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 fringe 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 8.0-1xm displacement, the phase error is less than 2×10↑(-6) fringe orders (1.3×10↑(-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 5×10↑(-5) fringe orders (3.2×10↑(-4) red), suggesting that the technique is robust despite errors resulting from speckle noise, lack of accuracy in positioning of experimental components, and image-distortion corrections.#1998 Optical Society of America OCIS codes: 120.3180, 100.0100, 090.0090, 120.2650.