Knowledge Bank

In order to facilitate spectroscopy using infrared diode lasers as sources, we have constructed a wavelength meter which readily allows us to determine the wavenumber of a laser line to an accuracy of $0.1cm-1$. This accuracy makes correspondence with reference spectra much easier. The meter is essentially a Michelson interferometer similar to that reported $previously1$, but its structure has been simplified by employing a liner encoder as a wavelength standard. Counting fringes in this way resulted in wavenumbers with the expected accuracy. We also showed by Fourier transformation of the fringe pattern that we might diagnose the multimode oscillation of a laser diode.