In the quest for a better measurement quality, a reduction of the measurement uncertainty must be foreseen. Gauge block calibration by interferometry is an unavoidable link in the traceability chain of most dimensional measurements and it has an impact in the uncertainty budget of all measurements that derive from it. Length-dependent effects of this calibration contribute largely to the combined uncertainty and therefore, its reduction must be expected to improve the combined uncertainty of gauge block calibration by interferometry. The thermal expansivity expressed as a linear thermal expansion coefficient (LTEC) is one of the main sources of uncertainty in the uncertainty budget. The gauge block manufacturer commonly quotes this number with an uncertainty of about one part in 10^-6 degrees C^-1. A reduction of the LTEC uncertainty to one third of the quoted value would provide a decease of at least 25 percent in the combined uncertainty of gauge blocks longer than 50 mm calibrated by interferometry.

Date Published: 22 October 2001
PDF: 10 pages
Proc. SPIE 4401, Recent Developments in Traceable Dimensional Measurements, (22 October 2001); doi: 10.1117/12.445640

Published in SPIE Proceedings Vol. 4401:
Recent Developments in Traceable Dimensional Measurements
Jennifer E. Decker; Nicholas Brown, Editor(s)