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Wyszukujesz frazę "optical vortex" wg kryterium: Temat

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    Wyświetlanie 1-8 z 8
    Tytuł:
    Theory of evanescent Bessel beams with a metallic sheet
    Autorzy:
    Al-Awfi, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/173463.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    optical vortex
    optical lattice
    metallic sheet
    surface modes
    Opis:
    We explain how a surface optical vortex can be created when a Bessel beam is totally reflected internally at the planar surface of a dielectric on which a metallic sheet has been deposited. A two-dimensional patterning on the surface, the strongly localized intensity distribution decays with distance vertical to the surface. The characteristics of this surface optical vortex depend on the incident beam parameters and the dielectric mismatch of the media.
    Źródło:
    Optica Applicata; 2013, 43, 3; 539-550
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Polygonal micro-whirlpools induced in ferrofluids
    Autorzy:
    Bacia, M
    Lamperska, W
    Masajada, J
    Drobczynski, S
    Marc, M
    Powiązania:
    https://bibliotekanauki.pl/articles/173951.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    ferrofluid
    hexagonal whirlpool
    optical vortex
    optical tweezers
    Opis:
    We report on the observation of the polygonal whirlpools in the thin layer of ferrofluid under illumination with a laser beam carrying optical vortex and in the presence of a vertical magnetic field. This kind of structures have attracted attention after discovering a hexagonal storm in Saturn’s atmosphere. Our polygonal whirlpools were created in a closed system (no free surfaces) in micro-scale (whirlpool diameter <20 μm) by the use of holographic optical tweezers. The polygonal shape was changed by varying the magnetic field strength or value of the optical vortex topological charge.
    Źródło:
    Optica Applicata; 2015, 45, 3; 309-316
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Focusing of linearly polarized helico-conical Lorentz beam with sine-azimuthal variation wavefront
    Autorzy:
    Bao, Y.
    Lan, J.
    Miao, Y.
    Zhang, D.
    Gao, X.
    Powiązania:
    https://bibliotekanauki.pl/articles/174305.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    Lorentz beam
    focusing properties
    optical vortex
    Opis:
    In this article a theoretical research is described into focusing of a linearly polarized helico-conical Lorentz beam with a sine-azimuthal variation wavefront. The simulation results show the vortex charge on the axis, which has an obvious modulation effect on the focal modes of the Lorenz beam under certain beam parameters and phase parameters. Both the phase parameter and the vortex charge are zero, the focal spot appears round. The focal spot is symmetric about y axis when the charge is 0 and the phase parameter is adjusted. And the focal evolution patterns vary remarkably under different beam parameters and the phase parameters. In the process of focus evolution, there appears some novel focal patterns, such as a circle, a “T”, a butterfly, a small running humanoid, a whale tail, a flower of four leaves, a serpentine, a goldfish, a Chinese knot and an octopus, which indicates that the focus mode of the optical vortex Lorentz beam can be altered by changing the phase parameters and vortex charge.
    Źródło:
    Optica Applicata; 2018, 48, 3; 373-387
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical trapping of the low index of refraction particles by focused vortex beams and two face-to-face focused beams
    Autorzy:
    Duan, Meiling
    Zhang, Hanghang
    Li, Jinhong
    Powiązania:
    https://bibliotekanauki.pl/articles/1835807.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    optical trapping
    GSM vortex beams
    two face-to-face focused beams
    radiation force
    Opis:
    Using the extended Huygens–Fresnel principle and Rayleigh scattering theory, optical trapping of the low index of refraction particles using a focused Gaussian Schell-model (GSM) non-vortex beam, a focused GSM vortex beam, and two face-to-face focused GSM vortex beams have been studied. The results demonstrate that the focused GSM non-vortex beam cannot capture the low index of refraction particles, however, the focused GSM vortex beam can be a two-dimensional trap of particles in the z-axis, and the transverse gradient force Fgrad,x and the trapping equilibrium region increase as the topological charge m increases. As the focal length f or the refractive index of particles np decreases, the radiation forces increase and the trapping ability also enhances. To trap the low index particles in three-dimensional space, we adopt that the two face-to-face focused GSM vortex beams can be used to construct an optical potential well. The transverse gradient force of two face-to-face focused GSM vortex beams is twice that of a single GSM vortex beam. The limit of the radius for the low index of refraction particles that were stably captured has also been determined. The obtained results provide valuable information for trapping and manipulating the low index of refraction particles using GSM vortex beams, which may be applied in micromanipulation, biotechnology, nanotechnology and so on.
    Źródło:
    Optica Applicata; 2020, 50, 3; 447-461
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dynamic evolution of mixed circular edge-screw dislocations
    Autorzy:
    Gao, P.
    Li, J.
    Cheng, K.
    Duan, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/173359.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    mixed circular edge-screw dislocations
    optical vortex
    circular edge dislocations
    atmospheric turbulence
    Opis:
    Based on the extended Huygens–Fresnel principle, the analytical expressions for the cross-spectral density function of mixed circular edge-screw dislocations beams propagating through atmospheric turbulence have been derived, and used to study the dynamic evolution of mixed circular edge-screw dislocations in free space and atmospheric turbulence. It is shown that the radius of circular edge dislocations increases with increasing propagation distance, and both the positions of the optical vortex and the center of circular edge dislocations are located at the point (0, 0) when mixed circular edge-screw dislocations propagate in free space. When mixed circular edge-screw dislocations propagate in the atmospheric turbulence, the position of optical vortices varies with increasing propagation distance, the circular edge dislocation evolves into a pair of optical vortices with the opposite topological charge ±1, and the pair of optical vortices will annihilate as soon as the propagation distance becomes large enough.
    Źródło:
    Optica Applicata; 2017, 47, 3; 471-481
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sieć neuronowa lokalizująca wiry optyczne rozmieszczone w regularnej strukturze
    Artificial neural network for localization of optical vortices positioned in a regular structure
    Autorzy:
    Guszkowski, T.
    Frączek, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/157563.pdf
    Data publikacji:
    2010
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    wir optyczny
    lokalizacja
    sztuczna sieć neuronowa
    optical vortex
    localization
    artificial neural network
    Opis:
    Praca prezentuje opartą na sztucznej sieci neuronowej metodę określania położenia wirów optycznych rozmieszczonych w regularnej strukturze i powstałych w wyniku interferencji trzech fal płaskich. Do uczenia i oceny jakości działania sieci neuronowej wykorzystano zestaw symulowanych obrazów, na które dodatkowo nałożono szum pomiarowy oraz zniekształcenia geometryczne wynikające z symulowanych drgań układu pomiarowego. W wyniku uczenia sieci neuronowej uzyskano neuronowy lokalizator wirów optycznych o medianie błędu lokalizacji poniżej 0,4 piksela.
    The paper presents a short introduction to the optical vortices localization problem and an Artificial Neural Network (ANN) for localization of the optical vortices positioned in a regular structure of honeycomb. The analyzed vortices form as an effect of interference of three planar waves. A set of 1800 simulated images with added noise and geometric distortions modelling experimental setup vibrations was used for ANN learning and evaluation. As a result an unidirectional ANN with 100 inputs which correspond with pixels in a 10x10 image matrix; one non-linear hidden layer of 5 neuron and 2 outputs representing the coordinates of the vortex were created. The learning criterion was Mean Square Error (MSE) and the net was taught with Levenberg-Marquardt algorithm implemented in MATLAB. Final tests were performed with 180 images excluded from ANN learning. As a result a neuronal localizator of optical vortices was obtained with the worst-case localization error less than 2.1 pixel and localization error median less than 0.4 pixel.
    Źródło:
    Pomiary Automatyka Kontrola; 2010, R. 56, nr 9, 9; 1074-1076
    0032-4140
    Pojawia się w:
    Pomiary Automatyka Kontrola
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Subpixel localization of optical vortices using artificial neural networks
    Autorzy:
    Popiołek-Masajada, Agnieszka
    Frączek, Ewa
    Burnecka, Emilia
    Powiązania:
    https://bibliotekanauki.pl/articles/1849005.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    optical vortex
    spiral phase map
    pseudo phase
    deep learning
    neural network
    Opis:
    Optical vortices are getting attention in modern optical metrology. Because of their unique features, they can be used as precise position markers. In this paper, we show that an artificial neural network can be used to improve vortex localization. A deep neural network with several hidden layers was trained to find subpixel vortex positions on the spiral phase maps. Several thousand training samples, differing by spiral density, its orientation, and vortex position, were generated numerically for teaching purposes. As a result, Best Validation Performance of the order of 10-5 pixel has been reached. To verify the usefulness of the proposed method, a related experiment in the setup of an optical vortex scanning microscope has been reported. It is shown that the vortex can be localized with subpixel accuracy also on experimental phase maps.
    Źródło:
    Metrology and Measurement Systems; 2021, 28, 3; 497-508
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Subpixel localization of optical vortices using artificial neural networks
    Autorzy:
    Popiołek-Masajada, Agnieszka
    Frączek, Ewa
    Burnecka, Emilia
    Powiązania:
    https://bibliotekanauki.pl/articles/1849096.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    optical vortex
    spiral phase map
    pseudo phase
    deep learning
    neural network
    Opis:
    Optical vortices are getting attention in modern optical metrology. Because of their unique features, they can be used as precise position markers. In this paper, we show that an artificial neural network can be used to improve vortex localization. A deep neural network with several hidden layers was trained to find subpixel vortex positions on the spiral phase maps. Several thousand training samples, differing by spiral density, its orientation, and vortex position, were generated numerically for teaching purposes. As a result, Best Validation Performance of the order of 10-5 pixel has been reached. To verify the usefulness of the proposed method, a related experiment in the setup of an optical vortex scanning microscope has been reported. It is shown that the vortex can be localized with subpixel accuracy also on experimental phase maps.
    Źródło:
    Metrology and Measurement Systems; 2021, 28, 3; 497-508
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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