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
·ν and a stability of 1.4 × 1013·ν for an observation time τ = 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· ν can be expected. Common and convenient operating conditions have been found at both wavelengths.