布里渊散射论文：外差检测BOTDR温度和应变传感技术研究.docVIP

布里渊散射论文：外差检测BOTDR温度和应变传感技术研究 【中文摘要】本文介绍了基于布里渊散射的温度和应变传感研究现状,分析了光纤中的布里渊散射特性以及对温度和应变的传感理论,建立了布里渊散射频移和强度与光纤中温度和应变的对应关系。利用布里渊散射和瑞利散射强度之比来消除光纤损耗所带来的影响,从而修正布里渊散射强度的相对变化量,为外差检测BOTDR温度和应变传感技术奠定了理论基础。对外差检测BOTDR传感系统和信号处理方案进行了研究,并对下变频子系统中频率综合器模块的控制进行了重点研究。根据频率综合器的控制要求,设计了微波频率综合器的控制软件使其能够输出所要求的频率分量。采用了将Golay互补序列应用于BOTDR光纤传感系统的方法,通过对Golay互补序列的时域和频域特性进行理论分析,设计了基于Max+plus II平台的Golay互补序列产生逻辑电路,并进行了仿真分析,设计产生了码元长度可变、码元宽度可调的高速率Golay互补序列,同时对应用Golay互补序列的BOTDR传感系统从信噪比、动态范围和测量时间上进行了分析,并对传感系统从时域和频域的角度进行了Matlab仿真,结果表明调制成Golay互补序列的光脉冲较单脉冲传感系统在系统信噪比、温度和应变分辨率等方面能够改善系统的性能。搭建了部分实验系统,完成了基于AOM光脉冲调制的前向光路时域波形测试。 【英文摘要】The research condition of temperature and strain sensing based on Brillouin scattering has been introduced in this thesis. The characteristics and the sensing mechanism of temperature and strain based on Brillouin scattering in optical fiber have been analyzed, and the temperature and strain dependences of Brillouin frequency shift and intensity have been founded. The ratio of the Brillouin scattering light power and Rayleigh scattering light power is used to eliminate the impact of optical loss to compensate the Brillouin scattered light power variation, and to establish the design theory of BOTDR based temperature and strain sensor system using heterodyne detection. Sensing system and signal processing based on heterodyne detection have been studied. The microwave frequency synthesizer in down converter subsystem has been studied in detail. The method of applying Golay complementary sequences in Brillouin sensing system has been used. A high speed Golay complementary code with a variable length and adjustable width is designed based on Max+plus II according to the principle of Golay complementary sequences, and waveform simulation has been done. In the meanwhile, the performance of BOTDR sensing system applying Golay complementary sequences is analyzed from the signal to noise ratio, dynamic range and measurement time of the sensing system. The sensing system has been simulated fro