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Fiber-optic seismic sensor

  • US 4,534,222 A
  • Filed: 08/08/1983
  • Issued: 08/13/1985
  • Est. Priority Date: 08/08/1983
  • Status: Expired due to Term
First Claim
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1. A vibration sensor including:

  • a first optical fiber having;

    an input end;

    an output end; and

    a coil portion therebetween of a first predetermined optical path length when said sensor is not subject to vibration to be sensed;

    a second optical fiber having;

    an input end;

    an output end; and

    a coil portion therebetween of a second predetermined optical path length when said sensor is not subject to vibration to be sensed;

    a closed body adapted to be coupled to the vibration to be sensed to vibrate said body, said coil portions of said first and second optical fibers being positioned within said body; and

    means to vary said optical path length of at least said first optical fiber coil portion with the vibration of said body including;

    a mass having;

    a first side; and

    a second opposite side, said first and second sides being orientated generally at right angles to the vibration to be sensed; and

    elastic means to fill said body and encapsulate said coil portions of said first and second optical fibers and said mass within said body, said mass being positioned between said coil portion of said first optical fiber and said coil portion of said second optical fiber, whereby movement of said mass within said body caused by vibration of said body causes said elastic means to exert differential pressures between said coil portions of said first and second optical fibers.

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