In 2004, the National Institute of Standards and Technology (NIST) established the ultraviolet (UV) spectral irradiance scale from 200 nm to 400 nm using the calculable irradiance of the Synchrotron Ultraviolet Radiation Facility (SURF). Since the establishment of the scale, spectral irradiance calibrations of many customer lamps have been performed in direct comparison to synchrotron radiation. However, to ensure long-term stability of the scale, three check-standard deuterium lamps were calibrated using SURF III at the same time the customer lamps were being calibrated. Here, we present the results of the long-time monitoring of the scale using these check-standard lamps to verify that the customer lamps are calibrated within the total expanded calibration uncertainty of 1.2 % (k=2).
Deuterium Lamp, Irradiance Scale, Spectral Irradiance, Synchrotron Radiation, Ultraviolet Radiometry, Ultraviolet