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Modulation frequency control in a fiber optic rotation sensor

  • US 5,090,809 A
  • Filed: 06/04/1990
  • Issued: 02/25/1992
  • Est. Priority Date: 06/04/1990
  • Status: Expired due to Term
First Claim
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1. Apparatus for controlling the frequency of a modulation signal applied to a pair of counter-propagating light waves in an optical waveguide loop, comprising:

  • signal generator means, for generating the modulation signal having a certain frequency;

    phase modulator means, for phase modulating said light waves in response to said modulation signal;

    means for combining said light waves to form an optical output signal; and

    detection means, for detecting said optical output signal, and for providing a feedback signal proportional to the magnitude of a component of said optical output signal, said magnitude of said component being proportional to any deviation in the frequency of the modulation signal from said certain frequency, said signal generator means being responsive to said feedback signal in generating the modulation signal at a frequency equal to said certain frequency, said magnitude of said component being driven to zero when the frequency of the modulation signal equals said certain frequency.

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