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Optical Engineering

(1,N) spatial phase-shifting technique in digital speckle pattern interferometry and digital shearography for nondestructive evaluation
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Paper Abstract

Digital speckle pattern interferometry (DSPI) and digital shearography (DS) are two independent useful whole-field noncontacting optical methods for nondestructive flaw detection and precision measurements. We describe a (1,N) spatial phase-shifting technique in DSPI and DS for nondestructive evaluation (NDE) of quasidynamic behavior of objects subject to slowly varying loads. The technique employs a double-aperture arrangement in front of the imaging system to introduce spatial carrier fringes within the speckle. The prominent advantage of the proposed technique is it requires only a single frame prior to the object deformation and a number N of frames during the object deformation for NDE. Quantitative measurement of a defect and its behavior in loading conditions are studied by recording spatially phase shifted frames before and during thermal stressing of the object for continuous deformation variation with time. Experimental results on a polymethyl methacrylate (PMMA) panel using an error-compensating five-phase-step algorithm for quantitative NDE using both DSPI and DS are demonstrated.

Paper Details

Date Published: 1 May 2007
PDF: 7 pages
Opt. Eng. 46(5) 051009 doi: 10.1117/1.2740749
Published in: Optical Engineering Volume 46, Issue 5
Show Author Affiliations
Basanta Bhaduri, Indian Institute of Technology Madras (India)
Nandigana Krishna Mohan, Indian Institute of Technology Madras (India)
Mahendra Prasad Kothiyal, Indian Institute of Technology Madras (India)

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