Ultraviolet calibration of detectors with respect to a cryogenic radiometer

A facility has been designed to perform a variety of detector characterizations in the air-ultraviolet in the spectral range 230 nm to 400 nm. The facility allows the measurement of spatial uniformity, linearity and the spectral responsivity of different detectors, irradiated by a He-Cd laser or by a monochromator and Xe discharge lamp. With this technique, a set of Si photodiodes, Si detectors in trap configuration, and ultraviolet (UV) radiometers built with SiC detectors in an integrating sphere, have been calibrated and their absolute responsivity at the He-Cd laser UV line has been determined with respect to an absolute cryogenic radiometer.