时间序列散斑干涉技术的发展及应用

当用相干光照射一个连续变形的漫射物体表达时，由漫射物体表面散射所形成的物光与一参考光干涉，在其干涉的区域即可形成一随时间变化的散斑场，连续采集这一时变散斑场，并通过时间域分析，即可获得被测物质表面所对应的时变位移场，本文在作者研究的基础上，介绍序列散斑计量技术中所发展起来的几种计量方法，探讨它们的计量特性及其发展方向，并同时给出这些计量方法在时变场检测中的一些应用成果。     

Nondestructive testing using temporal phase evaluation in speckle interferometry

A novel nondestructive testing (NDT) method is reported in which temporal evolution of the speckles in speckle interferometry is used to measure large object deformations. The basic principle of the method is that continuous object movement introduces fluctuations in the phase of the speckle and is recorded as intensity modulation. Acquiring a large number of frames of the object motion, the phase data for the whole object deformation are then retrieved by the Fourier transformation technique. The method is capable of measuring more than 100 μm in-plane and out-of-plane deformation with speckle interferometry and more than 500 μm for speckle shearing interferometry. The authors discuss the NDT results obtained with the three methods and make some relative comparisons of each.     

Impact-induced transient deformation analysis by means of digital speckle pattern interferometry

Transient in-plane displacements generated in a metal plate subjected to impact loading are measured using a pulsed digital speckle pattern interferometry system. Two separated speckle patterns produced by a ruby laser that freezes the object motion are recorded using a CCD camera and stored in a frame grabber. Transient displacements are evaluated by digital analysis of the fringes generated by the subtraction of these speckle patterns. The computer used for image processing is also utilized to control image acquisition and to synchronize the laser pulses to the CCD camera and the object position. Experimental results are compared with numerical calculations obtained using the finite-element method.     

Residual Stress Determination by Hole Drilling Combined with Optical Methods

An overview is provided of the use of eight different optical methods with hole drilling to determine residual stresses. The methods considered are: brittle and photoelastic coatings, Moire interferometry, holographic interferometry, electronic speckle pattern interferometry, interferometric strain rosette, digital image correlation and shearography. A number of applications are summarized, such as the use of hole drilling with holographic interferometry to investigate stresses in rock structures accessed by deep boreholes and to determine manufacturing-induced residual stresses in fillets of small radii.     

Full-field calculation of hole drilling residual stresses from electronic speckle pattern interferometry data

A mathematical method is proposed for calculating residual stresses from hole drilling electronic speckle pattern interferometry (ESPI) data, independent of rigid-body motions. Even though the signal-to-noise ratio of typical ESPI data is modest, the method achieves good computational stability by averaging a large amount of data. It does this without excessive numerical effort by exploiting known trigonometric relationships among the data. The resulting stress calculations are very rapid, and are well suited for future application to non-uniform stress measurements.     

多相机3D-DIC及其在高温变形测量中的应用

将基于双目视觉的三维数字图像相关方法 (Three-dimension digital image correlation,3D-DIC)与多相机同步采集系统相结合,形成基于多相机的3D-DIC系统。依据三维空间误差(Three-dimensional residual,3Dresidual)最小原则,确定各点对应的最佳双目视觉系统,获得物体全场三维变形。以四相机3D-DIC系统为例,与测量精度达10~20nm的电子散斑干涉测量系统同时对平板的离面位移进行测量,并对测量得到的离面位移最大值进行了对比分析。结果显示,荷载较小时,四相机3D-DIC与电子散斑干涉测量系统误差稍大,最大达到2.7%;荷载增大,物体变形增大时,两种测量系统结果基本相同。文中讨论了四相机测量系统的不稳定对实验结果的影响。利用该四相机3D-DIC系统对镍合金不锈钢材料在高温场中的变形进行测量,获得了物体的三维变形场,并分析了材料的膨胀系数,得到了试件的热应变-温度曲线和膨胀系数随温度变化的关系式。     

DIC-Based Surface Motion Correction for ESPI Measurements

Electronic Speckle Pattern Interferometry (ESPI) provides a sensitive technique for measuring surface deformations. The technique involves comparison of the speckle phase angles within surface images measured before and after material deformation. This phase angle comparison requires that the speckle positions be consistent in all images. A lateral shift between image sets of just one pixel substantially degrades ESPI measurements, while a shift of two or more pixels typically causes complete decorrelation and compromises the measurement entirely. To prevent such rigid body motions, the specimen and the optical system must be rigidly fixed. This requirement typically impedes use of the ESPI method in applications outside laboratories or where it is necessary to remove the specimen from the optical setup between ESPI measurements. Here, Digital Image Correlation (DIC) is used to track speckle motion caused by specimen displacement between ESPI phase stepped image sets. The measured image set can then be mathematically shifted to restore the original speckle locations, thereby recorrelating the ESPI measurement. Examples are presented where ESPI measurements are successfully made with specimen shifts over 60 pixels.     

数字散斑剪切干涉及偏转平台法相移系统研究

在传统的剪切电子散斑干涉中 ,直接观测到的是干涉条纹图样。因此 ,如何将位移导数场的定量信息从剪切电子散斑干涉条纹图案中提取出来 ,一直是人们关心的问题。本文运用传播光矢量对数字散斑剪切干涉的条纹形成作了理论解释 ,使其物理意义更加清晰。理论分析表明 ,物体的微小偏转可引入线性附加位相。因此 ,通过连续偏转物体可实现剪切电子散斑干涉的相移。本研究通过计算机控制载物平台的精细旋转实现相移 ,结合传统的数字散斑剪切干涉技术以及四步相移算法 ,实现了数字剪切散斑干涉相移系统。利用该系统进行了中心加载、周边固定的圆盘的典型实验 ,实验结果表明该系统可以方便有效地提取出位移导数场的定量信息。     

电子剪切散斑在检测材料缺陷中的应用

随着电子技术、计算机技术的飞速发展,传统的全息干涉技术已经发展到了电子散斑和电子剪切散斑阶段。电子散斑和电子剪切散斑不仅可以完成表面变形量的测量,并且由于它们具有实时性、高灵敏度、非接触性和全场测量等优点,在工业和科研领域中得到了越来越广泛的应用。本文首先介绍了电子剪切散斑干涉的基本原理,然后着重介绍了自行编制的对离面位移的电子剪切散斑图像进行处理的系统。该图像处理系统的主要功能有平滑、区域标记、像素统计等。用该系统对图像进行处理后,可以直接得到缺陷的实际大小。通过对带有已知缺陷模型的实际测量,所得结果与实际吻合较好,说明该图像处理系统是可行的。     

Measurement of slopes of structural deflections by speckle-shearing interferometry

A specimen illuminated by coherent light is imaged by a camera through a shearing mechanism so that the speckle from one point on the surface can be made to interfere with the speckle from a neighboring point. The resultant speckle pattern is recorded. By mechanically interfering the recorded speckle pattern corresponding to deformed and undeformed states of the specimen, respectively, using double-exposure technique, a speckle-moiré-fringe pattern is generated. These fringes which depict derivatives of deflections of the specimen are made visible by spatial-filtering technique. Speckle-moiré fringes can also be obtained in real time. This method is a new interferometry and will be referred to as “speckle-shearing interferometry”. Speckle-shearing interferometry has the same function as Ligtenberg's technique. However, it does not have the sometimes inconvenient requirement of Ligtenberg's technique that the surface of the specimen must be of mirror quality. The new technique will be particularly useful in studies of flexural deformation such as flexed beams and plates. Although speckle-shearing interferometry is an interferometric method, it overcomes several of the limitations associated with holographic and speckle interferometries, namely: (1) the setup is simple and does not need laborious alignments of optical components, (2) it does not require stringent mechanical and ambient stabilities, (3) coherent requirement of light is greatly relaxed, and (4) the sensitivity is reduced that somehow fills the gap in sensitivity between moiré techniques and holographic or speckle interferometry.     

光栅大错位数字散斑干涉系统及其应用研究

本文用统计光学理论简要简述了大错位数字散斑干涉的原理及特点,并在此基础上首次提出利用光栅作为错位元件的光栅大错位数字散斑干涉。该方法具有与全息干涉计算相同的灵敏度,光路简单、结构紧凑,波像差小,防震要求低等特点,文中对该方程进行了详细的原理分析与介绍,利用其对典型试件受均布载荷下的离面位移场进行测量,通过理论值与实验结果的比较,表明该方法的可行性,该方法拓宽了散班干涉技术的适用范围,为实际生产中的     

利用光学干涉条纹图相位分析测量纳米位移

Optical methods such as Twyman-Green interferometry, moiré interferometry, holographic interferometry and speckle interferometry are useful to measure displacement and strain in the full-field of structures. Recently phase analysis method of fringe patterns obtained by these optical methods becomes popular, and it provides accurate quantitative results in the full-field. In this paper, in order to measure displacement and strain, real-time or high-speed nano-meter displacement measurement methods developed by the authors are introduced. That is, (1) out-of-plane displacement analysis by Twyman-Green interferometry using integrated phase-shifting method using Fourier transform phase-shifting method, (2) simultaneous two-dimensional in-plane displacement analysis by moiré interferometry and (3) out-of-plane displacement analysis by phase-shifting digital holographic interferometry. The theories and applications are shown.     

光导纤维在近代光力学中应用的综述

本文综述了国内外光导纤维在全息干涉、散斑计量及云纹法中应用的历史和现状。光纤不仅可以作为柔性传光元件应用于近代光测力学,还可以用多模传象束传送物光波前,从而使得测量远方的或特殊环境下构件的位移场、应变场成为可能。     

Nano-meter Displacement Measurement by Phase Analysis of Fringe Patterns Obtained by Optical Methods

0Introduction Inordertomonitorthehealthofstructures,straingagesanddisplacementtransducersare usuallyused.Thereasonisthatmanyrulesorcodesforinspectionofstructuresrequiretousestrain gagesanddisplacementtransducers,anditiseasytousethem.However,thesemethodsarebasically one pointmeasurementmethods.Theyareexpensiveandtime consumingfordistributionanalysis.Opticalmethodssuchasgrating projection,geometricmoir啨,moir啨interferometry,holographic interferometryandspeckleinterferometryareusefultomeasuredi…     

Enhancing sensitivity of the white-light speckle method in terrestrial applications

Noncoherent-light speckle interferometry techniques have been used for terrestrial motion measurements. The long imaging distances typical of these applications limit sensitivity and accuracy because of atmospheric turbidity. Experiments show that the performance of camera systems used to record glacier surface speckle agrees with the predictions of theory developed for astronomical work. Several methods to enhance the technique are suggested.     

用电子散斑干涉法进行结构内部微小缺陷检测的研究

本文应用电子散斑干涉法和相移技术对结构内部缺陷测试进行了试验研究,研究中采用气压加载,获得了相同气压载荷作用下不同试件的变形图,由此计算得到的结果表明,有缺陷的试件和无缺陷的试件在相同的气压载荷作用下变形不同,同时,相同载荷作用下,缺陷尺寸不同时,试件的变形不同.该试验证明了电子散斑干涉法在研究结构内部缺陷在气压载荷作用下的微小变形的有效性,进一步对缺陷影响的定量研究将为预知缺陷的尺寸及位置,结构的安全和检测提供帮助,同时将该方法应用进一步的推广和改进,将为结构无损检测提供依据.     

Static and Modal Analysis of Low Porosity Thin Metallic Auxetic Structures Using Speckle Interferometry and Digital Image Correlation

This study presents an evaluation of the static and dynamic mechanical behavior of low porosity, ductile two-dimensional auxetic metamaterials. The full in-plane displacement fields and the eigenmodes of different geometric structures were investigated and compared with finite element simulations using speckle interferometry and digital image correlation. The results showed strong agreement, validating the theoretical approach used and establishing a method for testing and quantitatively assessing the performance of negative Poisson ratio structures, and metamaterials in general, for different purposes and fields. The findings of this study also increase our knowledge of elastic instabilities in metallic auxetic structures, with further applications in several engineering fields that can benefit from combining the qualities of ductile materials with additional features typical of these smart structures.     

撞击载荷下数字散斑干涉法中位相的自动计量

在撞击载荷下的数字散斑干涉法（DSPI）中，本文联合应用加法和减法两种模式提出了位相测试技术，以矩形板对称轴承受撞击集中载荷为例，测量了位移场的位相分布，为了采集红宝石脉冲激光形成的数字散斑场，提出瞬态数字图像采集技术。     

数字图像相关方法中散斑图的质量评价研究

在利用数字图像相关方法测量物体表面变形时,被测物体表面必需覆盖有灰度随机分布的散斑场,该散斑场作为试件表面变形信息的载体随试件一起变形。在实际情况下,不同的散斑场会显示出完全不同的灰度分布特征,并对数字图像相关方法的测量结果有着重要影响。因此如何定量评价散斑图的优劣是数字图像相关方法中一个重要的基本问题,也是该方法的使用者非常关心的问题。基于最近数字图像相关方法基本理论研究的进展,本文提出平均灰度梯度这一新参数用于散斑图质量的评价。为证实该参数的有效性,本文对五幅明显不同的散斑图进行了精确平移,并将数字图像相关方法测量的位移与预加的平移量进行比较,分析了位移测量结果的均值误差和标准差。结果显示位移测量结果的均值误差和标准差均与散斑图的平均灰度梯度有关,一个好的散斑图应该具有较大的平均灰度梯度。     

热毛细对流温度场ESPI检测研究

在地面上用二维液体盒研究了热壁下气泡周围液体中的热毛细对流现象,并应用电子散斑干涉技术（ESP）对热毛细对流温度场进行了实时检测研究,给出了部分典型的实验结果。