Speed of Light from Direct Frequency and Wavelength Measurements of the Methane-Stabilized Laser

  title={Speed of Light from Direct Frequency and Wavelength Measurements of the Methane-Stabilized Laser},
  author={Kenneth M. Evenson and Joseph S. Wells and F. Russell Petersen and B. L. Danielson and Gordon W. Day and Richard Lee Barger and John L. Hall},
  journal={Physical Review Letters},
The National Bureau of Standards has had a long history of interest in the speed of light, and no doubt this interest contributed to the measurement described here [1]. As early as 1907, Rosa and Dorsey [2] determined the speed of light from the ratio of the capacitance of a condenser as measured in electrostatic and electromagnetic units. Over the ensuing years NBS developed still other methods to improve upon the accuracy of this important physical constant. By the late 1960s, lasers… 

Figures from this paper

Laser wavelength measurements and the speed of light
Early determinations of the speed of light, based on astronomical observations or terrestrial time-of-flight experiments, were largely superseded in the 1940's by measurements of the frequency and
Laser frequency measurements, the speed of light, and the meter
The spectral characteristics of electromagnetic radiation are determined by either its vacuum wavelength or its frequency (and, of course, the speed of light is the product of the two). Before the
AbstractDuring the last few years several measurements of both the frequencies and wavelengths of laser radiations have been completed, from which values of the speed of light in vacuum, c, have been
Measurement of the speed of light II. Wavelength measurements and conclusion
Wavelength measurements have been carried out on the radiation at 9.3 pm from a stabilized CO2 laser. The wavelength in vacuum was determined as 9 317 246 348 femtometres (fm), with a standard error
Measurement of the speed of light I. Introduction and frequency measurement of a carbon dioxide laser
This, and part II following, describe a determination of the speed of light made by measuring the frequency and wavelength of radiation from a CO2 laser. This laser was operated on the 9.3 μm R(12)
Wavelength standards, optical frequency standards, and the velocity of light
He-Ne lasers, when stabilized to an absorption line of iodine (127I2 or 129I2), or of methane (CH4), give coherent radiations whose frequency can be maintained constant within about one part in 1012,
Wavelength ratio of stabilized laser radiation at 3.39 Mum and 0.633 Mum.
A servo controlled Michelson interferometer with a displacement of 3.8 m between the final positions of the movable mirror has been developed for precise laser wavelength comparisons. This instrument
Frequency Stabilization of the He-Ne Laser by Means of Saturated Absorption in Iodine
Hoping to develop a future primary standard of length to use for precision interferometric length measurement, a frequency-stabilized He-Ne laser has been made. The frequency of the 0.633ƒÊm output
Optical frequency/wavelength references
For more than 100 years, optical atomic/molecular frequency references have played important roles in science and technology, and provide standards enabling precision measurements. Frequency-stable


A new determination of the free-space velocity of electromagnetic waves
  • K. Froome
  • Geology
    Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences
  • 1958
The paper describes the determination of the free-space phase velocity of electromagnetic waves in vacuo by means of a millimetre-wave interferometer capable of high precision. As already