Asia/Pacific metrology programme gauge block comparison - 1993/94

Abstract

A comparison of gauge blocks has been carried out in the Asia/Pacific Region as part of an international comparison decided on by the Comite Consultatif pour la Definition du Metre. Ten national standards laboratories measured a set of five grade 00 gauge blocks (and two replacements) using interferometry. This paper reports on the comparison and shows that for gauge block lengths up to 40 mm (original set) all laboratories agreed to within +/- 0,03 mu m and for the 100 mm gauge block they agreed to within +/- 0,08 mu m. For most of the participants this was the first international comparison involving gauge block interferometry and the results revealed that the participating laboratories were performing well. A comparison like this puts a lot of pressure on all the participants to make the best measurements and to carry them out in the shortest possible time. Measurements of the deviation from nominal length were within +/- 0,03 mu m for lengths up to and including the 40 mm block (with one unusual reading on the replacement 40 mm block). This is half the ISO 3650 tolerance on nominal length for blocks up to 10 mm and about one third of the tolerance for a 40 mm block (+/- 0,10 mu m). Measurements on the 100 mm block were all within +/- 0,08 mu m which is about half the ISO 3650 tolerance for this block length (+/- 0,14 mu m).