利用激光多普勒测振仪的空气耦合超声声场测量*

进行了空气耦合超声声场测量的实验研究。使用激光多普勒测振仪测量由声波引起的激光路径上的介质折射率变化,进而得到空气和固体材料内部的时域瞬态声压。通过直接测量空耦换能器的辐射声功率,给出对单个空耦换能器灵敏度的直接评价方法。用空耦换能器激励K9玻璃板的漏兰姆波,观测到空气中的直达波和反射波、固体板内和空气中的漏兰姆波,实现了空气和固体中微弱声波的非侵入式实验测量,为空耦换能器的特性评估和空耦检测系统的声场测量提供了实验方法。

Air-coupled ultrasound acoustic field measurements using laser Doppler vibrometers

An experimental research of air-coupled acoustic field measurement is carried out. Using the laser Doppler vibrometer, the variation of refractive index of the media along the laser path can be measured, which is caused by acoustic waves. The temporal acoustic pressure signals in air or solid media can thus be obtained. By measuring the radiated acoustic power, a direct assessment method of the sensitivity of single air-coupled transducer is given. Leaky Lamb wave of K9 glass plate in the air excited by air-couple transducers is given. The temporal acoustic pressure signals of the direct and reflective waves in the air, the leaky Lamb wave both in solid and air are observed. The experimental measurement of low amplitude acoustic waves in air or solid media is achieved, providing a direct procedure for the characterization and assessment of air-coupled transducers and the measurement of the acoustic field of air-coupled testing systems.