Abstract
This report details the final results of the CCPR comparison on regular spectral transmittance carried out between 2010 and 2016. Scales held by 12 participating national metrology institutes were compared over the spectral range from 380 nm to 1000 nm and over the nominal transmittance range from 0.1% transmittance to 90% transmittance. Sets of five absorbing neutral density filters (nominal transmittance 0.1%, 1%, 10%, 50% and 90%) were measured firstly by the pilot (MSL) and then were sent out in a 'star' format, one to each other participant (A*STAR, KRISS, LNE-CNAM, MKEH, NIST, NMIJ, NMISA, NPL, NRC, PTB, VNIIOFI). This cycle was repeated twice and followed by a final measurement at the pilot. The stability of the filters allowed unilateral degrees of equivalence to be calculated for each participant. These showed that the scales held by the participants are broadly equivalent. The results indicate scope for some participants to improve their measurement claims. Where occasional non-equivalence was revealed, some revision of uncertainty budgets may also be required.
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 CIPM Mutual Recognition Arrangement (CIPM MRA).