Modified Sokolov Camera Utilizing Condenser-Microphone Arrays of the Foil-Electret Type

  • Anant K. Nigam
  • J. C. French


This paper demonstrates the feasibility of an Electret Sokolov Camera (ESC) which employs electron-beam scanning of a subdivided-backplate foil-electret array. The mechanism of electron-beam reading is described and the different stable operating modes are identified. In one operating mode, the threshold ultrasound sensitivity of the ESC is estimated as better than 2×10-6 watts/cm2 for operation in water at 1MHz. This compares favorably with other real-time imaging systems such as the subdivided-foil-subdivided-backplate array and the conventional Sokolov camera (which employs a piezoelectricplate array). However, unlike the conventional Sokolov camera, the ESC does not suffer from limitations of physical and angular aperture. Furthermore, the transducing sensitivity of the ESC can be optimized independently of the material of the backplate. This added flexibility offers promise for further enhancement of the sensitivity.


Piezoelectric Plate Secondary Emission Metal Metal Insulation Secondary Current Angular Aperture 
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Copyright information

© Springer Science+Business Media New York 1974

Authors and Affiliations

  • Anant K. Nigam
    • 1
  • J. C. French
    • 1
  1. 1.Bell LaboratoriesMurray HillUSA

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