激光声源特性研究及海洋应用

Laser-acoustic source characteristic and its application in ocean

激光声作为水下声源的一种新的激发方法,具有高声强、窄脉冲、宽频谱等优点。基于激光声激发的线性及非线性理论,建立了激光声信号特性的初步模型,研究了激光在水中激发声波的特性,研究表明:在热膨胀激发状态,增大激光光强可以提高激光声的转换效率;光强大于击穿阈值后,激光声的激发机制为非线性的光击穿机制。激光声具有的高距离分辨能力和海洋抗干扰能力,对水下目标探测、空载平台等领域有着较广的应用前景。

As a new method to generate underwater wave, laser-acoustics has a variety of commercial and oceanographic applications due to its merits such as high acoustic intensity, spike pulse and wide frequency spectrum. The primary model for laser-acoustic signal characteristic was established according to the linear and nonlinear theories of the laser-acoustic pulse. The characteristic that the laser may create acoustic wave in water was investigated. The research indicates that the increase of laser intensity can improve the laser-acoustic conversion efficiency in the state of the thermal expansion excitation, and when the intensity is higher than the breakdown threshold, the excitation mechanism of the laser-acoustics becomes nonlinear light breakdown mechanism. The laser-acoustics features high distance resolution and antiinterference. It has a great application prospect in underwater and airborne target detection.