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arXiv · 2507.23738

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

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

The Nancy Grace Roman Space Telescope (``Roman'') is a 2.4m 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. This paper walks through the algorithmic and system-level architecture of the HOWFSC implementation for CGI, including the use of ground-in-the-loop (GITL) 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 $5\times10^{-8}$ total raw contrast with two independent coronagraph architectures covering 3-9 and 6-20 $\lambda/D$ between them and a $360^{\circ}$ dark hole on each. The contrast limits appear to be driven by time available for testing, and do not appear to represent a floor in the achievable performance of CGI in flight.

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Eric Cady, Nicholas Bowman, Alexandra Z. Greenbaum, James G. Ingalls, Brian Kern, John Krist, David Marx, Ilya Poberezhskiy, A J Eldorado Riggs, Garreth Ruane, Byoung-Joon Seo, Fang Shi, Hanying Zhou. 2025-07-31. High-order wavefront sensing and control for the Roman Coronagraph Instrument (CGI): architecture and measured performance. https://doi.org/10.1117/1.jatis.11.2.021408

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