Study On The Key Technology Of The Phase Modulated Laser Interference Displacement Measuring System

Laser interferometers combine optical testing theory and electronics technology,enabling fast, high-precision measurement, widely used in precision manufacturing,and measurement fields. Laser interferometer can achieve nanometer precision, butsusceptible to environmental conditions like temperature,pressure,turbulence, andacqiuring higher precision, signal quality and signal processing methods should befurther improved. With electronic technology,laser interferometers have beendeveloped continuously new principle, new structure, and strive to realize the system’s reliability and miniaturization, improving the performance of the practicalapplication.Based on the analysis of existing typical laser interferometer principle, laserinterferometer with phase modulation method was developed with the structure of apolarization Michelson interferometer, which can acquire single modulatedinterference signal to achieve a fine interpolating subdivision and to detect the signalflow’s directions, this method reduces the error of some multi-channel signalprocessing, simple structurecan achieve high-precision measurements.This paper analyzes the configuration of the laser displacement measuringinterferometer with phase modulation, including optical design and a signalprocessing. signal processing for PZT driver, a photoelectric detecting circuit andsignal demodulation section were disscused. In optical polarization interferometermeasurement system, PZT was employed to modulate beam optical path lengthperiodically, phase-modulated signals obtained and amplified by circuit,The signalwas then send into the computer to demodulate the measurement signal with thedisplacement with LabVIEW software.Finally, the experiment system has been set up and comparing with Renishaw’sXL-80laser interferometer. The design of the proposed phase-modulated laserinterferometric displacement measuring system retains the simple structure of theconventional laser interferometer, the measurement sensitivity and accuracy is alsogreatly improved.