Multi-conjugate solar adaptive optics at the Vacuum Tower Telescope on Tenerife

Lühe, O. von der; Berkefeld, Thomas; Soltau, D.

doi:10.1016/j.crhy.2005.09.007

Cited by 22 publications

(12 citation statements)

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“…The height distribution of turbulence is then determined via tomography. This approach has been demonstrated successfully on several telescopes, e.g., the Vacuum Tower Telescope (VTT) on the Canary Islands [5] and the Dunn Solar Telescope (DST) in New Mexico [6]. The atmospheric turbulence was corrected within roughly 45 arc sec ×45 arc sec compared to 10 arc sec ×10 arc sec for traditional AO systems.…”

Section: A Current Approach To Solar Multiconjugate Adaptive-opticalmentioning

confidence: 98%

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: A Current Approach To Solar Multiconjugate Adaptive-opticalmentioning

confidence: 98%

Layer-oriented adaptive optics for solar telescopes

Kellerer¹

2012

Appl. Opt.

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“…A number of successful on-the-sky MCAO experiments were performed at the DST and at the German VTT (Vacuum Tower Telescope) on the Canary Islands (Berkefeld et al , 2003 ; Langlois et al , 2004 ; Berkefeld et al , 2005 ; von der Lühe et al , 2005 ; Rimmele et al , 2009 ). As an example the KIS MCAO approach is shown in Figure 49 .…”

Section: Future Developmentsmentioning

confidence: 99%

Solar Adaptive Optics

Rimmelé

Mariño

2011

Living Rev. Solar Phys.

106

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Adaptive optics (AO) has become an indispensable tool at ground-based solar telescopes. AO enables the ground-based observer to overcome the adverse effects of atmospheric seeing and obtain diffraction limited observations. Over the last decade adaptive optics systems have been deployed at major ground-based solar telescopes and revitalized ground-based solar astronomy. The relatively small aperture of solar telescopes and the bright source make solar AO possible for visible wavelengths where the majority of solar observations are still performed. Solar AO systems enable diffraction limited observations of the Sun for a significant fraction of the available observing time at ground-based solar telescopes, which often have a larger aperture than equivalent space based observatories, such as HINODE. New ground breaking scientific results have been achieved with solar adaptive optics and this trend continues. New large aperture telescopes are currently being deployed or are under construction. With the aid of solar AO these telescopes will obtain observations of the highly structured and dynamic solar atmosphere with unprecedented resolution. This paper reviews solar adaptive optics techniques and summarizes the recent progress in the field of solar adaptive optics. An outlook to future solar AO developments, including a discussion of Multi-Conjugate AO (MCAO) and Ground-Layer AO (GLAO) will be given.Electronic Supplementary MaterialSupplementary material is available for this article at 10.12942/lrsp-2011-2.

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“…In 2001, Rigaut (Rigaut 2002 proposed the ground layer adaptive optics (GLAO) system in which only one deformable mirror (DM) is used to conjugate with the most intense ground layer turbulence. In GLAO, the multi-direction Shack Hartman wavefront sensor (MD-SHWFS; Langlois et al 2004;von der Lühe et al 2005) is used to detect the distortions from multi-field angles and the wavefront phases are averaged to control the shape of the single low order DM. It is capable of offering a relative, homogeneously improved image quality over a very large FOV.…”

Section: Introductionmentioning

confidence: 99%

Wide field-of-view, high-resolution Solar observation in combination with ground layer adaptive optics and speckle imaging

Zhong

Zhang

Shi

et al. 2020

A&A

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Context. High angular resolution images at a wide field of view are required for investigating Solar physics and predicting space weather. Ground-based observations are often subject to adaptive optics (AO) correction and post-facto reconstruction techniques to improve the spatial resolution. The combination of ground layer adaptive optics (GLAO) and speckle imaging is appealing with regard to a simplification of the correction and the high resolution of the reconstruction. The speckle transfer functions (STFs) used in the speckle image reconstruction mainly determine the photometric accuracy of the recovered result. The STF model proposed by Friedrich Wöger and Oskar von der Lühe in the classical AO condition is generic enough to accommodate the GLAO condition if correct inputs are given. Thus, the precisely calculated inputs to the model STF are essential for the final results. The necessary input for the model STF is the correction efficiency which can be calculated simply with the assumption of one layer turbulence. The method for calculating the correction efficiency for the classical AO condition should also be improved to suit the GLAO condition. The generic average height of the turbulence layer used by Friedrich Wöger and Oskar von der Lühe in the classic AO correction may lead to reduced accuracy and should be revised to improve photometric accuracy. Aims. This study is aimed at obtaining quantitative photometric reconstructed images in the GLAO condition. We propose methods for extracting the appropriate inputs for the STF model. Methods. In this paper, the telemetry data of the GLAO system was used to extract the correction efficiency and the equivalent height of the turbulence. To analyze the photometric accuracy of the method, the influence resulting from the distribution of the atmospheric turbulence profile and the extension of the guide stars are investigated by simulations. At those simulations, we computed the STF from the wavefront phases and convolved it with the high-resolution numerical simulations of the solar photosphere. We then deconvolved them with the model STF calculated from the correction efficiency and the equivalent height to obtain a reconstructed image. To compute the resulting photometric precision, we compared the intensity of the original image with the reconstructed image. We reconstructed the solar images taken by the GLAO prototype system at the New Vacuum Solar Telescope of the Yunnan Astronomical Observatory using this method and analyzed the results. Results. These simulations and ensuing analysis demonstrate that high photometric precision can be obtained for speckle amplitude reconstruction using the inputs for the model STF derived from the telemetry data of the GLAO system.

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Multi-conjugate solar adaptive optics at the Vacuum Tower Telescope on Tenerife

Cited by 22 publications

References 14 publications

Layer-oriented adaptive optics for solar telescopes

Layer-oriented adaptive optics for solar telescopes

Solar Adaptive Optics

Wide field-of-view, high-resolution Solar observation in combination with ground layer adaptive optics and speckle imaging

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