A newly designed comparator was developed for the measurement of both diameter and form of cylinders, spheres and cubes in only a single specimen setting using a contact probe technique. The measurement volume is mm, and the uncertainty aimed at is 0.01 per 100 mm length for calibrations of outer diameters, form and parallelism. The measured values obtained from outer length comparison measurements between three of PTB's standard length comparators and the new comparator agree within nm.

This paper presents results of the dimensional calibration of piston-cylinder assemblies to be used for the joint NMI project “Re-determination of the Boltzmann constant”. Several measurements optimization strategies are described. For the first time 3D uncertainties in the range of 8 nm (piston) and 16 nm (cylinder) could be achieved.

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.