In the context of complex refractive index, is it possible to apply the Kramer-Kronig relation in the region of normal dispersion ? What I want to do is the following. I can measure real part of complex refractive index of a material, n in the limited range of 200-1000 nm wavelength where refractive index shows normal dispersion behaviour namely Cauchy behaviour. Now, by applying Kramer-Kronig relation, is it possible to calculate the imaginary part of complex refractive in the same region. If yes, please indicate how?