Abstract: The present research consists in characterizing the surface quality of polished optical glass (LF7) by ellipsometry and use of effective medium model. A correlation between effective roughness layer and ellipsometric measurements has been established as glass fraction f %. Ellipsometric parameters in dependence of polishing time have been measured and treated on the base of the theory of Maxwell-Garnett assuming an effective medium layer of effective thickness de and refractive index ne.