-30 °C to 960 °C to Variable Temperature Blackbody (VTBB) Radiance Temperature Calibration Facility

A blackbody radiance temperature calibration facility (RTCF) has recently been established at the National Institute of Metrology, China, offering calibration and verification services for variable temperature blackbody (VTBB) radiation sources. The RTCF includes reference VTBBs in the range of to and consists of a stirred liquid bath blackbody of to and water, cesium, and sodium heat-pipe blackbodies spanning to . In addition, the facility is equipped with a set of radiation thermometers with different working wavelengths (or wavebands); these thermometers are used to transfer radiance temperatures from the reference to customers' VTBBs. Cavities with V-notch grooves in the inner surface have an estimated emissivity from 0.99986 to 0.99994. The temperature control stability and temperature uniformity of VTBBs are characterized. Furthermore, we test the difference between a cavity and thermometer well temperatures and compare the radiance temperatures of the Cs and Na heat-pipe blackbodies. The expanded uncertainty of VTBBs' radiance temperatures at ( to ) is evaluated from to . The facility has been used to calibrate and characterize customers' VTBBs.