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NASA NTRS · 20170002252

Small-Grid Dithers for the JWST Coronagraphs

Lajoie, Charles-Philippe·Soummer, Remi·Pueyo, Laurent·Hines, Dean C.·Nelan, Edmund P.·Perrin, Marshall·Clampin, Mark·Isaacs, John C.
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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 approx.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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Lajoie, Charles-Philippe, Soummer, Remi, Pueyo, Laurent, Hines, Dean C., Nelan, Edmund P., Perrin, Marshall, Clampin, Mark, Isaacs, John C.. 2016-07-29. Small-Grid Dithers for the JWST Coronagraphs. https://ntrs.nasa.gov/citations/20170002252

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