STORAGE MECHANISM OF VOLUME PHASE HOLOGRAMS RECORDED IN SILVER-HALIDEEMULSIONS

A relatively simple model for elucidating the holographic storage mech anism in bleached silver halide recording materials is developed. In t his model the storage of holographic gratings includes three separate contributions that are due to silver halide grains, a gelatin matrix, and voids in the gelatin matrix. Linear refractive-index-modulation-ve rsus-exposure responses are assumed for the individual contributions, which are summed to produce the overall diffraction-efficiency (DE)-ve rsus-exposure response. Calculated and experimental results reveal tha t, through reduction of one or more of the contributions to the hologr aphic storage in a composite emulsion system through chemical means, t he maximum achievable DE's increase and may reach 100% in the case of a homogeneous and lossless phase grating. Specifically, the addition o f sulfite or triethanolamine to the processing formulations in a rever sal bleach processing procedure or in a silver halide sensitized gelat in procedure had the effect of increasing the experimental DE's. The c orresponding calculated DE-versus-exposure responses indicate that the se additives suppressed the gelatin tanning or matrix void contributio ns.