| Abstract | Gauge blocks are one of the main artifacts used to calibrate length measuring instruments. The highest grade gauge blocks are calibrated by interferometry making them traceable to the length unit, the metre. The transfer of the wavelength of light to these artifacts is a challenging calibration that requires state-of-the-art equipment, good control of ambient conditions and knowledgeable personnel. It is one of the main calibration services offered by National Metrology Institutes. The Consultative Committee for Length (CCL) has established key comparisons as a means for assuring world-wide traceability and equivalence of length measurements at the highest levels of accuracy. In the key comparison reported here, there were twelve participants from EURAMET, COOMET, AFRIMET, APMP, and SIM regions. This comparison was based on the circulation of seven short steel gauge blocks, six short ceramic gauge blocks, and three steel long gauge blocks. The exercise was successful, and the results of the participants are reported here. |
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