Evaluation of measurement technique for a precision aspheric artefact using a nano-measuring machine

A precision aspheric artefact is measured in 3D by a commercially available nano-measuring machine (NMM) integrated with a contact inductive sensor as the probe. The mathematics of 3D compensation of the error caused by the probe radius is derived. The influence of the probe radius measurement uncertainty on the compensation errors for the 3D measurements is discussed. If the calibration uncertainty of probe radius is 1m and 0.1 m respectively, the compensation errors for a paraboloid artefact are within 100 nm and 10 nm respectively, and the artefact measurement uncertainties are 103 nm and 26 nm respectively. The artefact calibration uncertainty depends more on the uncertainty of the probe radius calibration than the probe radius.