基于相干探测的激光超声检测系统设计与实现

Design and implementation of laser ultrasonic testing system based on coherent detection

提出一种基于激光注入光纤相干的材料表面缺陷无损检测系统,将光学传感、空间光耦合及平衡探测技术有机结合,利用脉冲激光激励与单频激光探测手段,探讨激光超声信号在介质中的产生、传播与检测机理,并通过数据采集与Lab VIEW图形化编程设计的上位机界面,对信号特性进行分析和处理。实验测试表明,采用激光注入光纤相干探测系统的信号检测,能减小系统噪声的影响,降低输出信号抖动,通过超声回波峰值信号突变,有效实现工件缺陷判断,为工程应用提供一种新的测量方法。

A non-destructive testing system of surface defects based on laser injection is put forward. The optical sensorand spatial optical coupling combined with balanced detection technique, and the generation, propagation and detectionmechanism of laser ultrasonic signal in medium are discussed by using pulsed laser excitation and single frequency la-ser detection, and by means of data acquisition and LabVIEW graphical programming design of the host computer in-terface, the signal characteristics are analyzed and processed. Experimental results indicate that signal detection of fi-ber coherent detection system based on laser injection can reduce the influence of system noise and reduce output sig-nal jitter. Then workpiece defect judgment can effectively achieved through the ultrasonic echo peak signal mutation,and it can provide a new measurement method for engineering applications.