激光激发水中产生超声波的实验研究

采用压电陶瓷水听器研究了Nd：YAG脉冲激光激发水中产生瞬态超声波的特性，给出了声压信号随距离的变化关系。研究结果表明：用激光产生水下声波是完全可行的。当观测点与光击穿区的距离r远大于柱体长度时，垂直于光传播方向的激光瞬态超声波幅值与r成反比；当观测点与光击穿区的距离r很小时，垂直于光传播方向的声压幅值与产成反比。此外，当激光入射角度发生变化，超声脉冲的幅值也随之发生变化，其幅值在激光束垂直入射的时候最大。

Laser-Induced Plasma Ultrasound Waves in Water

The mechanism and/eature of ultrasound waves produced by Nd ： YAG pulsed laser in water are investigated in this paper. A PZT hydrophone is employed to receive the ultrasound wave signals. The relationship between ultrasound waves and the distance is obtained. It＇s quite clear that the laser-induced plasma ultrasound waves underwater are technically feasible. The experimental results show that when the distance between the observation point and breakdown region is far outweigh the length of podetium, the amplitude of the ultrasound waves across the direction of wave propagation is inversely proportional to the square of the distance; while the ultrasound waves across the direction of wave propagation is inversely proportional to the square of the distance when the distance between the observation point and breakdown region is very small. In addition, the amplitude of ultrasound waves vary with the laser incident angle, and it is the maximum when the incident direction of pulsed laser is perpendicular to the liquid