Pyramid wavefront sensor using a sequential operation method

The pyramid wavefront sensor is a novel slope wavefront sensor that is similar to the Foucault knife-edge test. In this paper, we describe a sequential operation method that can be realized using a micromirror array. The goal of this paper is to discuss the possibility and analyze the features of the method. Geometrical optics calculations are described first to illustrate the principle of the method. Then, more exact diffraction calculations are provided that illustrate the method being equivalent to the pyramid sensor in principle but with a weak diffraction effect. Numerical simulations are also provided to verify the feasibility of using a nonmodulation method in the closed-loop system.