基于OpenCV视觉库的ESPI图像增强技术研究

针对ESPI条纹图像富含散斑噪声的特点,提出了一种有效的ESPI图像增强技术.阐述了ESPI测量的原理,基于OpenCV开源计算机视觉库,采用偏微分方程的图像滤波方法,离散化PM扩散模型进行滤波处理,并使用灰度直方图均衡化方法提高ESPI条纹图像对比度,最终得到利于相位计算的清晰ESPI条纹图像.提出采用保真度与对比度对ESPI条纹图像增强的量化评估方法,原理分析和实验表明该方法有效降低散斑噪声并保留条纹的边缘信息,提高散斑图像的对比度,具有较强的实用性.     

An electro-optic holography system with real-time arithmetic processing

This paper reports the use of a real-time arithmetic image processor in an electro-optic holography system. A speckle interferometer is used to combine an image of an object, lit by laser light, with a mutually coherent reference beam. A CCD TV camera detects the interference pattern, and the phase of the reference beam is advanced by 90° between frames. An image is generated from each set of four sequential TV frames by subtracting alternate frames, squaring, and adding the two results. The result is improved picture quality compared with the use of binary pixels and compared with electronic speckle pattern interferometry. Experimental results are shown.     

基于电子散斑干涉技术的圆度误差测量方法

分析现有圆度误差的几种测量方法的优、缺点后,提出一种基于电子散班干涉技术的圆度误差测量与评定的新方法,测量结果表明,新方法简单易行、精确度高,有一定的应用前景。     

激光电子散斑干涉技术在连杆设计中的应用

电子散斑干涉法(ESPI)是计算机图像处理、激光和干涉等新技术的有机结合。这一方法在二维位移场(u场和v场)测量中应用位相技术实现了位移的数字化。详细介绍了ESPI技术在柴油机连杆设计上的应用,获得了连杆模型的两维位移场数据,并和有限元法(FEM)结果进行了比较,两者相吻合。所测得的位移场也可作为有限元计算的边界条件。     

激光干涉在蜂窝夹心层板振动模态测量中的应用

采用激光电子散斑干涉测量技术(electronic speckle pattern interferometry,简称ESPI)对悬臂矩形损伤蜂窝夹心复合板稳态振动下的振型进行了实验研究。通过完整试样的振型测量结果与有限元模拟均匀悬臂金属板结构振型的类比,验证了有关蜂窝夹心复合材料具有横观各向同性假设的观点,获得了悬臂矩形蜂窝夹心复合层板前14阶离面振动模态的振型图。实验结果表明,结构的损伤导致其局部刚度改变,使得共振频率减少,损伤对其高阶振型的形状改变较为明显,有时甚至是模态跃迁。     

Experimental Analysis of Thermo‐mechanical Behaviour of Electronic Components with Speckle Interferometry

Experimental investigations of thermo‐mechanical behaviour of electronic components may help to prevent catastrophic in‐service failures. Non‐contact optical techniques such as speckle and moiré interferometry are naturally suited for carrying out measurements on electronic equipment as they are non‐invasive techniques and provide high‐resolution full‐field information on displacements. In spite of its inherent ability to measure deformations at the nanometer level, there are few examples of application of speckle interferometry to true monitoring of thermo‐mechanical behaviour of electronic components in real time. For this reason, the paper presents a phase shifting electronic speckle pattern interferometry (PSESPI) experimental set‐up developed in order to monitor the time evolution of thermal deformations in electronic components for aerospace applications submitted to normal or anomalous working conditions. Cyclic loads are also analysed to assess fatigue behaviour. Experimental results obtained for whole electronic boards and single components mounted on board fully demonstrate the capability of PSESPI to detect even small differences in thermo‐mechanical response between normal and anomalous functioning.     

Experimental and numerical investigations for the free vibration of cantilever trapezoidal plates

Abstract

Based on the advantages of non‐contact and full field measurement, the optical technique called amplitude‐fluctuation electronic speckle pattern interferometry (AFESPI) with an out‐of‐plane setup is employed to investigate the free vibration of cantilever trapezoidal plates with various taper ratios and sweep‐back angles. Twenty different plate configurations are analyzed, including triangular and trapezoidal plates, and the first seven vibration modes of each plate are measured. The AF‐ESPI method is very convenient for measuring vibrating objects because no contact is required in contrast to classical modal analysis using accelerometers. Based on the fact that clear fringe patterns will appear only in resonance, both resonant frequencies and corresponding mode shapes can be obtained experimentally using the present technique. Numerical calculations by finite element method are also performed and the results are compared with the experimental measurements. Excellent agreements are obtained for both results of resonant frequencies and mode shapes. The influences of taper ratios and sweep‐back angles on the vibration behavior of cantilever trapezoidal plates are also demonstrated in terms of the dimensionless frequency parameter.     

电子散斑干涉中相移技术研究

本文介绍了电子散斑干涉（ESPT）原理、相移技术方法。针对散斑条纹图中高频项对于相位计算的干扰,对相移算法提出了2种修正的方法。对简支梁进行了位移场的测量,并与有限元（FEM）计算结果进行对比,证明了改进的相移技术在ESPI中是可靠的。     

Experimental analysis of vibration characteristics of an edge- cracked composite plate by ESPI method

In this paper, the amplitude fluctuation (AF) electronic speckle pattern interferometry (ESPI) method was adopted to investigate the vibration characteristics of a composite plate containing an edge crack. The change of the modal shapes was discussed. In addition, the stress intensity factors (SIFs) induced by the resonant vibration were evaluated. This revised version was published online in August 2006 with corrections to the Cover Date.     

激光测振技术的最新进展

激光测振技术在近20年取得了巨大进展。本文以2004年6月在意大利召开的第六届激光测振国际会议的技术内容为基础，重点介绍激光测振技术在计量学方面的进展和在其他领域的应用。