Propagation through Atmospheric Optical Turbulence

Beland, Robert R.

doi:10.1117/3.2543821.ch2

Cited by 50 publications

(24 citation statements)

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“…the signal from monostatic LGS can be used to correct for the "global" tilt of the wavefront in telescopes. Moreover, as estimates show, the magnitude of the measured value of such residual jitter will at least be comparable in magnitude to the LGS signal when using a polychromatic reference star 6 .…”

Section: Analytical and Numerical Calculationsmentioning

confidence: 88%

“…We perform numerical calculations. The model of the turbulence profile of the structural constant of the refractive index of the atmosphere HV 5/7 was used in the calculations 6 . Table 2 shows the results of numerical calculation the magnitude of the signal jitter of the LGS image when working according to the monostatic scheme for different heights of LGS.…”

Section: Analytical and Numerical Calculationsmentioning

confidence: 99%

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The problem of measuring the global tilt from laser guide star

Bolbasova

Лукин²,

Ермаков³

et al. 2022

28th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics

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The random inhomogeneities of the refractive index due to turbulent motion in the atmosphere cause a significant decrease in the theoretical resolution of an optical telescope, cause such well-known effects as scintillation, jitter, and degradation of the optical images. Adaptive optics (AO) systems with a laser guide star (LGS) are designed to eliminate the negative effects. The main limitation of LGS is the problem of measuring the global tilt. We offer the approach to using the LGS signal. The approach, where initially the LGS is considered as a point source of spherical wave with a random center is considered. The results of analytical and numerical calculations are reported. The estimation of sodium column density and height peak of sodium mesospheric layer above large Russian Observatories are presented also.

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Section: Analytical and Numerical Calculationsmentioning

confidence: 88%

Section: Analytical and Numerical Calculationsmentioning

confidence: 99%

The problem of measuring the global tilt from laser guide star

Bolbasova

Лукин²,

Ермаков³

et al. 2022

28th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics

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“…Then, the temperature structure parameter 𝐴𝐴 𝐴𝐴 2 𝑇𝑇 is extracted, similarly to Equation 7. Using the pressure and temperature from the radiosonde observations, the temperature structure parameter is finally converted to the refractive index structure parameter 𝐴𝐴 𝐴𝐴 2 𝑛𝑛 thanks to Beland (1993):…”

Section: Application To T-rex Thermosonde Measurements At Three River...mentioning

confidence: 99%

“…Then, the temperature structure parameter

{C}_{T}^{2}

is extracted, similarly to Equation . Using the pressure and temperature from the radiosonde observations, the temperature structure parameter is finally converted to the refractive index structure parameter

{C}_{n}^{2}

thanks to Beland (1993):

{C}_{n}^{2}\,=\,{\left(\frac{\partial n}{\partial T}\right)}^{2}\,{C}_{T}^{2}\,=\,{\left(79\times 1{0}^{-6}\frac{p}{{T}^{2}}\right)}^{2}\,{C}_{T}^{2},

with p in hectopascal, T in kelvin and the refractive index expression coming from Equation .…”

Section: Validation Of the Cn2 ${C}_{n}^{2}$ Models Through Data Anal...mentioning

confidence: 99%

Computation of Optical Refractive Index Structure Parameter From Its Statistical Definition Using Radiosonde Data

2023

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“…For a slant path, where C n 2 is a function of height, the path-integrated transverse coherence length ρ 0 along the path length L, where L = H⋅sec β with zenith angle β, is given for a spherical wave by 5 : for downward looking case (sensor at height H, source at the ground)…”

Section: Turbulence Modulation Transfer Function Mtf and Point Spread...mentioning

confidence: 99%

Influence of atmospheric turbulence on imaging quality of electro-optical sensors in different climates

Weiss-Wrana

2004

SPIE Proceedings

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During long-term experiments FGAN-FOM measured Cn2 values over land with identical scintillometers in two different climates, in moderate climate in mid-Europe and in arid climate. Since Cn2 usually changes as a function of time-of-day and of season its influence on electro-optical systems can only be expressed in a statistical way. The cumulative frequencies of occurrence were calculated for a time period of one month for different times of the day. The statistical analysis was applied to calculate the effects of atmospheric turbulence on sensor performance like turbulence MTF, the resolution limit due to turbulence and intensity fluctuation. The calculations were performed for a SWIR sensor (active imaging system) and for typical MWIR and LWIR warning sensors. Turbulence MTF were calculated for a slant path of 5 km from the ground to a height of 100 m for upward and downward looking cases. For horizontal paths at a height of 2 m and 30 m the resolution limits due to turbulence were compared with the corresponding diffraction-limited ones. Calculations of the normalized intensity fluctuations were carried out for two slant propagation paths (zenith angle ? = 30° and 80°)

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Propagation through Atmospheric Optical Turbulence

Cited by 50 publications

References 0 publications

The problem of measuring the global tilt from laser guide star

The problem of measuring the global tilt from laser guide star

Computation of Optical Refractive Index Structure Parameter From Its Statistical Definition Using Radiosonde Data

Influence of atmospheric turbulence on imaging quality of electro-optical sensors in different climates

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