ACTRIS Vocabulary
FTIR spectrometer
Instrument to measure the spectral light emission or absorption of a sample, here in the infrared spectral range. The light emitted by the sample, or passed through the sample from a polychromatic light source, is passed into a Michelson interferometer. The Michelson interferometer splits the light beam into 2 parts, where both parts are individually reflected, re-united, and the intensity of the united beam measured. The 2 parts of the light beam experience a difference in optical path length, where the optical path difference can be varied. By scanning through the optical path difference, various combinations of wavelengths are passed through the Michelson interferometer. The mathematical operation of converting the optical path difference scan into an emission / absorption spectrum is called Fourier transform.
Fourier Transform Infrared Spectrometer
experiment technique
light absorption spectrometer
reactive trace gas remote sensing