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Fibre optic gyroscope with nulling feedback control loop

  • US 4,834,538 A
  • Filed: 01/20/1988
  • Issued: 05/30/1989
  • Est. Priority Date: 03/19/1987
  • Status: Expired due to Fees
First Claim
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1. A fibre optic gyroscope arrangement comprising:

  • a length of optical fibre formed in a loop,a laser light source,means for launching light from the laser source simultaneously into opposite ends of the length of fibre, whereby the light is travelling in counter rotating directions in the loop,means for determining differences between the two effective path lengths of the counter rotating light in the fibre,means for modulating the light launched into one end of the fibre at first and second frequencies f and 2f respectively, where f=1/4t with t being the transit time of the light in the fibre loop,means for adjusting the amplitude of the 2f waveform in a closed loop feedback system by applying a feedback voltage to the modulating means so as to null the f component of the gyroscope output,means for varying the wavelength of the laser light source for an initial period of time at switch-on of the gyroscope, andmeans for subsequently operating the laser light source at a fixed wavelength.

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