The Reproducibility of 633-nm Lasers Stabilized by 127I2

International intercomparison of the wavelength of iodine-stabilized lasers

“…NBS-4 is a relatively short device [2] with a cavity interaction length of L = 0.52 m. It has been used as a clock since July 1975. The main reasons for this are twofold: 1) although a full accuracy evaluation can be performed on NBS-4, it is more difficult than for NBS-6.…”

“…Particular attention has been paid to improving the long-term stability of NBS-4 and in evaluating the limitations of an absolute frequency determination using NBS-6. Most of the construction details of both standards are reported elsewhere [1], [2] and are not repeated here.…”

“…The most recent hardware changes [2] were those completed on NBS-6 (formerly called NBS-5), which included provisions for increased pumping speed and improved beam reversal capability. Larger pumps were installed to reduce beam scattering resulting in pressures < 1.3 X 10~5 N/m 2 (typically 1-3 X 10" 6 detector assemblies were installed on both ends of NBS-6.…”

Frequency stabilization of 633-nm He-Ne laser by using frequency modulation spectroscopy of127I2 enhanced by an external optical cavity

“…It is reported that in the absorption line due to R(127) transition the coefficient of frequency shift due to the change in vapor pressure is about 7.6 kHz/Pa [18]. Here, the dependence of frequency shift on iodine vapor pressure in stabilization to P(33) transition a-component is investigated.…”