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Tolerances and Misalignment Aberrations for Electron Optical Elements and Systems
Sháněl, Ondřej ; Radlička, Tomáš (oponent) ; Tiemeijer,, Peter Christiaan (oponent) ; Zlámal, Jakub (vedoucí práce)
Inaccuracies in the production and assembling of rotationally symmetric lenses and deflectors and their accurate positioning in the electron optical system can be treated as an additional field with specific type of symmetry. The additional fields can be evaluated with the help of the finite element method in the program EOD. Tolerance analysis allows evaluation of the requirements on the dimensions and position of individual elements and their parts. Elimination of misalignment aberrations consists in determining the type and position of correcting deflection coils and multipoles so that these additional aberrations are removed or their effect is minimized. The aim of the dissertation is the analysis of the effect of misalignment aberrations and behavior of misaligned systems of transmission electron microscopes.
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Phase plates for transmission electron microscopy
Špičáková, Tereza ; Sháněl, Ondřej (oponent) ; Konečná, Andrea (vedoucí práce)
Samples consisting of light atoms, such as biological samples, provide low contrast in the transmission electron microscope images. However, introducing an additional phase shift between the electrons carrying the information of the sample and the background electrons can enhance the contrast significantly without impacting the quality of the image. This effect can be achieved by using a phase plate in the microscope. Phase plates based on a thin amorphous carbon film are used in conventional transmission electron microscopes. In recent years, extensive research in advanced phase plate design has been carried out. Yet, only a few studies on materials for the thin film-based phase plates have been published. For this reason, the main goal of this master’s project is to design measurements of the phase-shifting properties of various materials. In the first part of this thesis, the theory of electron wave imaging in a transmission electron microscope is described. Then, we review and compare phase plate designs. In the second part, four designs of the experimental setup are presented, out of which two have been tested experimentally. The measurements have been performed on a series of samples of different thicknesses and materials, and the results have been appropriately analysed. Furthermore, the qualitative behaviour of the tested designs has been compared to theoretical computations.
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Influence of saddle deflection coils inaccuracy on image aberrations
Mičulka, Martin ; Oral, Martin (oponent) ; Sháněl, Ondřej (vedoucí práce)
This thesis deals with computing of parasitic magnetic fields of the misaligned deflection coil due to the manufacturing imperfections. The relation between the multipole magnetic fields and the asymmetric winding distribution of an electron deflection system is discussed. Novel and fast 2D methods of calculation are introduced. The results are then compared with the 3D final elements method as well as with an experiment. Consequently, the influence of the parasitic multipole fields due to the manufacturing imperfections on astigmatism is examined.
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Návrh fokusačního a vychylovacího systému elektronové svářečky
Franc, Viktor ; Sháněl, Ondřej (oponent) ; Zlámal, Jakub (vedoucí práce)
Hlavními částmi elektronové svářečky jsou zdroj elektronů, akcelerátor, magnetická čočka s vychylovacím systémem a stigmátorem, svařovací komora s manipulátorem vzorku a vakuový systém. Tato diplomová práce započíná návrh prototypu elektronové svářečky. Přesněji je věnována jak elektronově optickému, tak konstrukčnímu návrhu magnetické čočky, vychylovacího systému, korekčního systému, svařovací komory a vakuového systému.
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Design of the Transmission Electron Microscope projection system for the Single Particle Analysis
Bačo, Ondřej ; Tiemeijer, Peter (oponent) ; Sháněl, Ondřej (vedoucí práce)
This thesis deals with the design of the transmission electron microscope (TEM) projection system for single particle analysis (SPA). The projection system design was created in Electron Optical Design (EOD) software version 4.020. The lens excitation series for projection system magnifications ranging from 50 to 10000 were calculated using thin lens approximation approach, thick lens approximation approach, EOD linear focus method and EOD nonlinear focus method, as implemented in 5.003 version. Obtained results were compared and validated utilizing EOD real particle tracing method.
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Parasitic Aberrations of Electrostatic Deflectors
Badin, Viktor ; Radlička, Tomáš (oponent) ; Sháněl, Ondřej (oponent) ; Lencová, Bohumila (vedoucí práce)
The present doctoral dissertation deals with parasitic aberrations in electrostatic multipole optical components arising due to mechanical misalignment of the electrodes. Manufacturing and alignment precision of the mechanical parts can have a significant influence on the performance of electron beam machines such as microscopes and lithography (EBL) systems. Defects, imprecisions, and all other symmetry violations generate so-called parasitic fields whose effects on the particle beam are referred to as parasitic aberrations. Perturbations of axially symmetric lenses are usually treated using Sturrock's principle. Displacement or tilt of an entire multipole component can be analyzed in a globally shifted or tilted coordinate system. The present thesis deals with the misalignment of individual electrodes, which cannot be easily described with the mentioned approaches and usually need to be solved in 3D. Calculations in 3D are generally slower and have higher computational requirements than 2D tools standardly used in charged particle optics programs. To calculate parasitic fields generated by electrode misalignment, a 2D perturbation method compatible with the finite element method (FEM) has been developed in this thesis based on shifting the coordinate system locally around the affected electrode. Electrodes misaligned in each axis of the cylindrical coordinate system (longitudinal, radial, and azimuthal) are studied. Possible applications of the derived general method are shown, such as ellipticity and transverse shift of the entire deflector. For each of these cases, the resulting parasitic axial field functions (AFF) calculated in 2D are validated against the 3D solution. In addition to comparing parasitic AFFs, a case study is provided where the effect of parasitic aberrations on the electron beam in an entire optical column of an EBL system is shown, again validated against the 3D solution. The proposed method of calculating parasitic fields in 2D allows understanding the effects of different manufacturing and assembling tolerances, characterizing these effects, designing aberration correction devices, and optimizing mechanical tolerance requirements. The developed method can be run on any standard PC and is 1--2 orders of magnitude faster than solving the perturbed system in 3D.
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Non-linear imaging in 100 keV transmission electron microscopy
Brzica, Michal ; Zlámal, Jakub (oponent) ; Sháněl, Ondřej (vedoucí práce)
The bachelor thesis deals with the description of imaging in a transmission electron microscope. The thesis is mainly focused on the derivation of the equation describing the observed intensity in the detector plane. A comparison of the form of the linear and non-linear equations for the observed intensity is followed by a comparison of the derived theory with photographed samples at different accelerating voltages. The effect of the individual non-linear terms on the observed resolution is then determined.
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Návrh fokusačního a vychylovacího systému elektronové svářečky
Franc, Viktor ; Sháněl, Ondřej (oponent) ; Zlámal, Jakub (vedoucí práce)
Hlavními částmi elektronové svářečky jsou zdroj elektronů, akcelerátor, magnetická čočka s vychylovacím systémem a stigmátorem, svařovací komora s manipulátorem vzorku a vakuový systém. Tato diplomová práce započíná návrh prototypu elektronové svářečky. Přesněji je věnována jak elektronově optickému, tak konstrukčnímu návrhu magnetické čočky, vychylovacího systému, korekčního systému, svařovací komory a vakuového systému.
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