InSb working standard radiometers

InSb radiometers have been developed and characterized for use as transfer standards at the National Institute of Standards and Technology (NIST). The InSb radiometers will hold a portion of the recently realized infrared spe ctral response scale of the NIST and will serve as working standards for th e calibration of test detectors. These radiometers will measure radiant pow er or irradiance from 2 mu m to 5.4 mu m. They have a 17 degrees field-of-v iew. The InSb detectors were selected for high shunt impedance to achieve h igh sensitivity. The transimpedance-gain, voltage-gain, and loop-gain of th e current-to-voltage converters were optimized for optical radiation choppe d at 40 Hz. At the peak response, the noise-equivalent-power is 0.6 pW in a n electrical bandwidth of 0.3 Hz. The ratio of the de ambient-background cu rrent to the ac noise-equivalent current is 10(7). Spatial and angular resp onsivities, linearity, stability, and flashing were also characterized.