Stabilized lasers and precision measurements.

This article traces the development of stabilized lasers from the Massachusetts Institute of Technology passive-stabilization experiments of the early 1960's up through the current epoch of highly stabilized helium-neon and carbon dioxide and continuous wave dye lasers. The utility, present performance, and limitations of stabilized lasers as standards of length or frequency for precision measurements are discussed. Examples considered of laser applications to physical measurements of outstanding scientific interest include determination of the speed of light, redefinition of the meter, resolution of the photon recoil-induced spectral doubling, use of optical "Ramsey" interference fringes from ultrahigh-resolution spectroscopy, and two improved tests of special relativity.