A zero-dispersion monochromator and two-beam output for UV Fourier transform absorption spectrometry

The motivation for using a zero-dispersion monochromator as a band-pass filter with a Fourier transform spectrometer is discussed, and the design of such an instrument is presented. Benefits in performance over commercial band-pass filters are demonstrated. In addition the advantages of using the second optical output of the spectrometer are discussed, particularly with respect to absorption spectroscopy when the signal from the second output can compensate for fluctuations and drift in the intensity of the background continuum source.