以研究液体中激光声波的特点与应用为目的,从理论上分析脉冲激光在液体中产生的声波的波阵面、光声脉冲波形的特点,并用实验的方法观察脉冲CO2 激光光声脉冲的波形、频谱特性及光击穿现象。结果表明光声波的波阵面与吸收激光能量的媒质的形状有关;光声波的波形随激发机制而变化; CO2 脉冲激光在水中通过热膨胀机制激发的声波能量主要分布在100kHz以下,光击穿时水面可以观察到微爆炸和亮光现象。可以通过液体中光声效应现象和 光声信号波形的变化判断其激发机制,并确定液体的汽化与光击穿阈值,控制激发过程以获得确定特性的光声信号。
Abstract:
To get the characteristics and applications of laser acoustic effect in liquid, the shape of the wave front and waveform were analyzed theoretically, and laser acoustic effect induced by pulsed CO2 laserwas acquired experimentally. The results showed that acoustic wave frontwas decided by the shape of the medium absorbed the laser energy; the waveform of the laser acoustics changed with the exciting mechanism; frequency spectrum of acoustic wave induced by CO2 laser in water showed that acoustic energy distributed under 100kHzmainly, and lighting and micro－explodingwere observed when optics breakdown took place. In conclusion, excitingmechanisms of sound and thresholds of liquid could be judged from the experimental phenomenon; specified laser acoustic signal could be gotten by controlling the exciting process and condition.
