In order to solve the problem of weak signal, messy waveform at zero-point and difficult demodulation, when the optical Doppler vibrometer in the long-distance non-contact measurement, in this paper, a new type of optical fiber collimation system is proposed. The system mainly uses an augmented beam shaping system at the end of a small C-lens optical fiber collimator and the Gaussian beam is collimated and optimized by ZEMAX software. Through the coupling test of finished product of optical fiber collimation system, and compared with the signal coupling efficiency of C-lens collimator. The experimental results show that the improved collimation system can meet the working distance of 2 meters, and the coupling efficiency of space return optical up to 6.3%, which greatly enhances the Doppler signal contrast and improves the long-distance optical fiber Doppler vibration measurement accuracy.
Long-distance optical fiber collimation system for Doppler vibrometer
1 Barker L M, Hollenbach R E. Laser interferometer for measuring high velocities of any reflecting surface[J]. Journal of Applied Physics, 1972, 43(11): 4669-4675. DOI:10.1063/1.1660986
2 Wang Y Y, Fish P J. Comparison research of Doppler signal analysis techniques[J]. Journal of Fudan University (Natural Science), 1996, 35(1): 53-61
3 毛士艺, 张瑞生, 许伟武, 等.脉冲多普勒雷达[M].北京:国防工业出版社, 2016.
4 Peng Q X, Meng J H, Wang D T, et al. Design and application of all-fiber velocity interferometer[J]. Acta Photonica Sinica, 2010, 39(11): 2008-2011.
5 Zhu S L, Xu Q S, Liu D S, The analysis of GRIN in optical fiber collimator[J]. Journal of Southwest China Normal University (Natural Science Edition), 2004, 29(3): 379-382.
6 Lu Y Q, Palais J C, Chen Y. Coupling efficiency of single-mode fiber components using GRIN-rod lenses[J]. Fiber and Integrated Optics, 1988, 7(2): 85-107. DOI:10.1080/01468038808222978
7 Xiao Y N. Research on an laser Doppler velocimetry based on DSPs[D]. Wuhan: Wuhan University, 2004: 6-8.
8 Wardell K, Jakobsson A, Nilsson G E. Laser Doppler perfusion imaging by dynamic light scattering[J]. IEEE Transactions on Biomedical Engineering, 1993, 40(4): 309-316. DOI:10.1109/10.222322
9 Talley D, Fortney D, Fiala N, et al. Gated laser Doppler flowmetry using a proximity－contact probe[C]//Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1988, 4: 1849-1850.
10 Özdemir S K, Takamiya S, Shinohara S, et al. A speckle velocimeter using a semiconductor laser with external optical feedback from a moving surface: effects of system parameters on the reproducibility and accuracy of measurements[J]. Measurement Science and Technology, 2000, 11(10): 1447-1455.
11 Shibata T, Shinohara S, Ikeda H, et al. Laser speckle velocimeter using self-mixing laser diode[J]. IEEE Transactions on Instrumentation and Measurement, 1996, 45(2): 499-503. DOI:10.1109/19.492775
12 Yang K T, Chen J. Design of automatic debugging and assembling system for optic fiber collimator[J]. Opto-Electronic Engineering, 2003, 30(2): 36-38, 52.
13 Wang S Q. Ruan Y, Yin D L, et al. The calculation and analizing of the RL of C-lens collimator[J]. Optoelectronic Technology & Information, 2003, 16(1): 24-28.
14 丁东发, 夏君磊.干涉型光纤传感用光电子器件技术[M].北京:科学出版社, 2012.
15 Jiang S, Liu S H, Fang L Z, et al. Return loss in single-mode fiber joints with bevelled endface[J]. Study on Optical Communications, 1994(3): 31-37.
16 Wang G F. Research in advanced erbium-doped fiber amplifier[D]. Beijing: Beijing Jiaotong University, 2009: 27-28.
National Natural Science Foundation of China (617041) and Shaanxi Provincial Key Laboratory of Optoelectronic Testing and Instrumentation Technology Open Fund (2015SZSJ-60-3)
Get Citation: Liu J, Wang W, Chen H B, et al. Long-distance optical fiber collimation system for Doppler vibrometer[J]. Opto-Electronic Engineering, 2018, 45(2): 170621.
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