Carrier-separating demodulation of phase shifting self-mixing interferometry. (March 2017)

• Record Type: Journal Article
• Authors: Tao, Yufeng; Wang, Ming; Xia, Wei
• Is Part Of: Optics & laser technology. Volume 89(2017)
• Page Start: 75
• Page End: 85
• Publication Date: 2017-03
• Subjects: Carrier-separating -- Empirical mode decomposition -- Wavelet transform -- Phase extraction -- Computing efficiency; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2016.08.013
• Languages: English
• ISSNs: 0030-3992

Abstract

Abstract: A carrier separating method associated with noise-elimination had been introduced into a sinusoidal phase-shifting self-mixing interferometer. The conventional sinusoidal phase shifting self-mixing interferometry was developed into a more competitive instrument with high computing efficiency and nanometer accuracy of λ / 100 in dynamical vibration measurement. The high slew rate electro-optic modulator induced a sinusoidal phase carrier with ultralow insertion loss in this paper. In order to extract phase-shift quickly and precisely, this paper employed the carrier-separating to directly generate quadrature signals without complicated frequency domain transforms. Moreover, most noises were evaluated and suppressed by a noise-elimination technology synthesizing empirical mode decomposition with wavelet transform. The overall laser system was described and inherent advantages such as high computational efficiency and decreased nonlinear errors of the established system were demonstrated. The experiment implemented on a high precision PZT (positioning accuracy was better than 1 nm) and compared with laser Doppler velocity meter. The good agreement of two instruments shown that the short-term resolution had improved from 10 nm to 1.5 nm in dynamic vibration measurement with reduced time expense. This was useful in precision measurement to improve the SMI with same sampling rate. The proposed signal processing was performed in pure time-domain requiring no preprocessing electronic circuits. Highlights: Carrier separating method required the optimal phase modulation depth was 0.5 rad. Pure time-domain signal processing avoided the complicated transforms or circuits. Quadrature signals were extracted by carrier-separating and enhanced by EMDWT. Non-uniform vibration measurement performed with different shapes or amplitudes. Comparison with Ploytec-5000 LDV shown the potential value of present method.