CN101718557B - United signal processing method of double-polarization interference type optical fiber gyroscope - Google Patents

Abstract

The invention discloses a united signal processing method of a double-polarization interference type optical fiber gyroscope, which belongs to the technical field of optical fiber communication. The method comprises the following steps of: (1) modulating the double-polarization interference type optical fiber gyroscope and outputting signal light at intervals by two linearly-polarized light inputlight paths; (2) measuring light power output on the two polarized light input light paths at different temperatures by a phase modulator; (3) according to a recorded temperature value and corresponding light power, determining the error ratio values rho (T) of two paths of equivalent rotation rates caused by temperature transition; (4) modulating the double-polarization interference type optical fiber gyroscope and outputting the signal light simultaneously by the two linearly-polarized light input light paths; (5) measuring the light power output on the two linearly-polarized light input light paths; (6) calculating rotation rates omega 1 and omega 2 respectively according to the light power measured in the step (5); and (7) calculating a modified rotation speed omega according to a formula omega=(omega1-rho(T)omega2)/(1-rho(T)). The invention carries out united analysis on noise in the double-polarization optical fiber gyroscope to obtain an accurate rotation angle speed.

Description

A kind of united signal processing method of double-polarization interference type optical fiber gyroscope

Technical field

The present invention relates to a kind of signal processing method of double polarizing light fiber gyroscope, relate in particular to a kind of united signal processing method of double-polarization interference type optical fiber gyroscope, belong to technical field of optical fiber communication.

Background technology

Optical fibre gyro is a kind of device that can the detection system space rotates rotation, is a kind of simple in structure, cost is lower, precision is high novel all solid state inertia device.The optical fibre gyro application is extensive, comprising: tactical weapon guidance, orientation, tracking and navigation in the Aero-Space, optics compass, automobile navigation instrument, dual-use fields such as robot control.

The ultimate principle of optical fibre gyro is based on Sagnac (sagnac) effect and the ring interferometer made.In the closed optical loop of a random geometry, send in opposite direction the two-beam of transmission from any point, if closed light path relative inertness space rotate along a certain direction, when two-beam returns starting point, relative variation can take place in phase place, and this phenomenon is called the Sagnac effect.Therefore, can be by detecting the interference light of two-way, the counter rotational angular velocity of releasing closed light path system.

The relative phase variation of the two-way light that rotation causes is called the Sagnac phase shift,

${\mathrm{\φ}}_s=2\mathrm{\π}\frac{\mathrm{LD}}{\stackrel{\‾}{\mathrm{\λ}}c}\mathrm{\Ω}---\left(1\right)$

Wherein, L is a fiber optic coils length, and D is the fiber optic coils diameter, and λ is the centre wavelength of flashlight, and c is the light velocity in the vacuum, and Ω is system's rotational angular velocity.By formula (1) as can be seen, Sagnac effect and phase shift φ thereof _sSize is irrelevant with the refractive index of medium.

The structure of Sagnac fibre optic interferometer needs satisfying reciprocity, makes two beam reversals transmission light wave have identical transport property.Reciprocity can play the effect of " common mode inhibition ", eliminates various ghost effects, thereby can measure delicately because the nonreciprocal Sagnac phase shift that rotation causes.

Particularly, reciprocity comprises the reciprocity of fiber coupler, single mode reciprocity and polarization reciprocity.

In traditional guarantor's bias tyre optical fibre gyro scheme,, only taked the single shaft mode of operation of fast axle or slow axis as the minimum reciprocal structure among Fig. 1.Just because of φ _sWith the irrelevant character of the refractive index of dielectric material, adopt the dual-polarization optical fiber Gyroscope Design scheme that is operated in two axles, by the two-way output signal is carried out check and analysis, can further improve the precision and the stability of system.

Summary of the invention

The object of the present invention is to provide a kind of united signal processing method of double-polarization interference type optical fiber gyroscope, it has obtained angular velocity of rotation accurately by the noise in the dual-polarization optical fiber gyro is carried out Conjoint Analysis.

Technical scheme of the present invention is:

A kind of united signal processing method of double-polarization interference type optical fiber gyroscope, wherein said double-polarization interference type optical fiber gyroscope is: two linearly polarized light input light paths are protected shift/beam splitter through one and are connected with a coupling mechanism, described coupling mechanism opposite side is connected with a fiber optic loop, be connected a phase-modulator between described fiber optic loop and the described coupling mechanism, the steps include:

1) modulation double-polarization interference type optical fiber gyroscope makes the two described linearly polarized light input light paths output signal light of property at interval;

2) measure described phase-modulator when different temperatures, the luminous power of exporting on the two described polarized light input light paths;

3), determine because the two-way equivalence speed of rotation error ratio that temperature transient causes according to the temperature value and the corresponding luminous power of record $\mathrm{\ρ}\left(T\right)=\left(n_1\frac{{\mathrm{dn}}_1}{\mathrm{dT}}\right)/\left(n_2\frac{{\mathrm{dn}}_2}{\mathrm{dT}}\right);$ N wherein ₁Be fast axle refractive index, n ₂Be the slow axis refractive index, T is a temperature;

4) modulation double-polarization interference type optical fiber gyroscope makes two described linearly polarized light input light paths output signal light simultaneously;

5) measure the luminous power of exporting on the two described linearly polarized light input light paths;

6) calculate speed of rotation Ω respectively according to step 5) institute photometry power ₁And Ω ₂

7) according to formula $\mathrm{\Ω}=\frac{{\mathrm{\Ω}}_1-\mathrm{\ρ}\left(T\right){\mathrm{\Ω}}_2}{1-\mathrm{\ρ}\left(T\right)}$ Calculate revised rotational speed Ω.

Further, described coupling mechanism is a polarization-maintaining coupler, and described fiber optic loop is a polarization-maintaining fiber coil.

Further, described linearly polarized light input light path comprises a signal modulator, and the linear polarization light source is connected with described guarantor's shift/beam splitter through described signal modulator.

Further, described linearly polarized light input light path comprises a circulator, and described signal modulator is connected with described guarantor's shift/beam splitter through described circulator, and described circulator is connected with a detector.

Further, described signal modulator is a phase-modulator.

Further, described signal modulator is an amplitude modulator.

Further, described ratio $\mathrm{\ρ}\left(T\right)=\left(n_1\frac{{\mathrm{dn}}_1}{\mathrm{dT}}\right)/\left(n_2\frac{{\mathrm{dn}}_2}{\mathrm{dT}}\right)$ Computing method be: at first the expression formula of interference signal luminous power is launched according to Bessel's function; Then according to step 2) luminous power surveyed, utilize that wave filter takes out wherein one, two, the amplitude of four-time harmonic; At last according to extracted one, two, φ when the amplitude of four-time harmonic solves different temperatures _Im, obtain the n under the different temperatures ₁/ n ₂Value, thus extrapolate dn _iThe curve of/dT is determined described ratio ρ (T); Wherein i=1 or 2 corresponds respectively to fast axle or slow axis.

Further, adopt kalman filter method to handle the signal of two described linearly polarized light input light paths respectively, eliminate temperature and float, obtain the speed of rotation Ω on two branch roads ₁' and Ω ₂'; Then according to formula Ω '=(η Ω ₂'-Ω ₁')/(η-1) calculate revised speed of rotation Ω ', η=ξ n wherein ₂/ n ₁, $\mathrm{\ξ}=\frac{{\left|E_1^{\mathrm{cw}}\right|}^2-{\left|E_1^{\mathrm{ccw}}\right|}^2}{{\left|E_2^{\mathrm{cw}}\right|}^2-{\left|E_2^{\mathrm{ccw}}\right|}^2},$ | E _i ^Cw| ²Be clockwise light intensity, | E _i ^Ccw| ²Be counterclockwise light intensity, i=1 or 2 corresponds respectively to fast axle or slow axis.

Further, utilize formula Ω _s=(Ω ₂Δ n ₁-Ω ₁Δ n ₂)/(Δ n ₁-Δ n ₂) calculate revised speed of rotation Ω _s, Δ n wherein ₁For causing that by stress or vibration fast axle local indexes of refraction changes Δ n ₂For causing that by stress or vibration the slow axis local indexes of refraction changes.

Fig. 2 is a dual-polarization optical fiber Gyroscope Design scheme synoptic diagram.Wide spectrum light source produces flashlight, becomes the light (rise and be biased on fast axle or the slow axis) of linear polarization after the polarizer rises partially, is divided into through the 3db beam splitter then that two-way power equates, the identical light in polarization direction.Two-way light by circulator 1 and circulator 2, passes through bundling device respectively then through identical or different phase places or amplitude premodulation mode.After bundling device can be realized one road light signal polarization rotated 90 ° with another road combiner.The light that comes out from bundling device becomes the fast axial light and the slow axial light of quadrature.Polarization-maintaining coupler and polarization maintaining optical fibre can be so that fast axial light and slow axial light transmit as the flashlight in the optical fibre gyro of minimum reciprocal structure respectively.Whole optical path after the circulator is reversible.Since the identical noise factor of experience in transmission course, and the Sagnac phase place is identical.If fast axle and slow axis refractive index are respectively n ₁And n ₂, then phase place can be expressed as form:

Δφ ₁＝Δφ _s+Δφ _n(n ₁)

Δφ ₂＝Δφ _s+Δφ _n(n ₂) (2)

By different modulation formats, we can carry out input at the port 3 of two circulators and the nonreciprocal port of coupling mechanism.According to experiment Device Design, detect the interference light intensity of fast axle and slow axis respectively at circulator 1 and circulator 2, carry out nonreciprocal signal light power detection at the nonreciprocal port of polarization-maintaining coupler.

Amplitude modulation(PAM) sign indicating number type as shown in Figure 3.Only on fast axle (or slow axis), there is the light signal input when amplitude modulation(PAM) makes, promptly gets back to single reciprocity structure.But the depolarized characteristic of device is undesirable to make the light on the fast and slow axis have certain conversion.The signal section of slow axis is mainly changed over by following mode from fast axle: (1) forward direction is (2) afterwards to by the 3db coupling mechanism time (coupling mechanism accomplish two-way polarization property all very height ratio is difficult) during by the 3db polarization-maintaining coupler; (3) back is to by beam splitter the time.Still adopt two-way to detect, just can obtain being transformed into the splitting ratio of slow axis (or fast axle) from fast axle (or slow axis).Obtain the overall characteristic of these several light-splitting device groups, method is provided for the correction of the angular velocity of rotation of surveying.

Make fast and slow axis have the process that clear signal is handled the orthogonal signal light simultaneously with modulation format below.

Can be expressed as from the interference signal of circulator output:

I _i＝I _0i{1+cos[φ _S+Δφ _i(t)]} (3)

I=1 wherein, 2, expression fast axle pattern and slow axis pattern respectively.The φ of two patterns _sIdentical, Δ φ _i(t) phase differential of introducing for the PZT phase modulation (PM), because fast and slow axis refractive index difference, the phase differential that the PZT phase-modulator is introduced has minute differences.When utilizing sine wave modulation,

Δφ _i(t)＝2φ _0isin(ω _mτ _i/2)cos[ω _m(t-τ _i/2)] (4)

Wherein, ω _mExpression PZT phase-modulator modulating frequency, m is the meaning of modulation, the modulation of expression PZT phase-modulator.(4) are brought into equation (3), can obtain according to the interference signal that Bessel's function launches be:

I _i＝I _0i{1+[J ₀(φ _im)+2∑(-1) ⁿJ _2n(φ _im)cos2nω _m(t-τ _i/2)]cos(φ _s)+ (5)

2∑(-1) ⁿ⁺¹J _2n-1(φ _m)sin[(2n-1)ω _m(t-τ _i/2)]sin(φ _s)}

Wherein, φ _Im=2 φ _0iSin (ω _mτ _i/ 2).

Utilize that wave filter takes out wherein one, two, the amplitude of four-time harmonic is respectively:

B _i1＝2I _0iJ ₁(φ _im)sinφ _s

B _i2＝2I _0iJ ₂(φ _im)cosφ _s

B _i4＝2I _0iJ ₄(φ _im)cosφ _s

By B _I2/ B _I4=J ₂(φ _Im)/J ₄(φ _Im), can try to achieve φ _ImValue; Again by B _I1/ B _I2=J ₁(φ _Im)/J ₂(φ _Im) tan (φ _s), can further try to achieve Sagnac phase shift φ _Si, obtain angular velocity of rotation Ω according to the geometric properties of ring _i

The φ that obtains for synchronization _S1And φ _S2, it comprises because the phase shift that pure rotation causes, and the phase shift that causes of various noise.

Can obtain the data of two output ports of different polarization states a moment simultaneously, analyze and obtain angular velocity of rotation.During this state, suppose to adopt above analytical approach to obtain containing the angular velocity of rotation Ω of different noises respectively from two polarization directions ₁And Ω ₂As shown in Figure 4, at a time, Ω ₁And Ω ₂Two-dimensional coordinate on, actual angular velocity of rotation value should be on 45 ° of lines.With a bit projecting on 45 ° of lines on the coordinate, pass through Ω ₁And Ω ₂Unite judgement, compare single Ω ₁Value can obtain angular velocity of rotation more accurately.

Utilize the dual-polarization optical fiber gyro structure of Fig. 2, can further explore and analyze the common noise characteristic, to reach the purpose of eliminating the noise item.

In the fibre optic gyroscope, thermonoise is an important noise source, and the Approximate Equivalent speed of rotation error that the thermal transient process causes is:

${\mathrm{\Ω}}_E\left(t\right)=\frac{1}{\mathrm{DL}}n\frac{\mathrm{dn}}{\mathrm{dT}}\underset{0}{\overset{L}{\∫}}\frac{\mathrm{dT}}{\mathrm{dt}}\left(z\right)(L-2z)\mathrm{dz}---\left(6\right)$

Wherein, D is the fiber optic loop diameter, and L is a fiber optic loop length, and T is a temperature, and n is an effective refractive index.

When using the different polarized light of two-way, can try to achieve φ respectively _1mAnd φ _2m,

φ _im＝2φ _0isin(ω _mτ _i/2)

＝2n _iΔlsin(ω _mn _iL/2c)

When the PZT modulator is operated in the pi/2 working point, sin (ω _mn _iL/2c) get maximal value, be in n _iChange insensitive zone.So φ _1m/ φ _2m=n ₁/ n ₂

Use temperature control circuit to regulate the PZT temperature, gather the interference light signal data, { the φ when finding the solution different temperatures _Im, obtain the n under the different temperatures ₁/ n ₂Value, thus extrapolate dn _iThe curve of/dT is determined because the two-way equivalence speed of rotation error ratio that temperature transient causes is

Be designated as ρ (T).Detailed process is as described in the embodiment of back.

Adopt modulation format 2, promptly on two branch roads flashlight is arranged all, establish the speed of rotation that obtains according to two paths of signals and be respectively Ω ₁And Ω ₂, real rotational speed is Ω, so

(Ω ₁-Ω)/(Ω ₂-Ω)＝ρ(T) (7)

Can instead solve with this: $\mathrm{\Ω}=\frac{{\mathrm{\Ω}}_1-\mathrm{\ρ}\left(T\right){\mathrm{\Ω}}_2}{1-\mathrm{\ρ}\left(T\right)}---\left(8\right)$

Like this,, can carry out Conjoint Analysis, reach more accurate angular velocity of rotation value to reduce influence for the noise that the temperature drift of two-way polarized light causes.This mode can be rejected the influence that temperature drift brings effectively, obtains angular velocity of rotation value accurately, and has guaranteed stability.

Other effects that cause noise have different forms with the relation of refractive index.If have difference power between the light wave of backpropagation in the fiber optic loop, will there be non-linear Kerr effect, a nonreciprocity phase differential that causes.Nonreciprocity refringence between the reverse light wave of this two-way is

${\mathrm{\Δn}}_k={\mathrm{\δn}}_{\mathrm{NL}1}-{\mathrm{\δn}}_{\mathrm{NL}2}=\frac{{\mathrm{\χ}}_e^{\left(3\right)}({\left|E^{\mathrm{cw}}\right|}^2-{\left|E^{\mathrm{ccw}}\right|}^2)}{2n}---\left(9\right)$

Wherein, χ _e ⁽³⁾Being three rank electric susceptibilities, is the main cause that causes third harmonic, four-wave mixing and nonlinear refractive index, | E ^Cw| ²With | E ^Ccw| ²It is respectively clockwise and counterclockwise light intensity.

For different polarization states, (n can be similar to and think the n difference $n=\sqrt{{\mathrm{\ϵ}}_r}=\sqrt{1+{\mathrm{\χ}}_e}$ )。The variation that temporary transient consideration is caused by Sagnac effect and non-linear Kerr effect, then

${\mathrm{\φ}}_1={\mathrm{\φ}}_s+{\mathrm{\Δn}}_1\·\mathrm{\φ}={\mathrm{\φ}}_s+\frac{{\mathrm{\χ}}_e^{\left(3\right)}({\left|E_1^{\mathrm{cw}}\right|}^2-{\left|E_1^{\mathrm{ccw}}\right|}^2)}{{2n}_1}\·\mathrm{\φ}$

${\mathrm{\φ}}_2={\mathrm{\φ}}_s+{\mathrm{\Δn}}_2\·\mathrm{\φ}={\mathrm{\φ}}_s+\frac{{\mathrm{\χ}}_e^{\left(3\right)}({\left|E_2^{\mathrm{cw}}\right|}^2-{\left|E_2^{\mathrm{ccw}}\right|}^2)}{{2n}_2}\·\mathrm{\φ}---\left(10\right)$

Wherein $\mathrm{\φ}=\frac{2\mathrm{\π}}{\mathrm{\λ}}L,$ (L refers to integration lengths here, and for wideband light source, this integration lengths is positioned at very short one section of coil mid point).

For the nonreciprocity effect that non-linear Kerr effect causes, phase interference item and the polarization state institute corresponding refractive index relation of being inversely proportional to be not so its signal processing method of taking just can be the same.Than temperature drift, the noise ratio that non-linear Kerr effect causes is less, so need (float as controlling temperature under at experiment condition, or adopt Kalman filtering to handle two tributary signals respectively and eliminate temperature and float, what obtain be respectively Ω on two branch roads eliminating temperature noise influence back _i'), consider to eliminate non-linear Kerr effect influence again.

Adopt amplitude modulation(PAM) sign indicating number type 2, promptly two branch roads all have flashlight, in the process that the experiment light path is built, record two-way light and close the extinction ratio δ that restraints to after the orthogonal optical on fast axle and the slow axis through bundling device, can extrapolate beam intensity ratio ξ=(1+ δ)/(the 1-δ) on fast axle and the slow axis.In equation (10),

$\mathrm{\ξ}=\frac{{\left|E_1^{\mathrm{cw}}\right|}^2-{\left|E_1^{\mathrm{ccw}}\right|}^2}{{\left|E_2^{\mathrm{cw}}\right|}^2-{\left|E_2^{\mathrm{ccw}}\right|}^2}$

Under the condition of modulation format 1, measured the n under the different temperatures in front ₁/ n ₂Value.Note η=ξ n ₂/ n ₁

Release the formula of similar (7) by equation (10):

(Ω ₁’-Ω’)/(Ω ₂’-Ω’)＝η (11)

Wherein, Ω ₁' and Ω ₂' be respectively two branch roads to be carried out angular velocity of rotation value after temperature is floated processing.

Thereby obtain Ω '=(η Ω ₂'-Ω ₁')/(η-1) (12)

For the noise that other factors cause, analyze the difference of its noisiness on fast and slow axis, finding algorithm pointedly just is to reduce The noise.

For thermal stress and vibration, the variation that this can cause the local birefringence rate causes the nonreciprocity biased error.Its noise error that causes is directly proportional with the variations in refractive index rate, can consider that following manner handles.

φ ₁＝φ _s+Δn ₁·φ (13)

φ ₂＝φ _s+Δn ₂·φ

Ω is easy to get _s=(Ω ₂Δ n ₁-Ω ₁Δ n ₂)/(Δ n ₁-Δ n ₂) (14)

But, need on statistical significance, carry out possible correction, or the factor that causes thermal stress and vibration of taking measures as far as possible to reduce to the result because thermal stress and vibration be difficult to determine.

Because the influence of cross polarization effect, high to the characteristic requirement of polarization-maintaining coupler in the light path, to forward and reverse, each polarization axle all will reach the extinction ratio of 30db.Therefore can consider depolarized scheme, both reduce, also can reduce the cost of polarization maintaining optical fibre the device property requirement.

The light channel structure of depolarized scheme as shown in Figure 5.

The power of two-way light can be different, carrying out different premodulation by two light paths behind the polarization-maintaining beam splitter, can be phase adjusted or amplitude adjusted promptly.

Good effect of the present invention is:

For dual-polarization optical fiber gyro scheme, carry out different amplitude sign indicating number type modulation, according to noisiness relevant with refractive index on the fast and slow axis, The noise is eliminated in Conjoint Analysis, to obtain angular velocity of rotation accurately.

Description of drawings

Fig. 1 is traditional single shaft polarization maintaining optical fibre gyro minimum reciprocal structure;

Fig. 2 is the double-polarization interference type optical fiber gyroscope structural drawing;

Fig. 3 is to dual-polarization light path amplitude modulation(PAM) sign indicating number type;

Fig. 4 is simple signal Processing schematic diagram;

Fig. 5 is the double-polarization interference type optical fiber gyroscope that adopts the depolarized structure of single mode.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail:

The present invention adopts ASE wide spectrum light source output signal light, becomes linearly polarized light behind the polarizer, and the polarization-maintaining coupler that adopts 50: 50 is as beam splitter.Amplitude premodulation on the two-way that is divided into adopts optical attenuator, and circuit is controlled the two-way attenuator state simultaneously, to reach required modulation format.Two kinds of amplitude modulation(PAM) sign indicating number types commonly used in experiment are: type 1---have only on the branch road has light signal to pass through to sign indicating number, and no light signal on another; Sign indicating number type 2---all there is light signal to pass through on two branch roads.Protect inclined to one side circulator and realize that forward is by (port one-＞port 2), oppositely by (port 2-＞port 3).Protect shift/beam splitter and the light polarization direction on the branch road can be rotated 90 °, and with two branch roads photosynthetic be the flashlight of quadrature on fast and the slow axis.50: 50 polarization-maintaining couplers with High Extinction Ratio are input to the polarization-maintaining fiber coil two ends with the flashlight of quadrature.

Port 3 at two circulators of reverse optical path is converted to electric signal to the interference light signal of different polarization states with photoelectric commutator, and gathers by the NI data collecting card.Utilize LabView that the data of gathering are carried out spectrum analysis and data storage.

Before experiment, want earlier to make having only that (as above branch road) has flashlight on the branch road by modulation format 1, by the temperature that temperature-control circuit is regulated PZT, store the interference signal luminous power of this branch road circulator port 3 after the PD conversion with data collecting card, utilize second harmonic B ₂With four-time harmonic B ₄Calculate corresponding { φ _1m; Under this temperature, making to have only has flashlight (following branch road) on another branch road, obtain { φ according to same step _2m.So just can obtain the n under the different temperatures ₁/ n ₂Value, and extrapolate dn _iThe curve of/dT.For the polarization property of entire system, need be at this modulation format 1 time, the signal data of circulator port 3 on another branch road of collection analysis.

When measuring the Sagnac effect, use modulation format 2, obtain two interference signal light signals on the branch road respectively, demodulation gets speed of rotation Ω ₁And Ω ₂After, utilize equation (8) to try to achieve Ω value more accurately.

The depolarizer that adopts in the depolarized structure of single mode can be the Lyot depolarizer of 45 ° of formation of polarization maintaining optical fibre deflection of 1: 2: 4 with three segment length ratio.Fiber optic loop adopts the general single mode fiber ring to get final product.Behind polarization-maintaining beam splitter, be divided into different polarization states in the reverse optical path, and carry out check and analysis.Because the various noises that two polarization states that are divided into experience in polarization-maintaining fiber coil more become identical with refractive index, its signal processing method has the need for further discussion.

Claims (9)

1. the united signal processing method of a double-polarization interference type optical fiber gyroscope, wherein said double-polarization interference type optical fiber gyroscope is:

Two linearly polarized light input light paths are protected shift/beam splitter through one and are connected with a coupling mechanism, and described coupling mechanism opposite side is connected with a fiber optic loop, are connected a phase-modulator between described fiber optic loop and the described coupling mechanism, the steps include:

1) modulation double-polarization interference type optical fiber gyroscope makes the two described linearly polarized light input light paths output signal light of property at interval;

2) measure described phase-modulator when different temperatures, the luminous power of exporting on the two described polarized light input light paths;

3), determine because the two-way equivalence speed of rotation error ratio that temperature transient causes according to the temperature value and the corresponding luminous power of record

N wherein ₁Be fast axle refractive index, n ₂Be the slow axis refractive index, T is a temperature;

4) modulation double-polarization interference type optical fiber gyroscope makes two described linearly polarized light input light paths output signal light simultaneously;

5) measure the luminous power of exporting on the two described linearly polarized light input light paths;

6) calculate speed of rotation Ω respectively according to step 5) institute photometry power ₁And Ω ₂

7) according to formula

Calculate revised rotational speed Ω.

2. the method for claim 1 is characterized in that described coupling mechanism is a polarization-maintaining coupler, and described fiber optic loop is a polarization-maintaining fiber coil.

3. method as claimed in claim 1 or 2 is characterized in that described linearly polarized light input light path comprises a signal modulator, and the linear polarization light source is connected with described guarantor's shift/beam splitter through described signal modulator.

4. method as claimed in claim 3 is characterized in that described linearly polarized light input light path comprises a circulator, and described signal modulator is connected with described guarantor's shift/beam splitter through described circulator, and described circulator is connected with a detector.

5. method as claimed in claim 4 is characterized in that described signal modulator is a phase-modulator.

6. method as claimed in claim 4 is characterized in that described signal modulator is an amplitude modulator.

7. method as claimed in claim 1 or 2 is characterized in that described ratio

Computing method be: at first the expression formula of interference signal luminous power is launched according to Bessel's function; Then according to step 2) luminous power surveyed, utilize that wave filter takes out wherein one, two, the amplitude of four-time harmonic; Then according to extracted one, two, φ when the amplitude of four-time harmonic solves different temperatures _Im, φ wherein _Im=2 φ _0iSin (ω _mτ _i/ 2); Obtain the n under the different temperatures at last ₁/ n ₂Value, thus extrapolate dn _iThe curve of/dT is determined described ratio ρ (T); I=1 or 2 wherein, during i=1 corresponding to fast axle, during i=2 corresponding to slow axis.

8. method as claimed in claim 1 or 2 is characterized in that adopting kalman filter method to handle the signal of two described linearly polarized light input light paths respectively, eliminates temperature and floats, and obtains the speed of rotation Ω on two branch roads ₁' and Ω ₂'; Then according to formula Ω '=(η Ω ₂'-Ω ₁')/(η-1) calculate revised speed of rotation Ω ', η=ξ n wherein ₂/ n ₁,

| E _i ^Cw| ²Be clockwise light intensity, | E _i ^Ccw| ²Be counterclockwise light intensity, i=1 or 2, during i=1 corresponding to fast axle, during i=2 corresponding to slow axis.

9. method as claimed in claim 1 or 2 is characterized in that utilizing formula Ω _s=(Ω ₂Δ n ₁-Ω ₁Δ n ₂)/(Δ n ₁-Δ n ₂) calculate revised speed of rotation Ω _s, Δ n wherein ₁For causing that by stress or vibration fast axle local indexes of refraction changes Δ n ₂For causing that by stress or vibration the slow axis local indexes of refraction changes.

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