Staring IR-FPA with dither-locked frame circuit
First Claim
Patent Images
1. An imaging system, comprising:
- an entrance aperture for admitting electromagnetic radiation conveying an image of a scene;
a radiation detector array comprised of a plurality of pixels;
a mirror interposed between said entrance aperture and said array for directing the electromagnetic radiation to said pixels;
means for effecting a movement of said mirror with respect to said pixels for moving said scene image from a first selected plurality of pixels to a second selected plurality of pixels and for reading out signals from a currently selected plurality of pixels, the signals resulting at least in part from a detection by the currently selected plurality of pixels of the electromagnetic radiation that conveys the scene image; and
means, having an input coupled to an output of said radiation detector array, for processing said signals to reduce an effect of array fixed pattern spatial noise;
whereinsaid radiation detector array is comprised of circuitry for defining a boundary of the currently selected plurality of pixels and for controlling a readout of the signals from within the boundary of the currently selected plurality of pixels.
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Abstract
An improved imaging technique is disclosed wherein an output from an IR-FPA (16) corresponds to image motion, wherein a scene image stays correlated with the IR-FPA readout, and wherein non-uniformities (e.g., fixed pattern spatial noise) are uncorrelated from frame to frame. The uncorrelated fixed pattern spatial noise is identified and removed by a signal processor, such as a SB-NUC block (24). The scene image is scanned over the IR-FPA by a dither mirror (14) in synchronism with the movement of a frame of pixels (17) on the IR-FPA. Electronics (16a, 16b, 30, 32, 34) are included on the IR-FPA for controlling the scanning and read out of pixels within a currently selected frame.
46 Citations
18 Claims
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1. An imaging system, comprising:
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an entrance aperture for admitting electromagnetic radiation conveying an image of a scene; a radiation detector array comprised of a plurality of pixels; a mirror interposed between said entrance aperture and said array for directing the electromagnetic radiation to said pixels; means for effecting a movement of said mirror with respect to said pixels for moving said scene image from a first selected plurality of pixels to a second selected plurality of pixels and for reading out signals from a currently selected plurality of pixels, the signals resulting at least in part from a detection by the currently selected plurality of pixels of the electromagnetic radiation that conveys the scene image; and means, having an input coupled to an output of said radiation detector array, for processing said signals to reduce an effect of array fixed pattern spatial noise;
whereinsaid radiation detector array is comprised of circuitry for defining a boundary of the currently selected plurality of pixels and for controlling a readout of the signals from within the boundary of the currently selected plurality of pixels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An IR radiation imaging system, comprising:
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an entrance aperture for admitting IR radiation conveying an image of a scene; an IR-FPA comprised of rows and columns of pixels; a mirror interposed between said entrance aperture and said IR-FPA for directing the IR radiation to said pixels; control means having a first output for specifying a pointing direction of said mirror with respect to said pixels, said first output causing said pointing direction to change for moving said scene image over said IR-FPA in a predetermined pattern; said IR-FPA comprising circuitry for specifying the location and boundaries of a frame of pixels as a function of said control means first output and for reading out signals from pixels within the frame, the signals comprising a first desired component representing a detection by the pixels within the frame of the IR radiation that conveys the scene image, and a second, undesired component that includes fixed pattern spatial noise; and scene based non-uniformity correction means, having a first input coupled to an output of said IR-FPA and a second input coupled to a second output of said control means, for processing said signals to substantially eliminate said fixed pattern spatial noise. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for operating an IR imaging system, comprising the steps of:
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scanning an image of a scene over a radiation receiving surface of an IR-FPA in a predetermined pattern; reading out IR radiation-induced signals from a frame of IR-FPA pixels within a larger pixel field, the signals being read out of a frame of pixels whose position is moved in synchronism with the scanning of the image whereby the scene image remains correlated with the IR-FPA readout, and whereby non-uniformities are uncorrelated from frame position to frame position, wherein the reading out the frame is accomplished at least in part by electronic circuits that comprise the IR-FPA and that define boundaries of a currently selected frame of pixels; and subtracting a non-uniformity signal component from the signals read out from the frame. - View Dependent Claims (17, 18)
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Specification