Abstract. The absolute optical frequency of a 633 nm, I₂-stabilized He–Ne laser system is measured with a femtosecond laser frequency comb. Results over a three-year period using chain- and comb-based measurements yield an operating frequency of f_f = (473 612 353 602 850 ± 570) Hz for the INMS 3 laser stabilized to the f or a₁₆ component of the 11-5 R(127) transition in ¹²⁷I₂ at the operating conditions specified for the realization of the recommended value of this radiation. The frequency of the NRC INMS 2 laser system has recently been measured with combs at NRC and BIPM and was shown to be reproducible to better than 600 Hz (1 × 10⁻¹²) after transport. These results indicate the high level of reproducibility attainable by such widely used optical frequency standards.

Print publication: Issue 3 (June 2004)
Received 8 December 2003
Published 7 April 2004