板状材料激光超声CT成像的研究

1引言激光超声技术[1]是指由一束激光来检测另一束激光激发超声的技术,其较传统用压电换能器的超声检测有以下优点:高的空间和时间分辨率,高的灵敏度,非常适合在线非接触检测。目前激光超声检测技术不仅是声传播基础研究的重要实验手段,而     

金属表面裂纹脉冲压缩增强型激光超声检测方法研究

为了提高激光超声技术检测能力,提出了一种基于脉冲压缩的增强型激光超声检测方法,并将其用于金属表面裂纹检测。该方法结合激光束空间分布调控技术,激发线性调频超声表面波信号,进一步利用匹配滤波算法对线性调频激光超声表面波信号进行脉冲压缩,可大幅度提高激光超声检测信号的信噪比和分辨率。建立空间调制激光超声数值计算模型,研究线性调频激光超声信号激励方法;基于数值模拟获得的线性调频激光超声检测信号,开发基于匹配滤波器的激光超声脉冲压缩信号处理方法;通过数值模拟不同表面裂纹缺陷与不同空间调制情况下的脉冲压缩信号效果,探究该方法对于激光超声检测信号信噪比的增强能力,并最终通过试验验证。结论表明,基于脉冲压缩技术的增强型激光超声检测方法,可以大幅度抑制噪声信号,提高针对金属表面裂纹的缺陷检测能力,解决激光超声无损检测信噪比低,灵敏度差的问题,也为该方法进一步研究提供理论依据和试验指导。     

基于LabVIEW的激光超声管道检测系统

油气管道在日常生活和经济建设中发挥着重要作用,同时也存在着安全隐患,各种油气管道爆炸事件时有发生,给人们的生活和财产带来威胁。为保证油气管道的安全有效运行,应定期对其进行检测。激光超声检测技术相对于传统超声检测技术具有更高的空间分辨率,这一优点使其具有检测油气管道微小缺陷的潜力。该文根据激光超声检测原理,设计基于LabVIEW的激光超声燃气管道检测系统,重点介绍系统中数据采集、运动控制和数据分析模块,解决从激光超声信号的激励到数据采集、信号分析处理和缺陷识别等技术问题,实现油气管道各类缺陷的快速检测的目的。通过对带有周向裂纹管道做检测实验,结果表明:该系统具有良好的检测性能,对解决激光超声测量与诊断问题具有实际意义。     

动态与信息

第七届全国激光检测与应用技术交流会在屯溪召开中国光学学会和中国航空学会于1994年8月16日至20日在安徽省屯溪市召开了第七届全国激光检测与应用技术交流会。来自12个省市自治区的64位代表参加了会议。会议共收到征文67篇，其中54篇论文（摘要）收入本届会议论文集。30位代表在大会上宣讲了35篇论文，分别涉及激光全息无损检测及干涉计量，激光散斑无损检测及干涉计量，激光光纤检测技术及应用，激光尺寸、形状、位置测量技术，激光多普勒测量技术，激光参数测量技术，激光在线检测技术，激光显示技术，激光超声检测新技术，激光光谱等方…     

基于空耦换能器的碳纤维增强环氧树脂编织复合材料激光超声检测技术

激光超声技术具有无需耦合剂、快速及高分辨等特点,适用于各向异性碳纤维增强树脂编织复合材料的缺陷检测。运用有限元法分析了激励位置和编织结构对激光点源激发超声波信号的影响,获得了弹性波在材料内部的传播规律以及能量分布特征,并采用1 MHz空气耦合换能器搭建了一套小型化、低成本的非接触激光超声C扫描成像系统,开展了斜纹和缎纹碳纤维增强树脂编织复合材料的近表微结构和内部缺陷检测实验。结果表明,基于空气耦合换能器的激光超声成像可以高精度地再现碳纤维增强树脂编织复合材料的近表树脂囊、碳纤维束形状、取向、尺寸及其内部缺陷等空间分布特征,有望为航空复合材料提供一种原位的微结构表征和缺陷检测方法。      

基于激光超声的金属构件表面微裂纹定量检测技术研究

传统超声无损检测技术一般需对比裂纹构件与无损构件响应数据,分析两者差异以识别裂纹;两次测量结果易受人工操作误差、外界环境变化影响,导致裂纹误检。针对该问题,提出一种基于激光超声的金属构件表面微裂纹定量检测技术,该技术通过提取激光超声波与裂纹构件作用后非线性特征参数改变量实现裂纹定量检测,无需参考无损构件响应数据,能有效减少因人工操作误差、外界环境变化引发的裂纹误检;利用激光辐照构件激发超声波,根据构件时域动态响应信号重构相空间,引入一种非线性特征参数提取方法对构件上相邻辐射点之间状态空间改变量进行评估以实现裂纹检测。构建实验系统对空压机缸体表面实际砂孔缺陷及疲劳裂纹进行检测,结果表明所提技术能有效定量检测金属构件表面微裂纹。     

激光技术在出入境证件防伪中的应用

自世界上第一台激光器于1960年诞生以来,激光技术发展迅猛。40多年来,激光技术与多个学科相结合广泛应用于相关技术领域,比如光电技术,激光医疗与光子生物学,激光加工技术,激光检测与计量技术,激光全息技术,激光光谱分析技术,激光雷达,激光制导,激光分离同位素,激光可控核聚变,激光武器等等。这些交叉技术与新的学科的出现,大大地推动了传统产业和新兴产业的发展。本文主要探讨激光技术在出入境证件防伪中的应用。激光技术应用出入境证件防伪领域,主要包括两个方面:激光打孔与激光全息技术。其中打孔又可分为号码打孔、分布打孔、标识打孔、…     

计量新技术—激光超声

本文介绍了激光激励超声的原理和特性，非接触检测激光超声的方法以及激光超声在计量与检测的应用前景，并报导了作者用Ｑ开关ＹＡＧ激光器在铝、铜和钢中激励的超声脉冲和和压电换能器和外差干涉接收激光脉冲的实验结果。     

水利工程中金属焊缝缺陷的超声检测方法比较研究

为研究基于超声的无损探伤方法在水利工程金属结构焊缝缺陷识别中的应用,利用常规超声检测技术、超声相控阵技术、衍射时差法(Time of Flight Diffraction, TOFD)超声检测技术对水利工程金属结构焊接试块缺陷进行识别,分析了各种缺陷在超声无损探伤技术中的特征显示。研究结果表明:常规超声检测技术、TOFD检测技术均能对各种缺陷实现信号显示,超声相控阵检测技术对气孔和横向裂纹的显示不够明显,但对其它缺陷的检出效果较为明显;常规超声检测技术对操作人员的要求较高,对缺陷的定性困难,精度不高;TOFD检测结果中气孔和横向裂纹的显示呈现出一种特殊的弧形,有一定高度的内部裂纹和未熔合的信号由上下尖端衍射波组成,根部未焊透上下尖端信号不够明显;相控阵检测结果直观,可以较精确地测量缺陷的埋藏深度、自身高度、长度等,但在扫查点状缺陷或者与超声声束平行的裂纹缺陷时,检出率极低。     

激光超声的基本理论实验和应用

采用压电换能器的超声探伤技术，是沿用已久并为大家普遍接受的一种有效的无损检测方法，而且它具有一系列优点，如价格低廉、结构简单、使用方便。它的使用是如此广泛和成功，以至自它问世几十年来，几乎没有任何竞争对手可以取代它。既然如此，人们不禁要问：为什么当今世界大部分先进国家的无损检测业都在倾注全力竞相研制复杂昂贵的激光超声系统？通过本文，我们将就激光超声的基本理论、实验和应用前景作一全面的论述。     

2006 Distinguished Service Award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Gerry V. Blessing

The recipient of the 2006 Distinguished Service Award of the Ultrasonics, Ferroelectrics, and Frequency Control Society is Dr. Gerald V. Blessing, "for over twenty-five years of leadership and commitment in a wide range of positions including Officer in the local chapter, organizer of Ultrasonics Symposia, and President of the IEEE UFFC Society."     

2007 Outstanding Paper Award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society

The Administrative Committee of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society takes great pleasure in announcing the selection of the Outstanding Paper published in its 2007 Transactions, vol. 54. The award was presented during ceremonies at the 2008 IEEE International Ultrasonics Symposium in Beijing, China, on November 3rd, 2008. The award winner is Clark T.-C. Nguyen for his paper "MEMS Technology for Timing and Frequency Control." This paper appeared in the February 2007 issue, no. 2, on pages 251-270. Award Committee members selected this paper among all others that appeared in vol. 54 of the IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control.     

2008 Achievement Award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Mack Breazeale

Professor Mack A. Breazeale is the 30th recipient of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Achievement Award. The award was presented during ceremonies at the 2008 IEEE International Ultrasonics Symposium in Beijing, China, on November 3rd, 2008. The laudation was presented by Professor James G. Miller (Washington University, St. Louis, MO). Prof. Breazales's award citation reads: "For a five-decade-long career of major contributions to non-linear ultrasonics."     

2008 Rayleigh Award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society William D. O'Brien, Jr.

Professor William D. O'Brien, Jr. is the 8th recipient of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Rayleigh Award. The award was presented during the ceremonies at the 2008 IEEE International Ultrasonics Symposium in Beijing, China, on November 3rd, 2008. The laudation was presented by Prof. Kirk Shung (University of Southern California, Los Angeles, CA). Professor O'Brien's award citation reads: "For pioneering contributions in acoustics and medical diagnostics research and education and for devoted service to the IEEE UFFC Society."     

2007 Rayleigh award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Arthur Ballato

Dr. Arthur Ballato is the recipient of the 2007 Rayleigh Award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society.     

2007 Distinguished service award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society James F. Greenleaf

Professor James F. Greenleaf is the recipient of the 2007 Distinguished Service Award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society.     

2007 Achievement award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Matthew O'Donnell

Professor Matthew O'Donnell is the recipient of the 2007 Achievement Award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society.     

Information for contributors with multimedia addition - table of contents

The scope of interest of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control (UFFC) Society shall include theory, technology, materials, and applications relating to: (1) the generation, transmission, and detection of mechanical waves and vibrations and their interactions with other phenomena; (2) medical ultrasound, including hyperthermia, bioeffects, tissue characterization and imaging; (3) ferroelectric, piezoelectric, and piezomagnetic materials, including crystals, polycrystalline solids, films, polymers, and composites; (4) frequency control, timing and time distribution, including crystal oscillators and other means of classical frequency control, and atomic, molecular and laser frequency control standards. Areas of interest range from fundamental studies to the design and/or applications of devices and systems.     

Information for contributors with multimedia addition

The scope of interest of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control (UFFC) Society shall include theory, technology, materials, and applications relating to: (1) the generation, transmission, and detection of mechanical waves and vibrations and their interactions with other phenomena; (2) medical ultrasound, including hyperthermia, bioeffects, tissue characterization and imaging; (3) ferroelectric, piezoelectric, and piezomagnetic materials, including crystals, polycrystalline solids, films, polymers, and composites; (4) frequency control, timing and time distribution, including crystal oscillators and other means of classical frequency control, and atomic, molecular and laser frequency control standards. Areas of interest range from fundamental studies to the design and/or applications of devices and systems.     

2006 Outstanding paper award of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society

Presents the recipients of the 2006 Outstanding Paper Awards of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society.