An improved optical correlator using a coherent light beam employs a method of adaptive alignment. A test pattern modulates an input spatial light modulator. The modulated beam propagates through passive transforming optical elements to a filter spatial light modulator, which is simultaneously modulated with an independently transformed frequency domain reference. The resulting correlation or coincidence of the optically transformed pattern with the independently transformed reference is processed to yield a feedback signal indicative of any optical misalignment of the optical correlator. The feedback signal drives a beam deflector to compensate by adjusting the path of the coherent beam, thereby improving and maintaining optical alignment of the correlator.