| 摘要 |
PURPOSE:To reduce the attenuation of ultrasonic waves by utilizing a high polymer film including air foams for the acoustic matching film and thereby making the density of the tone adjusting layer small. CONSTITUTION:On the main surface 11 of a piezoelectric vibrator 10 that transmits/receives ultrasonic waves, an acoustic matching layer made of the high polymer porous film 12 which incorporates holes 3 for matching acoustic impedance between the air that functions as an acoustic load and the surface. As the result of this constitution with the film 12 which does not utilize small hollow globes of compound materials, the density of the film can be made small, and also, scattering due to the said globes is prevented. Therefore, the attenuation of the ultrasonic waves are reduced. |
