International comparisons of He-Ne lasers stabilized with I-127(2) at lambda approximate to 633 nm (July 1993 to September 1995) Part V: Comparison of Asian-Pacific and South African lasers at lambda approximate to 633 nm

This paper reports the fifth set of results of a series of grouped laser co mparisons from national laboratories undertaken by the Bureau International des Poids et Mesures (BIPM) at the request of the Comite Consultatif pour la Definition du Metre (CCDM, now the Consultative Committee for Length, CC L), during the period July 1993 to September 1995. The results of this comparison, involving six lasers from five countries an d the BIPM, meet the goals set by the CCDM in 1992 and adopted by the Comit e International des Poids et Mesures (CIPM) the same year. The standard unc ertainty (1 sigma) of the frequency of the He-Ne laser stabilized on the sa turated absorption of I-127(2) at lambda approximate to 633 nm is reduced t o a level of 12 kHz (2.5 parts in 10(11)) when the lasers compared meet the recommended values of the parameters. The lasers were first compared with the BIPMP3 or the CSIRO1 lasers, with a ll the lasers set to the parameter values normally used in each laboratory; the results ranged from -48.3 kHz to 13.8 kHz. After checking and readjust ing the values of all the parameters, the range was reduced to -14.7 kHz to 10.4 kHz. Under the latter conditions, the average frequency difference of the group of lasers with respect to the BIPM4 laser was -0.5 kHz with a st andard uncertainty (1 sigma) of 8.5 kHz. The best relative frequency stabil ities, with Allan standard deviations of about 3.5 parts in 10(12) and 3.5 parts in 10(13), were observed with sampling times of 8 s and 2048 s, respe ctively.