High-quality 3D shape measurement using saturated fringe patterns

This paper proposes a method to potentially conquer one of the challenges in the optical metrology community: optically measuring three-dimensional (3D) objects with high surface contrast. We discover that for digitally equally phase-shifted fringe patterns, if the fringe period P is art even number, the N = P/2 x k, (k=1, 2, 3, ...) step algorithm can accurately recover phase even if the fringe patterns are saturated; and if P is an odd number, N = P x k step algorithm can also accurately recover phase even if the fringe patterns are saturated. This finding leads to a novel method to optically measure shiny surfaces, where the saturation due to surface shininess could be substantially alleviated. Both simulations and experiments successfully verified the proposed method. (C) 2016 Elsevier Ltd. All rights reserved.