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Transmission of the beam in the turbulent atmosphere

Author: LiChengLiang
Tutor: PuJiXiong
School: Huaqiao University
Course: Physical Electronics
Keywords: Atmospheric turbulence Flicker Ghost imaging Vortex beams High - Sibei Sale beam
CLC: O436
Type: Master's thesis
Year: 2011
Downloads: 125
Quote: 0
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The laser has a wide range of applications in optical communications, remote sensing, monitoring, and thus the transmission characteristics of the laser beam in atmospheric turbulence has a very important significance. Due to the impact of turbulence, the beam will occur in the atmosphere transmission light intensity fluctuations, pixel jitter, beam diffusion of atmospheric turbulence effects. It is these turbulence effect, the quality of the transmitted beam in the atmosphere will be greatly reduced. How to reduce the impact of the turbulent atmosphere of the beam has become an important research topic. Seeking a special beam to reduce turbulence effect has been the direction of the majority of scholars, many different laser beam in turbulence in the transmission characteristics of the study have been reported in the newspapers. This article a brief description of the basic theory of atmospheric turbulence, the relevant parameters of the turbulent atmosphere and several major atmospheric refractive index of the power spectrum model of intensity fluctuation effect of turbulence scintillation index calculation was introduced, in order to the research beam in the turbulent atmosphere of transmission theoretical preparation. Atmospheric environment, combined with ghost imaging in the practical application of a theoretical study of the turbulent atmosphere partially coherent light ghost imaging, according to the classical optical coherence theory and the generalized Huygens - Fresnel integral, been a part of the atmospheric turbulence environment Coherent ghost imaging analytic formulas, the ghost image quality of the light source coherence length, the transmission distance, turbulence intensity. The study showed that: the larger the light source spot, ghost image quality is better; increase in the distance between the turbulence intensity light source coherence length and the light source and the object to be imaged, and will reduce the ghost image quality. A light beam having a spiral phase factor is referred to as the vortex beam, vortex beam of photons carry orbital angular momentum the orbital angular momentum of the photons can be utilized to encode information, and applied to the free-space optical communications, and thus research vortex beam The transmission characteristics of the atmospheric turbulence is of great significance. In this paper, the scintillation index measuring instrument measuring the vortex beam scintillation index, and compare the Gaussian beams and topological charge vortex beam scintillation index change, the analysis of the topological charge of the scintillation index. The experiments show that: in the same turbulent environment, the vortex beam scintillation index is smaller than the Gaussian beam scintillation index, and the greater the number of topological charge smaller the beam scintillation index. High-end high Spey Sale beam diffraction characteristics and carry orbital angular momentum of its generation and transmission also aroused great interest of scholars, take advantage of the spatial light modulator and axicon produces high-end high-the Spey Sale beam at the same time, the paper The high-end high-the Spey Sale beam transmission in simulated atmospheric turbulence. The study showed that: due to the impact of atmospheric turbulence, diffraction area, high-the Spey Sale beam beam expander phenomenon also occurs even in the absence and the presence of the orbital angular momentum will reduce the impact of the turbulence on the beam.

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CLC: > Mathematical sciences and chemical > Physics > Optics > Physical optics ( wave optics )
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