Principles, Description, And Functions Of The Iraffinity-1; Principle And Construction - Shimadzu IRAffinity-1 Instruction Manual

Chapter 1 Principles, Description, and Functions of the IRAffinity-1
1.1

Principle and Construction

The Fourier Transform InfraRed spectrophotometer measures an infrared spectrum by Fourier-transform of an
interferogram.
The Physics of Fourier Transform Spectrophotometry
An FTIR uses one of several optical systems; the IRAffinity-1 relies on a Michelson interferometer
After passing through the aperture, light is turned into a parallel beam by the collimator mirror and enters the
beam splitter. A germanium film, deposited on a potassium bromide substrate via evaporation, comprises the
beam splitter; it splits the single beam into two, reflecting one to the fixed mirror and transmitting the other to the
moving mirror. Both mirrors reflect their beams back to the beam splitter; part of each returning beam is
reflected and transmitted. The transmitted light from the fixed mirror and the reflected light from the moving
mirror recombine and interfere with each other as they travel towards the collecting mirror. The interference is
either constructive or destructive.
IRAffinity-1
1-2
Moving mirror
Detector
Fig. 1.1 Michelson Interferometer
Fixed mirror
Beam
Aperture
splitter
Light
source
(Fig. 1.1).
Collimator mirror