一种基于光学的水表面微波跨介质探测方法

Water surface capillary wave detection method based on optical devices

水下声信号的传播和探测研究主要集中在散射、反射和传播损失等方面,而对其在水面引起的波动关注较少。本文在理论上推导了在水下平面波入射在水-空气界面激励的水表面微波与声源强度和频率的关系。这种水表面微波的振幅在纳米级别,振动频率和水下平面波的频率相同,在水-空气界面的扩散距离则随频率的升高而强烈衰减。基于水表面微波的特性,结合激光探测的工作原理,设计了一套跨介质水下目标检测系统。并为该系统可能受到的低频海浪噪声干扰和反射干扰提供了应对方式。仿真结果表明:该系统分辨率高,具有隐蔽性、易于维护性、无接触性等特点,对低频声源的检测效果较好。该方法结合了声波在水中和光波在空气中传播各自的优点,有望成为水下目标检测的一种新手段。

Studies of long-range propagation or detection of underwater sound waves mainly focus on scattering,re-flection,and transmission loss.Under these conditions,the water surface is often considered rigid such that the ti-ny capillary waves induced at the water-air interface are often neglected.In this study,water-air interface morphol-ogy is analyzed when an underwater far-field acoustic wave reaches the water surface.This water surface wave vi-brates at the nano level with the same frequency as the underwater incident sound wave,which decreases exponen-tially.Moreover,the maximum distance a water surface wave can travel decreases rapidly when its frequency in-creases.Based on the abovementioned discussion and the working principle of laser detection,a crossmedia under-water target detection system is designed,and a technical solution is provided to suppress interference from the low-frequency noise of ocean waves and reflections.Simulation reveals that this system has good resolution.Moreover,the devices used in this system are concealed,contactless,and easily maintained,having a good effect on the de-tection of low-frequency sound sources.By combining the advantages of a light wave traveling in air and a sound wave traveling in water,this method can be a new promising means for underwater target detection.