This animated tutorial explains the principles behind the operation of the interferometer in an FTIR spectrometer. The tutorial examples start from a single wavelength so that students can begin with an easier example. After that, the examples explain the superposition of multiple wavelengths. Finally, the tutorial explains the connection between an interferogram and a frequency domain spectrum.
The animated explanation is available here . (Provided by the Chemistry Department at the College of Wooster. The webpage opens with a picture of a building at the College of Wooster. Look in the lower left hand corner to find the first page in the animated tutorial.)