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Fiber Fabry-perot Displacement Sensor

Posted on:2009-10-15Degree:MasterType:Thesis
Country:ChinaCandidate:X XiaoFull Text:PDF
GTID:2208360245461459Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
As an important member of optical fiber sensors, fiber Fabry-Perot(F-P) has many advantages, such as small size, high resolution, high sensitivity, compact configuration, high-temperature resistance, and good reliability and flexibility. It can measure many parameters directly, such as high temperature, high pressure, strain, vibration and sonic wave, and can be widely used in most harsh environments, especially in oil and chemical industry, electric power industry.In the dissertation, several key problems of extrinsic Fabry-Perot interferometer are studied deeply and systematically, which include the essential principle ,modulation mechanism and experimental verification of the EFPI optical fiber sensor. The main research efforts are outlined as followings:Firstly, the essential principle of fiber F-P sensor is summarized, and the characteristics of the fiber extrinsic Fabry-Perot interferometer(EFPI) sensor and the fiber intrinsic Fabry-Perot interferometer(IFPI) sensor are compared with each other. Then, two demodulation methods which are intensity demodulation and wavelength demodulation are presented.Secondly, the principle of the intensity demodulation for the fiber-optic Fabry-Perot sensor is described in detail. It includes the setting of the work range and initial F-P cavity length of the F-P sensor that both factors codetermine the F-P sensor sensing in a linear range. According to the theoretical analysis, the performances of the sensing system are simulated, and a linear fitting curve with linearity of 99.8% is obtained. The loss of F-P cavity is analyzed, and the reflectivity of F-P cavity is optimized.Thirdly, the operating principle of the wavelength demodulation for the fiber F-P displacement sensor is introduced. Because the source of the wavelength demodulation system is SLD whose spectrum distributes by Gaussian shape, the measured error formula of actual optical source is deduced, and approved demodulation method for fiber F-P displacement sensing is proposed.At last, we designed the fiber F-P displacement sensor using wavelength demodulation, the theory is validated by the experiment. We found that the relation of measured value and actual value of displacement of reflector in the range from 0 to 60μm is good linear. And it proves that the wavelength demodulation proposed for Gaussian source is applicable. The theory and experimental results is very useful to the F-P displacement sensor using wavelength demodulation.
Keywords/Search Tags:optical fiber sensor, demodulation method, F-P cavity, optimization design
PDF Full Text Request
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