International comparisons of He-Ne lasers stabilized with¹²⁷I₂at   = 633 nm (September 1999). Part IX: Comparison of BEV (Austria), CMI (Czech Republic), GUM (Poland), OMH (Hungary), NIPLPR (Romania) and BIPM lasers at   = 633 nm

Abstract

This paper reports the ninth set of results of a series of grouped laser comparisons from national laboratories undertaken by the Bureau International des Poids et Mesures (BIPM) at the request of the Consultative Committee for Length (CCL), formerly the Consultative Committee for the Definition of the Metre (CCDM), for the periods July 1993 to September 1995 and March 1997 to March 2001. As with the previous eight comparisons, this one is expected to be listed as a key comparison in the context of the ongoing BIPM.L-K10 series.The results of this comparison, involving six lasers from five European countries and the BIPM, meet the goals set by the CCDM in 1992 and in 1997 and adopted by the International Committee for Weights and Measures (CIPM) the same year. The standard uncertainty (1 σ) of the frequency of the He-Ne laser stabilized on the saturated absorption of 127I2 at λ = 633 nm is reduced to a level of 12 kHz (2.5 parts in 1011) when the lasers compared meet the recommended values of the parameters.The lasers were first compared with the BIPMP3 laser, with all the lasers set to the parameter values normally used in each laboratory; the results then ranged from -97.6 kHz to +30.4 kHz. After checking and correcting when possible the values of all the parameters, the range was reduced to -16.4 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 5.6 kHz with a standard uncertainty (1 σ) of 9.9 kHz. The best relative frequency stabilities, with Allan standard deviations of about 9.7 × 10-12, 6.0 × 10-13 and 2.0 × 10-13, were observed with sampling times of 1 s, 100 s and 1000 s, respectively. The overall best values were 1.0 × 10-13 and 9.0 × 10-14 for sampling times of 3000 s and 12800 s, respectively.

International comparisons of He-Ne lasers stabilized with127I2at 633 nm (July 2000). Part X: Comparison of INMETRO (Brazil), INTI (Argentina), NRC-INMS (Canada), CENAM (Mexico), and BIPM lasers at 633 nm

“…This is the tenth in a series of reports describing the results obtained during an extensive programme of laser comparisons carried out over the period July 1993 to March 2001 [1][2][3][4][5][6][7][8][9][10].…”

The Optical Frequency Standards for the Realization of the Meter

“…The very first formal comparison termed BIPM.L‐K10 was performed from 1989 till 2000 . The frequency standards compared were iodine‐stabilized He–Ne lasers (see Section 4.3 below) operated by 46 NMIs all over the world.…”

International comparison of He-Ne lasers stabilized with127I2at 633 nm between the SMU (Slovakia) and the BEV (Austria)

“…The modulation width was determined before each measurement and set to the value recommended by the CIPM, (6.0 ± 0.3) MHz peak-to-peak [2]. It was measured by a technique developed at the Czech Institute of Metrology [8] that has already been used successfully in two other international comparisons [3,9].…”

“…The aim of this comparison was to check whether the frequencies of all three lasers are within the range of ±12 kHz (2.5 10 -11 relative) recommended by the CIPM [2]. The BEV laser was used as the reference laser because a few months earlier the frequency of the national wavelength standard of Austria, BEV1, had been measured in the framework of EUROMET Project 498, held at the BEV in September 1999 with the BIPM as pilot laboratory [3].…”