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Multi-electrode system of ionization detector for environmental scanning electrone microscope
Uhlář, Vít ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
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.
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Ionization detector for ESEM
Pokluda, Tomáš ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
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.
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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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Contrast in image aquired by scintillation SE detector for VP SEM
Koudela, Oldřich ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
First part of this thesis is a theoretical essay which deals with the basics of scanning electron microscopy, with structure and function of a scanning electron microscope, its’ special case of an various pressure scanning electron microscope, electron interaction with surrounding environment and with a scintillation detector. The applied part of the thesis is focused on evaluation of material contrast on Cu-W specimen. Material contrast is evaluated for different pressures of water vapors in the microscope specimen chamber and for different detection conditions.
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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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Scintillation SE Detector with Controlled Gas Flow for VP SEM
Kozák, Josef ; Neděla, Vilém (referee) ; Jirák, Josef (advisor)
This master’s thesis deals with a design and optimization of an experimental scintillation secondary electron detector for the environmental scanning electron microscope and with a description of a detector operation principle. The experiment is founded on simulations of a gas flow in detector inner sections and on simulations of secondary electron trajectories in electrostatic fields of the detector. On the basis of the simulations, new solutions of the detector designs are proposed. For these designs, same simulations as previous are performed and designs that seem to be feasible for the secondary electron detection in environmental scanning electron microscope are selected.
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Scintillation SE Detector for Variable Pressure SEM
Tihlaříková, Eva ; Neděla, Vilém (referee) ; Jirák, Josef (advisor)
This project deals with the theme of environmental scanning electron microscopy (EREM). This method allows the examination of insulators and wet specimens without pretreatment and modification like drying and metallization. The principle of this method consists in using higher pressure in a specimen chamber. The pressure is within the range of 100 – 200 Pa. However, the pressure in the specimen chamber restricts the signal detection interference. The objective of the work is to explore the possibility of interference in secondary electron route detection by way of electrostatic field. The electrostatic field was realized with the system consisting of four electrodes located in front of the scintillation detector. It should have interfered the secondary electron´s trajectory to the detector chamber. The optimization of voltage on the electrodes was made by simulation program called SIMION. The simulation results were experimentally verified with laboratory EREM.
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Ionization Detector for Variable Pressure SEM
Černoch, David ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
This graduation theises deal with influence of an additional grating possitioned berween the sample and the ionisation detektor of the environmental scannin elektron microscope on signal detection. Signal level is measured for changing pressure, at different voltages on the aditional grating, at different sample - additional electrode distance and at different sample - detektor distance. Influence of the additional grating is simulated for real working conditions on PC.
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Scintillation Detector of Secondary Electrons for ESEM
Čudek, Pavel ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
The thesis deals with modifying and biulding of scintilation detector of secondary electrons for environmental scanning electron microscopy. It describes dilemma of environmental scanning electron microscopy, types of detectors and secondary electrons detection. The experimental part of this thesis focuses on the design and construction of new scintillation detector on the basis of simulations secondary electrons trajectories. Identifying the parameters, pressure dependencies and optimizations of electrode system of the detector realized.
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