介绍了激光多普勒振动计(LDV)用于水下声光通信的应用背景,阐述了激光多普勒振动计的工作原理和两种相干检测方式。采用零差的相干探测方式,设计并实现了一套光纤结构的激光多普勒振动计。为了证明系统能够应用于水下声光通信,进行了对水下声源发出的声波频率和强度的探测实验。通过对实验数据的分析得出：第一,系统能够检测出水下声源发出的声波频率,对7 kHz附近的10个声波频率的测量标准偏差小于8 Hz; 第二,系统探测信号强度与水下声源发声的声压级成指数关系,对于水下目标通信所用的3.5 kHz和7 kHz声波频段的最小探测能力分别达到146.2 dB和150.8 dB声压级。

This paper introduces the application background for developing an laser Doppler vibrometer (LDV) for underwater acoustic communication and expounds the principle of laser Doppler vibrometer and two coherent detection methods. Using the way of homodyne coherent detection, a fiber laser Doppler vibrometer is designed and completed. To prove the system can be used in underwater acousto-optic communications, with this system, the acoustic frequency and intensity of underwater sound source are detected. Through the analysis of experimental data, two conclusions are gotten: first, the system is able to detect the acoustic frequency of underwater sound source, the standard deviation of measuring ten acoustic frequencies near the frequency of 7 kHz is less than 8 Hz; second, the signal intensity of system detection is an exponential function of acoustic press level of underwater sound source. For the acoustic band of 3.5 kHz and 7 kHz used in underwater communications, the smallest sound press level of detection reached 146.2 dB and 150.8 dB respectively.