Number of found documents: 650
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Imaging via multimode optical fiber: recovery of a transmission matrix using internal references
Šiler, Martin; Jákl, Petr; Traegaardh, Johanna; Ježek, Jan; Uhlířová, Hana; Tučková, Tereza; Zemánek, Pavel; Čižmár, Tomáš
2018 - English
Current research of life shows a great desire to study the mechanics of biological processes\ndirectly within the complexity of living organisms. However, majority of practical techniques\nused nowadays for tissue visualization can only reach depths of a few tens of micrometres as\nthe issue obscures deep imaging due to the random light scattering. Several imaging\ntechniques deal with this problems from different angels, such as optical coherence\ntomography, light sheet microscopy or structured light illumination A different and promising strategy to overcome the turbid nature of scattering tissues is to employ multimode optical fibers (MMF) as minimally invasive light guides or endoscopes to provide optical access inside. Although the theoretical description of light propagation through such fibers has been developed a long time ago it is frequently considered inadequate to describe real MMF. The inherent randomization of light propagating through MMFs is typically attributed to undetectable deviations from the ideal fiber structure. It is a commonly believed that this\nadditional chaos is unpredictable and that its influence grows with the length of the fiber.\nDespite this, light transport through MMFs remains deterministic and can be characterized by a transmission matrix (TM) which connects the intensity and phase patterns on the fiber input and output facets. Once the TM is known it can be used to create focus in any desired 3D\ncoordinates beyond the distal fiber facet, see figure 1, and perform e.g. fluorescence based\nlaser scanning microscopy or optical trapping. Keywords: multimode optical fiber Available at various institutes of the ASCR
Imaging via multimode optical fiber: recovery of a transmission matrix using internal references

Current research of life shows a great desire to study the mechanics of biological processes\ndirectly within the complexity of living organisms. However, majority of practical techniques\nused ...

Šiler, Martin; Jákl, Petr; Traegaardh, Johanna; Ježek, Jan; Uhlířová, Hana; Tučková, Tereza; Zemánek, Pavel; Čižmár, Tomáš
Ústav přístrojové techniky, 2018

Electron beam welding at ISI Brno
Dupák, Libor; Zobač, Martin; Vlček, Ivan; Zobačová, Jitka
2018 - English
In vacuum technology, and especially in UHV, we often encounter the necessity of joining\nparts of various metals in combination with the demand for perfect vacuum tightness,\ncleanness of joints and minimum deformations. Electron beam welding belongs to the\nbest technologies capable of fulfilling such requirements.\nThe principle of electron beam welding is based on the transfer of the kinetic energy of the\nincident accelerated electrons to the welded material in the form of heat. The temperature in\nthe spot rises with the beam power density. At power densities as high as 104 - 106 W/mm2,\nthe melted material at the center of the focal point evaporates. This produces a vapor capillary surrounded by melted material that allows the beam to penetrate deeper and melt more material. The speed of the penetration can be much higher than the heat transfer by\nconduction into the surrounding material. This results in narrow melted area and typical knifelike\nprofile of the weld. Thanks to this effect the thermal deformations of welded\npieces are highly reduced to almost none. Small heat affected zone also allows welding near\nheat sensitive parts like sensors, ceramic feed-throughs and brazed joints. Keywords: electron beam welding Available at various institutes of the ASCR
Electron beam welding at ISI Brno

In vacuum technology, and especially in UHV, we often encounter the necessity of joining\nparts of various metals in combination with the demand for perfect vacuum tightness,\ncleanness of joints and ...

Dupák, Libor; Zobač, Martin; Vlček, Ivan; Zobačová, Jitka
Ústav přístrojové techniky, 2018

Possibilites of a secondary electrons bandpass filter for standard SEM
Mika, Filip; Pokorná, Zuzana; Konvalina, Ivo; Khursheed, A.
2018 - English
Secondary electron filtering in Scanning Electron Microscope (SEM) has been in use for over\na decade. This technique uncovers interesting contrasts in an otherwise ordinary SEM image\nwhich can possibly be used for dopant concentration mapping or for discerning the slight molecular weight differences in apparently homogeneous organic materials. Secondary\nelectron filtering of semiconductor samples seems very promising as it may shed light on the mechanism of SEM image contrast between p-doped and n-doped semiconductors, possibly\nallowing to determine dopant concentration from SEM image alone. Keywords: secondary electron; filtering; imaging Available at various institutes of the ASCR
Possibilites of a secondary electrons bandpass filter for standard SEM

Secondary electron filtering in Scanning Electron Microscope (SEM) has been in use for over\na decade. This technique uncovers interesting contrasts in an otherwise ordinary SEM image\nwhich can ...

Mika, Filip; Pokorná, Zuzana; Konvalina, Ivo; Khursheed, A.
Ústav přístrojové techniky, 2018

Secondary electron hyper spectral imaging in helios nanolab - mapping materials properties or artefacts?
Rodenburg, C.; Masters, R.; Abrams, K.; Dapor, M.; Krátký, Stanislav; Mika, Filip
2018 - English
A link between peaks in secondary electron (SE) spectra and Electron Energy Loss Spectra\n(EELS) was shown decades ago. Also, materials properties (bulk modulus, band gap)\ncorrelate with the bulk plasmon position in EELS, and local modulus maps in carbon fibres\nhave been presented. If any features as result of plasmon decay into SE can be identified,\nSE spectroscopy combined with hyperspectral imaging could transform the SEM into a tool\nfor mapping materials properties with ground-breaking potential for nanotechnology. To\nbecome a reality, we first need to establish SE collection conditions spectra that represent a\nmaterial reliably. Second, we need to gain a better understanding of the processes involved in the SE emission processes. Keywords: secondary electrons; polymers; hyperspectral imaging Available at various institutes of the ASCR
Secondary electron hyper spectral imaging in helios nanolab - mapping materials properties or artefacts?

A link between peaks in secondary electron (SE) spectra and Electron Energy Loss Spectra\n(EELS) was shown decades ago. Also, materials properties (bulk modulus, band gap)\ncorrelate with the bulk ...

Rodenburg, C.; Masters, R.; Abrams, K.; Dapor, M.; Krátký, Stanislav; Mika, Filip
Ústav přístrojové techniky, 2018

Thickness determination of a cathodoluminescence active nanoparticles by means of Quantitative STEM imaging
Skoupý, Radim; Krzyžánek, Vladislav
2018 - English
Labeling of specimens by nanoscale probes is common approach of complex biological\nsystems exploration. Namely gold nanoparticles immuno-staining is well established method\nin electron microscopy. However, if more than two label sizes are used, the differentiation of\nindividual nanoparticles becomes difficult.\nThis can be overcome by cathodoluminescence (CL) active particles – nanophosphors where\nlabels recognition is done by wavelength of emitted light. This gives a great opportunity to\nuse advanced multi probe labeling within one sample.\nThere is a huge variety of nanophosphors: green fluorescent protein, quantum dots, ZnO\nnanoparticles, organic molecules, rare earth-doped nanophosphors etc. Therefore, in order\nto choose best type of nanophosphors for a given task, it is important to measure particles\nsize/thickness, as the CL intensity is proportional to the probe volume. Keywords: quantitative imaging; Monte Carlo Available at various institutes of the ASCR
Thickness determination of a cathodoluminescence active nanoparticles by means of Quantitative STEM imaging

Labeling of specimens by nanoscale probes is common approach of complex biological\nsystems exploration. Namely gold nanoparticles immuno-staining is well established method\nin electron microscopy. ...

Skoupý, Radim; Krzyžánek, Vladislav
Ústav přístrojové techniky, 2018

Gel Polymer Electrolytes Modified Nanoparticles or Copolymers and Polymerized in Magnetic and Electric Fields
Jahn, M.; Veselková, I.; Sedlaříková, M.; Zatloukal, M.; Bartušek, Karel
2018 - English
Gel polymer electrolytes are perspective electrolytes for new types of Li-ion batteries today. The properties respectively advantages of these gels can be used also in other fields of electrochemistry. The gel polymer electrolyte is composed of a conductive component (liquid electrolyte) and the polymer component (methacrylate-based polymer). In this paper, I present fundamental characteristics of gel polymer electrolytes modified nanoparticles or copolymers and preparation of these gel polymer materials with nanoparticles or copolymers polymerized in electric and magnetic fields. Keywords: magnetic and electric fields; gel polymer electrolytes; nanoparticles Available at various institutes of the ASCR
Gel Polymer Electrolytes Modified Nanoparticles or Copolymers and Polymerized in Magnetic and Electric Fields

Gel polymer electrolytes are perspective electrolytes for new types of Li-ion batteries today. The properties respectively advantages of these gels can be used also in other fields of ...

Jahn, M.; Veselková, I.; Sedlaříková, M.; Zatloukal, M.; Bartušek, Karel
Ústav přístrojové techniky, 2018

Sixty years of the Institute os Scientific Instruments
Müllerová, Ilona
2018 - English
The Institute of Scientific Instruments (ISI) was established in 1957 as an institution providing instrumental equipment for other institutes of the Academy of Sciences, mainly in the field of electron microscopy, nuclear magnetic resonance and coherent optics. Three examples are shown in Figure 1. In the beginning the institute had only 83 employees, including the workshop which produced the electronics and all mechanical parts of the instruments. During the process of post-Communist transformation of the Academy of Sciences, which began in 1989, the development of entire instruments and devices was brought to a halt and scientific activities of our Institute focused on the methodology of probing the physical properties of matter in the above-mentioned main fields. New components of scientific instruments were developed that help push the limits of what hadpreviously been possible, continuing the long tradition of the Institute in these topics. Keywords: electron-microscopy; sem Available at various institutes of the ASCR
Sixty years of the Institute os Scientific Instruments

The Institute of Scientific Instruments (ISI) was established in 1957 as an institution providing instrumental equipment for other institutes of the Academy of Sciences, mainly in the field of ...

Müllerová, Ilona
Ústav přístrojové techniky, 2018

Photolitography on flexible substrates
Urbánek, M.; Urbánek, P.; Kuřitka, I.; Kolařík, Vladimír
2018 - English
Nowadays preparation of structures on flexible substrates is highly demanded because of using this patterns in field of flexible electronics. This contribution deals with photolitographic procces for preparation of structures on flexible substrates. The method of photolitography enables to create designed patterns in various material (e.g. metals as conductive layers) on various substrates (silicon wafers, foils, etc.). First the designed pattern is exposed through the mask by UV light into polymer resist, then the pattern is transfered into metal layer by wet etching through the developed windows in resist. In this paper several patterns are prepared through the positive resist PMMA by photolitography into various metal layer (Cu, Al) on flexible substrates. Keywords: photolithography; flexible substrates; metal layer Available at various institutes of the ASCR
Photolitography on flexible substrates

Nowadays preparation of structures on flexible substrates is highly demanded because of using this patterns in field of flexible electronics. This contribution deals with photolitographic procces for ...

Urbánek, M.; Urbánek, P.; Kuřitka, I.; Kolařík, Vladimír
Ústav přístrojové techniky, 2018

Analysis of linear ion Paul traps using 3-D FEM and the azimuthal multipole expansion
Oral, Martin; Číp, Ondřej; Slodička, L.
2018 - English
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. Keywords: linear ion traps; atomic clock; electric RF fields; simulation of electrostatic fields; finite element method; multipole field expansion; ion trajectories; particle tracing Available at various institutes of the ASCR
Analysis of linear ion Paul traps using 3-D FEM and the azimuthal multipole expansion

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 ...

Oral, Martin; Číp, Ondřej; Slodička, L.
Ústav přístrojové techniky, 2018

Orbital motion from optical spin: the extraordinary momentum of circularly polarized light beams
Svak, Vojtěch; Brzobohatý, Oto; Šiler, Martin; Jákl, Petr; Zemánek, Pavel; Simpson, Stephen Hugh
2018 - English
We provide a vivid demonstration of the mechanical effect of transverse spin momentum in an\noptical beam in free space. This component of the Poynting momentum was previously thought\nto be virtual, and unmeasurable. Here, its effect is revealed in the inertial motion of a probe\nparticle in a circularly polarized Gaussian trap, in vacuum. Transverse spin forces combine with\nthermal fluctuations to induce a striking range of non-equilibrium phenomena. With increasing\nbeam power we observe (i) growing departures from energy equipartition, (ii) the formation of\ncoherent, thermally excited orbits and, ultimately, (iii) the ejection of the particle from the trap.\nOur results complement and corroborate recent measurements of spin momentum in evanescent\nwaves, and extend them to a new geometry, in free space. In doing so, we exhibit fundamental,\ngeneric features of the mechanical interaction of circularly polarized light with matter. The work\nalso shows how observations of the under-damped motion of probe particles can provide detailed\ninformation about the nature and morphology of momentum flows in arbitrarily structured light\nfields as well as providing a test bed for elementary non-equilibrium statistical mechanics. Keywords: optical trapping; optical levitation; counter-propagating beams; optical spin Available at various institutes of the ASCR
Orbital motion from optical spin: the extraordinary momentum of circularly polarized light beams

We provide a vivid demonstration of the mechanical effect of transverse spin momentum in an\noptical beam in free space. This component of the Poynting momentum was previously thought\nto be virtual, ...

Svak, Vojtěch; Brzobohatý, Oto; Šiler, Martin; Jákl, Petr; Zemánek, Pavel; Simpson, Stephen Hugh
Ústav přístrojové techniky, 2018

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