| 摘要 |
PURPOSE:To widen the range capable of measuring the speed of a surface wave of a sample by controlling the emitting angle of the bulk wave converted from a leakage Lumb wave by the control of the frequency of an applied AC signal. CONSTITUTION:One surface of a piezoelectric substrate 28 comes into contact with absorbing bodies 40, 42 and the other surface thereof has a transmitting screen electrode 30 and receiving screen electrodes 32, 34 formed thereto. A radio frequency pulse signal 108 for driving the electrode 30 is applied to the electrode 30 of a leakage Lamb wave element 26 from a radio frequency pulse generator 44. Those electrodes 30, 32, 34 are arranged to the substrate 28 along the longitudinal direction thereof and the bulk wave converted from the Lamb wave generated from the electrode 30 is emitted to a sample. At this time, the bulk waves emitted from the first and second regions of a transmission route are received by the electrodes 32, 34 and the change quantity of the second region to the velocity of the surface wave of the first region is calculated on the basis of the phase difference between both bulk waves. Whereupon, since the emitting angle of the bulk wave to the sample can be controlled on the basis of the signal 108, the corresponding surface wave is excited in the sample and the range capable of measuring the velocity of the surface wave can be widened. |
