Average intensity and spreading of a radially polarized multi-Gaussian Schell-model beam in anisotropic turbulence

2018 ◽  
Vol 218 ◽  
pp. 12-20 ◽  
Author(s):  
Mingjian Cheng ◽  
Lixin Guo ◽  
Jiangting Li ◽  
Xu Yan ◽  
Kangjun Dong ◽  
...  
Keyword(s):  
Average Intensity ◽  
Anisotropic Turbulence ◽  
Radially Polarized

scholarly journals Nonparaxial Propagation Properties of Specially Correlated Radially Polarized Beams in Free Space

2019 ◽  
Vol 9 (5) ◽  
pp. 997
Author(s):  
Lina Guo ◽  
Li Chen ◽  
Rong Lin ◽  
Minghui Zhang ◽  
Yiming Dong ◽  
...  
Keyword(s):  
Free Space ◽  
Degree Of Polarization ◽  
Average Intensity ◽  
Polarized Beams ◽  
Diffraction Integral ◽  
Spectral Density Matrix ◽  
Potential Applications ◽  
Spectral Degree ◽  
Propagation Properties ◽  
Radially Polarized

A specially correlated radially polarized (SCRP) beam with unusual physical properties on propagation in the paraxial regime was introduced and generated recently. In this paper, we extend the paraxial propagation of an SCRP beam to the nonparaxial regime. The closed-form 3 × 3 cross-spectral density matrix of a nonparaxial SCRP beam propagating in free space is derived with the aid of the generalized Rayleigh–Sommerfeld diffraction integral. The statistical properties, such as average intensity, degree of polarization, and spectral degree of coherence, are studied comparatively for the nonparaxial SCRP beam and the partially coherent radially polarized (PCRP) beam with a conventional Gaussian–Schell-model correlation function. It is found that the nonparaxial properties of an SCRP beam are strikingly different from those of a PCRP beam. These nonparaxial properties are closely related to the correlation functions and the beam waist width. Our results may find potential applications in beam shaping and optical trapping in nonparaxial systems.

scholarly journals Effects of Anisotropic Turbulence on Propagation Characteristics of Partially Coherent Beams with Spatially Varying Coherence

2018 ◽  
Vol 8 (11) ◽  
pp. 2025 ◽  
Author(s):  
Wentao Dao ◽  
Chunhao Liang ◽  
Fei Wang ◽  
Yangjian Cai ◽  
Bernhard J. Hoenders
Keyword(s):  
Turbulent Medium ◽  
Average Intensity ◽  
Weak Turbulence ◽  
Anisotropic Turbulence ◽  
Turbulence Regime ◽  
Coherence Parameter ◽  
Coherent Beams ◽  
Local Intensity ◽  
Spatially Varying ◽  
Analytical Expressions

Based on the extended Huygens-Fresnel (eHF) principle, approximate analytical expressions for the spectral density of nonuniformly correlated (NUC) beams are derived with the help of discrete model decompositions. The beams are propagating along horizontal paths through an anisotropic turbulent medium. Based on the derived formula, the influence of the anisotropic turbulence (anisotropy factors, structure parameters) on the evolution of the average intensity, the shift of the intensity maxima and the power-in-the-bucket (PIB) are investigated in detail through numerical examples. It is found that the lateral shifting of the intensity maxima is closely related to the anisotropy factors and the strength of turbulence. Our results also reveal that, in the case of weak turbulence, the beam profile can retain the feature of local intensity sharpness, but this feature degenerates quickly if the strength of the turbulence increases. The value of PIB of the NUC beams can be even higher than that of Gaussian beams by appropriately controlling the coherence parameter in the weak turbulence regime. This feature makes the NUC beams useful for free-space communication.

scholarly journals Second-order statistics of a radially polarized cosine-Gaussian correlated Schell-model beam in anisotropic turbulence

2016 ◽  
Vol 24 (11) ◽  
pp. 11626 ◽  
Author(s):  
Jing Wang ◽  
Shijun Zhu ◽  
Haiyan Wang ◽  
Yangjian Cai ◽  
Zhenhua Li
Keyword(s):  
Order Statistics ◽  
Second Order ◽  
Second Order Statistics ◽  
Anisotropic Turbulence ◽  
Radially Polarized

Propagation of a radially polarized partially coherent rotating elliptical cosine-Gaussian beam with vortices in anisotropic turbulence

2019 ◽  
Vol 125 (5) ◽  
Author(s):  
Liping Zhang ◽  
Dongmei Deng ◽  
Xingyu Chen ◽  
Fang Zhao ◽  
Jingli Zhuang ◽  
...  
Keyword(s):  
Gaussian Beam ◽  
Anisotropic Turbulence ◽  
Partially Coherent ◽  
Radially Polarized

HYDROLOGICAL REGIME AND FREEZING OF HUMMOCKY BOGS ON THE EUROPEAN NORTH OF RUSSIA

2019 ◽  
Vol 12 (9-10) ◽  
pp. 38-48
Author(s):  
V. I. Batuev ◽  
I. L. Kalyuzhny
Keyword(s):  
Water Level ◽  
Hydrological Regime ◽  
Average Intensity ◽  
Water Level Rise ◽  
Northern European ◽  
European North ◽  
Bog Waters ◽  
Northern European Russia ◽  
Seasonal Thawing ◽  
First Time

The development of the European North of Russia, where flat and high-hummocky bog complexes are spread, requires information on the processes of formation of their hydrological regime and freezing of this territory. For the first time, based on observational data, for the period from 1993 to 2013, characteristics of the hydrological regime and freezing of hummocky bogs in Northern European Russia are presented, the case study of the Lovozerskoye bog. The observations were carried out in accordance with the unified methods, approved for the specialized network of Roshydromet bog stations. The regularities of the formation of the hydrological regime of hummocky bogs have been revealed: bog water level drops dramatically from the beginning of freezing to the end of March, rises during snow melt period, slightly drops in summer and rises in autumn. The main feature of hummocky bogs is permafrost, which determines their specific structure. It has been discovered that gravitation snowmelt and liquid precipitation waters relatively quickly run down the hummocks over the frozen layer into hollows between them. Levels of bog waters on the hummocks are absent for a longer period of time. In spring, the amplitude of water level rise in swamplands is on average 60–80 cm. Air temperature and insulation properties of snow are the main factors that influence the bog freezing. Hummocks freeze out as deep as 63–65 cm, which corresponds to the depth of their seasonal thawing in the warm period of the year, and adjoin the permafrost. The greatest depth of freezing of the swamplands is 82 – 87 cm, with an average of 68 cm. The frozen layer at swamplands thaws out from both its upper and bottom sides. The melting of the frozen layer at hummocks occurs only from the bog surface with an average intensity of 0,51 cm/day.

Paraxial Propagation Properties of Radially Polarized Odd‐Pearcey Gaussian Beams in Free Space

2021 ◽  
pp. 2100055
Author(s):  
Mingyue Fang ◽  
Xiang Liao ◽  
Jiajia Zhao ◽  
Chuangjie Xu ◽  
Yixiao Zhang ◽  
...  
Keyword(s):  
Free Space ◽  
Gaussian Beams ◽  
Propagation Properties ◽  
Radially Polarized

scholarly journals A contour property based approach to segment nuclei in cervical cytology images

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Iram Tazim Hoque ◽  
Nabil Ibtehaz ◽  
Saumitra Chakravarty ◽  
M. Saifur Rahman ◽  
M. Sohel Rahman
Keyword(s):  
Pap Smear ◽  
State Of The Art ◽  
Cervical Cytology ◽  
Average Intensity ◽  
Nucleus Size ◽  
Real Dataset ◽  
Art Methods ◽  
Convolution Filter ◽  
Cervical Cells ◽  
Nucleus Segmentation

Abstract Background Segmentation of nuclei in cervical cytology pap smear images is a crucial stage in automated cervical cancer screening. The task itself is challenging due to the presence of cervical cells with spurious edges, overlapping cells, neutrophils, and artifacts. Methods After the initial preprocessing steps of adaptive thresholding, in our approach, the image passes through a convolution filter to filter out some noise. Then, contours from the resultant image are filtered by their distinctive contour properties followed by a nucleus size recovery procedure based on contour average intensity value. Results We evaluate our method on a public (benchmark) dataset collected from ISBI and also a private real dataset. The results show that our algorithm outperforms other state-of-the-art methods in nucleus segmentation on the ISBI dataset with a precision of 0.978 and recall of 0.933. A promising precision of 0.770 and a formidable recall of 0.886 on the private real dataset indicate that our algorithm can effectively detect and segment nuclei on real cervical cytology images. Tuning various parameters, the precision could be increased to as high as 0.949 with an acceptable decrease of recall to 0.759. Our method also managed an Aggregated Jaccard Index of 0.681 outperforming other state-of-the-art methods on the real dataset. Conclusion We have proposed a contour property-based approach for segmentation of nuclei. Our algorithm has several tunable parameters and is flexible enough to adapt to real practical scenarios and requirements.

Decay of anisotropic turbulence.

AIAA Journal ◽  
1973 ◽  
Vol 11 (4) ◽  
pp. 546-548 ◽  
Author(s):  
HENRY J. TUCKER ◽  
S. FlRASAT ALI
Keyword(s):  
Anisotropic Turbulence
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