Radiometric calibration device and method

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.

Dependencies are inferred from the claim text.