The high-contrast performance of an optical vortex coronagraph

Abstract

The goal of the Terrestrial Planet Finder Mission is to detect and characterize Earth-like planets. Detection of these faint objects, which appear very close to their parent stars, requires a coronagraph capable of achieving better than 10^-10 starlight suppression within a few Airy rings of the stellar image. The coronagraph is also required to maintain this high stellar extinction over a 100nm spectral bandwidth. To ease requirements on the telescope, a high planet light throughput and low sensitivity to wave front aberrations are also desirable features. An optical vortex coronagraph is a promising candidate architecture, which makes use of a spiral phase plate placed in an intermediate image plane to null out the stellar signal. This architecture has the advantage of high stellar extinction, high planet light throughput, and low sensitivity to wave front aberrations. Here we report the high contrast performance of an optical vortex coronagraph limited by the manufacturability of the spiral phase plate.