Holographic interferometry produced by coherent laser light can be used to de¬tect three-dimensional displacements as small as 12 μin. on a complex curved surface of a structure deformed by either stresses or temperature gradients and displacements caused by solid-body motion. With this technique, the measuring apparatus is independ¬ent of the surface being measured which is an advantage over strain-gauge or photoelasticity techniques. A computer code was developed to give quantitative and qualitative interpretation in the form of displacement contour lines.
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