| 摘要 |
PURPOSE:To enable simple and on-line judgement based on theoretical grounds by oscillating a plurality of ultrasonic waves with different wave lengths to a subject to be evaluated and judging an inside state both in two phases of solid and liquid from the relation between a grain diameter per wave length and ultrasonic attenuation factor. CONSTITUTION:A transducer 4 for oscillating and receiving an ultrasonic wave is brought into contact with a subject to be evaluated 1 consisting of a solid phase 2 on the surface and a liquid phase 3 inside. At this time, the ultrasonic wave oscillated to the subject 1 is attenuated in the process of propagation in the subject, and the attenuation characteristic is different between the case of the solid phase 2 and that of the liquid phase 3. That is in the case of the solid phase 2, the attenuation of the ultrasonic wave is caused by diffusion and diffraction by grains, etc., but it is limited in a zone of more than lambda/10 against a wave length of an input wave. In the case of the liquid phase 3, on the contrary, a viscousity attenuation mechanism caused by motion of an inclusion unique to the liquid phase 3 works other than the attenuation mechanism of the solid phase 2 and it appears in a zone less than lambda/10. Thus, by measuring a difference of the relation between an input wave length and attenuation, an internal state of the subject in which both solid and liquid phases exist can be judged. |
