Orbital angular momentum-based Fizeau interferometer measurement system

In this study, a robust orbital angular momentum (OAM) beams-based Fizeau interferometer is proposed and experimentally demonstrated. It takes full advantages of the Fizeau interferometer and OAM beams, where two conjugated OAM beams propagate in a common optical path. Compared with the conventional dual-path interferometers, Fizeau interferometer has a simpler structure and higher stability, for its common optical path structure is less sensitive to the effects of the external perturbations. As a result, petal-like interference patterns can be stably observed on a CCD. By measuring the rotation angle of the petal-like pattern, tiny displacements ranging from 50 to 800 nm were stably and precisely measured with resolution of 40 pm in simulation and 750 pm in experiment. The proposed system may develop a more compact and stable scheme for the precision measurement in the future.