29 July 2016 Small-grid dithers for the JWST coronagraphs
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Abstract
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, Rémi Soummer, Laurent Pueyo, Dean C. Hines, Edmund P. Nelan, Marshall Perrin, Mark Clampin, 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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