Research on Beam Expansion Characteristic of Supercontinuum Laser in Atmospheric Turbulence

Exploring the behavior of supercontinuum laser sources in atmospheric turbulence

Laser Communication and Propagation through the Atmosphere and Oceans IX ◽

10.1117/12.2570399 ◽

2020 ◽

Author(s):

Joseph T. Coffaro ◽

Bruce Berry ◽

Matthew Salfer-Hobbs ◽

Ronald L. Philips ◽

Larry C. Andrews ◽

...

Keyword(s):

Atmospheric Turbulence ◽

Laser Sources ◽

Supercontinuum Laser

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Supercontinuum laser-based monochromatic radiant source for detector spectral responsivity characterization in the range 0.9–1.6 μm using absolute cryogenic radiometer

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-11-28-33 ◽

2020 ◽

pp. 28-33

Author(s):

A. Yu. Dunaev ◽

A. S. Baturin ◽

V. N. Krutikov ◽

S. P. Morozova

Keyword(s):

Power Distribution ◽

Spectral Power ◽

Feedback System ◽

Operating Mode ◽

Spectral Responsivity ◽

Spectral Power Distribution ◽

Cryogenic Radiometer ◽

Supercontinuum Laser ◽

Radiant Power ◽

Double Monochromator

An improved monochromatic radiant source with spectral bandwidth of 4 nm based on supercontinuum laser and a double monochromator was included in absolute cryogenic radiometer-based facility to improve the accuracy of spectral responsivity measurement in the range 0.9–1.6 μm. The developed feedback system ensures stabilization of monochromatic radiant power with standard deviation up to 0.025 %. Radiant power that proceeds detector under test or absolute cryogenic radiometer varies from 0.1 to 1.5 mW in dependence of wavelength. The spectral power distribution of its monochromatic source for various operating mode is presented.

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Prediction of Atmospheric Turbulence Characteristics for Surface Boundary Layer using Empirical Spectral Methods

Revista Brasileira de Meteorologia ◽

10.1590/0102-77863540083 ◽

2020 ◽

Author(s):

Yagya Dutta Dwivedi ◽

Vasishta Bhargava Nukala ◽

Satya Prasad Maddula ◽

Kiran Nair

Keyword(s):

Boundary Layer ◽

Time Series ◽

Surface Roughness ◽

Wind Speed ◽

Atmospheric Turbulence ◽

Surface Boundary ◽

Low Frequencies ◽

Surface Boundary Layer ◽

Power Spectral ◽

Mean Wind Speed

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.

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Estimating Atmospheric Turbulence Parameters from the Envelopes of Radio Acoustic Signals

Telecommunications and Radio Engineering ◽

10.1615/telecomradeng.v55.i8.30 ◽

2001 ◽

Vol 55 (8) ◽

pp. 5

Author(s):

V. M. Kartashov ◽

V. A. Petrov ◽

Ye. G. Proshkin ◽

G. I. Sidorov

Keyword(s):

Atmospheric Turbulence ◽

Acoustic Signals ◽

Turbulence Parameters

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Numerical study of wake vortex decay and descent in homogeneous atmospheric turbulence

AIAA Journal ◽

10.2514/3.14456 ◽

2000 ◽

Vol 38 ◽

pp. 643-656 ◽

Cited By ~ 1

Author(s):

Jongil Han ◽

Yuh-Lang Lin ◽

S. P. Arya ◽

Fred H. Proctor

Keyword(s):

Atmospheric Turbulence ◽

Numerical Study ◽

Wake Vortex

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A striped pattern of snowfall and snow cover

Annals of Glaciology ◽

10.3189/s0260305500011216 ◽

1993 ◽

Vol 18 ◽

pp. 27-32

Author(s):

Yasuaki Nohguchi ◽

Takashi Ikarashi ◽

Osamu Abe ◽

Atsushi Sato

Keyword(s):

Snow Cover ◽

Atmospheric Turbulence ◽

Layered Structure ◽

Time Variation ◽

Vertical Wall ◽

Striped Pattern

A striped pattern can be seen by spraying ink on a vertical wall of a snow pit to observe the layered structure of a snow cover. This pattern is caused by variations of snowfall in time, particularly pauses in snowfall, and its structure is related to a kind of fractal. In this paper, we consider snowfall and snow cover from a viewpoint of fractals and show that the layered structure of snow cover is a record of fractals on atmospheric-turbulence phenomena through the time variation of snowfall.

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