Experimental uncertainty evaluation by measuring a micro gear standard using focus variation

Micro gears play an increasingly important role in various industrial applications, and the
minimization of their deviations is challenging for metrology and manufacturing. A promising
method is the focus variation technology, which enables areal measurements of micro gears.
Practice-related standards are used to determine measurement uncertainties by comparison with
calibration values. In this work, the external micro gear standard of the
Physikalisch–Technische Bundesanstalt is used to evaluate experimental measurement
uncertainties of a focus variation coordinate measurement system for the first time. The
traceable standard with modules between 0.1 and 1 mm is calibrated using micro tactile
coordinate measurements. Optical and tactile measurements are then compared. As a result,
small expanded measurement uncertainties of less than 4 μm are achieved.