| 摘要 |
PURPOSE:To measure the real extent of attenuation of an ultrasonic wave by combining multiple information extracted from analysis in frequency of an ultrasonic wave output signal, and applying resulted information with arithmetic processing. CONSTITUTION:An ultrasonic wave generated by an ultrasonic wave transmitter and receiver 3 using laser light include a wide range spectrum up to tens MHz and is transmitted to intrude into a material. Then, a detected ultrasonic wave pulse echo signal while drawn on an oscilloscope 8 through an amplifier 4 is digitized by a high-speed wave memory 5 and read. On the basis of this read data, a computer 6 calculates the thickness of the material from a preset velocity of the ultrasonic wave and time intervals of the pulse train. Further, the high-speed Fourier transform of each pulse echo waveform is carried out to calculate the attenuation of each ultrasonic wave of preset frequencies f1-f3. Then, information variables increased by the frequency analysis are used in combination to find the real attenuation accompanying the propagation of the ultrasonic wave, reflection loss, and diffraction loss repsectively and separately, and reliable information for estimating the crystal particle size of the material and other various constants of the physical properties are obtained. |
