A technique for the elimination of baseline variation is discussed and illustrated. The method involves ultra-low frequency filtering in the frequency domain (transform space) and is illustrated by applying it to several diode laser spectra of C2H6 (ethane). In the examples presented, the technique eliminates the effects of diode laser output energy variations as a particular mode is scanned. This technique may be especially valuable for diode laser spectroscopy where a multipass cell is used and where the cell cannot readily be removed from the beam to obtain a background scan. The technique should be applicable to baseline variation problems in general.
Ahmet K. Atakan, W. E. Blass, and D. E. Jennings, "Elimination of Baseline Variations from a Recorded Spectrum by Ultra-low Frequency Filtering," Appl. Spectrosc. 34, 369-372 (1980)