One‐sided Achromatic Phase Apodization for Imaging of Extrasolar Planets

Abstract

We propose a new approach to direct imaging of extrasolar planets: one-sided phase apodization. It is based on a discovery that an antisymmetric spatial phase modulation pattern imposed over a pupil or a relay plane causes diffracted starlight suppression sufficient for imaging of extrasolar planets. Calculations with specific square-pupil (side D) phase functions, such as demonstrate annulling in at least one quadrant of the diffraction plane to the contrast level of better than 10-12, with an inner working angle down to 3.5λ/D (with a = 3 and = 10-3). Furthermore, our computer experiments show that phase apodization remains effective throughout a broad spectrum (60% of the central wavelength) covering the entire visible-light range. Phase-only modulation has the additional appeal of potential implementation via active segmented or deformable mirrors, thereby combining compensation of random phase aberrations and diffraction halo removal in a single optical element.