PC-based determination of 3-D deformation using holographic interferometry

It is shown that a three-dimensional analysis of the deformation of a planar surface can be performed utilizing holographic interferometry and by simple and relatively inexpensive means. In order to obtain the in-plane deformations in addition to the out-of-plane deformation, a single interferogram resulting from the double exposure of two states with different mechanical loads has been viewed from at least three noncoplanar directions. The image distortion due to the perspective projection has been taken into account and a simple algorithm found to decompose the three deformations along the orthogonal coordinate axes. For the electronic recording, the fringe interpolation, and the demodulation of the two π ambiguity, commercially available software has been used. This system has been applied to the investigation of a model drill tip under different compressive loads.