Optical information processing using variable electro-optic spatial filter

Claim 1

An optical information processing system comprising: a variable electro-optic spatial filter comprising an electrooptic medium that exhibits electrically induced birefringence which varies as a function of the intensity of an electric field applied thereacross, a photoconductive medium associated with said electro-optic medium and an electrical blocking layer for preventing charge leakage, said electro-optic medium, photoconductive medium and electrical blocking layer being positioned between two transparent electrodes having means for establishing an electric field thereacross; first lens means for providing to said variable electro-optic spatial filter a first Fourier transform of radiation to be processed; means for projecting an image of a pattern comprising the intended spatial filtering function onto said electro-optic spatial filter to vary the applied electric field across said electro-optic medium according to said pattern for modulating information of predetermined spatial frequency included in said first Fourier transform, to produce a modified form of said first Fourier transform; second lens means for providing a second Fourier transform of said modified form of said first Fourier transform to reproduce a replica of said radiation representative of information to be processed with information of predetermined spatial frequency modified in accordance with the intensity pattern of said applied electric field, sensor means for sensing the modified information pattern positioned after said second lens means for providing the second Fourier transform; digital computer means for analyzing the distribution of light intensity sensed by said sensing means and computing a new pattern for modulating information of predetermined spatial frequency at said filter; and, feedback means for varying the electric field applied across said spatial filter in accordance with the new pattern generated by said digital computer means.