CN105737753A - Light intensity modulation type signal demodulation system and signal demodulation method - Google Patents
Light intensity modulation type signal demodulation system and signal demodulation method Download PDFInfo
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- CN105737753A CN105737753A CN201610077376.1A CN201610077376A CN105737753A CN 105737753 A CN105737753 A CN 105737753A CN 201610077376 A CN201610077376 A CN 201610077376A CN 105737753 A CN105737753 A CN 105737753A
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- optical fiber
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- biconial
- light intensity
- intensity modulation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
Abstract
The invention discloses a light intensity modulation type signal demodulation system and signal demodulation method, and belongs to the technical field of light intensity modulation. A high-performance function signal generator is applied to provide an excitation source to light modulation signals, the light modulation signals enter a sensing optical fiber and a reference arm optical fiber through an optical fiber coupler, and reflected light carries strain and temperature information to reach a photoelectric detector through a coupler. The signals are accessed to an oscilloscope through amplification and filtering processing so as to observe phase difference. The system is simple in structural arrangement, high in sensitivity, high in precision and rapid in reaction. The method can be used for various occasions requiring obtaining of real-time strain monitoring data.
Description
Technical field
The invention belongs to light intensity modulation technical field, relate to a kind of light intensity modulation type signal demodulating system and signal demodulating method, be specifically related to light intensity modulation type signal demodulating system and the signal demodulating method of a kind of polymer optical fiber strain transducer with temperature-compensating.
Background technology
Along with the fields such as modern industry, space technology, military affairs are progressively to automatization and intelligent development, the requirement of the sensitivity of sensor, precision, reliability etc. is continuously increased, optical fiber sensor because it is highly sensitive, fast response time little, corrosion-resistant compared with strong anti-electromagnetic interference capability, good dynamic range, volume, networking, distributed, multiple spot, big region, the advantage such as synchronous detecting, enjoy the favor of domestic and international expert and user.The device of plastic polymer optical fiber perceptually signal is compared with glass optical fiber has more advantage: the Young's modulus that (a) polymer light fiber sensor is pliable and tough, less, bigger thermo-optical coeffecient and bigger thermal coefficient of expansion can provide higher sensitivity and broader response range；B () plastic optical fiber transceiver module uses the HONGGUANG of 650nm wavelength as electrical/optical or optical electrical switching device, direct voltage output signal makes demodulating system cost be greatly reduced；C () has that better bend performance, core diameter are big, numerical aperture is big, high with the coupling efficiency of light source and receptor, and end face processing is simple, have easy connected mode and the advantage such as simple interface unit.
Fibre optic strain sensor conventional at present has: Brillouin scattering is distributed, grating type optical fiber, mode-interference type, light intensity modulation type etc., they have highly sensitive, anti-electromagnetic interference capability is strong, dynamic range is big, fast response time, can carry out the advantages such as networking, distributed, multiple spot, big region, synchronous detecting, is subject to the attention of lot of domestic and foreign researcher.But first three type optical fiber sensor needs the making apparatus of costliness, LASER Light Source, optical coupling device, electrooptical device etc. and processing technology relative complex.And existing polymer optical fiber strain transducer precision is not high and is not possessed temperature compensation function by temperature interference.
Summary of the invention
It is an object of the invention to provide a kind of light intensity modulation type signal demodulating system and signal demodulating method, this system structure arranges simply, highly sensitive, and precision is high, is swift in response；The method can be used in the various occasions needing to obtain real-time strain monitoring data.
The present invention is achieved through the following technical solutions:
A kind of light intensity modulation type signal demodulating system, including function signal generator, signal (FBG) demodulator, fiber coupler, data acquisition module and oscillograph；
Function signal generator, signal (FBG) demodulator and fiber coupler are sequentially connected, the driving source that function signal generator provides sends the light with modulation signal by signal (FBG) demodulator, then through fiber coupler, light is divided into two branch roads, first branch road is sequentially provided with the first fiber coupler, the first photodetector and for providing the sensor fibre of optical strain information, the second branch road is sequentially provided with the second fiber coupler, the second photodetector and for providing the reference arm optical fiber of temperature compensation information；First photodetector and the second photodetector are connected with data acquisition module respectively, and data acquisition module is connected with oscillograph.
Function signal generator is connected with data acquisition module and oscillograph respectively.
Described for providing the sensor fibre of optical strain information to include optical fiber kernel and the outer quilt of optical fiber, optical fiber kernel is made up of fibre core and surrounding layer；On any one section of this sensor fibre, the two ends of fibre core are cylindrical section, and middle part is biconial coupling section.
Described for providing the reference arm optical fiber of temperature compensation information to include optical fiber kernel and the outer quilt of optical fiber, optical fiber kernel is made up of fibre core and surrounding layer；On any one section of this reference arm optical fiber, the two ends of fibre core are cylindrical section, middle part couples section for biconial, and this biconial coupling section is made up of biconial structural area and the package floor being coated on outside biconial structural area, and middle thin two ends, biconial structural area are thick and are arranged symmetrically with；Match formation cylindrical-shaped structure with package floor in biconial structural area, and this cylindrical-shaped structure is identical with the cylindrical section radius at fibre core two ends；It is fixed in structural substrates by adhesive layer at this cylindrical-shaped structure.
The least radius boring district in the middle part of biconial structural area is r0, and the radius of fibre core is r1, and r0 is r1 0.2～0.9 times.
The length of biconial coupling section is 10～100mm.
It is also filled with adhesive layer in the space that biconial structural area coordinates with package floor.
The invention also discloses the method carrying out signal demodulation based on above-mentioned system, comprise the following steps:
1) function signal generator sends the driving source of light modulating signal, and output sinusoidal signal sin (2 π ft) is to drive LED light source output electroencephalogram；
2) being divided into two branch roads through the light path of fiber coupler, electroencephalogram respectively enters sensor fibre and reference arm optical fiber, and after reflection, sensor fibre carries the strain information the first photodetector on its branch road；Reference arm optical fiber then carries the temperature information the second photodetector on its branch road；The signal of telecommunication of the first photodetector output isThe signal of telecommunication of the second photodetector output is
3) again by step 2) signal of telecommunication that obtains accesses oscillograph through amplifying, after Filtering Processing, observes φ1、φ2With initial zero phase difference, it is thus achieved that light intensity modulation type signal demodulation response results.
Compared with prior art, the present invention has following useful technique effect:
Light intensity modulation type signal demodulating system disclosed by the invention, driving source is provided for light modulating signal with high performance function signal generator, enter sensor fibre and reference arm optical fiber through fiber coupler, the reflection light of entrance sensor fibre and reference arm optical fiber carries strain respectively and temperature information arrives photodetector through fiber coupler.Signal accesses oscillograph to observe phase differential after amplification, Filtering Processing.The system of the present invention introduces optical fiber reference arm technology, the compensation that sensor temperature is responded simultaneously can be reached, the shortcoming that strain and temperature are responded by general polymer fibre optic strain sensor simultaneously can be overcome, thus the signal demodulating system of the present invention can be effectively improved accuracy and sensitivity, it is swift in response.
Further, the present invention utilizes the stress of conical region to concentrate principle, biconial polymer optical fiber is applied to strain detecting, optical fiber after possibly tapered when same pulling force, owing to the stress of conical region concentrates the strain variation making this region relatively big, sensor output strain sensitivity just can improve accordingly.
Method based on said system disclosed by the invention, be swift in response, precision is high, highly sensitive, it is possible to for needing to obtain the various occasions of real-time strain monitoring data.
Accompanying drawing explanation
Fig. 1 is the light intensity modulation type signal demodulating system structural representation of the present invention；
Fig. 2 is sensor of the invention polymer optical fiber section schematic cross-section；
Fig. 3 is the structural representation of Inventive polymers fibre optic strain sensor；
Fig. 4 is Inventive polymers fibre optic strain sensor biconial regional structure schematic diagram.
Wherein, 1 is function signal generator；2 signal (FBG) demodulators；3 is fiber coupler；4-1 is the first photodetector；4-2 is the second photodetector；5 is data acquisition module；6 is oscillograph；7-1 is sensor fibre；7-2 is reference arm optical fiber；8 is fibre core；9 is the outer quilt of optical fiber；10 is surrounding layer；11 is package floor；12 is structural substrates；13 is adhesive layer.
Detailed description of the invention
Below in conjunction with specific embodiment, the present invention is described in further detail, and the explanation of the invention is not limited.
Referring to Fig. 1, light intensity modulation type signal demodulating system disclosed by the invention, including function signal generator 1, signal (FBG) demodulator 2, fiber coupler 3, data acquisition module 5 and oscillograph 6.
Function signal generator 1, signal (FBG) demodulator 2 are sequentially connected with fiber coupler 3, the driving source that function signal generator 1 provides sends the light with modulation signal by signal (FBG) demodulator 2, then through fiber coupler 3, light is divided into two branch roads, first branch road is provided with the first fiber coupler 3-1, the first photodetector 4-1 and for providing the sensor fibre 7-1 of optical strain information, and the second branch road is provided with the second fiber coupler 3-2, the second photodetector 4-2 and for providing the reference arm optical fiber 7-2 of temperature compensation information；First photodetector 4-1 and the second photodetector 4-2 is connected with data acquisition module 5 respectively, and data acquisition module 5 is connected with oscillograph 6.Function signal generator 1 is connected with data acquisition module 5 and oscillograph 6 respectively.
Required experiment equipment such as data acquisition module 5, oscillograph 6 etc. are high accuracy, high-sensitive electrical signal detection equipment experiment equipment, it is ensured that in signal processing, sensor is exported ultra-weak electronic signal undistorted.
Referring to Fig. 2, Fig. 3 and Fig. 4, described for providing the sensor fibre of optical strain information to include outside optical fiber kernel and optical fiber by 9, optical fiber kernel is made up of fibre core 8 and surrounding layer 10；On any one section of fibre optic strain sensor, the two ends of fibre core 8 are cylindrical section, and middle part is biconial coupling section.
Described for providing the reference arm optical fiber of temperature compensation information to include outside optical fiber kernel and optical fiber by 9, optical fiber kernel is made up of fibre core 8 and surrounding layer 10；On any one section of this reference arm optical fiber, the two ends of fibre core 8 are cylindrical section, middle part couples section for biconial, and this biconial coupling section is made up of biconial structural area and the package floor 11 being coated on outside biconial structural area, and middle thin two ends, biconial structural area are thick and are arranged symmetrically with；Match formation cylindrical-shaped structure with package floor 11 in biconial structural area, and this cylindrical-shaped structure is identical with the cylindrical section radius at fibre core 8 two ends；Structural substrates 12 it is additionally provided with bottom this cylindrical-shaped structure.
The central cone district least radius r of the biconial structural area in sensor fibre and reference arm optical fiber0For fiber core radius r10.2～0.9 times, the central cone district radius r of biconial structural area0More little, sensitivity is more high.The length that above-mentioned biconial structure is gone can between 10～100mm.
After biconial structural area is introduced into optical fiber, the pattern propagated can be made a significant impact in optical fiber, energy coupling and interference effect between different mode, can be occurred to realize the perception to multiple physical quantity.Its compact conformation, good mechanical stability, fast response time.The present invention utilizes the stress of conical region to concentrate principle, biconial polymer optical fiber is applied to strain detecting, optical fiber after possibly tapered when same pulling force, owing to the stress of conical region concentrates the strain variation making this region relatively big, sensor output strain sensitivity just can improve accordingly.
Based on system disclosed above, the present invention carries out the method for signal demodulation and is:
Driving source is provided with high performance function signal generator 1, the light with modulation signal is sent by signal (FBG) demodulator 2, through fiber coupler 3 light path is divided into two and respectively enters sensor fibre and reference arm optical fiber, optical signal is changed into the signal of telecommunication through photodetector by fiber coupler 3 and is stored in data acquisition module 5 by reflection light, and is shown on oscillograph 6.Function signal generator 1 excitation source signal can also be read out on oscillograph 6 and be stored in data acquisition module 5.
Function signal generator 1 provides driving source for light modulating signal, assume that its output sinusoidal signal sin (2 π ft) is to drive LED light source output electroencephalogram, light path through fiber coupler 3 is divided into two branch roads, electroencephalogram respectively enters sensor fibre and reference arm optical fiber, after reflection, sensor fibre carries the strain information the first photodetector 4-1 on its branch road；Reference arm optical fiber then carries the temperature information the second photodetector 4-2 on its branch road；The signal of telecommunication of the first photodetector 4-1 output isThe signal of telecommunication of the second photodetector 4-2 output isAgain the signal of telecommunication obtained is accessed oscillograph 6 after amplification, Filtering Processing, observeWith initial zero phase difference, it is thus achieved that light intensity modulation type signal demodulation response results.
In sum, problem strain and temperature responded simultaneously due to polymer optical fiber strain transducer in prior art relies on single Fibre Optical Sensor to be difficult to solve, the present invention starts with from optical fiber reference arm technology and light intensity modulation technology, first research optical fiber thermo-optical coeffecient and the thermal coefficient of expansion impact on reference arm optical fiber lightwave transmission characteristics, discloses its rule with ambient temperature change；Secondly, the parameter impact on sensor evanescent waves characteristic such as binding analysis optical fiber thermo-optical coeffecient, thermal coefficient of expansion, stress optical coefficient, specify the relation of itself and stress, variations in temperature；Finally, for rejecting temperature interference, regulation experiment parameter (waveform of modulation light and frequency, amplitude etc.) on this basis, and it is optimized (lambda1-wavelength, sensor and reference arm fiber lengths, Transmission Fibers length etc.) on affecting strain transducer with the parameters in Temperature cross-over sensitivity.The selection (as modulated waveform and frequency, amplitude, lambda1-wavelength, sensor and reference arm fiber lengths, the Transmission Fibers length etc. of light) of the relevant parameter in realizing for the sensor demodulating system circuit design of high stable and hardware provides strong reference.
The present invention is by optical fiber reference arm technology and light intensity modulation technology, it is applied in polymer optical fiber strain sensing temperature-compensating experimental program, adopt high-precision function signal generator as modulation optical signal driving source, it is ensured that multiple waveforms and frequency thereof, amplitude accurately trigger；Use high-precision data acquisition module, it is ensured that signal can be maximally maintained original waveform in collection, amplification, denoising etc. process；Use high-precision oscillograph, it is ensured that tiny signal can detect seizure.So the phase-detection of modulation light is had significantly high sensitivity by this experiment building plan, circuit design and the hardware of the sensor demodulating system of high stable are realized providing effective reference by the parameters optimization (waveform of modulation light and frequency, amplitude etc.) obtained of thus setting out.Sensor and reference arm optical fiber are being carried out on the basis of theoretical modeling and experiment, setting up comprehensively complete light intensity modulation type polymer optical fiber strain transducer Design of Temperature Compensation scheme, and to the method that relevant parameter in scheme is optimized design.
Claims (8)
1. a light intensity modulation type signal demodulating system, it is characterized in that, including function signal generator (1), signal (FBG) demodulator (2), fiber coupler (3), data acquisition module (5) and oscillograph (6)；
Function signal generator (1), signal (FBG) demodulator (2) and fiber coupler (3) are sequentially connected, the driving source that function signal generator (1) provides sends the light with modulation signal by signal (FBG) demodulator (2), it is divided into two branch roads then through fiber coupler (3), first branch road is sequentially provided with the first fiber coupler (3-1), first photodetector (4-1) and for providing the sensor fibre (7-1) of optical strain information, second branch road is sequentially provided with the second fiber coupler (3-2), second photodetector (4-2) and for providing the reference arm optical fiber (7-2) of temperature compensation information；First photodetector (4-1) is connected with data acquisition module (5) respectively with the second photodetector (4-2), and data acquisition module (5) is connected with oscillograph (6).
2. light intensity modulation type signal demodulating system according to claim 1, it is characterised in that function signal generator (1) is connected with data acquisition module (5) and oscillograph (6) respectively.
3. light intensity modulation type signal demodulating system according to claim 1, it is characterized in that, described for providing the sensor fibre of optical strain information to include optical fiber kernel and the outer quilt (9) of optical fiber, optical fiber kernel is made up of fibre core (8) and surrounding layer (10)；On any one section of this sensor fibre, the two ends of fibre core (8) are cylindrical section, and middle part is biconial coupling section.
4. light intensity modulation type signal demodulating system according to claim 1, it is characterized in that, described for providing the reference arm optical fiber of temperature compensation information to include optical fiber kernel and the outer quilt (9) of optical fiber, optical fiber kernel is made up of fibre core (8) and surrounding layer (10)；On any one section of this reference arm optical fiber, the two ends of fibre core (8) are cylindrical section, middle part couples section for biconial, this biconial coupling section is made up of biconial structural area and the package floor (11) being coated on outside biconial structural area, and in the middle of biconial structural area, thin two ends slightly and are arranged symmetrically with；Match formation cylindrical-shaped structure with package floor (11) in biconial structural area, and this cylindrical-shaped structure is identical with the cylindrical section radius at fibre core (8) two ends；It is fixed in structural substrates (12) by adhesive layer (13) at this cylindrical-shaped structure.
5. the light intensity modulation type signal demodulating system according to claim 3 or 4, it is characterised in that the least radius boring district in the middle part of biconial structural area is r0, and the radius of fibre core (8) is r1, and r0 is r1 0.2～0.9 times.
6. the light intensity modulation type signal demodulating system according to claim 3 or 4, it is characterised in that the length of biconial coupling section is 10～100mm.
7. light intensity modulation type signal demodulating system according to claim 4, it is characterised in that be also filled with adhesive layer (13) in the space that biconial structural area coordinates with package floor (11).
8. the method carrying out signal demodulation based on the system described in any one in claim 1～7, it is characterised in that comprise the following steps:
1) function signal generator (1) sends the driving source of light modulating signal, and output sinusoidal signal sin (2 π ft) is to drive LED light source output electroencephalogram；
2) it is divided into two branch roads through the light path of fiber coupler (3), electroencephalogram respectively enters sensor fibre (7-1) and reference arm optical fiber (7-2), after reflection, sensor fibre carries the strain information the first photodetector (4-1) on its branch road；Reference arm optical fiber then carries the temperature information the second photodetector (4-2) on its branch road；The signal of telecommunication that first photodetector (4-1) exports isThe signal of telecommunication that second photodetector (4-2) exports is
3) again by step 2) signal of telecommunication that obtains accesses oscillograph (6) through amplifying, after Filtering Processing, observesWith initial zero phase difference, it is thus achieved that light intensity modulation type signal demodulation response results.
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Cited By (2)
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| CN105738007A (en) * | 2016-02-03 | 2016-07-06 | 西安交通大学 | Biconical polymer optical fiber probe and preparation method thereof and temperature sensor |
| CN108036728A (en) * | 2017-12-14 | 2018-05-15 | 大连理工大学 | A kind of phase difference solution mode fiber optics displacement measuring method and instrument |
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| CN1699943A (en) * | 2005-05-27 | 2005-11-23 | 上海大学 | Hipyramid type optical fiber fade down wave temperature sensor and method for manufacturing its bipyramid optical fiber probe |
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