The calibration of Pt/Rh thermocouples up to 1560 \(^{\circ }\hbox {C}\) at NMIA currently uses the conventional ‘melt-wire technique’ to realize Gold (Au) and Palladium (Pd) melting points, resulting in the loss of 20 mm of wire from the junction end for each calibration. To avoid this loss, NMIA intends to replace the melt-wire technique with the use of miniature fixed-point cells. NMIA has established Copper (Cu) and Cobalt–Carbon (Co–C) eutectic cells for calibration of thermocouples to 1324 \(^{\circ }\hbox {C}\). To extend the calibration up to 1500 \(^{\circ }\hbox {C}\), miniature Palladium–Carbon (Pd–C) eutectic cells (1492 \(^{\circ }\hbox {C}\)) have been constructed and tested in collaboration with NMIJ, AIST. Although these cells are made of high-purity reference materials, careful consideration must be given to contamination introduced during the manufacture and filling of the crucibles and by their long-term use. These issues can only be assessed by measurement of cell-to-cell temperature differences within the ensemble of cells traceable to ITS-90. In the work presented here, 3 NMIA-design mini Pd–C cells were constructed: 1 at NMIA and 2 at NMIJ. These cells were compared, together with a “large” NMIJ Pd–C cell, using type-R, type-B and Pt/Pd thermocouples and radiation thermometry. Although the cells are found to be stable and repeatable, significant problems arising from migration of Pd to the thermocouples were identified.

Heat-flux sensors are widely used in industry to test building products and designs for resistance to bushfire, to test the flammability of textiles and in numerous applications such as concentrated solar collectors. In Australia, such detectors are currently calibrated by the National Measurement Institute Australia (NMIA) at low flux levels of 20 W · m ^-2 . Estimates of the uncertainty arising from nonlinearity at industrial levels (e.g. 50 kW · m ^-2 for bushfire testing) rely on literature information. NMIA has developed a facility to characterize the linearity response of these heat-flux sensors up to 110 kW · m ^-2 using a low-power CO_2 laser and a chopped quartz tungsten–halogen lamp. The facility was validated by comparison with the conventional flux-addition method, and used to characterize several Schmidt–Boelter-type sensors. A significant nonlinear response was found, ranging from ( 3.2 ± 0.9 )

The eutectic alloys rhenium-carbon, platinum-carbon and cobalt-carbon have been proposed as reference standards for thermometry, with temperature and uncertainty values specified within the mise en pratique of the definition of the kelvin. These alloys have been investigated in a collaboration of eleven national measurement institutes and laboratories. Published results reported the point-of-inflection in the melting curve with extremely low uncertainties. However, to be considered as standards it is necessary to stipulate what phenomenon a temperature value has been ascribed to; specifically, this should be a thermodynamic state. Therefore, the data have been further evaluated and the equilibrium liquidus temperatures determined based on a consideration of limits and assuming a rectangular probability distribution. The values are: for rhenium-carbon 2747.91 +/- 0.44 K, for platinum-carbon 2011.50 +/- 0.22 K and for cobalt-carbon 1597.48 +/- 0.14 K, with uncertainties at approximately a 95% coverage probability. It is proposed that these values could be used as the basis of thermodynamic temperature measurement at high temperatures (above 1300 K).

Heat-flux sensors are widely used in industry to test building products and designs for resistance to bushfire, to test the flammability of textiles and in numerous applications such as concentrated solar collectors. In Australia, such detectors are currently calibrated by the National Measurement Institute Australia (NMIA) at low flux levels of 20 W \(\cdot \) m\(^{-2}\). Estimates of the uncertainty arising from nonlinearity at industrial levels (e.g. 50 kW \(\cdot \) m\(^{-2}\) for bushfire testing) rely on literature information. NMIA has developed a facility to characterize the linearity response of these heat-flux sensors up to 110 kW \(\cdot \) m\(^{-2}\) using a low-power \(\hbox {CO}_2\) laser and a chopped quartz tungsten–halogen lamp. The facility was validated by comparison with the conventional flux-addition method, and used to characterize several Schmidt–Boelter-type sensors. A significant nonlinear response was found, ranging from (\(3.2 \pm 0.9\))% at 40 kW \(\cdot \) m\(^{-2}\) to more than 8 % at 100 kW \(\cdot \) m\(^{-2}\). Additional measurements confirm that this is not attributable to convection effects, but due to the temperature dependence of the sensor’s responsivity.

The thermodynamic temperature of the point of inflection of the melting transition of Re-C, Pt-C and Co-C eutectics has been determined to be 2747.84 ± 0.35 K, 2011.43 ± 0.18 K and 1597.39 ± 0.13 K, respectively, and the thermodynamic temperature of the freezing transition of Cu has been determined to be 1357.80 ± 0.08 K, where the ± symbol represents 95% coverage. These results are the best consensus estimates obtained from measurements made using various spectroradiometric primary thermometry techniques by nine different national metrology institutes. The good agreement between the institutes suggests that spectroradiometric thermometry techniques are sufficiently mature (at least in those institutes) to allow the direct realization of thermodynamic temperature above 1234 K (rather than the use of a temperature scale) and that metal-carbon eutectics can be used as high-temperature fixed points for thermodynamic temperature dissemination. The results directly support the developing mise en pratique for the definition of the kelvin to include direct measurement of thermodynamic temperature.

A new laser-based technique to examine heat transfer and energetics of phase transitions in metal–carbon fixed points and potentially to improve the quality of phase transitions in furnaces with poor uniformity is reported. Being reproducible below 0.1 K, metal–carbon fixed points are increasingly used as reference standards for the calibration of thermocouples and radiation thermometers. At NMIA, the Co–C eutectic point is used for the calibration of thermocouples, with the fixed point traceable to the International Temperature Scale (ITS-90) using radiation thermometry. For thermocouple use, these cells are deep inside a high-uniformity furnace, easily obtaining excellent melting plateaus. However, when used with radiation thermometers, the essential large viewing cone to the crucible restricts the furnace depth and introduces large heat losses from the front furnace zone, affecting the quality of the phase transition. Short \(\hbox {CO}_{2}\) laser bursts have been used to illuminate the cavity of a conventional Co–C fixed-point cell during various points in its melting phase transition. The laser is employed to partially melt the metal at the rear of the crucible providing a liquid–solid interface close to the region being observed by the reference pyrometer. As the laser power is known, a quantitative estimate of \((166 \pm 30) \hbox { J}{\cdot }\hbox {g}^{-1}\) can be made for the Co–C latent heat of fusion. Using a single laser pulse during a furnace-induced melt, a plateau up to 8 min is observed before the crucible resumes a characteristic conventional melt curve. Although this plateau is satisfyingly flat, well within 100 mK, it is observed that the plateau is laser energy dependent and elevates from the conventional melt “inflection-point” value.

The development and performance of a handheld emissometer for the measurement of the emissivity of highly reflective metallic foils used for the insulation of domestic and commercial buildings are described. Reflective roofing insulation based on a thin coating of metal on a more robust substrate is very widely used in hotter climates to reduce the radiant heat transfer between the ceiling and roof in commercial and residential buildings. The required normal emissivity of these foils is generally below 0.05, so stray reflected ambient infrared radiation (IR) makes traditional reflectance-based measurements of emissivity very difficult to achieve with the required accuracy. Many manufacturers apply additional coatings onto the metallic foil to reduce visible glare during installation on a roof, and to provide protection to the thin reflective layer; however, this layer can also substantially increase the IR emissivity. The system as developed at the National Measurement Institute, Australia (NMIA) is based on the principle of measurement of the modulation in thermal infrared radiation, as the sample is thermally modulated by hot and cold air streams. A commercial infrared \(8\,\upmu \hbox {m}\) to \(14\,\upmu \hbox {m}\) band radiation thermometer with a highly specialized stray and reflected radiation shroud attachment is used as the detector system, allowing for convenient handheld field measurements. The performance and accuracy of the system have been compared with NMIA’s reference emissometer systems for a number of typical material samples, demonstrating its capability to measure the absolute thermal emissivity of these very highly reflective foils with an uncertainty of better than \(0.007, k = 2.07, 95\,\%\) .

This is the final report on the Euramet RMO extension of Key Comparison 5 entitled 'Comparison of local realizations of the ITS-90 between silver point and 1700 °C using vacuum tungsten strip lamps as transfer standards'. The local realizations in this range of the ITS-90 and the corresponding uncertainties are given for the eight national metrology institutes who participated in the comparison. The deviations of the participants' data from the previously established and accepted CCT-K5 key comparison reference values (KCRV) are presented in this report. For some temperature scale, significant unresolved deviations (SUDs) are observed between the participants' data and the KCRV. These SUDs are briefly discussed in this report. The interlaboratory cross-equivalence values for the different temperature realizations are also provided in this report. Prior to the finalization of this report, the draft A was presented to the participants for their comments and approval. Some minor comments received from the participants were included in the draft B. The draft B was approved by all participants for submission to the Euramet RMO for further review by the CCT-WG7 working group. The comments received from the reviewers of the draft B are incorporated in this final report. This final report has been officially approved by the chairman of the CCT-WG7. 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).

Reflective metal foil is widely used to reduce radiative heat transfer within the roof space of buildings. Such foils are typically mass-produced by vapor-deposition of a thin metallic coating onto a variety of substrates, ranging from plastic-coated reinforced paper to "bubble-wrap". Although the emissivity of such surfaces is almost negligible in the thermal infrared, typically less than 0.03, an insufficiently thick metal coating, or organic contamination of the surface, can significantly increase this value. To ensure that the quality of the installed insulation is satisfactory, Australian building code AS/NZS 4201.5:1994 requires a practical agreed method for measurement of the emissivity, and the standard ASTM-E408 is implied. Unfortunately this standard is not a "primary method" and requires the use of specified expensive apparatus and calibrated reference materials. At NMIA we have developed a simple primary technique, based on an apparatus to thermally modulate the sample and record the apparent modulation in infra-red radiance with commercially available radiation thermometers. The method achieves an absolute accuracy in the emissivity of approximately 0.004 (k=2). This paper theoretically analyses the equivalence between the thermal emissivity measured in this manner, the effective thermal emissivity in application, and the apparent emissivity measured in accordance with ASTM-E408.

The article presents the results of the EURAMET Project No. 927 "Comparison of blackbodies for calibration of infrared ear thermometers (IRETs)". The objective of the comparison was to determine the agreement of blackbodies used for the calibration of IRETs among European national laboratories. To verify the accuracy of an IRET, a suitable blackbody (BB) is needed. Such a blackbody related to the EN standard, designed for the calibration of ear thermometers and immersed in a stirred water bath, was provided for the comparison by the pilot laboratory. The pilot provided also the transfer IRET and organized the comparison.

Solid-state lighting and display technology are under rapid development. Photometric measurement devices such as imaging systems or tristimulus sensors encounter complex spatial, spectral and temporal conditions. Sufficiently large uniform calibration sources are required to adequately match the field application and to facilitate acceptable calibration uncertainties. We present a relatively compact, large-area uniform source employing plate diffusers and a patterned mask. The source is easily configured with colour-selectable, temperature-stabilized high power LED modules. We achieve 99% spatial uniformity within a 16 cm x 16 cm square field with Lambertian angular characteristics.

Below the freezing point of silver, radiation thermometers are generally calibrated by implementing the multi-point interpolation method using blackbody measurements at three or more calibration points, rather than the ITS-90 extrapolation technique. The interpolation method eliminates the need to measure the spectral responsivity and provides greater accuracy at the longer wavelengths required below the silver point. This article identifies all the sources of uncertainty associated with the interpolation method, in particular, those related to the reference blackbody temperatures (either variable-temperature or fixed-point blackbodies) and to the measured thermometer signals at these points. Estimates are given of the ‘normal’ and ‘best’ uncertainties currently achievable. A model of the thermometer response is used to propagate all the uncertainties at the reference points and provide a total uncertainty at any temperature within the calibration range. The multi-point method has the effect of constraining the total uncertainty over this range, unlike the ITS-90 technique for which the uncertainties propagate as T 2. This article is a joint effort of the working group on radiation thermometry of the Consultative Committee for Thermometry (CCT), summarizing the knowledge and experience of all experts in this field.

In the first half of 2005, Nederlands Meetinstituut Van Swinden Laboratorium B.V. (NMi VSL) redesigned their facilities for radiation thermometry in a new laboratory building and an opportunity arose to implement new measurement methods. The new facility is used for ITS-90 realization and dissemination in the temperature range from  − 50 °C to 3,000 °C. A study was performed to compare a silver-point realization with a fixed-point blackbody radiator (FP-BBR) to a sodium heat-pipe blackbody radiator (HP-BBR) traceable via a HTSPRT to a contact thermometry silver point. It was found that the fixed-point realization transfer to the sodium heat pipe results in an uncertainty from 0.2 K to 2.4 K for the ITS-90 over the temperature range from 961.78 °C to 3,000 °C.

This article introduces a new technique for measuring the size-of-source effect in radiation thermometers. It is based on scanning a thermometer across an aperture and extracting the size-of-source effect data from the residual signal, and is similar to the commonly used indirect method. The method has several advantages including speed, an ability to cover wide angles, and amenability to automation, at the expense of some added mathematical complexity. Results compare favorably with the frequently used indirect method of measuring the size-of-source effect.

Medical diagnostics and clinical practice rely extensively on test and measurement instrumentation. It is therefore of paramount importance that test and measurement instrumentation provides reliable data of sufficient stability, within appropriate limits of accuracy. At the same time the intended purpose of a particular measuring instrument has to be taken into account. The essential problem of every measuring instrument is that it measures and indicates basically what appears at the input of the measuring instrument, which might be significantly different from the real condition of a measurand. Namely, it is assumed that a measurand is stable, repeatable, and relatively unsusceptible to environmental influences. All these requirements are difficult to assure in a biological system and especially difficult in medical practice. Technology could easily provide high-resolution measurements, but due to natural instability of a measurand and various influential parameters the measurement uncertainty is inevitable. Sometimes even gross measurement errors are introduced. To achieve the expected accuracy for intended purpose is therefore much more demanding than merely relying on manufacturers' specifications. This paper describes and analyses the mentioned dilemmas in the case of widely used infrared ear thermometers, with their benefits and limitations, as well as with regard to the European technical regulation in the field of medical devices.

Recent international comparisons [1,2] and key comparisons have shown that the realization of the International Temperature Scale of 1990 (ITS-90) above the freezing point of silver and its dissemination is more difficult than expected. In many cases, the deviations of the local scale realizations were larger than the combined estimated uncertainties could reasonably justify. On the other hand, it must be considered that the realization of the ITS-90 by radiation thermometry is a complex exercise involving a large number of operations with many influencing parameters. Furthermore, the key comparisons need a unified approach to the treatment of uncertainties. Consequently, a rigorous standard approach for the calculation of uncertainties is necessary. In this paper three different operational schemes have been identified for realizing the ITS-90 by radiation thermometry. For all three schemes an analysis is presented of the baseline parameters underlying the scale realization above the freezing point of silver with respect to their contribution to the uncertainty budget. The paper is a joint effort of the working group on radiation thermometry of the Consultative Committee for Thermometry (CCT) summarizing the knowledge and experience of all experts in this field.

Here we report on an alternative approach for making spectral irradiance measurements of radiation sources traceable, employing our monochromator-based absolute cryogenic radiometer (ACR) facility to its full extent. The method makes use of the continuously tunable absolute radiant flux emerging from the ACR facility to characterize and calibrate the spectral irradiance responsivity of a second adjacent double-monochromator system. This system will be part of a new facility at NMi-VSL, called SIR, that will be used to measure spectral irradiance distributions of radiation sources from the ultraviolet to the far infrared. Following this traceability route, a fully characterized high-temperature Planckian radiator is not needed. Proof-of-principle measurements in the visible part of the spectrum show very encouraging results. Although the new facility is under construction, the theoretical background and a schematic description will be presented in this paper.

In the course of the EC-funded project TRIRAT ("TRaceability in Infrared Radiation Thermometry") an international comparison of local radiation temperature scales took place among fourteen laboratories in the temperature range from 150 degreesC to 962 degreesC. This paper describes the equipment and the transfer standards used for the comparison. The results and the procedures adopted for deriving a "comparison reference value" (CRV) and the degree of equivalence of each laboratory with respect to the CRV are then discussed. The different arrangements adopted for the calibration of the thermometers and additional experimental investigations allowed an analysis on the effect of some influencing parameters, e.g., the size of source effect (SSE), to be performed and indications on the most convenient experimental arrangements to be derived.

On the basis of two specific examples we present a comparison of two different schemes I and II underlying the calibration of lens-based infrared radiation thermometers covering the range from - 50 degreesC to 300 degreesC. Scheme I is based upon the determination of the appropriate instrument functions, viz. relative spectral responsivity s(lambda) and non-linearity NL. In this scheme only two reference points are additionally needed to establish an equation, which relates measured signals S to temperatures T. Scheme II relies on the calibration of the thermometers, as 'black boxes', against a range of temperatures involving several variable-temperature blackbody simulators.

The project "Traceability in infrared radiation thermometry from -50 degreesC to 800 degreesC" (TRIRAT) was started in 1996 with one of the objectives to improve, on an international level, the uncertainty associated with the realisation of the temperature scale for radiation thermometry below the Ag-point. Next to a review of the TRIRAT program, we report on the transfer-standards being employed for the low-temperature regime intercomparison.