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Trajektorie signálních elektronů v nízkonapěťovém BSE detektoru
No full textNowadays the development of the image formation in scanning electron microscope (SEM) is oriented to the use of scanning electron microscopes with low accelerating voltage of the primary beam (LV SEM). Secondary electrons (SEs) for topographical contrast observation and backscattered electrons (BSEs) for material contrast observation are the main components of the detected signal in LV SEM. While the secondary electrons can be detected either by Everhart-Thornley scintillation detector or by the "in lens" SE detector, the detection of backscattered electrons (BSEs) in LV SEM is an unsolved problem ye
Pozorování zubní skloviny a dentinu v SEM
No full textThe purpose of this study was to investigate whether the acidic monomer based on the phosphoric acid ether acrylate can create the same retentive pattern in enamel and dentin as the conventional treatment with the 37% phosphoric acid. The surface of enamel in the AdHeSe group was slightly undulated, the retentive pattern was regular and moderate. In the TotalEtch group more irregularities and a clearer retentive pattern were observed. The dentin surface was similar in both groups- it was clean without the smear layer, the dentin tubuli were open, the collagen network was seen on the dentin surface as well as in the dentin tubuli
Detekce signálních elektronů v nízkonapěťové SEM
No full textThis paper deals with the detection of signal electrons in the SEM at primary beam energies of 3 keV and less. Special attention is paid to the detection of backscattered electrons which is at low primary beam energies very problematic
Pozorování nevodivých nano-struktur v rastrovacím elektronovém mikroskopu
No full textThis paper deals with the observation of the non-conductive samples in the scanning electron microscope by the method of the critical energy finding by the cathode lens system and by the low energy backscattered electron detector. Both methods are described in detail and their advantages are shown by imaging of various non-conductive samples
Collection solid angle of backscattered electrons in environmental scanning electron microscopy
No full textThis paper deals with an influence of the collection solid angle on a magnitude of detected signal. The presented results of measurement were gained by an observation of the specimen of carbon covered with a thin layer of gold. The collection solid angle was changed by application of aluminium masks mounted on the scintillator. As a working environment in the specimen chamber air and saturated water steam were used
Detection of Backscattered Electrons in Low Voltage Scanning Electron Microscopy
No full textThis paper deals with the problems of backscattered electrons (BSE) detection in low voltage scanning electron microscopy (LV SEM). The BSE energy is 3 keV and less in LV SEM. This low BSE energy causes problems with the acquisition of sufficient signal for the image. It is necessary to accelerate BSE and separate SE to obtain applicable specimen image
Výpočty nízkonapěťového BSE detektoru
No full textThe scintillator-photomultiplier detection system installed under the pole piece represents the most efficient BSE detector in SEM. However, the initial energy of the BSEs of 0.5-3 keV in the LV SEM is the energy, on which the light yield of scintillators decreases. Appropriate acceleration of BSEs and declination of SEs is necessary for the best BSE image at low acceleration voltage. Electrostatic field affecting signal electron trajectories was simulated in the software package Simion 3D
Study of contrast mechanisms in environmental scanning electron microscopy
No full textThe main goal of the work is study of contrast materials in environmental scanning electron microscopy. I will concentrate to the design and construction of the original detector of secondary electrons, which is not influenced by backscattered electrons as well as to scintillation detector of backscattered electrons on the basis of single-crystal YAP in the dissertation work. For successful solution of the topic it will be necessary to manage the theory of the influence of magnetic fields on trajectories of electrons. The knowledge of the software SIMION, version 7.0 will be necessary too, together with studying of the theory for assessment of suitable vacuum conditions in differential chambers
Nový detektor zpětně odražených elektronů pro nízkonapěťový SEM
No full textThis work deals with the description of the new scintillation detector of backscattered electrons for the low voltage scanning electron microscope
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