Design of calibration system for tactile displacement probes

Displacement probes are currently widely used in different branches of manufacturing industry, either as building blocks of special purpose equipment or as a simple distance measuring instrument as for example in a gauge block calibrator. With the increased demand for more accurate products high resolution measuring probes gained more importance. Information about calibration procedures and equipments are rare in the literature. In the paper first the properties of the published calibration systems with nanometer resolution are discussed. Next the new calibration system having 50 nanometer measuring uncertainty is outlined The probe displacement is generated by a single-axis positioning stage driven by a stepping motor. The tip of the probe rests on the backface of the flat mirror with flatness better than λ/100, acting as the mirror of the plane mirror laser interferometer. Angular sensors are used to capture the angular deviation of the mirror in the different measuring positions. The error of the probe is the difference between the value determined by the probe and the value measured by the laser interferometer. Finally the calibration uncertainty is calculated and results are given to show the systems performance.