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Phase holograms in photochromic materials.

The characteristics of phase holograms written into photochromic materials are treated theoretically. A photochromic response function is defined and evaluated for special cases of practical interest. This function describes the basic material response, including the nonlinear effects of varying absorption during the writing process and of saturation. A holographic response function is then defined in terms of the photochromic response function. This function describes the scattering efficiency of holographic gratings written into the photochromic material. The results are presented in a form that relates the holographic properties to the basic material properties. Several cases are evaluated in detail, and it is shown how the results can be used to estimate the characteristics of any given photochromic material as a recording medium for phase holograms.