Simple real-time 3-D displacement measurement by fringe analysis using a photorefractive interferometer

A simple 3-D displacement measurement method using a photorefractive interf erometer is proposed and experimentally demonstrated. A photorefractive cry stal attached to the sample under test is used to record an original spheri cal wave that provides a shifted reconstructed wave after displacement. The shifted wave interferes with direct wave to form an interferogram. By anal yzing the fringe pattern the in-place and out-of-place displacements can be determined at the same time. This method works in real-time and is easy to operate with adequate accuracy comparable with or even better than that of other techniques. (C) 2000 Elsevier Science Ltd. All rights reserved.