Study On Signal Processing Method Of Phase-modulated Laser Interferometer

In recent years, with the rapid development of MEMS, ultra-precision processingtechnology, many measuring instruments are developed to the nanometer or evensub-nanometer resolution and accuracy. The laser interferometer measurementtechnology featured with high accuracy, a wide displacement measurement range.In the laser interferometer measurement, signal processing method greatly affectsthe measurement accuracy. To achieve nanometer measurement accuracy, and laserinterferometer research focuses on the interferometric signal processing methods.The paper introduces the principle of phase-modulation interferencedisplacement measurement system with polarization, how to demodulate the signalof the phase modulation measurement system is the focus of this thesis.Withvirtual instrument technology, phase modulation of phase-modulation interferencedisplacement measurement system was designed on LabVIEW software platform.The main content of the thesis:1. The the PCG signal demodulation method and PLL demodulation method wereanalyzed and compared, the phase locked loop demodulation method for phase-modulated laser interferometry displacement measurement was employed todemodulate signal phase and displacement.2. Phase-locked loop demodulation was carried out a detailed study and analysisof the method for each set of key parameters. Based on virtual instrumenttechnology, the phase-modulated laser interferometric signal processing systemwere established with PCI6221data acquisition card as the hardware core,LabVIEW software platform was used to build data collection procedures and PLLdemodulation software algorithms, and the signal processing system can achievethe demodulated interference signal in real time.3. On the LabVIEW software platform, modular programming ideas wereproposed for software optimization, and ultimately gives a measure of theexperiment.Demodulation method with PLL can improve the resolution of the signal, themodulated signal is easy to realize fine interpolating subdivision, while ensuringthat the signal is not significantly affected by detecting the signal flow direction.This phase modulation interferometer provides an effective signal processing method for phase-modulation interference.