| 摘要 |
PURPOSE:To secure effective beam width up to a long distance and to further improve distance resolution by providing wedges and vibrators with curvature in a convex lens shape and providing a damper consisting principally of high- density tungsten on the back surface side of the vibrator. CONSTITUTION:The wedges 3' and 4' for transmission and reception which have curved surfaces in the convex lens shape are fitted with the curved-surface vibrators 1' and 2' for transmission and reception which have the same curvature. Consequently, ultrasonic wave beams 10 and 11 emitted by the vibrator 1' are propagated in a test body 7 while spreading and effective beam width which is equal to or larger than the lengthwise size of the vibrator 1' is obtained even in a long-distance sound field. Further, the high-density damper 15 formed by pressing and compacting tungsten powder is provided on the back surface side of the vibrators 1' and 2', so the free vibration of the vibrators 1' and 2' can be suppressed abruptly, so that the vibration frequency decreases and the distance resolution is improved. Consequently, the width of a reflection echo becomes narrow and the separation of, specially, reflection echo F2 from a defect 9 close to the bottom surface and bottom surface echo B is made complete. |
