Issue |
A&A
Volume 683, March 2024
|
|
---|---|---|
Article Number | A142 | |
Number of page(s) | 12 | |
Section | Astronomical instrumentation | |
DOI | https://doi.org/10.1051/0004-6361/202347960 | |
Published online | 15 March 2024 |
Extended scene deep-phase-retrieval Shack-Hartmann wavefront sensors
1
Key Laboratory of Adaptive Optics, Chinese Academy of Sciences,
Chengdu
610209, PR China
e-mail: zhangmt@ioe.ac.cn
2
Institute of Optics and Electronics, Chinese Academy of Sciences,
Chengdu
610209, PR China
e-mail: guoyouming@ioe.ac.cn; chrao@ioe.ac.cn
3
The University of Chinese Academy of Sciences,
Beijing
100049, PR China
Received:
14
September
2023
Accepted:
22
January
2024
Context. Strong atmospheric turbulence has been a challenge for high-resolution imaging of solar telescopes. Adaptive optics (AO) systems are capable of improving the quality of imaging by correcting partial aberrations. Thus, the performance of Shack-Hartmann sensors in measuring aberrations generally determines the upper performance bound of AO systems. In solar AO, classic correlation Shack-Hartmann sensors only correct a small number of modal aberrations. Moreover, strong aberrations are difficult to measure stably by correlation Shack-Hartmann. In this context, the improvement in the performance of Shark-Hartmann sensors promises to enable higher-resolution imaging of extended objects for ground-based telescopes or Earth observation.
Aims. We propose a new extended scene deep-phase-retrieval Shack-Hartmann wavefront sensing approach to improve the image quality of solar telescopes. It is capable of achieving high-accuracy measurements of high-spatial-resolution wavefronts on extended scene wavefront sensing. Moreover, it has great generalization when observing unknown objects from different fields of view of the telescope.
Methods. Our proposed approach can extract features resembling the sub-aperture point spread function (PSF) from a Shack-Hartmann sensor image without any prior information. Then a convolutional neural network is used to establish a nonlinear mapping between the feature image and the wavefront modal coefficients. The extracted feature greatly eliminates the shape information of the extended object while maintaining more information related to aberrations. We verified the performance of the proposed method through simulations and experiments.
Results. In the indoor experiment on the ground layer adaptive optics (GLAO) of the 1 m New Vacuum Solar Telescope, compared to the Shack-Hartmann correlation method, the proposed method reduces the correction errors by more than one third. When observing objects from different fields of view in the GLAO that differ from the object in the training data, the relative errors fluctuate within the range of 20% to 26%. The AO system with the proposed wavefront measurement method can obtain higher-resolution focal images of the simulated solar granulation after a round of offline correction. The average latency of the proposed method is about 0.6 ms.
Key words: turbulence / atmospheric effects / instrumentation: adaptive optics / instrumentation: high angular resolution / techniques: high angular resolution / techniques: image processing
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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