基于拉曼散射的光纤测温系统设计与研究

发布时间：2018-05-26 20:35

  本文选题：分布式光纤 + 拉曼散射　； 参考：《大连海事大学》2017年硕士论文

【摘要】：近年来,分布式光纤测温技术作为一种温度测量手段得到了越来越多的运用。相比于传统的点式温度传感器,分布式光纤测温技术以其抗电磁干扰、测量区域广、稳定性高和布线简单等特点受到了越来越多的重视。本文针对传统温度测量技术在远距离条件下的测温受限问题,设计了一种基于拉曼散射技术的分布式光纤测温系统,主要完成了以下几个部分工作:1、研究拉曼散射技术的基础理论,运用了一套线性化的温度解调公式。将拉曼散射公式进行了泰勒展开,得出了拉曼散射信号中反斯托克斯光对温度尤为敏感的理论公式;为了消除光源功率波动和APD温漂的影响,从而使用了斯托克斯信号解调反斯托克斯信号的方法,对该公式进行了分析和线性化处理,最后使用线性化公式解调温度。2、根据系统的设计指标,完成了各个模块的选型,搭建起实验室环境下的系统框架。光纤测温系统中各个性能参数指标不能单独进行分析,每个指标都和模块参数息息相关,在研究了每个模块参数对性能指标影响的前提下,选择了合适的模块完成了整个系统的搭建。3、针对采集到的拉曼散射光及其系统噪声类别,分析了各种信号处理技术的特点,并提出了温度解调补偿算法。对于拉曼散射光非常微弱和难以采集的特点,分析了几种适合本系统去噪要求的微弱信号处理方法。同时使用一种衰减补偿算法将整个光纤线上相同环境温度的测温点信号补偿成一条水平曲线,用以解决拉曼散射光光强随光纤距离变长而减弱的问题。4、完成了分布式光纤测温系统软件的设计,并做了大量的性能相关实验。设计了数据采集与处理、温度标定与解调、温度显示与异常报警、数据保存等功能,在实验室环境下验证了各种性能指标。实验结果证明,该系统在监测3000m范围时可以达到空间分辨率1.5m、测温精度±2℃等指标。
[Abstract]:In recent years, distributed optical fiber temperature measurement technology as a means of temperature measurement has been used more and more. Compared with the traditional point temperature sensor, distributed optical fiber temperature measurement technology has attracted more and more attention for its characteristics of anti-electromagnetic interference, wide measurement area, high stability and simple wiring. In this paper, a distributed optical fiber temperature measurement system based on Raman scattering is designed to solve the problem of limited temperature measurement of traditional temperature measurement technology under remote conditions. The following parts have been completed: 1. The basic theory of Raman scattering has been studied and a set of linearized temperature demodulation formula has been applied. The Taylor expansion of Raman scattering formula is carried out, and the theoretical formula of anti-Stokes light sensitivity to temperature in Raman scattering signal is obtained, in order to eliminate the influence of light source power fluctuation and APD temperature drift. The method of demodulating anti-Stokes signal with Stokes signal is used, and the formula is analyzed and linearized. Finally, the temperature of demodulation by linearization formula is used to demodulate the temperature. According to the design index of the system, the selection of each module is completed. Set up the system frame in the laboratory environment. Each performance parameter index in fiber optic temperature measurement system can not be analyzed separately, and each index is closely related to module parameter. Under the premise of studying the influence of each module parameter on performance index, The appropriate module is selected to complete the whole system. The characteristics of various signal processing techniques are analyzed according to the Raman scattering light collected and the noise types of the system. A temperature demodulation compensation algorithm is proposed. For the characteristics of very weak Raman scattering light and difficult to be collected, several weak signal processing methods are analyzed which are suitable for the de-noising requirement of the system. At the same time, a attenuation compensation algorithm is used to compensate the signal of the same ambient temperature point in the whole fiber line into a horizontal curve. In order to solve the problem that the intensity of Raman scattering light decreases with the increase of fiber distance, the software of distributed optical fiber temperature measurement system is designed, and a large number of performance experiments are done. The functions of data acquisition and processing, temperature calibration and demodulation, temperature display and abnormal alarm, and data preservation are designed. The experimental results show that the system can achieve the spatial resolution of 1.5m and the accuracy of temperature measurement 卤2 鈩，

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