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20 May 2009 Fabry-Perot fiber pressure sensor based on white light interferometry and intensity demodulation method
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We have designed an intensity-demodulated sensing system based on Fabry-Perot interferometer and fiber Bragg grating (FBG) for pressure measurement. The structure of the sensor probe is presented. It is an optical fiber extrinsic Fabry-Perot interferometer(EFPI) composed of silica tube and optical fibers. The variable quantity of cavity length of the EFPI is equal to that of silica tube, which has direct proportion to external pressure. The sensing system is interrogated by broadband light. In order to compensate intensity fluctuation, we use an FBG as a narrow band filter to obtain the sensing signal and reference signal from white-light interference fringe returned from EFPI. The sensing signal is in the reflected beam from FBG, and the reference signal is contained in reflected beam and transmitted beam of FBG simultaneously. Then two output light signals are transformed into current signals by two photodiodes. Subsequently two current signals are processed at the same time. After the signals being treated with circuit, the inherent disadvantage of intensity-demodulated sensor is removed. It is also to say the sensing system has immunity from the drift of light source power and fluctuation in fiber attenuation by using only a FBG. Meanwhile, the system has advantages of fast response, simple circuitry, strong ability of intensity compensation and low cost. Experimental results show that the experimental data are consistent with theoretical analysis. The dynamic range of sensor is from 0 to 500KPa, and the resolution reaches to 0.5KPa. The sensing system can be used to measure pressure in inflammable and explosive circumstance such as oil height of super oil storage tanks.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Zhenwu Guo, Weixiang Li, Dapeng Zhang, Yong Pan, Qingbin Meng, Guangwei Liu, Fuwei Ge, and Xian Zhang "Fabry-Perot fiber pressure sensor based on white light interferometry and intensity demodulation method", Proc. SPIE 7283, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 72831J (20 May 2009);

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