Nanometer-resolution displacement measurement system based on weak feedback effect of dual-frequency laser

Abstract A novel nanometer-resolution displacement measurement system based on weak feedback effect of Zeeman-birefringence dual-frequency laser has been demonstrated. An experimental setup based on an optical feedback dual-frequency laser is developed to realize displacement division and direction discrimination utilizing phase delay between the optical feedback fringes of the two orthogonally polarized lights. The sub-division circuits of fringes are mainly composed of Field Programmable Gate Array (FPGA) and Micro Controller Unit (MCU), can realize 400 subdivisions for each fringe. The FPGA is used to realize the division of integral number fringes, and the MCU is used to realize the “division” of the fractional number fringes through program of look-up table. The total measured displacement is the value sum of both the integral part and the fractional part. A comparison experiment with the HP5529A interferometer was carried out resulting in a linearity of about 5×10 −6 , and a concise theoretical model is given to explain the experimental results. The proposed system has a theoretical resolution as high as 0.791 nm, as well as a function of direction discrimination. Thereby, it can meet some demands of high-precision displacement measurements.

[1]  Zhang Shulian,et al.  A birefringent cavity He–Ne laser and optical feedback , 2004 .

[2]  A Bearden,et al.  Imaging and vibrational analysis with laser-feedback interferometry. , 1993, Optics letters.

[3]  Ming Wang.  Fourier transform method for self-mixing interference signal analysis , 2001 .

[4]  Highly sensitive self-mixing measurement of Brillouin scattering with a laser-diode-pumped microchip LiNdP(4)O(12) laser. , 1999, Optics letters.

[5]  Kenneth T. V. Grattan,et al.  Self-mixing interference inside a single-mode diode laser for optical sensing applications , 1994 .

[6]  G Jin,et al.  Birefringent tuning double frequency He-Ne laser. , 1990, Applied optics.

[7]  É. Lacot,et al.  Laser optical feedback tomography. , 1999, Optics letters.

[8]  P. D. de Groot,et al.  Ranging and velocimetry signal generation in a backscatter-modulated laser diode. , 1988, Applied optics.

[9]  Zhang Shulian,et al.  Intensity modulation characters of orthogonally polarized HeNe lasers with different optical feedback level , 2008 .

[10]  Yan Li,et al.  Optical feedback laser with a quartz crystal plate in the external cavity. , 2003, Applied optics.

[11]  M J Rudd.  A laser Doppler velocimeter employing the laser as a mixer-oscillator , 1968 .

[12]  Lorenzo Scalise,et al.  Laser Doppler vibrometry based on self-mixing effect , 2002 .

[13]  Zhu Jun,et al.  Displacement sensors based on feedback effect of orthogonally polarized lights of frequency-split HeNe lasers , 2003 .