Laboratory Demonstration of Spatial Linear Dark Field Control For Imaging Extrasolar Planets in Reflected Light

Imaging planets in reflected light, a key focus of future NASA missions and ELTs, requires advanced wavefront control to maintain a deep, temporally correlated null of stellar halo -- i.e. a dark hole -- at just several diffraction beam widths. Using the Ames Coronagraph Experiment testbed, we prese...

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Bibliographic Details
Published in:arXiv.org 2020-07
Main Authors: Currie, Thayne, Pluzhnik, Eugene, Guyon, Olivier, Belikov, Ruslan, Miller, Kelsey, Bos, Steven, Males, Jared, Sirbu, Dan, Bond, Charlotte, Frazin, Richard, Groff, Tyler, Kern, Brian, Lozi, Julien, Mazin, Benjamin, Nemati, Bijan, Norris, Barnaby, Subedi, Hari, Scott, Will
Format: Article
Language:English
Subjects:
Coronagraphs
Extrasolar planets
Image enhancement
Laboratories
Laboratory tests
Low mass stars
Space missions
Space telescopes
Wave front control
Wave fronts
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Summary:Imaging planets in reflected light, a key focus of future NASA missions and ELTs, requires advanced wavefront control to maintain a deep, temporally correlated null of stellar halo -- i.e. a dark hole -- at just several diffraction beam widths. Using the Ames Coronagraph Experiment testbed, we present the first laboratory tests of Spatial Linear Dark Field Control (LDFC) approaching raw contrasts (\(\sim\) 5\(\times\)10\(^{-7}\)) and separations (1.5--5.2 \(\lambda\)/D) needed to image jovian planets around Sun-like stars with space-borne coronagraphs like WFIRST-CGI and image exo-Earths around low-mass stars with future ground-based 30m class telescopes. In four separate experiments and for a range of different perturbations, LDFC largely restores (to within a factor of 1.2--1.7) and maintains a dark hole whose contrast is degraded by phase errors by an order of magnitude. Our implementation of classical speckle nulling requires a factor of 2--5 more iterations and 20--50 DM commands to reach contrasts obtained by spatial LDFC. Our results provide a promising path forward to maintaining dark holes without relying on DM probing and in the low-flux regime, which may improve the duty cycle of high-contrast imaging instruments, increase the temporal correlation of speckles, and thus enhance our ability to image true solar system analogues in the next two decades.
ISSN:2331-8422
DOI:10.48550/arxiv.2007.14413