Measurement error in frequency measured using wavelength meter due to residual moisture in interferometer and a simple method to avoid it

Abstract

We have experimentally evaluated the accuracy of the frequency measured using a commonly used wavelength meter in the near-infrared region, which was calibrated in the visible region. An error of approximately 50 MHz was observed in the frequency measurement using the wavelength meter in the near-infrared region although the accuracy specified in the catalogue was 20 MHz. This error was attributable to residual moisture inside the Fizeau interferometer of the wavelength meter. A simple method to avoid the error is proposed.