Profiles of the daytime atmospheric turbulence above Big Bear solar observatory

Kellerer, Aglae; Gorceix, Nicolas; Mariño, José María Solé; Cao, Wenda; Goode, Philip R.

doi:10.1051/0004-6361/201218844

Cited by 35 publications

(31 citation statements)

References 15 publications

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“…The parameter values for GREGOR and EST are taken from Berkefeld et al [7,21]. The values for NST were determined from profiles of the atmospheric turbulence [22]. All three systems use the star-oriented approach inside a 60 arc sec ×60 arc sec field.…”

Section: Resultsmentioning

confidence: 99%

Layer-oriented adaptive optics for solar telescopes

Kellerer¹

2012

Appl. Opt.

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with the permission of OSA. The paper can be found at the following URL on the OSA website:http://dx.doi.org/10.1364/AO.51.005743. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. First multiconjugate adaptive-optical (MCAO) systems are currently being installed on solar telescopes. The aim of these systems is to increase the corrected field of view with respect to conventional adaptive optics. However, this first generation is based on a star-oriented approach, and it is then difficult to increase the size of the field of view beyond 60-80 arc sec in diameter. We propose to implement the layeroriented approach in solar MCAO systems by use of wide-field Shack-Hartmann wavefront sensors conjugated to the strongest turbulent layers. The wavefront distortions are averaged over a wide field: the signal from distant turbulence is attenuated and the tomographic reconstruction is thus done optically. The system consists of independent correction loops, which only need to account for local turbulence: the subapertures can be enlarged and the correction frequency reduced. Most importantly, a star-oriented MCAO system becomes more complex with increasing field size, while the layer-oriented approach benefits from larger fields and will therefore be an attractive solution for the future generation of solar MCAO systems.

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Section: Resultsmentioning

confidence: 99%

Layer-oriented adaptive optics for solar telescopes

Kellerer¹

2012

Appl. Opt.

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“…Clear features three identical 357-actuator DMs, two of which are dedicated to highaltitude seeing, and the third always being located in a pupil image. Because turbulence profiling experiments revealed significant turbulence within the first 7−8 km above the telescope with relative weightings varying from day to day (Kellerer et al 2012), the two high-altitude DMs can be flexibly conjugated between about 2 and 8 km on the telescope's line of sight. (The subtropical jet stream at higher altitudes that only occasionally hinders observations in Big Bear is not targeted with Clear at this point.)…”

Section: Clear the Solar Mcao Pathfinder On The Nstmentioning

confidence: 99%

Clearwidens the field for observations of the Sun with multi-conjugate adaptive optics

Schmidt

Gorceix

Goode

et al. 2017

A&A

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The multi-conjugate adaptive optics (MCAO) pathfinder Clear on the New Solar Telescope in Big Bear Lake has provided the first-ever MCAO-corrected observations of the Sun that show a clearly and visibly widened corrected field of view compared to quasisimultaneous observations with classical adaptive optics (CAO) correction. Clear simultaneously uses three deformable mirrors, each conjugated to a different altitude, to compensate for atmospheric turbulence. While the MCAO correction was most effective over an angle that is approximately three times wider than the angle that was corrected by CAO, the full 53 field of view did benefit from MCAO correction. We further demonstrate that ground-layer-only correction is attractive for solar observations as a complementary flavor of adaptive optics for observational programs that require homogenous seeing improvement over a wide field rather than diffraction-limited resolution. We show illustrative images of solar granulation and of a sunspot obtained on different days in July 2016, and present a brief quantitative analysis of the generalized Fried parameters of the images.

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“…The telescope aperture has an aperture diameter of 1.6 m, which is the same with that of the NST located on the Big Bear Solar Observatory (BBSO). We use the seeing profile measured data from the BBSO, with the seeing Fried parameter of 160, 310, 480, and 1260 mm at the height of 0.2, 1.0, 3.0, and 8.0 km, respectively, at good seeing condition, 16 and this is the only available daytime seeing profile measurement data on a major solar observatory.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Pupil-transformation multiconjugate adaptive optics for solar high-resolution imaging

et al. 2016

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Abstract. We propose a multiconjugate adaptive optics (MCAO) system called pupil-transformation MCAO (PT-MCAO) for solar high-angular resolution imaging over a large field of view. The PT-MCAO, consisting of two deformable mirrors (DMs), uses a Shack-Hartmann wavefront sensor located on the telescope pupil to measure the wavefront slopes from several guide stars. The average slopes are used to control the first DM conjugated on the telescope aperture by a solar ground-layer adaptive optics (AO) approach while the remaining slopes are used to control the second DM conjugated on a high altitude by a conventional solar AO via a geometric PT. The PT-MCAO uses a similar hardware configuration as the conventional star-oriented MCAO. However, a distinctive feature of our PT-MCAO is that it avoids the construction of tomography wavefront, which is a time-consuming and complex process for the solar real-time atmospheric turbulence correction. For the PT-MCAO, current widely used and fully understood conventional solar AO closed-loop control algorithms can be directly used to control the two DMs, which greatly reduces the real-time calculation power requirement and makes the PT-MCAO easy to implement. In this publication, we discuss the PT-MCAO methodology, its unique features, and compare its performance with that of the conventional solar star-oriented MCAO systems, which demonstrate that the PT-MCAO can be immediately used for solar high-resolution imaging.

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Profiles of the daytime atmospheric turbulence above Big Bear solar observatory

Cited by 35 publications

References 15 publications

Layer-oriented adaptive optics for solar telescopes

Layer-oriented adaptive optics for solar telescopes

Clearwidens the field for observations of the Sun with multi-conjugate adaptive optics

Pupil-transformation multiconjugate adaptive optics for solar high-resolution imaging

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