Two-dimensional angular optical scattering patterns as droplets evolve into clusters.

Remarkable changes in the two-dimensional angular optical scattering (TAOS) pattern are observed when an acoustically levitated water droplet with inclusions evolves into a dry aggregate. The emergence of polystyrene latex sphere inclusions near the droplet surface has a clear effect on the TAOS. A speckle pattern in the TAOS replaces the continuous contours associated with Mie scattering from a smooth droplet. Once the contours break up, this speckle pattern persists as the levitated droplet evaporates, making the transition from a droplet with inclusions to a dried aggregate. The initial emergence of the speckle pattern is observed for an inclusion volume fraction near 8%.