Perkin-Elmer MultiScope System, User Reference, Page: 113 / 142

Applications
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Specular Reflectance
Specular reflectance is reflection in one direction (Figure 34). This is the type of
reflection that occurs from a smooth, polished surface.
Absorption information cannot be obtained directly from a specular reflectance
spectrum of a dielectric material, because the reflectance spectrum is governed by
dispersion in the refractive index. However, you can use the Kramers-Kronig
integration to calculate the absorbance spectrum from the specular reflectance
spectrum. This integration is performed by the KK command in the Model 1600 and
Spectrum BX software and the Spectrum software.
Figure 34 shows the specular reflectance spectrum of a PMMA plate and
the absorption spectrum computed from it with the KK command.
Collected with an MultiScope System Microscope and a Spectrum RX with
MCT detector.
The greatest limitation to this method is the presence of an interfering diffuse
reflection signal. This occurs when the sample surface is not perfectly smooth. The
Kramers-Kronig integration is not appropriate for spectra from such samples.