Radiometric calibration device and method
First Claim
1. Apparatus for radiometrically calibrating an imaging sensor array using the sun as a calibration light source in an optical system of the type having an accessible real conjugate of an entrance pupil, comprising:
- a) a flux concentrator for concentrating sunlight;
b) a flux modulator for modulating the intensity of the concentrated sunlight;
c) a flux relay for relaying the intensity modulated sunlight to the real conjugate of the entrance pupil of the optical system; and
d) a flux diffuser located at the real conjugate of the entrance pupil of the optical system for illuminating the imaging sensor array with diffuse intensity modulated sunlight.
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Abstract
Apparatus and method for radiometrically calibrating an imaging sensor array using the sun as a calibration light source in an optical system of the type having an accessible real conjugate of the entrance pupil, includes a flux concentrator for concentrating the sunlight. A flux modulator modulates the intensity of the concentrated sunlight and a flux relay for relaying the intensity modulated sunlight to the real conjugate of the entrance pupil of the optical system. A flux diffuser located at the real conjugate of the entrance pupil of the optical system illuminates the imaging sensor array with diffuse intensity modulated sunlight for calibrating the imaging sensor. A radiometric calibration assembly is proposed to calibrate an imaging sensor array of an earth imaging system. The calibration assembly comprises a flux concentrator, a flux modulator, a flux relay lens and a flux diffuser located within a conjugate pupil of the earth imaging system. The flux concentrator transfers solar flux to the flux modulator, which modulates the flux to a number of controlled, deterministic levels. The flux relay lens transfers the modulated flux to the flux diffuser. The diffused flux illuminates the imaging sensor array, resulting in electrical signals that provide information to allow accurate calibration for use in imagery.
43 Citations
40 Claims
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1. Apparatus for radiometrically calibrating an imaging sensor array using the sun as a calibration light source in an optical system of the type having an accessible real conjugate of an entrance pupil, comprising:
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a) a flux concentrator for concentrating sunlight; b) a flux modulator for modulating the intensity of the concentrated sunlight; c) a flux relay for relaying the intensity modulated sunlight to the real conjugate of the entrance pupil of the optical system; and d) a flux diffuser located at the real conjugate of the entrance pupil of the optical system for illuminating the imaging sensor array with diffuse intensity modulated sunlight. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for radiometrically calibrating an imaging sensor array using the sun as a calibration light source in an optical system of the type having an accessible real conjugate of an entrance pupil, comprising the steps of:
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a) concentrating sunlight with a solar flux concentrator; b) modulating the intensity of the concentrated sunlight with a flux modulator; c) relaying the intensity modulated sunlight with a flux relay to the real conjugate of the entrance pupil of the optical system; d) diffusing the concentrated, modulated sunlight with a flux diffuser at the real conjugate of the entrance pupil of the optical system; and e) illuminating the imaging sensor array with the diffuse intensity modulated sunlight. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification