三角波形激光脉冲在液体中致声的特性分析  

Analysis of characteristics of acoustic waves induced by triangular laser pulses

作　　者：李秋实[1] 罗洪[1,2] 胡永明[1] 倪明[1] 

机构地区：[1]国防科技大学光电科学与工程学院,长沙410073 [2]桂林空军学院,桂林541003

出　　处：《激光技术》2010年第3期409-412,共4页Laser Technology

摘　　要：为了研究激光脉冲波形对其在液体中致声特性的影响,基于激光致声的热膨胀机制机理,采用理论推导和数值仿真的方法,对三角波形激光脉冲激发声波的特性进行了分析。首先阐述了激光与液体媒质通过热膨胀机制作用激发平面光声源的理论;推导了激光脉冲为三角波形时在约束边界和自由边界下产生声脉冲的解析解,并通过仿真得到了声脉冲剖面;然后通过模拟得到了不同边界下激发光声脉冲的波形;最后分别推导了约束边界和自由边界下的光声转换效率,分析了转换效率的影响因素,并对不同边界下的转换效率进行了求解和对比。结果表明,该研究对激光致声技术的工程应用具有理论指导意义。To investigate the influence of the waveform of laser pulses on the characteristics of photoacoustic pulses, based on the theory of thermoelastic mechanism for generation of acoustic waves, the characteristics of acoustic waves induced by triangular laser pulses were analyzed by means of theoretical derivation and numerical simulation. Firstly, the theory of thermoelastic mechanism for generation of a plane acoustic source by laser pulses in liquid was elaborated firstly. The analytic expressions of the acoustic pulses induced by laser pulses at the constraint margin and free margin were deduced when the laser waveform was triangular, and the sections of the photoacoustic pulses were obtained through emulation. Secondly, the waveform of the photoacoustic pulse was simulated. Finally, the photoacoustic conversion efficiency was deduced and the influencing factors were analyzed. And then the conversion efficiency at rigid margin and free margin were solved and compared. The obtained results can supply theoretical instruction for the engineering application of the technique of laser generation of acoustic waves.

关 键 词：激光技术 激光致声 热膨胀机制 三角脉冲 光声脉冲剖面 光声脉冲波形 转换效率 

分 类 号：O426.3[理学—声学]