National Repository of Grey Literature 57 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Investigating the evolution of laser induced plasmas by complementary optical and spectroscopic methods
Buday, Jakub ; Novotný, Karel (referee) ; Pouzar, Miroslav (referee) ; Kaiser, Jozef (advisor)
Laser-Induced Breakdown Spectroscopy (LIBS) is a method of analytical chemistry that provides a qualitative and quantitative sample analysis. As this method has been implemented in more and more applications, certain limitations and drawbacks have been raised from this progress. Some of these limitations are connected to the fact, that the ablation process of a~sample is fast and dynamic and the changes of the plasma plume in time and space are a question of a few microseconds. As this can cause certain limitations in the analysis process, there has been a question of how to minimize or eliminate these problems. For this purpose, supplementary methods have been more and more implemented in the LIBS experiments. The goal is simple, acquire more information from the complex process of the ablation and improve the analytical performance of LIBS, be it in the scope of qualitative or quantitative analysis. Here lies the main motivation of this dissertation thesis. Goal of this thesis was to research, implement and utilize supplementary methods, that could be used in combination with the existing LIBS experimental setup. As a result, direct plasma imaging, shadowgraphy and sound analysis systems have been implemented and streamlined into the typical analytical process. Each of these methods brings certain additional information. For direct plasma imaging, it can be the spacious-temporal morphology of the plasma plume, or the distribution of individual elements within its volume. The Shadowgraphy method can be used to calculate the energy spent on the ablation itself, pointing at the thermal properties of the analyzed sample. Lastly, the sound information from the generated shock wave is connected to the amount of ablated mass. Within this thesis, all of the mentioned supplementary methods were examined, and utilized. Insight into these methods together with the LIBS analysis was done individually for each method as well as from the point of their mutual combination. The theoretical information as well as their background is described and discussed. Moreover, the technical information is discussed and analyzed, be it the implementation of the LIBS experiment, or the actual data analysis process. This work will serve as a foundation for further research in this area, where a selection of these methods will be used in several applications that are already using LIBS but suffer from certain limitations. These methods will be used to mitigate the limitation and to elevate the potential use of the LIBS in certain areas and applications.
Diagnostics of Ti:Sa laser pulses for plasma generation
Weiss, Jiří ; Samek, Ota (referee) ; Kaiser, Jozef (advisor)
This diploma thesis is focused on investigation of temporal characteristics of laser pulses generated by oscillator with Ti:Sapphire active laser medium. In terms of properties of laserinduced plasmas the beam quality is crucial, in particular laser pulse contrast ratio. A new prototype of third order autocorrelator was designed. Pulse contrast ratio measurement is based on sum frequency generation between pulse of fundamental wavelength and its frequency doubled replica. Dynamic range of presented autocorrelator is estimated to be up to 8×10^12 which is more than currently available commercial devices can offer.
Evaluation of the Financial Situation of a Company and Proposals for Improvements
Kaiser, Jakub ; Skoupilová, Yveta (referee) ; Poláček, Tomáš (advisor)
This bachelor thesis is focused on evaluation of financial situation of the company COMET OBALY s.r.o. in the years 2015-2019 by methods of financial analysis. The work is divided into three parts. The first part is focused on theory and describes the definitions of terms and methods. The second part deals with the financial analysis of the current situation of the selected company. The last part focuses on proposals for improving the financial situation of the company.
Detection of Braking Tracks using Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Induced Fluorescence Spectroscopy (LIBS + LIFS)
Prochazka, David ; Vémola, Aleš (referee) ; Pína,, Ladislav (referee) ; Kaiser, Jozef (advisor)
The aim of this work is to investigate the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for identification of visually unrecognizable braking tracks. Identification of these tracks is based on different chemical composition of tire tread in comparison to road surface. The investigation was divided in several sequential steps – selection of suitable chemical element and its spectral line for break tracks identification; determination of the limits of detection and threshold intensity respectively for the selected chemical element; verification of LIBS ability to detect braking tracks on a real braking track. This testing braking track was prepared by exactly defined and described conditions. The detection was performed in two ways – laboratory analysis of tire treads particles collected via adhesive tape and in situ analysis via mobile apparatus. Results of both measurements showed that LIBS is able to detect visually unrecognizable braking tracks. Concepts of the devices capable of routine braking tracks identification for both possibilities were introduced.
Optimization of the experimental parameters for laser induced breakdown spectroscopy (LIBS) of selected plant samples
Prochazka, David ; Novotný, Karel (referee) ; Kaiser, Jozef (advisor)
This diploma thesis describes optimization of the experimental parameters for Laser-induced breakdown spectroscopy of plant samples. First part deals with the theoretical method of LIBS and explains the principles and terms. In the next part there is described device which was used for measurements. Main part of diploma thesis describes creation of program for measurement-automation. Main task of program was to solve the connection of autofocus on the sample with the sample automatic movement. Furthermore are described and elaborated specific measurements for optimization of the experimental parameters for Laser-induced breakdown spectroscopy of plant samples.
Development of an Algorithm for Automatic Characterization of a Sample Based on the Data Received by Means of the Laser Induced Breakdown Spectroscopy (LIBS).
Klus, Jakub ; Černohorský,, Tomáš (referee) ; Veis,, Pavel (referee) ; Kaiser, Jozef (advisor)
Submitted work concerns with the theoretical and practical requirements for an automatic characterization of samples by means of Laser-Induced Breakdown Spectroscopy (LIBS). Theoretical aspects of laser-matter interaction, plasma expansion, and plasma emission are described theoretically within this work. The description of the plasma emission is enhanced with the spectral detection systems and statistical properties of the plasma. The principle of the automatic characterization is based on the multivariate data analysis theoretical background, which presents recent trend and fundamental approach for automatic spectra analysis in LIBS. Theoretical knowledge is manifested in six applications, which are presented as a comment to published manuscripts. These publications push the frontiers of automatic spectra processing in LIBS.
Design of an optical system for expanding of the Nd:YAG laser beam in the Laser Induced Breakdown Spectroscopy (LIBS) setup
Roščák, Michal ; Antoš, Martin (referee) ; Kaiser, Jozef (advisor)
Purpose of this bachelor thesis is to design of an telescope for expanding the Nd:YAG laser gauss beam used in LIBS aparature. Intesity of the radiation around centre is approximately same and therefore is useful for focusation on sample. Designed telescope consists of two lenses. Distance between them can be adjusted by fine screw thread for attributes correction of the expanded beam. The aparature is designed with respect for system optical aberrations and final size of the telescope.
Enhancement of laser-induced plasma signal using nanoparticles
Salajková, Zita ; Galbács, Gábor (referee) ; Hidalgo, Montserrat (referee) ; Kaiser, Jozef (advisor)
Analytické metody LIBS a LA-IPC-MS založené na Laserové Ablaci (LA) nabízejí možnost rychlé chemické analýzy přímo z povrchu vzorku. Nedávno bylo ukázáno, že interakce světla s nanočásticemi může být využita pro zlepšení analytických schopností těchto metod. Při interakci nanočástic s laserovým paprskem dochází k zesílení elektromagnetického pole v jejich blízkém okolí. Pokud jsou nanočástice přítomny na povrchu vzorku analyzovaném některou z metod založenou na LA, zesílené pole vytvořené interakcí laseru s částicemi může pozměnit průběh LA, a tak ovlivnit vlastnosti laserem indukovaného plazmatu. Bylo zjištěno, že použití nanočástic může snížit práh ablace, zesílit signál a změnit vlastnosti aerosolu. Nanočásticemi zesílená LIBS (NELIBS) našla své využití tam, kde použití konvenční LIBS je problematické, a to například při analýze vzorků, kdy je jejich poškození nežádoucí nebo u analýzy roztoků mikrolitrových objemů s limity detekce nižšími než ppm. Tato dizertační práce předkládá podrobný popis jevů doprovázejících nanočásticemi zesílenou LA, založený na rozsáhlé experimentální práci a fyzikální teorii. Na základě pochopení základních principů byly vyvinuty dvě nové aplikace. Nejprve, byla NELIBS použita pro detekci kovových iontů v řetězcích amyloidů, pokročilého bio-materiálu určeného pro čištění vody. Dále byla NELIBS využita jako nová metoda pro monitorování proteinové korony vytvořené kolem nanočástic, čímž tato aplikace rozšířila klasické použití NELIBS za hranice prvkové analýzy.
Increase of robustness of communication architecture for remote spectroscopy
Cebo, Patrik ; Klus, Jakub (referee) ; Kaiser, Jozef (advisor)
This thesis deals with the design of new communication architecture of a device for remote laser spectroscopy. The conceptual model is based on the analysis of the state of the art systems for remote laser spectroscopy. Moreover, the advantages and disadvantages of custom electric buses and its failures in deployment are discussed within this thesis. The result of the work includes the design of new communication architecture supported by Ethernet standards. The next part of the thesis focuses on the customized stepper motor controller composition, which will resolve the theoretical findings arising from the analysis.
Design of a translation stage for focusing objective inside the LIBS interaction chamber
Olejník, Ivan ; Křupka, Ivan (referee) ; Kaiser, Jozef (advisor)
This diploma thesis describes the design of a translation stage for focusing objective inside the LIBS interaction chamber. It contains a description of the fundamentals and basic functions of LIBS spectroscopy. Moreover, in the thesis an overview of different translation stages as possible LIBS components is given. Their advantages and disadvantages for use in a vacuum translation stage construction are evaluated. The thesis describes the final solution of a linear translation stage for focusing objective, and his advantages for LIBS method

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3 Kaiser, Jakub
1 Kaiser, Jaroslav
1 Kaiser, Josef
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