Unwrapping of electronic speckle pattern interferometry phase maps: evaluation of an iterative weighted algorithm

Abstract

Since current fringe analysis techniques used in electronic speckle pattern interferometry (ESPI) yield a phase map modulo 2p, phase unwrapping is the final step of any data evaluation process. In this paper the performance of a recently published unwrapping algorithm is investigated. The algorithm is based on a least-squares minimization technique solvable in an iterative manner by the discrete cosine trans- form. Phase inconsistencies are handled by excluding invalid pixels from the unwrapping process through the assignment of zero-valued weights. The study is carried out using computer simulated ESPI phase maps, an approach which allows us to generate noise-free phase fields that are used to calculate phase deviations as a function of the iteration number. © 1998 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(98)01902-3) Subject terms: phase unwrapping; speckle; interferometry; cosine transform.