激光等离子体声信号特性

为了对激光等离子体声信号特性进行深入研究，构建了激光声实验系统。使用波长1.06 mNd:YAG 脉冲激光聚焦击穿水介质产生激光等离子体声信号，使用水听器对信号进行接收，通过高速摄像机对信号产生过程进行了记录。分析了激光等离子体声信号的时频域特征。从理论上研究了激光等离子体声信号的指向性和传输特性，并进行了实验验证。研究结果表明:激光等离子体声信号时域脉宽为15 s 左右，频带宽度为200 kHz，主频在70 kHz 左右。信号在不同传输角度上的幅度差异很小，按照近似1/r 的规律衰减，传输过程中主频逐渐减小。

Characteristics of laser-induced plasma acoustic signal

The experimental system for laser -induced acoustic signals had been built for research on characteristic of laser-induced plasma acoustic signals. Acoustic signals were produced by pulsed laser focusing into water. A hydrophone was used to receive the acoustic signals. A high speed camera was used to record the breakdown procession. Time and frequency domain of laser-induced plasma acoustic signals were studied. Its directivity and transmission characteristic were analyzed theoretically, and proven by experiment. The results are as follows: The pulse width of laser-induced plasma acoustic signals is about 20 s, its frequency width is 500 kHz and main frequency is 70 kHz. It transmits in all directions and decreases proportionally to 1/r, main frequency decreases as distance increases.