Contact on-machine measurement probe error correction method for optical aspheric surface ultraprecision machining

Abstract

Optical aspheric ultraprecision machining requires nanometer-scale on-machine measurement (OMM) techniques, and small probe errors in the contact OMM process can seriously affect the OMM accuracy, thereby reducing machining accuracy. Thus, a master ball-based probe radius error and probe profile error correction method is proposed to analyze the effects of probe radius error and probe profile error on OMM results while ensuring accurate probe alignment to establish an identification and correction model for probe radius error and probe profile error. OMM probe error correction measurement and error compensation machining experiments were conducted to verify the effectiveness of the probe error correction method. After the probe profile error correction measurement, the probe measurement error was changed from 0.436 μm to 0.023 μm. Compared with the uncorrected probe error and the probe radius error correction compensation machining results, the accuracy of the compensation machining after the probe profile error correction compensation was improved by 43 % and 41 %, respectively. Results show that this OMM system probe error correction method is effective in improving OMM accuracy.