Optical vortex beams for optical displacement measurements in a surveying field

Significant propagation properties of optical vortex beams with an on-axis single singular point for displacement measurement applications are proposed: the preservation of the singularity structure, including the conically shaped structure of the amplitude distribution, especially, its sharp structure, and the circulating structure of the phase distribution around the singular point through free-space propagation. Through theoretical analyses, simulations and basic experiments, it is verified that optical vortex beams are very effective for performing both rotational and translational displacement measurements simultaneously in the surveying field.