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Phase nulling optical gyroscope

  • US 4,735,506 A
  • Filed: 04/01/1985
  • Issued: 04/05/1988
  • Est. Priority Date: 04/01/1985
  • Status: Expired due to Fees
First Claim
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1. A fiber optic rotation sensor, comprising:

  • a length of optical fiber including a sensing coil formed therein;

    means for introducing a pair of counterpropagating light waves into said sensing coil such that rotation of said sensing coil causes a phase shift between the counterpropagating light waves, said phase shift being indicative of the rotation rate of said sensing coil;

    fiber optic frequency shifting means formed to interact with said length of optical fiber for producing a frequency shift in each of said counterpropagating waves to compensate for phase shifts caused by rotation of said sensing coil;

    means for producing a frequency shift signal indicative of the frequency shift produced by said fiber optic frequency shifting means to indicate the rotation rate of said sensing coil, the frequency shift signal being an oscillatory signal having a frequency indicative of the rotation rate of the sensing coil, each oscillation of the frequency shift signal being indicative of a predetermined incremental angular displacement of said sensing coil; and

    a phase modulator formed in said optical fiber for modulating the phase of a first one of said counterpropagating waves before said first wave impinges upon said sensing coil and for modulating the phase of the second wave after said second wave has propagated through said sensing coil.

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