scholarly journals Laser Interferometry of Turbulent Atmosphere

2012 ◽  
Vol 29 (3) ◽  
pp. 323-327
Author(s):  
Gennady Kaloshin ◽  
Igor Lukin
Keyword(s):  
Laser Beam ◽  
Atmospheric Turbulence ◽  
Turbulent Atmosphere ◽  
Random Media ◽  
Laser Interferometer ◽  
Theoretical Calculations ◽  
Laser Interferometry ◽  
High Accuracy ◽  
Angle Measurements ◽  
Beam Parameters

Abstract The paper introduces a new laser interferometry–based method for diagnosis of random media by means of high-accuracy angle measurements and describes the results of its development and testing. Theoretical calculations of the dependence of the range of the laser interferometer on laser beam parameters, device geometry, and atmospheric turbulence characteristics are reported. It is demonstrated that at moderate turbulence intensities corresponding to those observed most frequently in turbulent atmosphere at moderate latitudes and with low interference contrast values, the performance range of the laser interferometer–based device exceeds 5 km.

Vertical refraction determination using a Trimble S9 total station

2020 ◽  
Vol 954 (12) ◽  
pp. 2-9
Author(s):  
D.V. Dementiev ◽  
I.M. Zhukov ◽  
M.Y. Karavanov ◽  
I.I. Ranov ◽  
N.Yu. Litvinov
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulent Atmosphere ◽  
Measurement Accuracy ◽  
Dynamic Method ◽  
Experimental Studies ◽  
High Accuracy ◽  
Measuring Instruments ◽  
Total Station ◽  
The Real

Classical methods for determining refraction are based on Newton’s formulae for a statically stable atmosphere. However, they do not provide the required measurement accuracy due to random changes in refraction, caused by the influence of atmospheric turbulence. The aim of this work is to study the dynamic method for determining refraction in a turbulent atmosphere. The measurements were performed with a Trimble S9 total station. It was found out, that within a few seconds the angle of vertical refraction can change by dozens of arc seconds. To improve the accuracy of the results, it is necessary to determine the refraction instantly for a specific moment of observation and for a particular path, otherwise the obtained corrections will not correspond to the real angle of refraction. The introduction of a dynamic method for determining refraction requires more extensive experimental studies under various observation conditions. In the case of confirmation of the high accuracy of the dynamic method for determining the fraction, significant prospects open up for taking refraction into account and developing new more effective measuring instruments in a turbulent atmosphere.

scholarly journals Study of Wavefront Tilt Variance with Various Telescope Apertures in Indoor Convective Turbulence

2018 ◽  
Vol 68 (4) ◽  
pp. 394 ◽  
Author(s):  
Awakash Dixit ◽  
Aditya Kumar Mamgain ◽  
Vikash Porwal ◽  
Sanjay Kumar Mishra
Keyword(s):  
Fourier Transform ◽  
Laser Beam ◽  
Atmospheric Turbulence ◽  
Turbulent Atmosphere ◽  
Hurst Exponent ◽  
Experimental Setup ◽  
Aperture Size ◽  
Power Dependence ◽  
Convective Turbulence ◽  
Temporal Characteristics

Turbulent atmosphere produces random wavefront tilt in the propagating laser beam and the dynamics of turbulence is largely depend on the receiving optics aperture size. In this paper, wavefront tilt variance is studied with various telescope aperture sizes in indoor convective turbulence. A simple experimental setup is described for simulating the near ground atmospheric turbulence by generating different strengths of convective turbulence in the laboratory. A laser beam is made to propagate through the turbulence subsequently induced wavefront tilt variances are experimentally measured and analyzed statistically. The wavefront tilt variance is used to estimate the temporal characteristics using Fourier transform by varying aperture sizes and turbulence strengths (i.e. ambient, weak and moderate). The Hurst exponent, the Fried parameter and the wavefront tilt frequencies for the different turbulence strengths are calculated. The power dependence of the wavefront tilt variance on the telescope aperture size is studied and a deviation from the classical D<sup>-1/3</sup> dependence is reported.

scholarly journals Behavior of the Central Intensity of Generalized Humbert-Gaussian Beams Against the Atmospheric Turbulence

2021 ◽  
Author(s):  
Naima Nossir ◽  
Latifa Dalil-Essakali ◽  
Abdelmajid Belafhal
Keyword(s):  
Atmospheric Turbulence ◽  
Intensity Distribution ◽  
Turbulent Atmosphere ◽  
Incident Beam ◽  
Paraxial Approximation ◽  
Gaussian Beams ◽  
Central Intensity ◽  
Fresnel Integral ◽  
Special Cases ◽  
Beam Parameters

Abstract Based on the generalized Huygens-Fresnel integral in the paraxial approximation and on the Rytov theory, the analytical expression of the axial intensity distribution for the Generalized Humbert-Gaussian beams (GHGBs) propagating through a turbulent atmosphere is derived in this work. The results for the special cases of GHGBs are deduced from our study and illustrated numerically. The influence of the turbulent strength and the incident beam parameters on the propagation of these beams in the atmospheric turbulence is investigated and discussed in detail.

MANUFACTURE INVESTIGATION OF CARTRIDGE WITH BOTTOM-MOST PART FLANGE BY DIRECT EXTRUSION WITH COUNTERPUNCH. REPORT 18. EXPERIMENTAL CHECK OF THEORETICAL RESULTS FOR DIFFERENT HOLLOW RADIUSES AND BOTTOM-MOST PART THICKNESSES

2020 ◽  
Vol 0 (9) ◽  
pp. 16-23
Author(s):  
A. L. Vorontsov ◽  
◽  
I. A. Nikiforov ◽  
Keyword(s):  
Strain Hardening ◽  
Theoretical Calculations ◽  
High Accuracy ◽  
Geometric Parameters ◽  
Strength Characteristics ◽  
Experimental Check ◽  
Hardening Material ◽  
Direct Extrusion ◽  
Theoretical Results

The results of an experimental check of the obtained theoretical formulae allowing us to determine the most important parameters of extrusion cartridges with a counterpunch for different hollow radiuses and bottom-most part thicknesses are presented. Characteristics of used tools, geometric parameters of extrusion experiments, strength characteristics of deformed materials and lubricants are described in detail. Both strain-hardening material and strain-unhardening material were studied. Methodology of the theoretical calculations is demonstrated in detail. High accuracy of the obtained design formulae was confirmed.

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