Background technique
As navigation, the typical case of the important sensing unit in guidance field and reciprocity effect, gyroscope is exclusive with its
Advantage is widely used.Relative to tradition machinery gyro, optical fibre gyro has the advantages such as light weight, small in size, electromagnetism interference.
Sensing element --- the stability and reliability of the manufacture craft of optical fibre gyro ring will directly affect optical fiber top to key therein
Spiral shell overall mass and navigation accuracy.According to Sagnac (Sagnac) effect, it is understood that positive transmission light in optical fibre gyro ring
With reverse transfer light, need just to can be carried out accurate navigation by identical light path information.1980, the human hairs such as Shupe
The variation of temperature can cause the nonreciprocity of optical fibre gyro in present environment, so as to cause biggish gyroscopic drift.Optical fiber top
In loop coil an important factor for the light path inconsistency, referred to as influence fiber optic gyroscope performance of positive transmission light and reverse transfer light.
On how to reduce optical fibre gyro ring nonreciprocal effect caused by heat, it has been proposed that more solution.
2012, Song Ningfang of BJ University of Aeronautics & Astronautics et al. disclosed a kind of intersection coiling light symmetrical above and below for optical fibre gyro
Fine gyro ring structure (Chinese Patent Application No.: 201210043894.3).Fiber optic coils are divide into upper part and lower part, and have side
Without structural constraint, will not be squeezed under conditions of vibration is with temperature change;By intersecting, two lateral coils contain identical length
Forward and reverse optical fiber of degree, so that the axial temperature modulation generated with radial temperature gradient to optical fiber is equal.Optical fibre gyro
The symmetrical winding method of ring improves the transient response of its Direct/Reverse to a certain extent.However, optical fibre gyro ring about around
The slight asymmetry of fiber optic hub point processed will largely weaken the advantage of symmetrical winding.2012, Beijing Aviation
The Yang Dewei et al. of space flight university discloses a kind of estimation of optical fibre gyro ring polarization crosstalk and symmetry evaluation method (Chinese patent
Application number: CN201210359805.6).While measuring optical fibre gyro ring polarization coupled intensity distribution, length scanning is utilized
Method obtains the birefringence dispersion coefficient of testing fiber, establishes polarization crosstalk estimation model, judges optical fibre gyro ring midpoint, obtain
Point left and right sides polarization crosstalk data, using polarization crosstalk value as evaluation optical fibre gyro around the reference index of symmetry processed.The hair
The bright coiling for being applied to measure a variety of polarization maintaining optical fibres, is convenient for optimum choice gyro materials optical fiber, to assessment and guidance optimization optical fiber
The temperature performance of gyro is significant.
Light coherent field polarization technology (OCDP) is a kind of extremely superior distributed measurement technology.He passes through scan-type optics
Interferometer carries out optical path compensation, realizes the interference between different coupled mode, can position the position of winding optical fiber internal flaw, utilizes
The polarization coupled intensity of interference strength analyzing defect point.2011, Yang Jun of Harbin Engineering University et al. disclosed one kind and mentions
High polarization maintaining optical fibre polarization coupled measurement accuracy and symmetry device and method (Chinese Patent Application No.:
201110118450.7).By the controllable reversing mechanism of optical signal, it can be achieved that testing fiber gyro ring difference forward and reverse is surveyed
Amount.The present invention provides a kind of influences that can reduce birefringence dispersion to measurement accuracy, the parameter measurement for optical fibre gyro ring
There is very important practical value with performance evaluation.In the same year, it is a kind of that Yang Jun of Harbin Engineering University et al. is provided again
Reduce birefringence dispersion on polarization maintaining optical fibre polarization coupled measurement influence device (Chinese Patent Application No.:
CN201110118127.X).The present invention polarizes polarization apparatus using a half-reflection and half-transmission, and wide spectrum optical is divided into two beams, realizes
Simultaneously from positive and inversely can obtain scan position simultaneously using same polarization coupled detection device by testing fiber
Symmetrical two width polarization coupled measurement data.
However, although measurement method mentioned above can be realized positive, reversed measurement or evaluate optical fibre gyro
Symmetry: the Wavelength Scanning Method of Song Ningfang et al. has only measured the one of the left and right side section polarization coupled of optical fibre gyro ring
A average value has no idea to realize distributed measurement;The controllable reversing mechanism of Yang Jun et al. is not carried out simultaneity, can not exclude
The inconsistent bring of the environmental parameters such as temperature when Time Inconsistency influences;Although half-reflection and half-transmission polarization polarization apparatus realizes simultaneously
Property, but it is complete same paths that positive, reverse measuremenet, which is not,.These schemes based on OCDP technology, lack it is certain can
Row, online real-time monitoring effect substantially reduce, and also lack effectively evaluating mark in the full temperature characteristics of analysis optical fibre gyro ring
It is quasi-.Therefore, it is necessary to a kind of new methods to evaluate the symmetry of optical fibre gyro ring and around ring quality, selection to materials optical fiber and
Improvement around ring technique provides effective monitoring and necessary guidance in real time.
Summary of the invention
It is right the purpose of the present invention is to propose to a kind of qualitative assessment for realizing the polarization coupled to optical fibre gyro ring and symmetry
The forward and reverse of optical fibre gyro ring carries out while the symmetry of the optical fibre gyro ring polarization coupled of measurement assesses device.
The object of the present invention is achieved like this:
A kind of symmetry assessment device of optical fibre gyro ring polarization coupled, including light supply apparatus 10, test device 11, first
Light path correlator 12A, the second light path correlator 12B, difference detecting device 13, photoelectric signal transformation and signal recording apparatus 14.
Include in test device 11 device under test 110, the 1st circulator 113A that is connected with 110 both ends of device under test and
2nd circulator 113B, the 1st polarizer 111A and the 1st analyzer 111B, the 2nd polarizer 112A and the 2nd analyzer 112B;
1st circulator 113A and the 2nd circulator 113B physical parameter having the same, the both ends difference of device under test 110
It is connect with the 2nd port of the 1st circulator 113A and the 2nd circulator 113B;1st polarizer 111A and the 2nd polarizer 112A have
Identical to be polarized angle, the two is connect with the 1st port of the 1st circulator 113A and the 2nd circulator 113B respectively;1st analyzer
111B and the 2nd analyzer 112B analyzing angle having the same, the two respectively with the 1st circulator 113A and the 2nd circulator 113B
The 3rd port connection;
Wide spectrum light source 101 arrives test device 11 via the 1st averagely light splitting of coupler 103;Two-beam is respectively via device to be measured
The both ends of part 110 input, while generating two groups of positive, reversed signals;It is related by the first light path correlator 12A, the second light path
Device 12B is scanned;The symmetrical polarization coupled signal of two width scan positions is finally exported, is realizing device under test 110 just
To, reversely test simultaneously.
Wide spectrum light source 101 in light supply apparatus 10 is carried out via the 1st averagely light splitting of coupler 103 into test device 11
Polarization coupled test;Calibration light source 102 in light supply apparatus 10 is via the 2nd coupler 104 averagely light splitting to the first light path correlation
Position correction is scanned in device 12A, the second light path correlator 12B;
1st light path correlator 12A is saturating by the 3rd coupler 121A, the 4th coupler 122A, the 3rd circulator 123A, the 1st collimation
Mirror 124A and scan table 125 form;Wide spectrum light source 101 passes through the 2nd inspection via the device in device under test 110 and test device 11
Inclined device 112B and the connection of the 3rd coupler 121A input terminal;Calibration light source 102 passes through the 2nd coupler 104 and the 3rd coupler 121A
The connection of another input terminal;Two output ends of 4th coupler 122A are visited with the first differential detector 130A, the second difference respectively
Survey device 130B connection;Data acquisition is carried out by data collecting card 141, host computer 142 is transferred to and exports polarization coupled signal;
2nd light path correlator 12A and the 1st light path correlator 12A is in addition to sharing scan table 125, the physics ginseng of other devices
Number is corresponding consistent.
The 1st circulator 113A and the 2nd circulator 113B, is three port devices, and light is only propagated in one direction;Letter
If number from the 1st port 71A input, can only be exported from the 2nd port 71B;And signal is inputted from the 2nd port 71B, then it can only the 3rd
Port 71C output;Conversely, can not transmit.
Include in test device 21 device under test 110, the forward coupler 214A that is connected with 110 both ends of device under test and
Reverse coupler 214B, the 1st polarizer 111A and the 1st analyzer 111B, the 2nd polarizer 112A and the 2nd analyzer 112B, the 1st
Isolator 213A and the 2nd isolator 213B;
The both ends of device under test 110 are connect with one end of forward coupler 214A and reverse coupler 214B respectively;1st every
It is another with forward coupler 214A and reverse coupler 214B respectively from the output port 72B of device 213A and the 2nd isolator 213B
One end connection;1st polarizer 111A and the 2nd polarizer 112A is having the same to be polarized angle, the two respectively with the 1st isolator
The input port 72A connection of 213A and the 2nd isolator 213B;1st analyzer 111B and the 2nd analyzer 112B inspection having the same
Inclination angle, the two are connect with the other end of forward coupler 214A and reverse coupler 214B respectively.
The 1st isolator 213A or the 2nd isolator 213B are inputted from the 1st port, are exported from the 2nd port, light can only
It propagates, otherwise can not transmit in one direction.
The beneficial effects of the present invention are:
1. can be achieved at the same time the forward and reverse measurement of the polarization coupled information of the defect point of optical fibre gyro ring, it is suppressed that
Optical fibre gyro ring symmetric points dispersive influence inconsistency bring measurement error, the structure are simple and effective;
2. reducing the testing time of optical fibre gyro ring polarization coupled measuring device, measurement efficiency is high, eliminates the rings such as temperature
The influence of border factor;
3. the polarization coupled symmetry of optical fibre gyro ring can be obtained accurately.Since forward and reverse can be carried out simultaneously
Measurement, can obtain two width of polarization maintaining optical fibre about the symmetrical distributed polarization coupling measurement result in midpoint simultaneously.
Specific embodiment
The following further describes the present invention in combination with the embodiments and the accompanying drawings.
The invention proposes a kind of symmetry of optical fibre gyro ring polarization coupled to assess device.It is characterized in that device is used
White light source be divided into two beams;The forward direction for being injected separately into testing fiber gyro ring using having directive optical device
With it is reversed;Then two sets of relatively independent interferometers for sharing same scan table are scanned;It is finally inclined using optical coherence domain
Vibration measuring technique, while obtaining the symmetrical two width polarization coupled measurement data of scan position.Present apparatus structure is simple, measurement accuracy
Height can reduce the influence that birefringence dispersion measures polarization maintaining optical fibre polarization coupled.Polarization of the present invention for optical fibre gyro ring
Coupling measurement and symmetrical Performance Evaluation have important practical value, can be used for improving optical fibre gyro ring technique for coiling and optimization light
Fine gyro production process.
Device includes light supply apparatus 10, test device 11, light path correlator 12A and 12B, difference detecting device 13, photoelectricity
Signal conversion and signal recording apparatus 14, it is characterized in that:
(1) the 1st circulator 113A for including device under test 110 in test device 11, being connected with 110 both ends of device under test
With the 2nd circulator 113B, the 1st polarizer 111A and the 1st analyzer 111B, the 2nd polarizer 112A and the 2nd analyzer 112B.
(2) the 1st circulator 113A and the 2nd circulator 113B physical parameter having the same, the both ends point of device under test 110
It is not connect with the 2nd port 71B of the 1st circulator 113A and the 2nd circulator 113B;1st polarizer 111A and the 2nd polarizer 112A
It is having the same to be polarized other physical parameters such as angle, the two respectively with the 1st circulator 113A and the 2nd circulator 113B the 1st
Port 71A connection;Other physical parameters such as the 1st analyzer 111B and the 2nd analyzer 112B analyzing angle having the same, the two
It is connect respectively with the 3rd port 71C of the 1st circulator 113A and the 2nd circulator 113B.
(3) wide spectrum light source 101 arrives test device 11 via the 1st averagely light splitting of coupler 103;Two-beam is respectively via to be measured
The both ends of device 110 input, while generating two groups of positive, reversed signals;By two sets it is relatively independent, share scan table 125
Light path correlator 12A and 12B be scanned;Finally export the symmetrical polarization coupled signal 143A of two width scan positions and
143B, realize device under test 110 it is positive, reversely test simultaneously.
A kind of symmetry of optical fibre gyro ring polarization coupled assesses device, it is characterized in that:
(1) wide spectrum light source 101 in light supply apparatus 10, via the averagely light splitting of the 1st coupler 103 into test device 11 into
The test of row polarization coupled;Calibration light source 102 in light supply apparatus 10 is via the 2nd coupler 104 averagely light splitting to two light path phases
It closes in device 12A and 12B and is scanned position correction.
(2) the 1st light path correlator 12A are by the 3rd coupler 121A, the 4th coupler 122A, the 3rd circulator 123A, the 1st standard
Straight lens 124A and scan table 125 form;Wide spectrum light source 101 is via the related device in device under test 110 and test device 11
It is connected by the 2nd analyzer 112B and the 3rd coupler 121A input terminal;Calibration light source 102 passes through the 2nd coupler 104 and the 3rd coupling
The connection of another input terminal of clutch 121A;Two output ends of 4th coupler 122A respectively with differential detector 130A and 130B
Connection;Data acquisition is carried out by data collecting card 141, host computer 142 is transferred to and exports polarization coupled signal 143A and 143B.
(3) the 2nd relatively independent light path correlator 12A and the 1st light path correlator 12A in addition to share scan table 125, other
The physical parameter of device is corresponding consistent.
The circulator 113A or 113B, is three port devices, and light can only be propagated in one direction.If signal is from the 1st
Port 71A input, then can only export from the 2nd port 71B;And signal is inputted from the 2nd port 71B, then it will be defeated from the 3rd port 71C
Out;Conversely, can not transmit.
A kind of symmetry of optical fibre gyro ring polarization coupled assesses device, it is characterized in that:
(1) forward coupler for including device under test 110 in test device 21, being connected with 110 both ends of device under test
214A and reverse coupler 214B, the 1st polarizer 111A and the 1st analyzer 111B, the 2nd polarizer 112A and the 2nd analyzer
112B, the 1st isolator 213A and the 2nd isolator 213B.
(2) both ends of device under test 110 are connect with one end of forward coupler 214A and reverse coupler 214B respectively;The
The output port 72B of 1 isolator 213A and the 2nd isolator 213B is respectively with forward coupler 214A's and reverse coupler 214B
Other end connection;1st polarizer 111A and the 2nd polarizer 112A is having the same to be polarized other physical parameters such as angle, the two
It is connect respectively with the input port 72A of the 1st isolator 213A and the 2nd isolator 213B;1st analyzer 111B and the 2nd analyzer
Other physical parameters such as 112B analyzing angle having the same, the two respectively with forward coupler 214A and reverse coupler 214B
The other end connection.
The isolator 213A or 213B of a kind of optical fibre gyro ring polarization coupled are inputted from the 1st port 72A, from the 2nd
Port 72B output, light can only be propagated in one direction, otherwise can not transmit.
Generally, traditional optical fibre gyro ring polarization coupled measuring device is as shown in Fig. 4.To discontinuous in polarization maintaining optical fibre
Point polarization coupled assessment, using optical coherence domain polarization measurement device.The light that wide spectrum light source (SLD) 101 issues successively leads to
Polarizer 411A, device under test 110, analyzer 411B are crossed, is connect with Mach Zehnder interferometer (MZI) 42, and then connects difference
Detection device 43 is finally detected with interference signal and is connect with processing unit 14;In addition, calibration light source 102 is dry for Mach Zehnder
The displacement correction of displacement platform 425 in interferometer 42;Data acquisition is carried out by data collecting card 441, is transferred to the output of host computer 442
Polarization coupled signal 442 only includes the positive information of device under test 110.
The symmetry assessment device of optical fibre gyro ring polarization coupled mentioned in the present invention is from positive, reversed simultaneously to guarantor
Simultaneously respectively measurement is primary for the polarization coupled of polarisation fibre.If attached drawing 5 is the simplification optical path scheme that its two-way simultaneous measures.Assuming that
Survey device 110 is panda type polarization-preserving fiber, and length L, wherein the refractive index of slow axis is nslow, the refractive index of fast axle is nfast, then
The refringence of the fast and slow axis of polarization maintaining optical fibre is Δ n=nslow-nfast.Assuming that transmission light is inputted from slow axis, apart from device under test
110 head end x distance and positions have a defect point.At head end x polarised light can couple, a small amount of transmission light is from slow axis
It is coupled in fast axle.
In forward direction measurement and reverse measuremenet path, the light path that the transmission light not coupled is passed by is represented by
STransmission=nslowL, (1)
In positive measuring route, the light path 51 that coupling light is passed by can be expressed as
SCoupling _ forward direction=nslow x+nfast(L-x), (2)
In reverse measuremenet path, the light path 52 that coupling light is passed by can be expressed as
SCoupling _ forward direction=nslow(L-x)+nfast x。 (3)
Forward direction is measured, by formula (1) and (2) it is found that the optical path difference of transmission light and coupling light is
ΔSIt is positive=Δ n (L-x), (4)
For reverse measuremenet, by formula (1) and (3) it is found that the optical path difference of transmission light and coupling light is
ΔSReversely=Δ nx. (5)
In figure 5, about symmetrical two defect points of 53 (length L/2) of optical fibre gyro ring midpoint --- near head end
(the length x of defect point 541) and (the length x of caudal part defect point 552), that is, there is following relationship
L/2-x1=x2-L/2。 (6)
Generally, other than such environmental effects, the dispersive influence in optical fiber is with length correlation.When forward direction measurement, pass through
The coupling light of the near head end defect point 54 of testing fiber and the optical path difference for transmitting light, it is longer than experience caudal part defect point 55, because
This dispersion is affected near head end defect point 54.
At this point, according to formula (4) and formula (6), transmitting light and coupling when measuring near head end defect point 54 using forward direction
The optical path difference of light combination is
ΔSIt is positive=Δ n (L-x1), (7)
When for caudal part defect point 55 using reverse measuremenet, according to formula (5) and formula (6), light and coupling light are transmitted
Optical path difference be
ΔSReversely=Δ nx2=Δ n (L-x1)。 (8)
By formula (7) and formula (8) it is found that in above-mentioned optical path scheme, forward and reverse simultaneously measure obtain about
The location information of polarization coupled point is symmetrical about optical fiber midpoint.Dispersion in optical fiber is for optical fibre gyro ring central symmetry
The influence of defect point is mesh that is the same, i.e., can not only being reached while be measured using polarization coupled measuring device proposed by the present invention
, dispersion bring influences when also eliminating measurement.
Application Example 1
Measuring device is as shown in Fig. 1, and device parameters selection is as follows:
(1) the central wavelength 1550nm, half spectral width 45nm of wideband light source 101, fiber power are greater than 5mW, and extinction ratio is big
In 6dB;
(2) testing fiber device 110 is 500m panda type polarization-preserving fiber;
The operation wavelength of (3) the 1st polarizer 111A, the 1st analyzer 111B, the 2nd polarizer 112A and the 2nd analyzer 112B
For 1550nm, extinction ratio is greater than 20dB, and insertion loss is less than 3dB;
(4) the 1st circulator 113A and the 2nd circulator 113B be three port polarization-maintaining circulators, other circulators 123A and
123B is the belt device of three port single mode optical fibers, and return loss is greater than 55dB, and insertion loss is less than 1dB;
(5) fiber coupler 103,104, the operation wavelength of 121A, 121B, 122A, 121B are 1310/1550nm, light splitting
Than 50:50, insertion loss is less than 0.5dB;
(6) operation wavelength of collimation lens 124A and 124B is 1550nm;
(7) diameter of reflecting mirror used is 20mm in displacement platform 125, and average reflectance is greater than 95%.
In summary condition, measures that polarization coupled signal is as shown in Fig. 6, and wherein attached drawing 6 (a) and 6 (b) is respectively 500m
Optical fibre gyro ring forward direction measurement result and reverse measuremenet result.For the sake of simplicity, we are respectively lacked with 3 typical cases of head end and tail end
It is analyzed for polarization coupled peak caused by trapping spot.Characteristic peak 61,62,63 respectively corresponds in attached drawing 6 (b) in attached drawing 6 (a)
Characteristic peak 61 ', 62 ', 63 ', in attached drawing 6 (a) characteristic peak 64,65,66 respectively correspond characteristic peak 64 ' in attached drawing 6 (b), 65 ',
66'.The characteristic peak due to caused by optical fibre gyro ring head end (such as 64,65,66) is due to larger by dispersive influence, peak value broadening
Amplitude reduces, and large error can be caused compared with characteristic peak caused by tail end.Correspondingly, if with the respective scanned in attached drawing 6 (b)
The characteristic peak of optical path difference position compares, and the symmetry information of optical fibre gyro ring can be obtained.
Application Example 2
Measuring device is as shown in Fig. 7, other than 11 difference of test device in test device 71 and attached drawing 1, remaining part
It is divided to two devices essentially identical.
(1) the 1st circulator for including device under test 110 in test device 71, being connected with device under test (110) both ends
113A and the 2nd circulator 113B, the polarizer 710, coupler 711, the 1st analyzer 111B, the 2nd analyzer 112B.
(2) the 1st circulator 113A and the 2nd circulator 113B physical parameter having the same, the both ends point of device under test 110
It is not connect with the 2nd port of the 1st circulator 113A and the 2nd circulator 113B;Two output ends of coupler 711 are respectively with the 1st
The connection of the 1st port of circulator 113A and the 2nd circulator 113B, the input terminal of coupler 711 are connect with the polarizer 710;1st inspection
Inclined other physical parameters such as device 111B and the 2nd analyzer 112B analyzing angle having the same, the two respectively with the 1st circulator
The connection of the 3rd port of 113A and the 2nd circulator 113B.
(3) wide spectrum light source 101 is connect with 710 input terminal of the polarizer in test device 71;Via the two of device under test 110
End generates two groups of positive, reversed signals simultaneously, by two sets of relatively independent, shared scan tables 125 light path correlator 12A and
12B is scanned;Two width scan positions opposite polarization coupled signal 143A and 143B are finally exported, realizes device under test
110 it is positive, reversely test simultaneously.
Device parameters selection is similar with Application Example 1, passes through measurement, available attached drawing 6 identical polarization coupled letter
Number.