Non-uniformity correction and calibration of a portable infrared scene projector

Abstract

A key attribute of any tester for FLIR systems is a calibrated uniform source. A uniform source ensures that any anomalies in performance are artifacts of the FLIR being tested and not the tester. Achieving a uniform source from a resistor array based portable infrared scene projector requires implementation of nonuniformity correction algorithms instead of controlling the bonding integrity of a source to a cooler, and the coating properties of the source typical of a conventional blackbody. The necessity to perform the non-uniformity correction on the scene projector is because the source is a two-dimensional array comprised of discrete resistive emitters. Ideally, each emitter of the array would have the same resistance and thus produce the same output for a given drive current. However, there are small variations from emitter to emitter over the thousands of emitters that comprise an array. Once a uniform output is achieved then the output must be calibrated for the system to be used as test equipment. Since the radiance emitted from the monolithic array is created by flowing current through micro resistors, a radiometric approach is used to calibrate the differential output of the scene projector over its dynamic range. The focus of this paper is to describe the approach and results of implementing non-uniformity correction and calibration on a portable infrared scene projector.