Abstract

Experimental measurements of the diffraction efficiencies of reflection and transmission holograms recorded in silver halide emulsions reveal an unexpected saturation in the efficiency vs exposure characteristic for high beam ratio recordings at an exposure well below the normal material saturation level. Both planar gratings and diffuse- wave holograms show similiar characteristics; the saturation effect depends on the type of processing used and is particularly significant when a no-fix process is used to minimize emulsion shrinkage. In the latter case the transmitted beam can be almost completely depleted by diffraction from noise gratings, indicating competition at recording between noise modulation and signal modulation, and it is proposed that this is the reason for reduced efficiency in all cases. The relationship between exposure modulation and permittivity modulation is quantified, and a theoretical model of the saturation effects formulated, leading to proposals for reducing detrimental effects and so to increase signal modulation and efficiency.

© 1986 Optical Society of America