Flight mask designs of the Roman Space Telescope coronagraph instrument

The Nancy Grace Roman Space Telescope, planned to launch in the mid-2020s, will be the first space-based observatory to demonstrate active wavefront correction at high contrast with its Coronagraph Instrument. As a technology demonstrator, the instrument’s main purpose is to mature the various technologies needed by future flagship mission concepts that aim to image and characterize Earth-like exoplanets. These technologies include two high-actuator-count deformable mirrors (DMs), photon-counting detectors, two complementary wavefront sensing and control loops, and two different coronagraph types. Here we describe the complete set of flight mask designs for the Roman Coronagraph. Multiple mask configurations are required to overcome the challenging pupil obscurations and enable the desired types of imaging, spectroscopy, and polarimetry. In designing each mask configuration, we considered many performance metrics, including spectral bandwidth, field of view, contrast, core throughput, encircled energy, deformable mirror surface height, and low-order aberration sensitivity