High performance spectroradiometer for very accurate radiometric calibrations and testing of blackbody sources and EO test equipment

摘要

In the late eighties CI Systems pioneered the radiometric calibration and testing of electro-optical infrared test equipment by using its advanced in-house developed infrared spectroradiometer (the SR 5000), applied to measurements of signatures of military objects and long path atmospheric spectral transmission. Technological advances of frame rates, temperature resolution, spatial resolution, widened spectral ranges and other performance parameters of Forward Looking Infrared imaging systems (FLIR's) and other electro-optical (EO) devices require more advanced test and calibration equipment. The projected infrared radiation of such equipment must be controlled with better radiance resolution and accuracy. CI has carried out a number of optical modifications of the SR 5000, together with especially dedicated calibration algorithms, to significantly improve the blackbody radiance measurements at temperatures close to room temperature, resulting in: ⅰ) a factor of 5 improvement in sensitivity, measured by Noise Equivalent Temperature Difference (NEΔT), and ⅱ) a factor of 5 to 10 improvement in accuracy (in the 3-5 micron and 8-12 microns spectral regions respectively). The most important modifications are the use of a higher D~* and smaller detector, a different detector alignment procedure in which the signal to noise ratio is traded off with field of view uniformity of response, and a calibration procedure based on the division of the blackbody temperature range into several independent sub-ranges. As a result, the new spectroradiometer (the SR 5000WNV) has advanced infrared spectroradiometry so that it now allows the EO device manufacturers to characterize the most modem and future test equipment, and insure its being suitable to test the new advanced infrared imaging systems.