Triple-Fixed-Point Blackbody for the Calibration of Radiation Thermometers

A new triple-fixed-point blackbody containing the fixed-point materials aluminum (freezing point 660.323◦C), zinc (FP 419.527◦C), and tin (FP 231.928◦C) in one device has been developed at the Ilmenau University of Technology. It enables calibration of a radiation thermometer with direct reference to the ITS-90 at three fixed points after a single adjustment of the calibration object. The setup significantly reduces the technical effort and the time for the calibration procedure. Measurements of the phase-transition temperature and the time-dependent blackbody temperature made with a transfer radiation thermometer, the Linearpyrometer LP5 of the IKE Stuttgart, are preseInted in the article.