6 April 2012 Measurement of the defect size by shearography or other interferometric techniques
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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.
© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)
Fabrice R. Michel, Fabrice R. Michel, Yvon L. Renotte, Yvon L. Renotte, Serge Habraken, Serge Habraken, } "Measurement of the defect size by shearography or other interferometric techniques," Optical Engineering 51(3), 033602 (6 April 2012). https://doi.org/10.1117/1.OE.51.3.033602 . Submission:
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