Wavelength references for interferometry in air

摘要

Cavity-mode wavelengths in air are determined by measuring a laser's frequency while it is locked to the mode in vacuum during a calibration step and subsequently correcting the mode wavelength for atmospheric pressure compression, temperature difference, and material aging. Using a Zerodur ring cavity, we demonstrate a repeatability of +-2 X 10~(-8) (3sigma), with the wavelength accuracy limited to +-4 X 10~(-8) by knowledge of the absolute helium gas temperature during the pressure calibration. Mirror cleaning perturbed the mode frequency by less than (DELTA)v/v approx 3 X 10~(-9), limited by temperature correction residuals.