Photophoretic trampoline - Interaction of single airborne absorbing droplets with light

TL;DR

This paper demonstrates the manipulation of airborne absorbing liquid droplets using photophoretic forces, showing they can bounce off high-intensity light sheets and their trajectories can be controlled by light field variations.

Contribution

It introduces a novel method for light-induced manipulation of liquid droplets in air, extending photophoretic techniques to liquids for the first time.

Findings

Droplets follow quasi-ballistic trajectories after bouncing.

Rebound intensities are estimated and controllable.

Droplet paths can be altered by changing the light field.

Abstract

We present the light-induced manipulation of absorbing liquid droplets in air. Ink droplets from a printer cartridge are used to demonstrate that absorbing liquids - just like their solid counterparts - can interact with regions of high light intensity due to the photophoretic force. It is shown that droplets follow a quasi-ballistic trajectory after bouncing off a high intensity light sheet. We estimate the intensities necessary for this rebound of airborne droplets and change the droplet trajectories through a variation of the manipulating light field.