Three-dimensional optical billiard chaotic scattering

We report on the first experimental measurements taken from an easily studied, visually remarkable chaotic scattering system that we call an optical billiard. In particular, we measure the fractal dimension of the basin boundaries generated by the reflection of light from various configurations of polished, reflecting spheres. We find that our experimentally determined fractal dimension values agree well with the values we find from simulations. We also find that depending on the configuration of the spheres, the boundary can be either a nowhere-differentiable surface or else can possess the topological Wada property whereby any basin boundary point is simultaneously on the boundary of four distinct basins. Other configurations yielding other topologies of the chaotic scattering set are suggested for future study.