Continual deformation analysis with scanning phase method and time sequence phase method in temporal speckle pattern interferometry

If a laser beam illuminates a continual deformation object surface, it will lead to a temporal speckle pattern on the observation plane. Recording thi s time-dependent speckle pattern the deformation of the surface of an objec t can be obtained. Two methods, scanning phase method (SPM) and time sequen ce phase method (TSPM), have been introduced for measuring the displacement caused by the deformation in temporal speckle pattern interferometry (TSPI ). Their principle is that by capturing a series of speckle interference pa tterns related to the object deformations, the fluctuations in the intensit y of the interference patterns can be obtained. Through scanning these fluc tuations and estimating both the average intensity and modulation of the te mporal speckle interference patterns, the phase maps for whole-field displa cements are calculated. In this way one is capable of quantitatively measur ing continual displacements simply using a conventional electronic speckle pattern interferometry (ESPI) system without phase shifting or a carrier. T he elaboration on the new methods is given in this paper and experiments ar e performed to demonstrate their performance with a conventional ESPI syste m. (C) 2001 Elsevier Science Ltd. All rights reserved.