High-resolution three-degrees-of-freedom motion errors measuring system for a single-axis linear moving platform

In this study, a high-resolution three-degrees-of-freedom (3-DOF) motion error measuring system based on interference is described. it can simultaneously measure the linear displacement and two angular errors of a single-axis linear moving platform. The displacement is measured using a polarization interference technique and the two angular errors are also measured based on the geometry optical theorem. The verification results show that the resolution is about 20 nm. The 3-DOF measurement system detected displacements relative to a measurement mirror move with an accuracy of about +/- 8 mu m for a measuring range of 50 mm, and detected the angular errors with a related accuracy of about +/- 2 arc sec for a measuring range of +/- 100 arc sec.