Ústav přístrojové techniky

Nejnovější přírůstky:
2017-10-04
17:58
Effect of thermal radiation on low temperature measurement for various types of temperature sensor installations
Urban, Pavel ; Hanzelka, Pavel ; Králík, Tomáš ; Vlček, Ivan ; Srnka, Aleš
We investigated an effect of thermal radiation (300 K) on precision of low temperature measurement of a sample holder (or sample) in an UHV SEM/SPM microscope working at range down to 20 K for various ways of temperature sensor mounting. We designed a special copper casing for installation of Lake Shore\ntemperature sensors (CernoxTM and Si diodes) encapsulated in SD packages. The sensor body is attached direct to the casing using indium solder. The current leads pertaining to the sensor are thermally anchored but electrically insulated from the casing. Quality of sensors installation in the casing was tested for various ways of mounting on a cooled plate. Insufficient thermal anchoring of electrical wires and thermal shielding were imitated. Comparative measurement was also performed with sensors in SD package mounted without\ncasing. The experiments proved that our special design of temperature sensors casing is adequate for intended application of temperature measurement of sample holder in UHV SEM/SPM microscope. In contrary, measurement precision of unprotected sensors was absolutely unsuitable.

Úplný záznam
2017-10-04
17:58
Role of the superconductivity in radiative heat transfer
Králík, Tomáš ; Musilová, Věra ; Srnka, Aleš ; Fořt, Tomáš ; Frolec, Jiří
The absorption and emission of thermal radiation by metals is related to their electrical properties that are influenced by impurities, defects and temperature. We show by some examples of measurements on common metals how different can be the thermal radiative properties. When the heat is transferred across a microscopic vacuum gap in the near field regime, it is possible to achieve a step-like change of the heat\ntransfer based on a superconducting transition. An interesting feature of this effect is the nonlinear thermal conductivity effecting a change of the sign of the differential thermal conductivity across the vacuum gap.

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2017-10-04
17:58
Effect of gold coating on emissivity and absorptivity of Ti-6Al-4V alloy
Frolec, Jiří ; Králík, Tomáš ; Musilová, Věra ; Urban, Pavel
The article provides experimental analysis of total hemispherical emissivity and absorptivity of Ti-6Al-4V alloy before and after deposition of 1-2 .pí.m gold layer. We measured their dependences on the temperature of thermal radiation (varying from 20 K to 320 K) and confronted these results with mechanically polished copper, i.e. with material known for extremely low emissivity and absorptivity. Galvanic deposition of pure gold resulted in significant lowering of original emissivity of Ti-6Al-4V bare surfaces from 15.8 percent to 3.4 percent at 300 K and from 4.1 percent to 1.1 percent at 20 K. Our findings about thermal-radiative properties have practical relevance for an improvement of a low temperature part of an ultra-high vacuum scanning probe microscope\n(UHV-SPM) designed by our group and could also be useful for other applications and low temperature systems.

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2017-04-04
15:25
Blaze Gratings with a Ribbed Back Slope
Krátký, Stanislav ; Meluzín, Petr ; Horáček, Miroslav ; Kolařík, Vladimír ; Matějka, Milan ; Chlumská, Jana ; Král, Stanislav
Binary relief phase-modulated gratings provide symmetrical diffraction of the incoming light beam. Asymmetrical gratings, e.g. asymmetrical triangular blazed gratings, are characteristic by an asymmetrical diffraction behavior, where one of the first diffraction orders is more important than the other one. Electron beam lithography is a suitable and flexible tool for patterning of such kind of gratings. High quality results can be readily obtained when the period of the grating is relatively large and the relief depth is relatively low, this is the case of gratings with a small blaze angle. As the blaze angle increases, the quality of result suffers from several patterning-related issues. One of the problems is a reflection of the incoming light beam from the back slope (anti-blaze facet) of the blaze grating. We propose a novel configuration, with a ribbed modulation of the back slope. This modulation is perpendicular to the direction of the grating grooves. This paper presents an analysis of the proposed blazed grating configuration. E-beam pattern generators were used to prepare a few\nsamples of blaze gratings with a ribbed back slope. One part of the experiment was performed with a Gaussianshaped beam and another one with the variable-shaped beam. Results of the experiment are presented.\nFinally, we discuss the optical performance of two blaze gratings with similar parameters, one of them is with the flat back slope and another one is with the ribbed back slope.

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2017-04-04
15:25
Parameter Optimization of Multi-Level Diffraction Gratings
Matějka, Milan ; Kolařík, Vladimír ; Horáček, Miroslav ; Král, Stanislav
Originally, the e-beam lithography (EBL) is a technique for creating high-resolution black and white masks for the optical lithography. Multi-level relief structures can be also prepared using EBL patterning. Their preparation is based on the image patterning with a gradient of exposure doses. Large-area multi-level structures can be effectively prepared using the electron beam pattern generator with a variable shaped beam. We present several writing strategies. Basically, the main writing strategy uses one stamp (i.e. one elementary exposure of the shaped electron beam) per one elementary area with the same exposure dose. This simple approach is fast and flexible, however it does not guarantee optimal results. The main problem is an imperfection of the stamps (size, shape, and homogeneity). Advanced algorithms are based on multiple\nexposure of the same elementary area, the total local exposure dose is a sum of several different elementary exposures (stamps). Using these algorithms, a smoother surface of the structure can be achieved. On the other hand, the writing speed is considerably decreased. Tradeoff between the achieved parameters and the writing speed is discussed for selected set of writing strategy algorithms.

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2017-04-04
15:25
Nanopatterning of Silicon Nitride Membranes
Matějka, Milan ; Krátký, Stanislav ; Řiháček, Tomáš ; Kolařík, Vladimír ; Chlumská, Jana ; Urbánek, Michal
Membranes are typically created by a thin silicon nitride (SIN) layer deposited on a silicon wafer. Both, top and bottom side of the wafer is covered by a thin layer of the silicon nitride. The principle of silicon nitride membranes preparation is based on the wet anisotropic etching of the bottom side of the silicon wafer with crystallographic orientation (100). While the basic procedure for the preparation of such membranes is well known, the nano patterning of thin membranes presents quite important challenges. This is partially due to the mechanical stress which is typically presented within such membranes. The resolution requirements of the\nmembrane patterning have gradually increased. Advanced lithographic techniques and etching procedures had to be developed. This paper summarizes theoretical aspects, technological issues and achieved results. The application potential of silicon nitride membranes as a base for multifunctional micro system (MMS) is also\ndiscussed.

Úplný záznam
2017-04-04
15:25
Structural Colors of Self-Similar Nano Patterns
Meluzín, Petr ; Horáček, Miroslav ; Krátký, Stanislav ; Kolařík, Vladimír
E-beam lithography is a flexible technology for various diffraction gratings origination. The e-beam patterning typically allows for the creation of optical diffraction gratings in the first diffraction order. However, the very high resolution enables also the patterning of structures providing the zero-order diffraction. Recently, we presented a work on the structural colors of metallic layers covering both regular-line structures and CGH (computer generated hologram) structures. This work presents a study dealing with zero-order diffraction structures with self-similar properties. The practical part of the work is focused on two aspects: design parameters and technological issues. Variations in design parameters include the tone of the structure (positive or negative),\nthe density of filling, the filling factor, and the depth of the structures. The achieved gamut of colors may by primarily extended by the proper selection of metal deposition technology and its parameters, and further by the proper selection of the metal and the thickness of its layer; these are the technological issues.

Úplný záznam
2017-04-04
15:25
Phyllotactic Model Linking Nano and Macro World
Horáček, Miroslav ; Meluzín, Petr ; Krátký, Stanislav ; Urbánek, Michal ; Bok, Jan ; Kolařík, Vladimír
Recently, the arrangement of diffraction primitives according to a phyllotactic model was presented. This arrangement was used to benchmarking purposes of the e-beam writer nano patterning. The phyllotactic arrangement has several interesting properties. One of them is related with the coherence between the nanoor microscopic domain of individual optical primitives and the properties of visually perceived images crated by these structures in the macro domain. This paper presents theoretical analysis of the phyllotactic arrangement in the referred context. Different approaches enabling the creation of diffractive optically variable images are proposed. The practical part of the presented work deals with the nano patterning of such structures using two different types of the e-beam pattern generators. One of them is a system with a variable shaped beam of electrons, while the other one is a system with a Gaussian-shaped beam. E-beam writing strategies and the use of inherent spiral patterns for exposure ordering and partitioning are also discussed.

Úplný záznam
2017-03-17
18:38
Sborník příspěvků multioborové konference LASER56
Růžička, Bohdan
Konference LASER 56 je mezioborová a intersektorová akce, na které se mohou potkat profesionálové z různých oborů. Společným jmenovatelem jsou lasery, optika a jejich aplikace. Účastníci pocházejí z různých prostředí (soukromé společnosti, vysoké školy, veřejné výzkumné organizace atd.).\n\n

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2017-03-17
18:38
Measurement of Concentration of Air Ions in the Cisarska Cave
Roubal, Z. ; Szabó, Z. ; Bartušek, Karel ; Steinbauer, M.
It was confirmed that the concentration of light air ions has a positive influence on human health. In the Cisarska Cave is sanatorium for treatment of asthma. For analyse this cave was performed measurement of concentration of light negative ions. Using grounding was reduced measurement uncertainty.

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