Vortex coronagraph: revisiting the phase retrieval properties via Zernike analysis

Fuente: arXiv
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Autores principales: de Xivry, Gilles Orban, Absil, Olivier
Formato: Preprint
Publicado: 2024
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author de Xivry, Gilles Orban
Absil, Olivier
author_facet de Xivry, Gilles Orban
Absil, Olivier
contents High contrast imaging (HCI) is fundamentally limited by wavefront aberrations, and the ability to perform wavefront sensing from focal plane images is key to reach the full potential of ground and space-based instruments. Vortex focal plane mask coupled with downstream pupil (Lyot) stop stands as one of the best small-angle coronagraphs, but is also sensitive to low-order aberrations. Here, we revisit the behavior of the vortex phase mask, from entrance pupil down to the final detector plane, with Zernike polynomials as input phase aberrations. In particular we develop a second-order expansion that allows us to analyze the phase retrieval properties in a more intuitive and accurate way than previously proposed. With this formalism, we show how the azimuthal vortex modulation modifies the phase retrieval properties compared to normal imaging. In particular, our results suggest that images obtained with a scalar vortex coronagraph can be used for unambiguous focal-plane wavefront sensing in any practical situation. We compare our results with numerical simulations and discuss practical implementation in coronagraphic instruments.
format Preprint
id arxiv_https___arxiv_org_abs_2407_14404
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Vortex coronagraph: revisiting the phase retrieval properties via Zernike analysis
de Xivry, Gilles Orban
Absil, Olivier
Instrumentation and Methods for Astrophysics
Optics
High contrast imaging (HCI) is fundamentally limited by wavefront aberrations, and the ability to perform wavefront sensing from focal plane images is key to reach the full potential of ground and space-based instruments. Vortex focal plane mask coupled with downstream pupil (Lyot) stop stands as one of the best small-angle coronagraphs, but is also sensitive to low-order aberrations. Here, we revisit the behavior of the vortex phase mask, from entrance pupil down to the final detector plane, with Zernike polynomials as input phase aberrations. In particular we develop a second-order expansion that allows us to analyze the phase retrieval properties in a more intuitive and accurate way than previously proposed. With this formalism, we show how the azimuthal vortex modulation modifies the phase retrieval properties compared to normal imaging. In particular, our results suggest that images obtained with a scalar vortex coronagraph can be used for unambiguous focal-plane wavefront sensing in any practical situation. We compare our results with numerical simulations and discuss practical implementation in coronagraphic instruments.
title Vortex coronagraph: revisiting the phase retrieval properties via Zernike analysis
topic Instrumentation and Methods for Astrophysics
Optics
url https://arxiv.org/abs/2407.14404