Paper
8 July 2022 Method and system for phase measurement of the heterodyne interference system
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Abstract
Laser interferometers and grating interferometers are typical optical measurement devices. The measurement resolution and range of the two devices are generally nanometers and meters, so they can meet the needs of high-resolution, largerange measurement. Whether it is a laser interferometer or a grating interferometer, it can be implemented based on a technical route based on the principle of homodyne interference or heterodyne interference. Heterodyne interference is not sensitive to changes in signal amplitude and DC offset, and can effectively avoid measurement errors. To design a highprecision displacement measuring device based on the principle of heterodyne interferometry, the key is whether it can accurately measure the phase change of the measured signal relative to the reference signal. The accuracy of the phase measurement determines the accuracy of the displacement measurement. Phase measurement methods can be divided into two categories: analog method and digital method. In this paper, a high-precision phase measurement system based on FPGA is designed based on the automatic digital phase detection method. The hardware part of the system includes FPGA, high-speed ADC module, signal conditioning circuit, the phase detection algorithm selects the automatic phase detection algorithm, and finally realizes the output display of the phase measurement results. The experimental results show that the deviation between the experimental data of all measurement points and the true value does not exceed 0.1°. Therefore, the accuracy of the phase measurement system designed in this paper is 0.2° and 0.018° resolution.
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Yi Yang, Guochao Wang, Junhao Zhu, Shengtong Wang, Yonggui Wu, and Xinghui Li "Method and system for phase measurement of the heterodyne interference system", Proc. SPIE 12282, 2021 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems, 122821D (8 July 2022); https://doi.org/10.1117/12.2616517
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KEYWORDS
Phase measurement

Field programmable gate arrays

Bandpass filters

Signal processing

Heterodyning

Clocks

Electronic filtering

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