Over the years, a number of international comparisons have been performed, in the field of radiation thermometry, to compare realisation of temperature scales. These have involved the use of a transfer instrument circulated among participants and were designed to compare the different ITS-90 realisations at different national measurement institutes (NMIs). EUROMET project 658 ('The examination of base parameters for ITS-90 scale realisation') was instigated to investigate the uncertainties of some of the underlying parameters in these ITS-90 realisations, namely: the size-of-source effect, linearity and relative spectral response of a radiation thermometer, and the calculation of the emissivity of different designs of blackbody cavity. The comparison was led by NPL and involved the following NMIs: PTB, VSL, CEM, UME, BNM-INM (Cnam) and IMGC. The comparison was performed by circulating two precision radiation thermometers (an IKE LP3 belonging to PTB and a VEGA TSP2 belonging to IMGC). This report describes the measurement procedures used in each laboratory and compares the results obtained from the measurements by the participants.

Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by EUROMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).