Philos Trans A Math Phys Eng Sci. 2016 Mar 28;374(2064):20150041. doi: 10.1098/rsta.2015.0041.

Thermodynamic temperature by primary radiometry.

Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

Klaus Anhalt, Graham Machin

PMID: 26903102 DOI: 10.1098/rsta.2015.0041

Abstract

Above the freezing temperature of silver (1234.93 K), the International Temperature Scale of 1990 (ITS-90) gives a temperature, T90, in terms of a defining fixed-point blackbody and Planck's law of thermal radiation in ratio form. Alternatively, by using Planck's law directly, thermodynamic temperature can be determined by applying radiation detectors calibrated in absolute terms for their spectral responsivity. With the advent of high-quality semiconductor photodiodes and the development of high-accuracy cryogenic radiometers during the last two decades radiometric detector standards with very small uncertainties in the range of 0.01-0.02% have been developed for direct, absolute radiation thermometry with uncertainties comparable to those for the realization of the ITS-90. This article gives an overview of a number of design variants of different types of radiometer used for primary radiometry and describes their calibration. Furthermore, details and requirements regarding the experimental procedure for obtaining low uncertainty thermodynamic temperatures with these radiometers are presented, noting that such radiometers can also be used at temperatures well below the silver point. Finally, typical results obtained by these methods are reviewed.

© 2016 The Author(s).

Keywords: primary thermometry; radiation thermometry; radiometry

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't
• Review