Accuracy of the computer-controlled laser frequency standards based on resolved hyperfine structure of a methane line

Results of 2-year frequency comparisons of our transportable He-Ne laser standard stabilized on a component of the magnetic hyperfine structure (MHFS) of the F/sub 2//sup 2/ line of methane /spl lambda/=3.39 /spl mu/m, with our stationary laser using resolved recoil doubler as reference are presented. The absolute frequency of the transportable laser measured at PTB (Physikalisch-Technische Bundesanstalt, Braunschweig, Germany), using the radio-optical frequency chain, was transferred to the stationary device. On the basis of the theoretical model of the line shape, the frequency of unperturbed transition has peen calculated.<
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