Introduction of the International Practical Temperature Scale 1968: some effects in relation to light sources,colour temperature,and colorimetry

Abstract

The International Practical Temperature Scale of 1968 has replaced the IPTS-48, in this country, since January 1, 1969. In consequence, there are certain adjustments or changes in assigned temperature values including, for example, that of the gold point. In the range above the gold point, the changes are of the order of several kelvins. This paper summarises the basis and nomenclature of the IPTS-68, and explains the possible effects of the changes in situations where lamps are used as working standards of colour, colour temperature, or spectral energy distribution. The effect on the computed value of Km is also referred to. The paper concludes with a short table of equivalent 1968/48 temperature values.

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References

The International Practical Temperature Scale of 1968, HMSO.

Changes in the numerical values of temperature resulting from the adoption of the International Practical Temperature Scale 1968 (on request from Director, National Physical Laboratory, Teddington, Middx.)

Tables of spectral power distribution of tungsten and black body radiators, with explanatory introduction (enquiries to Superintendent, Division of Quantum Metrology, National Physical Laboratory, Teddington, Middx.)