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- Title
Measurement of the defect size by shearography or other interferometric techniques.
- Authors
Michel, Fabrice; Renotte, Yvon L.; Habraken, Serge
- Abstract
Shearography is an interferometric technique suitable for detecting defects because they yield singular fringes and high phase values in wrapped and unwrapped phasemaps, respectively. We propose a methodology that leads to the defect size from unwrapped phasemap by extracting the size of the high phase values area. The area size is evaluated, thanks to a wavelet transform algorithm that enables the location of its borders. The performances of the methodology and of the algorithm have been tested by applying them on a defect where the size is known. An error less than 1.5% root mean square was reached. Our approach is independent of the shearing amount and of the phase profile, and it can be extended for other interferometric techniques.
- Subjects
SHEAROGRAPHY; INTERFEROMETRY; HOLOGRAPHY; NONDESTRUCTIVE testing; WAVELET transforms; SHEARING interferometers; PHASE-shift masks
- Publication
Optical Engineering, 2012, Vol 51, Issue 3, p033602-1
- ISSN
0091-3286
- Publication type
Article
- DOI
10.1117/1.OE.51.3.033602