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Structural monitoring sensor system

  • US 6,181,841 B1
  • Filed: 01/11/2000
  • Issued: 01/30/2001
  • Est. Priority Date: 09/14/1995
  • Status: Expired due to Fees
First Claim
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1. An optical sensor for detecting movement of a first element relative to a second element along a first axis, said optical sensor comprising:

  • (a) a light source for generating a pulse of light;

    (b) an optical receiver for receiving a pulse of light;

    (c) an optical coupler;

    (d) a first optical conduit operatively connected to said light source and to said optical coupler, (e) a second optical conduit operatively connected to said optical receiver and to said optical coupler;

    (f) an optical encoder comprising;

    (1) a reflector grid fixed to said fat element and having a plurality of evenly spaced uniform reflective surfaces emending in a first plane which is parallel to said first axis;

    (2) a transmitter grid fixed to said second element and having a plurality of evenly spaced light impervious surfaces extending in a second plane which is parallel to said first plane, the spaces between said light impervious surfaces being pervious to light, the spaces between said light impervious surfaces being optically aligned with said reflective surfaces transversely of said first and second planes; and

    (3) wherein one of said reflector grid and said transmitter grid having first and second substantially identical grid portions, said second grid portion being offset from said first grid portion along said first axis by a distance which is sufficient to resolve direction of movement of said first element relative to said second element by the principle of quadrature;

    (g) a first optical fiber operatively connected to said optical coupler and to said transmitter grid, said first optical fiber having an end surface for transmitting a pulse of light to said reflector grid and for receiving a reflected pulse of light from said reflector grid along a second axis which is transverse to said first and second planes, the end surface of said first optical fiber being optically aligned with said first grid portion; and

    (h) a second optical fiber operatively connected to said optical coupler and to said transmitter grid, said second optical fiber having an end surface for transmitting a pulse of light to said reflector grid and for receiving a reflected pulse of light from said reflector grid along a second axis which is transverse to said first and second planes, said second optical fiber being optically aligned with said second grid portion, said second optical fiber being substantially longer than said first fiber optical fiber so that the pulse of light which is reflected from said second grid portion takes longer to reach said optical detector than the pulse of light which is reflected from said first grid portion.

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