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ABSTRACT
The effects of sulphite ion in holography are complex and depend on the exact processing regime which is used. They result from a combination of two basic mechanisms, the solvation of undeveloped silver bromide grains and reaction with the developer oxidation product.
It is shown that the rate of solution of grains in holographic emulsions is dependent on grain size and that significant amounts of silver can be removed from the emulsion during normal holographic development. The developed silver filaments show evidence of physical development which is less dependent on exposure than has been found previously for other materials.
The reaction with developer oxidation products has an important influence on the photographic contrast and hence the holographic image brightness. Addition of sulphite to metol developers increases contrast and brightness whilst the reverse is predicted for hydroquinone and pyrogallol.