Supercontinuum-Source-Based Facility for Absolute Calibration of Radiation Thermometers

At the National Metrology Institute of Japan (NMIJ), a new monochromator-based absolute radiometric calibration system for radiation thermometers has been developed with a supercontinuum (SC) source instead of a tungsten-halogen lamp. Compared with halogen lamps, remarkably higher spectral radiance can be obtained from the SC-monochromator-based system because the SC optical radiation can be efficiently coupled into the narrow entrance slit of the monochromator, thus enabling coupling of the monochromatic light from the exit slit into an integrating sphere, which serves as a wavelength-tunable source for calibrating radiation thermometers against a reference detector. In this work, the setup and preliminary measurement results of the SC-source-based system at the NMIJ are described. Techniques for power stabilization, wavelength determination, spatial-uniformity improvement, and interference fringe reduction are applied to the system. The uncertainties of the facility for thermodynamic temperature measurements are estimated.