正弦脉冲激光激发声波的热膨胀机制理论

阐述了激光与液体媒质作用通过热膨胀机制激发平面光声源的理论;针对激光脉冲为正弦波形的情况,求解出δ脉冲和长脉冲分别在约束界面和自由界面下产生声脉冲的解析解,通过仿真得到了声脉冲剖面,并对每种情况下产生的声波进行了对比分析;然后对液体中激光致声的光声转换效率进行了理论研究,对正弦波形δ脉冲和长脉冲激光分别在约束界面和自由界面下产生声脉冲的光声转换效率分别进行了理论分析和仿真,并讨论了液体媒质特性参数和激光参数对转换效率的影响,提出了提高转换效率的方案。

Theoretical study of thermoelastic mechanism for generating acoustic waves by a sinusoid laser pulse

The theory of thermoelastic mechanism for generating plane acoustic wave by laser pulses in liquid is elaborated firstly.Sinusoid laser pulses are taken for example,and the analytic solutions of the acoustic pulses induced by a δ laser pulse and a long pulse under the conditions of rigid interface and free surface are found.And then the photoacoustic pulse sections are obtained through emulation.And the acoustic waves generated under these conditions are compared.After that,the photoacoustic conversion efficiency is investigated theoretically.And the conversion efficiency induced by a sinusoid δ laser pulse and a sinusoid long pulse through thermoelastic mechanism in liquid under the conditions of rigid interface and free surface are studied and simulated theoretically.The influence of the characteristic parameters of the liquid and the sinusoid laser pulse on the conversion efficiency is discussed.And the measures to enhance the conversion efficiency are put forward.