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Proceedings Paper

Calibration method for IR channel of dual-band long-range airborne camera
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Paper Abstract

A dual band camera for long-range airborne reconnaissance has a large common Cassegrain objective, a beam splitter, VNIR and MWIR channels. Non-uniformity correction (NUC) must be especially accurate in this type of application, due to the low dynamic range of a raw image acquired through tens of kilometers of atmosphere. Accurate calibration of non-uniformity in the MWIR band represents a challenge, because of considerable emissivity of the optics, variable optics temperature, high cos4 effect, vignetting, complex focal plane geometry, residual misalignment between the exit pupil and the dewar's cold stop, and insertion of a blackbody temperature reference source (TRS) directly in front of the dewar window. The paper describes a special calibration method which overcomes the complexities and achieves high NUC accuracy. The method combines in-laboratory transmissibility measurement with two-stage in-flight periodic calibration. The detector non-uniformity is calibrated in wide signal range. The TRS temperature follows a curve giving linear rise of radiance in time. Inner surface of the pod between the optical windows is used as a uniform source for evaluation of a pattern caused by the optics radiation. This method was successfully implemented in the ElOP long-range oblique photography (LOROP) camera.

Paper Details

Date Published: 30 August 2004
PDF: 9 pages
Proc. SPIE 5406, Infrared Technology and Applications XXX, (30 August 2004); doi: 10.1117/12.544649
Show Author Affiliations
Vladimir Petrushevsky, ElOp Electrooptics Industries Ltd. (Israel)

Published in SPIE Proceedings Vol. 5406:
Infrared Technology and Applications XXX
Bjorn F. Andresen; Gabor F. Fulop, Editor(s)

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