High-order wavefront sensing and control for the Roman Coronagraph Instrument (CGI): architecture and measured performance

The Nancy Grace Roman Space Telescope (Roman) is a 2.4-m space telescope scheduled for a 2026 launch. The Coronagraph Instrument (CGI) on Roman is a technology-demonstration instrument with a coronagraph and, for the first time in space, deformable mirrors and active wavefront control. We walk through the algorithmic and system-level architecture of the high-order wavefront sensing and control implementation for CGI, including the use of ground-in-the-loop operations to support computationally expensive operations, and reports on instrument performance measured during thermal vacuum testing in instrument integration and test. CGI achieved better than 5×10−8 total raw contrast with two independent coronagraph architectures covering 3–9 and 6–20 λ/D between them and a 360 deg dark hole on each. The contrast limits appear to be driven by the time available for testing and do not appear to represent a floor in the achievable performance of CGI in flight.