CN104864911B - High-speed demodulating apparatus and method based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating - Google Patents
High-speed demodulating apparatus and method based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating Download PDFInfo
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Abstract
The present invention is a kind of high-speed demodulating apparatus based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating and method.High-speed demodulating apparatus includes light source module, three-dB coupler, circulator, sensing unit and demodulating unit.High speed demodulation method includes：By demarcating the relation between the demodulating error amount and temperature variation, pressure/strain variation amount that obtain fiber grating, demarcation obtains the relation between the change of cavity length amount and temperature variation, pressure/strain variation amount of Fabry-perot optical fiber chamber；Demodulate the drift value of the change of cavity length amount of Fabry-perot optical fiber chamber and the reflection kernel wavelength of fiber grating；Try to achieve temperature variation and pressure/strain variation amount.Compared with prior art, the present invention is on the basis of based on Fabry-perot optical fiber chamber and optical fiber grating sensing, the measurement of double parameters can be realized by fast demodulation, while compensate for because Fabry-perot optical fiber interference spectrum is to the influence to temperature survey caused by demodulating fiber bragg grating, and realize that the cost of this programme is low.
Description
Technical field
The present invention relates to technical field of optical fiber sensing, more particularly to one kind is based on the double parameters of Fabry-perot optical fiber chamber and fiber grating
The high-speed demodulating apparatus and method of combined measurement.
Background technology
In recent years, based on fibre optical sensor double parameters (temperature, pressure/strain) at the same sensing technology be one very
Active research field, this kind of sensing is mainly used in composite, heavy construction structure, aerospace vehicle, war products etc.
Structural health self diagnosis, environment self-adaption, damage self-healing etc..
Fabry-perot optical fiber chamber is the change that external physical quantity is obtained by demodulating chamber length as sensor, and it has structure letter
The advantages of list, small volume, easy for installation, high reliability, high sensitivity, quick response, monochromatic light optical fiber signaling are transmitted, passes as optical fiber
One of sense technology and the focus of application study.The drift value realization pair that fiber grating passes through demodulating fiber bragg grating reflection kernel wavelength
Detection to be measured, its sourceless characteristic, electromagnetism interference, corrosion-resistant and temperature tolerance etc. cause fiber grating is adapted to severe at some
Health monitoring is carried out in environment.In recent years, Fabry-perot optical fiber chamber was combined with the characteristic of fiber grating, and realized that double parameters were surveyed
Amount, has received the concern of scholars.
In the prior art, [such as document 1 in the technology demodulated to Fabry-perot optical fiber chamber and fiber grating composite sensing：Rao Yunjiang,
Zeng Xiangkai, Zhu Yong etc., extrinsic Fabry-Perot interferometer optical fibre Bragg optical grating strain temperature sensor and its application
[J] Acta Opticas, 2002,22 (1):85-88；Document 2：Baochen Sun,Liping Yang,Yanliang Du,et
al.Research on integrated fibre Bragg grating/extrinsic Fabry-Perot sensor
[C],Proceedings of the 6th World Congress on Intelligent Control and
Automation,Dalian,China,2006；], it is general to use spectrometer scanning optical spectrum, by observing spectral information, utilize phase
Position demodulation method is demodulated to the chamber length of Fabry-perot optical fiber chamber, directly observes the amount of movement of fiber bragg grating center wavelength in spectrum to light
Fine optical grating reflection centre wavelength is demodulated.Existing this demodulation mode, demodulation speed is slow, it is impossible to meet wanting for fast demodulation
Ask.
The content of the invention
For existing demodulation speed it is slow the problem of, the invention provides one kind based on the double ginsengs of Fabry-perot optical fiber chamber and fiber grating
Measure the high-speed demodulating apparatus and method of combined measurement.The high-speed demodulating apparatus and method of double parameter combined measurements of the present invention, are fitted
, can be real to temperature, pressure in environment/strain variation for the measurement based on Fabry-perot optical fiber chamber and optical fiber Bragg grating sensing
Now quick measurement.
A kind of high-speed demodulating apparatus based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating that the present invention is provided,
Including：Light source module, three-dB coupler, circulator, sensing unit and demodulating unit.
The light source module includes three narrow-band light sources and wide spectrum light source, the spectrum of three narrow-band light sources and wide spectrum light source
Spectrum non-overlapping copies；The sensing unit includes Fabry-perot optical fiber chamber sensing arrangement and optical fiber grating sensing structure；The demodulation is single
Member includes 1 × 3 dense wave division multiplexer (DWDM), 1 × 2 Coarse Wave Division Multiplexer (CWDM), photodetector, signal condition electricity
Road, data collecting card and computer.
The three beams laser of narrowband sent in light source module is with a branch of wide spectrum optical by four single-mode fiber simultaneous transmissions to 4 × 1
Three-dB coupler after, four bundles light is coupled to be incided in circulator, then incoming sensing unit.
The optical signal of incoming sensing unit is first incident to enter optical fiber grating sensing structure, meets fiber grating reflection kernel ripple
Long light wave is reflected, and other light-wave transmissions enter Fabry-perot optical fiber chamber sensing arrangement and multiple-beam interference occurs wherein, interfere
Light returns to optical fiber grating sensing structure and directly transmitted by it, and interference light is superimposed spectrum with the reflected light formation of fiber grating.
Spectrum is superimposed incident into 1 × 3DWDM and 1 × 2CWDM respectively by 1 × 2 three-dB coupler, by optical signal point
For five tunnels.1 × 3DWDM matches with three narrow-band light sources, and the three-beam exported by 1 × 3DWDM is used to demodulate Fabry-perot optical fiber chamber
Chamber it is long；The two-beam of 1 × 2CWDM outputs is used for the demodulation of fiber grating reflection kernel wavelength.Five road optical signals are visited through photoelectricity
Survey device to be converted to electric signal and enter signal condition unit, electric signal is changed into data signal by data by signal condition unit
Capture card is transferred to computer and stored.Electric signal is demodulated in a computer, the chamber length for obtaining Fabry-perot optical fiber chamber becomes
The drift value of change amount and fiber grating reflection kernel wavelength.
The sensing unit is the compound sensor of the fiber grating composition of Fabry-perot optical fiber chamber and Non-stress packaging, either
The cascaded structure of Fabry-perot optical fiber pressure/strain transducer and fiber-optical grating temperature sensor.
Requirement according to demodulation to light source, the narrow-band light source is Distributed Feedback Laser, and the wide spectrum light source uses Amplified Spontaneous
Radiating light source (ASE) or the super-fluorescence light source (SFS) based on doped fiber.
Based on above-mentioned high-speed demodulating apparatus, present invention also offers one kind based on the double ginsengs of Fabry-perot optical fiber chamber and fiber grating
Measure the high speed demodulation method of combined measurement, including step in detail below：
Step one：Calibration experiment is carried out, error drift amount Δ λ caused by demodulating fiber bragg grating reflection kernel wavelength is obtained1
With the relation between variation of ambient temperature amount Δ T, pressure/strain variation amount Δ X, it is as follows：
Δλ1=K1ΔT+K2ΔX (1)
Obtain the change of cavity length amount Δ L and variation of ambient temperature amount Δ T of Fabry-perot optical fiber chamber, pressure/strain variation amount Δ X it
Between relation：
Δ L=K3ΔT+K4ΔX (2)
Step 2：Demodulate the drift value of the change of cavity length amount of Fabry-perot optical fiber chamber and the reflection kernel wavelength of fiber grating；
The change of cavity length amount Δ L of Fabry-perot optical fiber chamber is obtained by the digital phase demodulating method demodulation of three wavelength, passes through edge
Filter method demodulates the drift value Δ λ for obtaining fiber grating reflection kernel wavelength；Wherein, Δ λ contains fiber grating reflection kernel
The demodulating error drift value Δ λ of wavelength1With practical center wavelength shift Δ λ of the fiber grating caused by temperature change2,
The actual drift value Δ λ of fiber grating reflection kernel wavelength2It is represented by：
Δλ2=Δ λ-Δ λ1 (3)
Step 3：Solve temperature variation Δ T and pressure/strain variation amount Δ X
Utilize formula (1), (2), (3), and integrated temperature variation delta T and the actual drift value of fiber bragg grating center wavelength
Δλ2Between relation, obtain temperature variation Δ T and be represented by：
The variation delta X of pressure/strain is：
In formula (4), (5), A is the temperature sensitive coefficient of fiber grating.Temperature in environment is finally obtained using formula (4), (5)
With the variable quantity of pressure/strain.
The invention has the advantages that：The fast advantage of demodulation speed of the invention based on intensity demodulation, is completed double
Parameter (temperature, pressure/strain) is while the demodulating equipment and the design of method that quickly measure so that double parameters can be surveyed quickly simultaneously
Amount；On the other hand, by calibration experiment, compensate for due to Fabry-perot optical fiber chamber return interference spectrum to demodulating fiber bragg grating to temperature
Measure the influence caused so that measurement result is more accurate；Demodulation scheme is avoided using tradition based on Fabry-perot optical fiber chamber and optical fiber light
The high spectrometer of price required for grid two parameter measurement so that demodulation cost is greatly reduced.
Brief description of the drawings
Fig. 1 is the high-speed demodulating apparatus structure based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating of the invention
Schematic diagram；
Fig. 2 is superimposed spectrum schematic diagram for the emulation that wide spectrum optical in the present invention is returned through Fabry-perot optical fiber chamber after fiber grating；
The demodulating error drift value and temperature variation for the demarcation optical fiber optical grating reflection centre wavelength that Fig. 3 provides for the present invention
Between relation experimental provision schematic diagram；
When Fig. 4 is no pressure/effects of strain, the spectrum that is superimposed that wide spectrum optical is returned through Fabry-perot optical fiber chamber after fiber grating exists
Emulation superposition spectrogram before and after variation of ambient temperature；
The demodulating error drift value for the demarcation optical fiber optical grating reflection centre wavelength that Fig. 5 provides for the present invention and pressure/strain
The experimental provision schematic diagram of relation between variable quantity；
When Fig. 6 is without temperature change, what wide spectrum optical was returned through Fabry-perot optical fiber chamber after fiber grating is superimposed spectrum in environment
Emulation superposition spectrogram before and after pressure/strain variation；
When Fig. 7 is without temperature change, what wide spectrum optical was returned through Fabry-perot optical fiber chamber after fiber grating is superimposed spectrum in environment
The detailed schematic of fiber grating part in emulation superposition spectrogram before and after pressure/strain variation；
The change of cavity length amount and temperature variation, pressure/strain variation for the demarcation Fabry-perot optical fiber chamber that Fig. 8 provides for the present invention
The experimental provision schematic diagram of relation between amount；
Fig. 9 is the experimental provision schematic diagram of demarcation optical fiber grating temperature sensitivity in the present invention.
Wherein：
1- light source modules, the Distributed Feedback Lasers of 2- first, the Distributed Feedback Lasers of 3- second, the Distributed Feedback Lasers of 4- the 3rd, 5- wide spectrum opticals
Source, 6- single-mode fibers, the three-dB coupler of 7-4 × 1,8- circulators, the three-dB coupler of 9-1 × 2,10- optical fiber grating sensing knots
Structure, 11- Fabry-perot optical fiber chamber sensing arrangements, 12- sensing units, 13-1 × 3DWDM, 14-1 × 2CWDM, 15- photodetectors,
16- signal conditioning circuits, 17- data collecting cards, 18- computers, 19- demodulating units, 20- fiber grating reflectance spectrums, 21- optical fiber
Fa-Po cavity interference spectrum, 22- temperature loading devices, the 23- joints of optical fibre, 24- ring flanges, 25- spectrometers, 26- pressure/strain adds
Carry and put, 27- temperature, pressure/strain loading device, 28-SM125 (FBG) demodulators.
Embodiment
The embodiment of the present invention is described in detail below in conjunction with accompanying drawing.
The present invention is by sensory-perceptible ambient temperature, the change of pressure/strain, by the chamber for demodulating Fabry-perot optical fiber chamber simultaneously
The reflection kernel wavelength shift of long variable quantity and fiber grating, realizes the measurement to temperature, pressure/strain variation amount.This hair
It is bright to be integrated in the digital phase demodulating method of three wavelength based on intensity demodulation in a set of demodulation scheme with edge filter method, it is right respectively
Fabry-perot optical fiber chamber and fiber grating are demodulated, and no longer by the way of spectral scan, so substantially increase the speed of demodulation
Degree.On the other hand, calibration experiment has been carried out before measuring, compensate for the return interference spectrum due to Fabry-perot optical fiber chamber to demodulation optical fiber
The influence to temperature survey caused by grating, so that measurement result is more accurate.
As shown in figure 1, the high speed based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating of the present invention is demodulated and filled
Put, including light source module 1, three-dB coupler, circulator 8, sensing unit 12 and demodulating unit 19.Single mode is used between each part
Optical fiber carries out optical signal transmission.
Light source module 1 includes three Distributed Feedback Lasers and a wide spectrum light source 5, and three Distributed Feedback Lasers are the first DFB laser
Device 2, the second Distributed Feedback Laser 3 and the 3rd Distributed Feedback Laser 4.The spectrum of three narrow-band light sources and the spectrum of the wide spectrum light source
Non-overlapping copies.Requirement according to demodulation to light source, narrow-band light source is DFB (Distributed Feed Back) laser, described
Wide spectrum light source uses amplified spontaneous emission source (ASE) or the super-fluorescence light source (SFS) based on doped fiber.
Sensing unit 12 includes optical fiber grating sensing structure 10 and Fabry-perot optical fiber chamber sensing arrangement 11.Sensing unit 12 is light
The compound sensor of the fiber grating composition of fine Fa-Po cavity and Non-stress packaging, or Fabry-perot optical fiber pressure/strain transducer
With the cascaded structure of fiber-optical grating temperature sensor.
Demodulating unit 19 includes the Coarse Wave Division Multiplexer (CWDM) 14 of 1 × 3 dense wave division multiplexer (DWDM) 13,1 × 2, light
Electric explorer 15, signal conditioning circuit 16, data collecting card 17 and computer 18.
The three beams laser of narrowband sent in light source module 1 is with a branch of wide spectrum optical while being coupled in four single-mode fibers 6, four
After Shu Guang is by 4 × 1 three-dB coupler 7, incide in circulator 8, then incoming sensing unit 12.Optical signal first enters to inject
Enter optical fiber grating sensing structure 10, the light wave for meeting fiber grating reflection kernel wavelength is reflected, and other light-wave transmissions enter light
Simultaneously multiple-beam interference occurs wherein for fine Fa-Po cavity sensing arrangement 11, and interference light returns to optical fiber grating sensing structure 10 and straight by its
Transmission is connect, the interference light is superimposed spectrum with the reflected light formation of fiber grating, and superposition spectrum is as shown in Figure 2.Wherein, Fabry-perot optical fiber
Chamber sensing arrangement 11 is used for pressure/strain measurement, and optical fiber grating sensing structure 10 is used for temperature survey.
Superposition spectrum as shown in Figure 2, by 1 × 2 three-dB coupler 9 respectively it is incident enter 1 × 3DWDM13 and 1 ×
2CWDM14, so that optical signal is divided into five tunnels.1 × the 3DWDM13 matches with three narrow-band light sources, the three-beam passed through
Chamber for demodulating Fabry-perot optical fiber chamber is long；Light through the 1 × 2CWDM14 is used for the demodulation of fiber grating reflection kernel wavelength.
Via photodetector 15, five road optical signals are converted to electric signal and enter signal condition unit 16.Electric signal is adjusted by signal
Reason unit 16, which is changed into data signal and is transferred to computer 18 by data collecting card 17, to be stored.By signal handler,
Stored data signal is analyzed, using the digital phase demodulating method of three wavelength with edge filter method respectively to Fabry-perot optical fiber
The change of cavity length amount of chamber and the drift value of fiber grating reflection kernel wavelength carry out fast demodulation, thus realize double parameters (temperature,
Pressure/strain) combined measurement.
Because three beams laser of narrowband and wide spectrum optical are separate so that the three beams for demodulating Fabry-perot optical fiber chamber long message swashs
Light will not be influenceed by wide spectrum optical.But when being demodulated using the wide spectrum optical returned from fiber grating to fiber grating, due to
Return to wide spectrum optical is influenceed by the interference spectrum of Fabry-perot optical fiber chamber so that mistake is produced during demodulating fiber bragg grating reflection kernel wavelength
Poor drift value by demarcation, it is necessary to be compensated.On the other hand, because the change of cavity length amount of Fabry-perot optical fiber chamber is due to that temperature becomes
Change the double influence with pressure/strain variation, therefore be also required to compensate.
Based on above-mentioned high-speed demodulating apparatus, what the present invention was provided is combined based on the double parameters of Fabry-perot optical fiber chamber and fiber grating
The high speed demodulation method of measurement, implements step as follows：
Step one：Carry out calibration experiment.
1. calibration experiment one：Obtain the demodulating error drift value Δ λ of fiber grating reflection kernel wavelength1Become with environment temperature
Relation between change amount Δ T, pressure/strain variation amount Δ X, it is as follows：
Δλ1=K1ΔT+K2ΔX (1)
K1Acquisition pattern：Standardization experimental apparatus as shown in Figure 3 is used in the embodiment of the present invention, temperature loading device is utilized
22 pairs of sensing units, 12 loading temperature, given temperature variation delta T.The superimposed light that sensing unit 12 is returned before and after temperature change
Spectrum also makes Fiber Optic Sensor as shown in figure 4, temperature variation Δ T not only makes fiber grating reflection kernel wavelength generate drift value Δ λ
Amber chamber length there occurs Δ LTChange, detection superimposed light by the light intensity change information obtained after 1 × 2CWDM, filtered using edge
The demodulation of ripple method obtains the drift value of the fiber grating reflection kernel wavelength comprising error demodulation amount.Optical fiber is obtained using spectrometer 25
The actual drift value of optical grating reflection centre wavelength.By the difference between actual drift value and demodulation drift value, it can obtain due to temperature
Degree change causes the error of fiber grating reflection kernel wavelength to demodulate drift value, so as to demarcate acquisition K1。
As shown in figure 3, the sensing unit 12 in high-speed demodulating apparatus of the present invention is inserted in temperature loading device 22, at this
The output end of circulator 8 in invention high-speed demodulating apparatus sets the joints of optical fibre 23 and ring flange 24, can be connected by optical fiber
Connect device 23 and the connection spectrometer 25 of ring flange 24.Temperature loading device 22 enters trip temperature loading to sensing unit 12, through excess temperature
Optical signal in sensing unit 12 after modulation, is detected by demodulating unit 19, and linear filtering method solution is finally utilized in a computer
Adjust the drift value Δ λ for obtaining fiber grating reflection kernel wavelength.Δ λ contains the demodulating error of fiber grating reflection kernel wavelength
Drift value Δ λ1With practical center wavelength shift Δ λ of the fiber grating caused by temperature change2.Utilize the joints of optical fibre
23rd, ring flange 24 is connected with spectrometer 25, optical signal in the sensing unit 12 after temperature modulation, is detected by spectrometer 25,
Obtain the actual drift value Δ λ of fiber grating reflection kernel wavelength2.So as to obtain the solution of fiber grating reflection kernel wavelength
Adjust error drift amount Δ λ1.By demodulating the difference between drift value and actual drift value, it can obtain because temperature change causes
The demodulating error drift value of fiber grating reflection kernel wavelength, so as to demarcate acquisition K1。
K2Acquisition pattern：Standardization experimental apparatus schematic diagram as shown in Figure 5, in the case of environment temperature is immovable, profit
With pressure/strain loading device 26 to 12 on-load pressures of sensing unit/strain, pressure/strain causes Fabry-perot optical fiber chamber length to produce
Comparison diagram is as shown in fig. 6, detail view such as Fig. 7 institutes of its corresponding fiber grating part before and after Δ L variable quantity, superposition spectrum
Show.After the superposition spectrum is by 1 × 3CWDM, the variable quantity of light intensity will be detected, can be demodulated by linear filtering method and obtain light
The error drift amount of fine optical grating reflection centre wavelength, so as to demarcate acquisition K2。
As shown in figure 5, the sensing unit 12 in high-speed demodulating apparatus of the present invention is inserted into pressure/strain loading device 26
In, the optical signal that stress/strain loading device 26 is carried out to sensing unit 12 in stress/strain loading, sensing unit 12 passes through
Unit 19 is demodulated after stress/strain modulation to detect, and is obtained using linear filtering method demodulation due to optical fiber caused by stress/strain
The error demodulation drift value of optical grating reflection centre wavelength, so as to demarcate acquisition K2。
2. calibration experiment two：The change of cavity length amount Δ L and variation of ambient temperature amount Δ T of Fabry-perot optical fiber chamber, pressure/strain become
Relation between change amount Δ X：
Δ L=K3ΔT+K4ΔX (2)
K3、K4Acquisition pattern：Caliberating device as shown in Figure 8, it is single using temperature, 27 pairs of sensings of pressure/strain loading device
Member 12 loads temperature and pressure/strain, long using the demarcation Fabry-perot optical fiber chamber chamber of SM125 (FBG) demodulators 28, so as to demarcate K3、K4Value.
As shown in figure 8, the sensing unit 12 of the present invention is placed individually into temperature, pressure/strain loading device 27, sense
The output end of unit 12 is connected with SM125 (FBG) demodulators 28, and SM125 (FBG) demodulators 28 are connected into computer 18.In SM125 (FBG) demodulators 28
Put the light that light source sends and enter sensing unit 12, temperature is loaded to sensing unit 12 using temperature, pressure/strain loading device 27
With pressure/strain, SM125 (FBG) demodulators 28 are returned to by the optical signal after temperature and stress/strain modulation, opened on computer
SM125 demodulation process, operation demodulation process obtains the demarcation chamber long value of Fabry-perot optical fiber chamber.Utilize SM125 (FBG) demodulators 28, demarcation
Fabry-perot optical fiber chamber chamber is long, so as to demarcate K3、K4。
Calibration experiment in step one, is completed before two parameter measurement is carried out, and formula (1) is used for being returned by Fabry-perot optical fiber chamber
Interference spectrum cause demodulating fiber bragg grating to compensate the influence that temperature survey is caused.
Step 2：Demodulate the drift value of the change of cavity length amount of Fabry-perot optical fiber chamber and the reflection kernel wavelength of fiber grating.
Using schematic device as shown in Figure 1, sensing unit 12 perceives ambient temperature, pressure/strain, utilizes three wavelength
Digit phase demodulating algorithm demodulates the change of cavity length amount Δ L of Fabry-perot optical fiber chamber, is reflected using edge filter method demodulating fiber bragg grating
The variation delta λ of centre wavelength.Wherein, Δ λ contains the demodulating error drift value Δ λ of fiber grating reflection kernel wavelength1With
The actual drift value Δ λ of reflection kernel wavelength of the fiber grating caused by the change of temperature2, fiber grating reflection kernel ripple
Long actual drift value Δ λ2It is represented by：
Δλ2=Δ λ-Δ λ1 (3)
Step 3：Solve temperature variation Δ T and pressure/strain variation amount Δ X.
Temperature variation Δ T and fiber grating reflection kernel wavelength actual drift value Δ λ2Between relation be：
Δλ2=A Δs T (4)
Wherein A is the temperature sensitive coefficient of constant, referred to as fiber grating, for bare optical fibers and bare optical gratings sensing arrangement, and its value is A
=λB(α+ξ), α is the thermal coefficient of expansion of optical fiber used in fiber grating；ξ is the thermo-optical coeffecient of optical fiber used in fiber grating；λBFor light
Reflection kernel wavelength during fine grating free state.It should be noted that one is due to the difference of doping component and doping concentration,
The thermal coefficient of expansion and thermo-optical coeffecient of various optical fiber have bigger difference, so as to cause the difference of A values；Two be due to fiber grating
The difference with annealing process condition is made, the difference of A values is also resulted in.Therefore in actual applications, it is necessary to by demarcating ability
For actual temperature measurement.Experimental provision schematic diagram as shown in Figure 9, the light that wide spectrum light source 5 is sent by 1 × 2 three-dB coupler
9 incoming sensing units 12, sensing unit 12 is inserted in temperature loading device 22, and temperature loading device 22 is carried out to sensing unit 12
Temperature is loaded, and the optical signal in sensing unit 12 after temperature modulation is returned by spectrum by 1 × 2 three-dB coupler 9
Instrument 25 is detected.The reflection kernel wavelength of optical fiber grating sensing structure under relevant temperature is detected using spectrometer 25, is obtained so as to demarcate
Obtain A values.
Using formula (1), (2), (3), (4), obtain temperature variation Δ T and be represented by：
The variation delta X of pressure/strain is：
Temperature and the variable quantity of pressure/strain in environment are finally obtained using formula (5), (6).
Claims (5)
1. a kind of high-speed demodulating apparatus based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating, it is characterised in that should
Device includes：Light source module, three-dB coupler, circulator, sensing unit and demodulating unit；Single-mode fiber is used between each part
Carry out optical signal transmission；
The light source module includes three narrow-band light sources and a wide spectrum light source, the spectrum of three narrow-band light sources and wide spectrum light source
Spectrum non-overlapping copies；The sensing unit includes Fabry-perot optical fiber chamber sensing arrangement and optical fiber grating sensing structure；The demodulation is single
Member includes 1 × 3 dense wave division multiplexer, 1 × 2 Coarse Wave Division Multiplexer, photodetector, signal conditioning circuit, data collecting card
With computer；
The three beams laser of narrowband that is sent in light source module and a branch of wide spectrum optical by four single-mode fiber simultaneous transmissions to 4 × 1 3dB
After coupler, four bundles light is coupled to be incided in circulator, then incoming sensing unit；
The optical signal of incoming sensing unit is first incident to enter optical fiber grating sensing structure, meets fiber grating reflection kernel wavelength
Light wave is reflected, and other light-wave transmissions enter Fabry-perot optical fiber chamber sensing arrangement and multiple-beam interference occurs wherein, and interference light is returned
Back into optical fibers grating sensing structure is simultaneously directly transmitted by it, and interference light is superimposed spectrum with the reflected light formation of fiber grating；
It is superimposed spectrum incident into 1 × 3 dense wave division multiplexer and 1 × 2 CWDM respectively by 1 × 2 three-dB coupler
Device, is divided into five tunnels by optical signal；1 × 3 dense wave division multiplexer matches with three narrow-band light sources, by 1 × 3 dense wave division multipurpose
The chamber that the three-beam of device output is used to demodulate Fabry-perot optical fiber chamber is long；The two-beam of 1 × 2 Coarse Wave Division Multiplexer output is used for optical fiber light
The demodulation of grid reflection kernel wavelength；Five road optical signals are converted to electric signal through photodetector and enter signal condition unit, electricity
Signal, which is changed into data signal by signal condition unit and is transferred to computer by data collecting card, to be stored, by telecommunications
Number it is demodulated, obtains the change of cavity length amount of Fabry-perot optical fiber chamber and the drift value of fiber grating reflection kernel wavelength.
2. a kind of high speed based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating according to claim 1 is demodulated
Device, it is characterised in that the sensing unit is the composite sensing of the fiber grating composition of Fabry-perot optical fiber chamber and Non-stress packaging
Device, or be Fabry-perot optical fiber pressure/strain transducer and the cascaded structure of fiber-optical grating temperature sensor.
3. a kind of high speed based on Fabry-perot optical fiber chamber and the double parameter combined measurements of fiber grating according to claim 1 is demodulated
Device, it is characterised in that described narrow-band light source is distributed feedback laser, described wide spectrum light source uses Amplified Spontaneous spoke
Penetrate light source or the super-fluorescence light source based on doped fiber.
4. the high speed demodulation method based on the high-speed demodulating apparatus described in claim 1, it is characterised in that the high speed demodulation method
Realize that step is as follows：
Step one：Carry out calibration experiment；
Obtain error drift amount Δ λ caused by demodulating fiber bragg grating reflection kernel wavelength1With variation of ambient temperature amount Δ T, pressure/
Relation between strain variation amount Δ X, it is as follows：
Δλ1=K1ΔT+K2ΔX (1)
Between the change of cavity length amount Δ L and variation of ambient temperature amount Δ T, pressure/strain variation amount Δ X that obtain Fabry-perot optical fiber chamber
Relation：
Δ L=K3ΔT+K4ΔX (2)
K1、K2、K3And K4For four coefficients, obtained by rating test；
Step 2：Demodulate the drift value of the change of cavity length amount of Fabry-perot optical fiber chamber and the reflection kernel wavelength of fiber grating；
Enter traveling optical signal measurement using high-speed demodulating apparatus, demodulated in a computer using the digital phase demodulating method of three wavelength
To the change of cavity length amount Δ L of Fabry-perot optical fiber chamber, the drift for obtaining fiber grating reflection kernel wavelength is demodulated using edge filter method
Measure Δ λ；The actual drift value Δ λ of fiber grating reflection kernel wavelength2It is expressed as：
Δλ2=Δ λ-Δ λ1 (3)
Step 3：Solve temperature variation Δ T and pressure/strain variation amount Δ X；
Temperature variation Δ T is obtained according to formula (4)：
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<mn>4</mn>
<mo>)</mo>
</mrow>
</mrow>
The variation delta X of pressure/strain is obtained according to formula (5)：
<mrow>
<mi>&Delta;</mi>
<mi>X</mi>
<mo>=</mo>
<mfrac>
<mrow>
<mo>-</mo>
<msub>
<mi>K</mi>
<mn>3</mn>
</msub>
<mi>&Delta;</mi>
<mi>&lambda;</mi>
<mo>+</mo>
<mrow>
<mo>(</mo>
<mi>A</mi>
<mo>+</mo>
<msub>
<mi>K</mi>
<mn>1</mn>
</msub>
<mo>)</mo>
</mrow>
<mi>&Delta;</mi>
<mi>L</mi>
</mrow>
<mrow>
<msub>
<mi>K</mi>
<mn>4</mn>
</msub>
<mi>A</mi>
<mo>+</mo>
<msub>
<mi>K</mi>
<mn>1</mn>
</msub>
<msub>
<mi>K</mi>
<mn>4</mn>
</msub>
<mo>-</mo>
<msub>
<mi>K</mi>
<mn>2</mn>
</msub>
<msub>
<mi>K</mi>
<mn>3</mn>
</msub>
</mrow>
</mfrac>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>5</mn>
<mo>)</mo>
</mrow>
</mrow>
Wherein, A is the temperature sensitive coefficient of fiber grating；
Temperature and the variable quantity of pressure/strain in environment are finally obtained using formula (4), (5).
5. high speed demodulation method according to claim 4, it is characterised in that in described step one, passes through following demarcation
Test to determine K1, it is specifically：
Sensing unit in described high-speed demodulating apparatus is inserted in temperature loading device, temperature loading device is to sensing unit
Enter the optical signal after temperature modulation in trip temperature loading, sensing unit, be demodulated unit detection, line is utilized in a computer
Property filter method demodulation obtain fiber grating reflection kernel wavelength drift value Δ λ；Δ λ includes fiber grating reflection kernel wavelength
Demodulating error drift value Δ λ1With practical center wavelength shift of the fiber grating caused by temperature change；
Light letter in the output end connection spectrometer of the circulator of high-speed demodulating apparatus, sensing unit after temperature modulation
Number, by spectrometer detection, obtain the actual drift value of fiber grating reflection kernel wavelength；Drifted about by demodulating drift value with actual
Difference between amount, is obtained because temperature change causes the error of fiber grating reflection kernel wavelength to demodulate drift value Δ λ1, from
And demarcate and obtain K1。
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| CN109520429B (en) * | 2018-11-26 | 2020-11-06 | 重庆大学 | Few-spectrum sampling point high-speed measurement system and method of white light interference type optical fiber Fabry-Perot sensor |
| CN110967057B (en) * | 2019-12-20 | 2021-08-17 | 中国地质大学（武汉） | Device and method for calibrating optical fiber strain and temperature coefficient |
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| CN113607196A (en) * | 2021-07-13 | 2021-11-05 | 中国航空工业集团公司北京长城计量测试技术研究所 | Fiber grating and Fabry-Perot cavity composite sensing signal decoupling method |
| CN113804247B (en) * | 2021-08-03 | 2024-05-14 | 西安理工大学 | Transformer oil temperature oil pressure multi-parameter monitoring system based on Fabry-Perot cavity and fiber bragg grating |
| CN113670359B (en) * | 2021-08-26 | 2022-08-12 | 中国核动力研究设计院 | High-speed demodulation system and method for optical fiber Fabry-Perot sensor |
| CN114235035A (en) * | 2021-11-29 | 2022-03-25 | 浙江大学 | Torque and temperature multi-parameter sensing device based on fiber bragg grating |
| CN117109465B (en) * | 2023-08-31 | 2024-04-12 | 交通运输部天津水运工程科学研究所 | Decoupling calibration method for multi-physical-field strain sensing signals |
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