Optical correlator using electronic image preprocessing

Claim 1

Apparatus for incoherent optical correlation of a two-dimensional function, comprising: (a) means for generating a first electronic signal representative of said function; (b) means for electronically performing at least one mathematical operation on said first electronic signal to derive a second electronic signal; (c) means for electrically converting said second electronic signal into a two-dimensional spatially and temporally incoherent visual image, said two-dimensional visual image having an associated mathematical image function; (d) imaging means for producing a secondary image of said two-dimensional visual image in an image plane, said second image likewise being spatially and temporally incoherent; (e) means for generating an optical correlation function having (i) first and second lens means arranged with their respective optical axes substantially in alignment, said first lens means being spaced apart from said imaging means such that said image plane and the focal plane of said first lens means coincide, the object of said first lens means being said two-dimensional spatially and temporally incoherent image, and (ii) match optical filter means located between said first and second lens means, said filter means having a random phase distribution and a predetermined transfer function whose amplitude is the square root of the amplitude of said image function; (f) optical detecting means located on the side of said second lens means opposite said filter means and at the image plane of said second lens means for detecting the optical correlation function generated by said first and second lens means and said filter means and generating a third electronic signal representative of said optical correlation function; and (g) electronic analyzer means for analyzing said third electronic signal to determine the amplitude and position of the peak of the optical correlation function.