2-DOF in-Plane Displacement Measurement by Wollaston Prism-based Interferometer

A Wollaston prism (WP)-based interferometer for two-degree-of-freedom (2-DOF) in-plane displacement measurement is developed in this study. The measurement system consists of a heterodyne light source and a high quality WP, and can provide 2-DOF in-plane displacement measurement with high accuracy and stability. Experiments demonstrate that the system has a resolution of 5 nm, and is resistant to outside disturbances as well as internal errors.