This paper presents the results of experimental studies of relief-phase holograms produced by introducing an additional bleaching operation into the processing procedure. It shows that it is possible to significantly increase the surface-relief height by the effective modulation of short-wavelength UV radiation in the thickness of the photoemulsion layer by silver compounds. The effect of the residual absorption of light in the gelatin layer on the diffraction efficiency of relief-phase holograms is studied.
S. N. Gulyaev and V. P. Ratushnyi, "Properties of relief-phase holograms produced by processing photographic plates with short-wavelength UV radiation and with two-stage bleaching," J. Opt. Technol. 70, 105-108 (2003)