IMPROVEMENTS IN OR RELATING TO THE CALIBRATION OF INFRA RED CAMERAS

摘要

Described herein is an improved reference surface 10 which can be used for calibrating cooled infra red detectors. The reference surface 10 comprises a plurality of corner cube units 12, 14, 16, 18, 20, 22 which reflect radiation directly incident on them. The surface of each corner cube unit 12, 14, 16, 18, 20, 22 is partially reflective and partially emissive so that, when imaged by a cryogenically cooled detector, the reference surface 10 appears as a black body source at a lower temperature than the actual temperature thereof.