Proceedings PaperThe Development Of Dichromated Gelatin For Holographic Optical Element Applications
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A practical, industrial manufacturing process for holographic optical elements based on dichromated gelatin has now been established to meet the exacting standards and tolerances needed for current Head-Up-Display applications. This process is now also being used to produce holographic optical elements for a number of other applications. The material requirements are very demanding for holographic optical elements of high quality and performance. A better understanding of hologram formation in dichromated gelatin is leading to better control over the performance range which can be achieved. Holographic optical elements whose performance closely matches theoretical models assuming uniform fringe structure will be described as well as examples of holographic optical elements, whose performance can only be described by assuming a non-uniform fringe structure. Such controlled non-uniform fringe structures are advantageous for some applications. Techniques have been developed to produce dichromated gelatin holographic optical elements with a very wide range of characteristics for new applications. High quality reflection holographic optical elements have been produced in gelatin films from less than 5 μ to greater than 100 μ in thickness. A wide range of combinations of diffraction efficiency and bandwidth can now be produced and holographic optical elements can be tuned over the whole visible spectrum and into the near infra-red. Holographic optical elements on plastic substrates have also been made. Dichromated gelatin transmission holographic optical elements have been produced with diffraction efficiencies approaching the theoretical maximum for both planar and Bragg holograms. Applications for both reflection and transmission holographic optical elements are described.