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

Vladimir Petrushevsky

doi:10.1117/12.544649

30 August 2004 Calibration method for IR channel of dual-band long-range airborne camera

Vladimir Petrushevsky

Proceedings Volume 5406, Infrared Technology and Applications XXX; (2004) https://doi.org/10.1117/12.544649
Event: Defense and Security, 2004, Orlando, Florida, United States

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.

Citation Download Citation

Vladimir Petrushevsky "Calibration method for IR channel of dual-band long-range airborne camera", Proc. SPIE 5406, Infrared Technology and Applications XXX, (30 August 2004); https://doi.org/10.1117/12.544649

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