29 July 2016 Small-grid dithers for the JWST coronagraphs
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We discuss new results of coronagraphic simulations demonstrating a novel mode for JWST that utilizes sub-pixel dithered reference images, called Small-Grid Dithers, to optimize coronagraphic PSF subtraction. These sub-pixel dithers are executed with the Fine Steering Mirror under fine guidance, are accurate to ~2-3 milliarcseconds (1-σ/axis), and provide ample speckle diversity to reconstruct an optimized synthetic reference PSF using LOCI or KLIP. We also discuss the performance gains of Small-Grid Dithers compared to the standard undithered scenario, and show potential contrast gain factors for the NIRCam and MIRI coronagraphs ranging from 2 to more than 10, respectively.
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Charles-Philippe Lajoie, Charles-Philippe Lajoie, Rémi Soummer, Rémi Soummer, Laurent Pueyo, Laurent Pueyo, Dean C. Hines, Dean C. Hines, Edmund P. Nelan, Edmund P. Nelan, Marshall Perrin, Marshall Perrin, Mark Clampin, Mark Clampin, John C. Isaacs, John C. Isaacs, "Small-grid dithers for the JWST coronagraphs", Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 99045K (29 July 2016); doi: 10.1117/12.2233032; https://doi.org/10.1117/12.2233032

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