Improvements to the optical computers for determining the function of a fourier represented by a signal that is variable in time.

摘要

In an optical calculator for a bi-dimensional Fourier transform of a time-variable signal, two sources 10, 12 are modulated spatially along a straight segment corresponding to time and intensity as a function of the value of the signal to be processed. Between these sources and a screen 20 are arranged two masks 22 and 24 with respectively variable transparency. The first source 10 is supplied by a signal which depends solely on the positive parts of the signal to be processed while the illumination function of the second source 12 depends solely on the negative parts of the signal to be processed. The transparencies of the first and second masks vary around a mean value respectively corresponding with the variations of a correlation function and of its opposite. The illumination obtained at each point on the screen is the sum of a parasitic component independent of the position of the point, easily filterable, and of a term corresponding to the Fourier transform sought. IMAGE