<title>Uncertainty of gauge block calibration by mechanical comparison: a worked example for gauge blocks of dissimilar materials</title>

Abstract

The definition of gauge block length, and the lowest-uncertainty gauge block calibrations, derive their link to the definition of the metre through the technique of optical interferometry using calibrated optical wavelengths. Following interferometric calibration of gauge blocks, the technique of mechanical comparison of gauge blocks is largely used for the dissemination of the metre. A measurement scenario for the case of low-uncertainty gauge block calibration in which the working standard and client gauge blocks are made of dissimilar materials is described. The correction for stylus deformation is determined experimentally. A detailed tutorial on evaluating the uncertainties for this gauge block calibration in accordance with the ISO Guide to the expression of uncertainty in measurement is reported, including discussion of degrees of freedom and correlations.

Measurement science and the linking of CIPM and regional key comparisons

“…Three labs participated in both comparisons: CENAM, NIST and NRC, and their results will be used for linking. Relative to the hypothesis of the ideal agreement of the participants, chi-squared testing can examine the statistical consistency of the measurements and the reported uncertainties used for linking [16][17][18][19]. Statistical consistency can be probed for each of the CIPM and RMO data sets independently using conventional chi-squared techniques: the reported measurements and uncertainties are compared against the inverse-variance weighted mean of the measurand as a specific reference value (RV) [2].…”

Uncertainty of Mechanical Calibration of Gauge Blocks of Dissimilar Materials

“…The difference deserves attentive analysis. Canadian national laboratory also states in (Decker et al, 1998) that they measured 40 nm when analytical result was 90 nm, thus 50 nm difference. Similarly, the comparator manufacturer states correction of 50 nm (Tab.…”

Calibration of dial indicators using machine vision

“…The principle of the calculation of uncertainty of measurement is described in [1] and a complete worked example for gauge blocks is described in [5]. The error sources should be evaluated from measurements, experiment, data sheets or experience.…”