共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
采用两套旋转孔径散照相系统对动态三维位移场进行了研制。一次实验可把缓慢连续变形的动态三维移场的整个变化过程记录于两张散斑图上。对散斑图进行全场滤波可摄取所有各时刻的三个位移分量的信息。 相似文献
3.
4.
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
5.
测量物体位移的数字白光散斑照相术 总被引:2,自引:1,他引:1
给出了一测量物体刚体位移的数字白光散斑照相术。数字傅里叶变换从双曝光字白光散斑图用来产生杨氏条纹。该杨氏条纹能够用数字傅里叶变换结合条纹重构进行自动分析。此外,给出一种条纹质量增强的方法。 相似文献
6.
电子散斑干涉位移场分离技术及其在三维测量中的应用 总被引:6,自引:3,他引:3
提供了一种可将离面位移与面内位移分离的三维位移场测量方法.在双光束电子散斑干涉中增加参考光,使这一路参考光为两光束所共用.两束光各自独立地对变形物体进行测量,结合相移技术,可分别得到包含离面和面内位移信息的二幅位相图.只需简单的位相运算就能够将面内位移场与离面位移场分离.在竖直方向上,采用两光束对称照明被测物,直接测量面内位移竖直方向分量.本文将该技术应用到柴油机油泵测量上,得到了油泵的三维位移场.该技术为三维位移场的测量提供了一种新的有效途径,也为柴油机零部件的强度和刚度分析评价提供了新的方法. 相似文献
7.
8.
9.
采用两套旋转孔径散斑照相系统对动态三维位移场进行了研测。一次实验可把缓慢连续变形体的动态三维位移场的整个变化过程记录于两张散斑图上.对散斑图进行全场滤波可摄取所有各时刻的三个位移分量的信息。 相似文献
10.
11.
A speckle photographic technique is used for visualizing the planar distribution of the refractive deflection angles of light transmitted through the compressible turbulent flow. Both double and single (prolonged) exposure speckle photography are applied for statistical analysis of such flows. Using single (prolonged) exposure speckle photography (SPESP), instantaneous quantitative measurement of 2-D distribution of turbulence intensity in a flame is performed. Anisotropy of turbulence is visualized by a diffraction halo form and quantitatively evaluated by measuring the diffraction halo diameters. Using double exposure speckle photography (DESP), quantitative visualization of the planar distribution of the refractive deflection angles of the light transmitted through the compressible turbulent flow is done. Turbulent structures are visible in the patterns of the deflection angles isolines. The 2-D correlation functions of these deflection angles are constructed and analyzed. The 3-D density correlation functions are evaluated using the Erbeck–Merzkirch integral transformation. 相似文献
12.
The combination of image plane holography and speckle photography for measurement of 3-D displacements has been reported earlier. It has been observed that when we interrogate such a hologram by an unexpanded laser beam, in addition to the formation of Young's fringes in the direct diffracted beam, very bright side lobes are also generated. If the specimen has undergone any in-plane displacement, high contrast fringes appear in the side lobes. We have demonstrated that these fringes can be used to obtain a precise quantitative in-plane displacement of the object. 相似文献
13.
D. A. Gregory 《Optics & Laser Technology》1976,8(5):201-213
This paper describes the basic physical principles of defocused speckle photography, and how tilt (differential) topology variations on a scatter surface may be separated from linear displacements. Several rather special features about the scattering process have been revealed, such as the laser source distance from the scatter surface must be considered as well as the light incidence angle. Also, the surface must be treated as mirror facet discontinuities for linear displacements using ray and intensity analogies, and surface topology must be treated in terms of phase and pathlength changes, and a continuous smooth surface. The complementary relationship between focused speckle photography and defocused (topological) speckle photography is shown using specially developed separation techniques. This demanded a detailed look at the ‘speckle process’. The basic physical principles, together with an appropriate analysis technique for the developed speckle photographs, have enabled very small faults and indentations on engineering structures to be detected and measured. 相似文献
14.
Applications of speckle interferometry for measuring displacements of mirrors of multi‐mirror centimeter radiotelescopes are
considered and analyzed in modeling experiments. The general principles of speckle photography, speckle interferometry, and
the use of two-exposure speckle patterns for the analysis of displacements of rough surfaces (units of the radiotelescope
mirrors) are worked out. Experiments are carried out for three possible displacements of the object surface: parallel shifts
along the surface itself, rotations, and shifts in the perpendicular direction. The shape and structure of the displaced units
do not change. The experiments prove that speckle interferometry is a rather effective and practical tool for measuring shifts
and rotations of composite radiotelescope mirrors. 相似文献
15.
Zhengyuan Cao Jianxin Gao Shaode Gu Guohong Zhang 《Optics and Lasers in Engineering》2005,43(10):1127-1136
We report a method measuring 3-D displacement of cambered mirror for cryogenic optical system using white light speckle photography with double light sources and double cameras. Data acquiring and processing based on a digital image processing system is described. The 3-D displacement and displacement vector distributions in two low-temperature ranges are measured. 相似文献
16.
M. Sjdahl 《Optics and Lasers in Engineering》1998,29(2-3)
Major advances in electronic speckle photography are reviewed. Topics include the correlation properties of laser speckles, the principles and expected accuracy of electronic speckle photography, the effect of the digital recording and evaluation, and some recent applications. These applications involve two techniques for the measurement of 3D deformation fields, measurement of the in-plane strain field components using defocused laser speckle, and measurement of object shape. 相似文献
17.
A procedure for extending the limits of measurable displacements by the method of double exposure speckle photography displacements is proposed. It is based on an introduction of a known movement of the recording camera in the direction perpendicular to the line of sight between the two exposures. 相似文献
18.
19.
Speckle photography experiments have been used for studying optical systems and more recently we have used image speckle photography to measure displacements and deformations of a partial diffuser. The same method is now used for studying chromatic aberrations of a lens system. Experimental results are given for three optical lenses. 相似文献
20.
Transient out-of-plane displacements generated in a steel cantilever beam by an impact load are measured using a double-pulsed electronic speckle pattern interferometry system. The state of deformation of the object is freezed using a ruby laser and the pulse emission is synchronised with the impact load. Correlation fringes for different times after the start of the impact are obtained using a digital image system. For each time, transient displacements are evaluated by digital analysis of the fringes. In order to test the experimental results, the time response of the beam subjected to the impact load is evaluated using a 3-D finite element analysis. A close agreement is found between the experimental and numerical results, which prove the reliability of the optical technique to measure high-speed transient deformations. 相似文献