Low wind effect on VLT/SPHERE: impact, mitigation strategy, and results

J. Milli; M. Kasper; P. Bourget; C. Pannetier; D. Mouillet; J.-F. Sauvage; C. Reyes; T. Fusco; F. Cantalloube; K. Tristam; Z. Wahhaj; J.-L. Beuzit; J. H. Girard; D. Mawet; A. Telle; A. Vigan; M. N'Diaye

doi:10.1117/12.2311499

10 July 2018 Low wind effect on VLT/SPHERE: impact, mitigation strategy, and results

J. Milli, M. Kasper, P. Bourget, C. Pannetier, D. Mouillet, J.-F. Sauvage, C. Reyes, T. Fusco, F. Cantalloube, K. Tristam, Z. Wahhaj, J.-L. Beuzit, J. H. Girard, D. Mawet, A. Telle, A. Vigan, M. N'Diaye

Author Affiliations +

Proceedings Volume 10703, Adaptive Optics Systems VI; 107032A (2018) https://doi.org/10.1117/12.2311499
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

The low wind effect is a phenomenon disturbing the phase of the wavefront in the pupil of a large telescope obstructed by spiders, in the absence of wind. It can be explained by the radiative cooling of the spiders, creating air temperature inhomogeneities across the pupil. Because it is unseen by traditional adaptive optics (AO) systems, thus uncorrected, it significantly degrades the quality of AO-corrected images. We provide a statistical analysis of the strength of this effect as seen by VLT/SPHERE after 4 years of operations. We analyse its dependence upon the wind and temperature conditions. We describe the mitigation strategy implemented in 2017: a specific coating with low thermal emissivity in the mid-infrared was applied on the spiders of Unit Telescope 3. We quantify the improvement in terms of image quality, contrast and wave front error using both focal plane images and measured phase maps.

Conference Presentation

Citation Download Citation

J. Milli, M. Kasper, P. Bourget, C. Pannetier, D. Mouillet, J.-F. Sauvage, C. Reyes, T. Fusco, F. Cantalloube, K. Tristam, Z. Wahhaj, J.-L. Beuzit, J. H. Girard, D. Mawet, A. Telle, A. Vigan, and M. N'Diaye "Low wind effect on VLT/SPHERE: impact, mitigation strategy, and results", Proc. SPIE 10703, Adaptive Optics Systems VI, 107032A (10 July 2018); https://doi.org/10.1117/12.2311499

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