| 摘要 |
An ultrasound transducer for intravascular examinations comprises an interleaved series of eccentric elliptical electrodes disposed on the back face of a piezoelectric substrate that has been alternately poled in the thickness dimension. The back face of the transducer is coupled to air, while impedance-matching layers are on the front face of the transducer. The front face is concave spherical to provide a geometric focus. The electrodes are driven at an ultrasound frequency. This arrangement results in a longitudinal-mode ultrasound transmission through the front face of the transducer. The eccentricity of the electrodes precompensates for distortion imposed by a cylindrical window. The pitch (spacing) of the electrodes increases radially, reducing speckling in the ultrasound image. This transducer provides for high-frequency intravascular examinations, and thus correspondingly high-resolution images, without using impractically thin piezoelectric substrates. In addition, the geometric focus, the predistortion, and the speckle-reduction all reduce the artifacts in the resulting high-resolution ultrasound image.
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