Abstract: The optical properties of the granular Sn films coated with Al films are studied. The experimental results indicate that the Al coating strongly affects the optical properties of the granular Sn films, enhancing the spectrum selectivity of solar energy in the visible region and the reflectance near the IR region. The filling factor Q of granular Sn films obviously influences the optical properties of the films system. Based on the installed structure model and the Maxwell-Garnett theory, the reflective spectra are calculated. The calculated results agree with the experimental cnes. It is also found that the Al coated granular Sn films have various kinds of reflective colors, thus they may be used as decorative mirrors for many purposes.

Key words: granular films, filling factor, the films system for two layers