| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize setting of a focus at a close-range arbitrary position and realize ultrasonic wave measurement with higher azimuth resolution with a simple device configuration without using any acoustic lens at all in order to solve the problems of an enlarged device scale due to necessity of an acoustic lens for improving the close-range azimuth resolution and a difficulty in changing a focal distance.SOLUTION: An irradiation direction and a focal distance of a concave convergent wavefront to be formed are electronically controlled by using an FM signal to drive one-dimensionally-arrayed oscillators and then controlling a shape of the FM signal.</p> |
