25 March 1999 New shearing setup for simultaneous measurement of two shear directions
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Shearography is a full field interferometric technique for the measurement of small deformation gradients. The main fields of application are non-destructive testing in quality control and material inspection. In both cases the direction of the deformation gradient plays a major role. We present a new image shearing speckle pattern interferometer set-up for simultaneous measurement of two independent deformation gradients equivalent to two shear directions. Herein, we use the polarization effect to separate the two directions. Based on a Michelson interferometer, we placed in one arm an additional polarization beamsplitter (PBS) and an additional mirror. The two orthogonal polarized images can be separated by a further PBS and simultaneously captured by a second camera. Substituting the second PBS with a rotatable polarizator and using only one camera, both sheared images can be recorded in rapid succession. We make use of a liquid crystal cell as a fast rotating polarizator and demonstrate the utility of this new concept with measurements in an industrial environment on a tensile testing machine.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thorsten Siebert, Bernhard Schmitz, "New shearing setup for simultaneous measurement of two shear directions", Proc. SPIE 3637, Practical Holography XIII, (25 March 1999); doi: 10.1117/12.343778; https://doi.org/10.1117/12.343778

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