Scanning aperture partially coherent optical correlator

Claim 2

In an optical correlator for processing an intput signal distorted along its time base which is recorded as a density variation on a film strip moving in a first spatial domain of said correlator, the improvement of a scanning slit of adjustable width positioned adjacent said film strip and repeatedly scanning a portion of this film strip at a speed high as compared to the speed at which this film strip moves in said domain, each scanning cycle producing at the energy detector of said correlator one sample of the partially coherent correlaTion function and repeated scanning cycles developing the full, partially coherent, correlation function.

Claim 3

An optical correlator for processing partially coherent signals comprising, in combination, a first spherical lens; a recording strip having input signal information stored therein as density variations in the transparency of said strip positioned in the object plane of said lens; a light source located on the optical axis of said lens for illuminating an area on said strip with monochromatic coherent light; means for advancing said strip across the optical axis of said lens such that different areas of said strip are illuminated by said light source; a reference strip having the complex conjugate of the Fourier transform of a particular signal recorded thereon as density variations in the transparency of this strip positioned in the back focal plane of said lens; an energy detector; a second spherical lens located on said optical axis, said reference strip being in the front focal plane of said second lens, and said energy detector being in the back focal plane of said second lens; a scanning slit positioned adjacent said recording strip and having an opening as measured along said strip of variable size; and means for repeatedly moving said slit past a portion of said recording strip at a speed higher than the speed of advancement of said recording strip.

Claim 4

An optical correlator for processing partially coherent signals comprising, in combination, a first spherical lens; a recording strip having input signal information stored therein as density variations in the transparency of said strip positioned in the object plane of said lens; a light source located on the optical axis of said lens for illuminating an area on said strip with monochromatic coherent light; means for advancing said strip across the optical axis of said lens such that different areas of said strip are illuminated by said light source; a reference strip having the complex conjugate of the Fourier transform of a particular signal recorded thereon as density variations in the transparency of this strip positioned in the back focal plane of said lens; an energy detector; a second spherical lens located on said optical axis, said reference strip being in the front focal plane of said second lens, and said energy detector being in the back focal plane of said second lens; a scanning slit positioned adjacent said recording strip and having an opening as measured along said strip of variable size; and means for repeatedly moving said slit past a portion of said recording strip at a speed higher than the speed of advancement of said recording strip.

Claim 5

In an arrangement as defined in claim 2 wherein said energy detector is a photomultiplier tube positioned on said optical axis and wherein the setting of said slit corresponds to the opening size thereof which develops a maximum signal in the output of said photomultiplier tube from the movement across said optical axis of a particular portion of said recording strip having input signals stored therein.

Claim 6

In an arrangement as defined in claim 2 wherein the speed at which said slit moves past said recording strip is such that a multiplicity of scanning cycles occurs in the time a particular portion of said recording strip takes to move across said optical axis.