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Spectral characteristics in fiber optics
Chleboun, Jiří ; Tejkal, Vladimír (referee) ; Šporik, Jan (advisor)
This bachelor’s thesis is focused on the influence of attenuation and dispersion glass and plastic optical fibers in optical transmission system. Theory of optical transmission is discussed in the theoretical part, it is defined term like spectral attenution characteristic and its division into transmission bands. Sources and detectors are itemized further, which are used for optical transmissions in fiber optics. The thesis describes the most occured effects, which influenced transmission parameters of optical fiber, like optical attenution, dispersion and aspectual polarization dispersion. Theory of plastic optical fibers is processed at the end of theoretical part of thesis. It is also processed advantages, disadvantages and useage of plastic optical fibers and they are consequently compare with glass fibers. Comparison is focused mainly on attenuation, transmission properties and useage on these types of fibers in telecommunication. Representation of spectral attenution characteristics in programme MATLAB is practical output of the bachelor´s thesis. Created programme approximates points which are got from measure optical attenuation by the Lagrange interpolation polynomial.
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Study of the properties of hyperpolarized xenon-129 for magnetic resonance imaging
Rychnovský, Jan ; Nováková,, Sabina (referee) ; Kohout,, jJaroslav (referee) ; Bartušek, Karel (advisor)
Produkce hyperpolarizovaných plynů, především helia (3He) nebo xenonu (129Xe), nachází stále rostoucí rozsah aplikací v zobrazování magnetickou rezonancí (MRI). Helium ani xenon nejsou obyčejně obsaženy v těle a experimenty tedy nejsou ovlivněny nechtěným signálem z okolních tkání. Ukázalo se, že několika hyperpolarizačními technikami může být magnetická polarizace (magnetizace) jader vzácných plynů zvýšena na hladinu, se kterou jsou praktické aplikace proveditelné. Hyperpolarizované plyny mohou tedy být užitečným nástrojem pro neinvazivní zkoumání lidského dýchání, dovolující statické zobrazování během zadržení dechu nebo zkoumání dynamiky výdechu nebo nádechu, nebo funkčního zobrazování. V neživé přírodě, mohou být hyperpolarizovaný plyny využity jako kontrastní látka při studiu mikroporézních materiálů, jako jsou zeolity, stavební látky a hmoty, atd. V této doktorské práci je popsán vývoj a konstrukce aparatury pro hyperpolarizaci xenonu (izotopu 129Xe). Nákup hyperpolarizovaného xenonu od jiných výzkumných center v zahraničí a jeho dovážení by ovšem nebylo efektivní a to zejména z důvodu náročnosti zajištění potřebných fyzikálních podmínek pro přepravu hyperpolarizovaného plynu. Toto bylo hlavní motivací k vývoji vlastní technologie pro přípravu hyperpolarizovaného xenonu. Se zvládnutou technologií by bylo možné navázat spolupráci s medicínskými zařízeními, nebo s týmy zabývající se živou nebo neživou přírodou (např. při studiu mikroporézních materiálů, gelů, v zemědělských aplikacích nebo při výzkumu využívajících zvířat, atd.). Cílem této práce je studium teorie hyperpolarizovaných vzácných plynů se zaměřením na 129Xe a experimentální ověření a změření relaxačních časů pomocí jaderné magnetické rezonance. Vzhledem k tomu, že je možné hyperpolarizované vzácné plyny skladovat pro pozdější využití, se tato práce také zabývá možnostmi zásobníku hyperpolarizovaného vzácného plynu a jeho teoretickým a experimentálním řešením. V této práci jsou popsány především dva základní typy experimentů přípravy hyperpolarizovaného xenonu. V obou jsou využity zatavené válcové skleněné vzorky naplněné xenonem a doplňujícím plynem – dusíkem, heliem. První z experimentů se zabývá měřením vlastností termálně polarizovaného xenonu a druhý měřením vlastností hyperpolarizovaného xenonu. Pro hyperpolarizaci 129Xe bylo použito výkonového laseru a experimentálně byla zkoumána jednak míra polarizace na základě změny spektrální hustoty čerpacího laserového svazku a dále pak optimální doba optického čerpání 129Xe a relaxační časy xenonu.
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Simultaneous bidirectional transfer of data and power supply over one fiber
Baura, Tomáš ; Šedivá, Soňa (referee) ; Havránek, Zdeněk (advisor)
This Bachelor’s Thesis deals with projecting and implementation of transmission systems using a single optical fibre for parallel bidirectional transmission of optical power and data signal. These systems include Polarization Division Multiplexing (PMD), Wave Division Multiplexing (WDM) and Time Division Multiplexing (TDM). The theoretical part of the thesis closely describes and specifies optical fibre, optical radiation sources and detectors as well as passive optical components suitable for transmission system implementation. Further, the thesis describes principles of individual transmission systems including a selection of particular optical and optoelectronic parts for the TDM and WDM transmission composition. Each chapter of the practical part of this document describes methods and processes used for individual measurements. First the individual parameters of individual optoelectronic and optical components of transmission systems are verified and characterized. This is followed by measuring the parameters of the composed TDM and WDM transmission systems such as optical loss, transmitted electric power efficiency, transfer speed etc. Finally, the possibility of outer optical signal detection on an integrated photodiode PIN of the laser diode is tested and verified, which could be used for both transmission and reception of data signal.
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Fiber optic source of laser radiation
Fučík, Milan ; Hudcová, Lucie (referee) ; Drexler, Petr (advisor)
This master’s thesis deals with parameters and properties of electromagnetic wave, its spread in environment and then in optical fiber, as well with optical fibers. Principle of laser sources and a issues of coupling a optical performance into optical fiber are described here. Next a function of laser diodes, power and cooling requirements are described. A block diagram of fiber optic source of laser radiation is designed as well as a circuit solution of every single block with respecting of parameters and sensitivity of used laser diode. The protection of laser diode and high-frequency modulation of optical power are solved. Subsequently the construction of every single block was done and the right function of constructional solution was tested.
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Laser diode soldering
Straka, Michal ; Holík, Milan (referee) ; Stejskal, Petr (advisor)
This work deals with the laser diode soldering. The theoretical part summarizes general and acquired findings about soldering technology and materials that occur in this process. It also describes factors that affect the reliability of solder joints. It is closely focused to the shaping of the solder joint and structure of intermetallic layer. The practical part of this work is focused on the design of equipment for laser diode soldering and subsequent shaping of the samples. The quality of soldered joint is compared against the quality of joint created using re-flow technology - remelting in in-line smelter. The structure and thickness of the intermetallic layer, the number and shape of the voids in the solder joints are compared.
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Converter card for precise control of a laser diode
Čožík, Ondřej ; Kadlec, Jaroslav (referee) ; Fiedler, Petr (advisor)
The diploma thesis deals with design of the converter card for the precise control of a laser diode. At first, there are described the principles of the laser diode, photodiode and basic functions of optical fiber sensors. Following chapter deals with description of developed converter card. In the diploma thesis are discussed all function blocks of the converter card and they are explained in detail. In the thesis are subsequently tested all problem parts of the converter card for the precise control of the laser diode, such as fast switching of the current flowing through the laser diode and design of the connection for evaluating of current pulse from the sensing photodiode. An integral part of thesis is a description of created printed circuit board and there are described all used layers and devices’ layout on the PCB. Final part of the diploma thesis deals with firmware for the microcontroller, which was made for testing of all function blocks of the converter card for the precise control of a laser diode. At the same time was developed software for PC, which communicates with the converter card via universal serial bus (USB).
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Design of measurement unit for analysis of surface materials properties
Kratochvíl, Robert ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The thesis deals with the application of laser beams for examination of material properties. The properties being examined are quality of surface finish and transmissivity of materials in the optical portion of the electromagnetic spectrum. A measuring device containing laser diodes as a source of laser beam and photodiodes for evaluation of examined phenomena serves for examination of both properties. Conversion of the signal to digital quantity and its further processing take place in a microcontroller. The data is then sent via a serial bus and a converter to a computer, where it may be saved in a user program and where the user can work with them later. The thesis contains results of reflectivity measurement of a set of metal samples with different surface finish. Transmissivity measurement was applied on a set of optical filters.
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Contactless measuring ventilator-revolution counter
Pokorný, Aleš ; Trmač, Jiří (referee) ; Michálek, Václav (advisor)
This project is about design of contactless measuring ventilator - revolution counter. The counter serves to measurement of the speed of ventilator. The measurement is based on optical method of receiving the reflected laser beam. To measure and calculate use the revolution counter the microcontroller. This measured value is diplayed on LCD. After design follows experimental measurement.
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Measurement of the optical intensity distribution at the far field
Vitásek, Jan ; Němeček, Jiří (referee) ; Wilfert, Otakar (advisor)
The topic of this master’s thesis is energy measurement of the optical intensity distribu-tion at the far field. Properties of the optical intensity and the optical power are described. In this thesis solution of wave equation is done. The plane wave, spherical wave and Gaussian beam are described. In this thesis, optical trace of laser beam from transmitter laser diode to receiver PIN photodiode is described. One of the solved problems is diffraction on the lens socket. The basic configuration for diffraction investigation on lens socket was created. There were transmitting laser diode, stop with circular apertures and PIN photodiode used in the experiment. In the other part, thesis deals with measuring and detection of the optical beam. Sorts of photodiodes and their characteristics were analysed.
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