15 November 2011 An interference signal processing method for displacement measurement by dual wavelength and single grating
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Proceedings Volume 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation; 83211A (2011) https://doi.org/10.1117/12.904076
Event: Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 2011, Yunnan, China
Abstract
Displacement measurement by dual wavelength and single grating integrates the single grating diffraction theory and the heterodyne interference theory. By taking advantage of the two theories, it solves the contradiction between large range and high precision in grating displacement measurement quite well. In order to obtain nanometer resolution and nanometer precision, high-power subdivision of interference fringe must be realized accurately. According to phase demodulation theory for heterodyne interference signal, a digital phase measuring method is proposed by combining frequency-mixing technique and pulse-filling method. The whole signal processing part, which is based on FPGA and PLL, has been designed to realize the integer period measurement and high-powered subdivision of the decimal phase. Through experiments, it is validated that the phase range is [-180°, 180°], and the phase measurement resolution and the phase precision are above 0.03° and 0.1°, respectively. Moreover, the displacement measurement resolution and the displacement precision, corresponding to the phase indexes, are 0.167nm and 0.556nm, respectively.
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Guochao Wang, Shuhua Yan, Dongxing Yang, Weihong Zhou, Xuedong Xie, "An interference signal processing method for displacement measurement by dual wavelength and single grating", Proc. SPIE 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 83211A (15 November 2011); doi: 10.1117/12.904076; https://doi.org/10.1117/12.904076
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