Semi-opaque chopper for thermal imaging system and method
First Claim
Patent Images
1. A thermal imaging chopper, comprising:
- at least one open window and at least one covered window;
the covered window formed in part bv a thermally transmissive material, operable to scatter radiant thermal energy from a scene; and
the thermally transmissive material having at least one edge which defines in part the open window;
wherein the transmissive material is manufactured from a polymer.
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Abstract
Thermal imaging chopper (22) having a frame (42) with an open window (47) and a covered window (48). The covered window (48) is preferably covered with a material that partially blocks a selected amount of thermal radiation from a scene and randomly scatters the remaining thermal radiation from the scene that is transmitted through the covered window. The open window (47) allows unrestricted transmission of thermal radiation from the scene.
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Citations
17 Claims
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1. A thermal imaging chopper, comprising:
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at least one open window and at least one covered window; the covered window formed in part bv a thermally transmissive material, operable to scatter radiant thermal energy from a scene; and the thermally transmissive material having at least one edge which defines in part the open window; wherein the transmissive material is manufactured from a polymer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A thermal imaging chopper, comprising:
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at least one open window and at least one covered window; the covered window formed in part by a thermally transmissive material, operable to scatter radiant thermal energy from a scene; and the thermally transmissive material having at least one edge which defines in part the open window; wherein the transmissive material is manufactured from polyethylene.
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10. A thermal imaging chopper, comprising:
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a frame; an opening within the frame which does not restrict the transmission of thermal energy; a covered window disposed within the opening; and a thermally transparent material connected to the frame to define the covered window, to partially block radiant thermal energy and to randomly scatter the radiant thermal energy not blocked; wherein the thermally transparent material is manufactured from polyethylene. - View Dependent Claims (11, 12, 13)
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14. A method of forming a thermal imaging system having a focal plane array with a plurality of thermal sensors to produce an image of a scene in response to incident thermal radiation from the scene and for normalizing the thermal sensor, comprising the steps of:
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focusing a beam of radiant thermal energy from a scene onto the focal plane array; placing a thermal imaging chopper having a frame within the beam of radiant thermal energy before the beam contacts the focal plane array; forming an open window that does not restrict the beam of radiant thermal energy within the frame; forming a closed window within the frame covered by a thermally transparent material that partially blocks the beam of radiant thermal energy and randomly scatters the radiant thermal energy not blocked by the material; rotating the frame at a selected speed to allow the beam of radiant thermal energy to contact the focal plane array without interruption through the open window to provide a signal corresponding to the scene; rotating the frame at the selected speed to allow the closed window to scatter the beams of radiant thermal energy to provide a generally uniform level of thermal energy contacting the thermal sensor to provide a normalized background signal for comparison with the uninterrupted signal from the scene; and forming the covered window from a polymer material that operates to randomly scatter and partially block radiant thermal energy from the scene. - View Dependent Claims (15, 16)
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17. A method of forming a thermal imaging system having a focal plane array with a plurality of thermal sensors to produce an image of a scene in response to incident thermal radiation from the scene and for normalizing the thermal sensor, comprising the steps of:
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focusing a beam of radiant thermal energy from a scene onto the focal plane array; placing a thermal imaging chopper having a frame within the beam of radiant thermal energy before the beam contacts the focal plane array; forming an open window that does not restrict the beam of radiant thermal energy within the frame; forming a closed window within the frame covered by a thermally transparent material that partially blocks the beam of radiant thermal energy and randomly scatters the radiant thermal energy not blocked by the material; rotating the frame at a selected speed to allow the beam of radiant thermal energy to contact the focal plane array without interruption through the open window to provide a signal corresponding to the scene; rotating the frame at the selected speed to allow the closed window to scatter the beams of radiant thermal energy to provide a generally uniform level of thermal energy contacting the thermal sensor to provide a normalized background signal for comparison with the uninterrupted signal from the scene; providing optics for focusing incident thermal radiation emitted by the scene onto the focal plane array; mounting the focal plane array including the plurality of thermal sensors on a substrate with electronic circuits for receiving and processing electrical signal from the thermal sensors to obtain a video signal representing differences in radiance of thermal energy emitted by objects in the scene; and displaying the video signal and displaying an image generated in response to the video signal.
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Specification