4 August 2016 Recent developments with the visible nulling coronagraph
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Abstract
A wide array of general astrophysics studies including detecting and characterizing habitable exoplanets could be enabled by a future large segmented telescope with sensitivity in the UV, optical, and infrared bands. When paired with a starshade or coronagraph, such an observatory could enable direct imaging and detailed spectroscopic observations of nearby Earth-like habitable zone planets. Over the past several years, a laboratory-based Visible Nulling Coronagraph (VNC) has evolved to reach requisite contrasts over a ~ 1 nm bandwidth at narrow source angle separation using a segmented deformable mirror in one arm of a Mach-Zehnder layout. More recent efforts targeted broadband performance following the addition of two sets of half-wave Fresnel rhomb achromatic phase shifters (APS) with the goal of reaching 10-9 contrast, at a separation of 2λ/D, using a 40 nm (6%) bandwidth single mode fiber source. Here we present updates on the VNC broadband nulling effort, including approaches to addressing system contrast limitations.
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Brian A. Hicks, Richard G. Lyon, Matthew R. Bolcar, Mark Clampin, Peter Petrone, Michael A. Helmbrecht, Joseph M. Howard, Ian J. Miller, "Recent developments with the visible nulling coronagraph", Proc. SPIE 9907, Optical and Infrared Interferometry and Imaging V, 99072O (4 August 2016); doi: 10.1117/12.2234315; https://doi.org/10.1117/12.2234315
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