Current state of the problem of the definition of the meter

Possible ways of increasing the accuracy of definition of the meter in terms of the wavelength of laser radiation are discussed. A review is given of published work on saturated absorption of laser radiation in iodine and methane and on measurements of the wavelength of stabilized lasers in the visible and infrared regions of the spectrum. Values are reproduced for the wavelengths of lasers stabilized by saturated absorption in iodine and methane and for the velocity of light, which have been recommended as standards for measurements of length and wavelength by the Comité Consultatif pour la Définition du Métre (CCDM) of the Comité international des Poids et Mesures.