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Method for signal level value evaluation in ESEM
Potoma, Jaroslav ; Jirák, Josef (referee) ; Čudek, Pavel (advisor)
This work deals with problematics of enviromental scanning electron microscopy and detection of signal electrons by ionization detector.The main goal of this work is to present a comparison of osciloscopical method for evaluation of signal level with method for evaluation of signal level from grayscale of common sample images. Evaluation of advantages and disadvantages of both methods.
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Determination of the chemical composition of a brass sample by X-ray fluorescence method
Tomanová, Michaela ; Čudek, Pavel (referee) ; Vaněk, Jiří (advisor)
The fluorescence spectroscopy method is used to distinguish components in gas, liquid, or solid samples. The study is based on the parameters of secondary radiation, which is emitted by each element and allows them to be identified. The distinction between each radiation is analogous to a fingerprint. Apart from quantitative and qualitative analyses, the method can be used to determine the thickness of metal layers and alloys. Laboratory analysis has a broader range of application than portable devices, which are also available. In the laboratory, two methods of measurement are available: wavelength dispersive fluorescence spectroscopy – WDXRF and energo dispersive fluorescence spectroscopy – EDXRF. A brass sample with lead additive was analyzed using EDXRF in the practical part of this diploma thesis. An X-ray apparatus from the Leybold company was employed for the analysis, which will be used for education of lower grades at the university. A measurement station and a laboratory assignment were developed as part of the thesis, the aim of which will be to determine the chemical composition of a brass sample using the X-ray fluorescence method.
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Smoothing device for FDM 3D prints
Dubský, Jan ; Čudek, Pavel (referee) ; Bayer, Robert (advisor)
This bachelor’s thesis deals with a design of a device that would smooth out 3D prints, made of various materials, using FDM 3D printers. It explains the principle of 3D printing and describes technologies used in 3D printing. In this work is an overview of materials used for 3D printing and of some selected organic solvents. It describes methods of vapour smoothing and aerosol smoothing that can be used for smoothing out of 3D prints surface. The vapour smoothing method was experimentally tested using these solvents: acetone, dichloromethane, chloroform and tetrahydrofuran. The aerosol smoothing method used a solution of acetone and dichloromethane in the ratio of 1:1. Both methods were tested on samples made of PLA, ABS, PETG and SBS. This paper describes the design of a device for smoothing of 3D prints with regard to the chemical compatibility of used construction materials and ease of use of the device.
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Design and construction of a simple music synthesizer
Ondryáš, Radek ; Čudek, Pavel (referee) ; Čech, Ondřej (advisor)
This paper deals with the topic of synthesizers. The first part of the paper provides a general description of synthesizers, their history, types, and important components. The next part of this paper focuses on sound generator chip Texas Instruments SN76477, specifically it’s functionality and ways of controlling its functions. The main part of this paper is designing and creating a synthesizer around the SN76477 sound chip and creating a box for the synthesizer from laser cut plywood.
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Semiconductors structures , charge collection method
Golda, Martin ; Čudek, Pavel (referee) ; Špinka, Jiří (advisor)
This thesis treats about semiconducting silicon structures. It describes the characteristics of the element and creation of P and N type of semiconductor and discusses about different types of faults in the crystal lattice. It deals with the description of methods for monitoring faults in semiconductor ie. determining the properties of semiconductors via EBIC, EBIV and CC methods, which are used for analysis of semiconductor devices and materials. Determining the properties of silicon components is being done by generation of charge carriers in the sample loaded in chamber of the scanning electron microscope by high energy electrons. Bellow the sample surface is being generated an electric charge which is being collected by probes. Using this data obtained by EBIC and CC were evaluated diffusion length and lifetime of electrons.
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Scintillation SE detector for VP SEM
Račanský, David ; Čudek, Pavel (referee) ; Jirák, Josef (advisor)
First part of this thesis is a theoretical essay which deals with the basics of the variable pressure scanning electron microscope, includes detection of secondary electrons with a view to a scintillation detector. The first applied part of the thesis is focused on prediction, measuring and setting-up optional working parley in vacuum electrodes scintillation detector system, with a stress small diameter hole in screenings C1 and C2. Second applied part was verify a change of working distance between sample and detector in consequence to optional solution for another work.
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Scintillation SE detector fo environmental scanning electron microscope
Odehnal, Adam ; Čudek, Pavel (referee) ; Jirák, Josef (advisor)
This work contains theory about scanning electron microscopy. It describes construction, principle of operation and sinals generated by interactions between primary electron beam and specimen. Furthermore, it describes the most common method for detection of secondary electrons using scintillation detector. Next chapters are dealing with last development stage of scanning electron microscopy, which is environmental scanning electron microscopy. Experimental part is evaluating dependency of size of detected signal with scintillation detector on pressure of water vapor in specimen chamber. It also considers appropriate size of voltages enclosed on electrodes of the scintillation detector to optimize detection.
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Electrical properties of the skin
Hellová, Miriam ; Čudek, Pavel (referee) ; Špinka, Jiří (advisor)
This work deals with the electrical properties of human skin, the possibilities of measuring its impedance, and the design of suitable electrodes for measurement. Various equivalent circuits for human skin were used, and phenomena that occur at the wet electrode-electrolyte interface, which significantly affect the measurement, were described. A description of the function of a dry planar electrode and its design for verification measurements were performed. Control measurements were performed using a EVAL-AD5933EBZ development kit in a frequency range of 5 kHz to 100 kHz at three different locations on the human body; the results were plotted in the form of the absolute value of the impedance and its phase. The accuracy of the measured values was verified by comparing the results with other works using a different electrode type. The main result of this work was to verify the possibility of using the geometry of a dry planar electrode in combination with an easily accessible evaluation board for simple diagnostic applications.
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Scintillation SE Detector for VP SEM
Kozelský, Adam ; Čudek, Pavel (referee) ; Jirák, Josef (advisor)
This work contains description of basic properties and principles of electron microscopy focused on scanning electron microscopy. It describes construction solutions of a microscope, interaction between electron beam and sample, generation of backscattered and secondary electrons. Next chapters are dealing with development of electron microscopy and environmental scanning electron microscopy. The experimental part of this thesis is focuses on the detection of secondary electrons with scintillation detector in environmental scanning electron microscope at higher pressure in the specimen chamber. Concretely is focused on optimization of collecting grid voltage and measurement of pressure dependences.
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Voltage contrast method in ESEM
Krňávek, Martin ; Čudek, Pavel (referee) ; Jirák, Josef (advisor)
This work contains theoretical description of basic features and principles of electron microscopy, with focus on environmental scanning electron microscopy. It describes function of the microscope, interactions that takes place after collision of electron pack with a sample, mainly it describes creation of back reflected electrons and secondary electrons and methods of voltage contrast. The practical part focus on voltage contrast issue by observing decomposition of electric potentials on surface of semiconductor devices and it establishes ideal working conditions for observing voltage contrast by scintillation detector of secondary electrons.
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