Uneven illumination is a common problem in practical optical systems designed for machine vision applications, and it leads to significant errors when phase-shifting algorithms (PSA) are used to reconstruct the surface of a moving object. We propose an illumination-reflectivityfocus model to characterize this uneven illumination effect on phase-measuring profilometry. With this model, we separate the illumination factor effectively and consider the phase reconstruction from an optimization

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... ective. Furthermore, we formulate an illumination-invariant phaseshifting algorithm (II-PSA) to reconstruct the surface of a moving object under an uneven illumination environment. Experimental results show that it can improve the reconstruction quality both visually and numerically. Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 09/10/2013 Terms of Use: http://spiedl.org/terms