Grating Interferometer with Redundant Design for Performing Wide-Range Displacement Measurements

Abstract

Grating interferometers that use large two-dimensional grating splice modules for performing wide-range measurements have significant advantages for identifying the position of the wafer stage. However, the manufacturing process of large two-dimensional grating splice modules is very difficult. In contrast to existing redundant designs in the grating line dimension, we propose a novel interferometric reading head with a redundant design for obtaining wide-range displacement measurements. This interferometric reading head uses a one-dimensional grating splice module, and it was observed to be compatible with two orthogonal gratings. We designed a grating interferometer system composed of four reading heads to achieve a wide range of measurements and verified it using ZEMAX simulation. By conducting experiments, we were able to verify the compatibility of the reading head with gratings possessing different grating line directions; the measurement noise was found to be less than 0.3 nm.

A Compact and High-Precision Three-Degree-of-Freedom Grating Encoder Based on a Quadrangular Frustum Pyramid Prism

“…Scholars have also conducted a series of research to achieve multi-DOF and compactness. Multi-DOF mostly comprises two to three DOF [34][35][36][37] and four to six DOF [32,[38][39][40][41]. However, only a few scholars, mainly led by enterprises, such as the LIP6031D series products proposed by Heidenhain in July 2021, have researched miniaturization [42,43].…”