Point Diffraction Interferometer: A simple diagnostic tool for metalenses characterization

This work describes the development and testing of a diagnostic technique, based on a robust setup named Point Diffraction Interferometer, to characterize the wavefronts generated by metalenses. The presented optical setup is simple, cheap and insensitive to mechanical disturbances, nevertheless precisely capable to reconstruct the radiation wavefront produced by a metalens. The obtained interference patterns exhibit suitable contrast ratio of the fringes and high spatial resolution, thus allowing the detection of even highly distorted wavefronts, and providing a measurable information about the metalens properties.