Spectral evaluation of laboratory-made silver halide emulsions for color holography

Ultra-fine-grain silver halide emulsions with average grain size of around 10 nm were prepared in our laboratory for true color holographic recording. They were spectrally sensitized with various types of cyanine dyes, and their absorption spectra were measured to study the efficiency of sensitization. Their photographic and holographic characteristics were evaluated and discussed in connection with the results of absorption spectrum measurements. Adequately sensitized emulsions showed M-or J-bands in their absorption spectra at the wavelengths of laser beams for exposure. Dye molecules showing no bathochromic shifts of M-bands in emulsion sols contributed very little to spectral sensitization and seemed situated away from silver halide particles. Each of the red, green, and blue holographic gratings recorded on the laboratory-made emulsion plates showed a higher than 50% diffraction efficiency. But some of the best sensitized emulsions did not show the optimum results in diffraction efficiencies.