Estimate of effect of initial field distribution using streamlines of the average Poynting vector on the change of the effective spot size of the laser beam propagating in the turbulent atmosphere

2015 ◽  
Author(s):  
D. A. Marakasov ◽  
D. S. Rytchkov
Keyword(s):  
Laser Beam ◽  
Field Distribution ◽  
Turbulent Atmosphere ◽  
Poynting Vector ◽  
Spot Size ◽  
Initial Field

Expansion of a Focused Laser Beam in the Turbulent Atmosphere

1971 ◽  
Vol 49 (10) ◽  
pp. 1233-1248 ◽  
Author(s):  
A. D. Varvatsis ◽  
M. I. Sancer
Keyword(s):  
Laser Beam ◽  
Free Space ◽  
Turbulent Atmosphere ◽  
Focal Plane ◽  
Spot Size ◽  
Small Aperture ◽  
Forward Scatter ◽  
Green’S Theorem ◽  
Focused Beams ◽  
Weakly Dependent

This work examines the expansion of a focused laser beam in the turbulent atmosphere. The formulation is based on Green's theorem and the valid assumption that the turbulent atmosphere is a forward-scatter medium for wavelengths of interest (0.6 μ < λ < 11 μ). The main results are: (1) the spot size at the free-space focal plane in the presence of turbulence is independent of the aperture radius, and is only weakly dependent on the wavelength, (2) the focal plane can be significantly shifted for small aperture radii, short wavelengths, and long free-space focal lengths, (3) the effect of the atmosphere is pronounced only close to the free-space focus and very far away, and (4) the turbulent atmosphere has a stronger effect on weakly focused beams rather than strongly focused beams, except very close to the free-space focus, where the effect is more pronounced for strongly focused beams.

scholarly journals Self-Focusing of Hermite-Cosh-Gaussian Laser Beams in Plasma under Density Transition

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Manzoor Ahmad Wani ◽  
Niti Kant
Keyword(s):  
Laser Beam ◽  
Plasma Density ◽  
Focal Spot ◽  
Beam Width ◽  
Spot Size ◽  
Laser Beams ◽  
Equation Approach ◽  
Focal Spot Size ◽  
Self Focusing ◽  
Small Spot

Self-focusing of Hermite-Cosh-Gaussian (HChG) laser beam in plasma under density transition has been discussed here. The field distribution in the medium is expressed in terms of beam-width parameters and decentered parameter. The differential equations for the beam-width parameters are established by a parabolic wave equation approach under paraxial approximation. To overcome the defocusing, localized upward plasma density ramp is considered, so that the laser beam is focused on a small spot size. Plasma density ramp plays an important role in reducing the defocusing effect and maintaining the focal spot size up to several Rayleigh lengths. To discuss the nature of self-focusing, the behaviour of beam-width parameters with dimensionless distance of propagation for various values of decentered parameters is examined by numerical estimates. The results are presented graphically and the effect of plasma density ramp and decentered parameter on self-focusing of the beams has been discussed.

scholarly journals Studies on propagation of laser beam array with initial phase distributions in a turbulent atmosphere

2009 ◽  
Vol 58 (7) ◽  
pp. 5098
Author(s):  
Zheng Wei-Wei ◽  
Wang Li-Qin ◽  
Xu Jing-Ping ◽  
Wang Li-Gang
Keyword(s):  
Laser Beam ◽  
Turbulent Atmosphere ◽  
Initial Phase ◽  
Beam Array

scholarly journals EFFECT OF THE RUBY LASER MICROBEAM ON MITOCHONDRIA OF KB CELLS SUPRAVITALLY STAINED BY PINACYANOL

1969 ◽  
Vol 41 (2) ◽  
pp. 424-430 ◽  
Author(s):  
Yasukazu Tanaka
Keyword(s):  
Laser Beam ◽  
Ruby Laser ◽  
Focal Length ◽  
Direct Interaction ◽  
Experimental System ◽  
Spot Size ◽  
Kb Cells ◽  
Focal Spot Size ◽  
Laser Microbeam ◽  
Opaque Material

With pinacyanol as the supravital stain, a preferential effect on mitochondria of KB cells was achieved by the irradiation with the ruby laser beam. The observation confirmed the results of other workers using janus green B in the same experimental system. The preferential effect on mitochondria was noted in the area extending 8–10 µ beyond the nonpreferential damage of 4–5 µ in diameter. The opaque material associated with mitochondria possibly represented coagulated protein. The effect involved cristae mitochondriales without severe disarrangement of their structure. The opaque material could be interpreted as the result of direct interaction between mitochondria and the laser beam, even though the mitochondria were noted outside of the previously estimated focal spot size of about 3 µ Within the thickness of 2–4 µ of monolayered cells, larger areas of damage can be accounted for by divergence of the beam which is focused by a microscope objective of very short focal length. A threshold of biologic effectiveness is probably also involved.

Formation of given field distribution in laser-beam cross section

1984 ◽  
Vol 27 (5) ◽  
pp. 411-413
Author(s):  
V. B. Korshikov ◽  
P. R. Lakhno ◽  
V. N. Rozhdestvin
Keyword(s):  
Laser Beam ◽  
Cross Section ◽  
Field Distribution ◽  
Beam Cross Section

Laser Beam Shaping and Spot Size

1997 ◽  
Vol 1 (1) ◽  
pp. 1.6.1-1.6.5
Author(s):  
Howard M. Shapiro
Keyword(s):  
Laser Beam ◽  
Spot Size ◽  
Beam Shaping ◽  
Laser Beam Shaping
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