Interferometric cross check of two recommended wavelength standards at 633 nm and 657 nm

The wavelength standards at 633 nm and 657 nm in the visible part of the spectrum are characterized by most accurate frequency values obtained by frequency chain measurements. A cross check has been performed by an interferometric wavelength comparison and agreement was found within 3.8/spl middot/10/sup -11/ which demonstrates the applicability of both methods for a consistent wavelength scale.