Abstract
Electron storage rings are nearly ideal radiation sources for radiometry over a broad spectral range from the infrared to the x-ray region. Many national metrology institutes make extensive use of synchrotron radiation for radiometry. The Synchrotron Ultraviolet Radiation Facility SURF III, which has recently been upgraded, is used by the National Institute of Standards and Technology (NIST), and the Physikalisch-Technische Bundesanstalt (PTB) operates a European radiometry laboratory at the third-generation storage ring BESSY II. The storage rings are used as calculable broadband radiation sources (primary source standards) and in combination with primary detector standards as sources of continuously tunable monochromatic radiation for detector calibration. The use of cryogenic electrical-substitution radiometers as primary detector standards has made it possible to considerably extend high-accuracy calibrations from the ultraviolet (UV) to the x-ray regime. Radiometry in the extreme UV (EUV) range, and in particular reflectometry, has become increasingly important for the development of EUV lithography. An overview of synchrotron radiation based radiometry will be given.