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Fiber optic displacement sensor

  • US 5,808,730 A
  • Filed: 04/08/1997
  • Issued: 09/15/1998
  • Est. Priority Date: 04/08/1997
  • Status: Expired due to Fees
First Claim
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1. A fiber optic displacement sensor for indicating the angle displacement and the rotational movement of a shaft or linear displacement of an object, comprising:

  • a first multichannel fiber optic bundle (MFOB A) for light transmission, which is split at one end into at least two channels, with at least one Reference Fiber Optic Channel for monitoring light intensity level of a light source;

    two optical tracks for light modulation, a first optical track having means for displacement modulation, and a second optical track having at least one section for detecting a reference position;

    a second multichannel fiber optic bundle (MFOB B) for receiving modulated light having at least two channels to split said received light and to introduce a phase difference of about 90 degrees between said light in said at least two channels;

    light detectors for receiving a modulated light and converting it into an electrical signal, said light detectors being connected to individual ends of said at least two channels of said second multichannel fiber optic bundle; and

    wherein said second Multichannel Fiber Optic Bundle for receiving modulated light further comprises groups of optical fibers within each of said at least two channels, said fibers each having a fiber core with a diameter, D1, such that D1 <

    W/2, where W is a period of modulation of said first type of optical track;

    fiber core centers of said fibers are placed with spacing L1 =m(W/4), m taking on integer values;

    within one group (row) of fibers, fiber core centers of said fibers are placed within a light path of said optical track and have spacing between centers L2 =n(W/2), n taking on integer values independently of m; and

    distance L3 between centers of said fibers included in different groups (rows) being given by L3 =m(W/4).

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