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Demonstrating predictive wavefront control with the Keck II near-infrared pyramid wavefront sensor
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Paper Abstract

The success of ground-based instruments for high contrast exoplanet imaging depends on the degree to which adaptive optics (AO) systems can mitigate atmospheric turbulence. While modern AO systems typically suffer from millisecond time lags between wavefront measurement and control, predictive wavefront control (pWFC) is a means of compensating for those time lags using previous wavefront measurements, thereby improving the raw contrast in the post-coronagraphic science focal plane. A method of predictive control based on Empirical Orthogonal Functions (EOF) has previously been proposed and demonstrated on Subaru/SCExAO. In this paper we present initial tests of this method for application to the near-infrared pyramid wavefront sensor (PYWFS) recently installed in the Keck II AO system. We demonstrate the expected root-mean-square (RMS) wavefront error and contrast benefits of pWFC based on simulations, applying pWFC to on-sky telemetry data saved during commissioning of the PYWFS. We discuss how the performance varies as different temporal and spatial scales are included in the computation of the predictive filter. We further describe the implementation of EOF pWFC within the PYWFS dedicated real-time controller (RTC), and, via daytime testing at the observatory, we demonstrate the performance of pWFC in real time when pre-computed phase screens are applied to the deformable mirror (DM).

Paper Details

Date Published: 9 September 2019
PDF: 10 pages
Proc. SPIE 11117, Techniques and Instrumentation for Detection of Exoplanets IX, 111170W (9 September 2019); doi: 10.1117/12.2529687
Show Author Affiliations
Rebecca Jensen-Clem, Univ. of California, Berkeley (United States)
Charlotte Z. Bond, W. M. Keck Observatory (United States)
Sylvain Cetre, W. M. Keck Observatory (United States)
Eden McEwen, Univ. of California, Berkeley (United States)
Peter Wizinowich, W. M. Keck Observatory (United States)
Sam Ragland, W. M. Keck Observatory (United States)
Dimitri Mawet, Caltech (United States)
James Graham, Univ. of California, Berkeley (United States)


Published in SPIE Proceedings Vol. 11117:
Techniques and Instrumentation for Detection of Exoplanets IX
Stuart B. Shaklan, Editor(s)

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