Brillouin温度测量仪信号探测与处理技术研究

发布时间：2019-03-17 18:14

【摘要】：分布式光纤布里渊传感技术是近年来发展起来的一项新的传感技术,它具有测量精度高、传感距离远等优点,并且可以同时对温度和应变进行分布测量,因此非常适用于处于恶劣环境中的大型工程结构的健康监测,具有非常重要的应用前景本文基于BOTDA技术原理,对Bri1llouin温度测量仪的信号探测与处理技术进行了较为深入和系统的研究。提出了利用声光和电光相结合进行移频的方法,解决了现有基于电光移频的BOTDA技术原理中存在两边带对泵浦光能量的相互抵消问题。设计了以工控机为核心的信号探测、处理与控制电路软硬件,电路设计包括以FPGA和高速放大器构成的可调窄脉冲电路和光电探测电路,其中可调窄脉冲电路可以由计算机控制输出任意脉冲宽度的窄脉冲,最小脉宽可达5ns；光电探测电路由I/V转换电路、信号放大滤波电路和电压转换电路等组成,可以对脉宽为10ns,强度小于-50dBm的光脉冲信号进行探测。信号处理采用了对采样数据的预处理、BOCAX积分、小波变换等方法,提高了测量数据的信噪比。采用非线性最小二乘法对测量数据进行洛伦兹拟合,最后通过布里渊谱计算出分布温度数据。搭建了分布式光纤布里渊温度测量系统实验装置,通过实验温度分辨率达到10C,空间分辨率达到1m。
[Abstract]:Distributed optical fiber Brillouin sensing technology is a new sensing technology developed in recent years. It has the advantages of high measurement precision, long sensing distance, and can simultaneously measure temperature and strain distribution. Therefore, it is very suitable for the health monitoring of large-scale engineering structures in harsh environment, and has a very important application prospect. This paper is based on the principle of BOTDA technology. The signal detection and processing technology of Bri1llouin temperature measuring instrument is studied deeply and systematically. The method of combining acousto-optic and electro-optic to shift frequency is put forward, which solves the problem of mutually counteracting the energy of pump light in the principle of BOTDA based on electro-optic frequency shift. The hardware and software of signal detection, processing and control circuit based on industrial control computer are designed. The circuit design includes adjustable narrow pulse circuit and photoelectric detection circuit composed of FPGA and high speed amplifier. The adjustable narrow pulse circuit can be controlled by computer to output narrow pulse with arbitrary pulse width, and the minimum pulse width can reach 5 ns. The photoelectric detection circuit is composed of I / V conversion circuit, signal amplifying filter circuit and voltage conversion circuit. It can detect the optical pulse signal whose pulse width is 10 ns and the intensity is less than-50dBm. In signal processing, the signal-to-noise ratio (SNR) of the measured data is improved by pretreatment of sampled data, BOCAX integral, wavelet transform and so on. The nonlinear least square method is used to fit the measured data in Lorentz. Finally, the distribution temperature data are calculated by Brillouin spectrum. The experimental equipment of distributed optical fiber Brillouin temperature measurement system is built. The experimental temperature resolution reaches 10C and the spatial resolution reaches 1m.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH811

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