Resolution-CGPM-20-4

Resolution 4 of the 20th CGPM

Revision of the mise en pratique of the definition of the metre

The 20th Conférence Générale des Poids et Mesures,

recalling

  • that in 1983 the 17th Conférence Générale des Poids et Mesures adopted a new definition of the metre,
  • that in the same year the Conférence Générale invited the Comité International des Poids et Mesures
  • to draw up instructions for the practical realization of the metre,
  • to choose radiations which can be recommended as standards of wavelength for the interferometric measurement of length and draw up instructions for their use,
  • to pursue studies to improve these standards and, in due course, to extend or revise these instructions,
    • that in response to this invitation the Comité International made recommendations in 1983 concerning the practical realization of the metre (the mise en pratique),

    considering

    • that science and technology continue to demand improved accuracy in the realization of the metre,
    • that since 1983 work in national laboratories, the Bureau International des Poids et Mesures and elsewhere has substantially improved the reproducibility of radiations which are suitable for the practical realization of the metre,
    • that such work has also substantially reduced the uncertainty in the determined values of the frequencies and wavelengths of some of these radiations,

    welcomes the adoption by the Comité International of a revised mise en pratique of the definition of the metre, taking account of the results of this new work,

    and

    recommends that national laboratories pursue their research on optical wavelength and frequency standards to improve yet further the experimental basis of the Système International d'Unités.

    reference The reader should note that the official version of this Resolution is the French text

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