【作者】 曹平；

【导师】 李志全；

【作者基本信息】 燕山大学 ， 检测技术与自动化装置， 2010， 硕士

【摘要】 光纤Bragg光栅(Fiber Bragg grating FBG)作为传感器,具有灵敏度高、抗电磁干扰、安全可靠、可以测量不同物理参量等优点,引起了普遍的重视。为了实现多点、分布式信号传感测量,人们提出基于波分、时分、空分复用技术的多种复用方案。这些复用技术中,波分复用和空分复用相结合的复用技术具有较高的精度,但是解调速度慢。本文提出了基于倾斜光栅的FBG复用解调系统,只对波长变化的FBG解调,优化了解调规则,提高了解调速度。具体内容包括:首先,介绍了光纤光栅的分析方法,并利用耦合模理论和转移矩阵法对光纤光栅进行仿真。研究了FBG的温度、应变传感模型,并分析了常用的FBG解调方案。其次,设计了基于倾斜光栅的FBG复用解调系统,分析了系统中关键器件的性能和工作原理。研究了光纤F-P可调谐滤波器的特性,并采用梳状滤波器对其进行非线性标定。提出采用经验模态分解(Empirical mode decomposition EMD )方法对FBG反射谱进行消噪处理,并对EMD方法进行理论研究。最后,对光纤F-P可调谐滤波器标定系统进行实验研究,得到透射波长和驱动电压之间的关系曲线。对EMD方法的滤波效果进行了仿真研究,并通过实验验证EMD方法对提高系统测量精度的作用。利用所设计的系统分别进行温度、应变传感实验,实验表明实验值和理论值相吻合。与传统复用系统进行解调等待时间比较,验证了所设计系统的可行性。更多还原

【Abstract】 Fiber Bragg gratings(FBG) used as sensors have been attracted considerable attention due to their high sensitivity, immunity to electric interference, safety and capability of measuring different kinds of physical parameters. Many multiplexing schemes have been proposed based on techniques including wavelength, time, and space division multiplexing to meet multipoint and distributed sensing. Among these techniques, the Wavelength and spatial division combined multiplexing approach has high resolution, but, it is relatively slow. In this paper, a FBG multiplexing demodulation system based on tilted fiber Bragg grating is proposed. The multiplexing technique only demodulates the FBG sensors whose peak wavelength is shifting, so that the demodulation rule is optimized, also the demodulation rate is improved. The primary content includes:Firstly, the analysis methods of fiber grating are introduced, also the simulation of fiber grating using coupled-mode theory and the transfer matrix method is established. The temperature and strain sensing models of FBG are researched, and the commonly FBG demodulation schemes are analyzed. Secondly, the FBG multiplexing demodulation system based on tilted fiber Bragg grating is designed, and the performance and working principle of main devices is analyzed. The characteristics of fiber Fabry-Perot tunable filters are researched, and the comb filter is used to calibrate its nonlinear. Empirical mode decomposition method is proposed to denoise the reflection spectrum of FBG.Finally, transmission wavelength of fiber Fabry-Perot tunable filters as a function of the scanning voltage is obtained though experiment. The filtering effectiveness of EMD is simulated, also through contrast experiment proved the measurement accuracy is improved. The experiments on temperature and strain are done respectively, of which the results show that the experimental data is consistent with theoretical data. Comparing the average delay time of this system with conventional system, the feasibility of the proposed system is well proved.更多还原