开展了入射角度对1064 nm纳秒激光诱导水下等离子体声波信号特性影响的研究,结果表明:当激光垂直入射时,激光诱导水下等离子体声波信号强度最大;随着入射角度增大,激光诱导水下等离子体声波信号强度逐渐减弱。由等离子体发光图像可知,激光诱导水下等离子体产生了多次聚焦。随着入射角度增大,水等离子体长度逐渐增加,等离子体腔体半径逐渐减小,且水等离子体发光辐射强度逐渐变弱。这是因为空气-水界面处的光学折射效应导致透镜的等效焦距变大,延长了聚焦透镜的瑞利长度,从而使激光诱导水下等离子体声信号的强度变弱。研究结果对激光水下声波探测以及激光通信具有重要意义。

Herein, the effect of the angle of incidence on the characteristics of underwater plasma acoustic wave signals induced by 1064-nm nanosecond laser was studied. Result shows that when the laser is incident perpendicularly, the intensity of the laser-induced underwater plasma acoustic wave signal was the strongest. With the angle of incidence increasing, the intensity of the underwater plasma acoustic wave signal gradually decreased. Based on the plasma luminescent image, the laser-induced underwater plasma was found to exhibit multiple times of focusing. As the angle of incidence increased, the length of the underwater plasma gradually became longer, the radius of the plasma chamber gradually became smaller, and the luminescence intensity of the underwater plasma became weaker. Because of the optical refractive effect on the air-water surface, the equivalent focal length of the lens became larger and the Rayleigh length of the focusing lens was extended, thereby reducing the intensity of the laser-induced underwater plasma acoustic wave signal. The research results obtained herein have important significance in fields of laser underwater acoustic wave detection and laser communication.