A technique for separating the in-plane and out-of-plane motions of a tested object in hologram interferometry is described. In this technique, the object is illuminated with two symmetrically oriented beams, and an image plane hologram is recorded in photoconductor–thermoplastic devices which can be developed in situ and in virtually real time. Then the hologram is read out with the object waves only, thereby reconstructing the reference beam. If the object is moved or deformed during readout, fringes denoting equal in-plane motion appear as long as the motion is less than the speckle size. The exact arrangement is presented along with experimental results, which are compared with conventional holographic interferometry results.
© 1982 Optical Society of America
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