Iodine-stabilized He-Ne laser as a standard in the visible range

When an absorption cell filled with iodine vapor is placed in the resonator of a He-Ne laser emitting in the optical range, small peaks are observed in the tuning curve, which are caused by saturated absorption in the iodine vapor. The use of these peaks in the frequency stabilization of the laser is discussed. Design and characteristics of a laser so stabilized are examined. Fractional frequency deviations on the order of 2 times 10 to the minus 13th power have been obtained for a counting time of 1,000 sec. The frequency of a laser stabilized in the (I-129)2 absorption line depends linearly on the iodine vapor pressure.