Iodine stabilized laser with three internal mirrors

The construction and operation of an He-(20)Ne laser stabilized by saturated absorption in (129)I(2) vapor are described. The laser is of fused silica construction with internal mirrors. The interaction of the iodine absorber with the oscillating mode is modified by the use of a three-mirror cavity with a control system employing simultaneously first- and third-harmonic error sensing. Measurements are presented of the frequency stability of the laser and its wavelength against the (86)Kr standard. If the Rowley-Hamon model of the krypton line profile is assumed and the defined wavenumber is assigned to the mean of the peak and the centroid, the measured wavelength of the m hyperfine component is 632991 327 +/- 0.7 fm.