Wavemeter improvements for laser diode calibration

This paper shows the progress made in the wavemeter developed to give traceability to the wavelength of lasers and ECDLs (External Cavity Laser Diode). The improvements are: duplication of the optical path of the laser beams due to a double pass through the interferometer arms, the electronic fringe counter, the measurement of the refractive index of air and the uncertainty calculations of the wavelength for the case of lasers with frequencies that differs more than 10 THz from laser reference. The new measurements improve the previous results.