No (1095)
Yes (7)
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Silver micro drop structured twice around the earth
Meluzín, Petr; Tryhuk, V.; Horáček, Miroslav; Knápek, Alexandr; Krátký, Stanislav; Matějka, Milan; Kolařík, Vladimír
2018 - English
Planar micro structuring of thin metallic layers allows to achieve required surface properties of metallic layers covering bulk materials. Recently, the arrangement of micro holes or pillars placed around the primary spiral according to a phyllotactic model was presented. This deterministically aperiodic planar arrangement was used for benchmarking purposes of the e-beam writer patterning. This arrangement based on single primary spiral and a variety of derived secondary spirals has several interesting properties. One of them is a very low ratio between the area populated by individual micro elements and the length of the primary phyllotactic spiral. This paper presents analysis of the phyllotactic spiral length and the rising gradient at the spiral outer edge. The practical part of the presented work deals with the patterning of a thin silver layer deposited on the silicon or glass substrates using e-beam pattern generation, lithography techniques and related technologies. An interesting impact of the mentioned spiral properties on the e-beam writing strategies and the exposure ordering strategy are also discussed.
Keywords:
metallic thin layer; planar surface structure; phyllotactic spiral; e-beam writer
Available at various institutes of the ASCR
Silver micro drop structured twice around the earth
Planar micro structuring of thin metallic layers allows to achieve required surface properties of metallic layers covering bulk materials. Recently, the arrangement of micro holes or pillars placed ...
Synergic effects of laser – TIG welding
Kubíček, J.; Doležal, P.; Mrňa, Libor; Šebestová, Hana; Horník, Petr
2018 - Czech
Laser welding compared to conventional arc methods is accompanied by rapid cooling rates. It can lead to the formation of undesirable microstructure of the weld metal and heat affected zone of some steel grades which has a negative impact on their mechanical properties. The preheating is quite problematic because of high speed of laser welding. The possibility of preheating by the heat of the arc discharge of the associated TIG burner has been tested. Precise holder has been fabricated to fix the burner to the laser welding head allowing TIG electrode positioning towards the laser beam and the workpiece. A number of high strength steel S460MC and S700MC welding experiments was performed. The effect of TIG current on microstructural changes has been proven. Some welding experiments were compared to the SYSWELD welding simulations.\n Laserové svařování ve srovnání s konvenčními obloukovými metodami je doprovázeno rychlou rychlostí chlazení. To může vést ke vzniku nežádoucí mikrostruktury svařovaného kovu a tepelně postižené zóny některých ocelových tříd, což má negativní dopad na jejich mechanické vlastnosti. Předehřívání je poměrně problematické kvůli vysoké rychlosti svařování laserem. Byla testována možnost předehřívání teplem z obloukového výboje přidruženého hořáku TIG. Přesný držák byl vyroben pro upevnění hořáku na laserovou svařovací hlavu, umožňující umístění TIG elektrody směrem k laserovému paprsku a obrobku. Byla provedena řada ocelových zkoušek S460MC a S700MC s vysokou pevností. Účinek proudění TIG na mikrostrukturální změny byl prokázán. Některé svařovací experimenty byly porovnány s simulacemi svařování SYSWELD.
Keywords:
laser – TIG welding; cooling rate; HSLA steels; microstructure; tensile strength
Available at various institutes of the ASCR
Synergic effects of laser – TIG welding
Laser welding compared to conventional arc methods is accompanied by rapid cooling rates. It can lead to the formation of undesirable microstructure of the weld metal and heat affected zone of some ...
Recent Trends in Charged Particle Optics and Surface Physics Instrumentation. Proceedings of the 16th International Seminar
Mika, Filip; Pokorná, Zuzana
2018 - English
The origins of the seminar “Recent Trends in Charged Particle Optics and Surface Physics Instrumentation” date back into the eighties, when as a part of the isolated “Eastern Bloc”, we were short of English-language books, papers and conferences. In 1990, at the second Seminar, there were as many as 30 participants from 5 countries. The third Seminar in 1992 was moved to hotel Skalský dvur in the Bohemian-Moravian Highlands where it has been held as a biannual meeting ever since.\nThe Seminar takes place in a secluded lakeside hotel surrounded by beautiful nature and calm forests, so all participants have a great possibility to see each other every day and to discuss their topics of interest in more detail. This is a great advantage compared to the huge bustling conferences with their many parallel sections, which are a lively celebration of science but\nsometimes it is difficult to meet there the person with whom you want to discuss a particular scientific topic in more detail.\nFrom the very beginning, the Seminar has been conceived as a meeting devoted more to asking questions not answered yet, than to reporting results. This spirit is usually less present in the introductory presentations and posters but is dominant in the following discussions.\n
Keywords:
charged particle optics; surface physics; instrumentation
Available at various institutes of the ASCR
Recent Trends in Charged Particle Optics and Surface Physics Instrumentation. Proceedings of the 16th International Seminar
The origins of the seminar “Recent Trends in Charged Particle Optics and Surface Physics Instrumentation” date back into the eighties, when as a part of the isolated “Eastern Bloc”, we were short of ...
Very low energy electron transmission spectromicroscopy
Daniel, Benjamin; Radlička, Tomáš; Piňos, Jakub; Mikmeková, Šárka; Konvalina, Ivo; Frank, Luděk; Müllerová, Ilona
2018 - English
For more than 25 years, Scanning Low Energy Electron Microscopy (SLEEM) has been\ndeveloped at the Institute of Scientific Instruments (ISI), with several commercially available SEMs adapted with a cathode lens for SLEEM use, as well as a dedicated self-built UHVSLEEM setup.\nFor a better understanding of contrast formation at low energies, especially at very low energies below 50 eV, where the local density of states plays an important role, more general knowledge about the interaction of (very) low energy electrons with solids is required. This will be achieved using a newly developed ultra-high vacuum (UHV SLEEM) setup which includes several enhancements compared to other available machines. Data processing is presented in, and processed data will be further used and tested with the Monte Carlosimulation package BRUCE, which is being developed by Werner et al. at TU Vienna.
Keywords:
low energy scanning electron microscopy; electron microscopy; time of flight; electron energy lost spectroscopy
Available at various institutes of the ASCR
Very low energy electron transmission spectromicroscopy
For more than 25 years, Scanning Low Energy Electron Microscopy (SLEEM) has been\ndeveloped at the Institute of Scientific Instruments (ISI), with several commercially available SEMs adapted with a ...
SMV-2018-12: Development of welding and brazing joints for mechanical assemblies
Zobač, Martin; Vlček, Ivan; Dupák, Libor
2018 - Czech
The subject of the project was further research and development of permanent joints of metal materials by electron beam welding and development of procedures of temperature stabilisation of metal part. The outcome of the project were specific technological procedures for the given assemblies. The significant experimental demands were characteristic for this project. Předmětem řešeného projektu byl další výzkum a vývoj nerozebiratelných spojů kovových materiálů s využitím technologie svařování elektronovým svazkem a vývoj postupů teplotní stabilizace kovových dílů. Výsledkem projektu byly konkrétní technologické postupy pro konkrétní sestavy. Pro daný projekt byla charakteristická značná experimentální náročnost.
Keywords:
electron beam welding; vacuum brazing; temperature stabilisation
Available at various institutes of the ASCR
SMV-2018-12: Development of welding and brazing joints for mechanical assemblies
The subject of the project was further research and development of permanent joints of metal materials by electron beam welding and development of procedures of temperature stabilisation of metal ...
SMV-2018-13: Research and development of electron guns designed for welding
Zobač, Martin; Vlček, Ivan; Dupák, Libor
2018 - Czech
The subject of the project was further research and development of the electron gun for electron beam welding. The improvements were aimed to specific components from which are the electron guns assembled. A series of samples was produced for the product evaluation. Předmětem projektu bylo pokračování výzkumu a vývoje trysek pro elektronové svařování a příslušenství. Probíhající fáze byla zaměřena na úpravy dílčích součástí trysek. Pro otestování modifikací byly vyrobeny ověřovací vzorky.
Keywords:
electron gun; electron beam welding machine
Available at various institutes of the ASCR
SMV-2018-13: Research and development of electron guns designed for welding
The subject of the project was further research and development of the electron gun for electron beam welding. The improvements were aimed to specific components from which are the electron guns ...
SMV-2018-07: Design, development and experimental depostion of interference filter and mirror samples
Oulehla, Jindřich; Pokorný, Pavel
2018 - Czech
Development of various beam splitters/combiners and mirrors including antireflective coatings for 45° incidence and test sample deposition. Vývoj různých druhů beam splitterů/combinerů a zrcadel včetně antireflexních vrstev pro dopad světla 45° a depozice jejich funkčních vzorků.
Keywords:
thin film optics; interference filters; e-beam evaporation
Available at various institutes of the ASCR
SMV-2018-07: Design, development and experimental depostion of interference filter and mirror samples
Development of various beam splitters/combiners and mirrors including antireflective coatings for 45° incidence and test sample deposition.
Measurement of laser welding process by high-speed camera and photodiode
Horník, Petr; Mrňa, L.; Šebestová, Hana
2018 - Czech
Laser welding monitoring system can be realized optically. The solution with photodiode sensing welded area has advantage of simplicity and low cost but faces many challenges. Multi-photodiode measurement show dependency of the measured intensity on the photodiode position. Subsequently, the measured values were compared with high-speed camera images. Using the correlation coefficient, the area providing the same information as photodiode measurement was determined in the images. Systém pro monitorování laserového svařovacího procesu lze realizovat opticky. Řešení pomocí fotodiod snímajících svařované místo má výhodu v jednoduchosti a nízkých nákladech, potýká se však s mnoha výzvami. Při snímání více fotodiodami byla zjištěna závislost měřené intenzity na poloze fotodiody. Následně byly naměřené hodnoty porovnány se snímky vysokorychlostní kamery. S využití korelačního koeficientu byla na snímcích určena oblast poskytující stejnou informaci jako měření fotodiodou.
Keywords:
laser welding; process monitoring
Available at various institutes of the ASCR
Measurement of laser welding process by high-speed camera and photodiode
Laser welding monitoring system can be realized optically. The solution with photodiode sensing welded area has advantage of simplicity and low cost but faces many challenges. Multi-photodiode ...
SMV-2018-20: Electron optical propertis of the multibeam electron source
Radlička, Tomáš
2018 - Czech
The electron beam is generated in the field-emission electron source and it is separated to number of indiviual beamlets in the aperture array containg 14x14 small apertures – aperture lenses. We studied possible correction of field curvature and astigmatism as well as influence of surrounding apertures on the properties of the electron beam. Elektronový svazek je generovaný v jednom auto-emisním elektronovém zdroji, a na jednotlivé se svazečky se rozdělí na speciální apertuře, na které je 14x14 malých kruhových aperturek. Ty zároveň fungují jako čočky pro každý svazeček. Byla studována možnost korekce sklenutí pole a astigmatizmu a vzájemný vliv jednotlivých aperturek pomoci 3D výpočtu pole.
Keywords:
electron source; multi-beam SEM
Available at various institutes of the ASCR
SMV-2018-20: Electron optical propertis of the multibeam electron source
The electron beam is generated in the field-emission electron source and it is separated to number of indiviual beamlets in the aperture array containg 14x14 small apertures – aperture lenses. We ...
Comparison of frequency stability of laser wavelength standards over photonic networks
Pravdová, Lenka; Hrabina, Jan; Čížek, Martin; Lazar, Josef; Číp, Ondřej
2018 - Czech
In our work we present a metrological ampaign in which the stability of the 1540 nm normal laser located at the CESNET workplace in Prague was compared with the wavelength of the supercoherent laser transmitted from the ÚPT workplace in Brno via the 306 km phase-coherent transfer line Brno - Prague. The assembled acetylene standard was transferred to the CESNET workplace and a unit receiving coherent wave from the supercoherent laser stabilized by the optical frequency comb and the H-maser at the ISI workplace in Brno was put into operation. The optical frequency mixer with a photodetector recorded a frequency response between the acetylene optical frequency normal and the supercoherent laser distributed over the photonic network whose stability is given by the H-maser in the 15th order. We have verified that the laser normal meets the requirements of the BIMP Recommendation for the Practical Implementation of the Meter Standard. V naší práci představujeme metrologickou kampaň, ve které byla porovnávána stabilita normálového laseru na vlnové délce 1540 nm, umístěného na pracovišti CESNET v Praze s vlnovou délkou superkoherentního laseru přenášenou z pracoviště ÚPT v Brně přes fázově koherentní přenosovou linku Brno – Praha délky 306 km. Sestavený acetylenový normál byl převezen na pracoviště CESNET a zároveň byla uvedena do provozu jednotka příjmu koherentní vlny ze superkoherentního laseru stabilizovaného optickým frekvenčním hřebenem a H-maserem na pracovišti ÚPT v Brně. Optickým směšovačem s fotodetektorem byl zaznamenán frekvenční průběh záznějové frekvence mezi acetylenovým optickým frekvenčním normálem a superkoherentním laserem distribuovaným přes fotonickou síť, jehož stabilita je dána H-maserem v 15. řádu. Ověřili jsme, že laserový normál splňuje požadavky Recommendation for the practical realization of the meter standard BIMP.
Keywords:
metrology; optical normal; photonic networks
Available at various institutes of the ASCR
Comparison of frequency stability of laser wavelength standards over photonic networks
In our work we present a metrological ampaign in which the stability of the 1540 nm normal laser located at the CESNET workplace in Prague was compared with the wavelength of the supercoherent laser ...
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