Semi-physical development of holograms recorded in silver halide emulsions

In the course of experiments on measurement of the effects of processing on nonlinear characteristics of silver halide holograms recorded in Agfa-Gevaert 8E75HD emulsions we found that, under certain circumstances, the AAC developer acted as a semi-physical developer instead of the normal chemical developing action. The developed and fixed holograms were of low optical density (<0.5) and of high diffraction efficiency (up to 15 %). Phase contrast microscopy revealed that very clean phase gratings were obtained. This effect of the AAC developer was due to the replacement of one of its components, sodium carbonate of "purest grade" with that of "for analysis grade" of the same company.