The main technology that fiber optic gyroscope needs to break through is the loss of sensitivity, the drift caused by noise and fiber birefringence, and the instability of the scale factor caused by the change of polarization state.
(1) Sensitivity disappears
As the rotation rate approaches zero, the sensitivity disappears. This is caused by the optical density in the detector being proportional to the cosine of the Sagnac phase shift.
(2) Noise problem
FOG noise is caused by Rayleigh backscatter. To achieve low noise, a light source with a small coherence length should be used.
(3) Drift caused by fiber birefringence
If two oppositely propagating light waves are on different optical paths, a drift will occur. The reason for the difference in optical path length is that single-mode fibers have two orthogonal polarization states, and these two polarization states generally propagate at different speeds. Due to environmental influences, the two orthogonal polarization states are randomly changed.
(4) The scale factor caused by the change of polarization state is unstable.
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