Research On Displacement Measurement Technology Using Solid-State Laser Heterodyne Interference

Precision inspection technology has common and critical applications in many fields,involving industry,science and technology as well as national defense.With the rapid development of China’s industrial modernization project,the future manufacturing and processing equipment will reflect the development trend of ultra-large,miniaturization,high precision and intelligence.Therefore,the study of precise detection technology is of great significance and application value to promote the development of high-tech industries such as national defense construction,biomedicine and precision manufacturing.In this thesis,based on the analysis of laser interferometry principle,a displacement measurement system based on Mach-Zendel interferometer structure has been designed,which uses a diode-pumped single-wavelength,single-frequency all-solid-state laser as the laser light source,and theoretical analysis and experimental research have been carried out.Based on the idea of absolute distance interferometry,the displacement is measured coarsely using an American Automatic Precision Engineering（API）dual-frequency interferometer to obtain the integer order of magnitude,while the phase difference at the starting and ending positions is measured using a phasemeter,and then the fractional order of magnitude is obtained,and finally the measured value of displacement is obtained by conversion.The main research of this thesis includes the following aspects:Firstly,the research status of laser epi-interferometric displacement measurement technology is summarized,the basic principles,advantages and disadvantages of single-frequency laser and dual-frequency laser interferometric displacement measurement are analyzed,a displacement measurement research system based on the Mach-Zendel interferometer structure has been designed,which employs a 1064 nm single-frequency solid-state laser and acousto-optical frequency-shifting technology,and the feasibility of the measurement system has been analyzed theoretically.The displacement measurement experimental system has been established and the outlier interferometric signal was obtained,and the static and dynamic characteristics of the system have been studied.Second,the signal conditioning circuit modules such as preamplification,band-pass filtering and automatic gain control of the outlier interference signal have been designed,and their functions are verified experimentally in the system,and the results show that the designed signal conditioning circuit is reasonable and feasible.Thirdly,the upper computer program of the digital phase meter in the experimental system has been designed,the phase difference measurement results of the reference signal and the measured signal were obtained and saved.Repeated displacement measurement experiments have been carried out,and the results of the study showed that the standard deviation of repeated measurement was 0.17 μm and 0.23 μm in the range of 100 mm and 200 mm,respectively,and the uncertainty of displacement measurement reached 10^-6 magnitude,and the main factors affecting the accuracy of displacement measurement have been analyzed theoretically.