Autofocusing method for high-resolution three-dimensional profilometry

State-of-the-art high-accuracy three-dimensional (3D) profilometry systems typically use a lens with a fixed focal length, making it difficult for them to measure scenes with large depth variations, especially dynamically changing ones. To address this need, this Letter proposes a novel, to the best of our knowledge, autofocusing method for high-resolution 3D profilometry with a digital fringe projection technique by (1) developing a novel continuous geometric parameter model for systems using electrically tunable lenses and (2) employing a focal plane detection algorithm. The validity of the proposed method is confirmed by experiments.