Acoustic transducer with liquid-immersed, pre-stressed piezoelectric actuator in acoustic impedance matched transducer housing

An acoustic transducer, comprising:

• a transducer housing surrounding a transducer housing interior;
• said transducer housing comprising a sidewall having a first surface and a second surface;
• said sidewall comprising a solid resin and fibers imbedded in said solid resin;
• wherein a first density of fibers imbedded within said solid resin at said first surface varies to a second density of fibers imbedded within said solid resin at said second surface;
• and wherein said sidewall has an acoustic impedance gradient between said first surface and said second surface;
• a liquid disposed within said transducer housing interior;
• said liquid having a first acoustic impedance;
• said first surface being adjacent said liquid;
• wherein an acoustic impedance of said first surface substantially matches said first acoustic impedance;
• wherein said second surface is adapted to engage a work material;
• said work material having a second acoustic impedance;
• wherein an acoustic impedance of said second surface substantially matches said second acoustic impedance;
• a piezoelectric member immersed in said liquid;
• and
• energizing means for electrically energizing said piezoelectric member;
• said energizing means comprising means for applying an alternating voltage to said piezoelectric member at a first frequency.