METHOD OF MEASURING PHASE SIGNAL OF A FIBER-OPTIC INTERFEROMETRIC SENSOR Russian patent published in 2020 - IPC G01B9/02 G01C19/72 

FIELD: optics.

SUBSTANCE: invention relates to fiber optics and can be used for recording phase signals of fiber-optic interferometric sensors. Method of measuring a phase signal of a fiber-optic interferometric sensor includes measuring an interference signal I (t), generation of two auxiliary phase modulation signals cos(ω₀t) and cos(2ω₀t), where ω₀ – their cyclic frequency, and with their help conversion by synchronous detection of the measured interference signal into two signals S₁(t)=-BJ₁(C)sin(ϕ(t)) and S₂(t)=-BJ₂(C)cos(ϕ(t)), where B is coefficient proportional to amplitude of interference signal on photodetector, S₁(t) and S₂(t) is the first and second harmonics of the interference signal, J₁(C) and J₂(C) – Bessel functions of first and second order first-order Bessel functions, ϕ(t) is the measured phase signal, two additional phase modulation signals cos(3ω₀t) and cos(4ω₀t) and using them to synchronously detect the measured interference signal I(t) into two signals S₃(t)=BJ₃(C) sin(ϕ(t)) and S₄(t)=BJ₄(C)cos(ϕ(t)), where S₃(t) and S₄(t) is the third and fourth harmonics of the interference signal, J₃(C) and J₄(C) – first-order Bessel functions of the third and fourth orders, and calculating an output measured phase signal value in accordance with formula

EFFECT: high accuracy of measuring phase signals by eliminating the effect of measuring the depth of auxiliary phase modulation on the interference signal in the range of its values from 0,9 to 5 radians.

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