Abstract: Thick holographic films are useful for making multiple recordings in the same volume and for reducing the amount of light diffracted into unwanted orders by a single recorded grating. Dichromated gelatin (DCG) is a material that may be used in thick layers and processed in a way that leads to behavior as a thick hologram. We investigated ways to coat and process layers up to 100 microns thick on glass. We found that the control of the modulation and integrity of the original exposed structure was a formidable task. The angular bandwidth was often smaller than the angular error and the angular error was sometimes a random variable over the surface and volume. Uniformly hardened films were made and exposed to uniform plane waves but the resulting recordings often lacked uniformity in every property but thickness. The lower range of thicknesses was far easier to work with and process than the higher range.!3
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