Research On Micro-vibration Measurement Techniques Using Single Frequency Solid-state Laser Mach-zehnder Interferometer

With the rapid development of modern engineering and technology,especially in the fields of aerospace,roads,bridges,and the health care,the high-accuracy vibration measurements are needed to be performed.The laser Doppler vibration measurement technology has played an important role in the field of modern vibration measurement technology,because of its advantages of high resolution,wide measurement range,fast response speed,non-contact measurement,etc.Therefore,the research of the laser Doppler vibration measurement technology is of great practical significance.In this thesis,a research scheme of a micro-vibration measurement system based on Mach-Zehnder interferometer has been designed,which uses a diode-pumped 1064 nm single-frequency solid-state laser as the light source,and the theoretical analysis and experimental research have been carried out.The main contents of this thesis include the following aspects:First,the research status of the laser vibration measurement technology using heterodyne interference is summarized,the basic principle of laser vibration measurement using heterodyne interference method is analyzed,a research scheme of micro-vibration measurement has been designed,which employs a light source of single-frequency solid-state laser and a Mach-Zehnder interferometer with double frequency shifters.A theoretical model of the Doppler vibrating signal has been established,and the feasibility of the scheme has been analyzed theoretically.Secondly,an experimental setup of the micro-vibration measurement system using a single-frequency solid-state laser and a Mach-Zehnder interferometer with double frequency shifters has been established,the laser heterodyne interference signal has been obtained,both the static and dynamic characteristics of the system has been studied.Thirdly,a pre-processing circuit module such as the signal amplification and filtering of the laser heterodyne interference signal have been designed,and their functions have been verified by the experiments.The experimental results have shown that the designed pre-processing circuit modules are reasonable and feasible.Finally,the signal acquisition and transmission system as well as the vibration measurement algorithm of the heterodyne interference have been designed on the base of FPGA,and the experimental data of the micro-vibration measurement has been processed,and the frequency and amplitude of the micro-vibration signal has been obtained.Under the existing experimental conditions,the measurement ranges of frequency and amplitude of the micro-vibration signal are 10?200 Hz and 0?15 ?m,respectively.The experimental results have shown that the relative measurement errors of frequency and amplitude of the micro-vibration signal are less than 0.22%and 3.85%,respectively.The main factors affecting the accuracy of micro-vibration measurement have been theoretically analyzed.In summary,the research scheme of the micro-vibration measurement system of Mach-Zehnder interferometer using 1064 nm single-frequency solid-state laser designed in this thesis is feasible,which has laid a solid foundation of the further research of micro-vibration measurement technology in the future.