Model for computing optical caustic partitions for the primary rainbow from tilted spheriodal drops.

Area of Science:

• Optics
• Fluid Dynamics
• Computational Physics

Background:

• Rainbows and caustics are optical phenomena resulting from light interacting with water droplets.
• Understanding these phenomena is crucial for interpreting light scattering and atmospheric optics.
• Oblate spheroidal drops, common in atmospheric conditions, present complex optical behaviors.

Purpose of the Study:

• To develop a computational model for salient optical caustic partitions in the primary rainbow of oblate spheroidal drops.
• To investigate the differences in optical caustic structures between tilted and aligned (untilted) drops.
• To explore the potential applications of caustic properties in drop characterization.

Main Methods:

• A model was developed to compute the boundary limits of outgoing rays from oblate spheroidal drops.
• Optical caustic structures, including rainbow and hyperbolic umbilic fringes, were calculated for various drop orientations.
• The curvature of rainbow fringes and shifts in cusp caustics were analyzed.

Main Results:

• The study successfully computed optical caustic partitions for oblate spheroidal drops.
• Distinct differences in caustic structures were observed between tilted and aligned drop orientations.
• Key features like rainbow fringe curvature and cusp caustic shifts were quantified.

Conclusions:

• The proposed model accurately computes optical caustics for oblate spheroidal drops.
• The calculated caustic properties offer potential for precise drop measurements.
• The model's framework is adaptable for drops of arbitrary shapes and orientations, and for shaped beam illumination.