Visualization of optical phenomena caused by multilayer films with complex refractive indices

This paper proposes a method for rendering objects coated with multilayer thin films. Multilayer thin films are widely utilized in industry for example, optical lenses, optical filters, and windowpanes, among others. Demand for visualization of the optical effects of multilayer films has therefore become great. To visualize optical properties of such films, we have developed a method for calculating composite reflectance and transmittance of the system of multilayer thin films, taking into consideration such factors as multiple reflection, interference and absorption of light inside the films. The proposed method is based on wave optics, and is able to accurately visualize the optical effects of multilayer films consisting of not only dielectric materials, but also metallic and semiconductive materials. Metallic and semiconductive materials are able to absorb light, and their refractive indices are expressed as complex values, Dielectric materials, on the other hand, do not absorb light, and the refractive indices are expressed as real values. Taking into consideration complex refractive indices, the proposed method can visualize optical phenomena caused by various kinds of multilayer thin films. The proposed method is implemented using a raytracer and optical properties of a SiO₂ film coating on a silicon base, and several kinds of multilayer films coating windowpanes or teapot are visualized to demonstrate the usefulness of the proposed method