CO2 OSO4 LASERS AS FREQUENCY STANDARDS IN THE 29 THZ RANGE/

The CO2 lasers, frequency stabilized on OsO4 transitions around 29 THz , are successfully used as secondary references for visible frequency synthesis and also for high-accuracy spectroscopy in the infrared doma in, The BNM-LPTF CO2/OsO4 frequency standards exhibit high metrologica l performances: a long term reproducibility of +/-10 Hz (1 sigma = 2 x 10(-13)) and a stability sigma(y) = 6.6 x 10(-14)/root tau uith a Fli cker plateau of 4 x 10(-15) (Delta nu/nu 0.1) for 300 s to 10(3) s ave raging times, These results and a preliminary study of the main effect s which can induce frequency shifts are reported.