CN104075704A - Digital closed loop optical fiber gyroscope with double-interferometer system - Google Patents

Abstract

The invention discloses a digital closed loop optical fiber gyroscope with a double-interferometer system. The digital closed loop optical fiber gyroscope comprises a light source driver, a light source, a third beam splitter, a first angular speed sensing module, a second angular speed sensing module, an optical fiber ring and a logic circuit, wherein light emitted by the light source is divided into two beams of incident light after passing through the third beam splitter, and the two beams of incident light respectively enter the first angular speed sensing module and the second angular speed sensing module; the two modules uses the same optical fiber ring, so that two different interferometers are formed in the polarization maintaining optical fiber ring and respectively output signals; the logic circuit receives the signals and performs differential calculation to obtain speed information sensed by the interferometers. The digital closed loop optical fiber gyroscope disclosed by the invention controls a polarization state through a polarization beam splitting/combing device through the same polarization maintaining optical fiber ring, so that the two interferometers in different polarization states are formed in the optical fiber ring; the two polarization states are separated, so that the light-based double-polarization double-interferometer system is implemented, and the precision of the digital closed loop optical fiber gyroscope can be obviously improved, and the intensity noise of the light source is suppressed.

Description

A kind of digital closed-loop optic fiber gyroscope instrument with dual interferometer system

Technical field

The present invention relates to field of photoelectric technology, relate in particular to a kind of digital closed-loop optic fiber gyroscope instrument with dual interferometer system.

Background technology

Optical fibre gyro is a kind of New Solid inertia type instrument that inertial technology combines with photoelectron technology, Modern Manufacturing Technology, is current unique quiet gyro that can cover high, medium and low precision.Optical fibre gyro is angular speed of new generation, angular displacement sensor, for navigation and the attitude control in the fields such as satellite, aircraft, guided missile, naval vessel, vehicle, measurement exploration, robot, is the third generation gyro after electro-mechanical gyro and laser gyro.There is the features such as simple in structure, cost is low, startup fast (can realize zero start), reliability is high, anti shock and vibration ability is strong, the life-span is long.

Through the development of more than 30 years, at present from development trend, other gyros of replacement are become main flow by optical fibre gyro (FOG).But the main sensitive element of optical fibre gyro is the fiber optic loop by optical fiber coiling.Because optical fiber itself can responsive multiple physical quantity, cause the various nonreciprocal error of optical fibre gyro, improve optical fibre gyro precision if therefore want, must be suppressed various interference, and one of effective means that improves optical fibre gyro precision is to increase fiber optic loop, and increase the increase that fiber optic loop length causes error equally.

Summary of the invention

In view of above-mentioned analysis, the present invention aims to provide a kind of digital closed-loop optic fiber gyroscope instrument with dual interferometer system, in order to the problem that solves existing fiber Gyro Precision not or error ratio is larger.

Object of the present invention is mainly achieved through the following technical solutions:

The invention provides a kind of digital closed-loop optic fiber gyroscope instrument with dual interferometer system, comprising: light generation module, light processing module and difference are resolved module, wherein,

Light generation module, comprises that light source and light source drive, and the light that light source sends after driving the constant current source producing to drive by light source passes through after point three beams device, forms two bundle incident lights, enters respectively the responsive module of the first angular velocity and the second angular velocity sensitivity module;

Light processing unit, comprise: the 3rd beam splitter, the first angular velocity sensing unit and the second angular velocity sensing unit, wherein, the 3rd beam splitter is divided into two-way incident light for the light that light source is sent and enters respectively the first angular velocity sensing unit and the second angular velocity sensing unit, the first angular velocity sensing unit and the second angular velocity sensing unit are processed and are made to form in this fiber optic loop two different polarization states by polarization beam splitting/close bundle respectively, and are processed two polarization states are separated and output current signal by polarization beam splitting/close bundle;

Resolve unit, resolve for the current signal of above-mentioned two polarization states output is carried out to difference, obtain final result.

Further, described the first angular-sensitive unit comprises: the first beam splitter or circulator, the first integrated optical modulator, the first polarization beam splitting/bundling device, the first photodetector, the first front electric discharge road, an AD sample circuit, a DA feedback circuit; Described the second angular velocity sensing unit comprises: the second beam splitter or circulator, the second integrated optical modulator, the second polarization beam splitting/bundling device, the second photodetector, the second front electric discharge road, the 2nd AD sample circuit, the 2nd DA feedback circuit;

The leading up to of two-way incident light modulated by phase-modulator after the first beam splitter and is divided into two bunch polarisations, wherein after the A end of a bunch polarisation by the first polarization beam splitting/bundling device, enter fiber optic loop with original polarization state, and transmit in a clockwise direction and responsive rate information, then by the second polarization beam splitting/bundling device, export with original polarization state at the A ' of the second polarization beam splitting/bundling device port, then carry responsive rate information and return to the first modulator, and enter fiber optic loop with original polarization state after the A ' end of another light beam by the second polarization beam splitting/bundling device, with also responsive rate information of counterclockwise transmission, then by the first polarization beam splitting/bundling device, export with original polarization state at the A of the first polarization beam splitting/bundling device port, then carry responsive rate information and return to the first modulator, and by the first modulator compensation responsive to phase information, interfere at the first phase-modulator place, return to the first photodetector through the first coupling mechanism, the first photodetector will interfere the light intensity signal forming to be converted to current signal output, before first, put after conditioning, after an AD is converted into the processing of digital signal input logic circuit, by a DA feed back the first modulator compensation responsive to phase information,

Separately the leading up to of two-way incident light modulated by phase-modulator after the second beam splitter and is divided into two bunch polarisations, wherein original polarization state half-twist after a branch of B end that passes through the first polarization beam splitting/bundling device, then enter fiber optic loop, and transmit in a clockwise direction and responsive phase information, then by the second polarization beam splitting/bundling device, at the B ' of the second polarization beam splitting/bundling device port, polarized light half-twist is exported with original polarization state, then carry responsive rate information and return to the second modulator, and another light beam enters fiber optic loop by the rear original polarization state half-twist of B ' end of the second polarization beam splitting/bundling device, with also responsive rate information of counterclockwise transmission, then by the first polarization beam splitting/bundling device, at the B of the first polarization beam splitting/bundling device port, polarized light half-twist is exported with original polarization state, then carry responsive rate information and return to the second modulator, interfere at the second phase-modulator place, return to the second photodetector through the second coupling mechanism, the second photodetector will interfere the light intensity signal forming to be converted to current signal output, before second, put after conditioning, after the 2nd AD is converted into the processing of digital signal input logic circuit, by the 2nd DA feed back the second modulator compensation responsive to phase information.

The first acceleration sensitive unit is output as:

$I_D\left(t\right)=\frac{I_0}{2}\{1+\cos [\mathrm{\Δ}{\mathrm{\φ}}_m\left(t\right)+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f\left]\right\}$

The second angular velocity sensing unit is output as:

${I_D}^{\′}\left(t\right)=\frac{{I_0}^{\′}}{2}\{1+\cos [\mathrm{\Δ}{{\mathrm{\φ}}_m}^{\′}\left(t\right)+{{\mathrm{\φ}}_s}^{\′}-{{\mathrm{\φ}}_f}^{\′}\left]\right\}$

Wherein, I ₀, I ₀' be respectively the light intensity that arrives detector in the first angular velocity sensing unit and the second angular velocity sensing unit, Δ φ _m(t), Δ φ _m' (t) be respectively the phase modulation of phase-modulator in the first angular velocity sensing unit and the second angular velocity sensing unit, φ _sand φ _s' be respectively the Sagnac phase differential that the first angular velocity sensing unit and the second angular velocity sensing unit cause due to responsive speed, i.e. responsive angular speed, φ _f, φ _f' be respectively the feedback compensation phase shift of the first angular velocity sensing unit and the second angular velocity sensing unit.

Further, described difference is resolved unit and is resolved specifically for carrying out following difference:

If phase-modulator adds square-wave frequency modulation, depth of modulation is ze Yi road is output as:

$I_D({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})=0.5I_0(1+\cos (\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f))=0.5I_0(1-\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f))$

$I_D({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=0.5I_0(1+\cos (-\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f))=0.5I_0(1+\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f))$

Subtract each other by demodulation, and because closed loop is output as:

$I_D({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})-I_D({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=-0.5I_0\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f)-0.5I_0\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f)=0$

After closed loop, φ _s+ φ _ffor a small amount of, therefore:

φ _s+φ _f+φ _s+φ _f＝0

:

φ _f＝-φ _s

Another road output:

${I_D}^{\′}({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})=0.5{I_0}^{\′}(1+\cos (\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))=0.5{I_0}^{\′}(1-\sin ({\mathrm{\φ}}_s-{\mathrm{\φ}}_f))$

${I_D}^{\′}({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=0.5{I_0}^{\′}(1+\cos (-\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))=0.5{I_0}^{\′}(1+\sin ({\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))$

Subtract each other by demodulation, and because closed loop is output as:

φ _f'＝φ _s

Make gyro be output as:

φ＝φ _f-φ _f'

Therefore gyro is output as:

φ＝-2φ _s。

Further, described the first modulator and the second modulator are the phase-modulators based on integrated optics, have had partially, beam splitting/closed the fiber optical gyroscope of bundle, phase-modulation.

The feedback phase that described the first modulator and the second modulator apply is compensated for as staircase waveform feedback compensation, makes fibre optic gyroscope can realize closed loop and detects.

Described the first modulator and the second modulator all adopt a closed loop automatically to realize the online compensation of the index of modulation.

Beneficial effect of the present invention is as follows:

The present invention utilizes a polarization-maintaining fiber coil, adopt the polarization state in polarization beam splitting/bundling device control fiber optic loop, make to form in fiber optic loop two interferometers that polarization state is different, by polarization beam splitting/bundling device, two polarization states are separated, thereby realize the dual interferometer system of dual-polarization based on light, can significantly improve digital closed-loop optic fiber gyroscope precision and and suppress light source intensity noise.

Other features and advantages of the present invention will be set forth in the following description, and, part from instructions, become apparent, or by implement the present invention understand.Object of the present invention and other advantages can be realized and be obtained by specifically noted structure in write instructions, claims and accompanying drawing.

Brief description of the drawings

Fig. 1 is the concrete structure schematic diagram of digital closed-loop optic fiber gyroscope instrument described in the embodiment of the present invention.

Embodiment

Specifically describe the preferred embodiments of the present invention below in conjunction with accompanying drawing, wherein, accompanying drawing forms the application's part, and together with embodiments of the present invention for explaining principle of the present invention.

As shown in Figure 1, Fig. 1 is the structural representation of digital closed-loop optic fiber gyroscope instrument described in the embodiment of the present invention, mainly comprise: light generation module, the 3rd beam splitter, the responsive module of the first angular velocity, the responsive module of the second angular velocity, fiber optic loop and logical circuit, wherein

Light generation module, comprising: light source and optical drive, and the light that light source sends after driving the constant current source producing to drive by light source, by dividing after three beams device, forms two bundle incident lights, enters respectively the responsive module of the first angular velocity and the responsive module of the second angular velocity;

The responsive module of the responsive module of the first angular velocity and the second angular velocity, utilizes same fiber optic loop, makes to form in this polarization-maintaining fiber coil two different interferometers, and respectively output phase information to logical circuit;

Logical circuit, receives the phase information of the responsive module of the first angular velocity and the responsive module output of the second angular velocity and carries out Difference Solution calculation, obtains the rate information that interferometer sensitivity arrives.

As shown in Figure 1, Fig. 1 is the concrete structure schematic diagram of digital closed-loop optic fiber gyroscope instrument described in the embodiment of the present invention, wherein, the responsive module of the first angular velocity comprises: the first beam splitter or circulator, the first integrated optical modulator, the first polarization beam splitting/bundling device, the first photodetector, the first front electric discharge road, an AD sample circuit, a DA feedback circuit; The responsive module of the second angular velocity comprises: the second beam splitter or circulator, the second integrated optical modulator, the second polarization beam splitting/bundling device, the second photodetector, the second front electric discharge road, the 2nd AD sample circuit, the 2nd DA feedback circuit;

The light that light source sends, by dividing after three beams device, forms two bundle incident lights:

Wherein lead up to and modulated by phase-modulator after the first beam splitter and be divided into two bunch polarisations, wherein after a branch of end of the A by the first polarization beam splitting/bundling device, enter fiber optic loop with original polarization state, and transmit in a clockwise direction and responsive rate information, then by the second polarization beam splitting/bundling device, export with original polarization state at the A ' of the second polarization beam splitting/bundling device port, then carry responsive rate information and return to the first modulator, and enter fiber optic loop with original polarization state after the A ' end of another light beam by the second polarization beam splitting/bundling device, with also responsive rate information of counterclockwise transmission, then by the first polarization beam splitting/bundling device, export with original polarization state at the A of the first polarization beam splitting/bundling device port, then carry responsive rate information and return to the first modulator, and by the first modulator compensation responsive to phase information, interfere at the first phase-modulator place, return to the first photodetector through the first coupling mechanism, the first photodetector will interfere the light intensity signal forming to be converted to current signal output, before first, put after conditioning, be converted into digital signal logical circuit through an AD, logical circuit carries out obtaining after digital correlation demodulation the phase information of the first smooth processing unit sensitivity to the digital signal receiving, and by a DA feed back the first modulator compensation responsive to phase information,

The 3rd beam splitter forms another road incident light, by being modulated by phase-modulator after the second beam splitter and being divided into two bunch polarisations, wherein original polarization state half-twist after a branch of B end that passes through the first polarization beam splitting/bundling device, then enter fiber optic loop, and transmit in a clockwise direction and responsive phase information, then by the second polarization beam splitting/bundling device, at the B ' of the second polarization beam splitting/bundling device port, polarized light half-twist is exported with original polarization state, then carry responsive rate information and return to the second modulator, and another light beam enters fiber optic loop by the rear original polarization state half-twist of B ' end of the second polarization beam splitting/bundling device, with also responsive rate information of counterclockwise transmission, then by the first polarization beam splitting/bundling device, at the B of the first polarization beam splitting/bundling device port, polarized light half-twist is exported with original polarization state, then carry responsive rate information and return to the second modulator, interfere at the second phase-modulator place, return to the second photodetector through the second coupling mechanism, the second photodetector will interfere the light intensity signal forming to be converted to current signal output, before second, put after conditioning, be converted into digital signal input logic circuit logical circuit the digital signal receiving carried out obtaining after digital correlation demodulation the phase information of the second smooth processing unit sensitivity through the 2nd AD, and by the 2nd DA feed back the second modulator compensation responsive to phase information, in logical circuit, the responsive phase information obtaining respectively of two light processing unit outputs is carried out to difference after digital correlation demodulation resolves simultaneously, can obtain the rate information that two light processing unit cosensitizes arrive.

The first acceleration sensitive unit is output as:

$I_D\left(t\right)=\frac{I_0}{2}\{1+\cos [\mathrm{\Δ}{\mathrm{\φ}}_m\left(t\right)+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f\left]\right\}$

The second angular velocity sensing unit is output as:

${I_D}^{\′}\left(t\right)=\frac{{I_0}^{\′}}{2}\{1+\cos [\mathrm{\Δ}{{\mathrm{\φ}}_m}^{\′}\left(t\right)+{{\mathrm{\φ}}_s}^{\′}-{{\mathrm{\φ}}_f}^{\′}\left]\right\}$

Wherein, I ₀, I ₀' be respectively the light intensity that arrives detector in the first angular velocity sensing unit and the second angular velocity sensing unit, Δ φ _m(t), Δ φ _m' (t) be respectively the phase modulation of phase-modulator in the first angular velocity sensing unit and the second angular velocity sensing unit, φ _sand φ _s' be respectively the Sagnac phase differential that the first angular velocity sensing unit and the second angular velocity sensing unit cause due to responsive speed, i.e. responsive angular speed, φ _f, φ _f' be respectively the feedback compensation phase shift of the first angular velocity sensing unit and the second angular velocity sensing unit.

If phase-modulator adds square-wave frequency modulation, depth of modulation is ze Yi road is output as:

$I_D({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})=0.5I_0(1+\cos (\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f))=0.5I_0(1-\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f))$

$I_D({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=0.5I_0(1+\cos (-\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f))=0.5I_0(1+\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f))$

Subtract each other by demodulation, and because closed loop is output as:

$I_D({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})-I_D({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=-0.5I_0\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f)-0.5I_0\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f)=0$

After closed loop, φ _s+ φ _ffor a small amount of, therefore:

φ _s+φ _f+φ _s+φ _f＝0

:

φ _f＝-φ _s

Another road output:

${I_D}^{\′}({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})=0.5{I_0}^{\′}(1+\cos (\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))=0.5{I_0}^{\′}(1-\sin ({\mathrm{\φ}}_s-{\mathrm{\φ}}_f))$

${I_D}^{\′}({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=0.5{I_0}^{\′}(1+\cos (-\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))=0.5{I_0}^{\′}(1+\sin ({\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))$

Subtract each other by demodulation, and because closed loop is output as:

φ _f'＝φ _s

Make gyro be output as:

φ＝φ _f-φ _f'

Therefore gyro is output as:

φ＝-2φ _s

Can find out, it is complementary disturbing the phase place that dual-polarization difference type interferometer is caused, and can eliminate by follow-up data processing difference, and owing in fact having realized two interferometers, responsive speed phase place can double.

It should be noted that, above-mentioned light source can be the light sources such as SLD light source, Er-Doped superfluorescent fiber source, LED light source, and its wavelength can be 850nm, 1310nm, 1550nm equiwavelength; Above-mentioned fiber optic loop is to form with polarization maintaining optical fibre coiling, and polarization maintaining optical fibre can be that panda type polarization-preserving fiber, bow-tie type polarization maintaining optical fibre, ellipse core fibre, photonic crystal polarization maintaining optical fibre etc. have the optical fiber that polarization keeps function; Above-mentioned the 3rd beam splitter can be that polarization-maintaining coupler can be also monomode coupler; Above-mentioned the first beam splitter and the second beam splitter can be polarization-maintaining couplers, or monomode coupler and circulator; Above-mentioned the first modulator and the second modulator are the phase-modulators based on integrated optics, have had partially, beam splitting/closed the fiber optical gyroscope of bundle, phase-modulation; Modulation can adopt square-wave frequency modulation, sine wave modulation, and square-wave frequency modulation can, deng.And above-mentioned the first and second modulators can adopt a closed loop automatically to realize the online compensation of the index of modulation.

In sum, it is in fact to use same polarization-maintaining fiber coil that the embodiment of the present invention provides a kind of digital closed-loop optic fiber gyroscope instrument scheme with dual interferometer system, adopt the polarization state in polarization beam splitting/bundling device control fiber optic loop, make to form in fiber optic loop two interferometers that polarization state is different, by polarization beam splitting/bundling device, two polarization states are separated, thereby realize the dual interferometer system of the dual-polarization based on light.This scheme can significantly improve optical fibre gyro precision.

The above; only for preferably embodiment of the present invention, but protection scope of the present invention is not limited to this, is anyly familiar with in technical scope that those skilled in the art disclose in the present invention; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.

Claims (7)

1. a digital closed-loop optic fiber gyroscope instrument with dual interferometer system, is characterized in that, comprising: light generation module, light processing module and difference are resolved module, wherein,

Light generation module, comprises that light source and light source drive, and the light that light source sends after driving the constant current source producing to drive by light source passes through after point three beams device, forms two bundle incident lights, enters respectively the responsive module of the first angular velocity and the second angular velocity sensitivity module;

Light processing unit, comprise: the 3rd beam splitter, the first angular velocity sensing unit and the second angular velocity sensing unit, wherein, the 3rd beam splitter is divided into two-way incident light for the light that light source is sent and enters respectively the first angular velocity sensing unit and the second angular velocity sensing unit, the first angular velocity sensing unit and the second angular velocity sensing unit are processed and are made to form in this fiber optic loop two different polarization states by polarization beam splitting/close bundle respectively, and are processed two polarization states are separated and output current signal by polarization beam splitting/close bundle;

Resolve unit, resolve for the current signal of above-mentioned two polarization states output is carried out to difference, obtain final result.

2. digital closed-loop optic fiber gyroscope instrument according to claim 1, it is characterized in that, described the first angular-sensitive unit comprises: the first beam splitter or circulator, the first integrated optical modulator, the first polarization beam splitting/bundling device, the first photodetector, the first front electric discharge road, an AD sample circuit, a DA feedback circuit; Described the second angular velocity sensing unit comprises: the second beam splitter or circulator, the second integrated optical modulator, the second polarization beam splitting/bundling device, the second photodetector, the second front electric discharge road, the 2nd AD sample circuit, the 2nd DA feedback circuit;

The leading up to of two-way incident light modulated by phase-modulator after the first beam splitter and is divided into two bunch polarisations, wherein after the A end of a bunch polarisation by the first polarization beam splitting/bundling device, enter fiber optic loop with original polarization state, and transmit in a clockwise direction and responsive rate information, then by the second polarization beam splitting/bundling device, export with original polarization state at the A ' of the second polarization beam splitting/bundling device port, then carry responsive rate information and return to the first modulator, and enter fiber optic loop with original polarization state after the A ' end of another light beam by the second polarization beam splitting/bundling device, with also responsive rate information of counterclockwise transmission, then by the first polarization beam splitting/bundling device, export with original polarization state at the A of the first polarization beam splitting/bundling device port, then carry responsive rate information and return to the first modulator, and by the first modulator compensation responsive to phase information, interfere at the first phase-modulator place, return to the first photodetector through the first coupling mechanism, the first photodetector will interfere the light intensity signal forming to be converted to current signal output, before first, put after conditioning, after an AD is converted into the processing of digital signal input logic circuit, by a DA feed back the first modulator compensation responsive to phase information,

Separately the leading up to of two-way incident light modulated by phase-modulator after the second beam splitter and is divided into two bunch polarisations, wherein original polarization state half-twist after a branch of B end that passes through the first polarization beam splitting/bundling device, then enter fiber optic loop, and transmit in a clockwise direction and responsive phase information, then by the second polarization beam splitting/bundling device, at the B ' of the second polarization beam splitting/bundling device port, polarized light half-twist is exported with original polarization state, then carry responsive rate information and return to the second modulator, and another light beam enters fiber optic loop by the rear original polarization state half-twist of B ' end of the second polarization beam splitting/bundling device, with also responsive rate information of counterclockwise transmission, then by the first polarization beam splitting/bundling device, at the B of the first polarization beam splitting/bundling device port, polarized light half-twist is exported with original polarization state, then carry responsive rate information and return to the second modulator, interfere at the second phase-modulator place, return to the second photodetector through the second coupling mechanism, the second photodetector will interfere the light intensity signal forming to be converted to current signal output, before second, put after conditioning, after the 2nd AD is converted into the processing of digital signal input logic circuit, by the 2nd DA feed back the second modulator compensation responsive to phase information.

3. digital closed-loop optic fiber gyroscope instrument according to claim 1 and 2, is characterized in that:

The first acceleration sensitive unit is output as:

$I_D\left(t\right)=\frac{I_0}{2}\{1+\cos [\mathrm{\Δ}{\mathrm{\φ}}_m\left(t\right)+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f\left]\right\}$

The second angular velocity sensing unit is output as:

${I_D}^{\′}\left(t\right)=\frac{{I_0}^{\′}}{2}\{1+\cos [\mathrm{\Δ}{{\mathrm{\φ}}_m}^{\′}\left(t\right)+{{\mathrm{\φ}}_s}^{\′}-{{\mathrm{\φ}}_f}^{\′}\left]\right\}$

Wherein, I ₀, I ₀' be respectively the light intensity that arrives detector in the first angular velocity sensing unit and the second angular velocity sensing unit, Δ φ _m(t), Δ φ _m' (t) be respectively the phase modulation of phase-modulator in the first angular velocity sensing unit and the second angular velocity sensing unit, φ _sand φ _s' be respectively the Sagnac phase differential that the first angular velocity sensing unit and the second angular velocity sensing unit cause due to responsive speed, i.e. responsive angular speed, φ _f, φ _f' be respectively the feedback compensation phase shift of the first angular velocity sensing unit and the second angular velocity sensing unit.

4. digital closed-loop optic fiber gyroscope instrument according to claim 3, is characterized in that, described difference is resolved unit and resolved specifically for carrying out following difference:

If phase-modulator adds square-wave frequency modulation, depth of modulation is ze Yi road is output as:

$I_D({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})=0.5I_0(1+\cos (\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f))=0.5I_0(1-\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f))$

$I_D({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=0.5I_0(1+\cos (-\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s+{\mathrm{\φ}}_f))=0.5I_0(1+\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f))$

Subtract each other by demodulation, and because closed loop is output as:

$I_D({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})-I_D({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=-0.5I_0\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f)-0.5I_0\sin ({\mathrm{\φ}}_s+{\mathrm{\φ}}_f)=0$

After closed loop, φ _s+ φ _ffor a small amount of, therefore:

φ _s+φ _f+φ _s+φ _f＝0

:

φ _f＝-φ _s

Another road output:

${I_D}^{\′}({\mathrm{\φ}}_s,+\frac{\mathrm{\π}}{2})=0.5{I_0}^{\′}(1+\cos (\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))=0.5{I_0}^{\′}(1-\sin ({\mathrm{\φ}}_s-{\mathrm{\φ}}_f))$

${I_D}^{\′}({\mathrm{\φ}}_s,-\frac{\mathrm{\π}}{2})=0.5{I_0}^{\′}(1+\cos (-\frac{\mathrm{\π}}{2}+{\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))=0.5{I_0}^{\′}(1+\sin ({\mathrm{\φ}}_s-{{\mathrm{\φ}}_f}^{\′}))$

Subtract each other by demodulation, and because closed loop is output as:

φ _f'＝φ _s

Make gyro be output as:

φ＝φ _f-φ _f'

Therefore gyro is output as:

φ＝-2φ _s。

5. digital closed-loop optic fiber gyroscope instrument according to claim 2, is characterized in that: described the first modulator and the second modulator are the phase-modulators based on integrated optics, has had partially, beam splitting/closed the fiber optical gyroscope of bundle, phase-modulation.

6. digital closed-loop optic fiber gyroscope instrument according to claim 2, is characterized in that: the feedback phase that described the first modulator and the second modulator apply is compensated for as staircase waveform feedback compensation, makes fibre optic gyroscope can realize closed loop and detects.

7. digital closed-loop optic fiber gyroscope instrument according to claim 2, is characterized in that, described the first modulator and the second modulator all adopt a closed loop automatically to realize the online compensation of the index of modulation.