Page 82 - Tandem Techniques
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The Simple Grating Infrared Spectrometer
A diagram of the grating IR spectrometer is shown in Figure 2.10. Light from the IR source is reflected
from a mirror, through the reference cell, through an attenuator system and onto a second mirror. The
beam is attenuated by imposing a device that removes a continuous but controllable fraction of the light
from the reference beam. The attenuator usually takes the form of a comb, the teeth of which are cut so
that the amount of light attenuated is linearly related to the lateral movement of the comb through the
beam. After passing through the attenuator to the second mirror, the attenuated light passes through a
chopper to a grating, where light of a specific wavelength is selected and passes to an IR sensor.
Figure 2.10
The Simple Grating IR Spectrometer
A second beam of light from the source is reflected through the sample cell by a plane mirror and then,
by means of another mirror, also passes through the chopper to the grating and then to the IR sensor.
