激光声信号的频谱特性

构建了激光声实验测量系统，利用脉冲激光聚焦击穿水介质产生声信号，由水听器将声信号转换成电信号并送入数字存储示波器。分析了激光声信号的时频域数学模型，实验研究了激光声信号的频域能量分布，以及激光器重复频率和激光声信号频谱特性的关系。结果表明:激光声信号能量主要集中在200 kHz内，其中100~200 kHz内的能量所占比例约50%。激光声信号的幅频响应极大值点可以受到激光器重复频率的控制。

Spectrum characteristics of laser-induced acoustic signals

The experimental system for laser-induced acoustic signals has been built. Acoustic signals are induced by pulsed laser focusing into water. A hydrophone is used to convert the acoustic signals into electric signals. The mathematic model for laser-induced acoustic signals in time and frequency domain has been analyzed. The energy distribution of the laser-induced acoustic signals in frequency domain has been studied. Characteristics of spectrums of acoustic signals produced by lasers in different repetition rates have been analyzed through experiments. The results are as follows: the laser-induced acoustic signals have most of their energy concentrated before 200 kHz, where half of that is between 100 kHz and 200 kHz. The maxima of laser-induced acoustic signals in frequency domain can be controlled by repetition rates of lasers.