Optical fibre interferometric gyrometer with polarization switching
AssigneeThomson-CSF
InventorGeorges Pircher
Life of this patent
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Abstract
An interferometric gyrometer using a laser source and beam separator forming two waves each directed to one end of a wound monomode fiber and recombined after passage. A permanent phase shift equal to .pi./2 is introduced between the two waves emerging from the ends of the fiber, and a switch is alternately shifted between a state transmitting the recombined waves and a state inverting the phase of the recombined waves. A synchronous demodulator, receiving the detected and amplified signal and a signal synchronous with the control signal applied to the switch supplies a signal proportional to the speed of rotation of the gyrometer.
Claims5
An optical fiber interferometric gyrometer comprising:
- a laser source emitting a linearly polarised monochromatic beam;
- an optical fiber wound around the axis of rotation of the gyrometer;
- means for separating said beam into two waves, directing said waves for travel through said fiber in opposite directions and recombining the waves after travel through said fiber;
- switching means having a first state transmitting the recombined waves without modification and a second state inverting the phase of said recombined waves;
- fixed phase shift means for introducing a fixed phase shift equal to .pi./2 between the two waves;
- modulating means for producing a signal for alternately shifting said switching means between said first and second states;
- means for detecting the recombined waves after passage through said switching means and said fixed phase shift means;
- and
- a synchronous demodulator connected to said detector means, and to said modulating means for producing a signal indicating the rotation speed of the gyrometer.
Dependencies are inferred from the claim text.