Research On Key Technology Of Grating Interferometric Micro-displacement Measurement System

Considering development of nanotechnology in recent years,micro-displacement detection has increasingly become an important technology in ultra-precision machining and measurement.Among different micro-displacement detection technologies,the grating micro-displacement measurement technology has attracted wide attention benefitting from properties including high accuracy,high resolution,low cost,small size and simple structure.Traditionally,applications of such technology is limited by low beam diffraction efficiency,poor contrast of interference signal and low resolution.In this paper,a high-precision micro-displacement sensor based on grating interference is proposed.Based on nterference effect of zero-order diffracted light and reflected light,combined with four-quadrant detector and subdivision circuit technology,to achieve high-precision displacement measurement.Firstly,different measurement methods are introduced.Benefitting from simple structure and high resolution,the micro-displacement measurement system based on grating diffraction and interference shown advantages for ultracompact sensing systems compared with other traditional methods.Secondly,different methods for micro-displacement detection based on optical grating are analyzed in principle.The basic grating diffraction and interference phenomena are summarized by wave optical method.The single grating structure and the double grating structure are analyzed in Fourier optical principle and grating Taber image principle respectively.The results lay a foundation for the structural design and simulation research of grating-based displacement measurement system.Thirdly,the optical structure of the grating micro-displacement sensor is designed.The working principle of the designed micro-displacement sensor is idiscussedd.The optical structure of both the single grating and the double grating is designed in simulation.The influence of different parameters on the diffraction efficiency is analyzed theoretically.The best design parameters of the grating structure,which can be used for developing principle prototype production of micro-displacement sensor.Finally,combining high-precision photoelectric detection technology and signal processing technology,four-way orthogonal sinusoidal signal is realized.Benefitting from the subdivision circuit and the arc tangent algorithm,the resolution is improved.The experiment resulted shown a resolution of 2.54 nm,a maximum range of 100 ?m,and a sensitivity of0.85% / nm.This work demonstrated optical-grating-based high-performance displacement sensors experimentally,which provides theoretical and technical basis for the design of ultra-compact displacement systems.