TY - CONF
T1 - Overview of focal plane wavefront sensors to correct for the low wind effect on SUBARU/SCExAO
AU - Vievard, S.
AU - Bos, S. P.
AU - Cassaing, F.
AU - Ceau, A.
AU - Guyon, O.
AU - Jovanovic, N.
AU - Keller, C. U.
AU - Lozi, J.
AU - Martinache, F.
AU - Mary, D.
AU - Montmerle-Bonnefois, A.
AU - Mugnier, L. M.
AU - N’Diaye, M.
AU - Norris, B.
AU - Sahoo, A.
AU - Sauvage, J. F.
AU - Snik, F.
AU - Wilby, M. J.
AU - Wong, A.
N1 - Funding Information: The development of SCExAO was supported by the Japan Society for the Promotion of Science (Grant-in-Aid for Research #23340051, #26220704, #23103002, #19H00703 & #19H00695), the Astrobiology Center of the National Institutes of Natural Sciences, Japan, the Mt Cuba Foundation and the director’s contingency fund at Subaru Telescope. F. Martinache’s work is supported by the ERC award CoG - 683029. S.V. would also like to thank Julien Milli for the discussions on the Low Wind Effect. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Publisher Copyright: © 2019 AO4ELT 2019 - Proceedings 6th Adaptive Optics for Extremely Large Telescopes. All rights reserved.
PY - 2019
Y1 - 2019
N2 - The Low Wind Effect (LWE) refers to a phenomenon that occurs when the wind speed inside a telescope dome drops below 3m/s creating a temperature gradient near the telescope spider. This produces phase discontinuities in the pupil plane that are not detected by traditional Adaptive Optics (AO) systems such as the pyramid wavefront sensor or the Shack-Hartmann. Considering the pupil as divided in 4 quadrants by regular spiders, the phase discontinuities correspond to piston, tip and tilt aberrations in each quadrant of the pupil. Uncorrected, it strongly decreases the ability of high contrast imaging instruments utilizing coronagraphy to detect exoplanets at small angular separations. Multiple focal plane wavefront sensors are currently being developed and tested on the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument at Subaru Telescope: Among them, the Zernike Asymmetric Pupil (ZAP) wavefront sensor already showed on-sky that it could measure the LWE induced aberrations in focal plane images. The Fast and Furious algorithm, using previous deformable mirror commands as temporal phase diversity, showed in simulations its efficiency to improve the wavefront quality in the presence of LWE. A Neural Network algorithm trained with SCExAO telemetry showed promising PSF prediction on-sky. The Linearized Analytic Phase Diversity (LAPD) algorithm is a solution for multi-aperture cophasing and is studied to correct for the LWE aberrations by considering the Subaru Telescope as a 4 sub-aperture instrument. We present the different algorithms, show the latest results and compare their implementation on SCExAO/SUBARU as real-time wavefront sensors for the LWE compensation.
AB - The Low Wind Effect (LWE) refers to a phenomenon that occurs when the wind speed inside a telescope dome drops below 3m/s creating a temperature gradient near the telescope spider. This produces phase discontinuities in the pupil plane that are not detected by traditional Adaptive Optics (AO) systems such as the pyramid wavefront sensor or the Shack-Hartmann. Considering the pupil as divided in 4 quadrants by regular spiders, the phase discontinuities correspond to piston, tip and tilt aberrations in each quadrant of the pupil. Uncorrected, it strongly decreases the ability of high contrast imaging instruments utilizing coronagraphy to detect exoplanets at small angular separations. Multiple focal plane wavefront sensors are currently being developed and tested on the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument at Subaru Telescope: Among them, the Zernike Asymmetric Pupil (ZAP) wavefront sensor already showed on-sky that it could measure the LWE induced aberrations in focal plane images. The Fast and Furious algorithm, using previous deformable mirror commands as temporal phase diversity, showed in simulations its efficiency to improve the wavefront quality in the presence of LWE. A Neural Network algorithm trained with SCExAO telemetry showed promising PSF prediction on-sky. The Linearized Analytic Phase Diversity (LAPD) algorithm is a solution for multi-aperture cophasing and is studied to correct for the LWE aberrations by considering the Subaru Telescope as a 4 sub-aperture instrument. We present the different algorithms, show the latest results and compare their implementation on SCExAO/SUBARU as real-time wavefront sensors for the LWE compensation.
KW - Coronography
KW - Focal plane wavefront sensing
KW - High contrast imaging
KW - Low wind effect
KW - SCExAO
KW - Spiders
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M3 - Paper
T2 - 6th International Conference on Adaptive Optics for Extremely Large Telescopes, AO4ELT 2019
Y2 - 9 June 2019 through 14 June 2019
ER -