测量液体非线性参量的光声方法

本文描述了一种用光声脉冲测量液体非线性参量B/A的新方法。用聚焦脉冲激光束通过光击穿机制在液体中激发光声脉冲。在测量距离范围内,光声脉冲声压幅值随传播距离的变化接近球面扩展衰减规律。根据光声脉冲传播一定距离后前沿上升时间的变化,测定了液体的B/A。和有限束宽的平面脉冲声波相比,用球面脉冲声波可以避免衍射的影响。用此法测量了水的非线性参量,得到了满意的结果。

Photoacoustic method for measurement of the nonlinearity parameter of liquids

A new method for measurement of the nonlinearity parameter B/A of liquids by means of photoacoustic pulses is described. The photoacoustic pluse is generated by focused laser pulse via laser-induced breakdown mechanism in liquids. In the distance range, in which the photoacoustic pulses have been measured, the variation of the amplitude of photoacoustic pulse with propagation distance is very close to the spherical attenuation law. From the variation of the rise time of photoacoustic pulse wavefront after a propagating a certain distance, the parameter B/A of liquid is determined. Comparing with the plane pulsed wave with restricted beam, the effect of diffraction may be avoided by using the spherical pulsed wave. The nonlinearity parameter B/A of water is obtained by the present method. The results are reasonably good.