A cryogenic radiometer-based system was constructed at the National Institute of Standards and Technology (NIST) for absolute radiometric measurements to improve detector spectral responsivity scales in the wavelength range from 900 nm to 1800 nm. In addition to the liquid-helium-cooled cryogenic radiometer, the system consists of a 100 W quartz-tungsten-halogen lamp light source and 1 m single-grating monochromator for wavelength selection. The system was characterized and the uncertainty in radiant power responsivity measurements evaluated. A variety of photodetectors, including indium gallium arsenide photodiodes (InGaAs), germanium (Ge) photodiodes, and pyroelectric detectors were subsequently calibrated. Over most of the spectral range, the radiance responsivity of the photodetectors can be measured with a combined relative standard uncertainty of 0.4% or less. This is more than a factor of two less than our previous capabilities, and represents a significant improvement in the near infrared (NIR) spectral responsivity scale maintained at NIST. We discuss the characterization of the monochromator-based system and present results of photodetector spectral response calibrations.
Citation: Journal of Research (NIST JRES) -
Volume: 105 No. 5
NIST Pub Series: Journal of Research (NIST JRES)
Pub Type: NIST Pubs
cryogenic radiometer, detector standards, electrical substitution, IR detector, near infrared, radiometry, responsivity