We present a terahertz time-domain experimental technique for the detection of scattering from porous media. The method for detection of the scattering enables one to make a decision when Fresnel or Kramers–Kronig (K-K) anal ysis can be applied for a porous medium. In this study the real refractive index of a tablet is calculated using the conventional K-K dispersion relation and also using a singly subtractive K-K relation, which are applied to the extinction coefficient obtained from the Beer–Lambert law. The advantage of the K-K analysis is that one gets estimates both for absolute refractive index and also dispersion of the porous tablet, whereas Fresnel analysis provides only the absolute value of the index.
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