Asymmetries in adaptive optics point spread functions
Abstract
An explanation for the origin of asymmetry along the preferential axis of the 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 towards 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.
Cite
@article{arxiv.1909.12981,
title = {Asymmetries in adaptive optics point spread functions},
author = {Alexander Madurowicz and Bruce Macintosh and Vanessa P. Bailey and Jeffrey Chilcote and Marshall Perrin and Lisa Poyneer and Laurent Pueyo and Jean-Baptiste Ruffio and Travis Barman and Joanna Bulger and Tara Cotten and Robert J. De Rosa and Rene Doyon and Gaspard Duchêne and Thomas M. Esposito and Michael P. Fitzgerald and Katherine B. Follette and Benjamin L. Gerard and Stephen J. Goodsell and James R. Graham and Alexandra Z. Greenbaum and Pascale Hibon and Li-Wei Hung and Patrick Ingraham and Paul Kalas and Quinn Konopacky and Jérôme Maire and Franck Marchis and Mark S. Marley and Christian Marois and Stanimir Metchev and Maxwell A. Millar-Blanchaer and Eric L. Nielsen and Rebecca Oppenheimer and David Palmer and Jennifer Patience and Abhijith Rajan and Julien Rameau and Fredrik T. Rantakyrö and Dmitry Savransky and Anand Sivaramakrishnan and Inseok Song and Remi Soummer and Melissa Tallis and Sandrine Thomas and Jason J. Wang and Kimberly Ward-Duong and Schuyler Wolf},
journal= {arXiv preprint arXiv:1909.12981},
year = {2019}
}
Comments
28 Pages, 13 Figures, Accepted to JATIS