A transportable gallium melting point blackbody for radiation thermometry calibration

Machin, G.; Chu, Brian

doi:10.1088/0957-0233/9/10/002

Cited by 4 publications

(5 citation statements)

References 3 publications

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“…5 Similarly, in the range from -20 • C to +100 • C the results obtained with an ammonia and a water heat-pipe BBR (HP-BBRs) agreed with results derived from an internal standard fluid-bed BBR, of an essentially different design, to within 50 mK. 6,7 Next to ammonia and water HP-BBRs also two portable fixed-point BBRs, operating at the Gallium-and Zinc-point, were constructed 8,9 and characterized. These FP-BBRs were used in the project to accompany TRTs in order to check correct operation and to monitor possible long-term drift.…”

Section: Dissemination Of Its-90; Improving Traceabilitymentioning

confidence: 73%

Traceability toward industry: from TRIRAT to ILART

2003

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The impact of thermal radiation and its associated radiance temperature on nearly all facets of technology and society is tremendous. Reliable temperature measurements are in that context of vital importance in many areas in science, technology, industry and environmental protection. This implies the use of a sound traceability framework, involving accurate reference standards to begin with and a calibration procedure for radiation thermometers that incorporates all sources of measurement errors (uncertainties). Latter procedure should be two-fold; first a traceable comparison is made against a blackbody radiator, then the instrument is evaluated and/or calibrated in its application.In this paper all three traceability steps will be addressed, that is, the dissemination of the international temperature scale of 1990 (ITS-90) and the initial and on-site calibration of radiation thermometers. First two steps were investigated in detail and improved on European level in the TRIRAT program that was funded by the European Community. This included international intercomparisons for radiation thermometer calibrations and recommendations for the standardization and testing of infrared radiation thermometers as transfer standards. An other project, ILART, bridges the gap in traceability between initial calibrated radiation thermometers and their industrial application. It involves realization of a portable calibration facility, intrinsically insensitive for surface emissivity and reflection error using active two-color thermometry.

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Section: Dissemination Of Its-90; Improving Traceabilitymentioning

confidence: 73%

Traceability toward industry: from TRIRAT to ILART

2003

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“…The Ga-point blackbody is described in [11]. It uses 1.1 kg of 99.9999% purity gallium enclosed in a cell made of black Teflon, which is heated from the outside with circulating water.…”

Section: Calibration Of the Ambermentioning

confidence: 99%

“…above the indium point (156.5985 • C) [3], and there are no fixed-point blackbodies available below 0 • C. In the temperature range around room temperature where most infrared radiation thermometers operate in the wavelength range of (8)(9)(10)(11)(12)(13)(14) µm, examples of infrared thermometers calibrated at fixed-point blackbodies with cavity apertures large enough to accommodate the relatively large target size of the thermometers can be found [4]. However, in practice calibrations of these thermometers are performed predominantly traceable to contact thermometry.…”

Section: Introductionmentioning

confidence: 99%

“…An exception to this is the National Physical Laboratory (NPL) Absolute Measurements of Blackbody Emitted Radiance (AMBER) radiometer [6]. This instrument detects thermal radiation in the wavelength range of (9)(10)(11) µm and has measurement temperature range from below −50 • C to above 50 • C. Although originally intended as an absolute radiometer that measures thermodynamic temperature without reference to fixed points, AMBER was eventually established as a relative radiometric measurement instrument relying on a fixed-point blackbody calibration at a single reference temperature at the melting point of pure gallium (Ga) (29.7646 • C) [7]. This radiometric calibration scheme is similar to the ITS-90 definition above the silver point (defined by the ratio against the blackbody radiance at one of the fixed-point temperatures of freezing silver (961.78 • C), gold (1064.18 • C) or copper (1084.62 • C)) [1], although at a much lower temperature.…”

Section: Introductionmentioning

confidence: 99%

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A novel radiometric calibration of an infrared thermometer

Yamada,

Harris,

Theocharous

et al. 2023

Metrologia

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A new temperature calibration scheme was proposed and implemented on the NPL infrared radiometer AMBER operating in the wavelength range from 9 µm to 11 µm and equipped with a cryogenically cooled mercury cadmium telluride detector. The scheme involves measurements of the relative spectral responsivity of the filter radiometer including the spectral transmittance of the window and lens. It requires calibration at two reference temperatures, but does not involve measurement of the zero-radiance signal. The scheme uses a Ga-point blackbody as one reference point, and a variable temperature blackbody source at close to ‒30 °C with its temperature measured with a standard platinum resistance thermometer as the other. The measured temperature was compared using the variable temperature blackbody as the source against the temperature measured by the standard platinum resistance thermometer and agreement within the uncertainties was confirmed at intermediate temperatures. The scheme has the advantage that it makes full use of the small uncertainty realised by the fixed-point blackbody. The scheme was successfully implemented in an international comparison of sea surface temperature measuring radiometers where AMBER served to provide the reference.

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“…In the past, it has been demonstrated that it is possible to build a high-quality gallium blackbody with a small aperture that can operate in vacuum [3] or in the open air [4]. To reduce the influence of background conditions on a BB output, one can decrease the radiation losses through the BB cavity aperture by installation of a concentrator of radiation in front of the cavity.…”

Section: Introductionmentioning

confidence: 99%

Design and Evaluation of Large-Aperture Gallium Fixed-Point Blackbody

Khromchenko¹,

Mekhontsev

Hanssen

2008

Int J Thermophys

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To complement existing water bath blackbodies that now serve as NIST primary standard sources in the temperature range from 15 • C to 75 • C, a gallium fixedpoint blackbody has been recently built. The main objectives of the project included creating an extended-area radiation source with a target emissivity of 0.9999 capable of operating either inside a cryo-vacuum chamber or in a standard laboratory environment. A minimum aperture diameter of 45 mm is necessary for the calibration of radiometers with a collimated input geometry or large spot size. This article describes the design and performance evaluation of the gallium fixed-point blackbody, including the calculation and measurements of directional effective emissivity, estimates of uncertainty due to the temperature drop across the interface between the pure metal and radiating surfaces, as well as the radiometrically obtained spatial uniformity of the radiance temperature and the melting plateau stability. Another important test is the measurement of the cavity reflectance, which was achieved by using total integrated scatter measurements at a laser wavelength of 10.6 µm. The result allows one to predict the performance under the low-background conditions of a cryo-chamber. Finally, results of the spectral radiance comparison with the NIST water-bath blackbody are provided. The experimental results are in good agreement with predicted values and demonstrate the potential of our approach. It is anticipated that, after completion of the characterization, a similar source operating at the water triple point will be constructed.

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A transportable gallium melting point blackbody for radiation thermometry calibration

Cited by 4 publications

References 3 publications

Traceability toward industry: from TRIRAT to ILART

Traceability toward industry: from TRIRAT to ILART

A novel radiometric calibration of an infrared thermometer

Design and Evaluation of Large-Aperture Gallium Fixed-Point Blackbody

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