Point spread function reconstruction simulations for laser guide star multi-conjugate adaptive optics on extremely large telescopes

Gilles, Luc; Wang, Lianqi; Boyer, Corinne

doi:10.1117/12.2315793

Cited by 6 publications

(3 citation statements)

References 7 publications

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“…An alternative to the direct measurement of the PSF is to predict it by modelling the optical system and the atmospheric turbulence using the technique of PSF-reconstruction. 22,23 While this approach has been proved both in theory and on sky, [24][25][26][27] it has not been used consistently for scientific observations. Furthermore, the off-axis variations of the PSF are not predicted and must be modeled.…”

Section: Introductionmentioning

confidence: 99%

AIROPA III: Testing Simulated and On-Sky Data

Turri¹,

Lu²,

Witzel³

et al. 2022

Preprint

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Adaptive optics images from the W. M. Keck Observatory have delivered numerous influential scientific results, including detection of multi-system asteroids, the supermassive black hole at the center of the Milky Way, and directly imaged exoplanets. Specifically, the precise and accurate astrometry these images yield was used to measure the mass of the supermassive black hole using orbits of the surrounding star cluster. Despite these successes, one of the major obstacles to improved astrometric measurements is the spatial and temporal variability of the point-spread function delivered by the instruments. AIROPA is a software package for the astrometric and photometric analysis of adaptive optics images using point-spread function fitting together with the technique of point-spread function reconstruction. In adaptive optics point-spread function reconstruction, the knowledge of the instrument performance and of the atmospheric turbulence is used to predict the long-exposure point-spread function of an observation. In this paper we present the results of our tests using AIROPA on both simulated and on-sky images of the Galactic Center. We find that our method is very reliable in accounting for the static aberrations internal to the instrument, but it does not improve significantly the accuracy on sky, possibly due to uncalibrated telescope aberrations.

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Section: Introductionmentioning

confidence: 99%

AIROPA III: Testing Simulated and On-Sky Data

Turri¹,

Lu²,

Witzel³

et al. 2022

Preprint

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show abstract

“…These algorithms all suffer from anisoplanatism, which is accounted for in [4, 1,2]. Please note that all the mentioned methods -with the exception of [11,12] were designed for Single Conjugate Adaptive Optics systems (SCAO) only. Some of the algorithms were already successfully tested on sky on various telescopes [16,15,9,5].…”

Section: Introductionmentioning

confidence: 99%

“…In the past, several methods have been proposed for PSF reconstruction (see, e.g., [32]). E.g., the methods in [11,12] rely on WFS data only and take global basis functions for the reconstruction. The method proposed in [17] tries to model the phase power spectrum analytically, and in [8] a maximum likelihood approach for the used covariance matrices is taken.…”

Section: Introductionmentioning

confidence: 99%

Point spread function reconstruction for single-conjugate adaptive optics on extremely large telescopes

Wagner¹,

Hofer

Ramlau

2018

J. Astron. Telesc. Instrum. Syst.

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Modern Giant Segmented Mirror Telescopes (GSMTs) like the Extremely Large Telescope, which is currently under construction, depend heavily on Adaptive Optics (AO) systems to correct for atmospheric distortions. However, a residual blur always remains in the astronomical images corrected by Single Conjugate AO (SCAO) systems due to fitting and bandwidth errors, which can mathematically be described by a convolution of the true image with a point spread function (PSF). Due to the nature of the turbulent atmosphere and its correction, the PSF is spatially varying, which is known as aniosplanatic effect. The PSF serves, e.g., as a quality measure for the science images and therefore needs to be known as accurately as possible.In this paper, we present an algorithm for PSF reconstruction in directions apart from the guide star direction in an SCAO system adapted to the needs of GSMTs focused on estimating the contribution of the anisoplanatic and generalized fitting error to the PSF. In particular, the PSF reconstruction algorithm for Single Conjugate Adaptive Optics from [24] is combined with an algorithm for time-dependent atmospheric tomography from [21] to obtain a direction dependent reconstruction of the post-AO PSF.Results obtained in an end-to-end simulation tool show a qualitatively good reconstruction of the PSF compared to the PSF calculated directly from the simulated incoming wavefront as well as a stable performance with respect to imprecise knowledge of atmospheric parameters.

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Demonstration of an imaging technique for the measurement of PSF elongation caused by Atmospheric Dispersion

Born

Jellema

Dijkstra

2022

Monthly Notices of the Royal Astronomical Society

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Elongation of the point spread function due to atmospheric dispersion becomes a severe problem for high resolution imaging instruments, if an atmospheric dispersion corrector is not present. In this work we report on a novel technique to measure this elongation, corrected or uncorrected, from imaging data. By employing a simple diffraction mask it is possible to magnify the chromatic elongation caused by the atmosphere and thus make it easier to measure. We discuss the theory and design of such a mask and report on two proof of concept observations using the 40 cm Gratama telescope at the University of Groningen. We evaluate the acquired images using a geometric approach, a forward modelling approach and from a direct measurement of the length of the point spread function. For the first two methods we report measurements consistent with atmospheric dispersion models to within 0.5 arcsec. Direct measurements of the elongation do not prove suitable for the characterisation of atmospheric dispersion. We conclude that the addition of this type of diffraction mask can be valuable for measurements of PSF elongation. This can enable high precision correction of atmospheric dispersion on future instruments.

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Point spread function reconstruction simulations for laser guide star multi-conjugate adaptive optics on extremely large telescopes

Cited by 6 publications

References 7 publications

AIROPA III: Testing Simulated and On-Sky Data

AIROPA III: Testing Simulated and On-Sky Data

Point spread function reconstruction for single-conjugate adaptive optics on extremely large telescopes

Demonstration of an imaging technique for the measurement of PSF elongation caused by Atmospheric Dispersion

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