| 摘要 |
PURPOSE:To enable the high resolution of an ultrasonic image by suppressing the deterioration of a sound field due to the influence of a refraction generated since the sound speeds of a coupling solution and an acoustic window are different from the sound speed of an organism. CONSTITUTION:A delay time control circuit 11 gives a correction to a wave surface shape so that sound waves radiated from all sound sources can be converged in a position P1 separated by an equivalent curvature radius r2 from a recessed surface annular array ultrasonic transducer 2, and sets the delay time of a transmission/reception delay circuit so that a satisfactory convergent beam pattern can be obtained at a converged point. Namely, on a wave surface a (conventional spherical wave surface) before the correction indicated by a broken line, since ultrasonic beams radiated from respective transducers 2a-2e are phase-shifted at an acoustic window 5, a correct convergence can not be executed in the actual converged point. Then, by changing the spherical wave surface [wave surface (a) before the correction] into an S-shaped wave surface [wave surface (b) after the correction] to be indicated by the full line drawn, the influence of the refraction due to the acoustic window 5 can be corrected. |
