Calibration of Radiometric Transfer Standards in the UV and VUV by Electron Synchrotron Radiation Using a Normal Incidence Radiometer

Abstract

In order to utilize the electron synchrotron radiation for the calibration of radiometric transfer standards a radiometer has been developed which is in use at the Deutsches Elektronen-Synchrotron (DESY, Hamburg). The radiometer is designed for calibrating transfer standards of the spectral radiance and irradiance for wavelengths between 80 nm and 350 nm. By the method used it is avoided that after calibration with synchrotron radiation the transfer standards have to be converted to an absolute scale by comparing them with a conventional standard in the uv. This is especially vital for those vuv standards which do not emit any measurable radiation in the uv. In this paper the quality of the underlying principle of measurement is stressed by determining the spectral radiance of commercial deuterium lamps (165 nm to 340 nm). The uncertainty of the measured spectral radiance is ±2%. This uncertainty is confirmed by comparative measurements (290 nm to 340 nm) based on the radiation of tungsten tube black-body at a temperature of about 2500 K.