Evaluating the LUVOIR Coronagraph Sensitivity to Telescope Aberrations

Abstract

Direct imaging of exoplanets in their habitable zone is extremely challenging due to two main factors: the proximity of the planet to the parent star and the flux ratio between the planet and the parent star, usually to the order of 10−10in the visible. Future missions like the Large UV-Optical-Infrared (LUVOIR)Surveyor and the Habitable exoplanet Imaging Mission (HabEx) require large apertures and coronagraphs with active wavefront control to be able to suppress the starlight so faint planets can be detected and characterized adjacent to their parent star. The Extreme Coronagraph for Living Planet Systems (ECLIPS) is the coronagraph instrument on the LUVOIR Surveyor mission concept. The Apodized Pupil Lyot Coronagraph (APLC) is one of the baselined mask technologies to enable 10−10 contrast observations in the habitable zones of nearby stars. The LUVOIR concept uses a large, segmented primary mirror (8–15 meters in diameter) to meet its scientific objectives. For such an observatory architecture, the coronagraph performance depends on active wavefront sensing and control and metrology subsystems to compensate for errors in segment alignment (piston and tip/tilt), secondary mirror alignment, and global low-order wavefront errors. For the LUVOIR-A architecture (15m obscured telescope), we evaluate the sensitivity to segment-to-segment tip/tilt, piston, power (focus), astigmatism, coma, trefoil and spherical errors, and to errors induced by misalignment of the secondary mirror. Here we present the latest results of the simulation of these effects and discuss the achieved contrast for exoplanet detection and characterization under these circumstances.