| 摘要 |
PURPOSE:To reduce an acoustic impedance, to increase the hardness and the absorption and attenuation of an ultrasonic wave and to improve the sensitivity by making a packing material with a material where glass bubbles whose diameter and specific gravity are specified values or below are mixed in a resin whose acoustic impedance is a specific value or below. CONSTITUTION:A packing material 3 is formed by mixing liquid resin and glass bubbles and curing the mixture. A resin whose acoustic impedance is 4.2Mrayls or below is used for a resin 4. A glass bubble 5 is formed by sealing air 7 into a hollow glass sphere 6, its diameter is smaller than wavelength of an ultrasonic wave propagated in the packing material 3 and its specific gravity is selected to be 0.39/cm<3> or below. Thus, the acoustic impedance of 2.0Mrayls or below is attained, the absorption and attenuation for the ultrasonic wave are increased, a hardness sufficiently supporting an ultrasonic wave vibrator is easily obtained and the sensitivity is improved. |
