Engineering applications of HOEs manufactured with enhanced performance DCG films.

Abstract

The objective of this research program was the development of the technology for the industrial manufacturing of high efficiency holographic optical elements (HOEs) with predetermined spectral characteristics ranging in format from few square millimeters to square meters. The desired optical properties of holographic materials for specific engineering applications are determined during the making of the film and are modified during the exposure, the development and the post-treatment of the HOE. This technology includes the machine fabrication of precision holographic films with 1 to 50 micron thickness on glass or plastic substrata, the use of filler material to modify the spectral characteristics of HOEs, multiple exposure techniques, contact-copying procedures and chemically and thermally adapted hologram development and post-treatment processes. The technology extends the use of dichromated gelatin (DCG) into the blue and infrared spectral domains and is a viable tool in the control of the holographic properties of the manufactured HOEs. The usefulness of the technology is illustrated with results obtained from existing HOE installations. Design and performance information is presented for manufactured reflection and transmission HOEs that are used in a variety of technical applications, such as: holographic concentrators for photo-voltaic and thermal energy conversion, special collectors for solar photo-chemistry, holographic stacks for day-lighting, glazing and shading in buildings, optical interconnects in multi-chip modules, robotic sensors and holographic beam forming optics for LED applications. Multiple exposures technique is used to record up to four holograms in the same DCG film that are used to generate simultaneously several monochrome or RGB beams.