环形定子的激光致表面波机理及可视化探测研究

Theoretical and visualization study of laserinduced surface acoustic wave on annular stator

开展了用于新型激光驱动马达的环形定子的激光致表面波机理及实验研究.提出一种带有凹槽阵列结构的环形定子新设计,建立了激光在环形定子表面激发表面波的物理模型,揭示了影响表面波幅值的关键因素;采用一种新颖的激光致表面波可视化探测方法,在波长1053 nm,脉宽30 ns,单脉冲能量1 mJ的激光激发下,对表面波在铜质环形定子表面的传播特性进行了可视化探测实验.理论与实验研究表明:当激发光斑的位置紧邻凹槽阵列时,沿着圆环向凹槽方向传播的表面波会被齿状凹槽阵列迅速衰减和吸收,而沿着圆环向远离凹槽方向传播的表面波能够持续传递,从而首次实现了激光致表面波在环形定子上的单向传播;而对没有凹槽阵列结构的圆环进行的对比实验表明,激光致表面波在圆环表面双向传播,最终因相互混叠和串扰等而处于混乱状态.由激光在该种环形定子表面激发出的单向表面波,可望在光致表面波马达及驱动机构中获得应用.

The mechanism of laser-induced surface acoustic wave （SAW） on annular stator is theoretically and experimentally studied. An annular stator with groove arrays is specifically designed. The physical model of laser-induced SAW on the stator is established, and the key factors influencing the wave amplitude are disclosed. We introduce a new kind of visualization method to detect laser-induced SAW on the copper-made annular stator, under a pulsed laser of 1053 nm wavelength, 30 ns pulse width and 1 mJ pulse energy. The results show that when the location of the irradiating laser spot is near the groove arrays, the SAW propagating towards the groove will be attenuated and absorbed immediately by the groove arrays, while the SAW away from the groove can keep propagating along the stator surface. In this way, the one-way propagation of laser-induced SAW is successfully acquired. In the contrast experiments, the laser-induced SAW travels in both directions on a copper ring without groove arrays, resulting in a chaotic state of the surface acoustic wave. The one-way SAW induced by pulsed laser on the annular stator will be used in the laser-driven SAW motor in the future.