Absolute Calibration of the Rotary Encoder Considering the Influence on-Machine for Development of High-Speed Nanoprofiler

The development of a high-speed nanoprofiler is essential for developing the next generation of ultraprecision aspheric mirrors. The purpose of this study is to develop a new high-speed nanoprofiler that traces the normal vector of an aspheric mirror surface. The method of measurement adopted here is based upon the accuracy of a rotation goniometer. In order to attain a form measurement accuracy of PV1nm, it is necessary to improve the angle measurement accuracy. In this study, we equip a nanoprofiler with a rotary encoder that is calibrated in order to accomplish this objective, using a national standard machine. Consequently, this rotary encoder can be calibrated with an accuracy of ±0.12 μrad when considering the influence of installing the encoder on the nanoprofiler.