Lenses for lamps can improve the quality of the light emitted through lens by interacting with the light bulb. Photoluminescent dyes as well as non-photoluminescent dyes may be incorporated into a polycarbonate lens in order to shift the chromaticity of the light source. Further, design features such...http://www.google.de/patents/US20040095779?utm_source=gb-gplus-sharePatent US20040095779 - Automotive Headlamps with Improved Beam Chromaticity
