US Government As Represented by the Secretary of the Army

Richard G Westrich

Walter E Miller, Jr

William C Pittman

Michael M Jones

Huey F Anderson

The polarization-resolving infrared imager employs the configurations of either first-generation (60 horizontal rows by 1 vertical column of detector elements (pixels)) or second-generation (at least 240 horizontal rows by 4 vertical columns of detector elements (pixels)) infrared imaging detector devices and polarization filters that work in conjunction with the infrared imaging detector devices to separate incoming infrared radiation into portions each having a different polarization orientation. Such polarization separation enables the production of visible images in which various aspects of the scene are differentiated. In the preferred embodiment using the second-generation infrared imaging detector device, polarization-filtering grids are integrated onto the detector. The detector elements in three of the four columns have coupled thereto polarization filtering elements to filter, respectively, horizontal, vertical and 45-degree polarizations of the incoming infrared radiation. Using a scan mirror of sufficient sweep in conjunction with the detector device and the polarization-filtering grid results in one frame of the scene with horizontal polarization, one frame with vertical polarization, one frame with 45-degree polarization and a frame with no polarization distinction, all with one sweep of the scan mirror in real-time scenario. This provides nearly simultaneous infrared scenes at different polarizations from a single cycle of the scan mirror.

Polarization-resolving infrared imager

An optical rangefinder having a transmitter and receiver located closely acent for short range operation allows optimum detection of a target when either or both the target and the rangefinder are moving. An optical window region is established where the transmitter look axis intersects the receiver look axis and is adjustable for providing an output signal when the rangefinder and target are less than approximately ten feet apart. The transmitter may emit either noncoherent or coherent infrared energy. The receiver includes zero crossing detection when a received maximum signal intensity is reached and adequate signal detection means which activates when the signal level exceeds a desired minimum. An output signal is generated when the outputs of these two detection circuits are coincident.

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Huntsville, AL, United States of America

Richard G Westrich