The real and imaginary parts of the complex dielectric function were measured by the spectroscopic ellipsometric method in the near-infrared region to study the optical properties of granular FeAg films. On the basis of the Drude model, the purity of Ag films can be optically evaluated. The dependence of the reciprocal relaxation time gamma on the Fe concentration of FeAg films was studied, while other conditions were fixed. It was found that gamma is linear with the Fe concentration x in the 0 < x < 23.5% range. The effective-medium-approximation model was used to analyze the dielectric function of the granular FeAg films. (C) 2003 Elsevier B.V. All rights reserved.