Modeling and Performance Analysis of iEFC for the Roman/CGI SPC Mode

High-order wavefront sensing and control (HOWFSC) is key to creating a dark hole region within the coronagraphic image plane where high contrasts are achieved. The Roman Coronagraph is expected to perform its HOWFSC with a ground-in-the-loop scheme due to the computational complexity of the electric field conjugation (EFC) algorithm. The baseline HOWFSC scheme involves running EFC while observing a bright star such as ζ Puppis to create the initial dark hole followed by a slew to the science target. The implicit EFC (iEFC) algorithm is a new variant of EFC that removes the optical model from the controller, making the final contrast independent of model accuracy. First, an overview of EFC and iEFC is provided along with a demonstration of iEFC applied to a vortex coronagraph with a single DM. Similar to EFC, the iEFC method is extended to two deformable mirror systems to create annular dark holes and applied to the wide-field-of-view shaped pupil coronagraph (SPC-WFOV) mode using end-to-end physical optics models. These simulations demonstrate that iEFC can be a feasible method for the SPC-WFOV mode as 1E-8 contrasts are achieved. Given iEFC is model-independent, it can also help mitigate any risks associated with calibrating a model while Roman is in orbit.

Speaker: Kian Milani (University of Arizona)

The Roman Lecture Series is a monthly virtual lecture series focused on the scientific capabilities and technology of the Nancy Grace Roman Space Telescope, organized by Roman Mission partners.