Investigation of high-temperature black body BB3200

During an international comparison of radiation temperature measurements pe rformed at the All-Russian Institute for Optophysical Measurements (VNIIOFI ), Moscow, in June 1997 by participants from the VNIIOFI, the National Phys ical Laboratory (NPL), Teddington, and the Physikalisch-Technische Bundesan stalt (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 o nly in the design of the electrodes, which were either axial or coaxial. Al l investigations were carried out covering a temperature range from 1380 K to 3100 K. The electrical characteristics of the black bodies were investig ated at all temperature points; and measurements of the temperature drift w ere performed to determine the stability of the systems in constant-current mode and in optical-feedback control mode. The uniformity of the black-bod y radiation field was measured in the radiance mode by using narrowband, in terference-filter-based radiometers with imaging optics from the NPL and in the irradiance mode by using broadband-filter detectors from the PTB to sc an the irradiated area. The results confirm the suitability of the BB3200 f or both radiance and irradiance measurements at national metrological insti tutes.