An analysis is presented of the nonlinear effects of holographically recording discrete image points on a phase recording material. The analysis is restricted to thin, two- and three-beam holographic gratings recorded on a material that exhibits a linear phase shift vs exposure. Harmonics, intermodulation noise, and small signal effects are considered. Experimental measurements were carried out for three-beam holographic gratings and diffuse object holograms recorded on photopolymer recording materials. Intermodulation noise is found to be a serious limitation for discrete image point holograms, because this noise cannot be spatially separated from the desired image points. Intermodulation noise can be reduced by increasing the reference-to-object beam irradiance ratio and by reducing the diffraction efficiency. Photopolymer gratings with 50-dB signal-to-intermodulation noise ratio were obtained with diffraction efficiency greater than 1/10% at beam irradiance ratios of 400:1. The image contrast of photopolymer holograms of diffuse objects is compared with the image contrast reported for bleached silver halide emulsions.
J. A. Jenney, "Nonlinearities of Photopolymer Holographic Recording Materials," Appl. Opt. 11, 1371-1381 (1972)