基于高斯型滤波器的FBG振动传感解调技术的研究

【作者】 王舰；

【导师】 忽满利； 任立勇；

【作者基本信息】 西北大学 ， 光学， 2010， 硕士

【摘要】 光纤光栅作为传感器件,通过检测光纤光栅的反射或透射中心波长的变化量能够实现对温度、压力、电流、磁场、振动等物理量的测量。由于光纤光栅传感具有抗电磁干扰能力强、灵敏度高、电绝缘性好、安全可靠、耐腐蚀、可构成光纤传感网等诸多优点,它在航天、航海、石油开采、电力传输、核工业、医疗、科学研究等众多领域均有广阔的应用前景。本文主要研究光纤布拉格光栅振动传感器的解调技术,所做的主要研究内容和取得的研究结果如下：利用耦合模理论分析了光纤布拉格光栅的反射率、反射谱等特性。讨论了光纤布拉格光栅用作应力应变、压力和温度方面传感器的原理和传感特性。介绍了光纤布拉格光栅的解调方法和复用技术。研究了光纤布拉格光栅作为传感器件受轴向和径向静态应力产生应变的特性,使用光纤光栅解调仪对光纤布拉格光栅反射中心波长测量,结果表明,光纤光栅的应力应变和压力传感实验结果与理论分析相符。为了解决传统匹配光纤光栅解调法的动态解调范围不足问题,提出了通过使用带宽较宽的高斯型滤波器替代匹配光栅来提高动态解调范围的方案,理论上对这种方案进行了分析和讨论,研究了确定工作点的有效方法。实验上采用3dB带宽为0.374nm的滤波器替代3dB带宽为0.241nm的匹配光栅,对这种解调方案进行了实验,实现了对1000Hz的振动高频有效解调,同时将系统的动态测量范围从0.29nm提高到0.378nm,在该动态范围内,系统测量灵敏度为3.6mv／pm,误差为2.7%。更多还原

【Abstract】 The fiber grating can be used as the sensor to get physical quantities such as temperature, stress, current, magnetic field, vibration etc by detecting the variation of reflection or transmission center wavelength. Because of the sensor advantages of high electromagnetic interference resistance and sensitivity, fine electrical insulation, good safety and reliability, resistant and easy to constitute optical fiber sensors network, the fiber grating has potential application in aerospace, navigation, oil exploration, power transmission, nuclear industry, medical science, scientific research and other fields. This thesis focuses on the demodulation technology of fiber Bragg grating sensor, the main research content and results are as follows.The reflectivity and reflection spectrum of fiber Bragg grating were analyzed by the fiber grating coupling theoretical model. Based on this, the principle and feature of fiber grating sensing in stress strain, pressure and temperature were discussed. The demodulation method and multiplexing technology of fiber Bragg grating were introduced as well.The effect of axial and radial direction force on fiber Bragg grating sensing was discussed. The experimental results of fiber grating sensing coincided with the theoretical analysis, by measuring the center wavelength of reflection spectrum of fiber Bragg grating with the interrogator.In order to overcome the shortage of dynamic measure range in traditional fiber grating demodulation, Gaussian filter with broader bandwidth was introduced to replace matching grating. After theoretical analysis, effective method to obtain work-point was discussed. The demodulation experiment was performed by replacing matching-grating (3dB,0.241nm bandwidth) with filter (3dB,0.374nm bandwidth). This system achieved effective vibration demodulation at 1000Hz and broadened the dynamic measure range from 0.29nm to 0.378nm. In addition, within this range, the sensitivity and measurement error of the system is 3.6 mv/pm and 2.7% respectively.更多还原