Single-shot spatial frequency multiplex fringe pattern for phase unwrapping using deep learning

Fringe projection profilometry (FPP) has been widely applied in three-dimensional (3D) measurement owing to its high measurement accuracy and simple structure. In FPP, how to effectively recover the absolute phase, especially through a single image, has always been a huge challenge and eternal pursuit. The frequency-multiplex methods can maximize the efficiency of phase unwrapping by mixing the multi-frequency information used to eliminate phase ambiguity in the spectrum. However, spectrum aliasing and the resulting phase unwrapping errors are still pressing difficulties. Inspired by the successful application of deep learning in FPP, we propose a single-shot frequency multiplex fringe pattern for phase unwrapping approach using deep learning. Through extensive data learning, the properly trained neural networks can directly learn to obtain spectrum-aliasing-free phase information and robust phase unwrapping from single-frame compound input. Experimental results demonstrate that compared with convenient frequency-multiplex methods, our deep-learning-based approach can achieve more accurate and stable absolute phase retrieval.