Portable high accuracy double spectrometer for ultraviolet spectral irradiance measurements

A portable high accuracy double spectrometer for ultraviolet (UV) spectral irradiance measurements has been under development at the National Institute of Standards and Technology (NIST) for several years. It has been used in the comparison of NIST spectral irradiance sources: an electron storage ring, 1000 W quartz-halogen lamps, deuterium are lamps, and a windowless argon miniarc. A. UV spectral irradiance intercomparison with the Physikalische Technische Bundesanstalt (PTB) of Germany has also been carried out with the instrument. This paper will discuss the modular design of this instrument, preliminary uncertainty analysis, results of standard source comparisons and results of solar ultraviolet measurements using the UV spectrometer with the NIST spectral irradiance field calibrator.