Time and Frequency Division

We have constructed a new ultrav iolet (U V) radiom etry facility at the Synchrotron Ultraviolet Radiation Facility (SURF II) at the National Institute of Standards and Technology (N IST). The facility combines a high-throu ghput norm al-in cidence monochrom ator with an absolute cryogenic radiom eter (A CR) optim ized for UV m easurem ents to provide absolute detector-based radiom etric calibratio ns in the spectral range 125 nm to approxim ately 320 nm. The system can be con® gured for spectro radiom etric calibration of photodetectors with completely automated m apping of detecto r spatial and angular responsivity . The facility can easily be adapted for other spectro radiom etric measurem ents includ ing tran smittan ce and re¯ectance and the spectral range can be extended to about 50 nm.

We have constructe d a new ultraviolet (U V) radiometry facility at the Synchrotron Ultraviolet Radiation Facility (SURF II) at the National Institute of Standards and Technology (N IST). The facility combines a high-throughput normal-incidence monochromator with an absolute cryogenic radiometer (A CR) optimized for UV m easurem ents to provide absolute detector-based radiometric calibrations in the spectral range 125 nm to approximately 320 nm. The system can be con® gured for spectroradiom etric calibration of photodetectors with completely automated m apping of detector spatial and angular responsivity. The facility can easily be adapted for other spectroradiom etric measurements including transmittance and re¯ectance and the spectral range can be extended to about 50 nm.