圆形烧蚀光斑的纵波声场分析

圆形烧蚀光斑具有轴对称性且易于获取,在激光超声检测中有着广泛的应用。为了获得相应的纵波声场特性,建立了激励源模型,讨论了近场中声轴上声压幅值分布情况并获得了近场长度。利用面积积分,推导出声压振幅的表达式,并对远场中的声场能量进行了模拟。通过分析发现,远场中的纵波能量关于声束轴线呈对称分布,并且在轴线上达到最大值,此外光斑大小直接影响着纵波声场指向性。搭建了一套激光超声非接触式测量系统,基于互易原理并根据传播距离修正信号振幅,获得了指向性实验数据,验证了理论分析结果。

Investigation on the longitudinal wave sound field of circular ablation spot

The circular ablation spot is axisymmetric and easy to obtain,so it has a wide range of applications in laser ultrasonic inspection.In order to gain the corresponding characteristics of longitudinal wave sound field,an excitation source model is established.The amplitude distribution of sound pressure on the acoustic axis in the near field is discussed and the near field length is calculated.Using the area integral,the expression of the sound pressure amplitude in the far field is derived,and the sound field energy is simulated.Through analysis,it is found that the longitudinal wave energy is symmetrically distributed about the axis of the acoustic beam and reaches the maximum value on the axis.In addition,the spot size directly affects the directivity of the longitudinal wave sound field.A laser ultrasonic non-contact measurement system is set up.The signal amplitude is corrected according to the propagation distance,based on the reciprocity principle,directional experimental data is obtained and the theoretical analysis results are verified.