An Experimental Study on Micro-Bubble Generation by Laser-Induced Breakdown in Water

Abstract

This paper reports a detailed experimental investigation of bubbles with various diameters generated by laser-induced breakdown in water, which is an important issue in the field of laser medical care. The bubbles were generated by a pulsed Nd:YAG laser at 266-1064 nm, and the sizes of the bubbles were measured by a CCD camera. A time-resolved measurement with a gated ICCD camera revealed the process of bubble formation after laser breakdown. We were able to achieve manipulation of single bubble generation with desired bubble diameter ranging from 10 to 200 µm. The bubble size could be stably controlled as a function of the injected laser energy into water, which varied between 0.5 mJ and 12 mJ. More interestingly, the injected energy can form either a single bubble or multiple bubbles, with an energy more than 8 mJ, probably due to excess heat injection into the water. These results show the potential for generating nano-bubbles or micro-bubbles of arbitrary size.