MNL-1007 REV A
6
Fourier Transform Infrared (FT-IR) Spectroscopy
The core of any FT-IR spectrometer is a two-beam optical interferometer named the Michelson interferometer. The basic block
diagram of a Michelson interferometer’s discrete components is s
hown below.
A beamsplitter splits the incident beam into two paths: one of the beams is reflected by a moving mirror, and the other is used as a
reference when reflected by a fixed mirror. The moving mirror controls the Optical Path Difference (
OPD
) between the two reflected
beams, which interfere to produce a pattern that corresponds to the spectral content of the input light. The latter is captured by the
single photodetector generating an interferogram. The spectrum of the input light is directly generated by applying a Fourier
Transform to the interferogram.