scholarly journals Method of Estimation of Turbulence Integral Parameters

2021 ◽  
Vol 11 (9) ◽  
pp. 4157
Author(s):  
Hong Shen ◽  
Longkun Yu ◽  
Xu Jing ◽  
Fengfu Tan
Keyword(s):  
Refractive Index ◽  
Linear Combination ◽  
Adaptive Optics ◽  
Structure Constant ◽  
Index Structure ◽  
Angle Of Arrival ◽  
Weighting Functions ◽  
Optical Effects ◽  
Finite Distance ◽  
Turbulence Parameters

The optical effects of turbulence are directly related to turbulence integral parameters, which are integrals of the refractive index structure constant over a whole path with different path-weighting functions (PWFs). We describe a method that utilizes measurable turbulence integral parameters, such as angle-of-arrival fluctuations and scintillation, to estimate turbulence integral parameters that cannot be measured directly. The estimates of the turbulence integral parameters are based on the linear combination of the PWFs of those measurable quantities. New measurable quantities and their PWFs under different propagation conditions were studied. Some interesting and meaningful results have been obtained. This method shows the prospect of characterizing anisoplanatism in adaptive optics and allows for the estimation of some optical turbulence parameters under non-ideal conditions, such as an isoplanatic angle in a finite distance.

Comparison of Refractive Index Structure Constant Deduced from Angle of Arrival Fluctuation and Scintillation Effects

2015 ◽  
Vol 35 (s1) ◽  
pp. s101003
Author(s):  
宋卢军 Song Lujun ◽  
倪小龙 Ni Xiaolong ◽  
刘艺 Liu Yi ◽  
刘智 Liu Zhi
Keyword(s):  
Refractive Index ◽  
Structure Constant ◽  
Index Structure ◽  
Angle Of Arrival

scholarly journals Method for Measuring the Second-Order Moment of Atmospheric Turbulence

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 564
Author(s):  
Hong Shen ◽  
Longkun Yu ◽  
Xu Jing ◽  
Fengfu Tan
Keyword(s):  
Atmospheric Turbulence ◽  
Weighting Function ◽  
Structure Constant ◽  
Turbulence Models ◽  
Second Order ◽  
Index Structure ◽  
Order Moment ◽  
Site Testing ◽  
Optical Effects ◽  
Novel Method

The turbulence moment of order m (μm) is defined as the refractive index structure constant Cn2 integrated over the whole path z with path-weighting function zm. Optical effects of atmospheric turbulence are directly related to turbulence moments. To evaluate the optical effects of atmospheric turbulence, it is necessary to measure the turbulence moment. It is well known that zero-order moments of turbulence (μ0) and five-thirds-order moments of turbulence (μ5/3), which correspond to the seeing and the isoplanatic angles, respectively, have been monitored as routine parameters in astronomical site testing. However, the direct measurement of second-order moments of turbulence (μ2) of the whole layer atmosphere has not been reported. Using a star as the light source, it has been found that μ2 can be measured through the covariance of the irradiance in two receiver apertures with suitable aperture size and aperture separation. Numerical results show that the theoretical error of this novel method is negligible in all the typical turbulence models. This method enabled us to monitor μ2 as a routine parameter in astronomical site testing, which is helpful to understand the characteristics of atmospheric turbulence better combined with μ0 and μ5/3.

Estimating refractive index structure constant and extinction coefficient under misalignment

Optik ◽  
2020 ◽  
Vol 206 ◽  
pp. 164182
Author(s):  
Dagang Jiang ◽  
Ting Lyu ◽  
Xin Liu ◽  
Yishuai Yuan ◽  
Bin Zhu
Keyword(s):  
Refractive Index ◽  
Extinction Coefficient ◽  
Structure Constant ◽  
Index Structure

scholarly journals Equivalent refractive-index structure constant of non-Kolmogorov turbulence

2015 ◽  
Vol 23 (18) ◽  
pp. 23004 ◽  
Author(s):  
Yujie Li ◽  
Wenyue Zhu ◽  
Xiaoqing Wu ◽  
Ruizhong Rao
Keyword(s):  
Refractive Index ◽  
Structure Constant ◽  
Index Structure ◽  
Kolmogorov Turbulence
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