Sagnac phase shift tracing method of optical fiber gyroscope

Abstract

The invention discloses a Sagnac phase shift tracing method of an optical fiber gyroscope, belonging to the field of optical fiber sensors. The method comprises the following steps: 1) carrying out filter demodulation on the detected signal when K equals to zero to obtain first and second harmonic demodulation signals S1(0) and S2(0) when K equals to zero; 2) calculating the Sagnac phase shift (0) of the optical fiber gyroscope when k equals to zero based on the S1(0) and S2(0), and initializing the initial value of a phase offset parameter PB to zero; and 3) carrying out filter demodulation on the detected signals collected at a later K moment to obtain first and second harmonic demodulation signals S1(k) and S2(k) at the present moment; and based on S1(k), S2(k), a first harmonic demodulation signal S1(k-1) and a second harmonic demodulation signal S2(k-1) at the previous moment, determining a Sagnac phase shift (k) value at the present moment. The invention can greatly improve the dynamic range, precision and scale factor linearity of the high optical fiber gyroscope.

Description

technical field [0001] The invention belongs to the field of optical fiber sensing, in particular to a Sagnac phase shift tracking method of an optical fiber gyroscope. Background technique [0002] Fiber optic sensing technology is a new type of sensing technology that has been widely concerned. As one of the most important achievements in the field of fiber optic sensing, fiber optic gyroscopes are currently being widely studied and applied. The fiber optic gyroscope is an angular velocity measuring instrument based on the Sagnac effect. There are many possible working modes, such as: resonant type, interference type, slow light mode, etc. At present, the technology is relatively mature and can be put into large-scale use of fiber optic gyroscopes. It is an interferometric fiber optic gyroscope. Interferometric fiber optic gyroscopes have two basic structures: open-loop structure and closed-loop structure. [0003] The open-loop fiber optic gyroscope directly detects the...

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Problems solved by technology

The invention patent with the application number 200710160367.X extends the monotone Sagnac phase shift interval that the open-loop fiber optic gyro can measure from [-π / 2π / 2) mentioned in the above analysis to [-23π / 1623π through signal processing / 16), that is, expanded by 23 / 8 times, but the key point of this invention is that the phase modulator no longer works in the conventional state described above, but works in 5 modulation stages in one modulation cycle, and each stage has Different fixed modulation amplitudes, which require high precision of the modulation signal output by the phase modulator, the modulation amplitude needs to be strictly controlled, and the error of the modulation signal will affect the effect of the entire invention implementation

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