Small-grid dithers for the JWST coronagraphs

Charles-Philippe Lajoie; Rémi Soummer; Laurent Pueyo; Dean C. Hines; Edmund P. Nelan; Marshall Perrin; Mark Clampin; John C. Isaacs III

doi:10.1117/12.2233032

29 July 2016 Small-grid dithers for the JWST coronagraphs

Charles-Philippe Lajoie, Rémi Soummer, Laurent Pueyo, Dean C. Hines, Edmund P. Nelan, Marshall Perrin, Mark Clampin, John C. Isaacs III

Author Affiliations +

Proceedings Volume 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave; 99045K (2016) https://doi.org/10.1117/12.2233032
Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom

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, and John C. Isaacs III "Small-grid dithers for the JWST coronagraphs", Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 99045K (29 July 2016); https://doi.org/10.1117/12.2233032

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