Design Of Super-Heterodyne Absolute-Distance Interferometric System Using Dual-Frequency Solid-State Laser

Absolute-distance measurement is a kind of no-guideway measurement,which plays a vital role in many scientific and technological fields such as advanced manufacturing,aerospace,military and artificial intelligence due to its wide measurement range and high measurement accuracy.Therefore it is of great significance to carry out the research on absolute-distance measurement technology.In this thesis,a synthetic-wave super-heterodyne absolute-distance interferometric system based on the structure of Mach-Zehnder interferometer has been designed,which uses a twocavity dual-frequency Nd:YAG laser at 1064nm as a light source.The fractional order of the synthetic-wave interference fringes can be determined by measuring the phase-difference of both super-heterodyne interference signals,and the integer order of the synthetic-wave interference fringes can be uniquely determined by preliminary estimating the measured distance,as a result the absolute-distance measurement can be realized.The main research contents of this thesis include the following aspects:First,the research background and status at home and abroad of the absolute-distance measurement have been briefly described,and the research contents of this thesis have been determined.Secondly,two kinds of commonly used interferometers have been introduced,the advantages and disadvantages of heterodyne and super-heterodyne interferometry using dual-frequency laser have been compared and analyzed.On this basis,a scheme of super-heterodyne absolute-distance interferometric system using the dual-frequency solid-state laser has been designed and introduced in detail.Thirdly,an optical system of super-heterodyne interferometric measurement by use of dualfrequency solid-state laser has been established,its static and dynamic characteristics have been tested experimentally.A signal conditioning circuit has been designed,and the modules of amplification and filtering have been verified experimentally.An acquisition program for the phase data has been designed using software of Lab VIEW,the phase difference measurement in real time and the storage of measurement results have been realized.Fourthly,the synthetic wavelength calibration and absolute distance measurement have been investigated experimentally,the measurement data have been sampled and processed.The experimental results have shown that the accuracy of absolute-distance measurement is better than 6.9 × 10-4 in a range of 0～1.143 m,and the measurement accuracy has been analyzed.In a word,in this thesis,a superheterodyne absolute distance interferometry system is designed using quadrature demodulation PDH frequency-stabilized 1064nm dual-cavity dual-frequency Nd:YAG laser as the light source and conducted preliminary experimental research.It has laid a solid foundation for the future research on long-distance,high-precision absolute distance interferometry technology.