Real-time 3D part metrology using polarization rotation

This paper describes a real time, low cost part metrology method for capturing and extracting 3D part data using a single camera and no moving elements. 3D capture in machine vision is typically done using stereo photogrammetry, phase shifting using structured light, or autofocus mechanism for depth capture. These methods rely on expensive and often slow components such as multiple cameras, specialized lighting, or motion components such as motors or piezoelectric actuators. We demonstrated a method for 3D capture using only a single camera, birefringent lenses and ultra-fast electronic polarization switches. Using multiple images acquired at different polarization states and thus different focal distances, a high-resolution 3D point cloud of a test part was extracted with a good match to the ground truth data. This paper will describe the operation of the method and discuss the practical limitations.