A "Fast and Furious'" solution to the low-wind effect for SPHERE at the VLT

M. J. Wilby; C. U. Keller; J.-F. Sauvage; T. Fusco; D. Mouillet; J.-L. Beuzit; K. Dohlen

doi:10.1117/12.2233462

27 July 2016 A "Fast and Furious'" solution to the low-wind effect for SPHERE at the VLT

M. J. Wilby, C. U. Keller, J.-F. Sauvage, T. Fusco, D. Mouillet, J.-L. Beuzit, K. Dohlen

Proceedings Volume 9909, Adaptive Optics Systems V; 99096C (2016) https://doi.org/10.1117/12.2233462
Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom

Abstract

We present a potential non-invasive solution to sensing the so-called low-wind effect (LWE) seen in the SPHERE instrument at the VLT, based on the "Fast and Furious (F&F) sequential phase diversity wavefront reconstruction algorithm. This uses non-coronagraphic focal-plane images available from the near-infra-red Differential Tip-Tilt Sensor (DTTS), with the closed-loop correction cycle itself providing the necessary phase diversity between frames required to reconstruct the full wavefront phase. Crucially, this means F&F does not need to apply large artificial phase probes as required by standard phase diversity algorithms, allowing it to operate in a real-time (∼10 Hz) correction mode without impacting science observations. In this paper we present the results of realistic closed-loop AO simulations designed to emulate SPHERE/DTTS observations of the LWE. With this we demonstrate that the F&F algorithm is capable of effective removal of the characteristic point-spread function (PSF) aberrations of strongly LWE-affected images within a few closed-loop iterations, with the final wavefront quality limited only by the corrective order of the deformable mirror. The ultimate goal of this project is to provide an independent, real-time and focal-plane wavefront sensor for SPHERE which is capable of detecting and directly compensating the LWE as it arises, thus improving coronagraph performance under the best 15–20 % of observing conditions where the effect is most pronounced.

Citation Download Citation

M. J. Wilby, C. U. Keller, J.-F. Sauvage, T. Fusco, D. Mouillet, J.-L. Beuzit, and K. Dohlen "A "Fast and Furious'" solution to the low-wind effect for SPHERE at the VLT", Proc. SPIE 9909, Adaptive Optics Systems V, 99096C (27 July 2016); https://doi.org/10.1117/12.2233462

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available