Elastic Waves Generated by Laser Induced Bubbles in Soft Solids

Abstract

We experimentally investigate the generation and propagation of elastic waves in gelatin occurring during the collapse of laser induced bubbles. Sub-millimeter sized bubbles are generated with a pulsed 6ns laser within the tissue mimicking material. The stress fields and wave propagation is visualized with elastography, a method where the polarity of a polarized light is altered by the state of stress of the medium. High-speed photography captures the fast dynamics of the bubbles and is used to describe the succession of events leading to the wave emission. 4 configurations of bubble collapse are studied; spherical and non-spherical collapses in the bulk, collapse near a wall and collapse near a free surface.