First results of a pseudo-Abbe comparator for precision length and diameter measurements

Abstract

High-precision length and form measurements at the top of the traceability chain are mandatory to support industrial metrology with form and length embodiments which are calibrated with the lowest possible measurement uncertainties. Therefore, Physikalisch-Technische Bundesanstalt has replaced an old reference comparator by a new reference measurement system to ensure that this service can be provided safely in the future. The design of the system follows the principle of a pseudo-Abbe comparator. First, measurement results are presented, which indicate the capability of measurement uncertainties in the range of U (k = 2) = 20 nm for length and diameter measurements. The new system can measure length and form in a single clamping, which is a benefit, e.g. for piston-cylinder assemblies calibrations. This paper presents first measurement results on a gauge block and an evaluation of certain parts of the comparator.