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

April 2025 • 2025JATIS..11b1408C

Authors • Cady, Eric • Bowman, Nicholas • Greenbaum, Alexandra Z. • Ingalls, James G. • Kern, Brian • Krist, John • Marx, David • Poberezhskiy, Ilya • Eldorado Riggs, A. J. • Ruane, Garreth • Seo, Byoung-Joon • Shi, Fang • Zhou, Hanying

Abstract • 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.

Links

• PREPRINT http://arxiv.org/abs/2507.23738
• ELECTR https://doi.org/10.1117%2F1.JATIS.11.2.021408