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为了了解激光声在液体中的传输特性,理论分析了激光声的传输特性,并采用高速照相机、光纤MEMS水听器对激光声进行了实验研究,利用小波变换对采集的不同位置上的激光声信号各级频谱特性进行了分析。结果表明:激光声属于一种脉动球源,激光声信号传输过程中幅度与距离成反比关系;激光声的分析频带内存在明显的优势频率,峰值频率稳定在3.1 kHz,带宽稳定在3 kHz;低频信号的能量占总能量的70%以上,高频部分主要是噪声;从功率谱波形分析看,低频信号的强度幅值随时间、距离变化衰减较慢,而高频噪声随时间、距离变换衰减较快。
In order to understand the transmission characteristics of laser sound in liquid, the transmission characteristics of laser sound were theoretically analyzed. The laser sound was experimentally studied by using high-speed camera and optical fiber MEMS hydrophone. The laser sound at different positions collected by wavelet transform The signal spectrum characteristics were analyzed. The results show that the laser sound belongs to a pulsating ball source. The amplitude and distance of the laser acoustic signal are inversely proportional to each other. The dominant frequency of the laser acoustic analysis is 3.1 kHz and the bandwidth is stable at 3 kHz. The energy of low-frequency signal accounts for more than 70% of the total energy and the high-frequency part is mainly noise. From the analysis of power spectrum waveform, the amplitude of low frequency signal attenuates slowly with time and distance, while the high frequency noise changes with time and distance Decay faster.