Scattering of light by large bubbles: Coupling of geometrical and physical optics approximations

- The scattering of large bubbles is considered with a focus on the critical region.
- Effects of the tunneling phase are accounted in the geometrical approximation.
- Goos-Hänchen׳s shift and higher order rays are accounted in Marston׳s approximation.
- Most of the fine and coarse structures of the scattering diagrams are retrieved.

This paper analyzes various phenomena in modeling the light-scattering properties of large spherical bubbles in the context of geometrical and physical optics approximations. Among these phenomena are interference occurring between higher-order rays, the Goos-Hänchen shift, the tunneling phase and the weak caustic associated with the critical angle. When the phenomena are appropriately taken into account, they allow retrieval of most features of the scattering diagrams predicted by the Lorenz-Mie theory, offering new possibilities for the optical characterization of bubbly flows.