| 摘要 |
PURPOSE:To enable the focusing of an ultrasonic beam as desired by a method wherein a cavity part is formed at a tip hard part of an inserting part with the shape of the tip hard part made circular in outline and an internal wall of the cavity part is formed into a concave curved surface with a specified radius of curvature. CONSTITUTION:An ultrasonic transmitter/receiver 22 is housed in a cavity part 21 of a cap 20 screwed down at the tip of a tip hard part 2c of an inserting part 2. Here, when a radius of curvature of a curved part 21a formed on the internal wall of the cavity part 21 is almost equal to that of an outer circumferential body of the cap 20, an ultrasonic propagation medium in the cap 20 is circular arc with the radius of curvature thereof almost the same in a direction (a direction orthogonal to the scanning) of a horizontally sectioned surface as well as in a direction (in a direction of scanning) of a vertically sectioned surface, hence being spherical as a whole. Therefore, the ultrasonic propagation medium functions as acoustic lens, depending on a difference between an acoustic impedance of the ultrasonic propagation medium in the cavity part 21 and an acoustic impedance in the cap 20 and in vivo, thereby enabling the focusing of an ultrasonic beam with a width thereof almost the same in a direction orthogonal to the direction of scanning and the slender spot. |
