Monochromator-based cryogenic radiometry at the NRC

A facility is being set up at the National Research Council of Canada for the monochromator-based spectral calibration of transfer standard radiometers using a cryogenic absolute radiometer. General design features and target performance of the new apparatus are discussed. The sources of error inherent to detector calibrations performed using monochromator-based sources are analysed in some detail, with special attention devoted to bandwidth errors, polarization effects and the effect of the angular subtense of the beam. Some detector effects, such as spatial uniformity and temperature dependence, are also discussed. A status report is given on the development of the new cryogenic radiometer facility.