Frequency shift of the λ =3.39 μ methane transition in a ring laser field

An investigation is made of the reproducibility of an He–Ne/CH₄ frequency standard with a ring resonator. The dependence of the radiation frequency of such a stabilized laser on the saturation parameter of the absorbing medium is determined. It is shown that "weak" transitions in the hyperfine structure of the methane absorption line substantially influence the behavior of this dependence.