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Applications of volume holographic diffusers in projection displays

We present a model based on the coupled mode theory and use this model to analyze the diffraction properties of volume holographic diffusers, such as the diffraction efficiency and wavelength sensitivity. Volume holograms of both transmission type and reflection type are analyzed. Besides typical behaviors of Bragg diffraction, we notice several interesting phenomena. For transmission gratings with small diffraction angles, our results predict that the diffraction efficiency exhibits a blue-shift for its maximum value and a dip at the recording wavelength. Also presented is the enhancement of wavelength tolerance for a thin holographic medium, which can serve as a wideband diffuser over the entire visible range. For a thick medium, the wavelength- multiplexed volume holograms recorded with three primary colors, red, green, and blue, are studied, which provide an effective and feasible means of diffusion for color displays.