液体中激光束对热弹声源影响的研究

Study on effect of laser beam on thermoplastic ultrasound resource in liquid

由光声热弹性的基本方程出发 ,从理论和实验上研究了液体在激光直接照射下产生超声波时激光束半径对声源的影响 .在二维情况下 ,忽略热扩散效应 ,利用汉克尔积分变换法和最陡下降法 ,求解热扩散方程和波动方程 ,得出了位移的解析表达式 .讨论了激光束半径对声源指向性的影响 ,并用数值计算方法和绘图软件 ,画出激光束半径对声源指向性影响的理论曲线图 .

The sound source which is generated by laser in liquid is studied theoretically and experimentally on the basis of the thermoplastic equation. The influence which the laser beam radius produces on the ultrasonically source is considered. In two dimensional model, the thermal diffusion effect is neglected. The thermal equation and wave equation are solved by the methods of Hankel transform and steepest descent, and the general expression of displacement is obtained. The influence of the laser beam radius on the sound directivity is analyzed. The theoretical curve of the sound directivity which is influenced by the laser beam radius is drawn by the numerical method and drawing software. In the end, the theoretical results are testified in the experiment.