A comparison of traceable spatial angle autocollimator calibrations performed by PTB and VTT MIKES

Autocollimators are versatile devices for angle metrology used in a wide range of applications in engineering and manufacturing. A modern electronic autocollimator generally features two measuring axes and can thus fully determine the surface normal of an optical surface relative to it in space. Until recently, however, the calibration capabilities of the national metrology institutes were limited to plane angles. Although it was possible to calibrate both measuring axes independently of each other, it was not feasible to determine their crosstalk if angular deflections were present in both axes simultaneously. To expand autocollimator calibrations from plane angles to spatial angles, PTB and VTT MIKES have created dedicated calibration devices which are based on different measurement principles and accomplish the task of measurand traceability in different ways. Comparing calibrations of a transfer standard makes it possible to detect systematic measurement errors of the two devices and to evaluate the validity of their uncertainty budgets. The importance of measurand traceability via calibration for a broad spectrum of autocollimator applications is one of the motivating factors behind the creation of both devices and for this comparison of the calibration capabilities of the two national metrology institutes. The latter is the focus of the work presented here.

Calibration procedures for torque measuring devices by using a reference type torque calibration machine at NMIJ

NMIJ / AIST has been disseminating the national torque standard to Japanese industry by using deadweight type torque standard machines (DWTSMs). In general, DWTSMs can generate more precise torque than other types of TSMs. On the other hand, the calibration takes much longer time than others. One possible solution is to use a reference type torque calibration machine (RTCM). RTCMs have been developed in some national metrology institutes (NMIs). We have started the development of the first RTCM in the range of 100 mN · m to 10 N · m. In this study, we developed the automatic calibration system of the RTCM and investigated the calibration procedures for a low nominal capacity torque measuring device (TMD). It was found that the calibration could be realised by the RTCM, compared with the reliable DWTSM of rated capacity of 10 N · m at NMIJ.

Metrology for Climate Sciences: The European Metrology Network for Climate and Ocean Observation

<div> <p>Environmental observations of essential climate variables (ECVs) and related quantities made by satellites and in situ observational networks are used for a wide range of societal applications. To identify a small climate trend from an observational record that is also sensitive to changes in weather, to seasonal effects and to geophysical processes, it is essential that observations have a stable basis that holds for multiple decades, whilst still allowing for changes in the observation instrumentation and operational procedures. To achieve this, all aspects of data collection and handling must be underpinned by robust quality assurance. The resultant data should also be linked to a common reference, with well-understood uncertainty analysis, so that observations are interoperable and coherent; in other words, measurements by different organisations, different instruments and different techniques should be able to be meaningfully combined and compared.    </p> </div><div> <p>Metrology, the science of measurement, can provide a critical role in enabling robust, interoperable and stable observational records and can aid users in judging the fitness-for-purpose of such records. In addition to Global Climate Observing System (GCOS) monitoring principles, metrology’s value, and the role of National Metrology Institutes (NMI) in observations, has been recognised in initiatives such as the Quality Assurance Framework for Earth Observation (QA4EO) established by the Committee on Earth Observation Satellites (CEOS) and in the implementation plans of the World Meteorological Organization’s (WMO’s), Global Atmosphere Watch and the European Ocean Observing System.  </p> </div><div> <p>The European Association for National Metrology Institutes (EURAMET) has recently created the “European Metrology Network (EMN) for Climate and Ocean Observation” to support further engagement of the expert communities with metrologists at national metrology insitutes and to encourage Europe’s metrologists to coordinate their research in response to community needs. The EMN has a scope that covers metrological support for in situ and remote sensing observations of atmosphere, land and ocean ECVs (and related parameters) for climate applications. It also covers the additional economic and ecological applications of ocean Essential Ocean Variable (EOV) observations. It is the European contribution to a global effort to further enhance metrological best practice into such observations through targeted research efforts.  </p> </div><div> <p>In late 2019 and early 2020 the EMN carried out a survey to identify the need for metrology within the observational communities and held a webinar workshop to prioritise the identified needs. Here we present the results of the survey and discuss the role that metrology can play in the climate observing system of the future. </p> </div>

BIPM and IUPAC formalize a long-standing cooperation

IUPAC has signed a Memorandum of Understanding with the Bureau International des Poids et Mesures (BIPM). Signed on 17 October 2019 at the BIPM during the meeting of the National Metrology Institutes (NMI) Directors, the MoU formalizes the long-standing cooperation between the BIPM and IUPAC.

Assessment of Equivalence of the Spectral Radiance Scales following the results of the comparison between the National Metrology Institutes of Korea, China, and Russia

The paper presents the assessment of equivalence of the spectral radiance scales in the wavelength range from 250 nm to 2500 nm, reproduced at the national metrology institutes of Korea (KRISS), China (NIM) and Russia (VNIIOFI), carried out in the framework of international comparison. The common set of three tungsten strip lamps was used as an artefact. Based on a series of blind measurements of the lamps spectral radiance performed at each laboratory, the reference value of the comparison was determined at each wavelength as a weighted mean of the measured data of three laboratories. The degree of equivalence of each laboratory was then calculated as the deviation of the measurement data of that participant from the reference value. A data analysis method was proposed for calculating the degree of equivalences and their uncertainties. The method is based on processing spectral radiance ratios, rather than differences, which allows eliminating the influence of a result of one particular participant to results of other laboratories. The comparison results confirm the equivalence of spectral radiance scales of all the laboratories within their expanded uncertainties except a few wavelength points.