固体中激光热弹超声的光穿透效应

Effect of optical penetration on laser generated thermoelastic ultrasound in solids

本文从热弹性基本方程出发，理论上研究了非金属固体材料受激光热弹激励超声时，光穿透效应对所产生声波的影响。在一维模型中，通过求解热扩散方程和热弹性位移方程，得到弹性位移的一般表达式，分析了材料的光叩收性质与声波位移振幅的关系。在二维模型中，对于轴对称分布的情况，忽略热扩散的影响，采用积分变换法求解热弹性运动方程，推导出远场区中的位移解析表达式。给出了纵波和横波的指向性图案，讨论了光穿透效应对声源指向性的影响。

The effect of optical penetration on laser thermoelastically- generated ultrasound in nonmetallic solids is studied theoretically on the basis of thermoelastic equations. In one-dimensional model,the general expression of wave displacement is obtained by solving the thermal diffusion and thermoelasticdisplacement equations, from which the influence of optical absorption on the displacement amplitude isanalyzed. In the case of two-dimensional axial symmetry, on neglecting the thermal diffusion, we solve thethermoelastic wave equation by means of the integral transform method and obtain analytic expressionsof the wave displacement components in the far-field. Directivity patterns of both longitudinal and shearwaves are presented and discussed.