Internal caustic structure of illuminated liquid droplets

High-order interior caustics produced in scattering of a diagonally incident plane wave by a circular cylinder

“…Analytical equations for the shape of these caustics for an arbitrary location of the internal source were also derived by using the method employed in Appendix A of Ref. 15. Figure 7(d) shows a composite of the 1, 2, and 1 ϩ 2Ј interior caustics.…”

“…11,12 But when a point source is brought close to the sphere, the p ϭ 1 near-zone spherical aberration caustic splits into two branches and evolves into a far-zone rainbow. 13 The interior caustics of a sphere include the so-called p ϭ 1 Descartes ring, which is the extension of the spherical aberration cusp into the sphere, 14 and various cusp caustics and axial spike caustics [15][16][17] for p у 2. The p ϭ 1 Descartes ring, enhanced by morphologydependent resonances, has been observed at the surface of both water and methanol droplets by means of stimulated Raman scattering (SRS).…”

“…2 The full p ϭ 2 axial spike caustic has also been observed in a spherical globe filled with water into which a small amount of milk had been added. 15 For scattering by an oblate spheroidal particle with side-on incidence, the rainbow evolves into a higherdimensional optical caustic whose full structure unfolds as the spheroid refractive index and eccentricity are varied. The unfolding of this caustic for p ϭ 2 has been numerically and analytically explored by Nye,22,23 and the unfolding as a function of spheroid eccentricity has been experimentally studied by Marston and his co-workers for p ϭ 2, 24-27 p ϭ 3, 28 and p ϭ 6.…”

Optical caustics observed in light scattered by an oblate spheroid

“…For this θ i 0 interval, the horizontal radius of curvature R is now negative, corresponding to rays intersecting the exit plane in the horizontal direction as they converge toward an effective point source on the real caustic. There is also a virtual axial spike caustic [34] formed by the backprojection of the rays in all planes of incidence with the same deflection angle Θ 0 . These projections all cross the z axis at…”

Semiclassical scattering of an electric dipole source inside a spherical particle

“…27 Thus it is of interest to inquire whether the p ϭ 1 scattering resonance/total internal reflection rainbow of Fig. 12(b) at Ϸ 135°remains visible in I total ave (r, , ).…”