Abstract
Digital phase-stepping shearography is a speckle interferometric technique that uses laser speckles to generate the phase map of the displacement derivatives of a stressed object, and hence can map the stresses of a deformed object directly. Conventional digital phase-stepping shearography relies on the use of video cameras of relatively lower resolution, in the order of 5 megapixels or lower, operating at a video rate. In the present work, we propose a novel method of performing high spatial resolution phase stepping shearography. This method uses a 24 megapixel still digital imaging device (DSLR camera) and a Michelson-type shearing arrangement with an edge-clamped, center-loaded plate. Different phase-stepping algorithms were used, and all successfully generated shearograms. The system enabled extremely high-resolution phase maps to be generated from relatively large deformations applied to the test plate. Quantitative comparison of the maximum achieved spatial resolution is made with the video-rate cameras used in conventional shearography. By switching from conventional (video) imaging methods to still imaging methods, significantly higher spatial resolution (by about 5 times) can be achieved in actual phase-stepping shearography, which is of great usefulness in industrial non-destructive testing (NDT).
Original language | English |
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Article number | 192 |
Journal | Journal of Imaging |
Volume | 7 |
Issue number | 10 |
DOIs | |
Publication status | Published - Oct 2021 |
Keywords
- Center-loaded plate
- Digital shearography
- High spatial resolution
- Non-destructive testing
- Phase-stepping
- Speckle interferometry
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Computer Vision and Pattern Recognition
- Computer Graphics and Computer-Aided Design
- Electrical and Electronic Engineering