Development of a polar-coordinate optical encoder: Principle and application

A polar-coordinate optical encoder that can realize synchronous measurement of angular and radial displacements is introduced. It has potential application in concurrent monitoring of radial and angular motions for rotating spindles and in real-time detection and compensation of eccentricity error for rotary stages. We explain its operating principle and develop a prototype. Experimental results demonstrate the feasibility and effectiveness of the proposed optical encoder in polar-coordinate displacement measurement.