From concept to reality: computing visual vortex beam interferometer for displacement measurement

Abstract

In addition to the concept of picometer resolution, we discuss macro displacement measurement with a vortex beam interferometer. Three factors limiting large displacement measurement are resolved. Small topological charge numbers promise both high sensitivity and large displacement measurements. With a computing visual method, a virtual moiré pointer image immune to beam misalignment is proposed to calculate displacements. Interestingly, the absolute benchmark is found for cycle counting in the moiré pointer image of fractional topological charge. The vortex beam interferometer would not stop at the tiny displacement measurement in simulations. We report experimental measurements of nanoscale to hundred millimeter displacement in a vortex beam displacement measurement interferometer (DMI) for the first time, to the best of our knowledge.