光源对激光超声信号特性的影响分析

Analysis of influence of light source on laser ultrasonic signal

通过已搭建好的激光超声检测实验平台,在保持相同激光脉冲能量和相同探测位置的条件下,重点研究了点光源与线光源产生的超声信号的特点和区别。研究了不同探测位置点光源与线光源激发出的超声信号幅值以及产生的超声信号波形。实验发现:在同一探测位置下,将点光源换成线光源后,产生的超声信号幅值由1.3V提高到1.7V,提高了0.4V;在探测位置逐渐增大的情况下,点光源激发出超声信号幅值的衰减幅度为75.78%,而线光源激发出的超声信号幅值的衰减幅度为34.92%。结果表明,在功率密度相同的情况下,线光源产生的超声信号要比点光源产生的超声信号幅值提高40.86%,产生较强的表面波,提高了信噪比。

In this paper, characteristics and differences of ultrasonic signals generated by point light source and line light source are mainly studied under condition of maintaining the same la- ser pulse energy and the same detection position through established laser ultrasonic testing platform. Amplitude of ultrasonic signal and waveform of ultrasonic signal generated by point light source and line light source are studied at different detection positions. It is found that am- plitude of ultrasonic signal is increased from 1.3 V to 1.7 V , which increased by 0.4 V after point light source is replaced by a line source in the same detection position. When detection po- sition is gradually increased, attenuation amplitude of ultrasonic signal amplitude excited by point light source is 75.78%, while attenuation amplitude of ultrasonic signal amplitude excited by line light source is 34.92%. Results show that under the same power density, ultrasonic sig- nal produced by line light source is increased by 40.86 % of ultrasonic signal amplitude generated by point light source, resulting in strong surface wave and better signal to noise ratio.