| 摘要 |
PURPOSE:To allow measurement of the bulk sound velocity of a substrate under the state of non-piezoelectric ceramic without requiring any polarization or formation of electrode by applying ultrasonic wave to a sample substrate and causing interference between pulse waves reflected on the surface and the rear. CONSTITUTION:A high frequency signal from a tracking generator is converted by an RF switch into a burst wave which is passed through a circulator and applied to a plane wave acoustic lens 1 thence radiated, as an ultrasonic wave, to a sample substrate 4. Reflection waves P1, P2 from the surface and the rear of the sample 4 are converted through a lens 1 into electric signals which enters into a spectrum analyzer through an attenuator gate. In this regard, the pulse reflection waves P1, P2 are caused to interfere each other by sweeping the applying pulse frequency. The period of interfering frequency is proportional to the bulk wave sound velocity of the sample 4, which is determined by multiplying the period of interference frequency by two times of the thickness of the sample 4. |
