Die Physik des photographischen Prozesses: Physical problems of the photographic process

A survey is given the physical principles of modern photographic processes which still involve to a great extent silver halide photography. Depending on the exposure conditions a certain distribution of illuminating intensity exists at the surface of the photographic layer. Due to absorption and scattering this intensity distribution is changed in the interior of the layer. Several recent investigations establish the relation between some macroscopic properties (as transparency and reflectance) and the optical properties of silver halide. Upon absorption of a few (about 4–6) light quanta a significant and usually stable change of the crystal properties tapes place. This change, which is due to the formation of latent image centres, catalyzes the reduction of the crystal in a solution containing a reducing agent (developer). A discussion of the mechanism of latent image formation considers some new advances in silver halide research, as e.g. foundary layer effects. This so—called chemical ripening canses the formation of traps for electrons and positive holes in the crystal. Experimental as well as theoretical investigations of the kinetics and topography of ripening centre formation and of the action of such centres lead to a deep and nearly complete insight into latent image formation and into the mechanisms of special effects as e.g. solarization, and reciprocity failene. The development of the exposed crystal which involves a number of transport phenomena in the crystal may be thermodynamically discussed as a continuation of the photolytic latent image formation. Finally it is shown that the known properties of the silver halide micro crystals can be used for a theoretical evaluation of the shape of the characteristic curve.