Effect of Pre-hardening on Image Quality of Dichromated Gelatin Phase Hologram

Abstract

It is known that the image quality of dichromated gelatin (DCG) phase hologram strongly depends on pre-hardening. In the present study, we determined Al (III) and Cr in the processed gelatin layer, and gelatin eluted from the gelatin layer during the development, for evaluating the effect of the pre-hardening by alum. It was found that the diffraction efficiency was dominated by the strength of pre-hardening through solubility of the un-exposed parts (dark fringes) rather than that of photo-hardening by exposure, and that the reactivity of gelatin for pre-hardening reaction is one of the most essential factors.