Investigation of Anisoplanatic Effect in Atmospheric Turbulence Probing with Beacon INumerical Modeling

Xi, 罗曦 Luo; Xinyang, 李新阳 Li

doi:10.3788/cjl201441.0612002

Cited by 2 publications

(1 citation statement)

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“…This causes a dispersion effect, which results in an incomplete correction of the signal light when correcting it according to the beacon light distortion data. A correction residual exists in AO caused by the signal light and the beacon light [11,12].…”

Section: Introductionmentioning

confidence: 99%

Study on the Difference of Wavefront Distortion on Beams Caused by Wavelength Differences in Weak Turbulence Region

Kang

et al. 2023

Photonics

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In dual-wavelength free-space optical communication systems, the wavefront distortion differences caused by the wavelength difference of the signal and beacon lights cannot be completely corrected. In this study, according to the method of geometric optics, the relationship between the wavefront phases of the signal and beacon lights is analyzed by establishing a mathematical model of the cross-correlation ratio of the arrival-angle fluctuation and phase relationship of different Gaussian-beam wavelengths under weak turbulence near the surface. The numerical results show that after Gaussian beams of different wavelengths propagate through the same atmospheric channel, the cross-correlation number of the arrival-angle fluctuation decreases with an increase in the wavelength difference, waist radius, and turbulence intensity, and increases with an increase in propagation distance. The beam-wavefront phase difference increases with an increasing wavelength difference. Finally, a wavefront distortion correction experiment of a dual-wavelength adaptive optical system verified the correctness of the wavefront phase-difference relationship between the signal light and beacon light established in this study.

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Section: Introductionmentioning

confidence: 99%

Study on the Difference of Wavefront Distortion on Beams Caused by Wavelength Differences in Weak Turbulence Region

Kang

et al. 2023

Photonics

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Experimental investigation of angular anisoplanatism for sodium beacon

Xi¹,

Li²,

Shijie³

et al. 2018

Acta Phys. Sin.

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To understand the characteristics of the anisoplanatic error resulting from different return-light experiences between the sodium beacon with a greater angular offset and the science object through atmospheric turbulence, the angular anisoplanatism for sodium beacon is investigated experimentally based on the technique of synchronized range gating. The return-light spot arrays through turbulent atmosphere from the natural star and the sodium beacon with 50 rad angular offsets are synchronously collected by using a single Hartmann wavefront sensor, consequently the synchronous turbulence-induced wavefront distortion sequences are recovered for the on-axis natural star and the off-axis sodium beacon. According to the experimental data, the temporal correlations of the wavefront distributions and decomposed Zernike modes between the on-axis natural star and the off-axis sodium beacon are discussed. By comparing the off-axis sodium beacon with the on-axis natural star, we analyse the statistics of the acquired angular anisoplanatism error and its associated Zernike-modal variances for the off-axis sodium beacon, and derive the Zernike-modal relative anisoplanatic errors as well. Furthermore, the influence of the acquired angular anisoplanatism error on the quality of imaging point spread function (PSF) is studied. The experimental results show that the existence of 50 rad angular deviation between the sodium beacon and the natural star causes that there are a certain correlation between just low-order Zernike modes of these two types of wavefronts (e.g. from the 3rd order to the 9th order), but the correlations between other high-order Zernike modes of these two types of wavefronts are severely degenerated and even these modes are de-correlated, resulting from the improper turbulence probing with off-axis sodium beacon off the ray path from the natural star to the telescope aperture. The angular anisoplanatism error has a great influence on the quality of imaging PSF, which leads to a degradation of Strehl ratio of 0.31-0.22 and beam quality factor of 2.70-3.35. Therefore, the influence may not to be ignored. At the end of this paper, according to the derived experimental turbulence coherence length and the generalized Hufnagel-Valley model, we calculate the theoretical anisoplanatic phase variance for the sodium beacon with 50 rad angular offsets, which is in good accordance with the measured anisoplanatic phase variance. This investigation is useful in promoting our knowledge of sodium beacon angular anisoplanatism effect on turbulence probing.

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Investigation of Anisoplanatic Effect in Atmospheric Turbulence Probing with Beacon INumerical Modeling

Cited by 2 publications

References 0 publications

Study on the Difference of Wavefront Distortion on Beams Caused by Wavelength Differences in Weak Turbulence Region

Study on the Difference of Wavefront Distortion on Beams Caused by Wavelength Differences in Weak Turbulence Region

Experimental investigation of angular anisoplanatism for sodium beacon

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