INFRARED PROJECTOR EFFECTIVE BLACKBODY TEMPERATURE

The effective blackbody temperature used to specify the radiant output from an IR projector is defined formally as the temperature assumed b y the blackbody target that generates the same signal radiance as the IR projector characterized. Analytical expressions and graphical analy ses are developed enabling the calculation of the black-body temperatu re in terms of both the actual device temperature and a specified acti ve zone attenuation coefficient, the latter quantifying the deviation from blackbody behavior. Both the projector signal radiance and the si gnal current developed in the imaging unit under test illuminated by t he projector are shown to be readily calculable once the value of the effective blackbody temperature is known. The analysis is applied to t he comparison of the thin film resistor, silicon bridge resistor, and suspended membrane resistor emissive IR projection technologies.