Phase-shifting interferometry with uncalibrated phase shifts

A computationally efficient algorithm for phase-shifting interferometry wit h imprecise phase shifts is developed. It permits the use of an uncalibrate d phase shifter and is also insensitive to spatial intensity variations. Th e measurement has both spatial and temporal aspects. Comparisons are made b etween pixels within the same interferogram, and these comparisons are exte nded across a set of interferograms by a maximum-minimum procedure. A test experiment is performed and confirms the theoretical results. An additional advantage of the algorithm is that an error measure can be developed. This error measure is used to implement an error correction scheme. (C) 2000 Op tical Society of America.