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Artificial grid making geometric phase analysis method based on local high-resolution Fourier transformation

A Fourier transform, high-resolution technology, applied in the field of experimental mechanics and optical testing, can solve the problems of calculation error of the main value of spatial frequency, difficulty in obtaining fast Fourier transform accurately, etc., to achieve accurate value and short calculation time , the effect of improving the calculation accuracy

Inactive Publication Date: 2013-07-24
TSINGHUA UNIV
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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that fast Fourier transform is difficult to accurately obtain the main value of spatial frequency and cause calculation error

Method used

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  • Artificial grid making geometric phase analysis method based on local high-resolution Fourier transformation
  • Artificial grid making geometric phase analysis method based on local high-resolution Fourier transformation
  • Artificial grid making geometric phase analysis method based on local high-resolution Fourier transformation

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Embodiment 1

[0064] An orthogonal grating with a frequency of 20 lines / mm was fabricated on the surface of the aluminum specimen by photolithography. Put the specimen on the loading device, and use a digital camera to collect an orthogonal grating image before deformation as a reference image. A force load is applied to the aluminum specimen, and a digital camera is used to collect the deformed orthogonal grating image as the deformed image. For the convenience of description, only the x direction is taken as an example for illustration.

[0065] Fast Fourier transform is performed on the reference image to obtain the reference spatial frequency spectrum. In the reference spatial frequency spectrum, the interval of the largest amplitude value is selected as the interval of the main value of the spatial frequency. The formula (1) is used to perform local high-resolution Fourier transform in the interval of the main value of the spatial frequency to obtain the local high-resolution referen...

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Abstract

The invention provides an artificial grid making geometric phase analysis method based on local high-resolution Fourier transformation. The method comprises the following steps of firstly collecting an undeformed raster image and a deformed raster image; respectively performing fast Fourier transformation on a reference image and a deforming image; acquiring a reference spatial frequency spectrum and a deformation spatial frequency spectrum, and selecting the interval where a spatial frequency main value is positioned to perform the local high-resolution Fourier transformation to obtain a local high-resolution spatial frequency spectrum; determining the spatial frequency main value in the local high-resolution spatial frequency spectrum and taking the spatial frequency main value as a center to select a spatial frequency value; filtering on the spatial frequency spectrum formed by the selected spatial frequency value so as to obtain a filtering reference spectrum and a filtering deformation spectrum, and then performing Fourier inversion and solving a reference phase and a deformation phase; and solving a phase difference by using the reference phase and the deformation phase, and calculating displacement and strain. The displacement and strain result calculated by the method is high in precision and short in calculation time.

Description

technical field [0001] The invention relates to a geometric phase analysis method, in particular to an artificial grating geometric phase analysis method, which belongs to the field of experimental mechanics and optical testing. Background technique [0002] Geometric phase analysis by proposed by et al., for computing the local deformation of the lattice. Year 2003 et al. used the geometric phase method to measure the dislocation of silicon atoms, and the measurement accuracy reached 0.003nm. Liu Zhanwei and others have done a lot of work in this area, applied the geometric phase method to the deformation measurement of objects with irregular grid structures, and proposed the artificial grid geometric phase analysis method. For details, see the literature "Liu Z W, Huang X F, Xie H M , et al.The artificial periodic lattice phase analysis method applied to deformation evaluation of TiNi shape memory alloy in micro scale.Measurement Science and Technology,2011,22(12):125...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T3/00G06F17/14
Inventor 谢惠民戴相录王怀喜吴立夫
Owner TSINGHUA UNIV
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