Optimization of a fixation-free rehalogenating bleach for BB-640 holographic emulsion

Abstract

Fixation-free rehalogenating bleaching is an interesting for the production of phase holograms. The shrinkage of the emulsion is reduced in comparison with other bleaching methods (reversal bleaching or rehalogenating bleaching with ® xation). In this paper we present experimental results for ® xation-free rehalogenating bleached holograms derived from the novel BB-640, a red-sensitive ultra-® ne grain emulsion from Holographic Recording Technologies. The in¯uence of the potassium bromide concentration in the bleach solution on the ® nal quality of the holograms is also studied. The concentrations of the diå erent components of the bleach solution are adjusted to obtain the highest values of diå raction eae ciency. We show that really high diå raction eae ciencies can be obtained, as high as 84%, when ® xation-free rehalogenating bleached holograms are recorded on BB-640 plates.

Experimental evidence of mixed gratings with a phase difference between the phase and amplitude grating in volume holograms

“…This diffusion process is particularly influenced by the halide concentration in the bleach solution [11]. Although fixation-free rehalogenating bleaches are generally known for creating pure phase holograms [9,[13][14][15][16], the oxidation products of the bleach can give rise to an absorption modulation at high values of exposure and high concentrations of potassium bromide in the bleach bath. Experimental confirmation of this fact can be found in reference [17].…”

“…The ratio X = B/A indicates the relation between the potassium bromide concentration and the oxidizer concentration (potassium dichromate). In previous articles the B/A ratio was optimized in order to take into account different experimental conditions [14,15]. The holograms studied in this paper were bleached with a B/A ratio of 240.…”

Angular responses of the first diffracted order in over-modulated volume diffraction gratings

“…The angle between the normal of the plate and each of the incident beams was 22.5º, so that the 11 spatial frequency of the diffraction gratings was calculated as ∼1200 lines/mm. After exposure the holograms underwent a fixation-free rehalogenating bath [18][19][20] so finally phase volume gratings were obtained. In other works it has been demonstrated that fixation-free rehalogenating bleaching techniques produce phase holograms with high values of the refractive index modulation.…”