Solar Ground-Layer Adaptive Optics

Ren, Deqing; Jolissaint, Laurent; Zhang, Xi; Dou, Jianpei; Chen, Rui; Zhao, Gang; Zhu, Yongtian

doi:10.1086/681672

Cited by 12 publications

(6 citation statements)

References 25 publications

(35 reference statements)

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“…A recent nighttime on-sky experience demonstrated that such a GLAO correction loop is converged and can be effectively used to correct the low altitude turbulence. 18 Solar GLAO was also successfully demonstrated in the NIR 11 as well as in the visible in our recent solar GLAO run with the Dunn solar telescope, in which a FOV on the order of 40 0 0 × 40 0 0 was used for wavefront sensing. It is highly estimated that a better performance should be achievable with an additional DM used to correct the high-altitude turbulence, which can be immediately realized by the proposed PT-MCAO.…”

Section: Discussionmentioning

confidence: 95%

“…As a result, there is no routine operational solar MCAO available now, although progresses are being made for solar MCAO developments. [11][12][13] In this publication, we propose a pupil-transformation MCAO (PT-MCAO) for solar high-resolution imaging over a large FOV. Our PT-MCAO uses a similar hardware configuration with that of the star-oriented MCAO.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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Section: Examples Of the State Of The Art And Current Statusmentioning

confidence: 99%

“…In the near future, these MCAO systems will allow for magnetic field measurements at a higher spatial resolution over a much larger field-of-view than conventional AO systems deliver . Also, recent demonstration of ground-layer solar AO by Ren et al (2015) looks promising. Specialized detectors designed for high speed polarimetry are capable of reaching a polarization sensitivity of the order of 1 × 10 −5 of continuum intensity.…”

Section: Examples Of the State Of The Art And Current Statusmentioning

confidence: 99%

Measurements of Photospheric and Chromospheric Magnetic Fields

et al. 2015

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The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent, their importance for the thermodynamics in the solar photosphere is determined by the total magnetic flux. Whereas in low-flux quiet Sun regions, magnetic structures are shuffled around by the motion of granules, the high-flux areas like sunspots or pores effectively suppress convection, leading to a temperature decrease of up to 3000 K. The importance of magnetic fields to the conditions in higher atmospheric layers, the chromosphere and corona, is indisputable. Magnetic fields in both active and quiet regions are the main coupling agent between the outer layers of the solar atmosphere, and are therefore not only involved in the structuring of these layers, but also for the transport of energy from the solar surface through the corona to the interplanetary space. Consequently, inference of magnetic fields in the photosphere, and especially in the chromosphere, is crucial to deepen our understanding not only for solar phenomena such as chromospheric and coronal heating, flares or coronal mass ejections, but also for fundamental physical topics like dynamo theory or atomic physics. In this review, we present an overview of significant advances during the last decades in measurement techniques, analysis methods, and the availability of observatories, together with some selected results. We discuss the problems of determining magnetic fields at smallest spatial scales, connected with increasing demands on polarimetric sensitivity and temporal resolution, and highlight some promising future developments for their solution.Comment: Accepted for publication in "Space Science Reviews"; 42 pages, 16 figure

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“…GLAO might also be attractive for small synoptic solar telescopes, such as SOLIS or SPRING, because of its potential to provide neardiffraction-limited imaging of the full solar disk for this class of telescopes depending on the seeing characteristics of their sites (Rimmele & Marino 2011). Dedicated solar GLAO experiments without MCAO were performed first at the 76-cm Dunn Solar Telescope (Rimmele et al 2010) in the visible light regime and recently at the McMath-Pierce Solar Telescope and the Dunn Solar Telescope (Ren et al 2015) in the near-infrared H band (1.5−1.8 µm), but a side-by-side comparison of CAO and GLAO observations demonstrating the merit of GLAO for solar observations was lacking.…”

Section: Introductionmentioning

confidence: 99%

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

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et al. 2017

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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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Solar Ground-Layer Adaptive Optics

Cited by 12 publications

References 25 publications

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

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

Measurements of Photospheric and Chromospheric Magnetic Fields

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

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