Method and apparatus for calibrating a focal plane array of an image detector
First Claim
1. A method of calibrating a focal plane array of an image detector, comprising:
- detecting a portion of an image at a first detector element of the image detector for a first rotation position of the image relative to the image detector;
detecting the image portion at a second detector element of the image detector for a second rotation position of the image relative to the image detector;
comparing a first output of the first detector element in response to the image portion detected at the first rotation position to a first output of the second detector element in response to the image portion detected at the second rotation position; and
adjusting an offset and gain of the first and/or second detector element in response to the comparing step.
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Accused Products
Abstract
An image detection system (10) includes a derotation optics assembly (24) that stabilizes images viewed from a scene (14) by individual detector elements (31) in a focal plane array (32). The derotation optics assembly (24) also is used in providing scene based calibration to the individual detector elements (31). The derotation optics assembly (24) places images viewed from the scene (14) in a first rotation position. The individual detector elements (31) collect scene based energy at the first rotation position. The derotation optics assembly (24) places images viewed from the scene (14) in a second rotation position. The individual detector elements (31) collect scene based energy at the second rotation position. Comparisons are made among outputs of the individual detector elements (31) at the first and second rotation positions. Correction factors for each of the individual detector elements (31) are adjusted in response to the comparisons in order to compensate for the differing voltage offsets and gains among the individual detector elements (31).
21 Citations
28 Claims
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1. A method of calibrating a focal plane array of an image detector, comprising:
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detecting a portion of an image at a first detector element of the image detector for a first rotation position of the image relative to the image detector; detecting the image portion at a second detector element of the image detector for a second rotation position of the image relative to the image detector; comparing a first output of the first detector element in response to the image portion detected at the first rotation position to a first output of the second detector element in response to the image portion detected at the second rotation position; and adjusting an offset and gain of the first and/or second detector element in response to the comparing step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for calibrating a focal plane array of an image detector, comprising:
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an afocal lens assembly for receiving and collimating scene based energy from a scene; a derotation optics assembly for stabilizing the scene based energy; a converging optics assembly for inverting the scene based energy; and a focal plane array for forming an opto-electronic approximation of the scene based energy, the focal plane array having a plurality of individual detector elements for generating the opto-electronic approximation, the derotation optics assembly placing the scene based energy in a first rotation position for collecting a first grid of the scene based energy at the individual detector elements, the derotation optics placing the scene based energy in a second rotation position for collecting a second grid of the scene based energy at the individual detector elements, the focal plane array comparing the first grid to the second grid for adjusting correction factors of each individual detector element in order to compensate for differing voltage offsets and gains among the plurality of individual detector elements. - View Dependent Claims (13, 14, 15, 16)
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17. A method for calibrating an image detector which has a plurality of detector elements, comprising the steps of:
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directing energy from a scene onto the image detector with a first orientation relative to the image detector; detecting first image information with the image detector when the energy has the first orientation; directing the energy onto the image detector with a second orientation relative to the image detector, the second orientation being different from the first orientation; detecting second image information with the image detector when the energy has the second orientation; comparing information from the first image information to information from the second image information; and adjusting an operational parameter associated with a selected one of the detector elements in response to said comparing step. - View Dependent Claims (18, 19, 20, 21)
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22. An apparatus, comprising:
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a focal plane array which includes an image detector having a plurality of detector elements; and an optical section which can direct energy from a scene onto said image detector with first and second orientations relative to said image detector, the first orientation being different from the second orientation; said focal plane array being operative to detect first image information and second image information with said image detector when the energy respectively has the first orientation and the second orientation, being operative to compare information from the first image information to information from the second image information, and being operative to adjust an operational parameter associated with a selected one of said detector elements in response to a result of the comparison. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification