Model-based inversion of speckle interferometer fringe patterns

摘要

Micrometer-scale rigid-body translations are determined from electronic speckle interferometric fringe patterns. An iterative minimum error procedure employs the relative hinge order of picked positions of fringe maxima and minima within a single interferogram to calculate the displacement field directly. The method does not calculate the displacement at a single point but relies on the assumption that the character, but not the magnitudes or directions, of the displacements over the viewing area of the interferogram is known. That is, a model of the displacements exists. On perfect,noise-free forward modeled fringe patterns calculated for an 8.0-mu m displacement, the phase error is less than 2 x 10(-6) fringe orders (1.3 x 10(-5) rad) and probably results only from numerical noise in the inversion. On real fringe patterns obtained in electronic speckle interferometric experiments, mean phase errors are generally less than 5 x 10(-5) fringe orders (3.2 x 10(-4) rad), suggesting that;the technique is robust despite errors resulting from speckle noise, lack of accuracy in positioning of experimental components, and image-distortion corrections. (C) 1998 Optical Society of America. [References: 12]