THERMAL DETECTION SYSTEM HAVING A RAPID-RESPONSE CALIBRATION DEVICE

摘要

PCT No. PCT/GB96/01805 Sec. 371 Date Jan. 9, 1998 Sec. 102(e) Date Jan. 9, 1998 PCT Filed Jul. 29, 1996 PCT Pub. No. WO97/05742 PCT Pub. Date Feb. 13, 1997A thermal sensing system (10) including an array of photon detectors (14) produces a detector-dependent response to irradiation. Variations in individual detector characteristics produce a fixed pattern noise which degrades an image or other response. A switchable mirror (M1) may at one position (Pcal) direct infrared radiation from a light emitting diode (20) onto the detector array (14). The diode (20) is both a negative and positive luminescent emitter, the flux emitted is current controlled to be equivalent to black body radiation at a range of temperatures both colder and hotter than ambient. Calibration relationships comprising transfer functions relating incident intensity to signal response are derived for each detector. Alternatively the mirror (M1) may be at an observation position (Pobs) and infrared radiation from a remote scene reaches the detector array (14). Resulting detector signals are converted into corrected fluxes using individual calibration relationships previously derived and an image or response with reduced fixed pattern noise is obtained.