International comparisons of He-Ne lasers stabilized with¹²⁷I₂at   = 633 nm (July 1993 to September 1995). Part IV: Comparison of Western European lasers at   = 633 nm

Abstract

This paper reports the fourth 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 Comité Consultatif pour la Définition du Mètre (CCDM; now the Consultative Committee for Length, CCL) during the period July 1993 to September 1995. The results of this comparison, involving eleven lasers from eight countries and the BIPM, again meet the goals set by the CCDM in 1992 and adopted by the Comité International des Poids et Mesures (CIPM) the same year. The standard uncertainty of the frequency of the He-Ne laser stabilized on the saturated absorption of 127 I 2 at λ 633 nm is reduced to 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 BIPM4 laser with the parameters set to the values normally used in each laboratory; using the BIPM4 laser as a reference the results ranged from -15.4 kHz to 36.8 kHz. After checking and readjusting the values of all the parameters, the range was reduced to -8.6 kHz to 14.0 kHz. Under the latter conditions, the average frequency difference of the group of lasers, with respect to the BIPM4 laser, was 2.7 kHz with a standard uncertainty (1 ) of 8.1 kHz. The best relative frequency stabilities, with Allan standard deviations of about 5.5 parts in 10 12 and 4.6 parts in 10 13 , were observed with sampling times of 1 s and 100 s, respectively.

Absolute optical frequency measurements of iodine-stabilized He-Ne laser at 633 nm by using a femtosecond laser frequency comb

“…Here we present the results of absolute frequency measurements of laser CEM2 (Winters Electro-Optics, model WEO116) which is in operation since 1993 and which was among others compared with Bureau International des Poids et Mesures (BIPM) in 1994 [13] and 1995 [14]. The frequency of CEM2 was consistent with the other participating lasers in the comparison, i.e., within several kHz.…”

Effect of frequency modulation amplitude on Iodine stabilized He-Ne Laser, at λ ≈ 633nm

“…The effect of modulation amplitude on the d, e, f, g components of transition 11-5, R(127) of 127 I 2 was determined by (9,10,11) and tabulated in tables (2, 3 and 4). Where ∆f/fω is the modulation width factor, L is the slope of a linear fit to the data points and s the estimated standard uncertainty of one measurement.…”

Calibration of Displacement Laser Interferometer Systems for Industrial Metrology

“…The iodine-stabilized laser is mentioned as a primary standard in the earliest documents concerning the meter definition based on the speed of light from the BIPM (Bureau International des Poids et Mésures) [3]. Since then, several comparisons have been held (e.g., [9]) that led to the conclusion that the quoted uncertainty of this standard could be further reduced, as was established in [8,10]; this was reconfirmed more recently [11]. This is summarized in Table 1.…”