Experimental observation of immediate focus of underwater shock wave by using concave emitter induced by nano-pulsed laser
Experimental observation of immediate focus of underwater shock wave by using concave emitter induced by nano-pulsed laser
复制标题
纳米脉冲激光诱导凹面发射器水下冲击波即时聚焦实验观察
DOI：
10.1007/s12650-017-0422-x
复制
发表时间：
2017
影响因子：
1.7
通讯作者：
Hirahara Hiroyuki
中科院分区：
文献类型：
--
作者：
Hemel Rokhsan Ara;Hirahara Hiroyuki
摘要 采用阴影技术观察了单脉冲激光引起的水下微冲击波的传播。为了将微冲击波引入水中，使用涂有100纳米厚钛金属的平面和凹面玻璃设计了不同类型的冲击波发射器。实验在0至200GW/m2的低辐照强度范围内进行，通过金属膜的热弹性效应产生冲击波。在这项研究中，我们提出了一种使用凹面的立即聚焦技术。通过光学观察和压力测量证实了聚焦效果。使用阴影成像技术计算冲击波的速度和马赫数。结果表明，激光诱发的微冲击波在水中的传播速度大约低于声速。通过压力测量，证实凹面发射器产生的冲击波强度比平面发射器强1.5倍。焦点的有效面积由凹面的曲率半径和照射光束直径决定。图形摘要
AbstractPropagation of an underwater micro-shock wave induced by a single-pulsed laser was observed by the shadowgraph technique. To introduce the micro-shock wave into water, different types of shock wave emitters are designed using flat and concave glass coated with 100-nm-thick titanium metal. The experiment was carried out in low irradiation intensity range from 0 to 200 GW/m2, and the shock wave was produced by the thermo-elastic effect of the metal film. In this study, we proposed an immediate focusing technique using a concave surface. The focusing effect was confirmed by optical observation and pressure measurement. The velocity and Mach number of shock wave were calculated using a shadowgraph imaging technique. The result revealed that the laser-induced micro-shock wave propagated approximately at just under the sound of speed in water. From the pressure measurement, it was confirmed that the shock wave strength from the concave emitter was 1.5 times stronger than the flat one. The effective area of the focus was determined by the radius of curvature of the concave surface and the irradiation beam diameter.Graphical Abstract