15 May 1997 Fabrication of large-format holograms in dichromated gelatin films for sun control and solar concentrators
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Dichromated gelatin layers (DCG) facilitate the design and fabrication of large format holographic optical elements (HOE) of high optical quality and diffraction efficiency. The HOEs are used for the fabrication of spectrally selective solar concentrators and as glazing materials for daylighting and passive sun control in buildings. The suitability of HOEs in these applications depends upon the achievable bandwidth, operating central wavelength, dispersion characteristics and low absorption losses. The HOEs are fabricated on glass or plastic film substrata in a DCG-layer of 5 to 30 micrometer thickness. The layer thickness and the gradient ar precisely controlled during the layer deposition and drying (plus or minus 1 micrometer and 0.1 micrometer/cm for standard layer of 10 micrometer thickness). The production process is based on the fabrication of high quality master holograms that are copied by dry copying procedure. The current manufacturing facilities allow the fabrication of 1 m2 HOEs on glass substratum and a continuous production of HOEs on plastic substratum with a width of 20 cm and length of 50 m. This technology is also used to fabricate holograms for instrumentation optics in metrology and for optical interconnects in multichip modules. The fabricated HOEs exhibit the desired operational characteristics: high diffraction efficiency, small Braggshift, large bandwidth and a central wavelength that may be freely selected over a wide spectral range. In this paper, we present the results from the experimental investigation and theoretical analysis of large number of holograms of the transmissive and reflective types. We discuss the attained angular and wavelength spectra, bandwidths, wavelength shifts and the diffraction efficiencies as functions of the holographic parameters. The HOEs are made for technical applications and are designed to operate in the 300 nm - 1500 m spectral range.
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Christo G. Stojanoff, Christo G. Stojanoff, Hartmut Schuette, Hartmut Schuette, Jochen Schulat, Jochen Schulat, Ralf Kubiza, Ralf Kubiza, Philipp Froening, Philipp Froening, } "Fabrication of large-format holograms in dichromated gelatin films for sun control and solar concentrators", Proc. SPIE 3010, Diffractive and Holographic Device Technologies and Applications IV, (15 May 1997); doi: 10.1117/12.274414; https://doi.org/10.1117/12.274414

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