Limited diffraction beam transducer of conical type with apodized vibration area

A conical transducer with an apodized vibration area is designed and fabricated using a piezocomposite material of 1-3 connectivity for creating limited-diffraction beams. The large electromechanical coupling coefficient k of the piezocomposite material lends itself to increase the transducer sensitivity. It is shown that an almost uniform -6 dB beamwidth of 6-9 wavelengths is obtained in the axial range of z=20 mm to 170 mm using the fabricated transducer 25 mm in diameter operating at 3.6 MHz. It is also demonstrated through a preliminary experiments of B-mode imaging that the high resolution capability maintains over a large depth