for varying the intensity of the ultraviolet light incident upon the opposed mold members 78.
In some embod....~ s" the intensity of the incident light has been measured and determined to be a~ lur.hllately 3.0 to 5.0 milliwatts per square c~.n;~ (mWlcm2) prior to passing through either the upper light filter 54 or the lower light filter 56 and the total intensity at the thickest part of the lens ranges from 0.6 to 2.0 mW/cm' while the intensity at the thinnest portion of the lens ranges from 0.1 to 1.5 mWlcm2. In some CA 022~1649 1998-10-13 emborlim--ntc the overall light intensity incident on the lens cell 52 has less of an impact on the final product than the relative light intensity incident upon the thick or thin portions of the lens so long as the lens cell 52 is aurGl i~ ly cooled to reduce the polymerization rate to an acceptable level.

It has been determined that in some embodiments the finished power of an ultraviolet light polymerized lens may be controlled by m~nipulating the distribution of the incident ultraviolet light striking the opposed mold members 78. For instance, for an identical combination of mold members 78 and gasket 80, the focusing power of the produced lens may be increased or decreased by changing the pattern of intensity of ultraviolet light across the lens mold cavity 82 or the faces of the opposed mold members 78.
As the lens forming material begins to cure, it passes through a gel state, the pattern of which within the lens cell 52 leads to the proper distribution of internal stresses generated later in the cure when the lens forming material begins to shrink.

As the lens forming material shrinks during the cure, the opposed mold members 78 will preferably flex as a result of the different amounts of shrinkage between the relatively thick and the relatively thin portions of the lens. When a negative lens, for example, is cured, the upper or back mold member 90 will preferably flatten and the lower or front mold member 92 will preferably steepen with most of the flexing OC~ullillg in the lower or front mold member 92. Conversely, with a positive lens, the upper or back mold member 90 will preferably 20 steepen and the lower or front mold member 92 will preferably flatten with most of the flexing occurring in the upper or back mold member 90.

By varying the intensity of the ultraviolet light between the relatively thin and the relatively thick portions of the lens in the lens forming cavity 82, it is possible to create more or less total flexing. Those light 25 conditions which result in less flexing will tend to minimize the possibility of ~ ;llla~u~e release.

The initial curvature of the opposed mold members 78 and the center thickness of the lens produced can be used to compute the theoretical or predicted power of the lens. The ultravioiet light con-lition~ can be m~nirul -~Pd to alter the power of the lens to be more or less than predicted. The greater the diameter of the disk 30 of opaque material, the more negative (-) power the resultant lens will tend to exhibit.

When the lenses cured by the ultraviolet light are removed from the opposed mold members 78, they are typically under a stressed con(~ition It has been ~PterrninPd that the power of the lens can be brought to a final resting power, by subjecting the lenses to a post-curing heat ~l~d~ C.Il to relieve the internal stresses developed 35 during the cure and cause the curvature of the front and the back of the lens to shift. Typically, the lenses are cured by the ultraviolet light in about 10-30 minutes (preferably about 15 minutes). The post-curing heat l~dn~e~l~ is con~ rtPd at approximately 85-120 ~C for d~J~Jlv~illldlely 5-15 minutes. Preferably, the post-curing heat treatment is con~ rted at 100-110 ~C for a~-~ lu~ ately 10 minutes. Prior to the post-cure, the lenses generally have a lower power than the final resting power. The post-curing heat treatment reduces yellowing of CA 022~1649 1998-10-13 WO 97/39880 PCTrUS97/06641 the lens and reauces stress m the lens to alter the power thereot to a ~mal power. I he post-cunng heat Ilt, can be col!durted in a conventional convection oven or any other suitable device.

In addition, as described below, in certain embodiments heat may be conductively applied to the molds 5 and/or lens, thereby enhancing the quality of the cured lenses.

The ultraviolet lamps 40 preferably are m~int~in.~d at a ~ .aIul~ at which the lamps 40 deliver ,,,~x i.. output. The lamps 40, preferably, are cooled because the intensity of the light produced by the lamps 40 11...,1..~5 when the lamps 40 are allowed to overheat. In the apparatus depicted in Fig. 2. the cooling of the 10 lamps 40 is accomplished by sucking ambient air into the upper lamp chamber 14 and lower lamp chamber 18 through vent 32, vent chambers 34 and openings 36 by means of exhaust fans 44 and 46, respectively. Excessive cooling of the lamps 40 should be avoided, however, as the intensity of the light produced by the lamps 40 is reduced when the lamps 40 are cooled to an excessive degree.

As noted above. the lens cell 52 is preferably cooled during curing of the lens forming material as the overall intensity of the incident ultraviolet light is increased. Cooling of the lens cell 52 generally reduces the ' ' Plih~od of premature release by slowing the reaction and improving adhesion. There are also improvements in the optical quality, stress cl-~lacL~ ,s and impact n~sisla--ce of the lens. Cooling of the lens cell 52 is plcr~,,ably accomplished by blowing air across the lens cell 52. The air preferably has a temperature ranging 20 between 15 and 85~F (about -9.4~C to 29.4~C) to allow for a curing time of between 30 and 10 minutes. The air distribution devices 94 depicted in Fig. 5 have been found to be particularly advantageous as they are specifically designed to direct air directly across the surface of the opposed mold members 78. After passing across the surface of the opposed mold members 78, the air < ~ ;..g from the air distribution devices 94 is vented through vents 33. Alternately the air ~m~n~inp~ from the air distribution devices 94 may be recycled back to an air cooler.
The lens cell 52 may also be cooled by disposing the lens cell in a liquid cooling bath.

The opposed mold members 78 are preferably thoroughly cleaned between each curing run as any dirt or other impurity on the mold members 78 may cause pl~lldtUI~; release. The mold members 78 are cleaned by any 30 conventional means well known to those of ordinary skill in the art such as with a domestic cleaning product, i.e., Mr. CleanTM available from Proctor and Gamble. Those of ordinary skill in the art will recognize, however, that many other tenhniques may also be used for cleaning the mold members 78.

Yellowing of the finished lens may be related to the monomer cu---~ ilion, the identity of the 35 photoinitiator, and the concentration of the photoinitiator.

When casting a lens, particularly a positive lens that is thick in the center, cracking may be a problem.
Addition polymerization reactions, including photoch~mical addition polymerization reactions, are exothermic.
During the process, a large te.ll~,.dIul~ gradient may build up and the resulting stress may cause the lens to crack.

CA 022~1649 1998-10-13 The forrnation of optical distortions usually occurs during the early stages of the polymerization reaction during the l~al,aru.",ation of the lens forming co"",oailion from the liquid to the gel state. Once patterns leading to optical distortions form they are difficult to eliminate. When gelation occurs there typically is a rapid 5 l~ d~Ul~ rise. The exothermic polymc,i~liu" step causes a t~lllp~,lalule increase, which in turn causes an increase in the rate of polymeri_ation, which causes a further increase in t~ Jclalult;. If the heat exchange with the surroundings is not sufficient enough there will be a runaway situation that leads to p,~ l,lalule release, the a~ a~allce of thermally caused striations and even 1,.~ ' 37f .

Accordingly, when contimlonc UV light is applied, it is preferred that the reaction process be smooth and not too fast but not too slow. Heat is preferably not generated by the process so fast that it cannot be çx~ ' g_d with the surroun~iingC The incident ultraviolet light intensity preferably is adjusted to allow the reaction to proceed at a desired rate. It is also preferred that the seal between the annular gasket 80 and the opposed mold members 78 be as complete as possible.
Factors that have been found to lead to the production of lenses that are free from optical dislu,~ions are (I) achieving a good seal between the annular gasket 80 and the opposed mold members 78; (2) using mold members 78 having surfaces that are free from defects; (3) using a formulation having an alJIJlulJliale type and con~ aliull of photoinitiator that will produce a ,eâsonablc rate of t. llll~ lalulc rise; and (4) using a 20 ho".o~5eneous formulation. Preferably, these cnn~1itionc are optimized.

~ ,lllalul~; release of the lens from the mold will result in an incompletely cured lens and the production of lens defects. Factors that cullllibule to ~ lld~ult release are (I) a poorly assel"bled lens cell 52; (2) the presence of air bubbles around the sample edges; (3) i",~ ,Lion in gasket lip or mold edge; (4) ulalJ~Jlu~lid~e 25 formulation: (5) uncontrolled temperature rise: and (6) high or nonuniforrn shrinkage. Preferably, these cnr-iitionc are minimi7P~i P~ alul~ release may also occur when the opposed mold members 78 are held too rigidly by the annular gasket 80. Preferably, there is aurr~ flexibility in the annular gasket 80 to permit the opposed mold 30 members 78 to follow the lens as it shrinks. Indeed, the lens must be allowed to shrink in diameter slightly as well as in thirknPcc The use of an annular gasket 80 that has a reduced degree of stirkinesc with the lens during and after curing is therefore desirable.

In a preferred terhni~lue for filling the lens molding cavity 82, the annular gasket 80 is placed on a 35 concave or front mold member 92 and a convex or back mold member 90 is moved into place. The annular gasket 80 is then pulled away from the edge of the back mold member 90 at the uppermost point and a lens forming culll~Joailion is injected into the lens molding cavity 82 until a small amount of the lens forming c..~ .os;~inn is forced out around the edge. The excess is then removed, preferably, by vacuum. Excess liquid CA 022~1649 1998-10-13 that is not removed could spill over the face of the back mold member 90 and cause optical distortion in the finished lens.

Despite the above problems. the advantages offered by the radiation cured lens molding system clearly 5 outweigh the disadvantages. The advantages of a radiation cured system include a significant reduction in energy requirements curing time and other problems normally ~ccori~tPd with conventional thermal systems.

The lens forming material may include any suitable liquid monomer or monomer mixture and any suitable photos~n~ e initiator. The lens forming material, preferablv, does not include any co...l)on~,t~ other 10 than a photoinitiator, that absorbs ultraviolet light having a wavelength in the range of 300 to 400 nm. The liquid lens forming material is preferably filtered for quality control and placed in the lens molding cavity 82 by pulling the annular gasket 80 away from one of the opposed mold members 78 and injecting the liquid lens forming material into the lens molding cavity 82. Once the lens molding cavity 82 is filled with such material, the annular gasket 80 is replaced into its sealing relation with the opposed mold members 78.
Those skilled in the art will recognize that once the cured lens is removed from the lens molding cavity 82 by riic~ccPmbling the opposed mold members 78, the lens can be further processed in a conventional manner, such as by grinding its p~ Jh(,.al edge.

According to the present invention a polymerizable lens forming cGI~lpocilinn includes an aromatic-cnnt~ining bis(allyl ca-l,ur.dle)-functional monomer and at least one polyethylenic-functional monomer conr~ining two ethylenically ullsdluld~d groups selected from acrylyl and methacrylyl. In a preferred embodiment, the cu...po~iIion further includes a suitable photoinitiator. In other preferred embo~lim~-ntc the c~ ,o~;lion may include one or more polyethylenic-functional monomers containing three ethylenically 25 ullsd~uld~ed groups selected from acrylyl and methacrylyl, and a dye.

Aromatic-containing bis(allyl ca.l,onà~t)-functional monomers which can be utilized in the practice of the present invention are bis(allyl calb, ~) of dihydroxy aromatic-cont~ininp material. The dihydroxy aromatic-containing material from which the monomer is derived may be one or more dihydroxy 30 aromatic-cont~ining compounds. Preferably the hydroxyl groups are attached directly to nuclear aromatic carbon atoms of the dihydroxy aromatic-cont~ining compounds. The monomers are themselves known and can be prepared by ,u~ucelu~c~ well known in the art.

CA 022C.1649 1998-10-13 Ihe aromatic-containing bis(allyl ca.L.ol-dl~)-functional monomers can be r~ s~ ed by the formula:

~7 Ro S CH2=CCH20CO-A,-OCOcH~c=cH2 (1) O O

10 in which A, is the divalent radical derived from the dihydroxy aromatic-cont~inine material and each Ro is inAPpPn~A~pntly hydrogen, halo, or a C~-C4 alkyl group. The alkyl group is usually methyl or ethyl. Examples of Ro include hydrogen, chloro, bromo, fluoro, methyl, ethyl, n-propyl, isopropyl and n-butyl. Most commonly Ro is hydrogen or methyl; hydrogen is preferred. A subclass of the divalent radical A, which is of particular usefulness is represented by the forrnula:
~R,)a (R,)a (R,)a ~Q~ (Il) n in which each R, is in~ f-,A~ iy alkyl cu-,~ e from I to about 4 carbon atoms, phenyl, or halo; the average value of each a is independently in the range of from 0 to 4; each Q is in~PppnAently oxy, sulfonyl, alkanediyl 25 having from 2 to about 4 carbon atoms, or alkylidene having from I to about 4 carbon atoms; and the average value of n is in the range of from 0 to about 3. Preferably Q is methylethylidene, viz., isopropylidene.

Preferab y the value of n is zero, in which case A, is t, ",L;.~ d by the formula:

(R,)a (R,)a ~_Q~ (111) 35 in which each R" each a, and Q are as Aiccllcc~pd in respect of Formula 11. Preferably the two free bonds are both in the ortho or para positions. The para positions are especially preferred.

The dihydroxy aromatic-cnn~ining compounds from which A, is derived may also be polyol-functional chain extended cornpoun~lc Examples of such compounds include alkaline oxide extended bisphenols. Typically W O 97/39880 PCTrUS97/06641 the alkaline oxide employed is ethylene oxide~ propylene oxide. or mixtures thereof. By wav of exemplifi~tion when para, para-bi~l,h~"-ols are chain extended with ethylene oxide, the bivalent radical Al may oRen be s~n~ed by the formula:

(Rl)a (R,)a ~CH2CH20),~ ~(OCH2CH2)j~ (IV) where each R" each a, and Q are as Aiccl-cced in respect of Formula 11, and the average values of j and k are each p~n~Pntly in the range of from about I to about 4.

The preferred aromatic-con~ining bis(allyl carbonate)-functional monomer is represented by the I S formula:

CH2=CHCH,OC i) - O - C - O - OCOCH2CH=CH2 (V) ~) CH3 ~J

and is commonly known as bisphenol A bis(allyl carbonate).

A wide variety of cnmpo~nAc may be used as the polyethylenic functional monomer con-~ining two or three ethylenically unsaturated groups. The preferred polyethylenic functional compounds containing two or three ethylenically l..lsalu.al~d groups may be generally described as the acrylic acid esters and the methacrylic acid esters of aliphatic polyhydric alcohols, such as, for example, the di- and triacrylates and the di- and cll~ac~ylates of ethylene glycol, triethylene glycol, tetraethylene glycol, tetramethylene glycol, glycidyl, 30 diethyleneglycol, butyleneglycol, propyleneglycol, pentanediol, hex~nPAic l, trimethylolpropane, and tripropyleneglycol. Examples of specific suitable polyethylenic - functional monomers cont~inin,o two or three ethylenically unsaturated groups include trimethyloipropanetriacrylate (TMPTA), tetraethylene glycol diacrylate (TTEGDA), tripropylene glycol diacrylate (TRPGDA), 1,6 hp~np~liolAimeth~rrylate (HDDMA), and ht~x:~n~AiolA~ rylate (HDDA).
In general, a photoinitiator for initiating the polymerization of the lens forming composition of the present invention, preferably, exhibits an ultraviolet absorption spectrum over the 300-400 nm range. High absorptivity of a photoinitiator in this range, however, is not desirable, especially when casting a thick lens. The following are examples of illustrative photoinitiator compounds within the scope of the invention: methyl CA 022~1649 1998-10-13 W O 97139880 PCTrUS97106641 benzoylformate, 2-hydroxy-2-methyl- 1 -phenylpropan- I -one, I -hydroxycyclohexyl phenyl ketone, 2,2-di-sec-butoxyac~(Jul,c~lolle~ 2,2-diethoxyacetophenone~ 2.2-diethoxy-2-phenyl-accIo~ henonc, 2,2-dimethoxy-2-phenyl-acetu~,l,cnone, benzoin methyl ether, benzoin isobutyl ether. benzoin. benzil, benzyl disulfide, 2,4-dihydroxyl,~,.,zolullc.,one, benzylidene~ one bc.,~o~ ...one and acetophenone. Preferred 5 photoinitiator componnAc are l-hydroxycyclohexyl phenyl ketone (which is commercially available from Ciba-Geigy as Irgacure 184), methyl benzoylformate (which is commercially available from Polysciences~ Inc.), or mixtures thereof.

Methyl benzoylformate is a generally preferred photoinitiator because it tends to provide a slower rate of 10 polymerization. The slower rate of polymerization tends to prevent excessive heat buildup (and resultant cracking of the lens) during pol~...~,. ;~alion~ In addition, it is relatively easy to mix liquid methyl benzoylformate (which is liquid at ambient ~ l,u.,~a~ ,;,) with many acrylates, diacrylates, and allyl ~,all~OIIal~ coll.lJuul,d~ to form a lens forming co",po~;Iion. The lenses produced with the methyl benzoylformate photoinitiator tend to exhibit more favorable stress patterns and uniformity.
A strongly absorbing photoinitiator will absorb most of the incident light in the first millimeter of lens thir~nPc~ causing rapid polymerization in that region. The remaining light will produce a much lower rate of polymerization below this depth and will result in a lens that has visible distortions. An ideal photoinitiator will exhibit high activity, but will have a lower extinction coefficient in the useful range. A lower ~Ytinrtion 20 cG~rri~ of photoinitiators at longer wav~ Il,s tends to allow the ultraviolet radiation to penetrate deeper into the reaction system. This deeper p.,ll~IIalion of the ultraviolet radiation allows photoinitiator radicals to form uniformly throughout the sample and provide excellent overall cure. Since the sample can be irradiated from both top and bottom, a system in which appreciable light reaches the center of the thickest portion of the lens is preferred. The photoinitiator solubility and cu~ Jalil,ility with the monomer system is also an i 25 requirement.

An ,otl~litionol consideration is the effect of the photoinitiator fragments in the finished polymer. Some photoinitiators generate rla~",-c.-L~ that impart a yellow color to the finished lens. Although such lenses actually absorb very little visible light, they are cosmetically undesirable.
Photoinitiators are often very system specific so that photoinitiators that are efficient in one system may function poorly in another. In addition, the initiator conc.,.-IIdlion to a large extent is dependl~nt on the incident light intensity and the monomer co""~o,;~ion. The identity of the initiator and its conc~ alion are illlpOIIdl~l for any particular formulation. A conc~ alion of initiator that is too high tends to lead to cracking and yellowing of 35 the lens. Conce.-I-alions of initiator that are too low tend to lead to incc...~lctc polymerization and a soft material.

Dyes and/or pigments are optional materials that may be present when high tr~ncmiccion of light is not necessary.

CA 022~1649 1998-10-13 The listing of optional ingredients ~licc--cced above is by no means exhaustive. These and other ingredients may be employed in their ~,ualu.,.a.y amounts for their customary purposes so long as they do not seriously interfere with good polymer formulating practice.

According to a preferred embodiment of the present invention, the preferred aromatic-containing bis(allyl ~alb~ ) functional monomer, bisphenol A bis(allyl calb~ t~) is admixed with one or more faster - reacting polyethylenic functional monomers C~,--Ldil-i.lg two acrylate or methacrylate groups such as 1,6 h~Y~n~-liol d;-. P~ ylate (HDDMA), 1,6 hf-- ed ol diacrylate (HDDA), tetraethylene glycol diacrylate (TTEGDA), and tripropylene glycol diacrylate (TRPGDA) and optionally a polyethylenic functional monomer cont~ining three acrylate groups such as trimethylolpropane triacrylate (TMPTA). Generally, cornpo--n~c c- ~ ing acrylate groups polymerize much faster than those cont~ininP allyl groups.

In one embodiment, the lamps 40 generate an intensity at the lamp surface of approximately 4.0 to 7.0 mW/cm2 of ultraviolet light having wavelengths between 300 and 400 nm, which light is very uniformly 15 di~tt;l,~ d without any sharp .I.'Cu.~ c throughout the reaction process. Such bulbs are collllllcidlly available from Sylvania under the trade designation Sylvania Fluorescent (FlST8/2052) or Sylvania Fluorescent (F15T8/350BL/18") GTE.

As noted above, ultraviolet light having ~a~,le..gll.s between 300 and 400 nm is preferred because the 20 photoinitiators accol.li..g to the present invention, preferably, absorb most efficiently at this wavelength and the mold members 78, preferably, allow maximum tr~ncmiccion at this wa~ h ..gLh.

It is preferred that there be no sharp intensity gradients of ultraviolet radiation either hcuizûlllally or vertically through the lens composition during the curing process. Sharp intensity gradients through the lens may 25 lead to defects in the finished lens.

According to one embodiment of the present invention, the liquid lens forming u,...l~oai~ion includes bisphenol A bis(allyl Calùu.laL~) in place of DEG-BAC. The bisphenol A bis(allyl-carbonate) monomer has a higher refractive index than DEG-BAC which allows the ~udu~,~iùn of thinner lenses which is hllpolLall~ with 30 relatively thick positive or negative lenses. The bisphenol A bis(allyl-call,u--at~,) monomer is cu...-..c.- ;ally available from PPG Industries under the trade name HIRI I or CR-73. Lenses made from this product so..u.tu..c~
have a very slight, barely detectable, degree of yellowing. A small amount of a blue dye concicting of 9, 10-aulhlac~ onç I-hydroxy-4-[(4-methylphenyl)amino] available as Thermoplast Blue 6~4 from BASF
Wyandotte Corp. is plefc.dbly added to the CulllpGai~iull to cuulll~.~a~ the yellowing. In addition, the yellowing 35 tends to dia~y~ àl if the lens is al-bj~c. ~ to the above-described post-cure heat treatment. Moreover, if not post-cured the yellowing tends to d;aàppea~ at ambient t~.-.p~ u-~ after approximately 2 months.

TTEGDA, available from Sartomer and Radcure. is a diacrylate monomer that, preferably, is included in the c~ .u,;l ion because it is a fast polymerizing monomer that reduces yellowing and yields a very clear product.

CA 022~1649 1998-10-13 W O 97/39880 PCT~US97/06641 If too much TTEGDA is included in the most preferred cu~lpo~ ont i.e. greater than about 25% by weight, however, the finished lens may be prone to cracking and may be too flexible as this material softens at c.alul~,a above 40NC. If TTEGDA is excluded ~Itogeth~r, the finished lens may to be brittle.

HDDMA, available from Sartomer, is a dimethacrylate monomer that has a verv stiff ~ hone between the two methacrylate groups. HDDMA, preferably, is included in the comrositi~m because it yields a stiffer polymer and increases the hardness and strength of the finished lens. This material is quite compatible with the bisphenol A bis(allyl ~,albùlld~e) monomer. HDDMA Cu~ ;iJ~ ,s to high temperature stiffness, polymer clarity and speed of polymerization.
TRPGDA, available from Sartomer and Radcure, is a diacrylate monomer that, preferably, is included in the culll~osiLion because it provides good strength and hardness without adding bli~ -ess to the finished lens.
This material is also stiffer than TTEGDA.

TMPTA, available from Sartomer and Radcure, is a triacrylate monomer that. preferably. is included in the col.")oailion because it provides more crocclin~ing in the finished lens than the difunctional monomers.
TMPTA has a shorter backhone than TTEGDA and increases the high l."ll!J~.alul~ stiffness and hardness of the finished lens. Moreover, this material contributes to the prevention of optical distortions in the finished lens.
TMPTA also Cullll ibult:S tO high shrinkage during polymerization. The inclusion of too much of this material in 20 the most preferred colposilion may make the finished lens too brittle.

Certain of the monomers that are preferably utilized in the Culllpoàilioll of the present invention, such as TTEGDA, TRPGDA and TMPTA, include h~ ul;li.,s and have a yellow color in certain of their cc,llllllc.u;ally available forms. The yellow color of these monomers is preferably reduced or removed by passing them through 2S a column of alumina (basic) which includes ~ minllm oxide powder - basic. After passage through the alumina column, the monomers absorb almost no ultraviolet light. Also after passage through the alumina column dirr~.~,..c~s between monomers obtained from different sources are subst~rlti~lly elimin~t~l It is preferred, however, that the monomers be obtained from a source which provides the monomers with the least amount of i.nl,ul;li~s cont~in~d therein. The c~.,.,l,os;~ion preferably is filtered prior to polymerization thereof to remove 30 SI~IJ. - rl~d particles.

The composition of the present invention, preferably, may be prepared according to the following protocol. Ap~JIu~Jl;ale amounts of HDDMA, TTEGDA, TMPTA and TRPGDA are mixed and stirred thoroughly, preferably with a glass rod. The acrylate/methacrylate mixture may then be passed through a purification column.
A suitable purification column may be disposed within a glass column having a fitted glass disk above a teflon stopcock and having a top reservoir with a capacity of ap,ulu~dlllalely 500 mi and a body with a diameter of 22 mm and a length of about 47 cm. The column may be prepared by placing cn the fitted glass disk alJ~JIu~illlh~ly 35 g. of activated alumina (basic), available from ALFA Products~ Johnson Matthey, Danvers, MA

CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 in a 60 mesh form or from Aldrich in a 150 mesh form. Approximately 10 g. of an inhibitor remover (hydroquinone/methylester remover) available as HR-4 from Scientific Polymer Products. Inc.. Ontario, NY then may be placed on top of the alumina and, finally, appruxi---ately 35 g. of activated alumina (basic) may be placed on top of the inhibitor remover.
S
Approximately 600 g. of the acrylate/methacrylate mixture may then be added above the column packing. An o~ u-~ of 2-3 psi may then be applied to the top of the column resulting in a flow rate of a~,l"oAi---ately 30 to 38 grams per hour. Parafilm may be used to cover the junction of the column tip and the receiving bottle to prevent the infiltration of dust and water vapor. The acrylate/methacrylate mixture, preferably, 10 may be received in a container that is opaque to ultraviolet radiation.

An a~J~Jlu~Jlial~ amount of bisphenol A bis(allyl call~ lal~) may then be added to the acrylate/methacrylate mixture to prepare the final monomer mixture.

An a~JIJlu~lial~ amount of a photoinitiator may then be added to the final monomer mixture. The final monomer mixture, with or without photoinitiator, may then be stored in a container that is opaque to ultraviolet radiation.

An a~JIJIu~JI;dte amount of a dye may also be added to the final monomer mixture, with or without 20 photoinitiator.

After edging, the ultraviolet light cured lenses of the present invention dc,llùllsllal~ excellent organic solvent resistance to acetone, methylethyl ketone, and alcohols.

For best results, both the casting surfaces 86 and non-casting surfaces 88 of the mold members 78 are finished to optical quality. For instance, a wave on the non-casting surface 88 may be reproduced in the finished lens as a result of the distortion of the incident light.

Mold markings cause dilT~.~,n~iàl light intensity cc n~ innc under the marking, even when the mark is on 30 the non-casting surface 88 of the mold members 78. The fully exposed region of the lens will tend to be harder, and the lens may have stresses because of this. The portion of the lens under the mark will also tend to be weaker at the end of the curing period. This effect has been observed and may cause ~ lldtul~ release or induce cracking.

Mold defects at the edges interfere with the sealing conditions and frequently induce ~ .llalul~ release.

It is believed that as the reaction proceeds, the heat ~ ,.a~ed tends to reduce the adhesion between the shrinking lens and the mold face. This reduction in adhesion tends to cause the lens to pull away from the mold.
In high c u~ ~atul~; (i.e. high power) lenses this problem tends to be even more prono~nced because of two factors:

CA 022~1649 1998-10-13 WO 97/39880 PCTrUS97/06641 (I) these lenses have more thickness and thus more material that is generating heat (which thus speeds up the reaction and generates more heat), and (2) these lenses have a greater thickness dirr~ ."ial between the thick and thin portions of the lens, which tends to cause stress on the molds due to dirrc-~ ial shrinkage. It is also possible that the L~ p"lalul~i, generated relatively deep inside a thick lens may cause some vaporization of the monomer.
5 The vaporized monomer may then migrate to the lens/mold interface, breaking the vacuum between the two.

Because of the problem of p~t.lla~ule release, preferably high power lenses are cured to maintain adhesion to the molds. Preferably the molds flex and sacommodate stress.

10 l~lcr~,.ably the cooling fluid used is air at a te,l",~.. d~ul~; of less than 50~C. The fluid may be beiow 0~C, however in a preferred embodiment the fluid was at a ~ ,.aLul~ of between 0~C and less than 20~C, preferably about 0- 15~C, more preferably about 0- 10~C, more preferably still about 3-8~C. In one preferred embodiment the fluid temperature was about 5~C. As shown in Figure 9, a lens forming apparatus 300 for making a plastic lens may include a cooler 312 for supplying cool fluid to the àp,ua-aLuS 300 via conduit 314. The fluid may be 15 supplied to the apparatus 300 and then .lis, ha~ ,d via conduit 320. The fluid discharged via conduit 320 may be vented via conduit 318 or it may alternately be recirculated via conduit 316 to the cooler 312. The cooler 312 preferably includes a Neslab CFT-50 wdt~,./a--LirlL~,ze chiller (Newington, N.H., U.S.A.). A Neslab-built blower box designed for a minimum temperature of 3~C and 8 cubic feet (about 0.224 cubic meters) per minute of air per air distributor 94 was used with the chiller. The blower box included a heat exchanger coil through which chilled 20 water was circulated, a blower, and a plenum-type arrangement for supplying air to the conduit 314.

If lenses are produced with cf~ntin~ c UV light without any mold cooling, the t~llpc~atule of the mold-lens assembly may rise to above 50~C. Low diopter lenses may be prepared in this fashion, but higher plus or minus diopter lenses may fail. Certain lenses may be made by controlling (e.g., cooling) the tc~ aLulc of the 25 lens material during cure with circulating uncooled fluid (i.e., fluid at ambient L~ u~aLule~) The ambient fluid in these systems is directed towards the mold members in the same manner as described above. Circulating ambient l~."p~,.d1ure fluid permits m mlfsrh~re of a wider range of prescriptions than msn~f:~tn~e of the lenses without any mold cooling at all.

Most polymerization factors are i,~t~,.lclaL~d. The ideal ~c.lllJ.,.dlul~ of polymerization is related to the diopter and thickness of the lens being cast. Thermal mass is a factor. Lower tc.lll,.,.dlulcs (below about 10~C) are preferred to cast higher + or - diopter lenses when using co..lil. ..~uc UV light. These lower tc.l~ ,.atul~ tend to permit an increase in photoinitiator collce~l~la~ion~ which in turn may speed up the reaction and lower curing time.
P~iculh~g premature release when using crntinllouc UV light is also sc,lll~,~.llal d~ t upon the flowrates of cooling fluid, as well as its ~ ,.d~ulc. For instance, if the L~ C~aLulc of the cooling fluid is de.,,cascd it may also be possible to decrease the flowrate of cooling fluid. Similarly, the disadvantages of a higher lc.,,~c.~ulc cooling fluid may be somewhat offset by higher flowrates of cooling fluid.

CA 022~1649 1998-10-13 W097/39880 PCTrUS97/06641 In one embodi..~,..l the air flow rates for a dual distributor system (i.e.. an air distributor above and below the lens co~ ,n~ilion) are about 1-30 standard cubic feet ("scf~') (about 0.028 - 0.850 standard cubic meters) per minute per diallibu~ more preferably about 4-20 cubic feet (about 0.113-0.566 standard cubic meters) per minute per distributor. and more preferably still about 9- 15 (about 0.255-0.423 standard cubic meters) cubic feet per minute per distributor. "Standard conditions," as used herein, means 60 ~F (about 15.556~C) and one atmosphere pressure (about 101.325 kilopascals).

The thickness of the glass molds used to cast polymerized lenses may affect the lenses produced. A
10 thinner mold tends to allow more efficient heat transfer between the polymerizing material and the cooling air, thus reducing the rate of ~ alule release. In addition, a thinner mold tends to exhibit a greater p-u~ ily to flex. A thinner mold tends to flex during the relatively rapid differential shrinkage between the thick and thin portions of a poly...e.i,~d lens, again reducing the incitlenre of premature release. In one embodiment the furst or second mold members have a thickness less than about 5.0 mm~ preferably about 1.0-5.0 mm, more preferably 15 about 2.0-4.0 mm, and more still about 2.5-3.5 mm.

"Front" mold or face means the mold or face whose surface ultimately forms the surface of an eyeglass lens that is furthest from the eye of an eyeglass lens wearer. "Back" mold or face means the mold or face whose surface ultimately forms the surface of an eyeglass lens that is closest to the eye of a eyeglass lens wearer.
In one embodiment the lens forming material is preferably cured to form a solid lens at relatively low aiul~, relatively low continuollc ultraviolet light intensity, and relatively low photoinitiator cc,nce..I~alions.
Lenses produced as such generally have a Shore D hardness of about 60-78 (for the preferred co-.,po~iIions) when cured for about 15 minutes as described above. The hardness may be improved to about 80-81 Shore D by 25 postcure heating the lens in a conventional oven for about 10 minutes, as described above.

In a preferred embo~ n~ UV light may be provided with mercury vapor lamps provided in UVEXS, Inc. Model CCU or 912 curing chambers (Sunnyvale, CA, U.S.A.).

In an alternate method for making a lens, the desired curvature (i.e., power) of the lens may be varied using the same molds, but with different light distributions. In this manner one mold may be used to prepare different lenses with different curvatures. The method includes the steps of: (I) placing a polymerizable lens forming material in a mold cavity defined in part between a first mold member and a second mold member, and wherein the cavity defines a theoretical curvature that is different from the desired curvature, (2) directing 35 ultraviolet rays towards at least one of the first and second mold members, and wherein the ultraviolet rays are directed towards the first or second mold member such that the material cures to form a lens with the desired curvature, and (3) cont~tinlv fluid against the first or second mold member to cool the first or second mold member. The resulting lens curvature may vary depending on the way the ultraviolet light is directed towards the CA 022~1649 1998- lo- 13 WO 97t39880 PCT/US97/06641 first or second mold members. That is, by varying the relative intensity of the light across the lens material radii, it is possible to vary the curvature of the resulting lens.

s Formulation: 17% Bisphenol A BisAllyl Carbonate 10% 1,6 llc,~.. ediol dimethacrylate 20% Trimethylolpropane triacrylate 21 % Tetraethyleneglycol diacrlate 32% Tripropyleneglycol diacrlyate 0.012% I Hydroxycyclohexyl phenyl ketone 0.048 Methylbenzoylformate <lOPPMHy.l.u4uinolle & Methylethylhydroquinone Hydroquinone and Methylethylhydroquinone were stabilizers present in some of the diacrylate andlor triacrylate compounds obtained from Sartomer. Preferably the amount of stabilizers is minimi7Pd since the stabilizers affect the rate and amount of curing. If larger amounts of stabilizers are added, then generally larger arnounts of photoinitiators must also be added.
~0 Light Condition: mW/cm2 measured at plane of sample with Spectroline DM 365N Meter from Specl-u.,ics Corp. (Westbury, N.Y.) Center Edge Top: 0.233 0.299 Bottom: 0.217 0.248 Air Flow: 9.6 standard cubic feet ("CFM") per manifold - 19.2 CFM total on sample ~0 Air Tc~ e.d~u~e: 4.4 degrees Centigrade CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 Molds: 80 mm diameter Corning #8092 glass Radius Thickness Concave: 1 70.S9 2.7 Convex: 62.17 5.4 Gasket: General Electric SE6035 silicone rubber with a 3 mm thick lateral lip Aim~ncjon and a vertical lip dimension sufficient to provide an initial cavity center thickness of 2.2 mm.
Filling: The molds were cleaned and assembled into the gasket. The mold/gasket assembly was then te.ll~.olalily positioned on a fixture which held the two molds pressed against the gasket lip with about 1 kg. of pressure. The upper edge of the gasket was peeled back to allow about 27.4 grams of the monomer blend to be charged into the cavity. The upper edge of the gasket was then eased back into place and the excess monomer was ~a~ ullled out with a small aspirating device. It is ~ f~,lable to avoid having monomer drip onto the no"~ ~ainP surface of the mold because a drop tends to cause the ultraviolet light to become locally focused and may cause an optical distortion in the final product.

20 Curing: The sample was hl " i for fifteen minutes under the above conAitir~nc and removed from the "FC-104" curing chamber (i.e., the chamber shown in Figures 14 and 15). The molds were sep~al~,d from the cured lens by applying a sharp impact to ~he junction of the lens and the convex mold. The sample was then postcured at 110 ~C in a conventional gravity type thermal oven for an ~AhiorlQI ten minutes, removed and allowed to cool to room temperature.

Results: The resulting lens measured 72 mm in diameter, with a central thickness of 2.0 mm, and an edge thickness of 9.2 mm. The focusing power measured ~5.05 diopter. The lens was water clear ("water-white"), showed negligible haze, exhibited total visible light trQncmiisio n of about 94%, and gave good overall optics. The Shore D hardness was about 80. The sample withstood the impact of a 1 inch steel ball dropped from fifty inches in acco..lallce with AI~ISI 280.1-1987, 4.6.4 test ~ ced CA 022~1649 1998-10-13 WO 97/39880 PCT/US97tO6641 ADDITIONAL IMPROVEMENTS

POSTCURE WITH AN OXYGEN BARRIER ENRICHED WITH PHOTOINITIATOR

In certain applications, all of the lens forming cc .. ~,oailion may fail to completely cure by exposure to ultraviolet rays when forming the lens. In particular, a portion of the lens forming composition plu~ill,a~c the gasket often remains in a liquid state following formation of the lens. It is believed that the gaskets are often soll~ llal p~,.",edl)le to air, and, as a result~ oxygen p.,~ them and contacts the portions of the lens forming material that are l,lu~i,.,ale the gasket. Since oxygen tends to inhibit the photocuring process, portions of the lens 10 forming co",po~ilion proximate the gasket tend to remain uncured as the lens is formed.

Uncured lens forrning CU~YUail;On PlUAhlldtt: the gasket is a problem for several reasons. First, the liquid lens forming composition leaves the edges of the cured lens in a sulllc~.llal sticky state. which makes the lenses more difficult to handle. Second, the liquid lens forming cc ..l,,.oa-lion is SOIll~ lldt difficult to ~ pl~: Iy 15 remove from the surface of the lens. Third, liquid lens forming composition may flow and at least partially coat the surface of lenses when such lenses are removed from the molds. This coating is difficult to remove and makes application of scratch resistant coatings or tinting dyes more difficult. This coating tends to interfere with the interaction of scratch resistant coatings and tinting dyes with the cured lens surface. Fourth, if droplets of liquid lens forming material form, these droplets may later cure and form a ridge or bump on the surface of the 20 lens, especially if the lens undergoes later postcure or scratch resistant coating proceiscs. As a result of the above p.ubl c often lenses must be tediously cleaned or recast when liquid lens forming co---posilion remains after the lens is formed in an initial cure process.

The problems outlined above can be mitigated if less liquid lens forming composition remains 25 proximate the gasket after the lens is formed. One method of lessening this "wet edge'- problem relates to increasing the amount of photoinitiator present in the lens forming composition (i.e., increasing the amount of pllul()illialo~ in the lens forming culllpu~i~ion above about 0.15 percent). Doing so, however, tends to create other problems. Specifically, i--c-cdsed IJhotoillili..~l levels tend to cause exotherrnic heat to be released at a relatively high rate during the reactiûn of the culllpoailiun. P~-,.,,aIu-c release and/or lens cracking tends to result. Thus it is 30 believed that lower amounts of pllulo .liIia~n are preferred.

The wet edge problem has been addressed by a variety of methods described in U.S. patent application serial number 07/931,946. Such methods relate to r.,.l.~ . il-g the gasket and applying either an oxygen barrier or a photoinitiator enriched liquid to the exposed edge of the lens. The lens is then re-irradiated with s~fficient 35 ultraviolet light to completely dry the edge of the lens prior to demolding.

An embodiment of the invention relates to improving the methods described in the 07/931,946 application. This embodiment relates to combining an oxygen barrier with a photoinitiator. Specifically, in one embodiment an oxygen barrier 970 (e.g., a thin strip of polyethylene film or the like as shown in Fig. 12) is CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 Pnlbed~l~d or hll~ làt~,d with a photoinitiator 972. The oxygen barrier is then wrapped around the edge of a cured lens which is still encased between two molds (but with the gasket removed). While still "in the mold," the lens is then exposed to ultraviolet light, thereby drying its edge. An improvement of this method over those previously disclosed is that there is a ci~nifir~nt reduction in the UV dosage necessary to bring the lens edge to 5 dryness.

A plastic oxygen barrier film which includes a photoinitiator may be made by: (a) immersing a plastic film in a solution cc""prisi"g a phoLo ~ , (b) removing the plastic film from the solution, and (c) drying the plastic film. The solution may include an etching agent. Preferably a surface of the plastic film is etched prior to 10 or while i...,..c.~i"g the plastic film in the solution.

In one example, thin strips (e.g., about 10 mm wide) of high density polyethylene film (a~ploxilllàlely 0.013 mm thick) may be soaked in a solution of 97% acetone and 3% Irgacure 184 (a photoinitiator commercially available from Ciba Geigy located in Farming~ . New Jersey) for about five minutes. The polyethylene film 15 may be obtained from Tape Solutions, Inc. (Nashville~ Tennessee). In a more preferred embodiment, 0.5% Byk 300 (a flow agent collllln,.~;àlly available from Byk Chemie located in Wallingford, ConnPcticut) may be included in the soaking solution. It is believed that xylene in the Byk 300 tends to etch the surface of the film and make the film more receptive to absGl~ un of the Irgacure 184. In a still more preferred ~ ~--bo.l; -- ~.1 the treated polyethylene strips may be dipped in acetone for about ten seconds to remove excess Irgacure 184. Excess 20 ~h~ iti~tf, may be seen as a white powder which coats the strips after drying. In either case, the strips are then allowed to air dry before applying them to the edge of the lens as described above.

In one alternate embodiment of the invention, a plastic eyeglass lens may be made by the following steps: (I) placing a liquid polymerizable lens forming composition in a mold cavity defined by a gasket, a first 25 mold member, and a second mold member; (2) directing first ultraviolet rays toward at least one of the mold members to cure the lens forming cc",.posilion so that it forms a lens with a back face, edges, and a front face, and wherein a portion of the lens forming co~nrocition ~uJ-illlale the edges of the lens is not fully cured; (3) removing the gasket to expose the edges of the lens; (4) applying an oxygen barrier which includes a photoinitiator around the exposed edges of the lens such that at least a portion of the oxygen barrier phot~ dlul 30 is proximate lens forming cu...~,G ,ilion that is not fully cured; and (5) directing second ultraviolet rays towards the lens such that at least a portion of the oxygen barrier phulu;llilialùl initiates reaction of lens forming cu.~ n while the oxygen barrier s-~b~ liy prevents oxygen from outside the oxygen barrier from contr~ting at least a portion of the lens forming cc.~pss;~ ;u-- The first and second ultraviolet rays may (a) be at the same or different wavelengths and/or ;..~ u~ s, (b) be contin~ons or pulsed, and (c) be from the same or different light source.
A purpose of the steps 4-5 is to reduce the amount of uncured liquid lens forming co,.lpo~ilion that is present when the lens is se~,a. ~ed from the molds and/or gasket. It has been found that reducing the amount of liquid lens forming c~...posilion is especially ad~,a.,l..geuu~ if such reduction occurs before the molds are separated from the cured lens. Sc~)~dlillg the molds from the cured lens may cause uncured liquids to at least CA 022~1649 1998-10-13 partially coat the lens faces. This coating occurs because uncured liquid lens forming c.. pn~;lion tends to get swept over the faces when the molds are separated from the lens. It is believed that curing of the lens tends to create a vacuum between the lens and the mold. Air may sweep over the mold faces to hll this vacuum when the molds are separated from the lens. This air tends to take liquid lens forming cu~l-poai~ion into the vacuum with it.

In step 4 above, an oxygen barrier which includes a photoinitiator is applied to the edges or sides of the lens after the gasket is removed. r~,f~.ably this oxygen barrier is applied while the lens are still attached to the molds. In an altemate embodiment this oxygen barrier is also applied to the edges or sides of the molds at the same time it is applied to the sides of the lens. In a preferred embodiment. the sides of the lenses are first cleaned 10 or wiped to remove at least a portion of the uncured liquid lens forming cornpositiorl before the oxygen barrier is applied.

After the oxygen barrier is applied, second ultraviolet rays are directed towards the lens. After the second ultraviolet rays are directed toward the lens, at least a portion of the liquid lens forming culll?oaiLion 15 which was not cured in the initial cure steps is cured. It is believed that the photoinitiator embedded in the oxygen barrier facilitates faster and more complete curing of the uncured lens forming c- ,..po.il iun. As such, less second ultraviolet rays are employed, thereby lessening the time and energy required in this step. Furthermore, lens quality tends to be enhanced since a lower application of the second ultraviolet rays tends to reduce the potential for lens yellowing.
In a preferred embo~lim~nt ~ ly all of the remaining liquid lens forming composition is cured after the second ultraviolet rays are directed toward the lens. More preferably, the lens is subst~nti:~lly dry after the second ultraviolet rays are directed towards the lens.

After the second ultraviolet rays are directed toward the lens. the lens may then be demolded. The lens may then be tinted. After the lens is demolded, a scratch resistant coating may be applied to the lens. In one embodiment, a scratch resistant coating is applied to the demolded lens by applying a liquid scratch resistant coating co...l.o,i~ion to a face of the lens and then applying ultraviolet rays to this face to cure the liquid scratch resistant coating to a solid.
In an embodiment, the intensity of the ultraviolet rays applied to the face of the lens to cure the liquid scratch resistant coating col~po~;l;r)n to a solid is about 150-300 mW/cm2 at a wave length range of about 360-370 nm, and about 50-150 mWlcml at a wave length range of about 250-260 nm. The lens may be heated after removal from the molds, or after application of a scratch resistant coating to the lens.
In a preferred embodiment, the total intensity of the first ultraviolet rays directed toward the mold members is less than about 10 mW/cm2 CA 022~1649 1998-10-13 ln an embo-limPnt the intensity ofthe second ultraviolet rays directed toward the lens is about 150-300 mW/cm~ at a wave length range of about 360-370 nm, and about 50- 150 mW/cm' at a wave length range of about 250-260 nm. Preferably the second ultraviolet rays are directed towards the lens for less than about I minute.

In a preferred embodiment, the above method may further include the Ad~ition-AI step of directing third ultraviolet rays towards the lens before the oxygen barrier is applied. These third ultraviolet rays are preferably - applied before the gasket is removed. Preferably, the second and third ultraviolet rays are directed toward the back face of the lens (as stated above, the second and third ultraviolet rays are preferably applied while this lens is in the mold cavity). The third ultraviolet rays are preferably about the same range of intensity as the second ultraviolet rays. The same a~palalus may be used for both the second and third ultraviolet rays.

In a preferred embodiment, the method described above also includes the step of removing the oxygen barrier from the edges of the lens.

The second and third ultraviolet rays may be repeatedly directed towards the lens. For instance~ these ultraviolet rays may be applied via a light assembly whereby the lens passes under a light source on a movable stand. The lens may be repeatedly passed under the lights. Repeated exposure of the lens to the ultraviolet rays may be more beneficial than one ~,.ulu.-gcd exposure.

Preferably the oxygen barrier includes a film, and more preferably a plastic, flexible, and/or elastic film. In addition, the oxygen barrier is preferably at least partially Ilalls~Jalc.lt to ultraviolet rays so that ultraviolet rays may penetrate the oxygen barrier to cure any remaining liquid lens forming cull.~oai~ion.
~ef~lably the oxygen barrier is stretchable and self-sealing. These features make the film easier to apply.
~cl~.ably the oxygen barrier is resistant to penetration by liquids, thus keeping any liquid lens forming co--l,ûs;'inn in the mold assembly. Preferably, the oxygen barrier includes a thermoplastic comros~ n. It is A~ln~ d that many different oxygen barriers may be used (e.g., saran wrap, polyethvlene, etc.). In one preferred embodiment, the film is "Parafilm M Laboratory Film" which is available from American National Can (Greenwich, CT, U.S.A.). The oxygen barrier may also include AAII-rninl-m foil.

Preferably the oxygen barrier is less than about 1.0 mm thick. More preferably the oxygen barrier is 0.01 to 0.10 mm thick, and more preferably still the oxygen barrier is less than 0.025 mm thick. If the oxygen barrier is too thick, then it may not be readily stretchable andlor conformable, and it may not allow a sllffiri~Pnt amount of light to pass through it. If the oxygen barrier is too thin, then it may tend to tear.

An a~ alalU~ for applying a scratch resistant coating co~ ,(,aiIion to a lens and then curing the scratch resistant coating cul"~,o~i~ion is described in U.S. patents 4,895,102 to Kachel et al. and 3,494,326 to Upton (both of which are illcul~JulaIcd herein by ,c[~.e"ce). In addition, the a~JIJalalu~ schPmAAficAlly shown in Figure 10 may also be used to apply the scratch resistant coating.

CA 022~1649 1998-10-13 Figure 10 depicts an ap~Jalalus 600 with a first chamber 602 and a second chamber 604. This a~ ala~,, can be used to apply scratch resistant coating to a lens, to postcure a lens, or to apply ultraviolet light to a lens mold assembly. The first chamber 602 includes an opening 606 through which an operator can apply lenses and lens mold assemblies to the lens holder 608. Lens holder 608 is partially surrounded by barrier 614.
First chamber 602 may include an insrec~ion light 610, and an opening 618 in the floor of the chamber.

Lens holder 608 is attached to device 612. It is envisioned that device 612 may be a spinning device which would permit the alJ~al alu l 600 to be used to apply scratch resistant coatings to lenses. In such case device 612 would connect directly to lens holder 608 through a hole in the bottom of barrier 614. In a preferred 10 embodiment, however, device 612 just connects the lens holder 608 or barrier 614 to moving device 616. It has been found that a separate spinner (not shown) may provide better results for application of scratch resistant coatings to lenses.

~f~,.ably barrier 614 has an interior surface that is made or lined with an absGll,al,t material such as 15 foam rubber. Preferably this absvl ba.,l material is disposable and removable. The absv. l aill material absorbs any liquids that fall off the lens holder 608, keeping in the interior surface of the barrier 614 clean.

In an emho~iim~nt~ shutter 621 is used to inhibit the ultraviolet light from light assembly 622 from c p barrier 614. It is preferred that lens holder 608 be exposed to the ultraviolet light from light assembly 20 622 while shutter 621 blocks at least a portion of the light from c~ ; g barrier 614. Shutter 621 may also inhibit any liquid lens forming material that falls from lens holder 606 from curing on barrier 614. Shutter 621 thus tends to inhibit the formation of flakes on the surface of barrier 614. Shutter 621 operates after barrier 614 drops, thus shielding barrier 614 while allowing UV light to contact the sample.
In an embodi"lc.,l, apparatus 600 may be used to apply a precoat to lens before the hardcoat is applied.
The precoat may serve to increase the "wettability" of the surface to which the hardcoat is to be applied. A
L,lalll has been conventionally employed for this purpose, however SUI P~a~lallt~ tend to affect the volatility and flow characteristics of lens coatings in an unfavorable manner. The precoat may include acetone andlor Byk 300.
Upon even distribution of the hardcoat onto a lens in lens holder 608, the coating may be wiped near the edges of 30 the lens to prevent the rul-aliuof excessive flakes during curing.

In another e.llbo~ , the precoat and hardcoat are .I;~I-il,ut~,d onto lens holder 608. Ultraviolet light is directed toward the coatings at least until a gel is formed. A lens forming material may be placed on top of the gel and cured.
Second chamber 604 includes an opening 620 in its floor. It also includes an ultraviolet light assembly 622, which may include multiple lights and a light reflector.

CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 The apparatus 600 includes an air filtering and distribution system. Air is pulled into a chamber 628 by fans 626 through a filter 624 (the quantity and locations of the fans and filters may vary). The filtered air is distributed by the fans 626 throughout chambers 602, 604, and 617. Air flows from point 613 to point 615 via air ducts (not shown) to reach chamber 617. The te.~ .,.dlul~ of the lights and/or the second chamber may be controlled by turning various fans 629 on and off as needed to suck air out of chamber 604. Air is di~ ;l,ut. d from chamber 617 through holes 636 that are pro~ ,al~ the lower part of the opening 606 in the first chamber 602. Air is also sucked by fans 627 from the first chamber 602 to chamber 630 through holes 634 that are proximate the top part of the opening 606 in the first chamber 602. This arr~n~PnlPn~ tends to prevent contaminants from entering first chamber 606. Air is discharged from chamber 630 to the surroundings via fans 10 627.

During use a lens or lens mold assembly may be placed on the lens holder 608. A button can be pressed, causing the moving device 616 to move device 612, lens holder 604, and the barrier 614 so that they are under the opening 620 in the second chamber 604. Light is thus applied to the lens or lens mold assembly from 15 light assembly 622. After a set period of time~ the moving device 616 moves everything back to a location underneath the opening 618 in the first chamber 602.

The lens holder 608 may include a suction cup connPctPd to a metal bar. The concave surface of the suction cup may be attachable to a face of a mold or lens, and the convex surface of the suction cup may be 20 attached to a metal bar. The metal bar may be attachable to a lens spinner.

The lens holder may also alternately include movable arms and a spring assembly which are together operable to hold a lens against the lens holder with spring tension during use.

In an alternate method of the invention, a lens may be cured between two mold members. The gasket may be removed and any remaining liquid lens composition may be removed. At this point a mold member may be applied to a ~II,s~ lly solid conductive heat source. Heat may then be conductively applied to a face of the lens by (a) conductively transferring heat to a face of a mold member from the conductive heat source, and (b) conductively Irall~rtll i,.g heat through such mold member to the face of the lens. The oxygen barrier enriched 30 with phu~u may then be applied, and second ultraviolet rays may be directed towards the lens to cure the n ~ ~ Iens forming composition.

OXYGEN BARRUER EXAMPLE#1 A liquid lens forming c~ po~ilion was initially cured as in a process and apparatus similar to that specified in Example 1. The Cu~ ,GSiIil)ll was suhst~ti~lly the same as specified in E~xample 1, with the exception that hydroquinone was absent, the cullc~lllalion of methylethylhydroquinone was about 25-45 ppm, the conc~ raIion of I hydroxycyclohexyl phenyl ketone was 0.017 percent, and the conc~ aIion of methylbenzoylformate was 0.068 percent. The co"",o~ilion u.,d~ ..,.,I the initial 15 minute cure under the "Ist CA 022~1649 1998-10-13 W O 97139880 PCT~US97/06641 UV." The appalaLus was sllbst ntially the same as described for the above Example 1, with the following exceptions:

1. The air flowrate on each side of the lens mold assembly was ectin~tl d to be about 18-20 cubic feet per minute.

2. The apparatus was modified in that air flowed to and from the openings 96 and orifices 98 (which were themselves s ~ lly nnrh~n~ed) through a duct behind the lens formingchamber, instead of through pipes (e.g. pipe 12 in Figure 5). Fe~Pnti~lly plenum portion 95 was expanded so that the walls of the chamber are the walls of the plenum portion 95. Figure 14 depicts a front view of this lens curing ap~ala~us 800. Air in apparatus 800 flows from the orifices 98~ over the lens mold assembly 802, through ducts 804, through fan 806, through heat exchanger 808, and then through ducts 810 and back to orifices 98 via air return conduits 824 (shown on Figure 15). Figure 14 also shows a water chiller 812 which cools water and then sends it through conduits 814 and through heat ~yr~ nE~pr 808. Figure 14 also shows lights 816 and frosted glass 818. The chamber 820 surrounding lights 816 is not com~r~- d to the chamber 822 around the mold assembly 802. In this manner chilled air from orifices 98 does not contact and cool the lights 816 (such cooling tends to cause excessive changes in light output). The chamber 820 is cooled by fans (not shown) which turn on and off ~lçpçnfling on the t~ alule of the surface of the lights 816. Figure 15 shows a side view of J~ dlU~ 800.

3. The air flowrate in and out of the chamber surrounding the lights was varied in acco-.ldnce with the surface ~ alulc of lights. The air flowrate was varied in an effort to keep the te~ .,.aL~Ic on the surface of one of the lights between 104.5 ~ F and 105 ~ F.

4. The ultraviolet light output was controlled to a set point by varying the power sent to the lights as the output of the lights varied.

305. Frosted glass was placed between the lights and the filters used to vary the intensity of the ultraviolet light across the face of the molds. Preferably the glass was frosted on both sides.
The frosted glass acts as a diffuser between the lights and these filters. This frosted glass tended to yield better results if it was placed at least about 2 mm from the filter, more pl~r~lably about 10-15 mm, more preferably still about 12 mm, from the filter. Frosted glass was found to dampen the effect of the filters. For instance, the presence of the frosted glass reduced the systems' ability to produce different lens powers by varying the light (see Example I and Figure 1).

CA 022~1649 1998-10-13 W097t39880 PCTrUS97/06641 6. In Figure 3 the center lights 40 are shown in a triangular arrangement when viewed from the side. These lights were rearranged to provide an in-line allallg~,.llclll.

After initial cure, the lens mold assembly was removed from the curing chamber. The lens mold 5 assembly included a lens surrounded by a front mold, a back mold, and a gasket between the front and back molds (see, e.g., the assembly in Figure 6).

At this point the protocol in Example I stated that the lens was demolded (see above). While demolding at this point is possible, as stated above generally some liquid lens forming composition remained, 10 especially in areas of the iens proximate the gasket. Therefore the lens was not demolded as stated in Example 1.
Instead, the gasket was removed, liquid lens forming co...?o~iIion was wiped off the edges of the lens, and a layer of oxygen barrier (Parafilm M) with photoiniti~tor was wrapped around the edges of the lens while the lens was still between the molds. The Parafilm M was wrapped tightly around the edges of the lens and then stretched so that it would adhere to the lens and molds (i.e. in a manner similar to that of Saran wrap). The lens mold 15 assembly was then placed in apparatus 600 so that the back face of the lens (while between the molds) could then be exposed to second ultraviolet light.

This second ultraviolet light was at a s~lhst~ ltiolly higher intensity than the initial cure light, which was directed at an intensity of less than 10 mW/cm2. The mold assembly was passed in and out of second chamber 20 604 in Figure 10 (i.e., a UVEXS Model 912) when the light was set at the high setting. Passing in and out of the chamber took about 22 seconds. The total light energy applied during these 22 seconds was about 4500 millijoules per square c~ .li,..~t ("mJ/cm2").

Preferably the total light energy applied per pass under the second and third ultraviolet ray lights was 25 in the range of about 500-10,000 mJ/cm', more preferably about 3000-6000 mJ/cm', and more ~JIerelably still 4000-5000 mJ/cm'. Light energy may be varied by varying the time of exposure, or the intensity of the light.
Light energy was measured with a Model IL390B Light Bug from International Light, Inc. (Newburyport, MA, U.S.A.). The total light energy ~ the total amount of ultraviolet light over the range of 250 to 400 nm.

It has been found that applying ultraviolet light at this point helped to cure some or all of the remaining liquid lens forming c-~"l,o~ ion. The second ultraviolet light step may be repeated. In this example the second ultraviolet light step was repeated once. It is also possible to expose the front or both sides of the lens to the second ultraviolet light.

After the second ultraviolet light was applied, the mold assembly was allowed to cool. The reactions caused by exposure to ultraviolet light are exothermic. The ultraviolet lights also tend to emit infra-red light which in turn heats the mold assembly. The lens was then demolded. The demolded lens was 5~h5t~ tiolly drier and harder than lenses that are directly removed from mold assemblies after the initial cure step.

CA 022~1649 1998-10-13 W097/39880 PCTrUS97/06641 OXYGEN BARRIER EXAMPLE #2 The protocol of Oxygen Barrier Example #I was repeated except that prior to removal of the gasket the lens mold assembly was positioned so that the back face of the lens was exposed to third ultraviolet light. In 5 this case the third ultraviolet light was at the same intensity and for the same time period as one pass of the second ultraviolet light. It has been found that applying third ultraviolet light at this point helped to cure some or all of the r.,.--ai--i--g liquid lens forming composition so that when the gasket was removed less liquid lens forming cc,...?osiIion was present. All of the rPm-Aining steps in Oxygen Barrier Example #I were applied, and the resultant lens was ,ul~ "l;ally dry when removed from the molds CONDUCTIVE HEATING

An embodiment of the invention relates to po~ n i..g a polymerized lens co.,l-; Pd in a mold cavity by applying conductive heat to at least one of the molds that form the mold cavity, prior to demolding the lens.
More particularly, one c.-.bo~ of the invention includes the following: (I) placing a liquid lens forming cu..,l,o~ilion in a mold cavity defined by at least a first mold member and a second mold member, (2) directing ultraviolet rays toward at least one of the mold members to cure the lens forming c~..-po~ilion so that it forms a lens with a back face, edges, and a front face, (3) applying a mold member of the mold cavity to a ~ lly solid conductive heat source; and (4) conductively applying heat to a face of the lens by (a) conductively transferring heat to a face of a mold member from the conductive heat source, and (b) conductively . ~ . i--g heat through such mold member to the face of the lens.

In an embodiment described as follows, a lens cured by exposure to ultraviolet light is further processed 25 by conductive heating Such conductive heating tends to enhance the degree of cross-linking in the lens and to increase the tintability of the lens. A lens forming material is placed in mold cavity 900 (illustrated in Fig. 19), which is defined by at least first mold member 902 and second mold member 904 Ultraviolet rays are directed toward at least one of the mold members, thereby curing the lens forming material to a lens Heat distributor 910 (shown in Fig. 16) may be adapted to .li~l. ;I,u~ conductive heat from conductive heat source 912 to at least one 30 mold member. Heat distributor 910 is preferably flexible such that at least a portion of it may be shaped to ,~ b~ ially conform to the shape of face 906 or face 907 of first mold member 902 or second mold member 904"~ c.,~ ly. Heat distributor 910 is preferably placed in contact with conductive heat source 912, and mold member 902 is placed on heat ~ I ib-llDI 910 such that face 906 of the mold member rests on top of the heat di .tfibulul 910. Heat di ,l, ib~llur 910 may be coupled to heat source 912. Heat is conductively applied to the heat 35 di~ ibu~ol 910 by the heat source 912. Heat is cond~lrted from the heat di~llibulul 910 through the mold member to a face of the lens. The heat .li~IlilJulDl may be shaped to ~cc~ odAIr face 906 of first mold member 902 or face 907 of second mold member 904 such that the heat is applied to front face 916 or back face 915 of the lens (showninFig. Il). Thet~...t,.,.dtulc of heatsource912maybe IL~ CS~IAIIC ally cc.,llullcd.

CA 022~1649 1998-10-13 In an embodiment~ hot plate 918 (shown in Fig. 17) is used as a heat source to provide conductive heat to the lens. A number of other heat sources may be used. In an embodiment~ heat d;all ibulo~ 910 may include cou,.t~,.alldpe 920. ColJ~ .al,a~,e 920 may be placed on top of the hot plate to distribute conductive heat from the hot plate. The cuullt~.~l.a~,c is preferably flexible such that at least a portion of it may aul~a~ lly conform to 5 the shape of an outside face of a mold member. The cou-,t-,.al-ape may be hemispherical and either convex or concave ~ ,. .,.l;..g upon whether the surface of the mold assembly to be placed upon it is convex or concave.
- For example, when the concave surface of the back mold is utili~ed to conduct heat into the lens assembly, a convex coullt~.alla~e is provided to rest the assembly on.

COun~.al,a~,c 920 may include a glass mold, a metal optical lap, a pile of hot salt and/or sand, or any of a number of other devices adapted to conduct heat from heat source 912. It should be understood that Figure 17 includes cu~ .laLions of a number of embodil,le.,la for illustrative purposes. Any number of identical or distinct co_ ahalJes may be used in combination on top of a heat source. In an embodiment, a cuullt~.alla~Jc includes a collL~ . 922 filled with particles 924. The particles preferably include metal or ceramic material. CoullLe.al~,c 15 920 may include heat diall ;bulo~ 910. A layer 914 of material may be placed over the COI".t~. ahapc 920 or heat dial,il,ulor 910 to provide slow, smooth, uniform heat con~ ti-)n into the lens mold assembly. This layer preferably has a relatively low heat conductivity and may be made of rubber, cloth, Nomex TM fabric or any other suitable material that provides slow, smooth, uniform con~llrtion.

In an embodiment, cuulll~.allalJc 920 includes layer 914 (e.g., a bag or container) filled with particles 924 such that the cou"t. ~al~ape may be conveniently shaped to conform to the shape of face 906 or face 907. In an emhod; - ~ 1, the coullt~.allà~Jc is essentially a "beanbag" that contains particles 924 and is conformable to the shape of a mold face placed on top of it. Particles 924 may include ceramic material, metal material, glass beads, sand and/or salt. The particles ~ el~bly facilitate conductive heat to be applied to face 906 or face 907 25 subst~nti~lly evenly.

In an emhorliml~nt, the cùulll~.allalJc 920 is placed on top of heat source 912 for a sufficient time for a portion of the coullL~ à"c to attain a ~ .aLul~ hsts~nti~lly near or equal to the t~ul~.dtul~ on the surface of the heat source. The cuuate.al,ape may then be "flipped over" such that the heated portion of the coull1~.alla~,c 30 that has a ~ ,.dlUlC; ~-~h~ ily near or equal to that of the surface of the heat source is exposed. A mold may be placed on top of the heated portion of the couut~,~alla~J~, and the coul,t~.al,ape is preferably co"~o",lcd to the shape of the face of the mold. In this manner, the rate of conductive heat transfer to the lens may begin at a Heat is preferably conductively transferred through the coL..Ielallà~)c and the mold face to a face of - the lens. The t~_lllp~.~ alule of the heated portion of the Coullt~,~ al,ape may tend to decrease after the mold is placed 35 onto the cou,lt~,.al,ayc.
-In an ~mhodi...l .~l heat .li,L- il,ulu, 910 may partially insulate a mold member from conductive heat source 912. The heat distributor preferably allows a gradual, uniform transfer of heat to the mold member. The heat diaLI ibulol iS preferably made of rubber and/or another suitable material. The heat diall ;bulo. may include CA 022~1649 1998-10-13 cuu~ al,apes of various shapes (e.g., hrmicphprically concave or convex) and sizes that are adapted to contact and receive mold members.

In an ~ ~..l~od;. c..~, hot plate cover 930 (shown in Fig. 8) is used to distribute conductive heat to face 906 S of mold member 902. Cover 930 is adapted to rest directly upon hot plate 918 (or any other heat source). Cover 930 preferably includes portion 932, which is 5 '~ ~ ' lly conformed to the shape of face 906. Portion 932 preferably includes a convex surface or a concave surface (not shown) adapted to receive face 906. Portion 932 is preferably made of rubber and causes slow, uniform transfer of conductive heat to face 906. In an ~ ...bodi...c.ll, a hot plate cover having concave ind~ tio ~c sllh~t~nti~lly conformed to the shape of face 907 is 10 used to distribute heat through a mold member to a lens.

In an embodiment, heat is conductively applied by the heat source to only one outside face of one mold member. This outside face may be face 906 or face 907. Heat may be applied to back face 915 of the lens to enhance crosslin~ing and/or tintability of the lens material proximate to the surface of the back face of the lens.
In a preferred l .,-bod;...~ , thc. .~o.l ~ ir~lly controlled hot plate 918 is used as a heat source. Glass optical mold 928 is ~ f~. ably placed convex side up on hot plate 918 to serve as a coul~ aha~c. The glass optical mold preferably has about an 80 mm diameter and a radius of curvature of about 93mm. Rubber disc 929 may be placed over this mold 928 to provide uniform conductive heat to the lens mold assembly. The rubber disc 20 is l,ler~.ably made of silicone and preferably has a diameter of ap~Jlu~illldt~ly 74 mm and a thickness of about 3 mm. The lens mold assembly preferably is placed on mold 928 so that outside face 906 of a mold member of the assembly rests on top of mold 928. It is preferred that the edge of the lens mold assembly not directly contact the hot plate. The lens mold assembly preferably receives heat through the rubber disc and not through its mold edges.
To achieve good yield rates and reduce the inridence of ~ .llalule release while using the conductive heat method, it may be necessary for the edge of the lens be completely cured and dry before conductive heat is applied. If the lens edge is iu-o .p!i ~ ly cured (i.e., liquid or gel is still present) while conductive heat is applied, there may be a high inci~irnre of ~ lld1~ulc; release of the lens from the heating unit.
In an e---bodi,..ent, the edges of a lens are treated to cure or remove iUCulllpl ~ Iy cured lens forming material (see above description) before cûnductive heat is applied. The mold cavity may be defined by at least gasket 908, first mold member 902, and second mold member 904. Ultraviolet rays are directed toward at least one of the mold members, thereby curing the lens forming material to a lens preferably having front face 916, a 35 back face 915, and edges. Upon the formation of the lens, the gasket may be removed from the mold assembly.
An oxygen barrier may be used to cure any rPm~ining liquid or gel on the lens edge according to any of the methods of the above-detailed embc ' An oxygen barrier treated with photoinitiator is preferably employed. Alternatively, any remaining liquid or gel may be removed manually. Once the edge of the lens is dry, a face of the lens may be conductively heated using any of the methods described herein.

CA 022~1649 1998-10-13 In an ernbo~iimrnt, a lens is tinted after receiving conductive heat postcure tl ~a~ Cut in a mold eavity.
During tinting of the lens, the lens is preferably immersed in a dye solution.

A liquid lens forming co...po~;lion was initially cured in a process and ayy ualuS similar to that speeified in Example I except for post-eure treatment which was con~h-r~r(l as follows:

After the sample was irradiated for 15 minutes, the lens was removed from the FC- 104 chamber and then passed through the above-mentioned UVEXS Model 912 curing chamber (see Figure 10) to receive a dose of about 1500 mJ/cm ~ (+/- 100 mJ) of ultraviolet light per pass. The gasket was then removed from the mold assembly and the edges of the mold were wiped with an absu~ tissue to remove incompletely cured lens forming material ylu~iluale the mold edges. A strip of plastic material i-.~y~- ~.-aled with photoinitiator was 15 wrapped around the edges of the molds that were exposed when the gasket was removed. Next, the mold assembly was passed through the UVEXS curing chamber once to expose the front surface of the mold to a dose of about 1500 mJ/em 2 The mold assembly was then passed through the UVEXS four more times, with the baek surfaee of the mold receiving a dose of about 1 500mJ/cm 2 per pass. A hot plate was operated such that the surface of the hot plate reached a temperature of 340 degrees F (~/- 50 degrees F). A conformable "beanbag"
20 cu.llaill.,, having a covering made of Nomex TM fabric was placed on the hot plate. The container cOIllaillcd glass beads and was turned over such that the portion of the eontainer that had direetly eon~ted the hot plate (i.e., the hottest portion of the eontainer) faced upward and away from the hot plate. The mold assembly was then plaeed onto the heated~ exposed portion of the cu,.l~i~.e. that had been in direet eontact with the hot plate. The eoneave, non-easting face of the mold was plaeed onto the exposed surface of the eontainer which subst~nti~lly 25 cu,,ru....cd to the shape of the face. Heat was conti~rt~ d through the eontainer and the mold member to the lens for 13 minutes. A lens having a Shore D hardness of 84 was formed.

PULSED ULTRAVIOLET LIGHT APPLICATION

A polymerizable lens forming c~,.. pos;l ;on may be plaeed in â mold/gasket assembly and eorltinn li Iy exposed to dyyl uyl ia~ Ievels of ultraviolet light to eure the co-.-po~;lion to an optieal lens. The progress of the euring reaetion may be determined by ~..onilo. ~ g the internal h.l-p. . alul ~ of the co...yu~iliull. The lens forming eu~ os;~ion may be considered to pass through three stages as it is eured: (I) Tn~ rtjon, (2) Gel Formation &
Exotherm, and (3) Extinetion. These stages are illustrated in Fig. 20 for a -.75 -1.00 power lens cured by 35 eontin~ouc application of UV light. Figure 20 shows t~.lly~d~ul~ within the mold cavity as a function of time ~Lu. v' _ a cnntimlouc radiation curing eyele.

CA 022~1649 1998-10-13 W O 97/39880 PCT~US97/06641 The inAIlrtifm stage occurs at the beginning of the curing cycle and is typically cl.a a~ ,d by a sn~ a; Illy steady t~ "alulc (or falling L~ ,lalulc when the curing chamber tc.lll)~,ldIulc is below that of the c~ o~iliv..) of the lens forming co"")v~ilion as it is illaJial~,d with ultraviolet light. During the in~UCtior~
period~ the lens forming co-"po~ilion remains in a liquid state as the photoinitiator breaks down and cou~
5 inhibitor and dissolved oxygen present in the cc,l.-posilion. As the inhibitor content and oxygen content of the culll~,Gailiûn fall. deculll~)oshlg photoinitiator and the cu~uyo ~ on begin to form chains to produce a pourable, "syrup-like" material.

As irradiation co.,~;... s, the "syrup" proceeds to develop into a soft, non-pourable, viscous, gel. A
10 notieeable quantity of heat will begin to be g~n~aled during this soft gel stage. The optical quality of the lens may be affeeted at this point. Should there be any sharp 'I;'CC!~II;-- .;l;f c in the intensity of the activating ullla~riol~t light (for example, a drop of co ~po,;l ;on on the exterior of a mold which focuses light into a portion of the lens forrning co~ o~;~ ;o~ urd~lale the drop), a loeal distortion will tend to be ereated in the gel strueture, likely eausing an ab.,..dlion in the final produet. The lens forming composition will pass through this very soft 15 gel state and through a firm gel state to become a erystalline strueture. When using OMB-91 lens forming c.~ ~;-v~ n a haze tends to form mom-ontP~ily during the transition between the gel and crystalline stages. As the reaetion coT~tin~Pc and more double bonds are conclln~ the rate of reaction and the rate of heat gC.I~,.ahd by the reaetion will slow, whieh may eause the internal l~ alulc of the lens forming cu.llpo~;Lion to pass through a ,..-x i....l.ll at the point where the rate of heat generation exaetly matehes the heat removal eapaeity of the 20 system.

By the time the m~Yiml-m te~ Jc~alUIC has been reaehed and the lens forming culllpo~ilion begins to cool, the lens will typically have aehieved a erystalline form and will tend to erack rather than erumble if it is broken. The rate of eonversion will slow dlalllalically and the lens may begin to cool even though some reaction 25 still may be occurring. Irradiation may still be applied through this extinction phase. Generally, the curing cycle is assumed to be complete when the l~ ,-alUI~; of the lens forming composition falls to a lc.-~pe. aLwc near its t~ ,.alul~ at the beginning of exotherm (i.e., the point where the ~-,.np.,.a~ulc of the cnnnrosition inclcased due to the heat released by the reaction).

The continllouc irradiation method tends to work well for relatively low mass lenses (up to about 2û-25 grams) under the FC-104 curing chamber con~iifiorlc (see, e.g., U.S. Patents 5,364,256 and 5,415,816). As the amount of material being cured increases, IJlUtl~ lls may be ~ ,t~ ~~,d. The total amount of heat 5~,...,._~.ed during the exotherrnic phase is s.,l"l a;~lly l,-u~ iollal to the mass of the lens forming material. During curing of relatively high mass lenses, a greater amount of heat is g alcd per a given time than during curing of lower 35 mass lenses. The total mold/gasket surface area available for heat transfer (e.g., heat removal from the lens forming culll~,o~ilion), however, remains ~ub~ 11y constant. Thus the internal ic.ll~,.alulc of a relatively high mass of lens forrning material may rise to a higher lc~llp~alule more rapidly than typically occurs with a lower mass of lens forming material. For example, the internal IC~ all~c of a low minus cast-to-finish lens typically will not exceed about 100 F, whereas certain thicker semi-finished lens "blanks" may attain tclll~J~,Ialul~,s greater CA 022~1649 1998-10-13 than about 350 F when contin~ ly exposed to radiation. The lens forming material tends to shrink as curing proceeds and the release of excessive heat during curing tends to reduce the adhesion between the mold and the lens forming material. These factors may lead to p~ L problems of ~ alule release and/or cracking during the curing of lens forming material having a relatively high mass.

A cignifirAnt advantage of the present invention is the production of relatively high-mass, semi-finished lens blanks and high power cast-to-finish lenses without the above-merltir~ned problems of pl~,lllalulc release and cracking. Methods of the present invention as described below allow even more control over the process of curing ophtl~lmir lenses with ultraviolet light-initiated polymerization than previous methods. By 10 illl~,.luylhlg or decreasing the activating light at the proper time during the cycle, the rate of heat generation and release can be controlled and the inridPnl~e of premature release can be reduced. An embodiment of the invention relates to a method of controlling the rate of reaction (and therefore the rate of heat generation) of a UV light-curable, lens forming material by applying selected intermittent doses (e.g., pulses) of radiation followed by selected periods of decreased UV light or "darkness". It is to be understood that in the description that follows, 15 "darkness" refers to the absence of activating radiatiom and not necessarily the absence of visible light.

More particularly, an embodi---cnl of the invention relates to: (a) an initial exposure period of the lens forming material to radiation ~e.g., continllouc or pulsed radiation) ~xt~n~ing through the induction period, (b) u~ lg or decreasing the hladialion before the material reaches a first le,llp~,.a~ulc (e.g., the mAYi~nl-nn 20 t~ ,latu~c the CO~ Gsilion could reach if irradiation were cu,~l;..u-d) and allowing the reaction to proceed to a second t~ . alul c lower than the first l~ .alul c, and (c) applying a sufficient number of alternating periods of exposure and decreased UV light or darkness to the lens forming material to complete the cure while controlling the rate of heat generation and/or ,liccirAtic n via manipulation of the timing and duration of the radiation, or the cooling in the curing chamber. Figure 21 shows the t.,.ll~u~ .alu~c within the mold cavity as a function of time for 25 both (a) contim-ouc ultraviolet light exposure and (b) pulsed ultraviolet light exposure.

In the context of this application, a "gel" occurs when the liquid lens forming Co~ OSiliOn is cured to the extent that it becomes s~h~ lly non-pourable, yet is still ,~b~lh~ lly deformable and 5llhstAntiAIly not crystallized.
In the following description, it is to be understood that the term "first period" refers to the length of time of the initial exposure period where radiation (e.g., in pulses) is applied to the lens forming co",l.o~:l ion, preferably to form at least a portion of the colll~osilioll into a gel. "First ultraviolet" rays or light refers to the ~ radiation applied to the lens forming co---l,.. ;l ;OIl during the initial exposure period. "Second ultraviolet" rays or 35 light refers to the radiation that is applied to the lens forming composition (e.g., in pulses) after the Cblll~-O~i~ion has been allowed to cool to the "third t~ alulc" mc.lliu..cd above. "Second period" refers to the duration of time that second ultraviolet rays are directed to the lens forming co,l,~,o~iliv~. "Third period" refers to the duration of decreased UV light or darkness than ensues after UV light has been delivered in the second period.

CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 In an embodiment of the invention, the lens forming material is placed in a mold cavity defined in part between a first mold member and a second mold member. The first mold member and/or second mold member may or may not be contimloucly cooled as the formation of the lens is c.""pl~,t~,d during the second period and/or third period. One method of removing heat from the lens forming material is to continuously direct air at a non-5 casting face of at least one of the mold members. It is preferred that air be directed at both the first and secondmold members. A cooler may be used to cool the ~ atul ci of the air to a l~
lp~,.aLul ~ below ambient ,ld~UI~i, more preferably between about 0 C and about 20 C, and more preferably still between about 3 C
and about 15 C. Air may also be used to cool at least one of the mold members (in any of the manners described previously) during the first period.
In an embodiment of the invention, the first period ends when at least a portion of the lens forming co~ o~;~ ion begins to increase in It~ /."alulc; or form a gel, and the first ultraviolet rays are de~ ase~ or removed (e.g., blocked) such that they cease to contact the first or second mold members. It is preferred that the first period be Sllrr~ ,." to allow the lens forming material to gel in the mold cavity such that there is 5~h.~ ul;_lly 15 no liquid present (except small amounts proximate the edge of the material). The i~lt." u}Jtion of irradiation prior to complete gelation may in some Ch~ C~'~ produce optical distortions. It is preferred that the length of the first period be selected to inhibit the lens forming co",l,osilion from reaching a first l~ ,.dlUI~. The first t~"l~J~"aiulc is preferably the m~Yimnm ~ alulc~ that the lens forming cu"")G~ilion could reach if it was i -alial-,d under the system con~iition~ (e.g., flow rate and l~ alulc: of any cooling air, ~a.~el~ ,lh and 20 intensity of radiation) until the "exothermic potential" (i.e., ability to evolve heat through reaction) of the C~ ion was f~Yh~ct~

According to an en bodiment of the invention, the reactions within the cu""~)G~ilion are allowed to proceed after the first ultraviolet ravs are removed until the composition reaches a second t~lll,uc~alul~. The 25 second tcllllJcldlult: is preferably less than the first Iclllp~,ldlule. The first l~,UI~.,.dtUI~ is preferably never reached by the colll~o~ilion. Thus, preferably the co~ll,i)o~ilion is prevented from achieving the first t~,lllp~ldlul ~ and then cooling to the second tl,lll,u~,l d~ul~;. The c~....l .o~i~ ion preferably is allowed to cool from the second l~lllp~,lalul~ to the third l.,lll~ d~ul~. This cooling may occur "inactively" by allowing heat to transfer to the ambient surroun-lings, or at least one of the mold members may be cooled by any of the methods described above.
In an embodiment of the invention, the curing of the lens forming material is completed by directing second ultraviolet rays (e.g., in pulses) toward at least one of the mold members. The second UV rays may be directed toward the mold member(s) for a second period that may be determined according to the rate of reaction of the lens forming composition. The change in t~ ]C. dtUI ~i of the composition or a portion of the mold cavity, 35 or the air in or exiting the chamber is an indicator of the rate of reaction, and the second period may be determined accordingly. The second period may be varied such that sllhseqllPnt pulses have a longer or shorter duration than previous pulses. The time between pulses (i.e., the third period) may also be varied as a function of the te~ ldlb.t: and/or reaction rate of the composition. To achieve a light pulse, (a) the power to a light source may be turned on and then off, (b) a device may be used to alternately transmit and then block the passage of light CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 to the lens forming co...l)o~i~iol). or (c) the light source and/or mold assembly may be moved to inhibit ultraviolet light from c g the lens forming material. The second and/or third periods are preferably controlled to allow rapid formation of a lens while reducing the inr~ ?nce of (a) premature release of the lens from the first andlor second mold member and/or (b~ cracking of the lens.
In an embodiment, the second period is preferably controlled to inhibit the tC~Ily~,~ alul ~ of the cu...l~o~ilion from eYree~1inE the second 1~ aLul~. The t~,lnlJ~ .alul~ of the lens forming composition may continue to increase after radiation is removed from the first and/or second mold members due to the exothermic nature of reactions occurring within the composition. The second period may be sufficiently brief such that the 10 pulse of second ultraviolet rays is removed while the t~ .lly~,.aLul~ of the co,..yosi~ion is below the second Ic.llp~ ~ alu~ e~ and the t~ .llp. . dlul ~ of the cu...poailion increases during the third period to become s~ ~l . U i~ y equal to the second t.~lllp. ~alul~ at the point that the tCIlly~.ldlUl~ of the composition begins to decrease.

In an embodiment, the third period extends until the Itlllp~ la~ul~ of the cullll,ûsilion becomes 15 suks~-ti~llyequaltothethirdt~lllyclalul~ Oncethetelllp~lalul~ofthecu---yo~i~ionde.-~dscstothethird l~l,.p~ldlllre, a pulse of second ultraviolet rays may be delivered to the cu~po~ In an embodil..c..l, the second period remains constant, and the third period is controlled to maintain the l~llly~lalul~ of the c.,...~,fss:~;on below the second temperature. The third period may be used to lower the l-,.lllJl,.a~ulc: of the co..lpoai~ion to a tc.l.y~.alul~ that is expected to cause the composition to reach but not exceed the second L~.lly~aLul~; after a pulse 20 is delivered to the composition.

In an embo.;li"u,..~, shutter system 950 (shown in Fig. 7) is used to control the application of first and/or second ultraviolet rays to the lens forming material. Shutter system 950 preferably includes air-actuated shutter plates 954 that may be inserted into the curing chamber to prevent ultraviolet light from reaching the lens 25 forming material. Shutter system 950 may include y.o~.a.. able logic controller 952, which may actuate air cylinder 956 to cause shutter plates 954 to be inserted or extracted from the curing chamber. Programmable logic controller 952 preferably allows the insertion and extraction of shutter plates 954 at specified time intervals.
P~uy,~ ...,.able logic controller 952 may receive signals from thermocouple(s) located inside chamber, proximate at least a portion the mold cavity, or located to sense the h,nly~lalul~ of air in or exiting the chamber, allowing the 30 time intervals in which the shutters are inserted and/or extracted to be adjusted as a function of a l~lllyc~dlul~
within the curing chamber. The thc.---ocuul,le may be located at I~UUII.,.OUS positions IJlu,.i..lal~ the mold cavity and/or casting chamber.

The wavelength and intensity of the second ultraviolet rays are preferably svl,.~ lly equal to those 35 of the first ultraviolet rays. It may be desirable to vary the intensity and'or wavelength of the radiation (e.g, first or second ultraviolet rays). The particular wavelength and intensity of the radiation employed may vary among embodiments according to such factors as the identity of the composition and curing cycle variables.

CA 022~1649 1998-10-13 W O 97139880 PCTrUS97/06641 Nu~ uua curing cycies may be designed and employed. The design of an optimal cycle should include consideration of a number of interacting variables. Significant in~l~penr~nt variables include: I ) the mass of the sample of lens forming material. 2) the intensity of the light applied to the material, 3) the physical cllalac~ liCs of the lens forming material, and 4) the cooling efficiency of the system. Significant curing cycle S (d~ ) variables include: 1) the optimum initial exposure time for indllç~i~n and gelling, 2) the total cycle time, 3) the tirne period between pulses. 4) the duration of the pulses, and S) the total exposure time.

Most ofthe e,~.,"..,.,l~ involving methods ofthe present invention were con~cted using below described OMB-91 monomer and the above-mentioned FC-104 curing chamber sel at an operating t~ alul~i of 10 55 degrees F, although tests have been p.,. ru, I"cd using other lens forrning materials and curing chamber l."llp~ld~UI~. The OMB-91 formulation and properties are listed below.

OMB-91 FORMULATION:
INGREDIENT WEIGHT PERCENT
SartomerSR351 (Trimethylolpropane Triacrylate) 20.0 +/- 1.0 Sartomer SR 268 (Tetraethylene Glycol Diacrylate) 21.0 +/- 1.0 Sartomer SR 306 (Tripropylene Glycol Diacrylate) 32.0 +/- 1.0 Sartomer SR 239 (1,6 Hf Xi' ~i;ol Di.".,ll,ac,ylate) 10.0 +/- 1.0 20 (Bisphenol A Bis(Allyl Carbonate)) 17.0 +/- 1.0 Irgacure 184 (I-Hydroxycyclohexyl Phenyl Keytone) 0.017 +/- 0.0002 Methyl Benzoyl Formate 0.068 +/- 0.0007 MethylEsterofHy-l,u., ~("MeHQ") 35ppm +/ 10ppm Thermoplast Blue P (9,10 - A~ .c~ione 0.35 ppm +/- 0.1 ppm 1-hydroxy-~-((4-methyl phenyl) Amino) , CA 022~1649 1998-10-13 W O97/39880 PCT~US97/06641 MEASUREMENTS/PROPERTIES:
PROPERTY PROPOSED SPECI~ICATION

Appearance Clear Liquid Color (APHA) 50 m l~imnm (Test Tube Test) Match Standard Acidity (ppm as Acrylic Acid) 100 m~Yin.. rn 10 Refractive Index 1.4725 +/- 0.002 Density 1.08 +/- 0.005 gm/cc. at 23 degrees C.
Viscosity ~ 22.5 Degrees C. 27.0 +/- 2 centipoise Solvent Weight (wt %) 0.1 Maximum Water (wt %) 0.1 Maximum 15 MeHQ (from HPLC) 35 ppm +/- 10 ppm It is recogni7~d that methods and systems of the present invention could be applied to a large variety of radiation-curable, lens forming materials in addition to those mentioned herein. It should be understood that 20 adjucttnentc to curing cycie variables (particularly the initial exposure time) may be required even among lens forming cu~")osilions of the same type due to variations in inhibitor levels among batches of the lens forming cul~ os;l;onc In addition. changes in the heat removal capacity ofthe system may require adjustments to the curing cycle variables (e.g. duration of the cooling periods bet~veen radiation pulses). Changes in the cooling capacity of the system and/or changes in col..; oc;~ions of the lens forming material may require adjustrnents to 25 curing cycle variables as well.

Significant variables imr~cting the design of a pulsed curing cycle include (a) the mass of the material to be cured and (b) the intensity of the light applied to the material. A significant aspect of methods of the present invention is the initial exposure period. If a sample is initially overdosed with radiation, the reaction may 30 progress too far and increase the likelihood of premature release and/or cracking. If a sample is underdosed initially in a fixed (i.e., preset) curing cycle~ suhs~quent exposures may cause too great a temperature rise later in the cycle, tending to cause premature release and/or cracking. Additionally, if the light intensity varies more than about +/- 10% in a cycle that has been designed for a fixed light intensity level and/or fixed mass of lens forming material, premature release and/or cracking may result.
An embodiment of the present invention involves a curing cycle having two l)locesses. A first process relates to forming a dry gel by continllol~cly irradiating a lens forming co...~o~iLion for a relatively long period.
The material is then cooled down to a lower l~,...p.,.~lLul~ under darkness. A second process relates to controllably CA 022~1649 1998-10-13 ~liscl.a. ~;ing the remaining exothermic potential of the material by alternately exposing the material to relatively short periods of irradiation and longer periods of decreased irradiation (e.g., dark cooling).

The behavior of the lens forming material during the second process will depend upon ehe degree of 5 reaction of the lens forming material that has occurred during the first process. For a fixed curing cycle, it is pl~l~,able that the extent of reaction occurring in the first process concict~ntly fall within a specified range. If the progress of reaction is not controlled well, the incidence of cracking and/or ~ lldLUI~ release may rise. For a curing cycle involving a co,ll?osilion having a constant level of inhibitor and initiator, the intensity of the radiation employed is the most likely source of variability in the ievel of cure attained in the first process.
10 Generally, a fluctl~ ~tion of +/- 5% in the intensity tends to cause observable differences in the cure level achieved in the first process. Light intensity variations of +/- 1 0~/O may significantly reduce yield rates.

The effect of various light int~nsities on the material being cured depends upon whether the intensity is higher or lower than a preferred intensity for which the curing cycle was (lesign~ Fig. 23 shows t~ ,.alule 15 profiles for three embodiments in which different light levels were employed. If the light intensity to which the material is exposed is higher than the preferred intensity, the overdosage may cause the reaction to proceed too far. In such a case, excessive heat may be gc,l.,..~t-,d, increasing the possibility of cracking and/or l,re.lla~
release during the first process of the curing cycle. If premature release or cracking of the overdosed material does not occur in the first process, then cl~hsequf~nt pulses ~iminict~red during the second process may create 20 very little additional reaction.

If the light intensity is lower than the preferred intensity and the lens forming material is ullde.dosed, other problems may arise. The material may not be driven ~o a ~.lrrl-,;c.-t level of cure in the first process. Pulses applied during the second process may then cause relatively high amounts of reaction to occur, and the heat 25 generated by reaction may be much greater than the heat removal capacity of the system. Thus the t~ .,.dul~i of the lens forming material may tend to excessively increase. Premature release may result. Otherwise, undercured lenses that continue ~,~,u.,. dlhlg heat after the end of the cycle may be produced.

The optimal initial radiation dose to apply to the lens forming material may depend primarily upon its 30 mass. The initial dose is also a function of the light intensity and exposure time. A method for rl~cigning a curing cycle for a given mold/gaskeVmonomer con.b;,.d~io" may involve selecting a fixed light intensity.

Methods of the present invention may involve a wide range of light int~n.citicc Using a relatively low intensity may allow for the length of each cooling step to be de.,l~ased such that shorter and more controllable 35 pulses are applied. Where a fluorescent lamp is employed, the use of a lower intensity may allow the use of lower power settings, thereby reducing the load on the lamp cooling system and ~xten~ing the life of the lamp. A
disadvantage of using a relatively low light intensity is that the initial exposure period tends to be SUIII~Ld~
longer. Relatively high intensity levels tend to provide shorter initial exposure times while placing more demand upon the lamp drivers and/or lamp cooling system, either of which tends to reduce the life of the lamp.

CA 022~1649 1998-10-13 W O 97139880 PCTrUS97/06641 In an embodiment, General Electric FIST8BL lamps powered by Mercron HR0696-4 drivers may be used in conju~lrtiorl with an FC 104 curing chamber having one piece of double-frosted diffusing glass and one piece of clear P0-4 acrylic plate. The light intensity settings may be 760 microwatts/cm for the top lamps and 950 microwatts/cm for the bottom lamps.

Once a light intensity is selected, the initial exposure time may be determined. A convenient method of monitoring the reaction during the cycle involves fashioning a fine gage thermocouple, pocitinning it inside the mold cavity, and conne~,~i.lg it to an ap~,u~,liale data acquisition system. The preferred thermocouple is Type J, 0.005 inch diameter, Teflon-insulated wire available from Omega Engineering. The insulation is stripped back about 30 to 50 mm and each wire is passed through the gasket wall via a fine bore hypodermic needle. The needle is then removed and the two wires are t~visted together to form a thermocouple junction inside the inner circumference of the gasket. The other ends of the leads are attached to a miniature connector which can be plugged into a permanent thermocouple extension cord leading to the data acquisition unit after the mold set is 1 5 filled.

The data :lfqllicition unit may be a Hydra 2625A Data Logger made by John Fluke Mfg. Company. It is co~ e~ d to an IBM compatible personal u~ ,uL~ running Hydra Data Logger software. The computer is configured to display a trend plot as well as numeric ~ ,,alulc readings on a monitor. The scan interval may 20 be set to any convenient time period and a period of five or ten seconds usually provides good resolution.

The position of the thermocouple junction in the mold cavity may affect its reading and behavior through the cycle. When the junction is located between the front and back molds, relatively high L~,.llp.,.d~l.leS
may be observed culll~Jal~,d to the temperatures at or near the mold face. The distance from the edge of the cavity to the junction may affect both absolute temperature readings as well as the shape of the curing cycles' le.~ aLulc plot. The edges of the lens forming material may begin to increase in Ic.ll~J~,.alulc slightly later than other portions of the material. Later in the cycle, the lens forming material at the center may be somewhat ahead of the material at the edge and will tend to respond little to the radiation pulses, whereas the material near the edge may tend to exhibit significant activity. When performing CA~JCI ;IllC.ll:~ to develop curing cycles, it is 30 preferred to insert two probes into the mold cavity, one near the center and one near the edge. The center probe should be relied upon early in the cycle and the edge probe should guide the later stages of the cycle.

Differing rates of reaction among various regions of the lens forming material may be achieved by applying a ~lirrc~ Lidl light distribution across the mold face(s). Tests have been performed where "minus type"
light distributions have caused the edge of the lens forming material to begin reacting before the center of the material. The potential advantages of using light di ,LIibuLillg filters to cure high mass semi-finished lenses may be offset by nonuniformity of total light tr~rlcmicciorl that tends to occur across large numbers of filters. The UV

CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97106641 light transmission of the PO-4 acrylic plates (Cyro Industries; Plano~ Texas) used over the apertures in the FC-104 curing chamber tends to be considerably more col.c;~t~ ,n than that of silk-screened filter plates.

After the selection and/or configuration of ~a) the radiation intensity, (b) the radiation-curable, lens S forming materiaL (c) the mold/gasket set, and (d) the data acquicition system, the optimum initial exposure period may be determined. It is useful to expose a sample of lens forming material to continuous radiation to obtain a alul~ profile. This will provide an irlrntifi~hle range of elapsed time within which the optimal initial exposure time will fall. Two points of interest are the time where the ~ ,..e.atu,~ rise in the sample is first detected ("T initial" or "Ti"), and the time where the m~-~imum t~,.ll~).,.aluli of the sample is reached ("Tmax").
10 Also of interest is the actual maximum l.,.lllJ~.allu~, an indication of the "heat potential" of the sample under the system conditions (e.g., in the presence of cooling).

As a general rule, the I~ uc.aIul~ of high mass lenses (i.e., lenses greater than about 70 grams) should remain under about 200 F and preferably between about 150 F and about 180 F. Higher temperatures are 15 typically associated with reduced lens yield rates due to cracking and/or ~n~llaLule release. Generally, the lower mass lenses (i.e., lenses no greater than about 45 grams) should be kept under about 150 F and preferably between about 110 F and about 140 F.

The first period may be selected according to the mass of the lens forming material. In an embodiment, the lens forming material has a mass of between about 45 grams and about 70 grams and the selected second t~lllp~,~aIule is a temperature between about 150 F and about 200 F. According to another e~nborliment, the lens forming material has a mass no greater than about 45 grams and a second I.,.ll,~.c.alul~ less than about 150 F. In yet another embodiment of the invention, the lens forrning material has a mass of at least about 70 grams~ and a second ~c.llp.,.aIul~ between about 170 F and about 190 F.
An e,.y~,.;.l.cllt may be p~ ll--cd in which the radiation is removed from the mold members slightly before one-half of the time between T initial and Tmax. The initial exposure time may be interatively reduced or i--~,-~dscd according to the results of the above t;~y~.~ i..n,.-~ in ~ sc~ ~.1 expc. hllc..l~ to provide a Tmax in the preferred range. This p.oce.lu,~ may allow the determination of the optimal initial exposure time for any given mold/gasket set and light intensity.

A qualitative summary of relationships among system variables related to the above-described methods is shown in Fig. 22.

After the initial exposure period, a series of irradiation pulse/cooling steps may be performed to controllably .li~chal~c the remaining exothermic potential of the ma~erial and thus complete the cure. There are at least t~vo dp~)l oacl.~,s to accomplish this second process. The first involves applying a large number of very short pulses and short cooling periods. The second approach involves applying a fewer number of longer pluses CA 022~1649 1998-10-13 W 097139880 PCTrUS97/06641 with co"~ .u"dingly longer cooling periods. Either of these two methods may produce a good product and many acceptable cycles may exist between these extremes.

A significant aspect of the invention relates to using pulsed application of light to produce a large - 5 range (e.g., from -6 to +4 diopter) of lenses without requiring ~er~igclaL~d cooling fluid (e.g., cooled air). With proper light application. air at ambient may be used as a cooling fluid, thus cignifir~ntly reducing system costs.

Some established cycles are detailed in the table below for three sPnnifiniched mold gasket sets: a 6.00D base curve. a 4.50D base curve, and a 3.00D base curve. These cycles have been performed using an FC-10 104 curing chamber in which cooling air at a temperature of about 56 degrees F was directed at the front and back surfaces of a mold assembly. Frosted diffusing window glass was positioned between the samples and the lamps, with a layer of PO-4 acrylic material dpp~oxil~,ately 1 inch below the glass. A top light intensity was adjusted to 760 microwatts/cm~ and a bottom light intensity was adjusted to 950 microwatts/cm~, as IllCdSUl ed at about the plane of the sample. A Spectroline meter DM365N and standard detector stage were used. An in-mold coating as 15 described in U.S. application serial no. 07/931,946 was used to coat both the front and back molds.

CA 022~1649 1998-10-13 W 097/39880 PCT~US97/06641 BASE CURVE
MoldSets 6.00 4.50 3.00 Front Mold 5.95 4.45 2.93 Back Mold 6.05 6.80 7.80 Gasket -5.00 13 mm 16 mm Resulting Sennifiniched Blank Diameter 74 mm 76 mm 76mm CenterThickness 9.0mm 7.8 mm 7.3 mm Edge Thickness 9.0 mm 11.0 mm 15.0 mm Mass 46 grams 48 grams 57 grams Curing Cycle Variables Total Cycle Time 25:00 25:00 35:00 Initial Exposure 4:40 4:40 4:35 Number of Pulses 4 4 4 Timing (in seconds) and Duration of Pulses (~,) Elapsed Time From Onset of Initial Exposure Pulse 1 15(~10:00 15~10:00 15~13:00 Pulse 2 15~15:00 15~15:00 15~21:00 Pulse 3 30~19:00 30~19:00 20~27:00 Pulse 4 30~22:00 30~22:00 30~32:00 Figures 24,25, and 26 each show lL~ ,.a~ul c profiles of the above-detailed cycles for a case where the 5 ultraviolet light exposure is continllouc and a case where the ultraviolet light delivery is pulsed. In Figures 23-26, "lo" denotes the initial intensity of the ultraviolet rays used in a curing cycle. The phrase "lo=760/950" means that the light intensity was adjusted to initial settings of 760 microwatts/cm for the top lamps and 950 --i-,~v~al~/cm for the bottom lamps. The "interior temperature" of Figures 23-26 refers to a L~ alulc of the lens forming material as measured by a thermocouple located within the mold cavity.

The following general rules for the design of pulse/cooling cycles may be employed to allow rapid curing of a lens while inhibiting premature release and/or cracking of the lens. The duration of the pulses preferably does not result in a tc~ alul~i that exceeds the m~imllm ~ lp~dlUI~; attained in the initial exposure period. The length of the cooling period may be determined by the length of time necessary for the internal CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 alu~e of the lens forming material to return to near the ~ d~u~ ~ it had imme~ tply before it received a pulse. Following these general rules during routine experimentation may permit proper curing cycles to be established for a broad range of lens forming materials, light intensity levels, and cooling conditions.

S Preferably light output is measured and controlled by varying the amount of power applied to the lights in response to changes in light output. Specifically, a preferred embodiment of the invention includes a light - sensor mounted near the lights. This light sensor measures the amount of light, and then a controller increases the power supplied to maintain the first ultraviolet rays as the intensity of the first ultraviolet rays decreases during use, and vice versa. Specifically, the power is varied by varying the electric frequency supplied to the lights.
A filter is preferably applied to the light sensor so that light waves other than ultraviolet light impinge less, or not at all, on the light sensor. In one Pmbo~iment, a piece of 365N Glass made by Hoya Optics (Fremont, California) was applied to a light sensor to filter out visible rays.

One "lamp driver" or light controller was a Mercron Model FX0696-4 and Model FX06120-6 (Mercron, Inc.. Dallas, Texas, U.S.A.). These light controllers may be described in U.S. patents 4,717,863 and 4,937,470.

Figure 13 s~hem~tin~lly depicts the light control system described above. The lights 40 in a~J~Jaldl~l5 20 10 apply light towards the lens holder 70. A light sensor 700 is located adjacent the lights 40. F'. ~1~. ably the light sensor 700 is a photoresistor light sensor (photodiodes or other light sensors may also be usable in this application). The light sensor 700 with a filter 750 is connected to lamp driver 702 via wires 704. Lamp driver 702 sends a current through the light sensor 700 and receives a return signal from the light sensor 700. The return signal is CO~lp~ ~,d against an adjustable set point, and then the electrical frequency sent to the ultraviolet lights 40 25 via wires 706 is varied /lepPnrling on the differences between the set point and the signal received from the light sensor 700. Preferably the light output is m lint~inPd within about +/- 1.0 percent.

In an emho~ "1 of the invention, a medium pressure mercury vapor lamp is used to cure the lens forming material and the lens coating. This lamp and many conventional light sources used for ultraviolet light 30 curing may not be repeatedly turned on and off since a several minute warm-up period is generally required prior to operation. Mercury vapor light sources may be idled at a lower power setting between exposure periods (i.e., second periods), however, the light source will still generate significant heat and consume electricity while at the lower power setting.

In an embodiment, a flash lamp emits ultraviolet light pulses to cure the lens forming material. It is believed that a flash lamp would provide a smaller, cooler, less expensive, and more reliable light source than other sources. The power supply for a flash lamp tends to draw relatively minimal current while charging its capacitor bank. The flash lamp d;5~1~a~ 1 the stored energy on a microsecond scale to produce very high peak intencjtjeS from the flash tube itself. Thus flash lamps tend to require less power for operation and generate less CA 022~1649 1998-10-13 heat than other light sources used for ultraviolet light curing. A flash lamp may also be used to cure a lens coating.

In an embodiment, the flash lamp used to direct ultraviolet rays toward at least one of the mold 5 members is a xenon light source. The lens coating may also be cured using a xenon light source. Referring to Fig. 29, xenon light source 980 preferably contains photostrobe 992 having a tube 996 and electrodes to allow the transmission of ultraviolet rays. The tube may include borosilicate glass or quartz. A quartz tube will generally withstand about 3 to 10 times more power than a hard glass tube. The tube may be in the shape of a ring, U, helix, or it may be linear. The tube may include capacitive trigger electrode 995. The capacitive trigger electrode 10 may include a wire. silver strip, or conductive coating located on the exterior of tube 996. The xenon light source is preferably adapted to deliver pulses of light for a duration of less than about I second, more preferably between about 1/10 of a second and about 111000 of a second, and more IJlcfe,ably still between about 1/400 of a second and 1/600 of a second. The xenon source may be adapted to deliver light pulses about every 4 seconds or less.
The relatively high intensity of the xenon lamp and short pulse duration may allow rapid curing of the lens 15 forming CO...~osilion without imparting significant radiative heat to the ~;olnpoailion.

In an Pmhodim,~nt controller 990 (shown in Fig. 29) controls the intensity and duration of ultraviolet light pulses delivered from ultraviolet light source 980 and the time interval between pulses. Ultraviolet light source 980 may include capacitor 994, which stores the energy required to deliver the pulses of ultraviolet light.
20 Capacitor 994 may be adapted to allow pulses of ultraviolet light to be delivered as frequently as desired.
Tc~ aLu~c monitor 997 mav be located at a number of positions within mold chamber 984. The ~ UIC
monitor may measure the ~ p~,,aLulc within the chamber and/or the h,.ll~J- ,alulc of air exiting the chamber. The system may be adapted to send a signal to cooler 988 and/or distributor 986 (shown in Fig.27) to vary the amount and/or t~,...p~. d~UI c of the cooling air. The t~,mp~,.alul c monitor may also determine the temperature at any of a 25 number of locations proximate ~he mold cavity and send a signal to controller 990 to vary the pulse duration, pulse intensity, or time between pulses as a function of a l~.lly~,.alulc within mold chamber 984.

In an embodiment. Iight sensor 999 is used to determine the intensity of ultraviolet light em?~n~ting from source 980. The light sensor is preferably adapted to send a signal to controller 990, which is preferably 30 adapted to maintain the intensity of the ultraviolet light at a selected level. Filter 998 may be positioned between ultraviolet light source 980 and light sensor 999 and is preferably adapted to inhibit visible rays from co~ .cLillg light sensor 999, while allowing ultraviolet rays to contact the sensor. The filter may include 365 N glass or any other material adapted to filter visible rays and transmit ultraviolet rays.

In an embo~iims~nt a cooling di~l- il~ulo~ is used to direct air toward the non-casting face of at least one ofthemoldmemberstocoolthelensformingcu...po,:~;on Theairmaybecooledtoat~,...l,.,lalu.~iofbelow ambient LCIlll~la~ulc prior to being directed toward at least one of the mold members to cool the composition.

CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 In an embodiment, air at ambient ~ u,c; may be used to cool the lens torming composition.
Since the xenon flash generally has a duration of much less than about one second, considerably less radiative heat tends to be llan~l;ll~ d to the lens forming composition compared to curing methods emploving other ultraviolet sources. Thus~ the reduced heat imparted to the lens forming co.-.posilion may allow for air at ambient S 1~ e.alu.~ to remove sufficient heat of exotherm to 5~ lly inhibit premature release and or cracking of the lens.

In an embodiment, the xenon source is used to direct first ultraviolet rays toward the first and second mold members to the point that a Iclll~lalule increase is measured and/or the lens forming composition begins to 10 or forrns a gel. It is preferred that the gel is formed with less than 15 pulses of radiation, and more preferably with less than about S pulses. It is preferred that the gel is formed before the total time to which the co...po~ilion has been exposed to the pulses exceeds about 1/10 or 1/100 of a second.

In an embodiment. a reflecting device is employed in conjunction with the xenon light source. The 15 ~ellc~,li,lg device is positioned behind the flash source and preferably allows an even distribution of ultraviolet rays from the center of the composition to the edge of the co,lll)o~ilion.

In an embodiment, a xenon light flash lamp is used to apply a plurality of ultraviolet iight pulses to the lens forming coll,i)o~ilion to cure it to an eyeglass lens in a time period of less than 30 minutes. or more 20 preferably, less than 20 or 15 minutes.

The use of a xenon light source also may allow the formation lenses over â wider range of diopters.
Higher power lenses exhibit greatest thinnest to thickest region ratios, meaning that more shrinkage-induced stress is created. causing greater mold flexure and thus increased tendency for premature release. Higher power 25 lenses also possess thicker regions. Portions of lens forming material within these thicker regions may receive less light than regions closer to the mold surfaces. Continuous irradiation lens forming techniques typically require the use of relatively low light int- ncitieS to control the heat generated during curing. The relatively low light int~nr~ s used tends to result in a long, slow gelation period. Optical distortions tend to be created when one portion of the lens is cured at a different rate than another portion. Methods chala.,~ d by non-uniform 30 curing are typically poorly suited for the production of relatively high power lenses, since the deeper regions (e.g." regions within a thick portion of a lens) tend to gel at a slower rate than regions closer to the mold surfaces.

The relatively high intensity attainable with the xenon source may allow deeper penetration into, and/or saturation of, the lens forming material, thereby allowing uniform curing of thicker lenses than in 35 conventional radiation-initiated curing. More uniform gelation tends to occur where the lens forming material is dosed with a high intensity pulse of ultraviolet light and then subjected to decreased UV light or darkness as the reaction proceeds without activating radiation. Lenses having a diopter of between about +5.0 and about -6.0 and greater may be cured. It is believed that light distribution across the sample is less critical when curing and especially when gelation is induced with relatively high intensity light. The lens forming material may be capable CA 022~1649 1998-10-13 OI aDsorDmg an amounl o~ energy per llme tnat IS ~elow tna~ aenverea aurmg a relaIlvely nlgn m~enslty pulse.
The lens forming material may be "ovt:l~a~ulaled" with respect to the light delivered via a high intensity flash source. In an embodiment the xenon source is used to cure a lens having a diopter between about -4.0 and about -6Ø In an embodiment. the xenon source is used to cure a lens having a diopter between about +2.0 and about 5 +4Ø

In an embo.li",c.,l more than one xenon light source is used Simllit~eoucly to apply ultraviolet pulses to the lens forming co,..p~ Such an embodiment is shown in Fig. 28. Xenon light sources 980a and 980b may be positioned around mold chamber 985 so that pulses may be directed toward the front face of a lens and 10 the back face of a lens ~ lly simlllt~neoucly~ Mold chamber 985 is preferably adapted to hold a mold in a vertical position such that pulses from xenon source 980a may be applied to the face of a first mold member while pulses from source 980b may be applied to the face of a second mold member. In an embodiment xenon source 980b applies ultraviolet light pulses to a back surface of a lens more frequently than xenon source 980a applies ultraviolet light pulses to a front surface of a lens. Xenon sources 980a and 980b may be configured such 15 that one source applies light to mold chamber 984 from a position above the chamber while the other xenon source applies light to the mold chamber from a position below the chamber.

In an embodiment a xenon light source and a relatively low intensity (e.g., llUol~ sc- nl) light source are used to 5in~ult ~neously apply ultraviolet light to a mold chamber. As illustrated in Fig. 27 xenon source 980 20 may apply ultraviolet light to one side of mold chamber 984 while low intensity fluorescent source 982 applies ultraviolet light to another side of the mold chamber. ~luorescent source 982 may include a compact fluorescent "light bucket" or a diffused fluorescent lamp. The lluure~ct.-l light source may deliver continuous or lly pulsed ultraviolet rays as the xenon source delivers ultraviolet pulses. The fluorescent source may deliver continuous ultraviolet rays having a relatively low intensity of less than about 0. I watts/cm 2 Methods of the present invention allow curing of high-mass semi-finished lens blanks from the same material used to cure cast-to-finish lenses. Both are co"side,~ d to be "eyeglass lenses" for the purposes of this patent. These methods may also be used to cure a variety of other lens forming materials. Methods of the present invention have been successfully used to make cast-to-finish lenses in addition to semi-finished lenses.
PULSE METHOD EXAMPLE 1: USE OF A MEDIUM PRESSURE VAPOR LAMP
An eyeglass lens was successfully cured with ultraviolet light utilizing a medium pressure mercury vapor lamp as a source of activating radiation (i.e., the UVEXS Model 912 previously desc. il,ed herein). The curing chamber included a six inch medium pressure vapor lamp operating at a power level of a~ illlal~ly 250 35 watts per inch and a defocused dichroic reflector that is highly UV reflective. A high percentage of infrared radiation was passed through the body of the reflector so that it would not be directed toward the material to be cured. The curing chamber further included a conveyer n~rh ~liclll for transporting the sample underneath the lamp. With this curing chamber the transport mechanism was set up so that a carriage would move the sample from the front of the chamber to the rear such that the sample would move completely through an irradiation CA 022~1649 1998-10-13 zone under the lamp. The sample would then be IlallSIJUI L~d through the zone again to the tront ot the chamber.
In this manner the sample was provided with two distinct e,.~.o~u--,s per cycle. One pass, as defined hc.e;..arl.,l, consists of two of these distinct exposures. One pass provided a dosage of approximately 275 milliJoules measured at the plane of the sample using an International Light IL 1400 radiometer equipped with a XRL 340 B
5 detector.

- A lens cavity was crealed using the same molds lens forming cu.. -?o~ilion. and gasket of Pulsed Method Example 2 below. The reaction cell cont~ining the lens forming material was placed on a supporting stage such that the plane of the edges of the convex mold were at a distance of approximately 75 mm from the plane of the 10 lamp. The lens cavity was then exposed to a series of UV doses Con~i~tinp of two passes directed to the back surface of the mold followed immerli~nly by one pass directed to the front surface of the mold. Subseq~Pnt to these first e,.~,u~ , the reaction cell was allowed to cool for 5 minutes in the absence of any activating radiation in an FC-104 chamber as described in Pulsed Method Example I at an air temperature of 74.6 degrees F
and at an air flow rate of approximately 15 to 25 scf per minute to the back surface and 15 to 25 scf to the front 15 surface of the cell. The lens cavity was then dosed with one pass to the front mold surface and returned to the cooling chamber for 6 minutes. Then the back surface was exposed in one pass and then was cooled for 2 minutes. Next, the front surface was exposed in two passes and then cooled for 3.5 minutes. The front surface and the back surface were then each exposed to two passes, and the gasket was removed to expose the edges of the lens. A strip of polyethylene film i..ly.~,g,.aled with photoinitiator was then wrapped around the edge of the 20 lens and the front and back surfaces were exposed to another 3 passes each. The back surface of the cell was then placed on the conductive thermal in-mold postcure device using "bean-bag" container filled with glass beads on a hot plate at about 340 F described previously (see conductive heating example I ) for a time period of 13 minutes, after which the glass molds were removed from the finished lens. The finished lens exhibited a distance focusing power of -6.09 diopters, had excellent optics, was aberration-free, was 74 mm in diameter, and had a 25 center thickness of 1.6 mm. During the cooling steps, a small surface probe thermistor was positioned against the outside of the gasket wall to monitor the reaction. The results are summarized below.

CA 022~1649 1998- 10- 13 UV Dose Approx. Elapsed Time Gasket Wall Temperature After UV Dose (min) (o F) 2 passes to back surface and I pass to 0 Not recorded front surface 80.5 2 79.7 3 79.0 4 77.1 76.2 l pass to front surface 0 Not recorded 83.4 2 86.5 3 84.6 4 Not recorded 81.4 6 79.5 I pass to back surface 0 Not recorded 79.3 2 79.0 2 passes to front surface 0 Not recorded 78.4 2 77.8 3 77.0 3.5 76.7 5 PULSE METHOD EXAMPLE 2: USE OF A SINGLE XENON FLASH LAMP

An eyeglass lens was successfully cured with ultraviolet light utilizing a xenon flash lamp as a source of activating radiation. The flash lamp used was an Ultra 1800 White Lightning photographic strobe, co.,l-llc.-,ially available from Paul C. Buff Inco- yulal~d of Nashville, Tennessee. This lamp was modified by replacing the 10 standard borosilicate flash tubes with quartz flash tubes. A quartz flash tube is preferred because some of the ultraviolet light generated by the arc inside the tube tends to be absorbed by borosilicate glass. The strobe possessed two semicircular flash tubes that trigger simultaneously and are positioned to forrn a ring a~JIuAillldl~ly 73 millimet-ors in diameter. The hole in the reflector behind the lamps, which normally contains a ~lelinp; lamp for photographic purposes, was covered with a flat piece of highly-polished ultraviolet reflective 15 material, which is cu,,~ C,. ;ally available under the trade name of Alzac from Ultra Violet Process Supply of Chicago, Illinois. The power selector switch was set to full power. The ultraviolet energy generated from one flash was measured using an International Light IL 1700 Research Radiometer available from l--l~..,a~iu"al Light, Incorporated of Newburyport. I\l~cQ~rhllcettc The detector head was an International Light XRL 340 B, which is sensitive to radiation in the 326 nm to 401 nm region. The window of the detector head was positioned CA 022~1649 1998-10-13 W 097/39880 PCTrUS97106641 a~ uAi--.alely 35 mm from the plane of the flash tubes and was approximately cen~ered within the ring formed by the tubes. The results showed the power of one flash to be about 940 microwatts.

A mold cavity was created by placing two round 80 mm diameter crown glass molds into a silicone 5 rubber ring or gasket, which possessed a raised lip around its inner circumference. The edges of the glass molds rested upon the raised lip to forrn a sealed cavity in the shape of the lens to be created. The inner circumference - of the raised lip co.. ~,;",o,lded to the edge of the finished lens. The concave surface of the first mold c~ ,ol3ded to the front surface of the finished lens and the convex surface of the second mold corresponded to the back surface of the finished lens. The height of the raised lip of the rubber ring into which the two glass 10 molds are inserted controls the spacing between the two glass molds, thereby controlling the thickness of the finished lens. By selecting proper gaskets and first and second molds that possess various radii of curvature, lens cavities can be created to produce lenses of various powers.

A lens cavity was created by placing a concave giass mold with a radius of curvature of 407.20 mm 15 and a convex glass mold with a radius of curvature of 65.26 mm into a gasket which provided spacing between the molds of 1.8 mm measured at the center of the cavity. A~ u,d---ately 32 grams of a lens forming monomer was charged into the cavity. The lens forming material used for this test was OMB-91 lens monomer. The reaction cell cont~ining the lens forming material was placed horizontally on a supporting stage such that the plane of the edges of the convex mold were at a distance of approximately 30 mm from the plane of the flash 20 tubes and the cell was à~J~Jlu~hnd~ely centered under the light source.

The back surface of the lens cavity was then exposed to a first series of 5 flashes, with an interval of alJIJIU..ill.a~ly 4 seconds in between each flash. The cell was then turned over and the front surface was exposed to another 4 flashes with intervals of about 4 seconds in between each flash. It is preferable to apply the first set 25 of flashes to the back surface to start to cure the material so that any air bubbles in the liquid monomer will not migrate from the edge of the cavity to the center of the optical zone of the lens. Subsequent to these first nine flashes, the reaction cell was allowed to cool for five minutes in the absence of any activating radiation in the above-described FC-104 chamber. To cool the reaction cell, air at a te~ . ,alulG of 71.4 degrees F and at a flow rate of app, o,.-...ately 15 to 25 scf per minute was applied to the back surface and air at a lGIIIp~,. alul G of 71.4 30 degrees F and at a flow rate of a~l oxillld~ely 15 to 25 scf per minute was applied to the front surface of the cell.
The back surface of the lens cavity was then dosed with one more flash and returned to the cooling chamber for four minutes.

Next, the cell was exposed to one flash on the front surface and cooled in the cooling chamber for 35 seven minutes. Then the cell was exposed to one flash on the front surface and one flash on the back surface and cooled for three minutes. Next. the cell was exposed to two flashes on the front surface and two flashes on the back surface and cooled for four and a half minutes. The cell was then exposed to five flashes each to the back surface and front surface, and the gasket was removed to expose the edges of the lens. A strip of polyethylene film hll~ ,llated with photoinitiator (Irgacure 184) was then wrapped around the edge of the lens, and the cell CA 022~1649 1998-10-13 was exposed to another tlve tlashes to the ~-ront surtace and tl~teen ~lashes to the back surtace. I'he back surface of the cell was then placed on the conductive therrnal in-mold postcure device (i.e., "bean bags" filled with glass beads sitting on a hot plate at approx. 340 ~ F) as described previously (see conductive heating example above) for a time period of 13 minutes, after which the glass molds were removed from the finished lens. The finished 5 lens exhibited a distance focusing power of -6.16 diopters and a +2.55 bifocal add power, had excellent optics, was aberration-free, was 74 mm in diameter. and had a center of thickness of I .7 mm. During the cooling steps, a small surface probe thermistor was positioned against the outside of the gasket wall to monitor the reaction.
The results are summarized below.

Dose :lapsed Time From ¦ Gasket Wall "ose (min) I ~ emperature (F) 5 flashes to back surface and 4 flashes to front surface ~ ~ ~lot recorded Not recorded 2 78.4 3 77.9 4 76.9 75.9 I flash to back surface 0 Not recorded 76.8 2 77.8 4 77.8 I flash to front surface 0 Not recorded 79.4 2 81.2 3 81.l 4 79.7 78.7 6 77.5 7 77.4 I flash to front surface and I flash to back surface 0 Not recorded 78.8 2 78.8 3 78.0 2 flashes to front surface and 2 flashes to back surface 0 Not recorded 80.2 2 79.8 3 78.3 4 76.7 4.5 76.3 CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 FURTHER IMPROVEMENTS
IMPROVED ULTRAVIOLET LENS CURING APPARATUS

FIG.30 depicts a schemp~ic view of an embodiment of an ultraviolet lens curing apparatus 400. The d~ )a~llUS preferably includes a first light generator 402 and a second light ~,~ucld~ 404 for generating and directing ultraviolet light towards lens cell 52. First light generator 402 is preferably conr,~,u..,d to direct ultraviolet light toward a first mold member of the lens cell, and second light generator 404 is preferably configured to direct ultraviolet light toward a second mold member of the lens cell. The light generators 402 and 10 404 may be medium pressure mercury lamps for consinl-o~ y directing ultraviolet light towards the lens cell or may be strobe light sources for delivering pulses of ultraviolet light to the lens cell. In an embodiment, the strobe light source is a xenon source having a flash tube made of quartz. In an alternate embodiment, the strobe light source is a xenon source having a flash tube made from, for example, borosilicate.

The d~)~JalalUS may include shutter system 950 (shown in Fig. 7) and programmable logic controller 952.
The shutter system is preferably operable to block at least a portion of the ultraviolet light directed toward at least one of the mold members. Programmable logic controller 952 is preferably coupled to the shutter and adapted to activate the shutter system. The shutters are preferably adapted to extend to block passage of ultraviolet light toward the lens cell and are preferably adapted to retract to allow passage of the ultraviolet light toward the lens cell.

Apparatus 400 preferably includes an air manifold 406 that may s~llJs~ .ti~lly surround irradiation chamber 407. Air distribution device 94 is preferably disposed on the surface of the air manifold to direct air toward the non-casting face of at least one of the mold members. The irradiation chamber preferably comm~mi-~tP~ with air plenum 412, which directs "emuent air" away from the irradiation chamber. As described herein, "effluent air" is taken to mean air that has contacted at least one of the mold members to remove heat from the lens forming material contained within the mold cavity. The lens cell is preferably secured within a lens holder of lens drawer 410 prior to being inserted into the irradiation chamber. The lens drawer may be inserted within and removed from the irradiation chamber and is preferably adapted to form a subst:~nti~lly airtight seal with the air manifold when inserted into the irradiation chamber.

Apparatus 400 preferably includes a first cooling assembly 414 and a second cooling assembly 416 for reducing the l~-lllJ~,Ialul~; of the air (and preferably cooling the air to a II,III~ alUIe below ambient t. .ll~.dlule) before it is passed from air distribution device 94 to the lens cell. FIG.32 depicts a cross-sectional view of the - 35 irradiation chamber and the cooling assemblies. Irradiation chamber 408 is preferably enclosed with 5~1,5~ lly airtight seals to inhibit or prevent cooling air from escaping from the chamber. In an embodiment, members 420 and 422 may be positioned on the air distribution devices to form a substPnti~lly airtight seal. Member 420 is p",f, .al,ly disposed between light generator 402 and the first mold member, and member 422 is preferably disposed between light generator 404 and the second mold member. Members 420 and 422 may be plates and are preferably subst~nti illy lldllS~Jall,lll to the ultraviolet light delivered from light E~,nC.Ial~U~ 402 and 404, CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 respectively. In an embodiment, members 402 and 404 are ~ lly clear borosilicate glass. In an alternate embodiment, members 402 and 404 are light diffusers for diffusing the ultraviolet light directed to the lens cell.
The light diffusers are preferably made of borosilicate glass that has been sandblasted to "frost" the glass. In an alternate embodiment, member 402 and 404 may be made from quartz glass.

In an embodiment, cooling assemblies 414 and 416 are thermoelectric cooling systems. Cooling assembly 414 may be used to cool air directed toward the first mold member, and cooling assembly 416 may be used to cool air directed toward the second mold member. The cooling assemblies are preferably sized to cool the air to a l~ Illpelalule between about 0~C and about 20~C.
Cooling assembly 414 preferably includes a thermoelectric module 422 for creating a l~ ,lalulc differential to allow the air to be cooled to below ambient t~ Jclalul~. An exemplary thermoelectric module is shown in FIG.33. The thermoelectric module is preferably connected to a DC power source 440. The thermoelectric module is preferably a semiconductor wafer and preferably includes a pluralitv of semiconductor 15 pn-couples disposed between a pair of ceramic plates 448 and 450 cont~ining met~lli7Ption 446. The pn-couples are preferably connected thermally in parallel and electrically in series. The thermoelectric module may be a single-stage or cascade module. When the thermoelectric module is cont~c~Pd to the DC power source, a ~h~ ~ on (i.e., "the Peltier effect") occurs whereby heat is absorbed on cold side 448 and heat is ~liecir~t~d from hot side 4S0. It is to be understood that the flow of current may be reversed to cause side 448 to dissipate 20 heat while side 450 absorbs heat.

The publication entitled "An Introduction to Thermoelectrics", available from Tellurex Corp. of Traverse City, Michigan discusses such thermoelectric modules and is inco.~,u,dt~d by reference as if fully set forth herein. The p~nphl~-t entitled "A Thermoelectric Bible on How to Keep Cool", available from Supercool 25 Corp. of Minneapolis, Minnesota also describes a thermoelectric module and is hlCOI,uulal~.d by reference as if fully set forth herein.

In FIG. 31, the side of the thermoelectric module facing upwards is the hot side. Cooling assembly 414 preferably includes a heat sinl; 428 coupled to the hot side to facilitate the di~cir~tion of heat from the 30 thermoelectric module. The heat sink may be directly coupled to the hot side or the heat sink may be indirectly coupled to the hot side via a member having a relatively high thermal conductivity. In FIG.31, the heat sink is indirectly coupled to the hot side by conductive block 424. Incl-l~tif~n 426 preferably subs,~ ly surrounds the thermoelectric module and the conductive block. In an embodiment, a fan 434 is used to direct air across heat sink 428 to increase the rate of heat dissipation from the thermoelectric module. The heat sink preferably 35 includes a plurality of fins which serve as a heat transfer surface.

The cold side of the thermoelectric module is preferably coupled to a cold side heat sink 430 serving to absorb heat to cool the air directed toward the lens cell. The cold side heat sink may be located within air conduit 453 and preferably contains a plurality of fins through which the air is passed to cool it.

CA 022~1649 1998-10-13 Cooling assembly 416 preferably includes second thersnoelectric module 423, second conductive block 425, second hot side heat sink 429. and second fan 435. each of which may operate in the manner as described above for the elements included within cooling assembly 414. In an alternate embodiment, cooling assemblies 414 and 416 may be ind~. .d~ ly operable to allow air directed toward the first mold member to have a different Ic.,~ ,.alul~ than air directed toward the second mold member.

A first blower 432 is preferably configured to direct air through air conduit 453, which communicates with air distribution device 94a. Second blower 433 is preferably configured to direct air through air conduit 454, 10 which comml~ni~ates with air distribution device 94b. As described herein, a "blower" is taken to mean any device operable to drive a fluid such as air through a conduit. The first blower preferably drives air that is distributed across the non-casting face of the first mold member. The second blower preferably drives air that is .I;all ;but~,d across the non-casting face of the second mold member. EMuent air that has contacted the non-casting face of at least one of the mold members is preferably passed through air plenum 412 and to blowers 432 15 and 433 for recycling to air distribution devices 94a and 94b. Each of the thermoelectric modules is preferably sized to cool about 1-30 cubic feet per minute of heated emuent air to a ~C.ll~,l,.aLul~ of about 0-20~C.

In an alternate embodiment, the cooling assemblies may be used to reduce the temperature of the recirculated air to ambient te~llp~.dlull; or a te.lllJ~,.a~ulc~ above ambient temperature. The cooling assemblies may 20 be activated when the cooling air exceeds a predetermined temperature level above ambient temperature.

The thermoelectric cooling system has been found to operate more quietly, efficiently, and reliably than some conventional cooling systems. Recirculating the effluent air through the closed cooling loop tends to reduce the heat duty on the cooling system, since the effluent air in air plenum 412 preferably has a temperature less than 25 ambient t~,-ll~Jc-aLul~.

In an embodiment, a control panel 418 is operable to manually or a~lton~tir~lly control operation of ap~Jala~ 400. The control panel may include an electronic controller for automatic control of svstem variables and a digital display 415 in(lir~ting the ~ .. alul ~ of the cooling air at various locations in the air conduits, 30 irradiation chamber. and air plenum. The control panel is preferably adapted to receive electronic signals from t~_lllp.,.aluli sensors 460, 462, and 464. Cavities may also be formed in conductive blocks 424 and 425 to hold t~,~llp.,.alul~ sensors placed therein. The blowers 432 and 433 may be activated or deactivated and the cooling assemblies may be engaged or di ,e..gaged by switches on the control panel or by a l,. u~. a,-ullable logic controller. The flow rate of air passed across the mold members may be adjusted via the control panel, or the 35 flow rate may be m~in-~in.~d at a constant rate during operation of blowers 432 and 433.

A plu~,all....able logic controller 417 may be housed within the control panel. Controller 417 is preferably adapted to ind~ "d- ."ly control operation of the light gcn~,~a~ol~ 402 and 404 such that ultraviolet light is directed in a plurality of pulses toward at least one of the mold members. The controller 417 is preferably CA 022~1649 1998-10-13 WO 97/39880 PCT~US97/06641 plU~,I .. at le sucn tnat a p.. ,~l~,t~ med tlme elapses hetween each ot tne pulses to op~lmlze tne curmg cycle The controller 417 may be adapted to cause the strobes to fire at ~ ,dct~- ~--ined times through the curing cycle, thereby controlling the rate of polymerization and exothermic heat generation of the lens forming co..,l o~;~ign One l~-u~,~a~u~able logic controller that has been found to perform adequately is the Little Star Mi~ucou1~uller combined with a Relay Six relay board, both co.. e~ially available from Z-World Engineering of Davis, California The strobe firing sequence may be written in Dynamic C l~u~au~n-ing language. The Ultra 1800 White T iehtning photographic strobes, cullnllc~-,;ally available from Paul C. Buff, Incu.~,u.al~d of Nashville, Tennessee, have been found to perform a~'~ 1 IY-10 It is to be understood that ennboAim~ontc of a~ .,dtu~ 400 may be combined with the methods and apparatus of the preferred embodiments described above in previous sections.

IMPROVED LENS CURING APPARATUS EXAMPLE
15 An 80 mm diameter glass 28 flattop bifocal mold with a distance radius of curvature of -5 98 diopters and a +2.50 diopter bifocal add power was sprayed with a mixture of isopropyl aicohol and distilled water in equal parts and wiped dry with a lint free paper towel. The mold was assembled into a silicone rubber gasket in co.,.l :.-a~ion with a cleaned convex mold pss~ ;ng a radius of curvature of +4 1 I diopters A raised lip present on the inner circumference of the rubber gasket provided a spacing of 4.2 mm between the two molds at the 20 center point.

The mold/gasket assembly was posi1ioncd on a filling stage and the edge of the gasket was peeled back to permit the cavity to be filled with 14 4 grams of OMB-91 lens forming cu,..po~ilion, cûllllllc~ui~lly available from the FastCast Corporation of Louisville~ Kentucky. The edge of the gasket was returned to its sealing 25 , ~IA~ I jP with the edges of the molds and excess lens forming CO~ O~;I ;on was vacuumed off the non-casting surface of the back mold with a suction device The filled mold/gasket assembly was transferred from the filling stage to a stage incorporated into a lens drawer of a strobe curing chamber The assembly was irradiated on both its sides according to the exposure cycle shown in FIG 34, which was controlled by a programmable logic controller. The power settings on the strobes were adjusted to maximum power During the irradiation, the lens cell was continnnucly exposed to streams of recirculated air directed by the blower and cooled by the thermoelectric cooling module shown in Figs 31 and 32 At the beginning of the cycle, the air t~ alul~ was 68 degrees F and at the end of the cycle is was measured at 73 degrees F. The air temperature varied during the rest of the cycle up to t..ll~C.dtul~,l as high as 90 degrees F, primarily as a result of 35 the heat added to the system from both the strobe flash lamps and the exothermic heat generated by the lens forming cc....l.o~;l ion. It is anti~ that the up-,...~,..g t~ ,. atures of the air could be reduced to well below ambient ~ ll,u~,~alul~ and the curing cycle could be shortened by use of thermoelectric coolers having a greater capacity than those used in this experiment.

CA 022~1649 1998-10-13 l'he casting cell was turned over in the chamber so that its convex surtace taced upwards and was dosed with 13 flashes to the convex surface and l0 flashes to the concave surface. The casting cell was removed from the strobe chamber, the gasket was stripped from the assembly, and residual uncured material was wiped from the exposed edge of the lens. The cell was returned to the chamber with its concave side facing up and was dosed 5 with an ?~liti -l 13 flashes to the concave surface and l0 flashes to the convex surface.

The non-casting surfaces of both the front and the back molds were placed in contact with thermal transfer pads, c..,ially available from the FastCast Corporation of Louisville~ Kentucky, at tc~ a~u~ of app~oxh~ cly 150 to 200 degrees F for ten minutes. The assembly was removed from the thermal transfer pad 10 and the back mold was removed with a slight impact from an appro~,- idLcly sized wedge. The lens with the front mold attached was placed in a container of water at room lca~l).,.dLulc and the lens separated from the front mold.
The now finished lens was sprayed with a mixture of isopropyl alcohol and water in equal parts and wiped dry.
The finished lens was 4.0 mm thick at the center and was 74 mm in diameter. The lens exhibited a focusing power of +1.98 -0.02D with a bifocal addition power of +2.54D, provided good optical quality, and was non-l S yellow.

IMPROVED LENS CURING PROCESS

When casting an eyeglass lens with ultraviolet light, the gelation pattern of the lens forming cornroci~ic)n 20 may affect the resultant optical quality of the lens. If there are localized flicc~.~a;..uiliPs in the light intPncitiesreceived by the monomer cnn~-qined in the casting cavity during the ea rly stages of the polymerization process, optical distortions may be seen in the finished product. Higher power lenses are, by definition, thicker in certain regions than relatively lower power lenses of the same diameter. The layers of a lens closest to the mold faces of the casting cavity tend to receive a higher light intensity than the deeper layers because the lens forming 25 composition absorbs some of the incident light. This causes the onset of polymerization to be delayed in the deeper layers relative to the outer layers. which may cause optical distortions in the finished product. It is believed that concurrent with this dirf~.c..lial curing rate, there is a difference in the rate of exothermic heat gC~l. .alioll. specifically, the deeper regions will begin to generate heat after the outer regions in the cavity have already cured and the effectiveness of the heat removal may be impaired, contributing to optical waves and 30 distortions in the finished product. This phenomena is particularly observable in high powered positive lenses due to the magnification of such defects.

In an embo~limPnt the lens forrning cu-.-~,o,;lion contained within the casting cavity is exposed to relatively high intensity ultraviolet light for a time period sufficient to initialize the reaction. Irradiation is~5 terminated before the polymerization of the lens forming composition proceeds far enough to generate a amount of heat. This initial relatively high intensity dose preferably subc~qntiqlly uniformly gels the material within the casting cavity such that the difference in the rate of reaction between the inner and outer layers of the lens being cured is reduced. thereby elimin ~in~ the waves and distortions often c.-cuu.-tc.cd when using co.~ .,o.ls low intensity irradiation to initialize the reaction, particularly with high dioptric power positive lenses.

CA 022~1649 1998-10-13 WO 97/39880 PCTrUS97/06641 In an embodiment~ the relatively high intensity dose of ultraviolet light is applied to the lens forming cu~"~osilion in the form of pulses. The pulses preferably have a duration of less than about 10 seconds, preferably less than about 5 seconds, and more preferably less than about 3 seconds. The pulses ,ulcfclably have an intensity of at least about 10 milliwatts/cm2. more preferably at least about 100 milliwatts/cm2, and more preferably still between about 150 milliwatts/cm2 and about 250 milliwatts/cm2. It is preferred that substantially all of the lens forming composition forms into a gel after the initial application of the relatively high intensity ultraviolet light. In an Pmhollim~nt no more than an i..~ i amount of heat is generated by exothermic reaction of the lens forming composition during the initial application of the relatively high intensity ultraviolet I 0 light.

Subsequent to this initial high intensity dose, a second irradiation step is performed in which the material c- nt~inPd within the casting cell is preferably hladial~d for a relatively longer time at a relatively lower intensity while cool fluid is directed at the non-casting surface of at least one of the molds forming the cavity. The cooling 15 fluid preferably removes the exothermic heat gc...,.a~d by the polymerization of the lens forming composition. If the intensity of the ultraviolet light is too great during this second irradiation step, the rate of heat generation will tend to be too rapid and the lens may release prematurely from the casting face of the mold and/or crack.
Similarly, should the rate of heat removal from the lens forming cu",l,oailion be too slow, the lens may release ,~),c."alu,ely and/or crack. It is preferred that the mold/gasket assembly cont~ining the lens forming composition 20 be placed within the cooling envi,u..,,.~.lL as shortly after the initial dose of ultraviolet light as possible.

In an embodiment, the ultraviolet light applied to the lens forming co~ o~ilion during the second irradiation step is less about 350 microwatts/cm2, more preferably less than about 150 microwatts/cm2, and more preferably still between about 90 microwatts/cm2 and about 100 microwatts/cm2. During the second irradiation 25 step, the ultraviolet light mav be applied to the lens forming co",?o~ilion continno~lcly preferred or in pulses. A
trarlch-ce-lt high density polyethylene plate may be positioned between the ultraviolet light gencldlol and at least one of the mold members to reduce the intensity of the ultraviolet light to within the preferred range.

In an embodiment, relatively high intensity ultraviolet light is applied to the lens curing co~ ,osilion in a 30 third irradiation step to post cure the lens subsegu~nt to the second relatively low intensity irradiation step. In the third irradiation step, pulses of ultraviolet light are preferably directed toward the lens forming cu,.l},osilion, although the cu-"pcsilion may be continuously irradiated instead. The pulses preferably have an intensity of at least about 10 milliwatts/cm:, more preferably at least about 100 milliwatts/cm2, and more preferably still between about 100 milliwatts/cm2 and about 150 milliwatts/cm2.
Each of the above-mentioned irradiation steps is preferably pc. ru""cd by directing the ultraviolet light through each of the first and second mold members. The eyeglass lens is preferably cured in a total time of less than 30 minutes and is preferably free of cracks. striations. distortions, haziness, and yellowness.

CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 It is believed that the above-described methods enable the production of whole lenses in prescription ranges beyond those currently attainable with continuous low intensity irradiation. The method can be practiced in the curing of relatively high or low power lenses with a reduced incidence of optical distortions in the finished lens as CO~ Jall_d to conventional methods. It is to be understood that the above-described methods may be used S intlPpPndently or combined with the methods and apparatus of the preferred embodiments described above in the previous sections.

IMPROVED CURING PROCESS EXAMPLE

An 80 mm diameter glass p~u~ sive addition mold with a nominal distance radius of curvature of -6.00 diopters and a +2.S0 diopter bifocal add power was sprayed with a mixture of isopropyl alcohol and distilled water in equal parts and wiped dry with a lint free paper towel. The progressive mold was lenticularized to provide an optical zone 68 mm in diameter along the 180 degree meridian and 65 mm in diameter along the 90 degree meridian. The non-casting face of the mold was mounted to a suction cup, which was attached to a 15 spindle. The spindle was placed on a spinning device provided in the FastCast UX-462 FlashCure Unit, commercially available from the FastCast Corporation of Louisville, Kentucky. A one inch diameter pool of liquid Primer was ~icp~nced into the center of the horizontally positioned glass mold from a soft polyethylene s4ueeze bottle equipped with a nozzle with an orifice diameter of approximately 0.040 inches. The composition of the Primer is ~icrllcced in detail below ~see Scratch Resistant Lens Formation Process Example).
The spin motor was engaged to rotate the mold at a speed of ~ oxhnately 8S0 to 900 revolutions per minute, which caused the liquid material to spread out over the face of the mold. Immediately thereafter, a steady stream of an ~ tion 1l 1.5 to 2.0 grams of Primer material was dispensed onto the casting face of the spinning mold with the nozzle tip posilioned at a 45 degree angle approximately 12 mm from the mold face such that the 2S stream was flowing with the direction of rotation of the mold. The stream of Primer material was directed first at the center of the mold face and then (licp~nced along the radius of the mold face in a direction from the center toward the edge of the mold face. The solvent present in the Primer was allowed to evaporate off for 8 to 10 seconds while the mold was rotated. The rotation was stopped and the Primer coat present on the mold was cured via two t;~lJOa~ tO the ultraviolet output from the medium pressure mercury vapor lamp contained in the UX-30 462 FlashCure unit, totaling .~yl~u~h~alely 300 mJ/cm2.

The spin motor was again engaged and appruxh.,ately 1.5 to 2.0 grams of HC8-H Hard Coat (see description below), commercially available from the FastCast Corporation of Louisville, Kentucky was dia~c.lsed onto the spinning mold in a similar fashion as the Primer coat. The solvent present in the HC8-H was allowed to 3S evayu-aL~ offfor 2S seconds while the mold was rotated. The rotation was stopped and the HC8-H coat was cured in the same manner as the Primer coat.

The mold was removed from the FlashCure unit and assembled into a silicone rubber gasket in combination with a cleaned convex mold possessing a radius of curvature of +2.00 diopters. The raised lip 4û present on the inner circumference of the rubber gasket provided a spacing of 6.3 mm between the two molds at CA 022~1649 1998-10-13 tne center pomt. I ne mola/gas~cet assemt)ly was posltlonea on a ~Illmg stage ana tne eage ot tne gas~et was peeled back to permit the cavity to be filled with OMB-9 1 lens forming co,.,posilion, commercially available from the FastCast Corporation of Louisville, Kentucky. The edge of the gasket was returned to its sealing rel ~ionchip with the edges of the molds and the excess lens forming c-,~"l,o~ilion was vacuumed off the non-5 casting surface of the back mold with a suction device. The filled mold/gasket assembly was placed on a stage inthe UX-462 FlashCure unit and subjected to four exposures of the ultraviolet o utput from the six inch medium pressure mercury vapor lamp, totaling a~,~,,u,.i,,,al~ly 600 mJ/cm2.

I,~,.,.e.1;~l~1y following this initial dose of high intensity ultraviolet light, the assembly was transferred to 10 the FC-132 curing chamber where the casting cell was continuously exposed to streams of air having a t~ Jc.dlul~ of 42 degrees F while being irradiated with very low intensity ultraviolet light for eight minutes. The light intensity measured a~ ruxil~ ly 90 microwatts/cm2 from above plus a~lJlu~illldt~ly 95 microwatts/cm2 from below, which is below the plus lens light distribution pattern called for by the m~nl-f?~ rer. The lamp racks are typically configured to deliver ultraviolet light having an intensity of about 300 microwatt/cm2 for the 15 standard fifteen minute curing cycle. The reduction in ultraviolet light intensity was accomplished by inserting a translucent high density polyethylene plate into the light distribution filter plate slot along with the plus lens light distribution plate. A translucent high density polyethylene plate was positioned between the front mold member and one light distribution plate and between the back mold member and the other light distribution plate.

20 The assembly was ~,bse~ - .. lly returned to the UX-462 FlashCure unit and the non-casting surface of the back mold was exposed to four doses of high intensity UV light totaling ap~lu~i,l,dl~ly 1 150 mJ/cm2. The gasket was stripped from the assembly and residual uncured material wiped from the exposed edge of the lens.
An oxygen barrier strip (polyethylene) was wrapped around the edge of the lens and the mold was exposed to two more doses of high intensity UV light totaling 575 mJ/cm2 to the non-casting surface of the front mold followed 25 by eight more flashes to the non-casting surface of the back mold totaling 2300 mJ/cm2.

The non-casting surface of the back mold was placed in contact with a thermal transfer pad, cu~ ially available from the FastCast Corporation of Louisville, Kentucky, at a t~,.u~ Iuli of a~ i",~lely 150 to 200 degrees F for thirteen minutes. The assembly was removed from the therrnal transfer pad and the back 30 mold was removed with a slight impact from an dp~l U~l iaL~ly sized wedge. The front mold with the lens attached thereto was placed in a container of room te.lllJ~,~a~ulc water and the lens s~;palal~d from the front mold. The now-finished lens was sprayed with a mixture of isopropyl alcohol and water in equal parts and wiped dry. The lens read +3.98 D with an addition power of +2.50, was clear, non-yellow, and exhibited good optics.

The "in-mold" method involves forming a scratch resistant coating over an eyeglass lens by placing the liquid coating in a mold and sllbse~l., ..lly curing it. The in-mold method is advantageous to "out-of-mold"
40 methods since the in-mold method exhibits less oc. u~,~ nces of coating defects manifested as irregularities on the CA 022~1649 1998-10-13 W 097/39880 PCT~US97/06641 anterior surface of the coating. Using the in-mold method produces a scratch resistant coating that replicates the topography and all~oullln~,ja of the mold casting face. However, a problem encountered when using conventional in-mold scratch resistant coatings is that minute "pinholes" often form in the coating. It is believed that the pinholes are caused by either co~ r.l~ on the mold. airborne particles falling on the coating before it is cured, or bubbles formed during the application of tile coating which burst an~i~Ya..ls. The formation of such pinholes is especially prevalent when using a flat-top bifocal mold. such as the one depicted in Fig. 35. As illustrated. an - inAPnt ~ion 452 of the bifocal segment 454 below the main surface 456 of the mold reduces the smoothness of the casting face.
When a coating is spin-coated over the mold face, this in~Pn~tion becomes an obstacle to the even flow of the 10 casting face. The pinhole defects are mainly a problem in tinted lenses because the dye used to tint a lens can penetrate through the pinholes, resulting in a tiny speck of dye visible in the lens.

According to an embodiment of the invention, a first coating cG",posilion, i.e., a polymerizable "primer"
material is passed through a filter and then placed within a mold member having a casting face and a non-casting face. The first coating co"",oailion preferably contains a photoinitiator to make it curable upon exposure to ultraviolet light. The mold member may then be spun so that the first composition becomes diall il,ul~,d over the casting face. The mold member is preferably rotated about a snbstS~nti~lly vertical axis at a speed between about 750 and about 1000 revolutions per minute. Further, a ~licpPncing device may be used to direct an a~ iti~m~l amount of the first cc,..-posi~ion onto the casting face while the mold member is spinning. The ~1icpçncing device preferably moves from the center of the mold member to an edge of the mold member so that the l~lriition~l amount is directed along a radius of the mold member. Ultraviolet light is preferably directed at the mold member to cure at least a portion of the first cc ,--,i~osilion.

A second coating co",?osi~ion may then be placed upon the first composition in the mold member. The second coating is also preferably curable when exposed to ultraviolet light because it contains a photoinitiator.
The mold member is again spun to distribute the second coating composition over the cured portion of the first coating co",poailion. The mold member may also be spun simultaneously while adding the second composition to the mold member. Ultraviolet light is then preferably directed at the mold member to simnlt:~neously cure at least a portion of the second coating CulllpoaiLioll and form a ll ana~Jal ~ combination coat having both coating CU~IIPOa;I;~)nS~ The combination coat is preferably a ~ 1 --a.~lly scratch-resistant coating. The mold member may then be assembled with a second mold member by positioning a gasket between the members to seal them.
Therefore, a mold having a cavity shared by the original two mold members is formed. An edge of the gasket may be displaced to insert a lens-forming cul--posilion into the cavity. The colllbi.laliull coat and the lens-forming material preferably adhere well to each other. This lens-forming colll~,osiliun preferably collllJIiaes a photoiniti~tor and is preferably cured using ultraviolet light. Air which preferably has a l~"U~J~..alUIc; below ambient ~ ,. a~ul ~ may be directed toward a non-casting face of the second mold member to cool the lens-forming composition while it is being cured.

CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 The primer coat preferably co~ ,fi~ts a mixture of high viscosity monomers. a low viseosity, low flashpoint organic solvent, and a suitable photoinitiator system. The solvent may make up about more than 80 %
of the mixture, preferably about 93% to 96%. This mixture preferably has low viscosity and preferably covers any surface irregularity during the spin application, for example the segment line of a flat-top bifocal mold. The 5 low n~l"~O~ solvent preferably c ~/a~Uldt~;~ off relatively quiekly, leaving a thin layer of high viscosity monomer~ cont~iQin~. photoinitiator, whieh eoats the easting faee of the mold. The eured primer coat is preferably soft to allow it to adhere well to the glass mold face. Sinee the primer eoat is soft, it may not possess serateh resistant chala~,hfi;,lics. However, applying a high serateh l~ a"ce hard eoating (i.e., the second eoating col"po~ilion) to the primer eoat preferably results in a seratch resistant combination coat. The hard coat preferably 10 contains a solvent which evaporates when the mold member is rotated to distribute the hard coating over the primer eoat.

In general, the ideal primer material preferably possesses the following cllaldct~ fi~lics: exhibits chemical stability at normal storage cnn.litionc e.g. at room temperature and in the absence of ultraviolet light;
15 flows well on an irregular surface, especially over a flat-top bifocal segment; when cured with a specified ultra-violet dose, leaves a crack-free coating, with a high double bond conversion (approximately greater than 80%);
m~in~inc adhesion with the mold face through the lens forming curing cycle, especially the segment part of the flat-top bifocal mold; and is rhPmir~lly compatible with the hard coat which is suhs~Pqu~prltly applied on top of it, e.g. forrns an optically clear cu".l,i..~tion coat. Even though pinhole defects may be present in either the primer 20 coat or the hard coat, it is highly unlikely that defects in one coat would coincide with defeets of another eoat.
Eaeh eoat preferably eovers the holes of the other eoat, resulting in less pinholes in the combination eoat. Thus, the finished in-mold eoated lens may be tinted using dye without problems ereated by pinholes. lt is also preferably free of craeks, yellowness, haziness, and distortions.

In an embodiment, the gasket between the first mold member and the second mold member may be removed after a portion of the lens-forming material has been eured. The removal of the gasket preferably exposes an edge of the lens. An oxygen barrier having a photoinitiator may be plaeed around the exposed edge of the lens, wherein the oxygen barrier photoinitiator is preferably near an uneured portion of the lens-forming colll~JGsilion. A~riitinn ~1 ultraviolet rays may then be direeted towards the lens to eause at least a portion of the 30 oxygen barrier photoinitiator to initiate reaction of the lens-forrning material. The oxygen barrier p-~;r~ .~,bly prevents oxygen from eontaeting at least a portion of the lens forming e.,...~)o~ilion during exposure of the lens to the ultraviolet rays.

Aecording to one embodiment, a s~lhct~nt~ y solid conduetive heat souree is applied to one of the mold 35 members. Heat may be eonductively transferred from the heat source to a face of the mold member. Further, the heat may be eonduetively ~.a.,~r~l,ed through the mold member to the faee of the lens.

CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 SCRATCH RESISTANT LENS FORMATION PROCESS EXAMPLE

A first coating composition, hereinafter referred to as "Primer", was prepared by mixing the following cu~ ullc.lL~ by weight:

93.87% acetone;
- 3.43% SR-399 (di~-.,..... ~.,,ythritol pentaacrylate), available from Sartomer;
2.14% CN-104 (epoxy acrylate), available from Sartomer;
0.28% Irgacure 184 (l-hydroxycyclohexylphenylketone), available from Ciba-Geigy; and 10 0.28% Darocur 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one) available from Ciba-Geigy.

A second coating composition, hereinafter referred to as "HC8-H" was prepared by mixing the following - , by weight:

15 84.69% 1 -methoxy 2-propanol:
9.45% SR-399 (dipentaerythritol pentaacrylate), available from Sartomer;
4.32% SR601 (ethoxylated bisphenol A diacrylate), available from Sartomer; and 1.54% Irgacure 184 (I-hydroxycyclohexyl- phenyl ketone), available from Ciba-Geigy.

Each of these coating co,l.~.osiIions was prepared by first dissolving the monomers into the solvent, then adding the photoinitiators, mixing well, and finally passing the composition through a one micron filter prior to use.

An 80 mm diameter glass 28 mm flattop mold with a distance radius of curvature of -6.00 diopters and a 25 +2.00 diopter bifocal add power were sprayed with a mixture of isopropyl alcohol and distilled water in equal parts. The flattop mold was wiped dry with a lint free paper towel.
The non-casting face of the mold was mounted to a suction cup, which was attached to a spindle.
The spindle was placed on the spinning device provided in the FastCast UX-462 FlashCure Unit, co~ nc,cially available from the FastCast Corporation of Louisville, Kentucky.
A one inch diameter pool of liquid Primer was tlicp~nced into the center of the horizontally positioned glass mold. The Primer was ~licpenced from a soft polyethylene squeeze bottle equipped with a nozzle having an orifice diameter of approximately 0.040 inches. A spin motor of the spinning device was engaged to rotate the mold at a speed of approximately 850 to 900 revolutions per minute, causing the liquid Primer to spread out over 35 the face of the mold. Immerli~sely thereafter, a steady stream of an ~ iition:~l I .5 to 2.0 grams of Primer material was ~licpl~nced onto the casting face of the spinning mold. l he stream of Primer material was directed onto the casting face with the nozle tip positioned at a 45 degree angle a,u~ xilllaIely 12 mm from the mold face. This poSitioning of the nozle tip made the stream to flow with the direction of rotation of the mold. The stream of CA 022~1649 1998-10-13 WO 97/39880 PCT~US97/06641 rrlmer marerlal was auectea rlrst at tne cemer ot tne mola tace ana tnen alspensea along tne raalus ot tne mola face in a direction from the center toward the edge of the mold face.

The solvent present in the Primer was allowed to evaporate off for 8 to 10 seconds during rotation of the 5 mold. The rotation was stopped and the Primer coat which remained on the mold was cured via two ~A~/O~UI'eS to the ultraviolet output from the medium pressure mercury vapor lamp contained in the UX-462 FlashCure unit, totaling a~ulJIoAilllal~ly 300 mJ/cm2. All light intensity/dosage ulcaault;lllents cited herein were taken with an International Light IL-1400 R~ equipped with an XLR-340B Detector Head, both com..lcrcially available from International Light, Inc. of Newburyport, Upon exposure to the ultraviolet light, the spin motor was again engaged and approximately 1.5 to 2.0 grams of HC8-H Hard Coat, commercially available from the FastCast Corporation of Louisville, Kentucky was ~iicrenced onto the spinning mold in a similar fashion as the Primer coat. The solvent present in the HC8-H was allowed to CVa~JOIa~ off for 25 seconds while the mold was spinning. The rotation was stopped, and the HC8-H
15 coat was cured in the same manner as the Primer coat.

The mold was removed from the FlashCure unit and assembled into a silicone rubber gasket in combination with a cleaned convex mold possessing a radius of curvature of +7.50 diopters. The raised lip present on the inner circumference of the rubber gasket provided a spacing of 1.8 mm between the two molds at 20 the center point. At this point, the mold/gasket assembly was p~ ioncd on a filling stage and the edge of the gasket was peeled back to permit the cavity to be filled with OMB-91 lens forming cc,llll,o~ilion, colllll.c..,ially available from the FastCast Corporation of Louisville, Kentucky. The edge of the gasket was returned to its sealing relationship with the edges of the molds and the excess lens forming colllpo~i1ion was vacuulllcd offthe non-casting surface of the back mold with a suction device.
The filled mold/gasket assembly was 1la..~r~--.d from the filling stage to an FC-132 curing chamber, cOIlllllc,~,ially available from the FastCast Corporation of Louisville, Kentucky. While in the chamber, the assembly was COI-~ i-..-o~-cly irradiated from both sides for a period of 15 minutes at approximately 300 mi~,lu~ a11,/.,"l' from above and at a~u~JIuAhlld~ly 350 microwatts/cm2 from below, according to the minus lens 30 light distribution pattern called for by the mallurh.,1u.~,.. During the irradiation, the casting cell was c....~ u~ly exposed to streams of air having a ~ e. alul~e of 42~ F.

The mold/gasket assembly was ~.k5c~lu- ..lly returned to the UX-462 FlashCure unit. The non-casting surface of the back mold was exposed to four doses of high intensity UV light totaling approximately 1150 35 mJ/cm-. The gasket was stripped from the assembly and residual uncured material was wiped from the exposed edge of the lens. An oxygen barrier strip (polyethylene) was wrapped around the edge of the lens. The mold/gasket assembly was exposed to two more doses of high intensity UV light, wherein 575 mJ/cm2 total was directed to the non-casting surface of the front mold. Sl~b,~ - ."ly, eight more flashes of the UV light were directed to the non-casting surface of the back mold, totaling 2300 mJ/cm .

CA 022~1649 1998-10-13 W O 97/39880 PCTrUS97/06641 The non-casting surface of the back mold was placed in contact with a thermal transfer pad, commercially available from the FastCast Corporation of Louisville, Kentucky, at a lC~IlpC~dlUl~ of approximately 150 to 200~ F for thirteen minutes. The mold/gasket assembly was removed from the thermal transfer pad, and the back mold was removed with a slight impact from an a~ upl ialely sized wedge. The front mold with the lens attached thereto was placed in a container of room temperature water. While within the water, the lens became - separated from the front mold. The now-finished lens was sprayed with a mixture of isopropyl alcohol and water in equal parts and wiped dry.

The lens was positioned in a holder and placed into a heated dye pot for 5 minutes. The dye pot contained a solution of BPI Black, cu...-.-c.~,ially available from Brain Power. Inc. of Miami, Florida. and distilled water at a temperature of a~ u~illlalely 190 degrees F. The lens was removed from the dye pot, rinsed with tap water, and wiped dry. The lens exhibited a total visible light absorbance of a~J~JIU~ Iy 80%. When inspected for cosmetic defects on a light table, no pinhole defects were observed. Further, the tint which had been absorbed by the back surface of the lens was found to be smooth and even.

NON-POLYMERIZABLE SCRATCH RESISTANT COATING PROCESS METHOD

A non-poly,.,cl i~able coating cor"~,osi~ion, hereinafter referred to as "Precoat'', was prepared by mixing 20 the following materials by weight: 99.80% acetone; and 0.20% BYK-300, a slip agent co.. ll.lcrcially available from BykChemie.

An 80 mm diameter glass 28 mm flattop mold with a distance radius of curvature of -6.00 diopters and a +2.00 diopter bifocal add power was sprayed with a mixture of isopropyl alcohol and distilled water in equal parts. The mold was sut~seqllen~ly wiped dry with a lint free paper towel. The non-casting face of the mold was mounted to a suction cup, which was attached to a spindle. The spindle was placed on the spinning device provided in the FastCast UX-462 FlashCure Unit, cOI~ U,l~ ially available from the FastCast Corporation of Louisville, Kentucky.

A spin motor of the spinning device was engaged to rotate the mold at a speed of a~- u~ aLely 850 to 900 revolutions per minute. A steady stream of at".,u,~i.l-alely 2.0 to 3.0 grams of Precoat material was l~ J ~,ced onto the casting face of the spinning mold with the nozzle tip po~i~iùned at a 45 degree angle apl)ru~illlalely 12 mm from the mold face, thereby causing the stream to flow with the direction of rotation of the mold. The stream of Precoat material was directed first at the center of the mold face. The stream was then 11;~ ,ced along the 35 radius of the mold face in a direction from the center toward the edge of the mold face. The intended purpose of the Precoat was to improve the wetting cha. aCLel islics of the glass mold so that the HC8-H material would flow over it more evenly.

CA 022~1649 1998-10-13 The solvent present in the Precoat evaporated offthe spinning mold almost instantly, and a~,~,.u"il..al~ly I .5 to 2.0 grams of HC8-H Hard Coat was fi;~ ed onto the casting face of the spinning mold. The HC8-H
~ard Coat was directed onto the casting face along the radius of the mold face in a direction from the center toward the edge~ The nozzle tip was positioned at a 45 degree angle approximately 12 mm from the mold face S such that the stream was flowing with the direction of rotation of the mold. The solvent present in the HC8-H
was allowed to el~a~l)la~ off for 25 seconds while the mold was spinning. The rotation was stopped, and the HC8-H COât was cured via two ~lJO:IUl~,5 to the ultraviolet output from the medium pressure mercury vapor lamp c.,..~ ed in the UX-462 FlashCure unit, totaling a~ luxillldlt:ly 300 mJ/cm2.

The mold was removed from the FlashCure unit and assembled into a silicone rubber gasket in combin~tion with a cleaned convex mold pO~F~ .g a radius of curvature of +7.50 diopters. The raised lip present on the inner circumference of the rubber gasket provided a spacing of 1.8 mm between the two molds at the center point. The mold/gasket assembly was positioned on a filling stage and the edge of the gasket was peeled back to permit the cavity to be filled with OMB-91 lens forming composition, c0llllll.,..,;âlly available 15 from the FastCast Corporation of Louisville. Kentucky. The edge of the gasket was returned to its sealing rcl,.l ;c ~ .ip with the edges of the molds. The excess lens forming composition was vacuumed from the non-casting surface of the back mold with a suction device. The filled mold/gasket assembly was l[dllS~ ,d from the filling stage to an FC-132 curing chamber, commercially available from the FastCast Co-~.~-dLiou of Louisville, Kentucky. The assembly was ccmtinll~ cly irradiated from both sides for a period of 15 minutes at approximately 20 300 microwatts/cm2 from above and approximately 350 microwatts/cm2 from below. according to the minus lens light distribution pattern called for by the m~nl-f~ rer. During the irradiation. the casting cell was continlloucly exposed to streams of air having a ~elll~J~,.dlu-~; of 42~ F.

The assembly was ,.lb.f 1~ utly returned to the UX-462 FlashCure unit. The non-casting surface of the 25 back mold was exposed to four doses of high intensity UV light, totaling approximately 1150 mJ/cm2. The gasket was stripped from the assembly, and residual uncured material was wiped from the exposed edge of the lens. An oxygen barrier strip (i.e., polyethylene) was wrapped around the edge of the lens and the cell was exposed to two more doses of high intensity UV light, wherein 575 mJ/cm2 total were directed to the non-casting surface of the front mold. Eight more flashes of high intensity UV light followed. The eight flashes exposed the non-casting 30 surface of the back mold to a total of 2300 mJ/cm2.

The non-casting surface of the back mold was placed in contact with a thermal transfer pad at a ,,tu,~: of a~ "d,..ately 150 to 200~ F for thirteen minutes. The assembly was removed from the thermal transfer pad, and the back mold was removed with a slight impact from an dlJ~/rO~JI ;dt-,ly sized wedge. The front 35 mold with the lens attached thereto was placed in a container of room t~ .,.alule water in order to cause the lens to be separated from the front mold. The now-finished lens was sprayed with a mixture of isopropyl alcohol and water in equal parts and wiped dry.

CA 022~1649 1998-10-13 W 097/39880 PCTrUS97/06641 The lens was pos;l ;on~d in a holder and placed into a heated dye pot for 5 minutes. The dye pot cont~inPd a solution of BPI Biack, cu.l....c.~,;ally available from Brain Power. Inc. of Miami, Florida. and distilled water at a ~ llp~alul~ of a~ Ahl,dtcly 190~ F. The lens was removed from the dye pot, rinsed with tap water and wiped dry. The lens exhibited a total visible light absorbance of approximately 80%. When inspected for 5 cosmetic defects on a light table. several pinhole tint defects were observed. They appeared to be in the range of 0.2 mm to 0.05 mm in diameter. However. the tint which had been absorbed by the back surface of the lens was - found to be smooth and even.

Further mo.iifir tion~ and alternative embodiments of various aspects of the invention will be apparent 10 to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forrns of the invention shown and described herein are to be taken as the presently preferred embodim~nt~. Elements and materials may be substit~ for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, 15 all as would be apparent to one skilled in the art after having the benefit of this description of the invention.
Changes may be made in the elements and compositions described herein or in the features or in the sequence of features of the methods described herein without departing from the spirit and scope of the invention as described in the following claims.

Claims (302)

What is claimed is:

1. A method for making a plastic eyeglass lens, comprising:

placing a liquid polymerizable lens forming composition in a mold cavity defined by at least a gasket, a first mold member, and a second mold member;

directing first ultraviolet rays toward at least one of the mold members to substantially cure the lens forming composition so that it forms a lens with a back face, edges, and a front face, and wherein a portion of the lens forming composition proximate the edges of the lens is not fully cured;

removing the gasket to expose the edges of the lens;

applying an oxygen barrier comprising a photoinitiator around the exposed edges of the lens such that at least a portion of the oxygen barrier photoinitiator is proximate lens forming composition that is not fully cured; and directing second ultraviolet rays towards the lens such that at least a portion of the oxygen barrier photoinitiator initiates reaction of lens forming composition while the oxygen barrier substantially prevents oxygen from outside the oxygen barrier from contacting at least a portion of the lens forming composition.

2. The method of claim 1 wherein the lens forming composition is cured to form the lens in less than thirty minutes.

3. The method of claim 1 wherein the first and second ultraviolet rays have substantially similar intensities and substantially similar wavelengths.

4. The method of claim 1, further comprising tinting the lens.

5. The method of claim 1 wherein a portion of the liquid lens forming composition proximate to the gasket remains a liquid after the first ultraviolet rays are directed towards at least one of the mold members.

6. The method of claim 1, wherein a portion of the liquid lens forming composition proximate to the gasket remains a liquid after the first ultraviolet rays are directed towards at least one of the mold members, and further comprising removing at least part of such remaining liquid lens forming composition from the lens after the gasket is removed but before the second ultraviolet rays are directed towards the lens.

7. The method of claim 1 wherein at least a portion of the lens forming composition is cured by application of the second ultraviolet rays.

8. The method of claim 1 wherein the edges of the lens are substantially dry after the second ultraviolet rays are directed towards the lens.

9. The method of claim 1, further comprising directing third ultraviolet rays towards the lens before the gasket is removed.

10. The method of claim 1, further comprising removing the oxygen barrier.

11. The method of claim 1, further comprising cooling the lens or allowing the lens to cool, and then removing the oxygen barrier.

12. The method of claim 1 wherein the oxygen barrier comprises a flexible film that is at least partially transparent to ultraviolet rays.

13. The method of claim 1 wherein the oxygen barrier comprises a stretchable self-sealing film that is at least partially transparent to ultraviolet rays.

14. The method of claim 1 wherein the oxygen barrier comprises polyethylene impregnated with a photoinitiator.

15. The method of claim 1 wherein the lens forming composition comprises less than about 0.15 percent photoinitiator.

16. The method of claim 1 wherein the oxygen barrier comprises a film that was made by applying a solution comprising a photoinitiator to a plastic film.

17. The method of claim 1 wherein the oxygen barrier comprises a film that was made by applying a solution comprising an etching agent and a photoinitiator to a plastic film.

18. The method of claim 1 wherein the oxygen barrier comprises a film that was made by (a) immersing a plastic film in a solution comprising a photoinitiator, (b) removing the plastic film from the solution, and (c) drying the plastic film.

19. The method of claim 1 wherein the oxygen barrier comprises a film that was made by (a) immersing a plastic film in a solution comprising a photoinitiator, (b) removing the plastic film from the solution, (c) applying a solvent to the plastic film, and (d) drying the plastic film.

20. The method of claim 1 wherein the oxygen barrier comprises a film that was made by (a) immersing a plastic film in a solution comprising a photoinitiator and an etching agent (b) removing the plastic film from the solution, (c) applying a solvent to the plastic film, and (d) drying the plastic film.

21. The method of claim 1, wherein the oxygen barrier comprises a plastic film that is less than about 0.025 mm thick.

22. The method of claim 1, further comprising applying a mold member of the mold cavity to a substantially solid conductive heat source and conductively applying heat to a face of the lens by (a) conductively transferring heat to a face of a mold member from the conductive heat source, and (b) conductively transferring heat through such mold member to the face of the lens.

23. The method of claim 1, further comprising:

shaping a flexible heat distributor placed on top of a conductive heat source such that the shape of the heat distributor substantially conforms to a shape of an outside face of a mold member of the mold cavity;

applying the mold cavity to the heat distributor such that the outside face of such mold member is on top of the shaped heat distributor; and conductively applying heat to a face of the lens by (a) conductively transferring heat to a face of a mold member from the conductive heat source, and (b) conductively transferring heat through such mold member to the face of the lens.

24. The method of claim 1, further comprising:

applying a mold member of the mold cavity to a conductive heat source, the conductive heat source comprising a flexible member;

shaping the flexible member such that it substantially conforms to a face of a mold member; and conductively applying heat to a face of the lens by (a) conductively applying heat to a face of a mold member from the conductive heat source, and (b) conductively transferring heat through such mold member to the lens.

25. A method of making a plastic oxygen barrier film comprising a photoinitiator, comprising: (a) immersing a plastic film in a solution comprising a photoinitiator, (b) removing the plastic film from the solution, and (c) drying the plastic film.

26. The method of claim 25, further comprising applying a solvent to the plastic film before drying the plastic film.

27. The method of claim 25 wherein the solution further comprises an etching agent.

28. The method of claim 25, further comprising chemically etching a surface on the plastic film prior to or while immersing the plastic film in the solution.

29. A lens made by the method of claim 1.

30. An oxygen barrier comprising a film that is at least partially transparent to ultraviolet rays, the film adapted to cover at least a portion of a lens edge and inhibit oxygen from contacting the lens edge, and wherein the film is flexible and comprises a photoinitiator.

31. The barrier of claim 30 wherein the film comprises high-density polyethylene.

32. The barrier of claim 30 wherein the film comprises a strip of high density polyethylene, the strip being about .001 to 0.1 mm thick.

33. The barrier of claim 30 wherein the film is less than about .025 mm thick.

34. A method for making a plastic eyeglass lens, comprising:

placing a liquid polymerizable lens forming composition in a mold cavity defined by at least a first mold member and a second mold member;

directing first ultraviolet rays toward at least one of the mold members to cure the lens forming composition so that it forms a lens with a back face, edges, and a front face;

applying a mold member of the mold cavity to a substantially solid conductive heat source; and conductively applying heat to a face of the lens by (a) conductively transferring heat to a face of a mold member from the conductive heat source, and (b) conductively transferring heat through such mold member to the face of the lens.

35. The method of claim 34 wherein the mold cavity further comprises a gasket, and further comprising removing the gasket from the mold cavity after the lens is formed but before conductively transferring heat to the face of the mold member.

36. The method of claim 34, further comprising treating the edges of the lens to cure or remove incompletely cured lens forming material before conductively applying heat.

37. The method of claim 34 wherein heat is substantially uniformly applied to the face of the mold member.

38. The method of claim 34 wherein the heat source comprises a substantially concave element configured to substantially conform to a substantially convex face of a mold member.

39. The method of claim 34 wherein the heat source comprises a substantially convex element configured to substantially conform to a substantially concave face of a mold member.

40. The method of claim 34, further comprising using a heat distributor between the mold member and the heat source.

41. The method of claim 34, further comprising using a heat distributor between the mold member and the heat source to partially insulate the mold member from the heat source, and such that heat is gradually transferred from the heat source to the mold member.

42. The method of claim 34, further comprising thermostatically controlling the temperature of the heat source.

43. The method of claim 34, further comprising using a flexible heat distributor between the mold member and the heat source.

44. The method of claim 34, further comprising using a flexible heat distributor between the mold member and the heat source, and wherein the heat distributor a container containing particles.

45. The method of claim 34, further comprising using a flexible heat distributor between the mold member and the heat source, and wherein the heat distributor comprises a container containing particles of a metal or ceramic material.

46. The method of claim 34, further comprising using a flexible heat distributor between the mold member and the heat source, and further comprising shaping the flexible heat distributor to substantially conform to a face of a mold member.

47. The method of claim 34 wherein heat is only conductively applied to one outside face of one mold member.

48. The method of claim 34 wherein heat is conductively applied through a mold member to the back face of the lens, thereby enhancing cross-linking of the lens forming material proximate to the surface of the back face of the lens.

49. The method of claim 34 wherein heat is conductively applied through a mold member to the back face of the lens, thereby increasing the tintability of the back surface of the lens.

50. The method of claim 34, further comprising tinting the lens.

51. The method of claim 34, further comprising tinting the lens by immersing the lens in a dye solution without substantially agitating the dye solution.

52. A method for making a plastic eyeglass lens, comprising:

placing a liquid polymerizable lens forming composition in a mold cavity defined by at least a gasket, a first mold member, and a second mold member;

directing first ultraviolet rays toward at least one of the mold members to cure the lens forming composition so that it forms a lens with a back face, edges, and a front face;

shaping a flexible member such that it substantially conforms to a face of a mold member;

applying a mold member of the mold cavity to the flexible member, the flexible member being on top of a conductive heat source;

conductively applying heat to a face of the lens by (a) conductively applying heat to a face of a mold member from the conductive heat source, and (b) conductively transferring heat through such mold member to the lens.

53. The method of claim 52 wherein the flexible member is coupled to the conductive heat source.

54. A lens made by the method of claim 52.

55. A system for making a plastic eyeglass lens, comprising:

(i) a lens forming apparatus, comprising;

a first mold member having a casting face and a non-casting face:

a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity; and a light generator for generating and directing ultraviolet light against at least one of the first and second mold members during use; and (ii) a conductive heating apparatus, the conductive heating apparatus being adapted to conductively apply heat to a face of a mold member during use.

56. The system of claim 55, further comprising a heat distributor on top of heat source, the heat distributor being configurable to substantially conform to a non-casting face of a mold member during use

57. The system of claim 55 wherein the conductive lens heating apparatus is adapted to substantially uniformly apply heat to the face of the mold member during use.

58. The system of claim 55, further comprising a heat distributor comprising a substantially concave element configured to substantially conform to a substantially convex face of a mold member during use.

59. The system of claim 55, further comprising a heat distributor comprising a substantially convex element configured to substantially conform to a substantially concave face of a mold member during use.

60. The system of claim 55, further comprising a heat distributor between a non-casting face of a mold member and the heat source during use.

61. The system of claim 55, further comprising a heat distributor between a non-casting face of a mold member and the heat source during use, and further comprising an insulator between the non-casting face of the mold member and the heat source.

62. The system of claim 55, further comprising a heat distributor adapted to partially insulate the mold member from the heat source during use.

63. The system of claim 55, further comprising a heat distributor adapted to gradually transfer heat from the heat source to the mold member during use.

64. The system of claim 55 further comprising a controller connected to thermostatically control the heat source during use.

65. The system of claim 55, further comprising a heat distributor flexibly configurable such that the heat distributor can be shaped to substantially conform to a noncasting face of mold member during use.

66. The system of claim 55 further comprising a heat distributor comprising a container containing particles.

67. The system of claim 55, further comprising a heat distributor comprising a container containing particles, and wherein the particles comprise a metal or ceramic material.

68. The system of claim 55 wherein the conductive lens heating apparatus is adapted to conductively apply heat through a mold member to the back face of the lens during use, thereby enhancing cross-linking of the lens forming material proximate to the surface of the back face of the lens during use.

69. The system of claim 55 wherein the conductive lens heating apparatus is adapted to conductively apply heat through a mold member to the back face of the lens during use, thereby increasing the tintability of the back surface of the lens during use.

70. A method for making an eyeglass lens comprising:

placing a liquid, polymerizable lens-forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming composition comprising a photoinitiator;

applying a plurality of high intensity ultraviolet light pulses to the lens forming composition, at least one of the pulses having a duration of less than about one second;

curing the lens forming composition to form a substantially clear eyeglass lens in a time period of less than 30 minutes.

71. The method of claim 70 wherein at least one of the pulses has a duration of less than about 0.1 seconds.

72. The method of claim 70 wherein at least one of the pulses has a duration of less than about 0.01 seconds.

73. The method of claim 70 wherein the pulses have a sufficiently high intensity such that reaction is initiated in substantially all of the lens forming composition that is exposed to pulses in the mold cavity.

74. The method of claim 70 wherein the pulses have a sufficiently high intensity such that the temperature begins to rise in substantially all of the lens forming composition that is exposed to pulses in the mold cavity.

75. The method of claim 70 wherein the lens forming composition is exposed to a relatively low intensity ultraviolet light while the pulses are applied.

76. The method of claim 70 wherein one side of the mold cavity is exposed to a relatively low intensity ultraviolet light while the pulses are applied to another side of the mold cavity.

77. The method of claim 70 wherein the pulses are applied through both mold members to reach the lens forming composition.

78. The method of claim 70 wherein the lens forming composition is exposed to a relatively low intensity ultraviolet light while the pulses are applied, the relatively low intensity light having an intensity of less than 0.01 watt/cm2, as measured on an outside surface of a mold member of the mold cavity.

79. The method of claim 70 wherein at least one of the pulses has an intensity of at least 0.01 watt/cm2, as measured on an outside surface of a mold member of the mold cavity.

80. The method of claim 70 wherein at least one of the pulses has an intensity of at least 0.01 watts/cm2, as measured on an outside surface of a mold member of the mold cavity.

81. The method of claim 70 wherein at least one of the pulses has an intensity of at least one watts/cm2, as measured on an outside surface of a mold member of the mold cavity.

82. The method of claim 70, further comprising applying sufficient ultraviolet light such that the temperature of the lens forming composition begins to increase, and then waiting at least 5 minutes before applying pulses.

83. The method of claim 70 wherein at least 5 pulses are applied to the lens forming composition.

84. The method of claim 70 wherein at least 10 pulses are applied to the lens forming composition.

85. The method of claim 70 wherein at least 20 pulses are applied to the lens forming composition.

86. The method of claim 70 wherein the eyeglass lens has an average thickness of at least about 1.5 mm.

87. The method of claim 70 wherein the eyeglass lens has an average thickness of at least about 2.0 mm.

88. The method of claim 70 wherein the pulses are substantially discontinuous.

89. The method of claim 70 wherein the pulses are applied such that the lens forming composition cures to form a substantially clear eyeglass lens in a time period of less than 20 minutes.

90. The method of claim 70 wherein the pulses are applied such that the lens forming composition cures to form a substantially clear eyeglass lens in a time period of less than 15 minutes.

91. The method of claim 70, further comprising cooling the mold cavity.

92. The method of claim 70, further comprising applying air to the mold cavity to remove heat from the mold cavity.

93. The method of claim 70, further comprising cooling air and then applying cooled air to the mold cavity to remove heat from the mold cavity.

94. The method of claim 70, further comprising cooling air to between about 0 and 20°C, and then applying the cooled air to the mold cavity.

95. The method of claim 70, further comprising directing air towards the faces of the molds.

96. The method of claim 70 wherein the pulses emanate from a xenon light source.

97. The method of claim 70 wherein the pulses are applied such that the lens forming composition is oversaturated with ultraviolet light during at least one pulse.

98. The method of claim 70 wherein the formed lens has a power greater than positive 2 diopters.

99. The method of claim 70 wherein the formed lens has a power less than minus 4 diopters.

100. The method of claim 70 wherein less than 20 Joule/cm2 of energy is applied to cure the lens forming composition from a liquid into a lens.

101. The method of claim 70 wherein less than 10 Joule/cm2 as measured at 365 nm of energy is applied to cure the lens forming composition from a liquid into a lens.

102. The method of claim 70, further comprising charging a capacitor with energy and then using the charged energy to provide the pulses.

103. The method of claim 70, further comprising applying a relatively low level of ultraviolet light to the lens forming composition while the pulses are being applied and while the pulses are not being applied.

104. The method of claim 70, further comprising applying sufficient ultraviolet light such that the temperature of the lens forming composition forms a gel, and allowing heat to dissipate from mold cavity for at least 5 minutes before applying additional pulses.

105. The method of claim 70, further comprising applying ultraviolet light as a function of the temperature of the lens forming composition.

106. The method of claim 70 further comprising applying ultraviolet light as a function of the temperature of at least a portion the mold cavity.

107. The method of claim 70 further comprising applying ultraviolet light as a function of the temperature of air in or exiting a chamber enclosing the mold cavity.

108. A method for making an eyeglass lens, comprising:

placing a liquid, polymerizable lens forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming composition comprising a photoinitiator; and curing the lens forming composition to form a substantially clear eyeglass lens by applying a plurality of high intensity ultraviolet light pulses to the lens forming composition, the pulses having a duration of less than about one second, the pulses being applied such that the lens forming composition cures to form a substantially clear eyeglass lens in a time period of less than 30 minutes.

109. A method for making an eyeglass lens, comprising:

placing a liquid, polymerizable lens forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming composition comprising a photoinitiator;

applying ultraviolet light at an intensity to the lens forming composition through at least one of the mold members for a selected period of time such that a temperature of the composition begins to increase;

decreasing the intensity of the ultraviolet light to inhibit the temperature of the lens forming composition from increasing to a selected first temperature;

allowing an exothermic reaction of the lens forming composition to increase the temperature of the lens forming composition to a second temperature, the second temperature being less than the selected first temperature;

curing the lens forming composition to form a substantially clear eyeglass lens by: (a) applying ultraviolet light at an intensity to the lens forming composition through at least one of the mold members, and (b) decreasing the intensity of the ultraviolet light; and wherein the eyeglass lens is formed from the lens forming composition in a time period of less than about 30 minutes.

110. The method of claim 109, further comprising repeatedly and alternately performing the following steps to cure the lens forming composition to form a substantially clear eyeglass lens: (a) applying ultraviolet light at an intensity to the lens forming composition through at least one of the mold members, and (b) decreasing the intensity of the ultraviolet light.

111. The method of claim 109 further comprising allowing the lens forming composition to cool to a third temperature, the third temperature being less than the second temperature.

112. The method of claim 109 wherein the intensity of the ultraviolet light is decreased to substantially zero in at least one step.

113. The method of claim 109, further comprising cooling the lens-forming material by directing air toward a noncasting face of at least one of the mold members during the application of ultraviolet light.

114. The method of claim 109 wherein the amount of time that the ultraviolet light remains decreased is varied as a function of a rate of reaction of the lens forming composition in at least one step.

115. The method of claim 109 wherein the amount of time that the ultraviolet light remains decreased is varied as a function of a temperature of the lens-forming composition in at least one step.

116. The method of claim 109, further comprising continuously cooling the lens forming composition by directing air toward a noncasting face of at least one of the mold members, and wherein the air is at a temperature of below about ambient temperature.

117. The method of claim 109 wherein the initial ultraviolet rays are applied toward at least one of the mold members until substantially all of the lens forming composition has reacted beyond its gel point.

118. The method of claim 109, further comprising selecting the intensity of the ultraviolet light to maintain a temperature of the lens forming composition below the second temperature.

119. The method of claim 109 wherein a period of time that the ultraviolet light is decreased is controlled to maintain a temperature of the composition below the second temperature.

120. The method of claim 109, further comprising continuously cooling the lens forming composition by directing air toward a noncasting face of at least one of the mold members, and wherein the air is at a temperature between about 0°C and about 20°C.

121. The method of claim 109 wherein the lens forming composition has a mass of at least about 70 grams, and the selected first temperature is less than about 200°F.

122. The method of claim 109 wherein the lens forming composition has a mass no greater than about 45 grams, and the selected first temperature is less than about 150°F.

123. The method of claim 109 wherein the selected first temperature is a maximum temperature that the lens forming composition would reach without decreasing the ultraviolet light.

124. A method for making an eyeglass lens, comprising:

placing a liquid, polymerizable lens-forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming composition comprising a photoinitiator;

applying first ultraviolet light to at least one of the mold members for a selected first period of time such that a temperature of the lens forming composition begins to increase;

removing the first ultraviolet light from at least one of the mold members, thereby inhibiting the temperature of the composition from increasing to a selected first temperature; and repeatedly and alternately performing the following steps to complete the formation of a lens: (a) applying second ultraviolet light to at least one of the mold members for a selected second period of time and (b) removing the second ultraviolet light from at least one of the mold members for a selected third period of time.

125. The method of claim 124, further comprising cooling the lens forming composition by directing air toward the face of at least one of the mold members

126. The method of claim 124 wherein the lens forming composition is cured to form a substantially clear eyeglass lens in a time period of less than 30 minutes.

127. A method for making an eyeglass lens, comprising;

placing a liquid, polymerizable lens forming composition in a mold cavity defined by at least a first mold member and a second mold member, the lens forming composition comprising a photoinitiator;

directing ultraviolet light at a first intensity toward at least one of the mold members for a selected first period of time such that a temperature of the composition begins to increase;

decreasing the first intensity of ultraviolet light from at least one of the mold members; and repeatedly directing a plurality of pulses of ultraviolet to the lens forming composition through at least one of the mold members to complete formation of a substantially clear eyeglass lens, at least one of the pulses lasting for a second period of time, and wherein a third period of time exists between application of at least two of the pulses.

128. The method of claim 127 wherein the pulses are directed from a pulse light source to the lens forming composition.

129. The method of claim 127 wherein the pulses are directed from a xenon light source to the lens forming composition.

130. The method of claim 127 wherein the second period is less than about one second.

131. The method of claim 127 wherein the first ultraviolet light is in the form of pulses.

132. The method of claim 127 wherein the first ultraviolet light is in the form of pulses from a xenon light source.

133. The method of claim 127 wherein the first ultraviolet light is in the form of pulses from a pulse light source, and wherein a gel is formed by exposure of the lens forming composition to less than 1 second of ultraviolet light.

134. The method of claim 127, further comprising directing air toward at least one of the mold members to cool the lens forming composition.

135. The method of claim 127, further comprising directing air at substantially ambient temperature toward at least one of the mold members to cool the lens forming composition.

136. The method of claim 1278 wherein the first ultraviolet light is in the form of pulses from a xenon light source, and wherein a temperature increase in the lens forming composition occurs less than about 30 seconds after a first pulse is directed toward at least one of the mold members.

137. The method of claim 128, further comprising reflecting light from a reflecting device and into the lens forming composition.

138. The method of claim 128 wherein the second period is varied as a function of a temperature of the lens forming composition within the mold cavity.

139. The method of claim 128 wherein the third period is varied as a function of a temperature of the lens forming composition within the mold cavity.

140. The method of claim 128 wherein an amount of ultraviolet light per unit of time that contacts the lens forming composition is greater than a maximum amount of ultraviolet light that can be absorbed by the lens forming composition per such unit of time.

141. The method of claim 70 wherein the lens forming composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl.

142. The method of claim 70 wherein the composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl, and at least one polyethylenic-functional monomer containing at least three ethylenically unsaturated groups selected from acrylyl and methacrylyl.

143. The method of claim 70 wherein the composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl, and at least one polyethylenic-functional monomer containing at least three ethylenically unsaturated groups selected from acrylyl and methacrylyl, and an aromatic containing bis(allyl carbonate)-functional monomer.

144. The method of claim 109 wherein the lens forming composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl.

145. The method of claim 109 wherein the composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl, and at least one polyethylenic-functional monomer containing at least three ethylenically unsaturated groups selected from acrylyl and methacrylyl.

146. The method of claim 109 wherein the composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl, and at least one polyethylenic-functional monomer containing at least three ethylenically unsaturated groups selected from acrylyl and methacrylyl, and an aromatic containing bis(allyl carbonate)-functional monomer.

147. The method of claim 127 wherein the lens forming composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl.

148. The method of claim 127 wherein the composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl, and at least one polyethylenic-functional monomer containing at least three ethylenically unsaturated groups selected from acrylyl and methacrylyl.

149. The method of claim 127 wherein the composition comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl, and at least one polyethylenic-functional monomer containing at least three ethylenically unsaturated groups selected from acrylyl and methacrylyl, and an aromatic containing bis(allyl carbonate)-functional monomer.

150. An apparatus for making an eyeglass lens, comprising:

a first mold member having a casting face and a non-casting face;

a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity;

a first pulse light generator adapted to generate and direct a pulse of ultraviolet light toward at least one of the first and second mold members during use; and a controller adapted to control the first pulse light generator such that ultraviolet light is directed in a plurality of pulses toward at least one of the first and second mold members, at least one of the pulses having a duration of less than one second.

151. The apparatus of claim 150 wherein the first pulse light generator is adapted to direct light toward the first mold member, and further comprising a second pulse light generator adapted to generate and direct a pulse of ultraviolet light toward the second mold member.

152. The apparatus of claim 150 wherein the first pulse light generator is adapted to direct light toward the first mold member, and further comprising a second pulse light generator adapted to generate and direct a pulse of ultraviolet light toward the second mold member, and wherein the controller is adapted to control the first and second pulse light generators such that ultraviolet light is directed in a plurality of pulses toward the first and second mold members, at least one of the pulses having a duration of less than one second.

153. The apparatus of claim 150 wherein the first pulse light generator is adapted to direct at least one of the pulses for less than about 0.1 seconds.

154. The apparatus of claim 150 wherein the first pulse light generator is adapted to direct at least one of the pulses for less than about 0.01 seconds.

155. The apparatus of claim 150 the first pulse light generator is adapted to generate and direct pulses with a sufficiently high intensity such that reaction is initiated in substantially all of the lens forming composition that is exposed to pulses in the mold cavity.

156. The apparatus of claim 150 wherein the first pulse light generator is adapted to generate and direct pulses with a sufficiently high intensity such that the temperature begins to rise in substantially all of the lens forming composition that is exposed to pulses in the mold cavity.

157. The apparatus of claim 150, further comprising a relatively low intensity ultraviolet light generator adapted to generate and direct relatively low intensity ultraviolet light towards at least one mold member.

158. The apparatus of claim 150, further comprising a relatively low intensity ultraviolet light generator adapted to generate and direct relatively low intensity ultraviolet light towards one mold member, and wherein the first ultraviolet light generator is adapted to generate and direct ultraviolet light pulses towards the other mold member.

159. The apparatus of claim 150, further comprising a relatively low intensity ultraviolet light generator adapted to generate and direct relatively low intensity ultraviolet light towards one mold member, the relatively low intensity light having an intensity of less than 0.1 watt/ cm2, as measured on an outside surface of a mold member of the mold cavity, and wherein the first ultraviolet light generator is adapted to generate and direct ultraviolet light pulses towards the other mold member.

160. The apparatus of claim 150 wherein the first ultraviolet light generator is adapted to generate and direct ultraviolet light such that at least one of the pulses has an intensity of at least 0.01 watt/ cm2, as measured on an outside surface of a mold member of the mold cavity.

161. The apparatus of claim 150 wherein the first ultraviolet light generator is adapted to generate and direct ultraviolet light such that at least one of the pulses has an intensity of at least 0.1 watt/ cm2, as measured on an outside surface of a mold member of the mold cavity.

162. The apparatus of claim 150 wherein the controller is adapted to apply sufficient ultraviolet light such that the temperature of the lens forming composition begins to increase, and then to control the first ultraviolet light generator such that at least 5 minutes passes before additional ultraviolet light pulses are directed towards at least one of the mold members.

163. The apparatus of claim 150 wherein the first ultraviolet light generator is adapted to generate and direct substantially discontinuous pulses.

164. The apparatus of claim 150 wherein the controller is adapted to apply the pulses such that the lens forming composition cures to form a substantially clear eyeglass lens in a time period of less than 20 minutes.

165. The apparatus of claim 150, further comprising a cooler adapted to cool the mold cavity.

166. The apparatus of claim 150, further comprising a distributor adapted to apply air to the mold cavity to remove heat from the mold cavity.

167. The apparatus of claim 150, further comprising a cooler adapted to cool air to between about 0 and 20 C, and then to apply the cooled air to the mold cavity.

168. The apparatus of claim 150 wherein the first ultraviolet light generator comprises a xenon light source.

169. The apparatus of claim 150 wherein the controller is adapted to control the ultraviolet light generator such that less than 20 Joule/ cm2 of energy is applied to cure the lens forming composition into a lens.

170. The apparatus of claim 150 wherein the controller is adapted to control the ultraviolet light generator such that less than 10 Joule/cm2 as measured at 365 nm of energy is applied to cure the lens forming composition into a lens.

171. The apparatus of claim 150, further comprising a capacitor coupled to the controller and the ultraviolet light generator, the capacitor adapted to supply energy to the ultraviolet light generator to provide the pulses.

172. The apparatus of claim 150, further comprising a temperature monitor in a chamber comprising the mold cavity, the temperature monitor coupled to the controller and being adapted to apply ultraviolet light as a function of a temperature in the chamber.

173. The apparatus of claim 150, further comprising a temperature monitor coupled to at least a portion of the mold cavity, the temperature monitor coupled to the controller and being adapted to apply ultraviolet light as a function of a temperature of at least a portion of the mold cavity.

174. The apparatus of claim 150, further comprising a temperature monitor adapted to monitor the temperature of air in or exiting a chamber comprising the mold cavity, the temperature monitor coupled to the controller and being adapted to apply ultraviolet light as a function of a temperature of air in or exiting a chamber enclosing the mold cavity.

175. The apparatus of claim 150 wherein the first ultraviolet light generator comprises a photostrobe having a quartz tube.

176. A system for making an eyeglass lens, comprising:

a lens forming composition comprising a photoinitiator;

a first mold member having a casting face and a non-casting face;

a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity for the lens forming composition;

a first pulse light generator adapted to generate and direct a pulse of ultraviolet light toward at least one of the first and second mold members during use;

a controller adapted to control the first pulse light generator such that ultraviolet light is directed in a plurality of pulses toward at least one of the first and second mold members, at least one of the pulses having a duration of less than one second; and wherein the system is adapted to cure the lens forming composition to form a substantially clear eyeglass lens in less than 30 minutes.

177. The system of claim 176 wherein the lens forming composition further comprises at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl.

178. The system of claim 176 wherein the composition further comprises at least one polyethylenic-functional monomer containing at least three ethylenically unsaturated groups selected from acrylyl and methacrylyl.

179. The system of claim 176 wherein the composition further comprises an aromatic containing bis(allyl carbonate)-functional monomer.

180. A system for making an eyeglass lens, comprising:

a lens forming composition comprising a photoinitiator;

a mold cavity chamber comprising a first mold member having a casting face and a non-casting face, a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity for the lens forming composition;

a first light generator adapted to generate and direct a ultraviolet light in a first intensity toward at least one of the first and second mold members during use;

a temperature sensor adapted to sense a temperature in the chamber or a temperature of air exiting the chamber;

a controller coupled to the temperature sensor and adapted to control the first light generator such that the first intensity of ultraviolet light directed toward at least one of the first and second mold members is decreased when a temperature measured by the temperature sensor substantially increases; and wherein the system is adapted to cure the lens forming composition to form a substantially clear eyeglass lens in less than 30 minutes.

181. The system of claim 180 wherein the controller is adapted to apply ultraviolet light to the lens forming composition through at least one of the mold members for a selected period of time such that a temperature of the composition begins to increase.

182. The system of claim 180 wherein the controller is adapted to apply ultraviolet light to the lens forming composition through at least one of the mold members for a selected period of time such that the lens forming composition begins to gel.

183. The system of claim 180 wherein the controller is adapted to vary the amount of time that the ultraviolet light remains decreased as a function of temperature sensed by the temperature sensor.

184. The system of claim 180 wherein the lens forming composition has a mass of at least about 40 grams, and the controller is adapted to control the ultraviolet light such that the temperature of the lens forming composition does not exceed about 200°C.

185. The system of claim 180 wherein the lens forming composition has a mass less than about 45 grams, and the controller is adapted to control the ultraviolet light such that the temperature of the lens forming composition does not exceed about 150°C.

186. The system of claim 180 wherein the temperature sensor is adapted to sense the temperature of at least a portion of the mold cavity and to transmit a signal to the controller.

187. The system of claim 180 wherein the temperature sensor is adapted to sense a temperature of air in or exiting the mold cavity and to transmit a signal to the controller.

188. The system of claim 180 wherein the controller is adapted to substantially remove ultraviolet light from at least one of the mold members.

189. The system of claim 180 wherein the controller is adapted to apply and remove ultraviolet light to and from the lens forming composition as a function of a sensed temperature.

190. The system of claim 180 wherein the first ultraviolet light generator comprises a flash light source.

191. The system of claim 180 wherein the first ultraviolet light generator comprises a xenon light source.

192. The system of claim 180 wherein the controller is adapted to apply a plurality of pulses of ultraviolet light to the lens forming composition.

193. The system of claim 180 wherein the controller is adapted to apply a plurality of pulses of ultraviolet light to the lens forming composition, at least one of the pulses having a duration of less than 1 second.

194. The system of claim 180, further comprising a reflector adapted to reflect ultraviolet light into the lens forming composition.

195. The system of claim 180 wherein the first ultraviolet light generator is configured to emanate to the lens forming composition an amount of ultraviolet light per time that is greater than a maximum amount of ultraviolet light that can be absorbed by the lens forming composition per such unit of time.

196. An apparatus for making a plastic lens, comprising:

a first mold member having a casting face and a non-casting face;

a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity;

an ultraviolet light generator adapted to direct ultraviolet light rays toward at least one of the first and second mold members during use;

an ultraviolet light controller adapted to control an intensity of light directed by the ultraviolet light generator;

a light sensor adapted to measure the intensity of light directed by the ultraviolet light generator; and a filter adapted to inhibit light other than ultraviolet light from impinging upon the light sensor.

197. The apparatus of claim 196 wherein the light sensor comprises a photoresistor.

198. The apparatus of claim 196 wherein the light sensor comprises a photodiode.

199. The apparatus of claim 196 wherein the ultraviolet light generator is adapted to receive a signal from the light sensor and vary the intensity of the ultraviolet light directed toward at least one of the mold members as a function of the signal.

200. The apparatus of claim 196 wherein the ultraviolet light generator is adapted to receive a signal from the light sensor and send a selected voltage to the ultraviolet light generator to vary the intensity of the ultraviolet light directed toward at least one of the mold members, the selected voltage varied as a function of the signal.

201. A system for making an eyeglass lens, comprising:

a first mold member having a casting face and a non-casting face;

a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity;

a first light generator for generating and directing ultraviolet light against at least one of the first and second mold members during use;

a first distributor adaptable to direct air toward the non-casting face of at least one of the mold members during use;

a thermoelectric cooling system for cooling the air, the thermoelectric cooling system comprising a first thermoelectric module and being adapted to cool the air; and a first blower for directing air to at least one of the mold members, the blower being adapted to receive effluent air that has contacted the non-casting face of at least one of the mold members and to recycle the effluent air to the distributor.

202. The system of claim 201, further comprising a plate connected to the first distributor to form a substantially airtight seal. the plate being substantially transparent to the ultraviolet light generated by the first light generator.

203. The system of claim 201, further comprising a plate connected to the first distributor to form a substantially airtight seal, the plate comprising substantially clear borosilicate glass and being substantially transparent to the ultraviolet light generated by the first light generator.

204. The system of claim 201, further comprising a light diffuser for diffusing the ultraviolet light, the light diffuser being located between the first light generator and the first distributor and comprising sandblasted borosilicate glass.

205. The system of claim 201, further comprising a light diffuser adapted to diffuse the ultraviolet light, the light diffuser being connected to the first distributor to form a substantially airtight seal.

206. The system of claim 201, further comprising a quartz plate connected to the first distributor to form a substantially airtight seal, the plate being substantially transparent to the ultraviolet light generated by the first light generator.

207. The system of claim 201 wherein the first light generator is adapted to direct the ultraviolet light toward the first mold member during use, and further comprising a second light generator adapted to direct ultraviolet light toward the second mold member during use.

208. The system of claim 201 wherein the first light generator comprises a photostrobe having a quartz tube.

209. The system of claim 201, wherein the first light generator comprises a photostrobe having a borosilicate tube.

210. The system of claim 201, wherein the first thermoelectric module comprises a plurality of pn-couples disposed between a pair of metallized ceramic plates.

211. The system of claim 201, wherein the thermoelectric cooling system comprises a DC power source.

212. The system of claim 201, wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising a hot side heat sink coupled to the hot side for dissipating heat from the first thermoelectric module.

213. The system of claim 201, wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising a hot side heat sink coupled to the hot side for dissipating heat from the first thermoelectric module, the hot side heat sink comprising a plurality of fins.

214. The system of claim 201, wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising a hot side heat sink coupled to the hot side for dissipating heat from the first thermoelectric module, and further comprising a fan adapted to direct air onto the hot side heat sink to facilitate dissipation of heat.

215. The system of claim 201, wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising a cold side heat sink coupled to the cold side, the cold side heat sink providing a cooling surface for the air directed to at least one of the mold members.

216. The system of claim 201, wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising a cold side heat sink coupled to the cold side, the cold side heat sink providing a cooling surface for the air directed to at least one of the mold members, the cold side heat sink comprising a plurality of fins.

217. The system of claim 201, wherein first thermoelectric module comprises a hot side and a cold side, and further comprising a hot side heat sink coupled to the hot side for dissipating heat from the first thermoelectric module, and further comprising a conductive block disposed between the hot side and the hot side heat sink.

218. The system of claim 201, wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising a conductive block mounted to the hot side, and further comprising insulation substantially surrounding the first thermoelectric module and the conductive block.

219. The system of claim 201, wherein the first thermoelectric module cools air directed at the first mold member, and wherein the thermoelectric cooling system further comprises a second thermoelectric module adapted to cool air directed toward the second mold member to a temperature between about 0°C and about 20°C.

220. The system of claim 201, wherein the first blower is adapted to recycle the effluent air toward the first mold member. and further comprising a second blower adapted to receive the effluent air that has contacted the non-casting face of at least one of the mold members and to recycle the effluent air toward the non-casting face of the second mold member.

221. The system of claim 201, further comprising an irradiation chamber for containing the mold members during use, the irradiation chamber being substantially airtight.

222. The system of claim 201, further comprising an irradiation chamber for containing the mold members during use, and further comprising an air plenum communicating with the irradiation chamber, the air plenum being configured to direct effluent air from the irradiation chamber to the first blower during use.

223. The system of claim 201, further comprising an irradiation chamber for containing the mold members during use, the irradiation chamber being substantially airtight, and further comprising a lens drawer for positioning the mold members within the irradiation chamber, the lens drawer being adaptable to being inserted within and removed from the irradiation chamber.

224. The system of claim 201, further comprising a shutter system operable to block at least a portion of the ultraviolet light directed toward at least one of the mold members during use, and further comprising an automatic controller coupled to the shutter and adapted to activate the shutter during use.

225. The system of claim 201, further comprising a conductive heating apparatus, the conductive heating apparatus being adapted to conductively apply heat to a face of at least one of the mold members during use.

226. The system of claim 201 wherein the first light generator is adapted to direct ultraviolet light in pulses toward at least one of the mold members, the pulses each lasting less than about one second.

227. The system of claim 201, further comprising a controller to control operation of the light generator such that ultraviolet light is directed in a plurality of pulses toward at least one of the mold members, and wherein the controller is programmable such that a predetermined time elapses between each of the pulses.

228. The system of claim 201, wherein the first thermoelectric module is adapted to cool the air to a temperature between about 0°C and 20°C.

229. A method for making an eyeglass lens, comprising:

placing a liquid, polymerizable lens forming composition in a mold cavity defined at least partially by a first mold member and a second mold member, the first and second mold members each comprising a casting face and a non-casting face, the lens forming composition comprising a photoinitiator;

directing ultraviolet light toward the lens forming composition through at least one of the mold members to form a substantially clear eyeglass lens;

substantially simultaneously with the step of directing ultraviolet light toward the lens forming composition, directing air toward at least one of the non-casting faces of the first and second mold members to remove heat from the lens forming composition; and cooling the air to a temperature below ambient temperature in a thermoelectric cooling system, the thermoelectric cooling system comprising a first thermoelectric module.

230. The method of claim 229, further comprising recycling effluent air that has contacted at least one of the mold members. cooling the effluent air in the thermoelectric cooling system, and directing the cooled effluent air toward at least one of the non-casting faces of the first and second mold members to remove heat from the lens forming composition.

231. The method of claim 229, further comprising directing the ultraviolet light toward the lens forming composition in a plurality of pulses, at least one of the pulses having a duration of less than about one second.

232. The method of claim 229, further comprising directing the ultraviolet light toward the lens forming composition in a plurality of pulses, at least one of the pulses having a duration of less than about one second, and further comprising controlling application of the ultraviolet light with a programmable controller such that a predetermined time elapses between each of the pulses.

233. The method of claim 229 wherein the effluent air is cooled to a temperature between about 0°C and about 20°C.

234. The method of claim 229 wherein the ultraviolet light is directed through both of the mold members to form the eyeglass lens.

235. The method of claim 229 wherein the cooled effluent air is directed toward the non-casting faces of the first and second mold members.

236. The method of claim 229 wherein a first portion of the effluent air is cooled to a first temperature below ambient temperature by the first thermoelectric module, and wherein a second portion of the effluent air is cooled to a second temperature below ambient temperature by a second thermoelectric module, the first temperature being different than the second temperature.

237. The method of claim 229 wherein the first thermoelectric module comprises a plurality of pn-couples disposed between a pair of metallized ceramic plates.

238. The method of claim 229 wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising dissipating heat from the hot side from a hot side heat sink coupled to the hot side.

239. The method of claim 229 wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising directing air onto a hot side heat sink to dissipate heat from the hot side, the hot side heat sink being coupled to the hot side.

240. The method of claim 229 wherein the first thermoelectric module comprises a hot side and a cold side, and further comprising directing air across a plurality of fins contained in a hot side heat sink thereby dissipating heat from the hot side, the hot side heat sink being coupled to the hot side.

241. The method of claim 229 wherein the first thermoelectric module comprises a hot side and a cold side, and wherein the step of recycling the effluent air comprises passing the effluent air across a cold side heat sink coupled to the cold side, thereby cooling the effluent air.

242. The method of claim 229 wherein the first thermoelectric module comprises a hot side and a cold side, and wherein the step of recycling the effluent air comprises passing the effluent air across a plurality of fins contained in a cold side heat sink that is coupled to the cold side, thereby cooling the effluent air.

243. The method of claim 229 wherein first thermoelectric module comprises a hot side and a cold side, and further comprising conductively passing heat from the hot side through a conductive block mounted to the hot side and to a hot side heat sink coupled to the conductive block, and further comprising dissipating the heat from the hot side heat sink.

244. The method of claim 229 wherein first thermoelectric module comprises a hot side and a cold side, and further comprising conductively passing heat from the hot side through a conductive block mounted to the hot side and to a hot side heat sink coupled to the conductive block, and further comprising dissipating the heat from the hot side heat sink, and wherein the conductive block and the thermoelectric module are substantially surrounded by insulation.

245. The method of claim 229 wherein the step of directing ultraviolet light toward the lens forming composition is performed while the mold cavity is located within a substantially airtight irradiation chamber.

246. The method of claim 229, further comprising passing the effluent air from at least one of the mold members to an air plenum, the air plenum communicating with a blower, and further comprising recirculating the effluent air with the blower from the air plenum to the non-casting face of least one of the mold members.

247. The method of claim 229, further comprising operating a shutter to block at least a portion of the ultraviolet light directed toward at least one of the mold members, thereby directing ultraviolet light toward at least one of the mold members in a pulse having a duration of less than about one second.

248. A method for making an eyeglass lens, comprising the steps:

placing a liquid, polymerizable lens forming composition in a mold cavity defined at least partially by a first mold member and a second mold member, the lens forming composition comprising a photoinitiator;

directing a plurality of pulses of ultraviolet light toward the lens forming composition through at least one of the mold members to initiate reaction of the lens forming composition, at least one of the pulses having an intensity of at least about 10 milliwatts/cm2;

subsequent to the step of directing the plurality of pulses toward the lens forming composition, directing ultraviolet light of a second intensity toward the lens forming composition through at least one of the mold members to form a substantially clear eyeglass lens, the second intensity being less than about 350 microwatts/cm2; and substantially simultaneously with the step of directing ultraviolet of a second intensity toward the lens forming composition, directing air onto a non-casting face of at least one of the mold members to remove heat from the lens forming composition.

249. The method of claim 248, wherein at least one of the pulses has an intensity of at least about 100 milliwatts/cm2.

250. The method of claim 248, wherein at least one of the pulses has an intensity of between about 100 milliwatts/cm2 and about 150 milliwatts/cm2.

251. The method of claim 248, wherein the second intensity is less than about 150 microwatts/ cm2.

252. The method of claim 248, wherein the second intensity is between about 90 microwatts/ cm2 and about 100 microwatts/ cm2.

253. The method of claim 248, wherein the ultraviolet light is directed from an ultraviolet light generator toward the lens forming composition, and further comprising positioning a translucent high density polyethylene plate between the ultraviolet light generator and at least one of the mold members to reduce an intensity of the ultraviolet light to the second intensity.

254. The method of claim 248, wherein the step of directing the plurality of pulses toward the lens forming composition comprises forming at least a portion of the lens forming composition into a gel.

255. The method of claim 248, wherein the step of directing the plurality of pulses toward the lens forming composition comprises forming substantially all of the lens forming composition into a gel.

256. The method of claim 248, wherein a substantial amount of heat is generated by exothermic reaction of the lens forming composition only after the step of directing ultraviolet light of the second intensity toward the lens forming composition.

257. The method of claim 248, wherein the ultraviolet light having the second intensity is directed toward the lens forming composition substantially continuously.

258. The method of claim 248, wherein the ultraviolet light having the second intensity is directed toward the lens forming composition in pulses, and wherein at least one of the pulses has a duration of less than one second.

259. The method of claim 248, wherein the eyeglass lens is cured in a total time period of less than about 30 minutes.

260. The method of claim 248, wherein the eyeglass lens is substantially free of cracks, striations, distortions, haziness, and yellowness.

261. The method of claim 248, further comprising, subsequent to the step of directing ultraviolet light of the second intensity toward the lens forming composition, directing a second plurality of pulses of ultraviolet light toward the lens forming composition to form the eyeglass lens, at least one of the second plurality of pulses having an intensity of at least about 10 milliwatts/cm2.

262. The method of claim 248, further comprising cooling the air to a temperature below ambient temperature prior to directing the air onto the non-casting face of at least one of the mold members.

263. The method of claim 248, further comprising cooling the air to a temperature between about 0° C and about 20° C prior to directing the air onto the non-casting face of at least one of the mold members.

264. The method of claim 248, wherein the air is directed onto the non-casting faces of both the first and second mold members.

265. The method of claim 248, wherein the step of directing the plurality of pulses toward the lens forming composition comprises directing pulses of ultraviolet light through each of the first and second mold members.

266. The method of claim 248, wherein the step of directing ultraviolet light of a second intensity towards the lens forming composition comprises directing the ultraviolet light through each of the first and second mold members.

267. The method of claim 248, wherein the pulses are directed from xenon light source, and wherein the ultraviolet light having the second intensity is directed from a mercury vapor lamp.

268. The method of claim 248, wherein the lens forming composition comprises (a) at least one polyethylenic-functional monomer containing at least two ethylenically unsaturated groups selected from acrylyl and methacrylyl, and (b) an aromatic containing bis(allyl carbonate)-functional monomer.

269. The method of claim 248, wherein the eyeglass lens has a dioptric power of at least about ~ 2.00D and is substantially free of distortions, striations, cracks, haziness. and yellowness.

270. The method of claim 248, wherein the eyeglass lens has a dioptric power of less than about ~ 2.00D and is substantially free of distortions, striations, cracks, haziness, and yellowness.

271. A method for making an eyeglass lens, comprising:

placing a first coating composition within a mold member, the mold member comprising a casting face and a non-casting face, the coating composition comprising a photoinitiator and being curable upon exposure to ultraviolet light;

spinning the mold member to distribute the first coating composition over the casting face;

directing ultraviolet light at the mold member to cure at least a portion of the first coating composition;

placing a second coating composition within the mold member, the second coating composition comprising a photoinitiator and being curable upon exposure to ultraviolet light;

spinning the mold member to distribute the second coating composition over the portion of the first coating composition that has been cured;

directing ultraviolet light at the mold member, thereby curing at least a portion of the second coating composition and forming a substantially clear combination coat comprising at least a portion of each of the first and second coating compositions;

assembling the mold member with a second mold member to form a mold having a cavity between the mold members;

placing a lens-forming composition within the cavity, the lens-forming composition comprising a photoinitiator and being curable upon exposure to ultraviolet light; and directing ultraviolet light at the mold to cure at least a portion of the lens-forming material to form a lens, and wherein the combination coat adheres to the cured portion of the lens-forming material.

272. The method of claim 271, wherein the combination coat is curable to form a substantially scratch-resistant coating.

273. The method of claim 271, wherein the cured portion of the first coating composition comprises a pinhole defect, and wherein the second coating composition substantially covers the pinhole defect.

274. The method of claim 271, further comprising applying dye to the lens to color the lens.

275. The method of claim 271, wherein the first coating composition substantially adheres to the non-casting face of the mold member.

276. The method of claim 271, wherein the second coating composition is curable to form a substantially scratch-resistant hardcoat.

277. The method of claim 271, wherein the first coating composition further comprises an organic solvent and a monomer comprising at least one ethylenically unsaturated group selected from the group consisting of acrylyl and methacrylyl.

278. The method of claim 271, wherein the second coating composition further comprises an organic solvent and a monomer comprising at least one ethylenically unsaturated group selected from the group consisting of acrylyl and methacrylyl.

279. The method of claim 271. further comprising preparing the first coating composition by dissolving at least one monomer in an organic solvent, the monomer comprising at least one ethylenically unsaturated group selected from acrylyl and methacrylyl, the solvent making up greater than about 80% of the first coating composition, and further comprising passing the first coating composition through a filter prior to placing the first coating composition within the mold member.

280. The method of claim 271, further comprising preparing the second coating composition by dissolving at least one monomer in an organic solvent, the monomer comprising at least one ethylenically unsaturated group selected from acrylyl and methacrylyl, the solvent making up greater than about 80% of the second coating composition, and further comprising passing the second coating composition through a filter prior to placing the second coating composition within the mold member.

281. The method of claim 271, wherein spinning the mold member to distribute the first coating composition over the casting face comprises spinning the mold member about a substantially vertical axis at a speed between about 750 and about 1000 revolutions per minute.

282. The method of claim 271, wherein spinning the mold member to distribute the second coating composition over the casting face comprises spinning the mold member about a substantially vertical axis at a speed between about 750 and about 1000 revolutions per minute.

283. The method of claim 271, further comprising directing an additional amount of the first coating composition onto the casting face of the mold member while the mold member is spinning.

284. The method of claim 271, further comprising directing an additional amount of the first coating composition onto the casting face of the mold member from a dispensing device while the mold member is spinning, and wherein the dispensing device moves relative to the mold member in a direction from a center of the mold member to an edge of the mold member such that the additional amount is directed along a radius of the mold member in a direction from the center of the mold member to an edge of the mold member.

285. The method of claim 271, wherein the step of placing the second coating composition within the mold member is performed simultaneously with the step of spinning the mold member to distribute the second coating composition over the portion of the first coating composition that has been cured.

286. The method of claim 271, wherein the mold is a flat top bifocal mold comprising a segment line, and wherein the first coating composition has a sufficiently low viscosity to be distributed over the segment line by the spinning of the mold member.

287. The method of claim 271, wherein the first coating composition comprises a solvent, and wherein substantially all of the solvent is evaporated during the step of spinning the mold member to distribute the first coating composition over the casting face.

288. The method of claim 271, wherein the second coating composition comprises a solvent, and wherein substantially all of the solvent is evaporated during the step of spinning the mold member to distribute the second coating composition over the portion of the first coating composition that has been cured.

289. The method of claim 271, wherein the first coating composition comprises a solvent, and wherein a substantial portion of the solvent is evaporated during the step of spinning the mold member to distribute the first coating composition over the casting face.

290. The method of claim 271, wherein the second coating composition comprises a solvent, and wherein a substantial portion of the solvent is evaporated during the step of spinning the mold member to distribute the second coating composition over the portion of the first coating composition that has been cured.

291. The method of claim 271, wherein the combination coat is substantially free of cracks, yellowness, haziness. pinhole defects, and distortions.

292. The method of claim 271, wherein, upon curing, the first coating composition has a double bond conversion greater than about 80%.

293. The method of claim 271, wherein the step of assembling the mold member with a second mold member to form a mold comprises positioning a gasket between the mold members.

294. The method of claim 271, wherein the step of assembling the mold member with a second mold member to form a mold comprises positioning a gasket between the mold members, and wherein the step of placing a lens-forming composition within the cavity comprises displacing an edge of the gasket to expose the cavity and inserting the lens-forming composition therein.

295. The method of claim 271, wherein the second mold member comprises a non-casting face, and further comprising directing air towards at least one of the non-casting faces to cool the mold substantially simultaneously with the step of directing ultraviolet light at the mold to cure at least a portion of the lens-forming material.

296. The method of claim 271, wherein the second mold member comprises a non-casting face, and further comprising directing air towards at least one of the non-casting faces to cool the mold substantially simultaneously with the step of directing ultraviolet light at the mold to cure at least a portion of the lens-forming material, the air having a temperature below ambient temperature.

297. The method of claim 271, wherein the second mold member comprises a non-casting face, and further comprising directing air towards the non-casting faces of the mold members to cool the mold substantially simultaneously with the step of directing ultraviolet light at the mold to cure at least a portion of the lens-forming material.

298. The method of claim 271, wherein the second mold member comprises a non-casting face, and further comprising directing air towards the non-casting faces of the mold members to cool the mold substantially simultaneously with the step of directing ultraviolet light at the mold to cure at least a portion of the lens-forming material, the air having a temperature below ambient temperature.

299. The method of claim 271, wherein the step of assembling the mold member with a second mold member to form a mold comprises positioning a gasket between the mold members, and further comprising:

removing the gasket to expose an edge of the lens after the step of directing ultraviolet light at the mold to cure at least a portion of the lens-forming material to form a lens;

applying an oxygen barrier comprising a photoinitiator around the exposed edge of the lens such that at least a portion of the oxygen barrier photoinitiator is proximate lens-forming composition that is not fully cured;
and directing additional ultraviolet rays towards the lens such that at least a portion of the oxygen barrier photoinitiator initiates reaction of lens forming composition while the oxygen barrier substantially prevents oxygen from outside the oxygen barrier from contacting at least a portion of the lens forming composition.

300. The method of claim 271, further comprising:

applying one of the mold members to a substantially solid conductive heat source; and conductively applying heat to a face of the lens by (a) conductively transferring heat to a face of a mold member from the conductive heat source, and (b) conductively transferring heat through such mold member to the face of the lens.

301. A system for making an eyeglass lens, comprising:

a first mold member having a casting face and a non-casting face;

a second mold member having a casting face and a non-casting face, the second mold member being spaced apart from the first mold member during use such that the casting faces of the first mold member and the second mold member at least partially define a mold cavity; and a first light generator for generating and directing ultraviolet light against at least one of the first and second mold members during use.

302. A method for making an eyeglass lens, comprising:

placing a liquid, polymerizable lens forming composition in a mold cavity defined at least partially by a first mold member and a second mold member, the first and second mold members each comprising a casting face and a non-casting face, the lens forming composition comprising a photoinitiator; and directing ultraviolet light toward the lens forming composition through at least one of the mold members to form a substantially clear eyeglass lens.