Abstract

Using Doppler-free two-photon spectroscopy of the 2S_1/2-nD_5/2(n=8, 10, 12) transitions in atomic hydrogen, we obtained in 1988^[1] a determination of the Rydberg constant with an uncertainty of 1.7 parts in 10¹⁰. In this measurement, the wavelength of the transitions studied was measured by an interferometric comparison with that of an optical standard, an iodine-stabilized He-Ne laser at 633 nm. In the near future, this precision could be improved by one order of magnitude for two reasons: firstly, the frequency of the He-Ne standard, then known with a precision of only 1.6 parts in 10¹⁰, is currently being remeasured at the L.P.T.F. (Paris) by A. Clairon and his collaborators; secondly, we have now replaced our wavelength calibration-limited to a few parts in 10¹¹–by a direct frequency comparison of the 2S-8S/8D lines with two optical standards.

© 1992 IQEC