A Review of Daytime Atmospheric Optical Turbulence Profile Detection Technology

Deng, Junhong; Song, Tao; Liu, Yu

doi:10.1016/j.chinastron.2023.06.001

Cited by 4 publications

(2 citation statements)

References 30 publications

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“…Using the star image superposition algorithm based on attitude-related frames proposed in this study, superposed star images were obtained for different numbers of frames n=2, 4,6,8,10,12,14,16,18 as shown in Figure 4, and the SNR of star points in each superposed star image was calculated. Under the same experimental conditions, the algorithm proposed by Yu et al [14] was used to obtain superposed star images, and the SNR of star points in these superposed images was calculated, as presented in Table 2.…”

Section: Experiments On the Star Image Superposition Algorithm Based ...mentioning

confidence: 99%

“…Such intense background radiation during the day severely interferes with the energy of star points, leading to a low SNR in the imagery. This low SNR prevents effective target extraction and centroid positioning, thus affecting the attitude measurements of the star sensors [6]. From this analysis, it is clear that reducing or eliminating the impact of daytime sky background radiation on the energy of star points, and thereby increasing the SNR of star points, is crucial for enabling normal attitude measurements by star sensors during the day.…”

Section: Introductionmentioning

confidence: 99%

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A Multimodal Approach for Attitude Measurement of Near-Earth Daytime Star Sensors

He,

Wei

2024

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When star sensors operate under near-Earth daytime conditions, the intense background radiation from the sky severely interferes with the energy of the star points in the imagery, resulting in a low signal-to-noise ratio (SNR) for the star points. This low SNR hinders target extraction and centroid positioning, thereby affecting the normal attitude measurement of star sensors. Addressing the challenge of attitude measurement under daytime conditions, this study first analyzes the mapping relationship of pixel positions in consecutive frames of star sensor imagery. A star image superposition algorithm based on attitude-related frames is proposed. On this foundation, an attitude measurement method based on star image superposition is employed for measuring the attitude of daytime star sensors. Furthermore, a fitting algorithm for the solar centroid is introduced, and a coarse measurement method based on solar position is applied to determine the optical axis orientation of daytime star sensors, enhancing their robustness in daylight conditions. The algorithm proposed in this study is validated through experiments. The results demonstrate that the multimodal attitude measurement method not only effectively improves the SNR of near-Earth daytime star sensor imagery through star image superposition, ensuring the accuracy of attitude measurements, but also ensures the robustness of attitude measurements through solar centroid fitting.

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Section: Experiments On the Star Image Superposition Algorithm Based ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Multimodal Approach for Attitude Measurement of Near-Earth Daytime Star Sensors

He,

Wei

2024

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A portable S-DIMM developed for preliminary measurement of seeing for Solar Site Survey: Theory and one case study

Duan,

Liu,

Song

et al. 2024

New Astronomy

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Reference optical turbulence characteristics at the Large Solar Vacuum Telescope site

Shikhovtsev

2024

Publications of the Astronomical Society of Japan

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Large ground-based solar telescopes are equipped with adaptive optics systems to correct wavefront distortions induced in the turbulent atmosphere. The design of the adaptive optics system strongly depends on the vertical profiles of the optical turbulence. In particular, the characteristics of the optical turbulence determine the design of tomographic adaptive optics systems, which provide image correction within a wide field of view. In the article, a new method to estimate reference optical turbulence characteristics from Era-5 reanalysis assimilated data is presented. This method is based on the dependence of the air refractive index structure constant $C_n^2$ on the vertical shears of wind speed as well as the outer scale of turbulence L0. The L0 parameter is estimated by minimization of the dispersion between the modeled and measured values of the refractive index structure constant $C_n^2$ within the surface layer. For the first time, parametrization coefficients and reference profiles of optical turbulence averaged for the period 1940–2022 are calculated for the Large Solar Vacuum Telescope (LSVT) site. The calculated optical turbulence profiles are representative; these profiles correspond to typical changes of the measured values of the Fried parameter, the isoplanatic angle, and the outer scale of turbulence at the LSVT site. The model turbulence profiles are verified taking into account the Shack–Hartmann wavefront sensor measurements at the LSVT. The higher accuracy of estimation of the optical turbulence characteristics makes it possible to refine parameters relevant to the LSVT adaptive optics system. The obtained results can be used in order to develop high-resolution solar adaptive optics technologies as applied to ground-based telescopes including those using the principles of atmospheric tomography.

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A Review of Daytime Atmospheric Optical Turbulence Profile Detection Technology

Cited by 4 publications

References 30 publications

A Multimodal Approach for Attitude Measurement of Near-Earth Daytime Star Sensors

A Multimodal Approach for Attitude Measurement of Near-Earth Daytime Star Sensors

A portable S-DIMM developed for preliminary measurement of seeing for Solar Site Survey: Theory and one case study

Reference optical turbulence characteristics at the Large Solar Vacuum Telescope site

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