A Coronagraph Based on Stepped" Transmission Filters
We propose a coronagraph for direct imaging of Earth‐like planets orbiting nearby bright stars. The coronagraph is based on an apodization pupil composed of two stepped‐transmission filters. We show that the coronagraph can achieve 10−10 high‐contrast imaging at an angular distance larger than (2-3)λ/D theoretically. The employment of the stepped‐transmission filters significantly simplifies the manufacturing of the transmission pupil, making it possible to be used for high‐contrast imaging in practice.