International comparisons of He-Ne lasers stabilized with I-127(2) at lambda approximate to 633nm (July 1993 to September 1995) - Part III: Second comparison of Eastern European lasers at lambda approximate to 633nm

This paper reports the third 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) for the period July 1993 to September 1995. T he results of this comparison, involving eight lasers, are comparable with those obtained during a first comparison in 1988 involving most of the same national laboratories. The lasers were first compared with the BIPM lasers with the parameters set to the values normally used in each laboratory, th e results then ranged from -23 kHz to +28.2 kHz. After checking and readjus ting the values of all the parameters, the range was reduced to -20.4 kHz t o +9.7 kHz. Under the latter conditions, the average frequency difference o f the group of lasers, with respect to the BIPM4 laser, was -5.8 kHz with a standard uncertainty (1 sigma) of 12.3 kHz. Typical frequency stabilities with Allan standard deviations of about 1.8 x 10(-11) and 1.8 x 10(-12) wer e observed with sampling times of 1 s and 100 s, respectively.