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Measurement and analysis of the detector preamplifier
Temel, Aleš ; republic, David Novák - FEI Czech (referee) ; Klusáček, Stanislav (advisor)
This paper investigates noise characteristics of detector preamplifier in electron scanning microscopes. Various preamplifiers are measured and the lowest noise level amplifier with good level of speed is used. Further measurement of individual levels of amplifier is done and proposed the most suitable way how to achieve the total amplification. By detailed measuring of amplifier structure are found all unpleasant factors that affect the image quality. On the basis of these dates amplifier hardware is adjusted, software solutions to improve image quality designed and model control implemented, which directly controls active elements of preamplifier so that noise for given amplification was the lowest and reached required amplification.
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Analysis of the supersonic flow of gas in the differentially pumped chamber EREM
Matloch, Roman ; Vyroubal, Petr (referee) ; Maxa, Jiří (advisor)
This work describes briefly electron microscopy issue and physical model of fluid flow. Then presented diploma thesis will be describing analysis and evaluation of the impact of supersonic flow on the pressure and density in the path of the primary electron beam in the differential pumping chamber. For analysis, evaluation and examination of the issue will be used CAD and CAE (Computer Aided Engineering) programs. At the same time it will be developed a methodology of calculation applicable to supersonic flow in the low pressure system at ANSYS CFX.
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Image analysis for correction of electron microscopes
Smital, Petr ; Schwarz, Daniel (referee) ; Kolář, Radim (advisor)
This thesis describes the physical nature of corrections of an electron microscope and mathematical methods of image processing required for their complete automation. The corrections include different types of focusing, astigmatism correction, electron beam centring, and image stabilisation. The mathematical methods described in this thesis include various methods of measuring focus and astigmatism, with and without using the Fourier transform, edge detection, histogram operations, and image registration, i.e. detection of spatial transformations in images. This thesis includes detailed descriptions of the mathematical methods, their evaluation using an “offline” application, descriptions of the algorithms of their implementation into an actual electron microscope and results of their testing on the actual electron microscope, in the form of a video footage grabbed from its control computer’s screen.
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Using Computer Aided Engineering for analyse the detector
Vyroubal, Petr ; Polsterová, Helena (referee) ; Maxa, Jiří (advisor)
This master's thesis deals with influence of the shape comparison of convergent and Laval nozzles in the secondary electron detector shutters to the resulting pressure and gas flow in the secondary electron detector for environmental scaning electron mictoscope. To the detector analysis are used Computer Aided Engineering systems CAD and CAE, SolidWorks and SolidWorks Flow Simulation.
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Communication and control card for electron microscope
Robotka, Jan ; Petyovský, Petr (referee) ; Macho, Tomáš (advisor)
The main aim of this thesis is to design a communication and control card for an electron microscope, eventually for other equipments of the company Delong Instruments a.s., which is dealing with its development and production. This card should replace existing communication card because of its low computational performance. Also, it should replace control and measure card manned with A/D and D/A converters. Thus, the new card will be providing not only the communication with a superior PC and other electronic systems, but also the control of other subsystems of the electron microscope, the determining of processional states and the measuring of internal physical quantities. At the beginning the requirements were determined and the main concept was made with the inclusion of the simple block diagram. It was very important to choose a suitable microcontroller, which will be an intelligence of the whole card and so it will be the most important component. The accent was set mainly on the sufficient computational performance, high modularity of its periphery, good vision of the future innovation and support and, of course, the price. The next requirement was the implementation of the Ethernet, which will be used for the communication between the card and the superior PC. The microcontroller which was chosen have the core architecture ARM Cortex-M3 and it is described in separate chapter. The next part of this thesis is dealing with the main communication standard of the card, which is the Ethernet. After the general description, the Ethernet was mainly discussed in context of the chosen microcontroller. The possibilities of the application of higher layer TCP/IP protocols were also discussed. Implied part of the thesis was the selection of other important components, especially A/D and D/A converters. Its characteristics will have a big effect on the characteristics of the card. In the last and the most important phase the electrical scheme was designed and it was described in detail. This scheme is the main result of this thesis and it is the main document for the future realization. Designed card will be able to process and control 16 differential analogue input signals, 16 differential analogue output signals, 8 digital inputs, 8 simple digital outputs and 4 digital outputs triggered by optocouplers. It will be able to communicate with the superior PC over the Ethernet with the maximum bit rate of 100 Mbit/s, with other electronic cards over the serial line UART through the optical fibers and with other internal and external equipments over the RS-485 and RS-232.
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Contrast in image acquired by ionization detector in VP SEM
Goroš, Pavel ; Čudek, Pavel (referee) ; Jirák, Josef (advisor)
This work deal with problems of investigation materials electron beam. This project is focuses on investigation materials by the help of method environmental scan electron microscopy (ESEM) and describes her patterns. The perfection of ESEM excel above all at studies non - conducting or water containing, often biological samples. These samples not to be in no way prepared or cut – and – dries, in contradistinction to classical scanning electron microscope and thanks is under investigation their native surface structure without desiccation breaking. The general aim is determination of contrast in image acquired by ionization detector.
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Testing of service life of the bolt fastening used in electron microscopy
Habarka, Ondrej ; Radoš, Jiří (referee) ; Krejsa, Jiří (advisor)
Cílem této bakalářské práce je vybrat vhodný materiál a jeho povrchovou úpravu pro šroubový spoj s jemným závitem na držáku vzorku v elektronovém mikroskopu. První částí je přehled použitelných materiálů a povrchových úprav, které jsou nemagnetické, tudíž neovlivňují elektronový paprsek v mikroskopu. Dále se práce zabývá tvorbou testovacího zařízení na testování životnosti jednotlivých vzorků závitových tyčí. Výsledkem práce je porovnání testovaných materiálů a výběr jednoho nejvhodnějšího pro reálné použití.
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