13 October 1999 3D shearography for surface strain analysis
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The development of a time-division-multiplexed 3D digital shearography instrument is described. The system provides simultaneous measurement of the in-plane and out-of-plane deformation gradients, allowing full surface strain analysis. The object under investigation is sequentially illuminated from three directions by three fiber coupled high power laser diode sources, and imaged onto a CCD camera through a single shearing interferometer. The pulsing of the sources is synchronized with the camera frame rate. Phase stepping is achieved using laser diode wavelength tuning combined with a path length imbalance in the shearing interferometer. The source pulsing schedule and image acquisition are controlled from a PC. An analysis of the optimum illumination geometry is presented. The performance of the system is evaluated on laboratory test samples.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stephen W. James, Ralph P. Tatam, "3D shearography for surface strain analysis", Proc. SPIE 3783, Optical Diagnostics for Fluids/Heat/Combustion and Photomechanics for Solids, (13 October 1999); doi: 10.1117/12.365743; https://doi.org/10.1117/12.365743

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