共查询到16条相似文献,搜索用时 234 毫秒
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用激光光束直接照射到测试表面,再用CCD采其变形前后表面散斑颗粒干涉形成的条纹,条纹图解析为测量点的位移量和变形量,进而得到其离面位移,在优化算法的时候采用π位相技术获取另一个π相移的变形条纹图像,将面内位移与离面位移分离,为了消除零级分量,让投影光栅移动1/2个周期.通过Matlab和四步位相算法给出了三维空间模型,得出变形后物体的离面位移数据.实验仿真数据表明其能够稳定地测量物体变形场三维分量,误差较低. 相似文献
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设计了基于光学涡旋相移技术的离面位移测量实验方案,实现了电子散斑干涉中相移的数字控制.该方法利用输入液晶空间光调制器中的叉形光栅产生涡旋光束,通过涡旋光束绕轴的旋转产生相移;同时,产生的涡旋光束又作为参考光与物光干涉.实验中,在物体发生离面位移前后依次输入四幅叉形光栅,产生相移步长为π/2的涡旋光束,利用CCD获得涡旋光与物光的干涉光场,从而获得离面位移场的包裹相位;再通过解包裹,获得物体离面变形的相位变化.光学涡旋相移法可应用于离面位移测量. 相似文献
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将涡旋光应用于电子散斑干涉,测量变形物体的离面位移.把传统的电子散斑干涉测量技术与液晶空间光调制器相结合,将所获得的涡旋光作为参考光或者物光进行变形测量.推导出物光为平面光、参考光为涡旋光,和参考光、物光均为涡旋光时物体变形后的干涉强度公式,模拟计算了变形后的干涉图样,分析了变形图样的特征.运用四步相移方法得到了物体的变形相位公式,通过解包裹得到了物体的变形相位.模拟计算得到的三维相位分布图与物体离面位移的变形相位理论值的三维分布图相吻合.模拟实验结果表明,涡旋光可以应用于物体的变形测量,为变形测量提供新的途径. 相似文献
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基于数字图像相关的三维刚体位移测量方法 总被引:7,自引:0,他引:7
基于三维位移测量在工程技术领域的必要性和重要性,开展了单摄像机和数字图像相关相结合的三维刚体位移测试方法的研究.基于图像位移场矢量中心和斜率与面内和离面位移的分别对应关系,采用最小二乘拟合法分离图像位移场的常量项与一次项,据此,可实现物体三维位移分量的有效分离.以针孔摄像机成像模型为基础,开展了数值模拟及硅片平移实验,发展了与三维刚体位移对应的散斑图模拟方法,验证了基于仿射变换的相关迭代法的精度和适用性.数值模拟与实验结果验证了数字图像相关方法用于实现物体三维刚体化移重构的可行性和优越性,最大测量误差为5%. 相似文献
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基于三维位移测量手段在工程技术领域的必要性和重要性,开展了基于单摄像机和数字图像相关的三维位移测试方法研究.基于图像位移场矢量中心和斜率与面内和离面位移的分别对应关系,采用Savitzky-Golay(SG)微分滤波器分离图像位移子区内的常数项与一次项,可实现物体三维位移分量的有效分离.以针孔摄像机成像模型为基础,开展了相应的数值模拟实验及悬臂梁端部受载的实验,发展了与三维线性变形对应的散斑图模拟方法,验证了基于二阶位移模式的牛顿-拉夫森迭代法的精度和适用性.数值模拟与实验结果均验证了三维位移测试方法用于实现物体三维位移重构的可行性和优越性. 相似文献
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针对一套数字全息装置只能测量离面位移这一个维度位移的局限性问题,将数字全息与数字图像相关方法相结合,利用数字全息重建的强度图像,实现了面内另外两个维度位移的测量,拓宽了一套数字全息装置的测量能力.该方法对待测物体位移前后的全息图数值重建得到两幅强度图,然后对变形前后的强度图应用数字图像相关方法得到面内两个维度位移的测量... 相似文献
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Amalia Martínez Ramn Rodríguez-Vera J. A. Rayas H. J. Puga 《Optics and Lasers in Engineering》2003,39(5-6):525-536
Optical interferometry techniques have been used for high-precision displacement measuring. Commonly, in-plane sensitive arrangements use two symmetrical collimated wavefronts for object surface illumination. However, this is a limitation when large object surface, has to be analyzed. In this case spherical illumination is needed. As a consequence of using non-collimated symmetrical dual-beams the sensitivity vector varies with the local position on the surface target. Then, this kind of illumination is also capable of detecting a lightly and systematic out-of-plane component of deformation. In this paper a theoretical analysis of the sensitivity vector components behavior is made. Each component of the sensitivity vector to minimize the required displacement component uncertainty is calculated. This study is important in the stage of planning any interferometric measurement experiment, particularly, for moiré grating interferometric technique, which has been used only in collimated illumination. By using a spherical dual-beam optical setup, the present work shows results of fracture measuring by using moiré and speckle interferometric methods. As a result, advantages and disadvantages of both techniques are discussed and an accuracy study is reported. 相似文献
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D.C.L. Cheung R.J. Barron A.R.D. Somervell T.H. Barnes 《Optics and Lasers in Engineering》2005,43(12):1292-1304
We propose and demonstrate a novel interferometric technique for 3-D displacement measurement. The method is based on the analysis of the phase difference distribution measured when two coherent curved wavefronts originating from different locations interfere. Both the in-plane and out-of-plane displacements are found simultaneously from a single phase difference distribution. We find that our system could measure with an accuracy better than 1.5 μm for in-plane displacements and 36 μm for out-of-plane displacements over 1 mm range. This accuracy was limited by the output lens performance. Theoretical analysis reveals that sub-micron accuracy may be possible with more careful calibration. 相似文献
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Digital speckle pattern interferometry (DSPI) with increased sensitivity: Use of spatial phase shifting 总被引:1,自引:0,他引:1
Basanta Bhaduri 《Optics Communications》2007,272(1):9-14
This paper presents a real-time digital speckle pattern interferometry system with twofold increase in sensitivity for the measurement of in-plane displacement and first order derivative of out-of-plane displacement (slope). Spatial phase shifting technique has been used for quantitative fringe analysis. The system employs a double aperture arrangement in front of the imaging system that introduces spatial carrier fringes within the speckle for spatial phase shifting. For in-plane displacement measurement, the scattered fields from the object are collected independently along the direction of illumination beams, and combined at the image plane. For slope measurement, a shear is introduced between the two scattered fields. Experimental results on an edge clamped circular plate subjected to in-plane rotation for in-plane displacement measurement and central loading for slope measurement are presented. 相似文献
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提出了利用相移电子散斑干涉测量物体二维变形分量的方法.单光束照明的传统电子散斑干涉技术,测量得到的是一幅物体变形的混合相位场.当物体具有对称变形时,可由这一幅相位图求得二维变形分量.方法是将该相位图镜像翻转得到第二幅相位图,通过二幅相位图的叠加、复位和分离运算,获得物体的二维变形场的分量值.利用三点加载的简支梁进行了实验,给出了实验结果,并与对称光照明实验结果进行了对比,验证了该方法的正确性. 相似文献
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Jean-José Orteu 《Optics and Lasers in Engineering》2009,47(3-4):282-291
Optical methods that give displacement or strain fields are now widely used in experimental mechanics. Some of the methods can only measure in-plane displacements/strains on planar specimens and some of them can give both in-plane and out-of-plane displacement/strain fields on any kind of specimen (planar or not). In the present paper, the stereovision technique that uses two cameras to measure 3-D displacement/strain fields on any 3-D object is presented. Additionally, a quite inclusive list of references on applications of stereovision (and 3-D DIC) to experimental mechanics is given at the end of the paper. 相似文献
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A technique to measure object shape and 3-D displacement fields in micro-scale is offered by microscopic stereo digital speckle photography. The displacement of the random features that are often present on many engineering surfaces when viewed in a microscope is measured with the system, using image correlation. In this paper the equipment, physical model and calibration routines are described. The technique can be applied for sub-mm sized objects of arbitrary shape for small deformation fields. As a verifying experiment, an in-plane rotation of a flat calibration plate is presented. The expected in-plane errors are shown to be less than 0.1 μm and the corresponding out-of-plane errors about three times larger. As a pilot experiment, micro-structural paper expansion is studied, when exposed to humidity. The scaling properties of the microscope as well as the sampling criteria and reliability of the system are discussed in detail. 相似文献