Diffraction efficiency limitations of holograms recorded in silver-halide emulsions

Experimental results are presented of the diffraction efficiencies of holograms recorded in bleached silverhalide emulsions for varying beam ratio and exposure. It is found that for high beam ratios the diffraction efficiency quickly reaches a relatively low limit and remains nearly constant as the exposure is increased. A model is presented which explains this saturation by a simple relationship between the refractive index modulation and the exposure maxima and minima. The effect of noise gratings on the depletion of the transmitted and diffracted beams is also investigated by measurements at different replay directions and at two different wavelengths.