A series of black-body radiation-temperature measurements has been made over the temperature range 1380 K to 3100 K using two different designs of pyrolytic-graphite black bodies with calculated emissivities of 0.999. All measurements were performed at the All-Russian Research Institute for Optophysical Measurements (VNIIOFI) during June 1997. A filter photometer from the VNIIOFI, broadband glass-filter detectors from the Physikalisch-Technische Bundesanstalt (PTB) and narrowband interference-filter-based radiometers from the National Physical Laboratory (NPL) were used to perform the temperature measurements in either radiance or irradiance mode using both black bodies. Across the entire temperature range, the NPL and PTB instruments showed consistent results with both black bodies and differing geometrical arrangements. Results from the VNIIOFI photometer were also broadly consistent for a wide temperature range.

During an international comparison of radiation temperature measurements performed at the AllRussian Institute for Optophysical Measurements (VNIIOFI), Moscow, in June 1997 by participants from the VNIIOFI, the National Physical Laboratory (NPL), Teddington, and the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, detailed measurements of the characteristics of two different types of high-temperature black-body source took place. Both of the black bodies consisted of a pyrolytic-graphite cavity and differed only in the design of the electrodes, which were either axial or coaxial. All investigations were carried out covering a temperature range from 1380 K to 3100 K. The electrical characteristics of the black bodies were investigated at all temperature points; and measurements of the temperature drift were performed to determine the stability of the systems in constant-current mode and in optical-feedback control mode. The uniformity of the black-body radiation field was measured in the radiance mode by using narrowband, interference-filter-based radiometers with imaging optics from the NPL and in the irradiance mode by using broadband-filter detectors from the PTB to scan the irradiated area. The results confirm the suitability of the BB3200 for both radiance and irradiance measurements at national metrological institutes.

The precision blackbody sources developed at the All-Russian Institute for Optical and Physical Measurements (Moscow, Russia) and their characteristics are analyzed. The precision high-temperature graphite blackbody BB22p, large-area high-temperature pyrolytic graphite blackbody BB3200pg, middle-temperature graphite blackbody BB2000, low-temperature blackbody BB300, and gallium fixed-point blackbody BB29gl and their characteristics are described.

The present state of the art of temperature blackbody (HTBB) sources development at the All-Russian Institute for Optical and Physical Measurements (VNIIOFI, Russia) and their characteristics are analysed. The precision graphite blackbody BB22p, operating now at NIST, PTB, NPL and VNIIOFI, large area blackbody BB2000 and super high temperature pyrolitic graphite blackbody BB3200pg are described. Results of their theoretical and experimental investigations are given.