Measurement deviations of 3D fibre probes reduced

As part of a research project funded by the Central Innovation Program for SMEs (ZIM) of the BMWK, it was possible to reduce the measurement errors of the tactile-optical 3D micro probe (3D fiber probe) in cooperation with Werth Messtechnik GmbH.

In the currently available 3D fiber probe, the z-deflection of the probing sphere is detected with the aid of a sensor that uses the Foucault measurement principle. This sensor limits the achievable accuracy of the probe, especially because of its strongly non-linear characteristic and the heat input into the coordinate measuring machine caused by the sensor electronics. The project, therefore, evaluated several alternative sensor principles and realized a prototype 3D fiber probe with an interferometric z-sensor. Since the sensor has a fiber-coupled design, the sensor electronics are located outside the coordinate measuring machine, so there is no heat input.

Testing of the sensor has shown that the probing error could be reduced to values < 150 nm.

Figure 1: 3D fiber probe on the coordinate measuring machine. Right: currently available version, left: Prototype with new interferometric z-sensor technology.