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Elektrostatické vychylovací a korekční systémy
Badin, Viktor ; Oral, Martin (oponent) ; Zlámal, Jakub (vedoucí práce)
Tato diplomová práce se věnuje prozkoumání možností dynamické korekce vad v elektronové litografii. Pro výpočty byl zvolen elektronový litograf BS600. Práce se zabývá korekcí vad vychýlení třetího řádu: zklenutí pole, astigmatismu a zkreslení. Aberace byly spočteny jak pro současný magnetický vychyolvací systém, tak pro nově navržený elektrostatický deflektor. Vlastnosti a vady obou vychylovacích a korekčních systémů byly porovnány.
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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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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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Inelastic mean free path from raw data measured by low-energy electrons time-of-flight spectrometer
Zouhar, Martin ; Radlička, Tomáš ; Oral, Martin ; Konvalina, Ivo
The inelastic mean free path (IMFP) is a key parameter of electron transport in a solid. With\nthe rise of so-called meta-materials, materials of specific shape, such as 2D crystals, or\nmaterials with tailored functionality for next-generation electronic devices, the investigation\nof the IMFP is still topical and of high importance. This is true especially at low energies, landing energy of electrons below 100 eV, that are hard to study using well established\ntechniques of electron spectroscopy.
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Electron optical properties of a new low-energy scanning electron microscope with beam separator
Radlička, Tomáš ; Kolařík, V. ; Oral, Martin
The low energy scanning electron microscope (SEM) which is currently at the Institute of\nScientific Instruments, suffers from low resolution and suboptimal detections systems. In the cathode lens regime, signal electrons are accelerated by the electric field between the sample and the objective lens, getting collimated. Those with low emission angles get through the bore in the BSE detector into the objective lens and cannot be detected by the available detectors now. The information about the sample provided by these electrons is lost, which limits our microscopy methods.\nThese two limitations are to be overcome with a new low-energy SEM, which was developed\nat Delong Instruments. It consists of a field emission gun with the energy width of 0.8 eV, a magnetic condenser lens, and an electrostatic triode objective lens. The acceleration voltage is 5 kV. The sample stage can be biased at up to -5 kV to provide low landing energy without strong decrease of the resolution – the effect of the cathode lens. A beam separator is placed in front of the deflection system for the detection of the signal electrons that get to the column. In a combination with standard detectors and cathode lens, it allows detecting all\nkinds of signal electrons.
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Analysis of linear ion Paul traps using 3-D FEM and the azimuthal multipole expansion
Oral, Martin ; Číp, Ondřej ; Slodička, L.
Radiofrequency (RF) Paul traps are valuable in the design and in the operation of highly stable\noptical atomic clocks based on suitable trapped ions. The traditional setup involves a single\nion in an RF trap irradiated with a laser beam. The frequency of the laser light is then fine-tuned to match that of photons coming from an electronic transition in the atomic shell. The\nachievable frequency stability is about 10-17 for laser-cooled ions. However, the stability can be\nfurther improved by using heavy atoms (such as Thorium) and the more stable frequencies of\ntheir nuclear transitions, and by setting up so-called Coulomb crystals, to improve the frequency measurement statistics by increasing the number of reference atoms. These techniques and their combination could reach relative stabilities beyond 10-20.
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Degradace motorového oleje ve vznětovém motoru osobního automobilu
Oral, Martin
Diplomová práce je zaměřena na problematiku degradace motorových olejů stejné viskózní třídy 5W-30. První část je zaměřena na mazací systémy a jejich dílčí části. Dále se práce zaměřuje na rozdělení olejů do jednotlivých klasifikací a popis vlastností. Vzorky oleje pochází ze dvou osobních automobilů, které mají totožný vznětový motor, avšak jiný celkový nájezd kilometrů. Dále je věnována pozornost množství konstrukčních kovů, aditiv a kontaminantů v obou olejích, a to v průběhu celého servisního intervalu výměny olejů. Získané výsledky jsou interpretovány graficky a jednotlivé závislosti jsou modelovány pomocí vhodných regresních funkcí. Diplomová práce porovnává mechanické a fyzikální vlastnosti motorových olejů v závislosti na množství ujetých kilometrů. Závěr práce shrnuje vyhodnocení a získané výsledky.
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Correction of misalignment aberrations of a hexapole corrector using the differential algebra method
Radlička, Tomáš ; Oral, Martin
Overcoming the limitations of the Schertzer theorem is a long story in electron microscopy. Although the basic principle of a spherical aberration (C3) correction was suggested as early as in 1947 the first experimental correctors of spherical aberration were only realized in the last decade of the 20th century. The recent multipole correctors are designed for high-energy\nTEM or STEM, where the corrector system enables reaching the atomic resolution. On the other\nhand, the corrector for low-energy SEM has been developed but this type of corrector must also contain chromatic aberration (Cc) correction to reduce the effect of the non-zero energy width. Recently, the energies of SEM reach 30 keV and transmission mode (TSEM) is a standard part of the instrument. Standard resolution in TSEM is about 0.6 nm and it is limited by C3. Reaching atomic resolution with this set-up is not a real expectation because of its instability, but the resolution of about 0.2 nm would increase the field of applications. Corrector for these type of instruments should be (a) simple, compact and cheap (b) only spherical aberration of the third,\noptionally the fifth order must be corrected (c) effect of the chromatic aberration may be reduced by energy filtering. We studied design based on Rose’s hexapole corrector.
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