Axisymmetric stress field around a laser-induced bubble

We measure the spatiotemporal stress field around a laser-induced bubble by using a photoelastic method. Stress measurements using Particle Image Velocimetry are difficult to calculate the stress due to the inability to track particles near the bubble. The photoelastic method estimates the applied stress from the anisotropic change in the refractive index (birefringence) in the material and allows us to measure the stress field. In the experiment, a laser-induced bubble was generated in a fluid with water and nano-rod crystals, and photographed with a high-speed polarization camera. By applying a reconstruction method that assumes an axisymmetric field (Yokoyama et al., Opt. Lasers Eng., 2024, Ichihara et al., Exp. Fluids, 2022) and a stress-optic law, a three-dimensional stress field was obtained from the photographed images. The results were compared with the theoretical stress distribution around the bubble. The proposed method can be used to measure the shear stress generated when a bubble collapses near a wall or interface.