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Proceedings Paper

Electronic shearography for nondestructive evaluation: the influence of the field of view and the shearing angle
Author(s): John B. Deaton Jr.; Robert S. Rogowski
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Paper Abstract

Electronic shearography, a variation of electronic speckle pattern interferometry (ESPI), is a promising new technology for non-contacting, full-field optical nondestructive inspection. In this technique, the shearographic fringe pattern is generated electronically and updated at the video frame rate of the camera. Therefore, the results of an inspection procedure may be viewed in real time, offering a significant advantage over film-based interferometric techniques such as holographic interferometry. This work examines several opportunities to adjust system parameters to optimize the detection resolution of electronic shearography when used for nondestructive flaw detection. For any application, the required detection resolution must be balanced against the practical need to maximize the field of view of the inspection window, and thus the speed of the inspection. The magnitude of the image shear also plays an important role, because it controls the measurement sensitivity of shearography. The interaction of these principles is demonstrated for the detection of disbonds behind thin aluminum face sheets using vacuum stressing. The experimental results were obtained using a compact, portable electronic shearography system which incorporated a skewed-Michelson interferometer configuration. This arrangement allowed easy adjustment of both the direction and magnitude of the image shear at any working distance.

Paper Details

Date Published: 22 October 1993
PDF: 12 pages
Proc. SPIE 2066, Industrial Optical Sensing and Metrology: Applications and Integration, (22 October 1993); doi: 10.1117/12.162099
Show Author Affiliations
John B. Deaton Jr., Analytical Services & Materials (United States)
Robert S. Rogowski, NASA Langley Research Ctr. (United States)

Published in SPIE Proceedings Vol. 2066:
Industrial Optical Sensing and Metrology: Applications and Integration
Kevin G. Harding; H. Philip Stahl, Editor(s)

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