WO1981002216A1

WO1981002216A1 - Process and equipment for recording and displaying laser interference images

Info

Publication number: WO1981002216A1
Application number: PCT/HU1981/000006
Authority: WO
Inventors: J Toth; N Kroo; A Csaji
Original assignee: Mueszeripari Muevek Lab; J Toth; N Kroo; A Csaji
Priority date: 1980-01-26
Filing date: 1981-01-26
Publication date: 1981-08-06
Also published as: HU182793B; EP0044327A1; EP0044327A4; JPS57500209A

Abstract

Process and equipment relate to recording and displaying stationary or moving laser interference and so-called preholographic, respectively, images or image sequences in a predetermined order of sequence. The essence of the process lies in that the images or image sequences to be displayed are produced by the proper formation of the single surficial parts of the plate and the sequential illumination of said parts by the laser light. In case of moving images or image sequences either the plate or the bundle of laser is suitably moved... The essence of the equipment lies in, that the equipment is provided with a laser source, an intercepting screen and between the laser source and the intercepting screen there is a plate arranged. By means of optical elements (e. g. lenses and lens systems) arranged between the plate and the screen and the laser source, respectively, the interference images can be further intercepted.

Description

PROCESS AN D EQUIPMENT FOR RECORDING AND DISPLAYING LASER INTERFERNCE IMAGES

Technical Field of the Invention

The invention relates to a process and an equipment for recording and displaying stationary or moving laser interference images or image sequences in a predetermined order of succession. Background of the invention

As it is well known, for the mankind light has always played an important role in the acquisition of informations and different light effects could be often found among the means of artistic expressing. Accordingly, it is not surprising at all, that the new light sources, the lasers, representing one of the most important scientific results of our era, have been also incorporated into the line of said neans. As a natter of fact, the lasers do not represent more, than light sources in general, however, they are having special properties, being quite different from those of the usual light sources.

The interest for these special light sources has rapidly increased on behalf of the technicians and nonprofessionals. The fact, in so far as the lasers became the centre of interest, may be explained by their special properties being not only different from the traditional ones, but being ever so much better, The most characteristic features of the laser light are the extensive orientation, the monochromatic character, and the resulting considerable coherence, as well as the high light-output, which can be concentrated into a narrow oriented monochromatic beam of light. The nurmerizcal values characterizing the main properties of the lasers can vary within limits in dependence of the type of the laser, establishing the possibility of application in a wide circle.

In particular, the monochromatic i.e. unicoloured beam of light and the intense coherence connected to the sane, with other words the capacity for interference, are representing the special characteristics, which may yield beyond the wide field of application - certain effects, which are approaching several expressing means of the fine arts of the present era, simultaneously enlarging the circle of said expressing means.

The lasers, as new-type light sources became w ide spread in a short time in the different fields of science and technics. This process has been continuously perceptibl At the same time, the possibility of the application of the laser light-effects in spectacular culture was formulated, which could be qualified for satisfying an ever widening mass demand.

Recently, all over the world the spectacular effects to be obtained by means of the lasers became mostly popular in particular in the show-and entertaining business and per formances. The common characteristics lie in, that the unresolved bundles of the laser light are moved by means of different optical elements onto intercepting screens fe.g. the cupola of the planetarium or an auditorium). The specta cular effect is obtained by the rays of light of the lasers of different colours; by dynamics, size and number of the moving light spots. The result is a singular, unrepeatable inprovized light-phenomenon. A process is known, in course of which the laser interference image, the holography, is used for the control of photomats. Let us illuminate an object: the light being diffracted by the same is carrying an information about the given object. This information is carried by the anplitude and phase of the light-wave, i.e. by the complex amplitude of the light-wave. In order to be able to record the complete information coming from the illuminated object, the phase itself has to be also recorded. Taking into consideration, that only a given light intensity can be detected, in course of the traditional photography the information carried by the phase gets lost.

The problem can be aived by the holography. Interference is established between the wave arriving from the object and the so-called reference-wave and the interference image obtained in such a manner is recorded (photographed). Since the phases of the two waves are playing a role in the formation of the interference image, indirectly the phases are also recorded. From the aforesaid an other significant advantage of the holography becomes obvious. That is to say, the light coming from every point of the object, arrives to every single point of the recording substance, accordingly, even the very small part of the recording substance is carrying informations about the entirely of the object. Disclosure of the invention

The aim set for the invention has been to develop an equipment, which is well suitable for the production and repeated display of laser interference images yielding an artistic spectacle of lasting value for the observers. The stationary or moving laser interference images produced by the equipment can be optionally magnified, while the images or image sequence can be displayed in different colours, directly or indirectly, using one or more laser sources.

Accordingly, the task to be solved by the invention may be characterized by the composition of suitable stationary or moving laser interference images or image sequences in a predetermined order of succession, by recording and by the direct or indirect display of said images or image sequence.

The invention is based on the recognition that similarly to the range of tones to be recorded on gramophone records, the optical formations carrying the image informations can be also recorded and read by means of the laser light and in this way direct or indirect display becomes possible; it goes without saying, that in case of moving images either the plate and/or the bundle of laser light is to be moved. Brief description of the drawings

The invention is described in detail by the way of examples only, with reference to preferred embodiments, illustrated in the accompanying drawings, wherein:

Figure 1 is showing one of the embodiments of the invention, Figure 2 and 3 are showing other embodiments of the equip ment according to the invention, Figure 4 is showing the cilindrically bent plate according to the invention with the rotated mirror, Figures 5 to 7 are showing some embodiments of the disc shaped plates according to the invention, Figure 8 is showing the embodiment of an oblong plate accord ing to the invention,

Figure 9 is showing the equipment according to the invention having been arranged in an auditorium, and Figures 10 to 12 are showing further embodiments of the invention. Referring to Figure 1, the equipment according to the invention consists of the laser-light source 1, the plate 2, the motor 3. the diaphragm 4 and the intercepting screen 9. After having opened the diaphragm 4, the bundle of light arrives via the plate 2 to the intercepting screen and the magnified image of the image-element arranged on the plate 2 will be displayed on the screen. The minute motor 3 is slowly rotating the plate having been fixed onto its axle, with a low number of revolutions. The pla te 2 has the shape of a disc and the image elements are arranged beside each other, e.g. along concentrical circles. When the laser light is passing through the transparent material with a non-plain surface, an interference image is obtained, on which light and dark strips being of the same colour, as the laser light - are alternating in form of lines. Accordingly, the figure obtained and displayed on the screen 9 is actually the special photograph of the surface-part having been trans illuminated by the laser ray, from which - in knowledge of the physical relations describing its formation - the shape of the surface can be recontructed by means of calculations, by the aid of the Fourier-analysis.

In Figure 2 a further preferred embodiment of the equipment according to the invention is to be seen, at which the laser light 1 is led through the cylindrically bent plate 8, by applying furhter optical elements, to the screen 9. The intermediate optical elements are the prism 5, the mirror 6 and the rotating mirror 7. At the embodiment under discussion the plate is expediently bent to a cylindrical form and its surface is formed in such a manner, that while the laser light beam is travelling around the cylinder jacket, the sequence of the interference images having been previously planned and tried - may be displayed in the screen. The projected sequences of the in terference images are travelling around the walls of the auditorium.

Figure 3 is showing the cylindrically bent plate 8, the mirror 6, the rotating mirror 7 which is fixed onto the axle of the motor 3, while the projected inter ference image appears on the intercepting screen 9.

The most important features of the laser light are the extense orientation, the monochromatic character and the resulting coherence. In dependence of the laser type the numerical values characterizing said main features of the lasers can vary within wide limits, enabling the wide-spread application of the solution according to the invention. By using the appropriate optical element, by the aid of mirrors or prisms one plate can be simulta neously transilluminated by more laser light bundles 1. In such a manner the continuous coherent monochromatic light of the lasers can be formed into interference image processes, yielding a new and uncommon view for the observer. In Figures 4 to 7 some preferred embodiments of the plate according to the invention are to be seen. The relation between the projected interference image and the relief of the plate can be defined by an unambi guous mathematical correlation, concretely by the Fourier transformation. The laser ray produces the special "pho tograph" of the transilluminated material, sinultaneously concealing the structure which can be normally observed by our usual way of seeing. Although, a fortunate accident has promoted our invention, the image appearing on the screen is not an accidental result after all. The rich network of interferences include a variety, rainging from the explosion of the core to the mysterious spatial construction of linear rhythms interlacing with an exact accuracy. The closing surface of the material is fighting against the strings of light - and the string of light is undergoing a transformation. Something quite new was born, something which could be produced exclusively by means of the laser, simultaneously selection, reproduction and organization into a texture of spectacles becomes pos sible. This monochromatic and at the same time coherent ray, the quickly spreading means of modern science and up--to-date industry, is representing unquestionally a special phenomenon of the present era. The coherent light of the photons emerging from the excited atoms, having been concentrated into a narrow bundle, becomes the means of the organized images.

As a result of the visual analytical activity the fundamental surface forms of the single image elements and the belonging characteristic laser interference images can be well defined. One has th know what kind of optical medium with a special surfacial formation belongs to the laser interference images of high spectacular value, that is to sa y , the interference images of high spectacular value and the belonging single surfacial elements of the optical medium are to be entered into a catalogue.

Cataloguing may take place by using diaohotos, diapositives or photo-negatives, respectively, the photocopies made from the same. The coloured diapoεitives prepared insuch a manner yield the possibility of the simple projection of the interference images without a laser either in form of the simple projecting of the slides or as diaporamas using two or more projectors. By changing the floating period respectively, by the proper change of light intensity the diapositives induce the impression of the motion of the image.

Based on this mode of cataloguing the image-processes of different characters can be designed complying to an A-D sector each of the plates in Figures 4 to 7). The single A-D sectors may be prepared of different transparent materials or substances with a reflecting surface, so e.g. glass, plexiglass, synthetic materials, crystals, while the single sectors may be fixed to each other by glueing. The disc thus obtained may be reproduced by using quite simple means. As it becomes obvious from our specification, on the analogy of the gramophone records a quite new genre, the image-record and the connected interference view has been created; a multitude of image elements may be stored, which can be repeatedly displayed at any optional time.

Since the surface of the single sectors can be processed, the formation of the surfacial parts of the sec tors can be performed by etching, grinding, casting or any other technological process.

The aesthetic interference images having been stored on the plates can be displayed on the intercepting screen 9 by means of the laser light. The phasing of the projected image does not depend on the distance between the plate and the intercepting screen 9. In course of trans lucence either the plate or the laser light is forwarded, eventually with a changeable speed. In general, it seems to be more simple, if the light bundle remains stationary and the plate is moved in accordance with the desired speed.

In case of a disc-shaped plate moving may be performed by a synchronous minute- or stepping motor with a low number of revolutions. In other cases a motor with a changeable number of revolutions may be expediently used which is moving the plate via an inserted transmission. Transillumination of the plate may be performed along a helical path, in this case double moving has to be provided for (e.g. rotating motion and linear, eventually oscillating motion). Linear moving may be performed by the aid of a gear and a rack fastened on the axle T of the motor.

The spectacle can be improved by using differently coloured or tuned lasers, which are tranεilluminating the same plate or mutually synchronised plates. Synchronization of the plates is essential from the point of view of the realization of the previously designed visual experience, i.e. the plates should be started from an identical angular position and rotated with the required angular speed. In such a manner the imageprocess obtained from the different plates and displayed on the screen may be harmonized and co-ordinated in compliance with a predetermined programs.

In course of designing the visual experience the sequence of the interference images is to be built up inaccordance with a tine diagramme, thus estabilishing the possibility of harmonizing the image with an other aesthetic experience, e.g. music, literature, or eurythmics, resulting in an increased effect. When preparing the time-diagramme, colour dynamics, the character and change of the interference images, the rhythm of motions, eventual stills and coordination with musical effects are to be planned.

The intercepting screen 9 serving for receiving the interference-image should be expediently the white wall of the room, where the performance is taking place, or any material increasing the intensity of the reflected light, e.g. glass-pearl screen. In case of a transparent screen the spectacle can be enjoyed on both sides. Since phasing of the interference images does not depend on the distance between the plate and the screen, the geometrical from of the screen nay take up any optional shape.

The single interference-images, i.e. diaporamas having been recorded on diapositives and the sequence of spectacles projected from the plates may be combined resulting in an enriched spectacle; the series of the stills of interference images may be recorded on a film - expediently by the aid of a film camera and a transilluminating pulse laser of high frequency - in this case synchronisation is imperative; later the film can be projected without using the laser. The films having been recorded in such a manner and assembled with other kind of effects can be well used for producing e.g. science-fiction films.

Figure 9 is showing the equipment according to the invention having been arranged in an auditorium. As an example, two laser sources are shown in the figure, however, their number and colour may be determined in dependence of the image-material to be projected. The laser sour ces may work in continuous operation, but lasers in a pulse operation, working with a high repeating frequency may be also used for the display ofthe image or image sequences. Taking a darkened room as a prerequisite, in dependence of the size of the room, the capacity of the lasers may vary in the range between some mw and 5 to 10 W. By using high-output lasers, large-sized images projected from a large distance may be displayed open-air performances). In a room of the size according to the figure the proper effect may be obtained by using lasers with an output of 10 t o 100 mW . Larger rooms require higher outputs f or obtaining the same effect. By arranging mirrors in the path of the unresolved beam the light may be deflected in the desired direction.

The process and the equipment according to the invention may be used in a comprehensive manner for the static and designed, temporally changing display of the interference images of laser rays of different frequencies, i.e. of different colours. In the future said interference images will surely promote the development of spectacular culture; they can be advantageously used for the purposes of the fine arts, art-craft, propaganda, graphic arts, stage effects, films, etc., e.g. as a background for incmas ing aesthetic experiences.

The spectacle can be repeated by the proper rotation of the plate, it can be stopped, decelarated or accelerated, accordingly, the motion of the image sequences can be optionally influenced. Linear motions, e.g. oscillating motions create further variations.

A further advantage of the solution lies in, that the size of the image obtained can be optionally changed by approaching or withdrawing the plate in relation to the laser source, simultaneously phasing of the image does not change.

When combined with a background music, the spectacle built-up of the single images or image processes is well suitable for original performances. These performances may have different characters as already mentioned before, and by the proper selection of the moving images to be projected onto the environment and the figures and by determining the rhythm of motions, an excellent background may be created for ballets and pantomimes or we nay give full value to the atmosphere of literary performances.

Figure 9 shows a further embodiment of the invention, having means 11 for widening the light beam between the laser source 1 and the plate 2. This embodiment functions as the arrangement in Figure 1, but in the present case a bigger portion of the plate-surface is projected, whereby the richness of the spectacle is increased. The neans 11 for widening the light bean nakes possible, the transilluminated portion of the plate freely to change, e.g. in a range of 1 to 10 mm, whereby the image on the screen is modified accordingly .

A further embodiment is shown in Figure 10, provided with an optical elenent 12, e.g. lens or lens system, between the plate 2 and the screen 9. The optical elenent 12 arranged after the plate 2 projects the surface of the plate onto the screen 9. by neans of the said optical elenent 12, the proportion of the real image to the interference image can be changed rithin wide limits. The so-called preholographic image produced in his way contains both the image of the object and the interferance image, but their proportion changes depending on the projection. The projection depends on the position of the optical elenent 12, lens or lens systen, and by changing the said position, the information content of one of the layers of the plate can be selected out of the information-spectrum deriving from the thickness.

Figure 11 shows an embodiment with an optical element, e.g. an optical grid 13, between the plate 2 and the screen 9. The picture-information recorded on the transilluminated surface of the plate is multiplied by the optical grid 13 along a. stripe and the direction of the multiplication is defined by the position of the grid. This phenomenon is based en the diffraction of light on the grid. The degree of multiplication depends on the intensity of the light and the closeness of the scratches on the grid. The spectacle can be further enriched by using two optical grids. In this case, the picture-information is multiplied not along one stripe, but along two or nore, i.e. three dimensions. The position, of the images can be changed by a relative turning of the optical grids. The picύre-infomation can be concentrated by neans of a lens or lens systen arranged between the grid's) and the screen, onto an optional point of the screen, and various geometric figures, e.g. circle, ellipse, etc., can be formed. If at the sane time the picture-plate is turned, too, the image will pulsate, evoking the appearance of a stereoscopic novenent.

Another possibility is the rotating of the optical grid. (s) round different axes, continuously or periodically. In case of a periodic rotation of the optical grids, the picture-elements projected onto the screen are also noving periodically. When the rotation is continuous, the picture elenents are noving continuously, too. If not only the optical grids but also the picture-plate is rotated simultane ously, the moving picture-elements projected onto the screen are pulsating, making stronger the illusion of the stereoscopic movement.

By applying a laser working on several lines (e.g. ionlasers) and by the separation by neans of a prism after the plate, the image can be displayed simultaneously in different colours. If the prism is arranged before the plate, several images can be displayed simultaneously in different colours. By using the caleidoscope optics, the projected laser image will be multiplied resulting in an absolutely new-type spectacle.

Screens consisting of several layers (net-type screens) can be arranged behind each other, whereby the depth of the image can be multiplied.

By using mirrors, the image can be projected onto any optional surface of the room (a temporal shift is also possible).

The plate itself is made in such a manner, that the artist is composing the spectacle and forms the basic image elements or the negative of the same; from these an optional copy made of a transparent material, e.g. a synthetic material, may be prepared by casting or pressing; the copies may be displayed by means of the equipment according to the invention.

A further possibility is given by leading the projected image through a moving or rotated grid(s), possibly the grids nay move or rotate in opposite directions.

As it is well known, hologrammes are widely used in technical practice. One of the possible applications is the control of photonats, but they are well suitable for fulfilling other tasks. th e sterescopic image obtained in course of recontruction represents a source of aesthetic experience, accordingly, the scope of application is enlarged in this way too.

Claims

WHAT WE CLAIM: IS:

1. Process for recording and displaying stationary or noving laser interference inages or image sequence in a predetermined order of succeεsion, c h a r a c t e r i z e d i n that the image or the image sequences to be displayed are produced by the proper formation of the single surfacial parts of the plate and by the sequential illumination of said parts by a laser light; in vase of moving images or image seσquences either the plate or the bundle of laser is suitably moved.

2. Process as claimed in claim 1, c h a r a c t e r i z e d i n that the plate is made of a transparent material and/or partially or entirely of a material with a reflective surface.

3. Process as claimed in claim 1 or 2, c h ar a c t e r i z e d i n that the plate is illuminated by laser lights of at least two different colours.

4. Process as claimed in any of the claims 1 to 3, c h a r a c t e r i z e d i n that a disc-shaped plate is used, which is rotated by means of a synchronous notor or a motor with a changeable speed.

5. Process as claimed in any of the clains 1 to 3, c h a r a c t e r i z e d i n that the plate is formed as a cylinder jacket or as the mantle of a prism with a polygonal base, at which the illumination is performed by means of the rotating mirror having been arranged in the centre of the cylinder jacket or the mantle of the prism with a polygonal base and by the aid of the laser bundle led onto the rotating mirror.

6. Equipment for performing the process as claimed in claims 1 to 5, for recording and displaying stationary or moving laser interference imageε or image secuences in a predetermined order of succession, c h a r a c t e r i z e d i n that it is provided with a laser source, an intercepting screen and a plate having been arranged between the laser source and said screen.

7. Equipment as claimed in claim 6, c h a r a c t e r i z e d i n that there is a disc-shaped plate provided with a synchronous motor or a motor with changeable speed.

8. Equipment as claimed in claim 7, c h a r a ct e r i z e d i n that between the laser source and the plate there is an eleσrically or mechanically controlled diaphragm.

9. Equipment as claimed in claim 6 or 8, c h a r a c t e r i z e d i n that the plate is formed as a cylinder jacket and in the centre of the same a mirror provided with a motor is arranged and between the mirror and the diaphragm there is a prism, preferably a pentaprism and a light-reflective mirror.

10. Equipment as claimed in any of the claims 6 to 9, c h a r a c t e r i z e d in that between the laser source and the plate there are means for widening the light bundle.

11. Equipment as claimed in any of the claims

6 to 10, c h a r a c t e r i z e d i n that between the plate and the intercepting screen there is an optical element, e.g. lens.

12. Equipment as claimed in any of the claims 6 to 11, c h a r a c t e r i z e d i n that the laser source is working on several lines, e.g. it is an ionlaser.

13. Equipment as claimed in any of the claims 6 to 12, c h a r a c t e r i z e d , i n that between the light source and the plate and/or the plate and the intercepting screen there are caleidoscopic ootics arranged.

14. Equipment aε claimed in any of claim 6 to 13. c h a r a c t e r i z e d i n that between the plate and the laser source and/or between the plate and the intercepting screen there is at least one optical grid.

15. Equipment as claimed in any of the claims 6 to 14, c h a r a c t e r i z e d i n that the intercepting screen consists of at least two tranlucent nets having been arranged in a predetermined distance from each other.

16. Equipment as claimed in any of the claims 6 to 15, c h a r a c t er i z e d i n that between the plate and the intercepting screen assembled of several parts there is a device for splitting the beam, e.g. a semi-trans lucent mirror.