Calibration of a Michelson-type laser wavemeter and evaluation of its accuracy

A calibration procedure for a scanning Michelson-type wavemeter is presented. The investigation includes calibration of the internal laser, which acts as a reference for the instrument using the optical heterodyne system in order to determine its absolute frequency and its frequency stability, which enables us to improve the measurement accuracy of the wavemeter. The resolving power of the instrument was also evaluated exploiting the strongest ten hyperfine components of the R(127) 11–5 transition of 127I2 emitted from an iodine-stabilised He–Ne laser. In our way to perform the previous tasks, we found the necessity to test the sensitivity and frequency uncertainty of the optical heterodyne system due to unequal powers of the mixed lasers. The obtained test results revealed insignificant consequences on the combined uncertainty for frequency measurements and verified that the wavemeter could be used for accurate wavelength measurements for the laser sources in the wavelength range 600–1800 nm with an accuracy of ±0.2 pm.