TY - JOUR
T1 - Asymmetries in adaptive optics point spread functions
AU - Madurowicz, Alexander
AU - Macintosh, Bruce
AU - Chilcote, Jeffrey
AU - Perrin, Marshall
AU - Poyneer, Lisa
AU - Pueyo, Laurent
AU - Ruffio, Jean Baptiste
AU - Bailey, Vanessa P.
AU - Barman, Travis
AU - Bulger, Joanna
AU - Cotten, Tara
AU - De Rosa, Robert J.
AU - Doyon, Rene
AU - Duchêne, Gaspard
AU - Esposito, Thomas M.
AU - Fitzgerald, Michael P.
AU - Follette, Katherine B.
AU - Gerard, Benjamin L.
AU - Goodsell, Stephen J.
AU - Graham, James R.
AU - Greenbaum, Alexandra Z.
AU - Hibon, Pascale
AU - Hung, Li Wei
AU - Ingraham, Patrick
AU - Kalas, Paul
AU - Konopacky, Quinn
AU - Maire, Jérôme
AU - Marchis, Franck
AU - Marley, Mark S.
AU - Marois, Christian
AU - Metchev, Stanimir
AU - Millar-Blanchaer, Maxwell A.
AU - Nielsen, Eric L.
AU - Oppenheimer, Rebecca
AU - Palmer, David
AU - Patience, Jennifer
AU - Rajan, Abhijith
AU - Rameau, Julien
AU - Rantakyrö, Fredrik T.
AU - Savransky, Dmitry
AU - Sivaramakrishnan, Anand
AU - Song, Inseok
AU - Soummer, Remi
AU - Tallis, Melissa
AU - Thomas, Sandrine
AU - Wang, Jason J.
AU - Ward-Duong, Kimberly
AU - Wolff, Schuyler
N1 - Publisher Copyright:
© The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
PY - 2019/10/1
Y1 - 2019/10/1
N2 - An explanation for the origin of asymmetry along the preferential axis of the point spread function (PSF) of an AO system is developed. When phase errors from high-altitude turbulence scintillate due to Fresnel propagation, wavefront amplitude errors may be spatially offset from residual phase errors. These correlated errors appear as asymmetry in the image plane under the Fraunhofer condition. In an analytic model with an open-loop AO system, the strength of the asymmetry is calculated for a single mode of phase aberration, which generalizes to two dimensions under a Fourier decomposition of the complex illumination. Other parameters included are the spatial offset of the AO correction, which is the wind velocity in the frozen flow regime multiplied by the effective AO time delay and propagation distance or altitude of the turbulent layer. In this model, the asymmetry is strongest when the wind is slow and nearest to the coronagraphic mask when the turbulent layer is far away, such as when the telescope is pointing low toward the horizon. A great emphasis is made about the fact that the brighter asymmetric lobe of the PSF points in the opposite direction as the wind, which is consistent analytically with the clarification that the image plane electric field distribution is actually the inverse Fourier transform of the aperture plane. Validation of this understanding is made with observations taken from the Gemini Planet Imager, as well as being reproducible in end-to-end AO simulations.
AB - An explanation for the origin of asymmetry along the preferential axis of the point spread function (PSF) of an AO system is developed. When phase errors from high-altitude turbulence scintillate due to Fresnel propagation, wavefront amplitude errors may be spatially offset from residual phase errors. These correlated errors appear as asymmetry in the image plane under the Fraunhofer condition. In an analytic model with an open-loop AO system, the strength of the asymmetry is calculated for a single mode of phase aberration, which generalizes to two dimensions under a Fourier decomposition of the complex illumination. Other parameters included are the spatial offset of the AO correction, which is the wind velocity in the frozen flow regime multiplied by the effective AO time delay and propagation distance or altitude of the turbulent layer. In this model, the asymmetry is strongest when the wind is slow and nearest to the coronagraphic mask when the turbulent layer is far away, such as when the telescope is pointing low toward the horizon. A great emphasis is made about the fact that the brighter asymmetric lobe of the PSF points in the opposite direction as the wind, which is consistent analytically with the clarification that the image plane electric field distribution is actually the inverse Fourier transform of the aperture plane. Validation of this understanding is made with observations taken from the Gemini Planet Imager, as well as being reproducible in end-to-end AO simulations.
KW - Adaptive optics
KW - Fresnel propagation
KW - Point-spread functions
KW - Scintillation
KW - Turbulence
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U2 - 10.1117/1.JATIS.5.4.049003
DO - 10.1117/1.JATIS.5.4.049003
M3 - Article
AN - SCOPUS:85074558777
SN - 2329-4124
VL - 5
JO - Journal of Astronomical Telescopes, Instruments, and Systems
JF - Journal of Astronomical Telescopes, Instruments, and Systems
IS - 4
M1 - 049003
ER -