The Effects of Temporally Changing Sources on Fourier Transform Spectrometers

A Michelson Fourier Transform Spectrometer senses an object/material in the time domain, producing an interferogram. To produce a spectrum, the interferogram is Fourier transformed into the spectral domain. Unless filtering is applied to the interferogram, all the time changing (AC) components of the interferogram contribute to the resulting spectrum. Aperiodic signals are not easily removed from the interferogram and, when transformed, result in false spectral features. Possible sources of real-world aperiodic signals are discussed and their effects on the resulting transformed spectra are demonstrated. Mitigation and avoidance techniques for some of the more common real-world aperiodic signals are discussed.