In a lens-barrel etc. for holding lenses, a thin film composed of a fluororesin compound having a refractive index lower than that of a material constituting the lens-barrel is formed on an inner surface of the lens-barrel, thereby lowering an amount of the reflective light appeared on the inner surface...http://www.google.de/patents/US5353070?utm_source=gb-gplus-sharePatent US5353070 - Lens holder which reduces internal reflections
