The shape deviations of the stylus of touch probes significantly affect the measurement uncertainty of the tactile touching topography measurement. In order to reduce its influence, this systematic error in the measurement can be corrected if it is known. For this purpose, the three-flat test known from the flatness measurement was successfully transferred into the spherical coordinate space for the probing sphere calibration - the three-sphere test

• Development of a closed mathematical solution
• Analysis and simulation
• Uncertainty analysis