THE REALIZATION AND THE DISSEMINATION OF THE DETECTOR-BASED KELVIN |
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| Howard W. Yoon, Charles E. Gibson, David W. Allen, Robert D. Saunders, Maritoni Litorja, Steven W. Brown, George P. Eppeldauer, Keith R. Lykke |
- Abstract:
- In the International Temperature Scale of 1990 (ITS-90), temperatures above the freezing temperature of silver are determined with radiation thermometers calibrated using spectral radiance ratios to one of the Ag-, Au- or Cu-freezing temperature blackbodies and the Planck radiance law. However, due to the use of spectral radiance rats, the temperature uncertainties of the ITS-90 increase as the square of the temperature ratios. Recent acoustic- gas thermometry measurements have also shown that the underlying thermodynamic temperatures used in the radiance ratios in determining the Ag- and Au-fixed point temperatures could be in error. Since the establishment of ITS-90, much progress has been made in the development of radiation thermometers and blackbody sources. Cryogenic electrical-substitution radiometry is widely used in detector and radiometer calibrations, and stable, high-temperature metal-carbon eutectic blackbodies are under development. Radiation thermometers can be calibrated for absolute radiance responsivity, and blackbody temperatures determined from measurement of optical power without the use of any fixed points thus making possible direct dissemination of thermodynamic temperatures. We show that these temperatures can be measured with lower final uncertainties than the ITS-90 derived temperatures. We have shown that these “Absolute Pyrometers” can be used to determine the thermodynamic temperatures of the ITS-90 fixed points as well as also being used in bilateral comparisons of temperature scales. Many leading national measurement institutes are already utilizing detector- based temperatures in establishing spectroradiometric source scales. We believe, that due to these developments, the international temperature scale should be revised so that a thermodynamic temperature scale can be directly disseminated.
- Download:
- IMEKO-TC12-2004-PL-004.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC12
- Event name:
- TEMPMEKO 2004
- Title:
- 9th International Symposium on Temperature and Thermal Measurements in Industry and Science
- Place:
- Cavtat-Dubrovnik, CROATIA
- Time:
- 21 June 2004 - 25 June 2004