Ing R K, Fink M
Lab Ondes et Acoust., Univ. Denis Diderot, Paris.
IEEE Trans Ultrason Ferroelectr Freq Control. 1998;45(4):1032-43. doi: 10.1109/58.710586.
Lamb waves are extensively involved in plate structure inspection because of their guided nature. However, their dispersive nature often limits their use in flaw detection. In this paper we show that the use of a time-reversal mirror (TRM) allows to automatically compensate for the dispersive nature of Lamb waves. Experiments showing the spatial and temporal behavior of time-reversed Lamb waves, demonstrate the ability of TRMs to self-focus and to recompress dispersive pulses. This is demonstrated in a set of experiments in which a broadband ultrasonic laser source is used to simulate a point Lamb wave source and an optical interferometer is used to map the time reversed elastic field. We also show that TRM may work in pulse echo mode and allows to detect and to focus along large 2-D plates on any flaws located in the inspected area.
由于兰姆波的导波特性，其广泛应用于板结构检测。然而，其色散特性常常限制了它们在探伤中的应用。在本文中，我们表明使用时间反转镜（TRM）可以自动补偿兰姆波的色散特性。展示时间反转兰姆波空间和时间行为的实验，证明了时间反转镜自聚焦和重新压缩色散脉冲的能力。在一组实验中得到了证明，其中使用宽带超声激光源模拟点兰姆波源，并使用光学干涉仪绘制时间反转弹性场。我们还表明，时间反转镜可以在脉冲回波模式下工作，并能够沿着大型二维板检测并聚焦在检测区域内的任何缺陷上。
