Spectroscopic ellipsometry (SE) was applied to study the optical inhomogeneity of TiO2 films deposited by the technique of ion-beam assisted e-beam evaporation. A three-sub-layer model of ellipsometry analysis can successfully simulate the structure variation of TiO2 films, which consists of a dense amorphous layer near the substrate, a crystal columnar layer, and a very thin roughness layer on top. Such a theoretical model is further confirmed by microscopic observations with SEM, TEM, and AFM. The structure variation of TiO2 films is related to the increase of chamber temperature during the e-beam evaporation process. Annealing evolution of as-deposited TiO2 films in atmospheric environment at elevated temperatures of 150 and 250 degreesC was also investigated. The ellipsometry analysis shows that the total film thickness of TiO2 film increases with the annealing time at both temperatures. A more detailed analysis further reveals that thickness of the top sub-layer increased; whereas the region of the bottom amorphous sub-layer shrunk when the film was annealed at 250 degreesC. (C) 2004 Elsevier B.V. All rights reserved.