نتایج جستجو برای: atmospheric turbulence
تعداد نتایج: 111918 فیلتر نتایج به سال:
Unmanned aerial vehicle experience different atmospheric uncertainties during their flight. These uncertainties caused the problem in the stability and the desired performance of the system. This research paper structured to nullify the influence of atmospheric turbulence and ground effect on the UAV. The models of Dryden turbulence is used as it is one of the major disturbances affecting the U...
We study the change in the degree of coherence of a partially coherent flat-topped (PCFT) beam propagating through atmospheric turbulence. It is shown analytically that with a fixed set of source parameters and under a particular atmospheric turbulence model, a PCFT beam propagating through atmospheric turbulence reaches its maximum value of coherence after propagating a particular distance, an...
Abstract: Sparse representation of data has grown rapidly in signal processing. The benefits of sparse regularization are economy of representation of many different varieties of data, as well as control of difficult aspects of inverse problems, e.g., regularization of ill-conditioned inverse problems. Herein we represent atmospheric turbulence point-spread-functions by training optimal overcom...
We discuss several improvements in the detection of atmospheric turbulence using SLOpe Detection And Ranging (SLODAR). Frequently, SLODAR observations have shown strong ground-layer turbulence, which is beneficial to adaptive optics. We show that current methods which neglect atmospheric propagation effects can underestimate the strength of high altitude turbulence by up to ~ 30%. We show that ...
Expressions for the average intensity of both phase-locked and non-phase-locked Airy array beams propagating through atmospheric turbulence are derived based on the extended Huygens–Fresnel principle. The evolution of the average intensity distribution of both phase-locked and non-phase-locked Airy array beams during propagation in atmospheric turbulence is examined by numerical examples and is...
Although turbulence is usually considered to be the primary cause of image blur, simultaneous and independent measurements of overall atmospheric modulation transfer function (MTF) and turbulence MTF over fairly long horizontal paths at 15-m average elevation indicate that, even at midday, aerosol MTF deriving from forward scatter is usually more dominant than turbulence MTF. Three different ex...
We propose an adaptive optics compensation scheme to simultaneously compensate multiple orbital angular momentum (OAM) beams propagating through atmospheric turbulence. A Gaussian beam on one polarization is used to probe the turbulence-induced wavefront distortions and derive the correction pattern for compensating the OAM beams on the orthogonal polarization. By using this scheme, we experime...
We present a scheme to realize obstruction- and turbulence-tolerant free-space orbital angular momentum (OAM) multiplexing link by using self-healing Bessel beams accompanied by adaptive compensation techniques. Compensation of multiple 16-ary quadrature amplitude modulation (16-QAM) data carrying Bessel beams through emulated atmospheric turbulence and obstructions is demonstrated. The obtaine...
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