Topic
Speckle imaging
About: Speckle imaging is a research topic. Over the lifetime, 3730 publications have been published within this topic receiving 62354 citations.
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TL;DR: In this paper, a noncontact, non-destructive remote fatigue damage monitoring technique is described, which employs a laser beam that illuminates the surface of a cyclically loaded specimen, and an image processing system that extracts fatigue damage related information in the speckle pattern scattered from the surface.
16 citations
TL;DR: The experimental results indicate that the two presented robust estimators can suppress the effects of the abnormality in the speckle images and, meanwhile, keep higher precision in vibration measurement in contrast with the traditional SSD method.
Abstract: Discrepancies of speckle images under dynamic measurement due to the different viewing angles will deteriorate the correspondence in 3D digital image correlation (3D-DIC) for vibration measurement Facing this kind of bottleneck, this paper presents two types of robust 3D-DIC methods for vibration measurement, SSD-robust and SWD-robust, which use a sum of square difference (SSD) estimator plus a Geman–McClure regulating term and a Welch estimator plus a Geman–McClure regulating term, respectively Because the regulating term with an adaptive rejecting bound can lessen the influence of the abnormal pixel data in the dynamical measuring process, the robustness of the algorithm is enhanced The robustness and precision evaluation experiments using a dual-frequency laser interferometer are implemented The experimental results indicate that the two presented robust estimators can suppress the effects of the abnormality in the speckle images and, meanwhile, keep higher precision in vibration measurement in contrast with the traditional SSD method; thus, the SWD-robust and SSD-robust methods are suitable for weak image noise and strong image noise, respectively
16 citations
TL;DR: Amplitude and phase of both in-plane and out-of-plane vibration components are measured in real time using heterodyne speckle interferometry to permit complete determination of the mechanical movement of a vibrating surface.
Abstract: Amplitude and phase of both in-plane and out-of-plane vibration components are measured in real time using heterodyne speckle interferometry Microvibrations with amplitudes down to 1 nm and frequencies up to 5 MHz were analyzed at a spatial resolution of 35 μm Amplitude and phase measurements were performed with an accuracy of better than 6% and 4°, respectively This permits complete determination of the mechanical movement of a vibrating surface
16 citations
TL;DR: In this article, a digital speckle pattern shearing interferometer is presented, which utilizes a single birefringent wedge to shear two orthogonally polarized images of an object measured, and the bias phase difference between two polarized images is shifted by translating the wedge.
16 citations
TL;DR: A new, to the authors' knowledge, method using wavelets and probability theory for the evaluation of speckle interference patterns for quantitative out-of-plane deformation measurements of rough surfaces of nontransparent solids is introduced.
Abstract: We introduce a new, to our knowledge, method using wavelets and probability theory for the evaluation of speckle interference patterns for quantitative out-of-plane deformation measurements of rough surfaces of nontransparent solids. The experiment uses a conventional Twyman-Green interferometer setup. The speckle interference patterns are obtained by the common method of subtraction of images taken before and after a surface deformation. The data are processed by a wavelet transformation, which analyzes the image structures on different length scales. Thus it is possible to separate the interference fringes from the noise. From the locations of the interference fringes, the deformation of the surface can be reconstructed by means of probability theory.
16 citations