Radiance Temperature Comparison between CENAM and PTB from −25 °C to 100 °C

Abstract

Centro Nacional de Metrología (CENAM, Mexico) and Physikalisch-Technische Bundesanstalt (PTB, Germany) provide the dissemination of the International Temperature Scale of 1990 (ITS-90) in their respective countries. Presently, CENAM has a declared calibration and measurement capability of radiance temperature from 50 °C to 400 °C for wideband radiation thermometers, and it has been working to extend its services in the low temperature range below 0 °C. The calibration and measurement capability of radiance temperature from −60 °C to 3000 °C is well established at PTB. For this radiance temperature comparison, a high-grade transfer radiation thermometer was used. It was calibrated at PTB against a water heat pipe blackbody and an ammonia heat pipe blackbody. The temperature of each blackbody was measured with a standard platinum reference thermometer (SPRT), so the radiance temperature measurements were traceable to the ITS-90. The radiation thermometer was calibrated at CENAM against a gallium fixed-point blackbody and a variable temperature bath blackbody whose temperature was measured with a calibrated SPRT. The description of the experimental setups used and the measurement results in the −25 °C to 100 °C temperature range are presented. The radiance temperature results obtained at CENAM and at PTB show a good agreement within the estimated uncertainty budget.