State of the arts of the infrared radiation thermometry standards in the middle temperature range at NMIJ

A facility for infrared radiation thermometry in the middle temperature range from 100 /spl deg/C to 500 /spl deg/C is being established by the NMIJ. This calibration facility consists of an infrared radiation thermometer and the fixed point blackbodies of In, Sn, and Zn. An InSb infrared radiation thermometer and a zinc-point blackbody with a large opening of 15mm in diameter are constructed and characterized. The stability of radiation thermometer of 5 mK is achieved after a correction of the output drift due to varying ambient temperature. For the blackbody the stability during the plateau and the repeatability for 8 times plateau measurements over a week are 1 mK and 4.8 mK by a standard deviation, respectively. The size-of-source effect is as good as 0.9960 for 15 mm, 0.9992 for 20 mm, and 1 for above 21 mm in diameter.