US Government As Represented by the Secretary of the Army

Bobby D Guenther

Juris Upatnieks

Charles R Christensen

Reference scenes stored in a filter set containing an array of sets of suimposed, holographic, matched filters are optically correlated with input images displayed on an optically-addressed, liquid crystal, light modulator 34. In operation, a selected laser diode is energized to direct a polarized light beam through the collimating lens L1 to the reflecting surface of a polarizing beam splitter 35. After reflecting off the beamsplitter surface, the beam is expanded by positive lens L2 and passed to the liquid crystal modulator. There it is modulated by the input image and reflected; after which it is recollimated by positive lens L2, transmitted by the beamsplitter, and directed to a particular array location of the filter set dependent upon which particular laser diode is energized. The filter set is positioned to be in the back focal plane of lens L4 so that the Fourier-transform of the input image is incident on the particularly located, superimposed matched filter at 31. If the Fourier transformed input image corresponds to one of the superimposed matched filters the incident light beam is diffracted by that particular hologram matched filter to form a spot of light at a predetermined array location of a detector array. The optical correlator finds use as a terminal guidance system in guiding a missile to its target.

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Huntsville, Albania

Bobby D Guenther