Optical Analog Computers

Abstract

Certain applications of optical devices in digital computers are described, and a general theory of optical analog computers is developed. Certain characteristics of the photographic process make it possible to perform mathematical operations with photosensitive materials, as well as with photocells. These characteristics are: (1) the modulation of light intensities by optically dense films; (2) the addition of densities of superimposed layers; (3) the multiplication of transparencies of superimposed layers; (4) the ability of the photographic emulsion to integrate exposures occurring throughout time or from several sources.Examples of optical methods of calculation are described, and the construction of an optical analog computer for synthesizing the two-dimensional Fourier transform of a function for use in crystal structure determination is described. A new machine giving immediate presentation of the results of two-dimensional Fourier transforms is proposed.