Measurement of a 1 mm Stage Micrometer
Project Description
The comparison has been proposed and is organised by BEV (AT). The comparison is complementary to concurrent comparison EURAMET.L-K7.2020, in order to serve the needs of National Metrology Institutes using different techniques and/or lower uncertainties for stage micrometers. The artefact will be a single stage micrometer of 1 mm total length. The participants are asked to report all 100 divisions in electronic format.
The technical protocol can be downloaded here>>.
Final Report 2024-06-18
13 NMIs from 4 RMOs participated in the comparison. Originally, the comparison was planned to use a single artefact. Because this artefact 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 of 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. No separate analysis of a largest consistent subset was necessary therefore. With 1400 values without a single outlier, it is tempting to assume that uncertainty contributions are somehow overestimated.
Progress Report 2023-10-03
The circulation was completed in September 2022 and the artefact was inspected by the pilot. All reported results are fairly consistent with no significant outlier or other problems. The Draft A report (Excel sheet with results and preliminary evaluation) was sent to participants end of 2022 with no objections. The pilot planned to issue the final report in a machine-readable form. After some time-consuming study on the status of international standardisation and available software tools, it was decided to put this project last.
So, the Draft B report will be issued in the standard CCL format in due time.
Progress Report 2022-02-16
The measurements started in August 2020 with BEV (AT), GUM (PL), INM (RO), CEM (ES), RISE (SE), INRIM (IT) in this order. CEM reported severe contamination of the artefact on reception. This was confirmed by an intermediate inspection at BEV. The artefact was actually unusable and was sent to PTB (DE, not a participant in this comparison) for further investigations.
It was decided to use the first three reported results before contamination (BEV, GUM, INM) and to start over with a new acquired and characterised artefact. CEM, RISE and INRIM withdraw the results on the first (destructed) artefact and will perform measurements with the new stage micrometer. This new round started at March 2021 with following participants: DMDM (RS), NIM (CN), NMISA (ZA), INMETRO (BR), INTI (AR). This sequence is concluded and all but one participant reported results so far. (NMISA was not able to perform the measurements due to problems with their lab.)
The arrangements for regulations of the customs (carnet ATA) did not work satisfactory in all countries. A massive delay at the importing to the EU was the consequence.
Finally, the timetable was updated, and the measurements are on schedule now. Following NMIs will complete the circulation CEM (ES), INRIM (IT), RISE (SE), UME (TR) and NMISA (ZA).