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针对钢轨探伤可靠性试验及缺陷信号采集处理要求,建立了一套基于激光超声技术的无损检测系统.该系统主要包括高能量脉冲激光器、电磁超声换能器、嵌入式信号采集处理系统以及带有人工缺陷裂缝的P60钢轨试件.在分析利用瑞利波探伤机理的基础上,重点研究了激励线圈阻抗匹配方法,介绍了嵌入式信号采集处理系统工作原理及其信号处理过程.最后利用搭建的激光超声检测系统,实现钢轨表面深度不少于0.5 mm缺陷的定位,并给出了接收信号幅度与提离距离以及缺陷尺寸的关系.“,”To meet reliability of rail steel flaw inspection and signal acquisition, a nondestructive testing (NDT) system based on laser ultrasonic technique (LUT) was established. The system was mainly composed of high energy pulse laser, electromagnetic ultrasonic transducer (EMAT), embedded data acquisition system and P60 rail specimens with artificial cracks. Based on analysis of Rayleigh wave detection principle, this paper focuses on impedance matching method of EMAT probe coil. Besides, working flow path and signal processing of embedded signal acquisition system were introduced. Moreover , system based LUT was used to locate the rail steel surface crack with depth no less than 0.5 mm. Finally, relationship between EMAT probe lift-off distance and signal amplitude was given.