Note:
Theoretically $f(R_{\mathrm{\infty }})$ equals the ratio of the linear decadic absorption coefficient to the scattering coefficient. Under the assumptions of the Kubelka Munk theory, if the scattering coefficient at a given wavenumber is a constant for a given set of samples, $f(R_{\mathrm{\infty }})$ is directly proportional to the product of the absorption coefficient and concentration of each component of a mixture, analogous to the behaviour of absorbance under Beer’s law.