127I2-Stabilized 3He-22Ne Laser at 640 nm Wavelength

Strong saturated absorption features attributed to hyper-fine components of two different 127I2-transitions P(10) 8-5 and R(16) 8-5 were observed within the tuning range at 640 nm of a 3He-22Ne laser. The maximum peak height was 10 percent of the laser power at a linewidth of 5 MHz (FWHM). The HFS coupling constants of the P(10) 8-5 line were determined resulting in a ?eqQ = 1950.58 MHz. For the HFS component "a9" the dependencies of the frequency ? on modulation width, iodine pressure, and output power are similar to those of the I2-stabilized He-Ne laser at 633 nm wavelength. The frequency repeatability was about 10-11 ?. The relative frequency reproducibility was better than 10-10.