Measurement of the speed of light

Blaney, T. G.; Bradley, C. C.; Edwards, G. J.; Jolliffe, B. W.; Knight, D. J. E.; Rowley, W. R. C.; Shotton, K. C.; Woods, P. T.

doi:10.1038/251046a0

Cited by 33 publications

(12 citation statements)

References 5 publications

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“…This, in turn, resulted in a dramatically improved value for the speed of light [41]. The measurements were confirmed by a group at the National Physical Laboratory (NPL), Teddington, U.K. [42]. The 3.39-m He-Ne laser is a convenient source with enormous gain which can be used with CH (a symmetric molecule) to provide good accuracy.…”

Section: A Historical Review Of Frequency Measurements Using Harmonimentioning

confidence: 97%

Optical frequency combs: From frequency metrology to optical phase control

Schnatz

Hollberg

2003

IEEE J. Select. Topics Quantum Electron.

165

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The merging of continuous wave laser-based precision optical-frequency metrology with mode-locked ultrafast lasers has led to precision control of the visible and near-infrared frequency spectrum produced by mode-locked lasers. Such a phase-controlled mode-locked laser forms the foundation of a "femtosecond optical-frequency comb generator" with a regular comb of sharp lines with well-defined frequencies. For a comb with sufficiently broad bandwidth, it is now straightforward to determine the absolute frequencies of all of the comb lines. This ability has revolutionized optical-frequency metrology, synthesis, and optical atomic clocks. Precision femtosecond optical-frequency combs also have a major impact on time-domain applications, including carrier-envelope phase stabilization, synthesis of a single pulse from two independent lasers, nonlinear spectroscopy, and passive amplifiers based on empty external optical cavities. The authors first review the frequency-domain description of a mode-locked laser and the connection between the carrier-envelope phase and the frequency spectrum to provide a basis for understanding how the absolute frequencies can be determined and controlled. Using this understanding, applications in optical-frequency metrology and synthesis and optical atomic clocks are discussed. This is followed by discussions of time-domain experiments.

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Section: A Historical Review Of Frequency Measurements Using Harmonimentioning

confidence: 97%

Optical frequency combs: From frequency metrology to optical phase control

Schnatz

Hollberg

2003

IEEE J. Select. Topics Quantum Electron.

165

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“…We have reported the progress of this whole experiment (Bradley et at. 1972 a, 6 ) ,and the result was announced in a letter (Blaney et al 1974).…”

Section: Introductionthe Speed Of Lightmentioning

confidence: 98%

Measurement of the speed of light I. Introduction and frequency measurement of a carbon dioxide laser

Blaney

Bradley

Edwards

et al. 1977

Proc. R. Soc. Lond. A

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This, and part II following, describe a determination of the speed of light made by measuring the frequency and wavelength of radiation from a CO 2 laser. This laser was operated on the 9.3 μm R(12) transition, and stabilized by reference to fluorescence in an external CO 2 absorption cell. The laser frequency was measured via a sequence of harmonic-mixing stages involving the HCN and H 2 O lasers as transfer oscillators, and was found to be 32 176 079 482 ± 14 kHz ( ± 4.2 parts in 10 10 ). A correction to this value of — 10 kHz is necessary to obtain the centre frequency of the CO 2 reference transition. The wavelength measurements and value of c are described in part II.

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“…separate measurements of the wavelength and frequency for a helium-neon laser stabilized to an absorption line in methane and obtained for the speed of light c = 299,792,457.4 + 1.1 Im/sec (0.004 ppm) Later, and independently, scientists at the National Physical Laboratory in Teddington, England, reported(21,22) measurements of the frequency and wavelength for a line in a carbon dioxide laser stabilized to an absorption line in carbon dioxide uncertainty of +4 x 10-9 resulting from uncertainties in realizing the 86Kr definition of the meter. Measurements carried out since then have confirmed the appropriateness of this value for the speed of light.…”

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confidence: 99%

Precision Measurements and Fundamental Constants

Pipkin

Ritter

1983

Science

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Recent developments in the techniques for making precision measurements and their use in the determination of the fundamental constants are reviewed. Particularly noteworthy developments are clocks with high stability, the proposed redefinition of the meter in terms of the standard for time, and the increased precision with which electrical standards can be maintained. The relevance of precision measurements to tests of general relativity is briefly discussed.

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Measurement of the speed of light

Cited by 33 publications

References 5 publications

Optical frequency combs: From frequency metrology to optical phase control

Optical frequency combs: From frequency metrology to optical phase control

Measurement of the speed of light I. Introduction and frequency measurement of a carbon dioxide laser

Precision Measurements and Fundamental Constants

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