Inhomogeneities in Y2O3 and CeO2 optical films

The inhomogeneities in optical films, caused by the onset of nucleation and growth of the film adjacent to amorphous glass surface, are one among numerous sources of errors in precise optical coatings production. In some recent papers it was shown that the model of the multilayer system containing a certain number of films could analyze ZrO2 films. We have used a similar modeling approach to analyze some other optical materials such as Y2O3 and CeO2. Films have been produced using a standard reactive evaporation technique. Following the measurement results, obtained by zero angle transmission and variable angle spectroscopic ellipsometry, reverse design of the monolayer with its sub-layers has been performed. A very good fit of the experimental data with the reverse designed multilayers has been obtained, showing that it is possible to find a fine substructure of analyzed films. The obtained stacks can be used then in the multilayer design process as replacement for a single film adjacent to the substrate.