Abstract. At its meeting in March 1997, the Consultative Committee for Photometry and Radiometry (CCPR) identified several key comparisons in the field of optical radiation metrology, one of which concerns spectral responsivity. The present report concerns the key comparison CCPR-K2.b, international comparison of spectral responsivity measurements in the wavelength range 300 nm to 1000 nm, piloted by the BIPM.

The comparison was carried out through the calibration of a group of transfer detectors, single silicon photodiodes and trap detectors, by the 17 participating national metrology institutes. It was organized in a star form, in two phases with two groups of participants.

The report describes in detail the measurements made at the BIPM and summarizes the reports submitted by the participants. A key comparison reference value and degrees of equivalence have been determined from the calibration results.

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 the CCPR, according to the provisions of the Mutual Recognition Arrangement (MRA).