This thesis is focused on the environmental scanning electron microscopes including a description of the basic physical mechanisms. It describes the design and realization of the electrode ionization detector system suitable for the detection of signal electrons with a greater proportion of secondary electrons. It also deals with simulations of trajectories of electrons in the electrostatic field of the detector, and with verification of the functionality of the detector in the environment of water vapors in the specimen chamber of the electron microscope.

Electron microscopy has become an essential component in many scientific fields, in which it contributes to new discoveries. The microscopy itself is continually being developed and the limits, which seemed to be insurmountable, have been overcome. The instruments have become user friendlier and their mobility enables flexible practical use in the field. The subject of this work is the design of a scanning electron microscope, the calculation of a magnetic curcuit of an immersion objective combined with standard lens, the theoretical calculation of a microscope resolution and the design solution of the mechanical parts of the microscope with a sample manipulator. The thesis includes a description of the electron microscopy development summarizing it briefly from the very beginning up to now. It also deals with electron sources, especially the Shottky cathode, which is to be the main object observed by the proposed device. The work also contains a description of the calculation of the microscope resolution as a function of the current density distribution. Another interesting issue included in the theoretical part is the signal detection, a description of several types of detectors and possible signal processing. The solution of the thesis includes a description of the concept of the scanning electron microscope with an explanation of the distribution of combined lens functions. The optical diagram shows the arrangement of the electron optics system and the distibution of pressure in the chamber of the microscope. The theoretical calculation is devoted to the magnetic curcuit design of the objective and to the resolution of the microscope for a given extent of working distances. Two modifications of the lens were designed – a standard simple objective and a combination of the standard objective with the immersion magnetic one. The results of both modifications are given for the parameters to be compared. The combined objective was designed with the possibility of use in two modes, as a standard and immersion lens. The deflection system is also divided into two modes, as a single deflection for the standard lens and as a two-dimension deflection for the immersion lens. Detectors for secondary electrons (SE) and detectors for back scattered electrons (BSE) will be used for the signal detection. The design of the microscope is another large part, which gives details on the most significant components of the microscope. The content of the technical solution is a three-dimensional computer model, created in Autodesk Inventor, which also includes a sample manipulator driven by piezoelectric actuators.

Crystalline films of vanadium dioxide were obtained through thermal annealing of amorphous vanadium dioxide thin films sputtered on silicon dioxide. An annealing process was found that yielded polycrystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated single-crystal particles. Orientation Imaging Microscopy (OIM) was used to characterize and study the phase and the orientation of the vanadium dioxide crystals obtained, as well as to diferentiate them from other vanadium oxide stoichiometries that may have formed during the annealing process. There was no evidence of any other vanadium oxides present in the prepared samples. Indexing of the crystals for the orientation study was performed with the Kikuchi patterns for the tetragonal phase of vanadium dioxide, since it was observed that the Kikuchi patterns for the monoclinic and tetragonal phases of vanadium dioxide are indistinguishable by OIM. It was found that a particle size of 100 nm was in the lower limit of particles that could be reliably characterized with this technique. It was also found that all VO2 crystals large enough to be indexed by OIM had a preferred orientation with the C axis of the tetragonal phase parallel to the plane of the specimen.

Near field imaging using microwaves in medical applications is of great current interest for its capability and accuracy in identifying features of interest, in comparison with other known screening tools. Many imaging methods have been developed over the past two decades showing the potential of microwave imaging in medical applications such as early breast cancer detection, analysis of cardiac tissues, soft tissues and bones. Microwave imaging uses non-ionizing ultra wideband (UWB) electromagnetic signals and utilises tissue-dependent dielectric contrast to reconstruct signals and images using radar-based or tomographic imaging techniques. Microwave imaging offers low health risk, low operational cost, ease of use and user-friendliness. This study documents microwave imaging experiments for early breast cancer detection and bone fracture detection using radar approach. An actively tuned UWB patch antenna and a UWB Vivaldi antenna are designed and utilised as sensing elements in the aforementioned applications. Both UWB antennas were developed over a range of frequency spectrum, and then characteristics were tested against their ability for microwave imaging applications by reconstructing the 3D Inversion Algorithm. An experiment was conducted using patch antenna to test the detection of variable sizes of cancer tissues based on a simple phantom consisting of a plastic container with a low dielectric material emulating fatty tissue and high dielectric constant object emulating a tumour, is scanned between 4 to 8 GHz with the patch antenna. A 2-D image of the tumour is constructed using the reflected signal response to visualize the location and size of the tumour. A Vivaldi antenna is designed covering 3.1 to 10.6 GHz. The antenna is tested via simulation for detecting bone fractures of various sizes and 2-D images are generated using reflected pulses to show the size of fracture. The Vivaldi antenna is optimised for early breast cancer detection and detailed simulated study is carried out using different breast phantoms and tumour sizes. Simulations are backed with the experimental investigation with the test setup used for patch antenna. Generated images for simulations and experimental investigation show good agreement, and show the presence of tumour with good location accuracy. Measurements indicate that both prototype microwave sensors are good candidates for tested imaging applications.

Ce travail vise à comprendre l’évolution de la texture cristallographique et l’anisotropie du comportement mécanique après laminage à chaud et traitements thermiques d’un Al-Cu-Li 2050 et d’un Al-Zn-Mg-Cu 7050, et expliquer leurs différences. La texture est analysée par EBSD et RX après des essais de compression plane à chaud et après des laminages à chaud industriels. L’anisotropie est étudiée sur des tôles fortes industrielles après différents détensionnements et dans différents états microstructuraux par des essais de traction à 0°, 45° et 90° par rapport à DL. Enfin, nous comparons nos mesures à des résultats simulés par des modèles de plasticité cristalline (modèles de Taylor). Il est montré que, déformés dans des conditions identiques, les deux alliages développent les mêmes textures de laminage jusqu'à une déformation de 2.6. La présence de 1% massique de Li n’est à priori pas responsable d’une texture particulière. En revanche la température de laminage, qui est généralement plus élevée pour les Al-Cu-Li que pour les Al-Zn-Mg-Cu, a un impact important aux grandes déformations, notamment en favorisant la composante Laiton {110}<112>. L'anisotropie d'une tôle laminée de 2050 est pour une large part due à la texture cristallographique. Elle augmente quand un détensionnement est effectué par traction dans la direction DL et diminue quand il est effectué à 45°/DL. La précipitation durcissante, composée de T1 Al2CuLi en forme de plaquettes sur les plans {111}Al, augmente la résistance de la direction préalablement tractionnée mais n'est pas responsable dans nos conditions expérimentales d'une forte aggravation de l'anisotropie. Dans le 7050, l'anisotropie diminue entre l’état mûri naturellement et l’état sur-revenu. La précipitation de sur-revenu du 7050 atténue l'effet de la texture cristallographique sur l'anisotropie et rend, en comparaison, le 2050 d’autant plus anisotrope. / This work aims to understand hot rolling texture evolution and anisotropy of mechanical behaviour on an Al-Cu-Li 2050 and an Al-Zn-Mg-Cu 7050, and aims to explain their differences. Crystallographic textures are analysed by EBSD and X-ray after hot plane strain compressions and after industrial hot rolling. Anisotropy of industrial hot rolled plates is investigated after different stretching and different ageing treatments by means of tensile tests at 0°, 45° and 90° to RD. Experimental results are compared to predictions using plasticity models (Taylor models). It is shown that, under the same processing conditions, the two alloys develop the same rolling textures up to strain of 2.6 ; it can be concluded that the presence of 1wt% of Li does not by itself favour a particular texture. However, it is shown that Brass component {110}<112> is favoured by an increasing rolling temperature, which is generally higher in the Al-Cu-Li than in the Al-Zn-Mg-Cu. Anisotropy of hot rolled 2050 is for a large part caused by crystallographic texture. It increases when stretch axis is at 0° and decreases when stretch axis is at 45°. Hardening precipitation, made by plate shape T1 Al2CuLi lying on the {111}Al, increases yield strength in the stretched direction but it is not responsible in our experimental conditions for a high increase of anisotropy. Anisotropy of 7050 is less important in the over aged state than in the natural aged state. Over ageing precipitation of 7050 reduces the effect of crystallographic texture on the anisotropy and makes 2050 appearing much more anisotropic.

This diploma thesis solves possibilities of utilization optical fiber as sensor. At the beginning, basic division of this sensors is desribed, their principles and usage. Then the thesis is focused on distributed sensors based on the interference of the light, interferometers. This optic fiber interferometers are described, mainly their modifications for detection and localization of vibrations along optical fiber. Significant part of the thesis deals with dual Mach--Zehnder interferometer. This interferometer is theoreticaly desribed and simulated in Matlab. Further the thesis deals with development of two aplication in Matlab software. One application is for simulation and theoretical computation of dual Mach--Zehnder interferometer. Second application serves for signal processing of acquired data that are measured on this interferometer. At the end of the thesis, dual Mach--Zehnder interferometer is designed and build in laboratory enviroment and executed measurement and localization of vibrations using this interferometer.

The dissertation thesis deals with signal detection by an ionization detector in the environmental scanning electron microscope and utilization of this detector to gain required information in a specimen image. Main interest is focused on the detector containing several electrodes with a varied geometry arrangement and voltages on these electrodes. The detector was named segmental ionization detector. Detection capabilities of the segmental ionization detector were studied through computer simulations and experiments in the microscope utilizing knowledge from a technical literature background. On the base of the accomplished experiments, the segmental ionization detector has been optimized for the secondary electron detection improvement and at another configuration optimized for a high material contrast acquisition of the specimen image. Consideration of benefits of the examined segmental ionization detectors is included in the work.

Thesis deals with environmental scanning electron microscopy and with detection of signal electrons by using ionization detector. First part talks about the principle of environmental scanning electron microscope. Second part describes signals generated by interaction of primary electron beam with sample. Third section explains the principle of impact ionization and ionization detector. Experimental part deals with usage of segmental ionization detector and with measuring of signal amplification from copper and platinum. Thesis also examines arrangement of electrodes of ionisation detector on material contrast and examines also on influence of voltage contrast on base - emitter junction of an NPN bipolar transistor. All experiments were carried out in dependency on saturated water vapour pressure in sample chamber.

This work deals with the evaluating of the signal level value from the sample in the environmental SEM. In work there were processed the comparison of the osciloscopic method for the evaluating of the signal level value in the environmental SEM, the method for the evaluating of the signal level from the grey level of the sample images and the method for the evaluating of the signal level from the osciloscop. There are described the advantages and disadvantages of the methods and procedures for processing the methods.

Thesis deals with environmental scanning electron microscopy and with detection of signal electrons by using ionization detector. First part talks about the principle of environmental scanning electron microscope. Second part describes signals generated by interaction of primary electron beam with sample. Third section explains the principle of impact ionization and ionization detector. Experimental part deals with usage of segmental ionization detector and with measuring of signal amplification from copper and platinum. Thesis also examines arrangement of electrodes of ionisation detector on material contrast and examines also on influence of voltage contrast on base - emitter junction of an NPN bipolar transistor. All experiments were carried out in dependency on saturated water vapour pressure in sample chamber.