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Transducer hydrophone with filled reservoir

  • US 4,653,036 A
  • Filed: 10/23/1984
  • Issued: 03/24/1987
  • Est. Priority Date: 10/23/1984
  • Status: Expired due to Fees
First Claim
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1. A hydrophone device for use in probing the acoustic properties of a fluid medium, comprising:

  • supporting hoop means of a selected area;

    first sheet means of biaxially oriented polymer material secured in said hoop means and held thereby in a taut condition;

    means having a poled piezoelectrically active area of predetermined size, the selected area of said first sheet means defined by said hoop means being larger than the size of said poled piezoelectrically active area, and said poled piezoelectrically active area being located in said first sheet means and spaced from said hoop means such that said hoop means during use remains outside, and said poled piezoelectrically active area remains inside, the region of the medium subjected to the acoustic energy and the point being probed by said hydrophone device, said sheet means having respective outer and inner electrode means of electrically conductive material on opposite outer and inner surfaces of said poled piezoelectrically active area, said first sheet means having a thickness selected such that it is substantially acoustically transparent in said fluid medium, and first and second electrical leads on said first sheet means, electrically connected to said inner and outer electrode means, respectively, and extending toward the periphery of said first sheet means, said second electrical lead electrically connected to said hoop means, said hoop means connected to an outer conductor of a coaxial connector, said first electrical lead electrically connected to an inner conductor of said coaxial connector;

    an electrically conductive coating on the entire outer surface of said first sheet means, and in electrical contact with said hoop means;

    a reservoir defined by the inner surface of said first sheet means, said hoop means, and an electrically conductive backing means secured to and electrically connected to said hoop means and spaced from the inner surface of said first sheet means, said reservoir being filled by a low-dielectric constant material having an acoustic impedance which is about equal to that of said medium, a dielectric constant of less than about 4 and a volume resistivity of greater than about 1014 ohm-cm.

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