High speed implementation of a three-dimensional shape profiler with submillimeter precision using a digital light processing device and a new efficient algorithm for absolute phase retrieval

The processing of structured light images in real time is a challenging task for the development of three-dimensional (3-D) shape measurement methods. This paper presents a high speed and low-cost optical profiler implemented using a projection method based on the use of a digital light-processing device to illuminate the object to be measured. The image processing of the reflected structured light pattern allows potential realtime capabilities. The proposed method of absolute phase retrieval for unwrapping the relative phase uses a single additional staircase intensity pattern to determine and correct 2 pi discontinuities in the phase. Good results are obtained when the method is compared to another which uses three additional fringe patterns to determine the stair phase and then the absolute phase. Since the proposed technique uses only one extra pattern instead of three, it is less costly in terms of computation complexity and is thus faster. The hardware of the developed fringe projection system for a 3-D macroscopic reconstruction is presented and the performance of the method is evaluated. Simulated and experimental results are presented and compared to the other absolute phase-retrieval method. The proposed method is suitable for measuring 3-D object surfaces for a possible implementation in real time. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)