Recent Progresses in He-Ne Lasers Stabilized to 127I2

The stabilization of a He-Ne (Helium-Neon) laser to hyper-fine structure (HFS) components of the P(48) 11-3 transition of 127I2 at 612 nm observed in an external iodine cell, may give a frequency reproducibility of ??5 kHz or ??1 ?? 10-11???? and a stability of 1.4 ?? 1013???? for an observation time ?? = 100 s. From 3He-22Ne lasers stabilized to HFS components of 127I2 observed in an intracavity cell, both at 612 and 640 nm wavelengths, a reproducibility of ??2 ?? 10-10?? ?? can be expected. Common and convenient operating conditions have been found at both wavelengths.