COMPARISON OF I-127(2)-STABILIZED HE-NE LASERS AT 633 NM BETWEEN THE MIKES AND THE BIPM

The result of a comparison of I-127(2)-stabilized He-Ne lasers at 633 nm between the MIKES and the BIPM is reported. The averaged frequency difference over absorption components d, e, f, g of the iodine molecul ar transition 11-5, R(127) between laser MRI3 and laser BIPM4 was nu(M RI3) - nu(BIPM4) = -1,4 kHz with a standard uncertainty (1 sigma) s = 0,4 kHz. The observed relative frequency stability determined by measu rement of the Allan variance was 1,4 x 10(-13) for an averaging time o f 5000 s. To investigate the repeatability of the lasers, iodine absor ption cells were installed and measured in both laser MRI3 and laser B IPM7, taking laser BIPM4 as the reference. The frequency stabilization of laser MRI3 at the fifth harmonic of the modulation was tested.