George P. Eppeldauer, Alan L. Migdall, Leonard M. Hanssen
Standard quality InSb radiometers have been developed and characterized at the national Institute of Standards and Technology (NIST). The InSb radiometers will hold the recently realized spectral response scale of the NIST and will serve as working standards for the calibration of test detectors. These radiometers will measure radiant power of irradiance from 2 um to 5.4 um. They have a 17 field-of-view. The InSb detectors were selected for high shunt impedance to achieve high sensitivity. The transimpedance-gain, the voltage-gain, and loop-gain of the current-to-voltage converters were optimized for optical radiation chopped at 40 Hz. At the peak response, the noise-equivalent-power is 0.6 pW in an electrical banwidth of 0.3 Hz. The ratio of the dc ambient-background current to the ac noise-equivalent current was 107. Spatial and angular responsivities, linearity, stability, and flashing were also characterized.