Absolute Spectral Radiometric Determination of the Thermodynamic Temperatures of the Melting/Freezing Points of Gold, Silver and Aluminium

Fox, Nigel; Martin, John; Nettleton, D. H.

doi:10.1088/0026-1394/28/5/001

Cited by 45 publications

(39 citation statements)

References 21 publications

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“…Because the blackbody's spectral radiance can be entirely described by its temperature (through Planck's law), a single FR reading is sufficient to determine the entire spectrum. In the early 1990s, NPL pioneered the absolute radiometric measurement of blackbody temperature (filter radiometry) with measurements of the transition temperature of fixedpoint blackbodies (the freezing temperature of metals at around 1000 • C) and measured the radiance of these blackbodies with uncertainties of 0.06 per cent (k = 2) [62]. Today, the radiometry and thermometry communities are using the same techniques to calibrate novel high-temperature fixed points as references for high temperature measurement (approx.…”

Section: (E) Filter Radiometers In Standards Laboratoriesmentioning

confidence: 99%

Accurate radiometry from space: an essential tool for climate studies

Fox

Kaiser-Weiss

Schmutz

et al. 2011

Phil. Trans. R. Soc. A.

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The Earth's climate is undoubtedly changing; however, the time scale, consequences and causal attribution remain the subject of significant debate and uncertainty. Detection of subtle indicators from a background of natural variability requires measurements over a time base of decades. This places severe demands on the instrumentation used, requiring measurements of sufficient accuracy and sensitivity that can allow reliable judgements to be made decades apart. The International System of Units (SI) and the network of National Metrology Institutes were developed to address such requirements. However, ensuring and maintaining SI traceability of sufficient accuracy in instruments orbiting the Earth presents a significant new challenge to the metrology community. This paper highlights some key measurands and applications driving the uncertainty demand of the climate community in the solar reflective domain, e.g. solar irradiances and reflectances/radiances of the Earth. It discusses how meeting these uncertainties facilitate significant improvement in the forecasting abilities of climate models. After discussing the current state of the art, it describes a new satellite mission, called TRUTHS, which enables, for the first time, high-accuracy SI traceability to be established in orbit. The direct use of a 'primary standard' and replication of the terrestrial traceability chain extends the SI into space, in effect realizing a 'metrology laboratory in space'.

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Section: (E) Filter Radiometers In Standards Laboratoriesmentioning

confidence: 99%

Accurate radiometry from space: an essential tool for climate studies

Fox

Kaiser-Weiss

Schmutz

et al. 2011

Phil. Trans. R. Soc. A.

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“…Filter radiometry is based on the measurement of total spectral flux from a blackbody source within a narrow wavelength range [1,2]. From this measurement, and Planck's law, the temperature of the blackbody source can be determined directly.…”

Section: Introductionmentioning

confidence: 99%

The Double-Wavelength Technique—An Alternative Technique to Determine Thermodynamic Temperature

et al. 2008

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Filter radiometry provides thermodynamic temperatures traceable to a cryogenic radiometer. An alternative technique is possible which provides absolute thermodynamic temperature through a different traceability chain, with the radiometric measurements purely relative. If this technique could be experimentally realized with similar uncertainties to those associated with filter radiometry, then this would provide a metrologically valuable 'second opinion' that would test for systematic effects common to all filter radiometry measurements. This paper describes the theoretical analysis prior to an experimental investigation of this technique. This theoretical analysis implies that with Re-C and Cu as the two blackbodies, the Re-C temperature can be determined with an uncertainty of approximately twice that expected with filter radiometry. For higher-temperature metal-carbide/carbon eutectics, the uncertainty difference would be smaller.

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“…The absolute irradiance responsivity of the FR is the prerequisite characteristic before it can be applied to absolute radiation thermometry. The calibration of the FR is performed in a two-step process at NIM as at other NMIs [8][9][10]. First, a trap detector is calibrated against the cryogenic radiometer (CR) at several discrete laser lines.…”

Section: Introductionmentioning

confidence: 99%

Calibration of the Irradiance Responsivity of a Filter Radiometer for T Measurement at NIM

Yuan

Hao

et al. 2011

Int J Thermophys

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At the National Institute of Metrology of China (NIM), silicon photodiode-based narrow-band interference filter radiometers (FRs) have been designed for the radiometric determination of the thermodynamic temperature. The FR calibrations were performed on a new spectral comparator with a trap detector which was calibrated against the cryogenic radiometer at several discrete laser lines. The new spectral comparator is constructed from two grating monochromators assembled to give lower stray light and higher transmitted flux. Applying a transmittance measurement of the filter in the out-of-band region and careful control of the temperature, the irradiance responsivity of a 633 nm centered FR has been obtained over a dynamic range of nearly eight decades in the wavelength range from 450 nm to 1200 nm. The relative standard uncertainty of the responsivity is also analyzed and estimated to be less than 7 × 10 −4 at the 1 σ level.

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Absolute Spectral Radiometric Determination of the Thermodynamic Temperatures of the Melting/Freezing Points of Gold, Silver and Aluminium

Cited by 45 publications

References 21 publications

Accurate radiometry from space: an essential tool for climate studies

Accurate radiometry from space: an essential tool for climate studies

The Double-Wavelength Technique—An Alternative Technique to Determine Thermodynamic Temperature

Calibration of the Irradiance Responsivity of a Filter Radiometer for T Measurement at NIM

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