Radiation Thermometry of Blackbodies

Two aspects of radiation thermometry of blackbodies (with traceability to the ITS-90 and within framework of relative primary radiometric thermometry, with traceability to the kelvin, the base unit of the SI) are considered. The design features and common sources of systematic errors of narrowband radiation thermometers suitable for measuring blackbody temperatures above the freezing point of silver are discussed. Techniques of temperature extrapolation, interpolation, and least squares fitting based on the Planck and Sakuma-Hattori equations, as well as the methods for evaluating the measurement uncertainties are described. Finally, application of the radiation thermometry to the measurement of temperature nonuniformities over blackbody radiating surfaces is outlined.