Frequency-Stabilized Laser for Measurement of Length

Abstract

Development of frequency-stabilized lasers in optical and infrared regions, measurements of their frequencies by harmonic generation and frequency mixing, and, their use for accurate determination of the velocity of light, have brought about the possibility of a radical change in the definition of the metre. In the near future, the metre may become linked with the second or with the hertz. However laboratory measurements of length will perhaps continue to be made in wavelengths of light.

The paper contains a brief review of the work on laser frequency stabilization and measurements of their frequencies and wavelengths, which led f o the possibility of re-definition of the metre. The work being done in the National Physical Laboratory on the development of frequency-stabilized lasers and laser metrology is also described.