Polarization-based imaging of dynamic strain-induced during holmium laser ablation

The strain effected by holmium laser-induced cavitation bubbles in tissue phantom (PAA gel) was studied using a birefringence-based technique. A Q-switched Nd:YAG laser was used to image the straining of the gels while CCD camera captured the radiation transmitted through the gel. The cavitation bubbles within and at the surface of the gel localized straining of the gel both upon the bubbles' expansion and collapse. During bubble expansion, slight deformation of the surface occurred; during bubble collapse, however, tensile forces induced deformation on the surface on the order of 1 mm.