A far infrared interferometric spectrometer with a special electronic computer

Working resolution of 0.010 cm(-1) between 20 cm(-1) and 1200 cm(-1) by a Fourier spectrometer

The original double-beam Michelson-type Fourier spectrometer at the University of Oulu has been partly modified so that a maximum resolution of slightly better than 0.010 cm(-1) between 20 cm(-1) and 1200 cm(-1) can be obtained. The resolution is determined as a halfwidth of an observed line. The accuracy of the line position is 0.0005 cm(-1) in favorable conditions. The Fourier spectrometer is connected on-line to a minicomputer, in order to make the fast Fourier transforms of interferograms of up to 10(6) sampling points. The maximum optical path difference of the interferometer is about 1.5 m, giving a maximum theoretical resolution of 0.004 cm(-1).

Double-beam high resolution Fourier spectrometer for the far infrared

The construction and the performance of a double-beam Michelson-type Fourier spectrometer are described. The instrument covers a wavenumber range from 10 cm(-1) to 450 cm(-1) with a maximum resolution of 0.025 cm(-1) and an accuracy of frequency within +/-0.001 cm(-1). The optical path difference is measured by means of an He-Ne gas laser. To illustrate the general performance of the instrument, the pure rotational spectra of H(2)O and CO have been recorded.