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Open AccessArticle

Measurement Method for Nonlinearity in Heterodyne Laser Interferometers Based on Double-Channel Quadrature Demodulation

Institute of Ultra-Precision Optoelectronic Instrument Engineering, Harbin Institute of Technology, Harbin 150001, China
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Author to whom correspondence should be addressed.
These authors contribute equally to this study.
Sensors 2018, 18(9), 2768; https://doi.org/10.3390/s18092768
Received: 19 July 2018 / Revised: 18 August 2018 / Accepted: 21 August 2018 / Published: 22 August 2018
(This article belongs to the Special Issue Optoelectronic and Photonic Sensors)
The phase quadrature measurement method is capable of measuring nonlinearity in heterodyne laser interferometers with picometer accuracy whereas it cannot be applied in the new kind of heterodyne interferometers with bidirectional Doppler frequency shift especially in the condition of non-uniform motion of the target. To solve this problem, a novel measurement method of nonlinearity is proposed in this paper. By employing double-channel quadrature demodulation and substituting the external reference signal with internal ones, this method is free from the type of heterodyne laser interferometer and the motion state of the target. For phase demodulation, the phase differential algorithm is utilized to improve the computing efficiency. Experimental verification is carried out and the results indicate that the proposed measurement method achieves accuracy better than 2 pm. View Full-Text
Keywords: laser interferometry; heterodyne laser interferometer; nonlinearity measurement; double-channel quadrature demodulation laser interferometry; heterodyne laser interferometer; nonlinearity measurement; double-channel quadrature demodulation
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Fu, H.; Ji, R.; Hu, P.; Wang, Y.; Wu, G.; Tan, J. Measurement Method for Nonlinearity in Heterodyne Laser Interferometers Based on Double-Channel Quadrature Demodulation. Sensors 2018, 18, 2768.

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