Czech Metrology Institute

Brno, Czech Republic

Czech Metrology Institute

Brno, Czech Republic
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Kren P.,Czech Metrology Institute
Journal of the European Optical Society | Year: 2017

Background: A new algorithm for precise characterisation of rotationally symmetric aspheric surfaces by the conic section and polynomial according to the ISO 10110 standard is described. Methods: The algorithm uses only the iterative linear least squares. It uses fitting the surface form in a combination with terms containing its spatial derivatives that represent infinitesimal transformations of form. Results: The algorithm reaches sub-nanometre residuals even though the aspheric surface is translated and rotated in the space. Conclusion: he algorithm is computationally robust and an influence of local surface imperfections can be easily reduced by use of a criterion for residuals. © 2017, The Author(s).

Sluse J.,Czech Metrology Institute
EPJ Web of Conferences | Year: 2017

The article deals with influence of blockage effect caused by vane anemometer in the wind tunnel by measurement via this anemometer. The influences will be represented by correction coefficient. The first part of this article is focused on the design of the impeller of vane anemometers. The impellers are printed on 3D printer with variable parameters. The anemometer is fixed in an open section of the wind tunnel with closed loop and the velocity profile is measured by Laser Doppler velocimetry (LDV) in front and behind it for all impellers. The experimental data are compared with the numerical simulation in OpenFOAM. The results are correction coefficients. © The Authors, published by EDP Sciences, 2017.

Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: NMP.2013.1.4-2 | Award Amount: 12.85M | Year: 2013

The thermal properties of nanostructured materials are of fundamental importance to modern technology, but at present reproducible metrological definitions, tools and methods do not exist. This is because the mechanisms of heat transport at the nanoscale are entirely different to those at the macro scale. The project will place nanothermal metrology on a solid basis by an integrated physics-based experimental and modelling effort to: Define a common terminology for nanothermal measurement Realise standard materials and devices for measurement and calibration of nanothermal measurements Develop new instruments and methods for traceable nanothermal measurement Develop calibrated and validated thermal models covering the range from atomic to macro-scale Apply these tools to selected representative industrial problems Assess the tools for suitability for adoption as potential standards of measurement including their traceability and reproducibility The objectives will be achieved by a team comprising physicists, materials scientists, modellers, instrumentalists, microscopists, industrial partners (including SMEs and OEMs) and National Measurement Institutes. The outputs of QUANTIHEAT will be embodied in highly characterised reference samples, calibration systems, measurement tools, numerical modelling tools, reference measurements and documented procedures. The availability of calibrated numerical modelling tools will facilitate the rapid digital thermal design of new nanosystems without the need for extensive prototyping. Their validation against experiment over all length scales will provide a solid basis for the deployment of new nanostructured materials, devices and structures having optimised performance without the need for excessively conservative design. Standardization is a key driver of industrial and scientific progress: QUANTIHEAT is expected to constitute a de-facto standard for a key area of physical measurement at the nanoscale worldwide.

Grabner M.,Czech Metrology Institute | Kvicera V.,Czech Metrology Institute
Journal of Lightwave Technology | Year: 2014

The multiple scattering effects of light propagation in rain and fog are investigated by means of numerical Monte Carlo photon propagation simulations. Rain and fog consisting of water droplets are described by realistic drop size distributions with parameters related to physical parameters of hydrometeors such as rain intensity, liquid water content, effective droplet radius of fog and atmospheric visibility. Simulations show that optical attenuation due to rain is about two times lower than predicted by single scattering approach. Fog attenuation is also reduced for the lowest visibilities. An impulse response of optical channel in rain and fog is obtained and the explicit models for the delay spread dependence are provided. Under realistic conditions, the RMS delay spread due to rain on 1 km long free space optics (FSO) path is limited below 10 ps. Moderate and dense fog can cause the delay spread about 50 ps or more. Frequency characteristics of the FSO channel impaired by rain and fog are given. © 2013 IEEE.

Olsovcova V.,Czech Metrology Institute
Applied Radiation and Isotopes | Year: 2010

The response of radionuclide calibrators for radionuclides with high abundances of high energy X-rays is very sensitive to changes in the source geometry. The magnitude of this effect was explored for Bqmetr (Konsorcium BQM, CR) calibrators with 123I, 111In and 153Sm in several vial and syringe geometries. Dependencies of chamber responses on solution volume and container position were calculated using MCNP transport code. The possibility of usage of an additional copper filter to reduce chamber sensitivity was studied and found to be suitable. © 2009 Elsevier Ltd.

Grabner M.,Czech Metrology Institute | Kvicera V.,Czech Metrology Institute
Optics Express | Year: 2011

The wavelength dependence of the extinction coefficient in fog and haze is investigated using Mie single scattering theory. It is shown that the effective radius of drop size distribution determines the slope of the loglog dependence of the extinction on wavelengths in the interval between 0.2 and 2 microns. The relation between the atmospheric visibility and the effective radius is derived from the empirical relationship of liquid water content and extinction. Based on these results, the model of the relationship between visibility and the extinction coefficient with different effective radii for fog and for haze conditions is proposed. © 2011 Optical Society of America.

Zachovalova V.N.,Czech Metrology Institute
IEEE Transactions on Instrumentation and Measurement | Year: 2014

This paper describes mathematical modeling of cage-type ac current shunts. A calculable model was developed using lumped circuit elements. The transimpedance, ac-dc difference, and the phase angle error of a shunt can be derived from the model. An uncertainty analysis of the model was done by means of Monte Carlo methods. Comparison of the calculated and measured values shows an agreement better than 6 μΩ/Ω in the ac-dc difference and 110 μrad in the phase angle error at frequencies up to 100 kHz. © 2013 IEEE.

Kren P.,Czech Metrology Institute
Measurement Science and Technology | Year: 2014

The optical mirror is often used as a reference plane in coordinate metrology. Nevertheless, an optical system for straightness and tilting of translation stages can be replaced by a relatively cheap capacitive system. The setup with 1D scans for relative flatness measurement based on capacitive sensors is presented and compared with the absolute deflectometric method. The capacitive method is intended only for conductive targets or conductively coated optics. It can also be used for corrections or feedback in translation stages with nm precision. © 2014 IOP Publishing Ltd.

Necas D.,Masaryk University | Klapetek P.,Czech Metrology Institute | Klapetek P.,Brno University of Technology
Central European Journal of Physics | Year: 2012

In this article, we review special features of Gwyddion-a modular, multiplatform, open-source software for scanning probe microscopy data processing, which is available at http://gwyddion. net/. We describe its architecture with emphasis on modularity and easy integration of the provided algorithms into other software. Special functionalities, such as data processing from non-rectangular areas, grain and particle analysis, and metrology support are discussed as well. It is shown that on the basis of open-source software development, a fully functional software package can be created that covers the needs of a large part of the scanning probe microscopy user community. © 2011 © Versita Warsaw and Springer-Verlag Wien.

Ulvr M.,Czech Metrology Institute
19th IMEKO TC4 Symposium - Measurements of Electrical Quantities 2013 and 17th International Workshop on ADC and DAC Modelling and Testing | Year: 2013

This paper presents a calibration method with a special search coil used at the Czech Metrology Institute (CMI) for calibration of AC magnetic field meters in the range of frequencies up to 50 kHz. Special attention is given a) to the construction of magnetic flux density standards, which are used for generating the AC magnetic flux density for frequencies up to 3 kHz and for the frequency range from 3 kHz up to 50 kHz, b) to a description of special search coils used for precise measurements of the generated AC magnetic flux density, and c) to the analysis of sources of uncertainty. Calibration expanded uncertainty of (0.4 up to 0.8) % for k = 2 can be achieved by this calibration method.

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