基于压缩感知的快速激光超声合成孔径聚焦技术  

Fast Laser Ultrasonic Synthetic Aperture Focusing Technology Based on Compressed Sensing

作　　者：何志同 应恺宁 戴鹭楠 倪辰荫[1] He Zhitong;Ying Kaining;Dai Lunan;Ni Chenyin(School of Electronic Engineering and Optoelectronic Technology,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China;College of Science,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China)

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094 [2]南京理工大学理学院,江苏南京210094

出　　处：《中国激光》2024年第2期28-38,共11页Chinese Journal of Lasers

摘　　要：传统激光超声合成孔径聚焦技术(LU-SAFT)通常需要在待测样品表面以小步长扫描来提高横向分辨率,但小扫描步长会导致总检测时间过长,影响检测效率。针对这一问题,笔者提出了基于压缩感知的LU-SAFT方法,以提升扫描效率。该方法首先使用压缩感知根据稀疏扫描点处A扫信号的最大强度恢复出全场的扫描点A扫信号最大强度,进而确定样品表面的最优扫描区域,然后在最优扫描区域内进行扫描,最后对缺陷进行SAFT图像重建。在实验中,笔者采用脉冲激光在含有缺陷的样品表面激发超声,使用激光多普勒测振仪探测超声,并利用基于压缩感知的LU-SAFT方法对样品内部缺陷进行检测,以验证所提方法的可行性。实验结果显示:针对相同的扫描区域,传统LU-SAFT需要扫查500个点,花费3.15 min;与传统LU-SAFT相比,本文所提方法在扫描点数上减少了80%,在扫描时间上缩短了80%,并且缺陷的SAFT成像信噪比提高了约42%。本文研究内容及结果可为激光超声无损检测提供更快速的检测方案。Objective In the industrial sector,the processing or extended utilization of various metal workpieces can generate assorted surface and internal defects.These imperfections can compromise the mechanical strength of the workpiece,thereby reducing its operational lifespan.Given its high penetration capacity and sensitivity,ultrasonic inspection has gained widespread usage in defect detection.In recent years,there has been an increased focus on imaging technologies in the evolution of defect detection methods.Among these,the synthetic aperture focusing technique(SAFT)is a viable imaging algorithm for ultrasonic inspections.It replaces large-aperture sensors with a series of individual small-aperture sensors,thereby enhancing the lateral resolution.The laser ultrasound synthetic aperture focusing technology(LU-SAFT)is a fusion of SAFT and laser ultrasound technologies,reaping the benefits of both.However,conventional LU-SAFT typically requires small-step scanning of the sample surface to be tested to enhance lateral resolution.This methodology,while effective,results in a prolonged overall detection time,thereby reducing the efficiency of the detection process.This major limitation hinders the practicality of traditional LU-SAFT.In our study,we aim to enhance the scanning efficiency and reduce the scanning duration of the conventional LU-SAFT.Methods This study presented a LU-SAFT method based on compressed sensing to enhance the scanning efficiency of conventional LU-SAFT.Initially,compressed sensing was employed to retrieve the maximum intensity of the A-scanning signal at the scanning points of the entire field from the maximum intensity of the A-scanning signal at sparse scanning points.Following that,the optimal scanning area of the sample surface was determined.Subsequently,scanning was conducted in this optimal area.Finally,SAFT image reconstruction was conducted for the defect.In the experiment,a pulsed laser was utilized to incite ultrasound on the surface of a defective sample.A laser Doppler vibrometer was

关 键 词：激光光学 压缩感知 合成孔径聚焦技术 激光超声 缺陷检测 

分 类 号：TG115.28[金属学及工艺—物理冶金]