Real-time phase delay compensation of PGC demodulation in sinusoidal phase-modulation interferometer for nanometer displacement measurement.

As the phase delay between the carrier component of the detected interference signal and the carrier has adverse effect for phase generated carrier (PGC) demodulation, it is essential to compensate the phase delay to improve the accuracy of precision displacement measurement in sinusoidal phase-modulation interferometer (SPMI). In this paper, a real-time phase delay compensation method is proposed by regulating a compensating phase introduced to the carrier to maximize the output of the low pass filter so as to make the carrier synchronize with the interference signal. The influence of phase delay for PGC demodulation is analyzed and the method for real-time phase delay compensation is described in detail. The simulation of the method was performed to verify the validity of the phase delay compensation algorithm. A SPMI using an EOM was constructed and several comparative experiments were carried out to demonstrate the feasibility of the proposed method. The experimental results show that the phase delay can be compensated accurately in real time, and nanometer accuracy is achieved for precision displacement measurement.

[1]  Xun Li,et al.  An Efficient Approach for Time-Domain Simulation of Pulse Propagation in Optical Fiber , 2010, Journal of Lightwave Technology.

[2]  David A. Jackson,et al.  Improvement on phase generated carrier technique for passive demodulation of miniature interferometric sensors , 1994 .

[3]  Dongmei Guo,et al.  Sinusoidal phase-modulating self-mixing interferometer with nanometer resolution and improved measurement velocity range. , 2015, Applied optics.

[4]  Hermann Lin,et al.  Modified phase-generated carrier demodulation compensated for the propagation delay of the fiber. , 2007, Applied optics.

[5]  Fuh-Hsin Hwang,et al.  An improved sensitivity normalization technique of PGC demodulation with low minimum phase detection sensitivity using laser modulation to generate carrier signal , 2013 .

[6]  Xiang-zhao Wang,et al.  Sinusoidal phase-modulating laser diode interferometer insensitive to the intensity modulation of the light source , 2009 .

[7]  T Suzuki,et al.  Real-time displacement measurement with a two-wavelength sinusoidal phase-modulating laser diode interferometer. , 2000, Applied optics.

[8]  D. Marioli,et al.  A high‐frequency sinusoidal phase‐modulation interferometer using an electro‐optic modulator: Development and evaluation , 1991 .

[9]  Shihua Zhang,et al.  Precision measurement of refractive index of air based on laser synthetic wavelength interferometry with Edlén equation estimation. , 2015, The Review of scientific instruments.

[10]  O. Sasaki,et al.  Sinusoidal phase modulating interferometry for surface profile measurement. , 1986, Applied optics.

[11]  Yuliang Liu,et al.  An Ameliorated Phase Generated Carrier Demodulation Algorithm With Low Harmonic Distortion and High Stability , 2010, Journal of Lightwave Technology.

[12]  T Suzuki,et al.  Laser-diode interferometer with a photothermal modulation. , 1999, Applied optics.

[13]  G. B. nsch,et al.  Measurement of the refractive index of air and comparison with modified Edl?n's formulae , 1998 .

[14]  D. Guo,et al.  Self-mixing interferometer based on sinusoidal phase modulating technique. , 2005, Optics express.

[15]  Xuefeng Wang,et al.  A sinusoidal phase-modulating fiber-optic interferometer insensitive to the intensity change of the light source , 2003 .

[16]  O. Sasaki,et al.  Sinusoidal phase-modulating laser diode interferometer insensitive to intensity modulation for real-time displacement measurement with feedback control system , 2012 .

[17]  T. Giallorenzi,et al.  Homodyne Demodulation Scheme for Fiber Optic Sensors Using Phase Generated Carrier , 1982 .

[18]  Yanbiao Liao,et al.  Measurement of the phase shift between intensity and frequency modulations within DFB-LD and its influences on PGC demodulation in a fiber-optic sensor system. , 2013, Applied optics.

[19]  O. Sasaki,et al.  Profile measurement of thin films by backpropagation of multiple-wavelength optical fields with two sinusoidal phase-modulating interferometers , 2015 .

[20]  S. Michael,et al.  Composite operational amplifiers: Generation and finite-gain applications , 1987 .

[21]  Takamasa Suzuki,et al.  Real-time vibration measurement using a feedback type of laser diode interferometer with an optical fiber , 1997 .