Unwrapping of ESPI phase maps using a preconditioned conjugate gradient algorithm

摘要

The performance of a recently published phase unwrapping algorithm based on a least-squares minimization technique solvable by the discrete cosine transform is investigated. When phase inconsistencies are present, they are handled by excluding invalid pixels from the unwrapping process through the assignment of zero-valued weights. Then, the weighted unwrapping problem is solved iteratively using a preconditioned conjugate gradient method. The computer generation of electronic speckle pattern interferometry fringes allow to obtain phase fields without inconsistencies, which are used to calculate phase deviations as a function of the iteration number for different situations.