1 May 2007 Improved speckle method for measuring in-plane displacement and strain fields
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Optical Engineering, 46(5), 051005 (2007). doi:10.1117/1.2739610
Abstract
An improved method to compute the displacement field and strain field from the speckle recorded from a CCD camera is proposed. Previous studies have shown that the displacement field can be determined from two neighboring speckle images using the fast Fourier transform. Moreover, the accuracy of determining the displacement field in this manner relies on the ability to determine the peak position of the Fourier spectrum precisely. We present an improved method that can measure the displacements to an accuracy of 2 μm, provided that the distance between two pixels corresponds to 0.1 mm. The algorithm developed to obtain the displacement field uses the usual assumption that the displacements within each subelement of the image are constant and evaluated at the center of the subelement. However, instead of moving the entire subelement in each loop of the algorithm, a fraction of the subelement size is adopted to generate a family of overlapping subelements, resulting in an enhanced resolution of the resulting displacement field.
Hseng Ji Huang, Anthony M. Waas, "Improved speckle method for measuring in-plane displacement and strain fields," Optical Engineering 46(5), 051005 (1 May 2007). http://dx.doi.org/10.1117/1.2739610
JOURNAL ARTICLE
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KEYWORDS
Speckle

Fourier transforms

Optical engineering

Algorithm development

Speckle pattern

CCD cameras

Image analysis

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