Direct formation of planar holograms and noise gratings at 820 nm in bleached silver-halide emulsions

Experimental results are presented on the efficiency of holographic transmission gratings formed in bleached silver-halide emulsions (Agfa-Gevaert 8E75HD) with illumination at 820 nm. For comparison, data for planar gratings recorded at 780 and 632.8 nm in emulsions that were similarly processed are also given. Measurement of the spectral optical density indicates that the useful holographic recording range extends to 840 nm. We conclude with a comparison of the efficiency of noise gratings formed in this emulsion at 632.8, 780, and 820 nm and a discussion of the implications of these results.