Satellite attitude sensor using thermal imaging
First Claim
1. A method for distinguishing a boundary of a celestial object from background of space using a sensor mounted on a satellite, comprising:
- a) focusing electromagnetic radiation from at least one field of view of about 10 degrees, said field of view substantially spanning at least a portion of a boundary of an object and background adjacent to said at least a portion of said boundary as an image onto a detection means, the detection means including a microbolometer having an elongate array of microbolometer elements capable of providing spatial sampling of an image focussed thereon; and
b) determining a boundary of an object from its background from a spatial transition in intensity of an image focussed on said detection means.
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Accused Products
Abstract
The present invention provides a method for distinguishing a boundary of an object, and the object itself, from its background. In the method electromagnetic radiation is detected from at least one field of view substantially spanning the boundary of the object and background adjacent to the boundary and superimposed or overlaid as images onto a detector. The method includes correlating spatial transitions in intensity of the overlaid images on the detector with a boundary of the object. When used for determining the attitude of a satellite with respect to the earth, the detector is a thermal infrared detector thereby providing a sharp contrast between the thermal emission of the earth and cold space. The invention provides a simple, effective method and device for determining satellite orientation and/or attitude with respect to a thermal infrared-emitting target body. The sensor includes a segmented limb-looking mirror to provide multiple fields-of-view within the field-of-regard and superimposing these fields-of-view as images onto a common detector. The required resolution can be obtained while providing a wide range of operational orbital altitudes. The attitude of the satellite can vary by a large angle from the minimal orientation while still permitting an accurate determination of attitude. Multiple channels in a modular form provide redundancy, improved accuracy, and the opportunity of providing more diverse configurations. The utilization of uncooled microbolometer arrays as imaging detectors removes the requirement for additional cooling equipment thereby providing a low cost, small size and low mass sensor with configurational flexibility and no moving parts.
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Citations
39 Claims
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1. A method for distinguishing a boundary of a celestial object from background of space using a sensor mounted on a satellite, comprising:
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a) focusing electromagnetic radiation from at least one field of view of about 10 degrees, said field of view substantially spanning at least a portion of a boundary of an object and background adjacent to said at least a portion of said boundary as an image onto a detection means, the detection means including a microbolometer having an elongate array of microbolometer elements capable of providing spatial sampling of an image focussed thereon; and b) determining a boundary of an object from its background from a spatial transition in intensity of an image focussed on said detection means. - View Dependent Claims (2, 3, 4, 38)
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5. A device for distinguishing a boundary of an object from its background, comprising:
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a housing; detection means mounted in said housing for detecting electromagnetic radiation, said detection means including a microbotometer having an elongate array of microbolometer elements for spatial sampling of images focused thereon; optical focusing means mounted in said housing for focusing electromagnetic radiation from at least one field of view as an image onto said detection means; and processing means connected to said detection means for correlating a spatial transition in intensity of an image focused on said detection means with a boundary of an object, wherein said processing means includes a semiconductor chip integrated with said detection means for processing of the output of the detection means. - View Dependent Claims (6, 7, 8, 9)
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10. A device for determining satellite orientation and attitude with respect to a celestial body, comprising:
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an effective number of optical modules adapted to be attached to a satellite in preselected positions with respect to each other, each optical module including a detection means adapted to spatially sample an image focused thereon, a segmented mirror having at least one mirror segment, and focusing mirror means located with respect to said segmented mirror for receiving images reflected from said at least one mirror segment and focussing said image onto said detection means; and processing means connected to said detection means, said processing means adapted to correlate spatial transitions in intensity of said image focused on said detection means with a boundary of the celestial body and determining therefrom satellite attitude with respect to the celestial body. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 39)
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24. A device for determining orientation and attitude of a satellite with respect to a celestial body, comprising:
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an effective number of modules adapted to be attached to a satellite in preselected positions with respect to each other, each optical module including pixelated detection means, optical focusing means mounted in each module for collecting and focusing electromagnetic radiation from at least one field of view onto said pixelated detection means, said optical focusing means including a segmented mirror having n mirror segments each disposed at preselected angles with respect to one another, wherein n is an integer greater than or equal to 2, and a focusing mirror means for superimposing images from each of said mirror segments onto said pixelated detection means; and processing means connected to said pixelated detection means for correlating a spatial transition in intensity of said image with a boundary of said celestial object and determining therefrom satellite attitude and/or orientation with respect to the celestial body. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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32. A satellite having a satellite structure and an equipment complement, comprising:
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an orientation and attitude sensor for determining satellite orientation and attitude of said satellite with respect to a celestial body, said sensor including; an effective number of optical modules adapted to be attached to said satellite structure in preselected positions with respect to each other, each optical module including pixelated detection means, optical focusing means mounted in said module for collecting and focusing electromagnetic radiation from at least one field of view as an image onto said pixelated detection means, said optical focusing means including a segmented mirror having n mirror segments each disposed at preselected angles with respect to one another, wherein n is an integer greater than or equal to 2, and a focusing mirror means for superimposing images from each of said mirror segments onto said pixelated detection means; and processing means connected to said pixelated detection means for correlating a spatial transition in intensity of said image with a boundary of said celestial object and determining therefrom satellite attitude and/or orientation with respect to the celestial body. - View Dependent Claims (33, 34, 35)
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36. A satellite sensor device for detecting fires on the earth, comprising:
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a sensor housing; a pixelated infrared detector mounted in said housing for detecting infrared electromagnetic radiation characteristic of fires; optical focusing means mounted in said sensor housing for superimposing images from at least two fields of view of the earth'"'"'s surface as overlaid images onto said infrared detector; and means for correlating a spatial transition in intensity of said overlaid images on said infrared detector with a boundary of a region emitting infrared radiation characteristic of fires. - View Dependent Claims (37)
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Specification