Techniques for optical binary multiplication

Since the late 1930's optics has gradually developed stronger ties with the communication and information sciences of electrical engineering" {4}. The mathematical techniques of frequency analysis developed for communication Systems were applied to analyze optical imaging Systems and then to synthesize desired System transfer functions. The Fourier Transform relationship which exists between the light amplitude distributions at the front and back focal planes of a lens is frequently utilized for both spatial filtering and optical information processing. Since in an optical System two independent spatial variables are available, such a System can handle 2-D opérations such as convolution, crosscorrelation, autocorrélation etc. without having to resort to scanning. Important advances hâve been achieved by the application of Fourier synthesis techniques—the Zernike phase contrast microscope, optical matched filters, various contrast-enhancement techniques, optical character récognition and optical processing of synthetic aperture radar data.