Uncertainty of Radiant Power Calibration based on Synchrotron Radiation caused by Spectral Distribution and Polarization State

Abstract

We have been attempting to establish an absolute scale of spectral radiance in ultraviolet and vacuum ultraviolet regions by using synchrotron radiation as a primary standard light source and also attempting to transfer the absolute scale to an under‐test light source by comparing the under‐test source with synchrotron radiation. The calibration apparatus does not function as ideal comparator because some properties of incident radiation, which are spectral distribution and polarization state, are different between synchrotron radiation and the under‐test light source, and the signal of the apparatus accordingly depends on not only spectral radiant power but also depends on the properties of the incident radiation. We evaluated how the detector signal ratio was affected by the difference both experimentally and theoretically, and also evaluated the uncertainty of the scale transfer caused by the difference.