A NEW ABSOLUTE FREQUENCY REFERENCE GRID IN THE 28 THz RANGE

CO2laser stabilized on narrow saturated absorption resonances of CO2, improved absolute frequency measurements

“…The results of the measurements are summarized in Table 1. These m easurem ents are obtained relativ e to the position of OsO4 markers and in the second colum n we report the frequency of these OsO4 lines obtained from [6] and [14] and updated with more recent measurements [7,15,16]. The typical uncertainties of our measurements are from 50 Hz to 200 Hz.…”

“…However, because of the very weak contrast of the signal, it was not possible to stabiliz e the laser frequency on such resonances, and their frequencies were measured by recording alternately the spectra of the CO2 laser and OsO4 lines. Only the P(12), P (14) and R(10) lines were compared with the OsO4 frequency grid. In 1995, we developed a new stabiliz ation schem e for our CO2 lasers based on the detection of strong OsO4 absorption lines detected in transmission of a Fabry-P Â erot cavity [12].…”

High-accuracy Capabilities of an OsO4Molecular-beam Frequency Standard

“…The flux of molecules excited to the upper level via a Ramsey interaction can then be expressed through (6,7,8) in the following comprehensive form: (9) Expression ( 9) is tabulated in Fig. 6 versus r,/eo in the case of the P(39) A; 1 9 2 0 s 0 4 line for different power coefficients x2, having assumed 6 = 112 and…”

“…In the metrological field of optical frequency synthesis the 10 pm region is a common step for high-precision frequency measurements of the HeNe laser emissions at 3.39 pm, stabilized on the v 3 P (7) F$' ) absorption line of CH, [4], and at 0.633 pm stabilized on the 11-5R (127) absorption line of [ 5 ] , leading to the precise evaluation of the speed of light and successively to the re-definition of the metre [6]. Moreover, the development of the CO, frequency standard stabilized on the OsO, vibrational absorptions [7] has originated a reference grid [8] with a precision of the order of 1 kHz at 30 THz with a range of 1.2 THz; the extension of the above grid has been recently demonstrated [9] by use of RuO,.…”