Czech Metrology Institute Research Articles

Optical characterisation of three reference Dobsons in the ATMOZ Project – verification of G. M. B. Dobson's original specifications

Abstract. Three reference Dobsons (regional standard Dobsons No. 064, Germany and No. 074, Czech Republic as well as the world standard No. 083, USA) were optically characterized at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig in 2015 and at the Czech Metrology Institute (CMI) in Prague in 2016 within the EMRP ENV 059 project “Traceability for atmospheric total column ozone”. Slit functions and the related parameters of the instruments were measured and compared with G. M. B. Dobson's specifications in his handbook. All Dobsons show a predominantly good match of the slit functions and the peak (centroid) wavelengths with deviations between −0.11 and +0.12 nm and differences of the full width half maximum (FWHM) between 0.13 and 0.37 nm compared to the nominal values at the shorter wavelengths. Slightly larger deviations of the FWHMs from the nominal Dobson data, up to 1.22 nm, can be seen at the longer wavelengths, especially for the slit function of the long D-wavelength. However, differences between the effective absorption coefficients (EACs) for ozone derived using Dobson's nominal values of the optical parameters on one hand and these measured values on the other hand are not too large in the case of both “old” Bass–Paur (BP) and “new” IUP-ozone (Institut für Umweltphysik, University of Bremen) absorption cross sections. Their inclusion in the calculation of the total ozone column (TOC) leads to improvements of significantly less than ±1 % at the AD-wavelengths between −1 and −2 % at the CD-wavelengths pairs in the BP-scale. The effect on the TOC in the IUP-scale is somewhat larger at the AD-wavelengths, up to +1 % (D074), and smaller at the CD-wavelengths pair, from −0.44 to −1.5 %. Beside this positive effect gained from the data with higher metrological quality that is needed for trend analyses and satellite validation, it will be also possible to explain uncommon behaviours of field Dobsons during calibration services, especially when a newly developed transportable device TuPS (tuneable portable radiation source) from CMI proves its capability to provide similar results as the stationary setups in the laboratories of National Metrology Institutes. Then, the field Dobsons can be optically characterized as well during regular calibration campaigns. A corresponding publication will be prepared using the results of TuPS-based measurements of more than 10 Dobsons in field campaigns in 2017.

Improvements to the NMR Method With Flowing Water at CMI

Nuclear magnetic resonance (NMR) is a very important technique for making accurate measurements of the magnetic flux density B of dc magnetic fields in a wide range of values. This paper presents improvements to the NMR method with flowing water (the nutation method). The method is used at the Czech Metrology Institute and provides an improved signal-to-noise ratio of the amplitude of the NMR signal, new resonance frequency value by searching nutation double pattern recording, and an improved calibration uncertainty value. This method is used for calibration of the coil standards of magnetic flux density with a constant value below 20 mT/A. Using the improved nutation method presented here, the magnetic flux density coil standard can be calibrated within a period of less than 30 min in the range of 0.1 to 100 mT with expanded uncertainty of 20 to 60 ppm.

SUPPLEMENTARY COMPARISON COOMET. M.P-S5 of hydraulic gauge pressure standards from 5 MPa to 34 MPa

This report describes the results of bilateral inter laboratory comparison (BILC) denoted as COOMET.M.P-S5 (also known as supplementary comparison COOMET 723/AZ/17). The comparison measurements between the two participants, Czech Metrology Institute (CMI) (pilot laboratory) and Azerbaijan İnstitute of Metrology (AzMI), started in April 2017 and finished in June 2017. The transfer standards was a digital manometer, Crystal XP 2i with the gauge pressure range (0–34000) kPa.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

System for automatic gauge block length measurement optimized for secondary length metrology

This paper presents a contactless system for automatic gauge blocks calibration based on combination of laser interferometry and low-coherence interferometry. In the presented system, the contactless measurement of the absolute gauge block length is done as a single-step operation without any change in optical setup during the measurement. The optical setup is combined with compact gauge block changer with a capacity of 126-ga blocks, which makes the resulting system fully automatic.The paper also presents in detail a set of optimization steps which have been done in order to transform the original experimental setup into the automatic system which meets secondary length metrology requirements. To prove the measurement traceability, we conducted a set of gauge block length measurement comparing data from the optimized system and the established reference systems TESA NPL A.G.I. 300 and TESA–UPC operated in Czech Metrology Institute Laboratory.

An impedance bridge measuring the capacitance ratio in the high frequency range up to 1 MHz

This paper describes a 2-terminal-pair impedance bridge, measuring the capacitance ratio in the high frequency range up to 1 MHz. The bridge was configured with two voltage sources and a phase control unit which enabled the bridge balance by synchronizing the voltage sources with an enhanced phase resolution. Without employing the transformers such as inductive voltage divider, injection and detection transformers, etc, the bridge system is quite simple to set up, and the balance procedure is quick and easy. Using this dual-source coaxial bridge, the 1:1 and 10:1 capacitance ratios were measured with 1 pF–1 nF capacitors in the frequency range from 1 kHz to 1 MHz. The measurement values obtained by the dual-source bridge were then compared with reference values measured using a commercial precision capacitance bridge of AH2700A, the Z-matrix method developed by ourselves, and the 4-terminal-pair coaxial bridge by the Czech Metrological Institute. All the measurements agreed within the reference uncertainty range of an order of 10−6–10−5, proving the bridge ability as a trustworthy tool for measuring the capacitance ratio in the high frequency range.

On-site comparison of Quantum Hall Effect resistance standards of the CMI and the BIPM: ongoing key comparison BIPM.EM-K12

An on-site comparison of the quantum Hall effect (QHE) resistance standards of the Czech Metrology Institute (CMI) and of the Bureau International des Poids et Mesures (BIPM) was made in April 2017. Measurements of a 100 Ω standard in terms of the conventional value of the von Klitzing constant, R K-90, agreed to 6 parts in 1010 with a relative combined standard uncertainty u c = 25 × 10−10. Measurements of 10000 Ω/100 Ω and 100 Ω/1 Ω ratios agreed to 11 parts in 1010 with u c = 22 × 10−10 and to 33 parts in 1010 with u c = 32 × 10−10, respectively. The influence of the current reversal time has been systematically investigated in order to take into account possible errors due to the Peltier effect, which may be particularly large in 1 Ω standards.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on the key comparison CCM.P-K4.2012 in absolute pressure from 1 Pa to 10 kPa

The report summarizes the Consultative Committee for Mass (CCM) key comparison CCM.P-K4.2012 for absolute pressure spanning the range of 1 Pa to 10 000 Pa. The comparison was carried out at six National Metrology Institutes (NMIs), including National Institute of Standards and Technology (NIST), Physikalisch-Technische Bundesanstalt (PTB), Czech Metrology Institute (CMI), National Metrology Institute of Japan (NMIJ), Centro Nacional de Metrología (CENAM), and DI Mendeleyev Institute for Metrology (VNIIM). The comparison was made via a calibrated transfer standard measured at each of the NMIs facilities using their laboratory standard during the period May 2012 to September 2013. The transfer package constructed for this comparison preformed as designed and provided a stable artifact to compare laboratory standards. Overall the participants were found to be statistically equivalent to the key comparison reference value.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Doping‐Induced Absorption Bands in P3HT: Polarons and Bipolarons

AbstractThe front cover artwork is provided by Dr. Christina Enengl, Dr. Sandra Enengl and Dr. Helmut Neugebauer (Johannes Kepler University, Austria), Dr. Marek Havlicek (Czech Metrology Institute, Czech Republic; Johannes Kepler University, Austria), Sandra Pluczyk and Prof. Mieczyslaw Lapkowski (Silesian University of Technology, Poland) as well as Prof. Eitan Ehrenfreund (Technion‐Israel Institute of Technology, Israel). The image illustrates the formation of bipolarons in P3HT at higher doping levels observed by in situ spectroscopic techniques. Read the full text of the article at 10.1002/cphc.201600961.

Gauge Block Calibration by Interferometry

Absolute length calibration of gauge blocks traceable to the definition of meter is an important task of the national metrology institutes responsible for providing reliable length artifacts for industrial use. The length of a gauge block (henceforth, represented as GB) is defined in ISO 3650 as the distance between its one measuring face and the surface of an auxiliary platen on which the other measuring face has been wrung. Accordingly, in central length calibration of K-grade GBs using interferometry, it is required that they be wrung onto an auxiliary platen whose characteristics are the same as the measuring face of the GBs. According to this definition, the length of a GB consists of its mechanical length between two faces and the wringing film thickness. This definition is practical and reasonable in many cases because GBs are used as length standards with wringing. Also this calibration method has the advantage that the thickness of the wringing film is propagated appropriately when lower grade GBs are calibrated by comparison to higher grade GBs via a mechanical comparator. In terms of this paper is briefly described interferometry method of gauge blocks calibration. The paper was written in conjunction with Czech Metrology Institute.

Measurement of the 86Rb decay data

A radionuclide solution of 86Rb was standardised by the absolute measurement method 4πβ-γ coincidence counting at the Czech Metrology Institute. The created sources were measured by two calibrated HPGe γ spectrometers in order to estimate the γ-emission intensity, energy of the γ-emission and half-life of the 86Rb. The aim of this work was to improve and spread the currently published values. An intensity value of 8.74 (7) % was achieved for the obtained 1076.772 (75) keV γ-emission. We also determined the half-life 18.684 (9) d of the 86Rb. The obtained energy of the γ-emission and the γ-emission intensity are in a good agreement with the results obtained in recent experiments. The half-life found is in a rather good agreement with previously reported values.

Comparisons organized by Ionizing Radiation Metrology Laboratory of FTMC, Lithuania

The newly established Ionizing Radiation Metrology Laboratory of the National Metrology Institute (FTMC) in Lithuania organized four comparisons in the field of low-level radioactivity measurements in water. For gamma-ray emitters, the activity concentration in the samples was in the range 1–25Bq/kg, while for tritium it was around 2Bq/g. The assigned values of all comparisons were traceable to the primary standards of the Czech Metrology Institute (CMI).

Energy dependence of Fricke-xylenol orange gel and gel based on Turnbull blue for low-energy photons

The paper describes the energy dependence of two types of radiochromic gels, a Fricke-xylenol orange gel (FX gel) and a gel based on Turnbull blue (TB gel), on low energy photons between 14 and 145 keV. Gel samples were irradiated at reference photon fields at the Czech Metrology Institute and evaluated by two independent optical methods. Measurements revealed that the response of the TB gel is independent on photon energy down to at least 14 keV photons, while the FX gel is energy dependent for photons below roughly 50 keV.

Results and evaluation of key comparison CCM.P-K12.1 for very low helium flow rates (leak rates)

The Czech Metrology Institute (CMI) took part and failed to prove equivalence in the Key Comparison CCM.P-K12 of helium leak artefacts (leak rates) into vacuum. After identifying and eliminating the cause of the failure, the Institute of Metals and Technology (IMT) of Slovenia, a successful participant in CCM.P-K12, volunteered to serve as pilot and link in a following bilateral comparison of IMT and CMI that obtained designation CCM.P-K12.1 in June 2012. It was decided to perform the comparison with a glass permeation helium leak artefact at nominally 3·10-11 mol/s (7.4·10-7 mbar·L·s-1) at 23 °C. Both the laboratory standards took part in CCM.P-K12 and were considered as primary. The comparison measurements were performed in October 2012. CMI proved equivalence both with IMT and with the reference value of the key comparison CCM.P-K12.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Calibration of a Measuring Device to Determine Specific Saturation Magnetization by A Special Coil

Abstract Specific saturation magnetization σ S is an important parameter of ferromagnetic materials. It is in principle independent of the structure and shape of the sample. There are two ways to calibrate devices for determining σ S : the standard method, using a calibrated magnetic moment standard, or an alternative method, using a special moment coil. This paper presents a calibration method used at Czech Metrology Institute for calibration of Koerzimat 1.096 using a special moment coil. Special attention is given to a description of the special moment coils used for Koerzimat 1.096 calibration, and to analysis of sources of uncertainty. Calibration expanded uncertainty of 0.4 up to 0.6 % can be achieved using this method.

Characterization of the new free-air primary standard for low-energy X-rays at CMI

In 2011 a decision was made by Czech Metrology Institute to build a free-air ionization chamber (FAC) intended to be used as a primary standard of air kerma rate for low-energy X-rays (photon energy below 50 keV, including mammography X-ray qualities) in order to replace the currently used secondary ionization chamber and to decrease the uncertainty of air kerma reference value. In the period 2011–2012, the FAC has been designed, manufactured and put into operation. Its performance was tested using a calibrated secondary chamber and then by an informal comparison with a national primary standard of BEV (Austria). Physical characteristics of the FAC are described and individual correction factors are discussed focusing on computational methods utilized in their estimation. Summary of the correction factors with the uncertainty budget is presented. • A new primary standard for low-energy X-ray beam constructed at CMI. • Correction factors calculated by MCNPX simulations. • The chamber performance tested by an informal comparison with BEV (Austria). • The chamber considered ready for key comparison and standardization of X-ray beams.

Short-Range Six-Axis Interferometer Controlled Positioning for Scanning Probe Microscopy

We present a design of a nanometrology measuring setup which is a part of the national standard instrumentation for nanometrology operated by the Czech Metrology Institute (CMI) in Brno, Czech Republic. The system employs a full six-axis interferometric position measurement of the sample holder consisting of six independent interferometers. Here we report on description of alignment issues and accurate adjustment of orthogonality of the measuring axes. Consequently, suppression of cosine errors and reduction of sensitivity to Abbe offset is achieved through full control in all six degrees of freedom. Due to the geometric configuration including a wide basis of the two units measuring in y-direction and the three measuring in z-direction the angle resolution of the whole setup is minimize to tens of nanoradians. Moreover, the servo-control of all six degrees of freedom allows to keep guidance errors below 100 nrad. This small range system is based on a commercial nanopositioning stage driven by piezoelectric transducers with the range (200 × 200 × 10) μm. Thermally compensated miniature interferometric units with fiber-optic light delivery and integrated homodyne detection system were developed especially for this system and serve as sensors for othogonality alignment.

Final report on EUROMET supplementary comparison of 500 kg standard (EUROMET.M.M-S1)

This report describes the results of the international comparison EUROMET.M.M-S1 (also known as EUROMET Project No. 461) between 15 participants. The comparison started in June 2001 and finished in July 2003.The Czech Metrology Institute was the pilot laboratory of the project. The transfer standard with nominal mass of 500 kg was provided by Raute Precision (Finland). Agreement between all participants is good except for one laboratory. The result of this laboratory was stated as an outlier and was not used in calculating the reference value.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on EUROMET PR-K2.b: Comparison on spectral responsivity (300 nm to 1000 nm)

This report contains the results of the regional comparison EUROMET PR-K2.b (registered in the KCDB under the identifier EURAMET.PR-K2.b). Ten laboratories took part in it, including the pilot. In general the results are consistent, with a few exceptions as explained in the report.The comparison gives international linkage in spectral responsivity from 300 nm to 1000 nm to seven European laboratories: Bundesamt für Metrologie und Akkreditierung (METAS), Norwegian Metrology and Accreditation Service (Justervesenet), Central Office of Measures (GUM), National Institute of Metrology (INM-Romania), Optics Laboratory of TUBITAK-UME (UME), Czech Metrology Institute (CMI) and Swedish National Testing and Research Institute (SP). Three laboratories provided the link to CCPR-K2.b: Bureau National de Metrologie (BNM-INM/CNAM), Instituto de Optica 'Daza de Valdés' (IO-CSIC, acting as pilot) and NMi Van Swinden Laboratorium BV (NMi-VSL).Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on EURAMET.T-K7.1: Bilateral key comparison of water triple point cells

This is the final report of key comparison EURAMET.T-K7.1, a bilateral comparison of water triple point cells between the Czech Metrology Institute, CMI, and the Slovensky Metrologicky Ustav, SMU, of Slovakia. The comparison was requested by CMI, and the measurement protocol was compatible with the one used for key comparison EUROMET.T-K7. The results show a satisfactory degree of equivalence between SMU and CMI, and allow linkage to the parent key comparison EUROMET.T-K7. As a consequence, CMI is able to support CMCs at the temperature of the triple point of water and submit them for publication in the KCDB.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison of the Josephson voltage standards of the CMI and the BIPM (part of the ongoing BIPM key comparison BIPM.EM-K10.b)

A comparison of the 10 V Josephson array voltage standard of the Bureau International des Poids et Mesures (BIPM) was made with that of the Czech Metrology Institute (CMI), Czech Republic, in February 2011. For this exercise, option B of the comparison protocol was applied for the nominal voltage of 10 V. The BIPM provided a reference voltage for measurement by the CMI using its Josephson standard with its own measuring device (option B of the comparison protocol). The final results are in good agreement within the combined relative standard uncertainty of 10.3 parts in 1010 for the nominal voltage of 10 V.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).