End-to-end numerical modeling of AFTA coronagraphs

Abstract

The Astrophysics Focused Telescope Assets (AFTA) is one of a pair of space-qualified 2.4 meter diameter telescopes given to NASA. One plan is to use the telescope for WFIRST with a coronagraph as a secondary instrument for high contrast imaging of exoplanets and disks. Because the system is obscured by a secondary mirror and spiders, it is not the optimal unobscured configuration to which most of current proposed space coronagraphs have been designed. In the later half of 2013 a study was undertaken to evaluate coronagraphs designed specifically for the AFTA telescope. As part of this process, end-to-end numerical modeling was performed with a realistically aberrated system to determine the contrast limits of each technique. Reported here are the simulation procedures and a summary of results for four coronagraphs (hybrid Lyot, shaped pupil, vector vortex, and PIAA complex mask) evaluated for the technology downselect.