Interferometric Wavelength Measurements through Post-Detection Signal Processing

Modern electronic signal processing techniques make it possible to use a conventional scanning Fabry-Perot interferometer for highly accurate measurement of (tunable) laser wavelengths. An experimental device is described in which the time intervals between resonances of an unknown wavelength are compared with those of a stabilized He-Ne reference laser by the use of highly accurate electronic timing devices. The accuracy is further enhanced through signal averaging over many scan periods. Accuracies approaching one part in 10
⁷
are expected to be readily achievable.