Research On The Vibration Signal Demodulation Of Laser Interferometer Base On LabView

Precision of measurement technology determines the ability of humans to explore the unknown world.In many measurement technologies,the technology based on the optical interference method has many advantages such as high precision,anti-electromagnetic interference and simple structure.So it gets a lot of applications,and has great potential for development.In the high-precision measuring devices based on method of optical interferometry,demodulation technique for measuring signal is a key point and it determines the device performance.The key to signal demodulation technique is demodulation algorithm.Pursued to be more accurate,more efficient algorithms and built on signal demodulation system is the eternal theme of the developing optical interferometry techniques.This project is focused on the characteristics of many demodulation algorithms and seeks a new algorithm to achieve.Then we built on demodulation system and demodulated the interference signal to verify functionality and performance of the algorithm.The main contents concluded in the paper as follows:1?Firstly,we analyzed the present situation of the development of optical interferometry techniques,and introduced and evaluated a variety of signal demodulation algorithm.We combine the characteristics of various demodulation methods to expect to achieve better demodulation algorithm.2?Secondly,we discussed in detail the principles and theory derivation of demodulation algorithm,then selected the policy analysis and demodulation parameters,given the appropriate demodulation parameters.Specific approach is to analyze the characteristics of the signal spectrum,given the bandwidth of analog circuit design,principle of carrier frequency selecting and modulation amplitude.The above work provides a solid theoretical foundation and the basis for selecting the elements and designing demodulation system.3?Thirdly,In this chapter,we analyzed the needs of each part of the system,and then proposed the design of demodulation system,given the principles of device selection,specific embodiments and key technologies designed to note.Then we offered the practices of each part,include analog circuits for optical detection,acquisition and pre-processing portion of the signal,demodulation software and carrier output section.4?Then,we designed demodulation software.According to the algorithm theory,we given the various parts of the demodulation software program flow chart.Then we used LabView implementation of each part,and compiled the PC software used to demodulate the signal.5?And then In this chapter we tested and simulated demodulation systems.The first step is the software simulation.What's more,we set up a system of optical interferometry to measure the real displacement and vibration signals.We verified and tested the functionality and performance of the software.This project has designed a laser interferometer signal demodulation system and realized an improved PGC algorithm.We have developed software and use it to demodulate signal of laser interferometer.The final result showed that the system can demodulate the signal in real time and the dynamic range of the signal reaches 139.31 dB.What' more,the precision reaches 1×10-5rad/Hz1/2.