Dear All, I am trying to calculate the dielectric function of a thin silicon film from the real and imaginary values of the refractive index, which I have for wavelengths between 300 and 900 nm. If I have the n and k values (real and imaginary components of the refractive index), could anyone advise me as to how excactly to calculate the dielectric function from these values? Am I correct in thinking the formulae shown under the 'Relation to dielectric constant' section in the following link are the right formulae to use? http://en.wikipedia.org/wiki/Refractive_index Any advice would be greatly appreciated. Thanks.