CN201477200U - All-fiber type magnetic-field strength on-line sensing survey meter - Google Patents
All-fiber type magnetic-field strength on-line sensing survey meter Download PDFInfo
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- CN201477200U CN201477200U CN2009202092271U CN200920209227U CN201477200U CN 201477200 U CN201477200 U CN 201477200U CN 2009202092271 U CN2009202092271 U CN 2009202092271U CN 200920209227 U CN200920209227 U CN 200920209227U CN 201477200 U CN201477200 U CN 201477200U
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Abstract
The utility model relates to an all-fiber type magnetic-field strength on-line sensing survey meter. The output light of a broadband light source enters a long period fiber grating which is cured into a magnetostrictive material. The transmitted light of the long period fiber grating enters two fiber Bragg gratings by a fiber coupler. The long period fiber grating is taken as a sensing element; and a grating area of the long period fiber grating is put into a magnetic field to be tested. The first fiber Bragg grating is taken as a signal demodulating element, the reflected light of the first fiber Bragg grating is received by a photodiode, and the transmitted light thereof enters index-matching fluid. The second fiber Bragg grating is taken as a signal reference element, the reflected light of the second fiber Bragg grating is blocked by a fiber isolator, and the transmitted light enters the second photodiode. Output signals of the two photodiodes enter a signal amplifier and a data collecting card, and are processed and displayed by a computer in real time. The all-fiber type magnetic-field strength on-line sensing survey meter has the characteristics of high precision and cost performance and real-time test.
Description
Technical field
The utility model belongs to technical field of optical fiber sensing, particularly relates to the online sensing measurement instrument of a kind of full fiber type magnetic field intensity.
Background technology
Fiber grating is as a kind of optical device, is to set up a kind of space refractive index cycle to distribute in optical fiber, the device that the propagation characteristic of light is therein changed.According to the correlation theory of Elasticity, elastic deformation will take place in optical fiber under the effect that adds axial force, and elasto-optical effect can cause the change of material light refractive index, make that the spectral property of grating changes in the optical fiber.Fiber Bragg Grating and long period fiber grating are two kinds of fiber gratings common and the most the most frequently used, and both have outstanding using value at sensory field.When utilizing long period fiber grating, be coated with one deck magnetisable material or long period fiber grating is solidified into magnetostriction materials, perhaps paste thin magnetic film on the fiber grating surface at the skin of long period fiber grating as the sensing element of magnetic field intensity.The magnetic of external environment condition makes magnetisable material generation magnetostriction, causes the long period fiber grating axial strain, and elasto-optical effect makes variations in refractive index in the optical fiber, influences the spectral property of fiber grating, shows on its transmission spectrum and is moved by the resonance loss peak.The peak wavelength drift value at resonance loss peak and the pass of magnetic field intensity are:
In the formula, Δ λ
TBe the drift value of resonance loss peak wavelength in the transmission spectrum, k is the magnetostriction coefficient of long period fiber grating curing materials, n
CoBe the fiber core refractive index, μ is the fiber optic materials Poisson ratio, P
11And P
12Be fiber optic materials elasto-optical coefficient tensor, λ
TBe initial resonance loss peak wavelength, H is a magnetic field intensity to be measured.
Along with external magnetic field strength increases gradually, resonance loss peak wavelength variable quantity absolute value increases, but value is negative value (k is a negative value), promptly moves to short wavelength's direction.According to the variation relation of long period fiber grating peak wavelength, as long as the online peak wavelength that demodulates long period fiber grating can be learnt tested magnetic field intensity with tested magnetic field intensity.
In fiber grating sensing technology,, how simply, fast, accurately small wavelength amount of movement demodulation is come out, be the vital problem of optical fiber grating sensing because measured signal is Wavelength-encoding.For head it off, the researchist has developed some Wavelength demodulation technology in succession, mainly contains demodulation techniques, tunable optical source demodulation techniques, tunable filtering demodulation techniques, the matched filtering demodulation technology etc. of interfering.In above-mentioned demodulation method, the measurement range of interference demodulation techniques is subject to the Free Spectral Range of interferometer; Tunable optical source demodulation techniques input is convenient, the resolution height, but light source is difficult to make, and cost is higher; The scan period of tunable filtering demodulation techniques is long, and test speed is slow, and poor repeatability; The demodulation scope of matched filtering demodulation technology is too little.Because the existence of above-mentioned shortcoming makes the Wavelength demodulation technology become one of major obstacle of fiber grating sensing technology application.
Here propose to utilize the restitution element of Bragg fiber grating as the resonance loss peak wavelength of long period fiber grating.In the transmission spectrum of long-period gratings, (the linear fit error is 10 for linearity for its light intensity in a certain wavelength coverage that the strength degradation limit (or rising edge) of particular resonance loss peak is comprised
-4Reducing magnitude) (or increase) utilizes this point can realize the modulation of long-period gratings to wideband light source, the modulation back produce one in certain wavelength coverage intensity be the light source of linear change (descend or rise).Selection has the Bragg fiber grating of suitable wavelength, makes its central wavelength lambda
BBe in the linear zone scope at long-period gratings transmission spectrum maximum loss peak, and the centre position of close linear zone, as shown in Figure 2.When the wavelength of long period fiber grating is modulated by transducing signal, the reflection peak of Bragg fiber grating changes at the relative position of transmission spectrum linear zone, but its spectral pattern does not change with measured signal, then the absolute light power of Bragg fiber grating reflection is with linear change, therefore the photocurrent of photodetector is linear change, but the wavelength variations of demodulating long period optical fiber optical grating like this.This principle is similar to linear filter, but Bragg fiber grating has 2 obvious advantages with respect to linear filter, and promptly speed is fast and cost is little.
Summary of the invention
Technical problem to be solved in the utility model provide a kind of can be in real time, the full fiber type sensor of kinetic measurement magnetic field intensity, particularly can real-time, onlinely demodulate the signal demodulation techniques that the magnetic field intensity sensing element is the loss peak wavelength shift of long period fiber grating.
The technical scheme that its technical matters that solves the utility model adopts is: provide a kind of full fiber type magnetic field intensity online sensing measurement instrument, comprise wideband light source, long period fiber grating, 2 * 2 fiber coupler, first Bragg fiber grating, second Bragg fiber grating, a fibre optic isolater, first photodiode, second photodiode, index-matching fluid, signal amplifier, data collecting card, computing machine, the output light of described wideband light source enters long period fiber grating, the transmitted light of long period fiber grating enters first Fiber Bragg Grating through 2 * 2 fiber coupler part light, and another part light enters in second Fiber Bragg Grating through fibre optic isolater, and the transmitted light of first Fiber Bragg Grating enters in the index-matching fluid, its reflected light enters in first photodiode through coupling mechanism, and the transmitted light of second Fiber Bragg Grating enters in second photodiode; In first photodiode and the second photodiode output signals entering signal amplifier, the output signal of signal amplifier enters data collecting card, and the output signal of data collecting card is handled by computing machine and shown in real time.
When described sensing measurement instrument was measured magnetic field intensity, long period fiber grating was placed into as sensing element and treats in the measuring magnetic field that first Fiber Bragg Grating is as restitution element; Second Fiber Bragg Grating made the signal reference element.
When described sensing measurement instrument was measured magnetic field intensity, long period fiber grating is placed into to be treated in the measuring magnetic field, and the resonance loss peak wavelength drift value of long period fiber grating transmission spectrum and the square root of magnetic field intensity to be measured are linear.According to the variation relation of wavelength shift, as long as the online wavelength shift that demodulates can be learnt tested magnetic field intensity with tested magnetic field intensity.
Described first Fiber Bragg Grating is the signal restitution element, can onlinely demodulate the wavelength shift of long period fiber grating according to its output signal.
Described first Fiber Bragg Grating is the Fiber Bragg Grating through the temperature compensation encapsulation, and its centre wavelength does not change with variation of ambient temperature, with the measuring error that reduces to cause because of variation of ambient temperature.
Described second fiber optic cloth loudspeaker grating is common Fiber Bragg Grating, and its optical signal transmissive is as the reference signal, with the measuring error that reduces to cause because of the source device output optical power fluctuation.
The sensing element of system and signal restitution element are fiber optic component, can realize real-time, the on-line dynamic measurement of magnetic field intensity.
Beneficial effect
(1) the online sensing measurement instrument of full fiber type magnetic field intensity of the utility model realization only needs three fiber gratings commonly used just can realize dynamic, real-time, the on-line measurement of magnetic field intensity, and do not need special wavelength measurement equipment, only need just can calculate the loss peak wavelength of sensing element-long period fiber grating according to the output valve of photodiode accurately, compare with initial loss peak wavelength again, just can draw the drift value of loss peak wavelength, thereby learn by the intensity of measuring magnetic field.
(2) the utility model utilizes the combination of long period fiber grating master loss peak monolateral realization linear filtering function and Bragg fiber grating, realize the online in real time demodulation of long period fiber grating resonance loss peak wavelength, advantages such as the demodulation speed with linear filtering demodulation is fast, no diadic problem.
(3) the utility model utilize a Fiber Bragg Grating flashlight as reference light, eliminated since light source fluctuation to the influence that Wavelength demodulation causes, improved measuring accuracy.
(4) the utility model all is made of optical fiber and fiber optic passive device, and is stable and reliable for performance.The technological level of all components and parts is all very ripe, easy to make feasible, is convenient to promote the industrialization process of fiber grating sensing technology, can be widely used in various fields.
Description of drawings
Fig. 1 is the utility model sensor-based system synoptic diagram;
Fig. 2 is long period fiber grating transmission spectrum and Fiber Bragg Grating reflectance spectrum synoptic diagram.
Embodiment
Below in conjunction with specific embodiment, further set forth the utility model.Should be understood that these embodiment only to be used to the utility model is described and be not used in the restriction scope of the present utility model.Should be understood that in addition those skilled in the art can make various changes or modifications the utility model after the content of having read the utility model instruction, these equivalent form of values fall within the application's appended claims institute restricted portion equally.
As shown in Figure 1, the utility model is realized can be dynamically, the sensing measurement instrument of real-time, on-line measurement magnetic field intensity, and it comprises: the output light of wideband light source 1 enters long period fiber grating 2.Long period fiber grating is cured in the magnetostriction materials nickel.The transmitted light of long period fiber grating 2 is through 2 * 2 fiber coupler 3, and a part of light enters first Fiber Bragg Grating 4, and another part light enters in second Fiber Bragg Grating 8 through fibre optic isolater 7.The transmitted light of first Fiber Bragg Grating 4 enters in the index-matching fluid 5, and its reflected light enters in first photodiode 6 through fiber coupler 3.The transmitted light of second Fiber Bragg Grating 8 enters in second photodiode 9; In the output signal entering signal amplifier 10 of first photodiode 6, second photodiode 9, the output signal of amplifier 10 enters data collecting card 11, and the output signal of data collecting card is handled by computing machine 12 and shown in real time.Sensing element long period fiber grating 2 is placed into to be treated in the measuring magnetic field 13.
The utility model is realized can be dynamically, the sensing measurement instrument of real-time, on-line measurement magnetic field intensity, when measuring magnetic field intensity, long period fiber grating 2 is placed into as sensing element and treats in the measuring magnetic field 13, and the position in total system device synoptic diagram as shown in fig. 1.First Fiber Bragg Grating 4 is the Fiber Bragg Grating through the temperature compensation encapsulation, and its centre wavelength is not drifted about with variation of temperature, and it is as the signal restitution element.Second Fiber Bragg Grating 8 is common Fiber Bragg Grating, as signal with reference to grating.
The utility model is realized can be dynamically, the sensing measurement instrument of real-time, on-line measurement magnetic field intensity, parameters such as the cloth loudspeaker lattice centre wavelength of described two Bragg fiber gratings, bandwidth, reflectivity should be mated, and that both cloth loudspeaker lattice centre wavelength should be with long period fiber grating master loss peak is Wavelength matched.
The utility model is realized can be dynamically, the signal demodulation principle of the sensing measurement instrument of real-time, on-line measurement magnetic field intensity: Fig. 2 is the synoptic diagram of long period fiber grating transmission spectrum and Bragg fiber grating reflectance spectrum, dotted line is the reflectance spectrum of Bragg fiber grating 4, and solid line is the maximum resonance loss peak in the LPG transmitted spectrum.(the linear fit error is 10 for linearity for its light intensity in the wavelength coverage that the strength degradation limit (or rising edge) of loss peak is comprised
-4Reducing magnitude) (or increase), utilize this point can realize the modulation of long-period gratings to wideband light source, produce one in particular range of wavelengths intensity be the light source (can change) of linear change (descend or rise) referring to the monolateral light intensity at the maximum loss peak among Fig. 2.The spectrum of light in the wavelength coverage of being utilized after the long-period gratings modulation is linear.
Make Fiber Bragg Grating 4 have suitable wavelengths, make its central wavelength lambda
BBe in the linear zone scope of loss peak of long period fiber grating, and near the linear zone centre position, as shown in Figure 2.When measuring magnetic field intensity, long period fiber grating 2 is placed into to be treated in the measuring magnetic field, and when magnetic field intensity changes and the loss peak wavelength of long period fiber grating 2 when modulated, its peak wavelength will drift about, be that the spectrum linear zone will translation, but its spectral shape does not change with measured signal; And the centre wavelength of Fiber Bragg Grating 4 is constant, the relative difference of itself and long period fiber grating 2 loss peak wavelength changes, be that the Bragg fiber grating reflection peak changes at the relative position of spectrum linear zone, then Fan She absolute light power is with linear change, therefore the photocurrent of photodetector is linear change, but the peak wavelength of demodulating long period optical fiber optical grating variation like this.This principle is similar to linear filter, but the optical fiber restitution element has 2 obvious advantages with respect to linear filter, and promptly speed is fast and cost is little.
Claims (2)
1. online sensing measurement instrument of full fiber type magnetic field intensity, comprise wideband light source (1), long period fiber grating (2), 2 * 2 fiber coupler (3), first Bragg fiber grating (4), second Bragg fiber grating (8), a fibre optic isolater (7), first photodiode (6), second photodiode (9), index-matching fluid (5), signal amplifier (10), data collecting card (11), computing machine (12), it is characterized in that: the output light of described wideband light source (1) enters long period fiber grating (2), the transmitted light of long period fiber grating (2) enters first Fiber Bragg Grating (4) through 2 * 2 a part of light of fiber coupler (3), and another part light enters in second Fiber Bragg Grating (8) through fibre optic isolater (7), the transmitted light of first Fiber Bragg Grating (4) enters in the index-matching fluid (5), its reflected light enters in first photodiode (6) through coupling mechanism (3), and the transmitted light of second Fiber Bragg Grating (8) enters in second photodiode (9); In the output signal entering signal amplifier (10) of first photodiode (6) and second photodiode (9), the output signal of signal amplifier (10) enters data collecting card (11), and the output signal of data collecting card is handled by computing machine (12) and shown in real time.
2. the online sensing measurement instrument of a kind of full fiber type magnetic field intensity according to claim 1, it is characterized in that: when described sensing measurement instrument is measured magnetic field intensity, long period fiber grating (2) is placed into as sensing element and treats that in the measuring magnetic field (13), first Fiber Bragg Grating (4) is as restitution element; Second Fiber Bragg Grating (8) is made the signal reference element.
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| CN2009202092271U CN201477200U (en) | 2009-09-04 | 2009-09-04 | All-fiber type magnetic-field strength on-line sensing survey meter |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103472411A (en) * | 2013-10-10 | 2013-12-25 | 中南林业科技大学 | Magnetic field sensor based on Hybrid long-period fiber grating |
| CN103760504A (en) * | 2014-01-16 | 2014-04-30 | 昆明理工大学 | Fiber Bragg optical grating spatial magnetic field intensity sensor based on giant magnetostriction materials and use method of fiber Bragg optical grating spatial magnetic field intensity sensor |
| CN104155619A (en) * | 2014-08-20 | 2014-11-19 | 天津大学 | Distributed optical frequency domain reflection magnetic field sensing device based on magnetostriction and demodulation method |
| CN105954689A (en) * | 2016-04-27 | 2016-09-21 | 浙江大学 | Novel weak magnetic field sensor and detection method based on Ampere force |
| CN106125017A (en) * | 2016-08-31 | 2016-11-16 | 成都市和平科技有限责任公司 | A kind of magnetic field intensity measurement apparatus based on fiber grating |
| CN106772818A (en) * | 2017-01-23 | 2017-05-31 | 中国科学院上海光学精密机械研究所 | Measure all -fiber device of heavy caliber magneto optic isolator isolation ratio |
| CN108226819A (en) * | 2016-12-13 | 2018-06-29 | 中国移动通信集团上海有限公司 | A kind of ground magnetic field monitoring system and method based on fiber grating |
| CN110749952A (en) * | 2019-10-31 | 2020-02-04 | 武汉理工大学 | Method for preparing fiber grating array optical cable for positioning and measuring speed of high-speed magnetic suspension train |
| CN111736001A (en) * | 2020-06-12 | 2020-10-02 | 河南大学 | Novel optical current sensor, system and method based on magnetofluid and grating |
| CN113671230A (en) * | 2021-09-10 | 2021-11-19 | 中国计量大学 | Electromagnetic conversion type optical fiber sensitization current sensing probe |
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2009
- 2009-09-04 CN CN2009202092271U patent/CN201477200U/en not_active Expired - Fee Related
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103472411A (en) * | 2013-10-10 | 2013-12-25 | 中南林业科技大学 | Magnetic field sensor based on Hybrid long-period fiber grating |
| CN103760504A (en) * | 2014-01-16 | 2014-04-30 | 昆明理工大学 | Fiber Bragg optical grating spatial magnetic field intensity sensor based on giant magnetostriction materials and use method of fiber Bragg optical grating spatial magnetic field intensity sensor |
| CN103760504B (en) * | 2014-01-16 | 2016-06-08 | 昆明理工大学 | A kind of optical fiber Bragg raster space magnetic field intensity sensor based on giant magnetostrictive material and using method thereof |
| CN104155619A (en) * | 2014-08-20 | 2014-11-19 | 天津大学 | Distributed optical frequency domain reflection magnetic field sensing device based on magnetostriction and demodulation method |
| CN105954689B (en) * | 2016-04-27 | 2019-01-29 | 浙江大学 | A kind of novel Weak magentic-field sensor and detection method based on Ampere force |
| CN105954689A (en) * | 2016-04-27 | 2016-09-21 | 浙江大学 | Novel weak magnetic field sensor and detection method based on Ampere force |
| CN106125017A (en) * | 2016-08-31 | 2016-11-16 | 成都市和平科技有限责任公司 | A kind of magnetic field intensity measurement apparatus based on fiber grating |
| CN106125017B (en) * | 2016-08-31 | 2018-11-06 | 成都市和平科技有限责任公司 | A kind of magnetic field intensity measuring device based on fiber grating |
| CN108226819A (en) * | 2016-12-13 | 2018-06-29 | 中国移动通信集团上海有限公司 | A kind of ground magnetic field monitoring system and method based on fiber grating |
| CN106772818A (en) * | 2017-01-23 | 2017-05-31 | 中国科学院上海光学精密机械研究所 | Measure all -fiber device of heavy caliber magneto optic isolator isolation ratio |
| CN106772818B (en) * | 2017-01-23 | 2019-05-17 | 中国科学院上海光学精密机械研究所 | Measure all -fiber device of heavy caliber magneto optic isolator isolation ratio |
| CN110749952A (en) * | 2019-10-31 | 2020-02-04 | 武汉理工大学 | Method for preparing fiber grating array optical cable for positioning and measuring speed of high-speed magnetic suspension train |
| CN111736001A (en) * | 2020-06-12 | 2020-10-02 | 河南大学 | Novel optical current sensor, system and method based on magnetofluid and grating |
| CN113671230A (en) * | 2021-09-10 | 2021-11-19 | 中国计量大学 | Electromagnetic conversion type optical fiber sensitization current sensing probe |
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