Goossens Jozefien, Martinez Loïc, Glorieux Christ, Wilkie-Chancellier Nicolas, Ehssein Chighali Ould, Serfaty Stéphane
Laboratorium voor Akoestiek en Thermische Fysica, Departement Natuurkunde en sterrenkunde, Celestijnenlaan 200D, 3001 Heverlee, Belgium.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e1179-82. doi: 10.1016/j.ultras.2006.05.066. Epub 2006 Jun 5.
Laser ultrasonic detection is a versatile and highly sensitive tool for the observation of surface waves. In the following study, laser ultrasonic detection is used for the experimental study of spurious normal vibration modes of a disk quartz sensor excited by a voltage pulse. The AT cut crystal (cut of the crystal relative to the the main crystallographic axis is 35.25 degrees) is optimal for generating mainly thickness-shear vibrations (central frequency 6 MHz) on the quartz surface. However, resulting from shear-to-longitudinal and shear-to-surface mode conversion, and from the weak coupling with the other crystallographic axes, other modes (thickness-compressional and bending modes) are always present in the plate response. Since the laser vibrometer is sensitive to normal displacements, the laser investigation shows waves that can be considered as unwanted for the AT quartz used as a shear sensor. The scanned three dimensional (3D) amplitude-space-time signals are carefully analysed using their representation in three dual Fourier domains (space-time, wave number-frequency). Results on the transient analysis of the waves, the normal bending modes and the dispersion curves are shown.
激光超声检测是一种用于观测表面波的多功能且高灵敏度的工具。在接下来的研究中，激光超声检测被用于对由电压脉冲激发的圆盘石英传感器的寄生法向振动模式进行实验研究。AT 切晶体（晶体相对于主晶轴的切割角度为 35.25 度）最适合在石英表面主要产生厚度剪切振动（中心频率 6 兆赫兹）。然而，由于剪切到纵向和剪切到表面模式的转换，以及与其他晶轴的弱耦合，在平板响应中总是存在其他模式（厚度压缩和弯曲模式）。由于激光测振仪对法向位移敏感，激光研究显示出的波对于用作剪切传感器的 AT 石英来说可被视为不需要的。利用在三个双傅里叶域（时空、波数频率）中的表示，对扫描的三维（3D）幅度 - 空间 - 时间信号进行了仔细分析。展示了关于波的瞬态分析、法向弯曲模式和色散曲线的结果。
