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Special diffractive element based on fractals
Kala, Miroslav ; Bednář, Josef (referee) ; Kotačka, Libor (advisor)
This diploma project is focused on use the fractals in diffractive optical elements. Properties of diffraction patterns of various fractals are investigated. Properties of some simpler non-fractal structures are investigated too. Diffraction patterns are created by computer with program written in Delphi programming language. Potentialities of use the fractals in security optical elements (holograms) and their advantages against the classic non-fractal structures.
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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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Measurement of the Mechanical Stability of Buildings and Consoles Used for the FSO Links
Kočvara, Pavel ; Němeček, Jiří (referee) ; Wilfert, Otakar (advisor)
The Master's thesis deals with the determination of measurement method of deflection the axis of the optical beam from its ideal position, which is caused by action of force of strong winds affecting the positional stability of the building or supporting structure (tower) used for placement of FSO links'heads. The thesis informs the readers about the other causes of deflection of beam axis in a real environment, about methods of determining the position of the beam axis in the plane perpendicular to the beam axis and the basic properties and parameters of the Gauss beams, including the phenomenon of diffraction on the output aperture of the laser transmitter.
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Laser transmitter with fiber
Hašek, Jaroslav ; Němeček, Jiří (referee) ; Wilfert, Otakar (advisor)
This master´s thesis deals with communication which is provided by optical devices. Optical wireless links are enforced due to high bit rate, responsibility and noise immunity. Main part of this master´s project is devoted to optical fibre, its characteristic and its usage in laser transmitter.
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D8 - ADVANCE X-RAY Difractometer Adjustment
Černý, Lukáš ; Šrámek, Miroslav (referee) ; Žák, Roman (advisor)
This graduation thesis deals with Bruker AXS D8 Advance adjustment. Target of this thesis is design and realization of equipment which is going to be applicable on existing D8 advance machine and works with Göbel mirror adjustment. Mentioned adjustment is basic part of service operations necessary for D8. Introduction deals with theory of diffraction and basics of X-ray. Following part is presenting design of model which can be applicable and useful for solving of our problem. This design is completed with function device. This device realization is created by driving mechanism, control unit and mechanical adapter which is flexible and compatible with existing D8 Advance machine. All parts of designed device are fully described and complemented for full technical documentation, which is part of attachments.
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Particle size of solid ash
Lochman, Petr ; Špiláček, Michal (referee) ; Hrnčířová, Michaela (advisor)
This bachelor thesis deals with possible ways of analyzing the size of solid particles of ash and their effect on the environment. The first half is devoted to combustion, ash formation and fuels, which are commonly used for energy production. The second half is devoted to a practical analysis of solid particles of different ash samples and their subsequent evaluation.
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Fresnel Incoherent Correlation Holography (FINCH)
Bouchal, Petr ; Slabý, Tomáš (referee) ; Chmelík, Radim (advisor)
In the Bachelor's thesis, the recently proposed method known as Fresnel Incoherent Correlation Holography (FINCH) is examined both theoretically and experimentally. Its main advantage consists in a possibility to realize holographic reconstruction of 3D objects illuminated by incoherent light. In FINCH, the object recording is performed applying methods of optical holography and digital diffractive optics. The object reconstruction is realized numerically and utilizes principles of digital holography. In experiments, the modern optoelectronic devices known as Spatial Light Modulators are effectively used. The Bachelor's thesis includes a short review including description of the basic principles of FINCH but its own contribution consists in the mathematical description of the method and creation of the numerical simulation model in Matlab. The main result of the thesis is design and realization of experiments enabling verification of the method. In the Bachelor's thesis, results of two independent experiments realized with different types of Spatial Light Modulators HOLOEYE and HAMAMATSU are presented. An agreement of experimental results with theoretical predictions is very good. A short discussion of the obtained results, further research topics and FINCH applications is also included in the Bachelors's Thesis.
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Synthetic Holography
Tvarog, Drahoslav ; Chmelík, Radim (referee) ; Kotačka, Libor (advisor)
The thesis presents method of a creation of computer-generated holograms. The first part is devoted to an introduction of theoretical principles of a generation of synthetic holograms. The second part of the discourse deals with several practical methods of synthetic holograms creation. We present a computer code computing a discrete Fourier transform of an input image. The output of the code is an image matrix binarized in a specifically given way and printed on a transparent slide. When reconstructing the synthetic hologram we initially illuminate the slide with CGH by a plane wave and a reconstructed pattern is magnified through a camera objective to obtain a pattern observable by naked eyes. Finally, we analyze the quality of reconstructed pictures obtained from the synthetic holograms.
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