Report on EURAMET supplementary comparison on measurement of a 1 mm stage micrometer

The results of the EURAMET supplementary comparison on the calibration of a 1 mm stage micrometer are reported. 13 NMIs from 4 RMOs participated in the comparison. Originally, the comparison was planned to use a single artefact. Because it was destroyed during the duration of the comparison, it was necessary to carry out the test in two loops using a new artefact. Artefact circulation started in August 2020 and was completed in September 2022. Both artefacts were the same make and kind. The two artefacts are standard stage micrometers as used in optical microscopy on a transparent, low thermal expansion substrate. The scale length is 1 mm divided in 100 parts. The distances of all 100 scale marks from the zero mark have been measured by each participant. The results with associated uncertainties of all participating NMIs were in good agreement. All En values were smaller than 1 already from the pre-draft A state on. Therefore, no separate analysis of a largest consistent subset was necessary. With 1400 values without a single outlier, it is tempting to assume that uncertainty contributions are somehow overestimated. 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 https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).