相位干涉法测量表面声波速度的相对变化

本文提出了一种相位干涉法。用来测量表面声波速度的相对变化。因为它不需要测量表面声波速度与声传播长度的绝对值,与通常使用的脉冲法^[3,4]和相位比较法相比^[5],具有设备简单,测试容易的特点。我们测得127.86°—LiNbO₃表面金属化后,表面声波的相对变化ΔV/V_∞=0.02866,相对误差为0.25％。
如果能精确测定声传播路程的长度,则用本法也可以精确测出表面声波速度的绝对值。
文中给出了几种切割方向的LiNbO₃和石英的Δi>V/V_∞及V_∞的测试数据和误差分析。

MEASUREMENT OF THE RELATIVE CHANGE OF SAW VELOCITY BY INTERFERENCE METHOD

A phase interference method, for measurement of the relative change of surface acoustic wave velocities, is presented. In this method we only measure the frequencies and relative length ratio instead of the absolute value of SAW velocities and the propagation distance. It is superior to the conventional pulse technique and phase comparison method in the simplicity of measuring equipments and the easiness of measurement. We have got the relative change of SAW velocities on the metallized surface of 127.86° YX-LiNbO₃, ΔV/V_∞=0.02866. with relative error within 0.25%.
The method can also be used to measure the absolute volue of SAW velocity accurately if the length of propagation is measured accurately.
The test data of ΔV/V_∞ and V_∞ for several orientation of LiNbO₃ and quartz and the error analysis are given.