Romanian primary length standards involved in international comparisons

One of the three methods specified for the practical realization of the meter uses molecular transitions. He-Ne lasers operating at 633 nm wavelength and frequency stabilized by saturated absorption in 127I2 were built at the National Institute for Lasers, Plasma and Radiation Physics, Laser Department and their performances tested in international comparisons during last four years at the Bureau International des Poids et Mesures (BIPM. 1993, 1995), at the Institute for Metrology `Gustavo Collonetti' (IMGC, 1994) and at the Institute for Scientific Instruments (ISI, 1996). Comparative results regarding frequency difference, repeatability and stability are presented. Results proved a good reproducibility of the performances during the time.