A transportable methane stabilized He-Ne laser

A transportable methane stabilized He-Ne laser system has been built for a wavelength-optical frequency standard according to the operating conditions of the Comité Consultatif pour la Definition du Meter (CCDM) recommendation. For estimation of the stabilized laser system, an offset-locked laser system has also been developed by means of a phase comparison technique. The frequency stability and the resettability of the stabilized laser system is estimated to be 2.5 × 10⁻¹²τ ^−1/2 and 1 × 10⁻¹¹, respectively.