偏振正交双频DBR腐蚀声发射传感器研究

Study on corrosion acoustic emission sensor based on orthogonally polarized dual-frequency DBR laser

为了实现基于光纤传感器的金属腐蚀在线监测,以金属Q235腐蚀声发射在线监测为目标,采用分布式布喇格反射(DBR)光纤激光器作为腐蚀声发射传感器的方法,通过对偏振正交DBR光纤激光器的工作机理及模型进行研究,分析了偏振正交双频DBR激光器用于腐蚀声发射传感器的谐振腔参量对其性能影响的规律,并进行了基于偏振正交双频DBR激光器的声发射检测实验,实现了偏振正交DBR光纤激光器的优化设计,提出了表征Q235碳钢腐蚀阶段的特征量。结果表明,偏振正交DBR光纤激光器不仅能实现对金属腐蚀声信号的检测,其检测频带范围为0MHz^1MHz,还能实现通过平均拍频值的变化来表征金属腐蚀主要的3个腐蚀阶段。该研究为偏振正交DBR腐蚀声发射传感器及组网的优化设计与制作提供了理论和技术基础,对金属腐蚀特别是核级关键材料的在线腐蚀监测具有重要意义。

In order to realize on-line monitoring of metal corrosion based on optical fiber sensors,a distributed Bragg reflection( DBR) fiber laser was used as the corrosion acoustic emission sensor,aiming at on-line monitoring of metal Q235 corrosion acoustic emission. The working mechanism and model of polarized orthogonal DBR fiber laser were studied,and the influence of resonator parameters of polarized orthogonal dual-frequency DBR laser as corrosion acoustic emission sensor on the performance was analyzed. The acoustic emission detection experiment based on polarized orthogonal dual-frequency DBR laser was carried out. The optimum design of polarized orthogonal DBR fiber laser was experimentally studied,and the characteristics of the corrosion stage of Q235 carbon steel were presented. The results show that polarized orthogonal DBR fiber laser can not only detect metal corrosion acoustic signal,but also characterize three major corrosion phases of metal corrosion by the variation of the average beat frequency values with the detection frequency range of 0 MHz ~ 1 MHz. The research project provides the theoretical and technical basis for the optimization design and fabrication of polarized orthogonal DBR corrosion acoustic emission sensors and networks. It is of great significance on on-line corrosion monitoring of metal corrosion,especially nuclear grade key materials.