CN2611935Y - Temp tuning optical fiber raster sensing demodulator - Google Patents
Temp tuning optical fiber raster sensing demodulator Download PDFInfo
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- CN2611935Y CN2611935Y CN 03229855 CN03229855U CN2611935Y CN 2611935 Y CN2611935 Y CN 2611935Y CN 03229855 CN03229855 CN 03229855 CN 03229855 U CN03229855 U CN 03229855U CN 2611935 Y CN2611935 Y CN 2611935Y
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- fiber
- optical fiber
- grating
- thermal tuning
- fiber grating
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Abstract
A temperature tuning optical fiber and grating sensing demodulator is characterized in that an optical fiber and grating (1) is fixed on a minitype electric resistance heater (2), wherein the two ends of the minitype electric resistance heater (2) are formed by a pair of down-leads (3) connecting with a modulated power source (4). The utility model has the advantages of comparatively simple structure, low cost, stable and reliable utilization, and large measuring extension, which can be simultaneously applied in optical fiber and grating distributed stress or/and temperature sensing system.
Description
Technical field
The utility model relates to the detuner of fiber-optic grating sensor, and particularly a kind of thermal tuning fiber sensor demodulator is mainly used in the technical field of Fibre Optical Sensor, optical measurement, optical device wavelength tuning.
Background technology
Fiber grating is a kind of optical filter with narrowband reflection characteristic that is produced on the optical fiber.Because elastic deformation, the thermal expansion character of silica fibre, with and hot light, elasto-optical effect, it has the sensitivity characteristic to temperature and stress.This sensitivity characteristic is linear in certain scope, meets following relation:
Δλ
ε/λ＝ε(1-γ) (1)
Δλ
T/λ＝(α+e)ΔT (2)
Formula: ε is the strain of optical fiber, and γ is the elasto-optical coefficient of fiber optic materials, and α is the coefficient of thermal expansion of fiber optic materials, and Δ T is a temperature variation,
Be thermo-optical coeffecient.Measure wavelength change just need can determine perception according to above-mentioned relation temperature and stress by profit.Therefore, as sensor, measure and read the gordian technique that the Bragg wavelength becomes practical application accurately and fast with fiber grating, the Bragg wavelength readout device that matches, promptly meaning is called the Primary Component that Bragg wavelength tuning detuner becomes Application in Sensing.
Formerly in the technology, for the demodulating process of optic fiber grating wavelength coding, traditional means is to use instruments such as spectrometer, monochromator or wavemeter.In addition people have proposed the scheme of some novel wavelength information demodulation, as Mach-Zehnder interferometer mode, adjustable fabry-perot filter method, matched fiber grating wave filter method etc.Conclusion is got up, and the demodulation techniques of fiber grating reflected light wavelength can be divided into following several types:
1, certain light signal that has that detected sensing head reflects is directly inputted in spectrometer, monochromator or the wavemeter, directly measures the wavelength location of fiber Bragg grating reflected signal.As technology [1]: Liu Zhiguo etc. formerly, the research of high-sensitivity optical fiber grating sensing characteristics tester, photon journal, 1999,28 (2): 138-141.This demodulation mode is simple, measuring accuracy is high, but these instruments are expensive and not portable.Only be suitable for the laboratory and use, inconvenience is applied in the actual sensor-based system.
2, utilize tunable laser as testing light source, optical maser wavelength continuous sweep in certain scope of output, according to the position of light signal in the scan period, the variation of tested optical fiber optical grating reflection optical wavelength be can draw, measuring optical fiber grating and reference optical fiber grating reflection optical wavelength perhaps drawn.As technology [2] formerly: Soek Hyun Yun, et al., Interrogation for fiber grating sensor arrays withwavelength-swept fiber laser, Optics Letters, 1998,23 (11): 843-845; Technology [3]: Guan Baiou etc. formerly, a kind of high-resolution fiber grating sensing demodulation technology, optics journal, 2000,20 (11): 1509-1513.The advantage of this method is the energy of reflection light height, and as long as general light power meter is used as receiving element, signal is easy to detect, the resolution height, and multiplexed realization is simple.But the deficiency of this method be light source to design and produce difficulty big, the cost height.
3, utilize wideband light source as testing light source, utilize wave filter or tunable optic filter, come sensed light signal with light power meter as restitution element for sensor fibre optical grating reflection light signal.This method can be divided into reflection-type and transmission-type two classes again.The former principle is as follows: incide on the FBG of receiving end from the reflected light of sensing FBG, if consistent with the reflected light wavelength of receiving end FBG, then be reflected on the detector.Drive reception FBG by PZT and finely tune, obtain the peak wavelength of sensing FBG.The precision of this method is subjected to the restriction of light source stability and external interference, to the stability requirement height of end of probe FBG spectrum.Technology [4]: M.A.Davis formerly, et al., Matched-filter interrogation technique for fiber Bragggrating arrays, Electronics Letters, 1995,31 (10): 822-823 has proposed the measurement scheme of transmission-type.The difference of this scheme and reflection-type is: photodetector is not to be placed on the catoptrical position of receiving end FBG, but places the position of transmitted light, determines whether coupling by monitoring having or not of transmitted light, thereby has improved detection sensitivity.This method requirement receiving end FBG and sensing FBG wavelength are approaching, and the wavelength coverage of sensing and demodulation is smaller.
4, edge filter method, adopt promptly that a kind of to have live width bigger, transmitance is the wave filter of linear change, with the reflecting light appearance convolution of sensing FBG, the signal that obtains is proportional with the position of FBG peak wavelength, thereby can know the FBG wavelength location by inference from signal magnitude, and as technology [5]: A.D.Kersey formerly, A review ofrecent developments in fiber optic sensor technology, Optical Fiber Technology, 1996,2,291-317.This method requires the demodulator filter good linearity, requires each component parameter stability of system.Therefore service condition is relatively harsher.
Because the defective that said method exists, the demodulation techniques in the fiber grating sensing system become one of major obstacle that this sensing technology applies.
The utility model content:
The technical problems to be solved in the utility model is to overcome the defective of above-mentioned technology formerly, and a kind of thermal tuning fiber sensor demodulator that utilizes the thermal tuning characteristic of fiber grating itself and make is provided.
Ultimate principle of the present utility model is to utilize the thermal tuning characteristic of fiber grating, and the spectral characteristic of optical fiber grating sensing head is scanned, and realizes demodulation.
Technical solution of the present utility model is as follows:
A kind of thermal tuning fiber sensor demodulator is characterized in that it is that fiber grating is fixed on the miniature electric resistance heater, and the two ends of this miniature electric resistance heater are linked to each other with a modulation power source by pair of lead wires and constitute.
Described miniature electric resistance heater can be the miniature resistance of pellet resistance material, also can be the annular metal film resistance that directly is produced on the optical fiber surface.
The using method of described thermal tuning fiber sensor demodulator is characterized in that it is with a plurality of peak wavelength (λ
1, λ
2, λ
3λ
n) after the series connection of different thermal tuning fiber grating, by fiber coupler and light signal (λ to be measured
x) optical fiber links to each other, this fiber coupler connects a photelectric receiver again.
The using method of described thermal tuning fiber sensor demodulator is characterized in that light signal (λ to be measured
x) optical fiber by a multichannel star-type coupler along separate routes by fiber coupler and a plurality of peak wavelength (λ
1, λ
2, λ
3λ
n) different thermal tuning fiber grating links to each other, each fiber coupler connects a photelectric receiver.
The using method of described thermal tuning fiber sensor demodulator is characterized in that it can be used for the distributed stress of fiber grating or/and temperature-sensing system.
Advantage of the present utility model and characteristics are:
(1) the utility model adopts the read-out device of tunable fiber grating as the sense light wavelength signals.Compare with the method that adopts spectrometer, monochromator, wavemeter, much with low cost, easy to utilize.
(2) signal demodulating equipment of the present utility model all adopts optical fiber and fiber optic element device, is a kind of system of full optical fiber.Between each device and the element, can all use the optical fiber splicer welding, constitute an integral body.Therefore, use reliable and stablely, realize instrumentation easily.
(3) the utility model utilizes the responsive to temperature characteristic of fiber grating to scan, and can measure the fiber grating peak wavelength of strain sensing head and Temperature probe simultaneously.As long as at the spectrum non-overlapping copies of two kinds of sensor fibre gratings, and be connected in series another reference optical fiber grating, just strain and temperature can be measured respectively.
(4) the utility model demodulation method is a kind of spectral scan method, can read the peak of fiber grating, adopts the fixed filters method to compare with the method that adopts principle of interference with some, has the big advantage of measurement range.
(5) the utility model is a kind of method that wavelength is directly measured, rather than calculates indirectly that from light intensity data are with a high credibility.
One of advantage of fiber-optic grating sensor is to be used as the distributed measurement system, and strain and temperature information that can the remote recording multiple spot have widely and use.The utility model fiber grating tuning detuner is as the requisite Primary Component of sensing measurement system, and its use value is embodied fully, has good cost performance, and expection has good market outlook.
Description of drawings:
Fig. 1: temperature tuning type fiber sensor demodulator, multiband series arrangement;
Fig. 2: temperature tuning type fiber sensor demodulator, multiband layout in parallel;
Fig. 3: detuner is applied to the distributed fiber grating sensor-based system;
Embodiment:
See also shown in Figure 1 earlier.But the structure of the utility model thermal tuning fiber grating demodulation device is the fiber grating 1 of demodulation to be fixed on the miniature electric resistance heater 2, and the two ends of this miniature electric resistance heater 2 are linked to each other with a modulation power source 4 by pair of lead wires 3.When the pair of lead wires 3 of modulation power source 4 by electric resistance heater 2 applied electric current, the Joule heat that resistance upper reaches excess current the produces fiber grating 1 of heating caused the variation of grating wavelength, realizes thermal tuning.Tuning range depends on range of temperature; If temperature is pressed the some cycles circulation, grating wavelength will be shown below with same intermittent scanning:
This detuner can use in a plurality of cascades, to enlarge measurement range.Fig. 1 is a series arrangement, and fiber grating 1 series connection of being selected at regular intervals by four peak wavelengths constitutes.When wavelength is λ
xLight signal to be measured during by fiber coupler 5 input, the peak wavelength of a certain fiber grating 1 in the detuner is scanned same λ
xWhen consistent, will reflex to coupling mechanism 5, and be detected by photelectric receiver 6.Fig. 2 is a layout in parallel, and the light signal of input shunts on the fiber grating 1 of each different peak wavelengths through multichannel star-type coupler 7, can realize the performance of multiband demodulation simultaneously equally.
Miniature electric resistance heater 2 in the utility model detuner can be the miniature resistance of sheet thermo electric material, also can be the annular metal film resistance that directly is produced on the optical fiber surface.The former makes easily, and is easy to use.Latter's efficient height, tuned speed are fast.
Lift an application example below again, the utility model is described in further detail.
Detuner of the present utility model can be applicable to the distributed stress of fiber grating or (with) temperature-sensing system, its typical light path layout is as shown in Figure 3.Wherein 10 is that peak wavelength is λ
εFiber grating, it is fixed on strain (or stress) structural member to be measured, is the sensing head of strain (or stress).The 11st, peak wavelength is λ
TFiber grating, it is fixed on the temperature object to be measured, is Temperature probe.5 is fiber couplers, and splitting ratio is 1 to 1 usually.8 is a wideband light source, and its luminescent spectrum scope is in same wave band with the fiber grating that is adopted.9 is isolators, and its effect is the influence of light wideband light source 8 that prevents to return from the sensor fibre optical grating reflection.The 12nd, be λ by wavelength
1Arrive the wavelengt demodulator of n tunable fiber grating 1 composition of λ n.The 6th, photo-detector, receive from light source 8 send, through strain or (with) Temperature probe 10,11 reflections, again through the light signal of wavelengt demodulator 12 transmissions.The optical fiber interface of above-mentioned all elements adopts direct welding process to connect.Wherein 13 for long optical cable, so that constitute distributed sensor-based system.
The peak wavelength λ of optical fiber grating sensing head 10 and 11 reflectance spectrums
εAnd λ
TAlong with the strain of object under test and temperature and change, shown in (1) and (2).The intensity of the light signal that receives on photo-detector 6 is the convolution of light source, sensing head and three spectral functions of spectrum demodulator, is shown below:
I＝∫f
1(λ)f
2(λ
ε)f
3(λ
n[c])dλ＝I(λ
ε-λ
n) (3)
I＝∫f
1(λ)f
2(λ
T)f
3(λ
n[c])dλ＝I(λ
T-λ
n) (4)
F in the formula
3(λ
n[c]) be the spectrum of the thermal tuning fiber grating filter of the utility model detuner, the tuning controlled variable of c representative wherein, such as voltage, electric current, the perhaps phase place of voltage, electric current.According to formula (3) and (4), from light intensity I that measures and the spectrum f that measures demarcation in advance
3(λ
n[c]) with the data that parameter c changes,, can obtain λ through computing
εAnd λ
T, realize the demodulation of fiber grating spectrum.
Claims (5)
1, a kind of thermal tuning fiber sensor demodulator is characterized in that it is that fiber grating (1) is fixed on the miniature electric resistance heater (2), and the two ends of this miniature electric resistance heater (2) are by pair of lead wires (3) formation that links to each other with a modulation power source (4).
2, thermal tuning fiber sensor demodulator according to claim 1 is characterized in that described miniature electric resistance heater (2) can be the miniature resistance of pellet resistance material, also can be the annular metal film resistance that directly is produced on the optical fiber surface.
3, the using method of thermal tuning fiber sensor demodulator according to claim 1 is characterized in that it is with a plurality of peak wavelength (λ
1, λ
2, λ
3λ
n) after the series connection of different thermal tuning fiber grating (1), by fiber coupler (5) and light signal (λ to be measured
x) optical fiber links to each other, this fiber coupler (5) connects a photelectric receiver (6) again.
4, the using method of thermal tuning fiber sensor demodulator according to claim 1 is characterized in that light signal (λ to be measured
x) optical fiber by a multichannel star-type coupler (7) along separate routes by fiber coupler (5) and a plurality of peak wavelength (λ
1, λ
2, λ
3λ
n) different thermal tuning fiber grating (1) links to each other, each fiber coupler (5) connects a photelectric receiver (6).
5, the using method of thermal tuning fiber sensor demodulator according to claim 1 is characterized in that it can be used for the distributed stress of fiber grating or/and temperature-sensing system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03229855 CN2611935Y (en) | 2003-03-28 | 2003-03-28 | Temp tuning optical fiber raster sensing demodulator |
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|---|---|---|---|
| CN 03229855 CN2611935Y (en) | 2003-03-28 | 2003-03-28 | Temp tuning optical fiber raster sensing demodulator |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104052551A (en) * | 2013-03-15 | 2014-09-17 | 富士通株式会社 | Optical signal demodulator, optical signal demodulating method, and optical add-drop multiplexer |
| CN108563261A (en) * | 2018-03-14 | 2018-09-21 | 合肥光万信息科技有限公司 | A kind of double channel optical fiber intelligence temperature demodulation device |
| CN109506686A (en) * | 2018-12-19 | 2019-03-22 | 武汉理工光科股份有限公司 | A method of it improves entirely with optical fiber Grating examinations performance |
-
2003
- 2003-03-28 CN CN 03229855 patent/CN2611935Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104052551A (en) * | 2013-03-15 | 2014-09-17 | 富士通株式会社 | Optical signal demodulator, optical signal demodulating method, and optical add-drop multiplexer |
| CN108563261A (en) * | 2018-03-14 | 2018-09-21 | 合肥光万信息科技有限公司 | A kind of double channel optical fiber intelligence temperature demodulation device |
| CN109506686A (en) * | 2018-12-19 | 2019-03-22 | 武汉理工光科股份有限公司 | A method of it improves entirely with optical fiber Grating examinations performance |
| CN109506686B (en) * | 2018-12-19 | 2021-03-23 | 武汉理工光科股份有限公司 | Method for improving detection performance of isotactic fiber bragg grating |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20040414 |