Adjustment of Phase Shift of Measurement Signals in an Optical Encoder from the Parameters of an Analyzing Scale

Abstract

Optical sensors of linear displacements with diffraction gratings serving as the measurement scales are investigated. A method of stabilization of the phase difference of quadrature measurement signals, consisting in the use of an analyzing scale with a special structure, is proposed. A design of an optical encoder based on the method is proposed. Mathematical simulation of the phase shift of the measurement signals as a function of the parameters of the diffraction grating is performed, and the results of the simulation are presented. The RCWA method is used to simulate the passage of radiation through the optical system. The optimal parameters of the structure of the analyzing scale are calculated. Experimental investigations of a mock-up of the encoder are performed and results of measurements of the phase difference of the measurement signals are presented.