Abstract: Phase equalization of a phase-distorted multifrequency signal is accomplished by acousto-optic modulating a coherent light beam with the signal taking the optical Fourier transform with the resultant Fourier plane containing all frequency components spatially distributed. A control array, positioned in the Fourier plane and/or local oscillator, contains adjacent elements having their birefringence variable with respect to each other thereby selectively altering the light path length and/or amplitude of each frequency component passing through the element. The resultant transformed image then undergoes optical down conversion to obtain the electrical signal having its phase equalized relative to the distorted input signal.

Abstract: Amplitude equalization of a distorted multifrequency signal is accomplished by acousto-modulating the signal with a coherent light beam and focusing a resultant image on a Fourier plane where the frequency components of the image are spatially distributed. A control array, positioned in the plane, contains adjacent elements having optical filtering properties variable with respect to each other thereby selectively altering the optical amplitude of each image frequency component passing through the elements. The resultant transformed image then undergoes conversion to an electrical signal having its amplitude equalized relative to the distorted input signal.

Abstract: An optical notching filter in which a band of radio frequencies such as the RF input of a radio receiver is an input signal. The input signal modulates a laser beam and the modulated beam is optically Fourier transformed. A programmable optical notching filter spatially filters the electromagnetic interference noise from the transformed beam and the thus filtered beam is optically inverse Fourier transformed. A photo-combining of the filtered beam with a focused laser local oscillator beam down-converts the filtered beam to the original input signal minus electromagnetic interference.

Abstract: An optical notching or filtering system in which a beam of optical radiation is passed through the optical filtering means a multiplicity of times. The optical filtering means has an optical Fourier transform means, a spatial filter, optical inverse Fourier transform means, and a reflector array. After an input optical signal beam undergoes a filtering pass by being directed through the transform means, the filter, and the inverse transform means, the reflector array re-introduces the beam for a multiplicity of subsequent filtering passes. Four embodiments of the system of the invention having various configurations of the reflector arrays for use with one- and two-dimensional spatial filters are disclosed. The various embodiments are set forth as being used in a heterodyning optical notching filter system.