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Diffraction on Spatial and/or Deep Objects
Hrabec, Aleš ; Petráček, Jiří (referee) ; Kotačka, Libor (advisor)
This discourse deals with a theoretical study of the radiation passage through a diffraction screen with non-zero size in the propagation direction of the radiation, i.e. the radiation passage through a three-dimensional object. Without any loss of generality, we solve the problem for cylindrical cavity in metal. The task exceeds evidently standard scalar theory of diffraction, thus we solve the problem using a waveguiding theory. Following the principles of the electromagnetic theory, we derive required formulae to determine mode distribution at the entry of the cavity. Further, we solve numerically the radiation propagation through the cavity, then we actually seek for radiation distribution at the very end of the cavity. This yields, with a help of the discrete Fourier transform, an intensity distribution of Fraunhofer diffraction pattern, consequently compared with an intesity distribution of the radiation pattern of Fraunhofer diffraction on infinitely thin circular opening having the radius of the cylinder cavity under study. A comparison of such patterns results to a conclusion, that the cavity length has a significatn influence on the diffraction pattern and more importantly, that the scalar diffraction theory appears incorrect for a coherent light passage through cavities longer than their radius squared. Similarly, the same conclusion is inversely proportional to a wavelength of the interacting radiation. Finally, we mention an existence of the so called "focal regime", when the radiation repeatedly exhibits roughly one order increased intensity on the symmetry axis of the cavity.
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Rigorous Simulation of Light Interaction with Cells
Dršata, Martin ; Kalousek, Radek (referee) ; Petráček, Jiří (advisor)
This bachelor thesis focuses on rigorous simulations of light scattering by living cells. The first part is dedicated to brief introduction to the given issues and the basic description of the often used computational methods and models of cell structures. Experimental part deals with light scattering simulations using the finite difference time domain method (FDTD). Models of spherical cell and red blood cell are used in these simulations. The aim of the calculations for the first model is to assess the accuracy of the FDTD method with respect to the analytical method using Mie theory of light scattering.
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Modelling of photonic structures using Finite-difference time-domain method
Procházka, Pavel ; Kalousek, Radek (referee) ; Petráček, Jiří (advisor)
This bachelor thesis is focused on the basic description of the finite-difference time-domain method (FDTD) which serves to the numerical solution of Maxwell's equations. FDTD is very used today because during one calculation it is possible to obtain results in wide frequency spectrum. The thesis contains deduction of \mbox{equations} for description of this method and algorithm of calculation. The main goals of this thesis are the identification of the free Meep software, which is constructed for this calculations, and understanding of its properties. Most of Meep functions are described on three examples in the second part of bachelor thesis.
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Paleomagnetický výzkum sedimentárních výplní vybraných jeskyní v České republice : závěrečná zpráva k výjimce MŽP ČR
Bosák, Pavel ; Hercman, H. ; Kadlec, Jaroslav ; Pruner, Petr ; Schnabl, Petr ; Hlaváč, Jaroslav ; Drahotová, Jana ; Pavková, Jaroslava ; Petráček, Jiří ; Rajlichová, Jana ; Drbal, K. ; Komaško, A. ; Milka, D.
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Palaeomagnetic research of fill of selected cave and karst sediments in Slovenia : progress report no. 8
Bosák, Pavel ; Pruner, Petr ; Zupan Hajna, N. ; Mihevc, A. ; Schnabl, Petr ; Šlechta, Stanislav ; Venhodová, Daniela ; Drahotová, Jana ; Man, Otakar ; Petráček, Jiří ; Komar, M. ; Horáček, I. ; Hajna, J. ; Rajlichová, Jana
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