| 摘要 |
PURPOSE:To speed up the measurement of thickness of a sample by Fourier transforming, the power spectrum data, finding the period of variation in the intensity of the power spectrum, and calculating the thickness of the sample from the found frequency. CONSTITUTION:When a transmission trigger is outputted from a pulse control part 20 to a pulse transmission part 10, the transmission part 10 generates a single-shot pulse. This pulse wave is converted electracoustically by a transducer 11 into an ultrasonic wave pulse, which is passed through an acoustic lens 12, propagated in coupler liquid 15, and made incident on the sample 13. The reflected wave from the sample 13 is passed through the liquid 15 and lens 12 and converted by the transducer 11 into a reflected signal, which is amplified by a preamplification part 16. A gate part 17 gates the reflected signal and a sample reflected wave is extracted and inputted to a computer 21 through a sampling part 18 and an A/D conversion part 19. The computer 21 Fourier transforms the reflected wave from the sample to find the power spectrum, which is further Fourier transformed to calculate the thickness (d) from the found period fo and the sound velocity V. |
