Optical Grating Diffraction and Optical Beat Frequency Principle-Based Ultrahigh Resolution Displacement Measurement System

Abstract

This research presents a novel displacement measurement system that combines optical grating diffraction, the optical Doppler principle, and the optical beat frequency principle. The system utilizes a double-frequency laser device, an interferometer, a measuring grating, and an electrical signal processing unit. By dividing the laser into reference light and measuring light and analyzing the beat frequency signal generated by the interaction of the measuring light and the reference light, the system achieves precise linear displacement measurements in two directions. The system offers sub-nanometer-grade or even higher resolution and accuracy, simultaneous measurement of horizontal large-stroke displacement and horizontal displacement, and exhibits advantages such as environmental insensitivity, high measurement accuracy, compact size, and lightweight. The proposed system finds potential applications in ultraprecise workpiece platform position measurement systems, contributing to the overall performance improvement of lithography machines.