Measurements of optical frequency ratios using a compensated field sigmameter

Optical frequency ratios have been measured in the range from 576 to 633 nm at 10/sup -10/ relative accuracy level using a two-way-compensated field Michelson-type interferometer. The light sources consisted of He-Ne lasers and CW tunable dye lasers locked on the frequencies of hyperfine components of well-known molecular iodine lines. The instrumentation and measurement procedure are described. The accuracy of the measurements is shown to be approximately=8*10/sup -11/. Correction for a linear deviation from chromaticity is discussed.<>