| 摘要 |
PURPOSE:To obtain an ultrasonic wave picture with high resolution in an azimuth direction and a distance (depth) direction. CONSTITUTION:A 1st acoustic matching layer 5 is provided to a face of a piezoelectric vibrator 1 for an ultrasonic wave transmission reception side at a region except part of an outer end of an opening so as to be gradually thinner toward an outer ridge. A 2nd acoustic matching layer 6 is provided to an outer edge of the piezoelectric vibrator 1 and a front side of the 1st acoustic matching layer 5. Since the 1st acoustic matching layer 5 is not in existence at the outer end of the opening, a sound pressure around the center of the opening of the piezoelectric vibrator 1 is high and a sound pressure at an outer edge is gradually lower, the side lobe level is reduced by giving a weight to the sound pressure to make a long focus deep and the frequency characteristic closer to the regular distribution over a broad band is obtained. |
