Reflectance phase-shift dispersion relation

Abstract

The dispersion (Kramers-Kronig) relation, used for calculating the phase of the reflectance of light between two media, is shown to require an additional term in certain cases of physical importance both at normal and oblique incidence; although not in the case usually discussed, i.e., when reflection is at normal incidence and the first medium is a vacuum. The type of term required is discussed and an example of a calculation given.