Investigation of microplasma produced in physiological saline by a high-power YAG laser

Microplasma and shock waves produced by a Q-switched YAG pulse laser worked near the optical breakdown threshold of physiological saline are investigated by using optical shadowing exploring method. A series of optical shadowgraphs of microplasma and shock waves versus the incident laser energy and the delay time is obtained. The mechanical action of shock waves is discussed.