CN203908511U - Fiber bragg grating strain detection device - Google Patents
Fiber bragg grating strain detection device Download PDFInfo
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- CN203908511U CN203908511U CN201420329382.8U CN201420329382U CN203908511U CN 203908511 U CN203908511 U CN 203908511U CN 201420329382 U CN201420329382 U CN 201420329382U CN 203908511 U CN203908511 U CN 203908511U
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Abstract
The utility model discloses a fiber bragg grating strain detection device, which comprises a compound light source, a coupler, an optical circulator, an acousto-optic tunable filter, a conversion driving device, a reference grating, an optical switch and a fiber bragg grating strain sensor, wherein the compound light source is in coupling connection with the coupler; the coupler is connected with the reference grating through the optical circulator; the optical circulator is connected with the conversion driving device through the acousto-optic tunable filter; and the reference grating is connected with the fiber bragg grating strain sensor through the optical switch. The fiber bragg grating strain detection device is suitable for a fiber bragg grating sensing and demodulating system which is designed based on a demodulating technology within the full spectrum range of the AOTF (acousto-optic tunable filter), greatly improves the sensing and demodulating range of the system and solves the bottleneck problem of large-scale application of fiber bragg grating sening when compared with the existing fiber bragg grating sensing and demodulating system based on FFP (Tunable optical filter) technology.
Description
Technical field
The utility model relates to optical fiber grating sensing field, particularly a kind of fiber grating strain pick-up unit.
Background technology
Tunable fiber Fabry-Perot wave filter (FFP) has been widely used in the signal demodulation of sensing grating, wherein, this wave filter can be described by the band-pass response of Lorentz spectral line shape, and typical 3dB spectral line width is 0.3nm, and working range is tens nanometers.
Tunable fiber Fabry-Perot chamber is by Piezoelectric Ceramic, and it is long in order to change chamber to apply periodic sawtooth voltage signal, carries out periodic filter scan with the wavelength of realizing determining region.It can be inquired about successively to the wavelength information of each fiber Bragg (Bragg diffraction) grating sensing unit in measurement range, and front to surveyed wavelength information and skew wavelength information is compared, obtain the wavelength shift of each sensing element, utilize side-play amount and measured between variation relation, just can judge the size that corresponding sensing element institute sensing physical quantity changes, reach the object of demodulation.
But adopt the optical fiber grating regulating system of FFP tunable optic filter demodulation, demodulation speed is 5Hz at present, and working range is tens nanometers, can not meet the demand of the extensive strain sensing monitoring system day by day strengthening.
Utility model content
In order to solve the problem that optical fiber grating regulating system demodulation speed is slow, light source bandwidth is little existing in prior art, the utility model proposes a kind of fiber grating strain pick-up unit.
Fiber grating strain pick-up unit of the present utility model, comprise: composite light source, coupling mechanism, optical circulator, acousto-optic tunable filter, conversion driving device, benchmark grating, photoswitch, fiber Bragg grating strain sensor, composite light source and coupling mechanism are of coupled connections;
Coupling mechanism is connected with benchmark grating by optical circulator; Optical circulator is connected with conversion driving device by acousto-optic tunable filter; Benchmark grating is connected with fiber Bragg grating strain sensor by photoswitch.
In technique scheme, conversion driving device comprises: photoelectric conversion module, signal processing module, radio-frequency driven controller, and acousto-optic tunable filter is connected with signal processing module by photoelectric conversion module;
Radio-frequency driven controller is connected with acousto-optic tunable filter, signal processing module respectively.
In technique scheme, conversion driving device also comprises operational amplification circuit, and photoelectric conversion module is connected with signal processing module by operational amplification circuit.
In technique scheme, composite light source comprises the wideband light source of two different spectral ranges.
In technique scheme, coupling mechanism is waveguide type fiber coupler.
In technique scheme, the angle of release of coupling mechanism is in 30 °.
In technique scheme, optical circulator is three ports light rings.
In technique scheme, acousto-optic tunable filter comprises single axial birefringence crystal, piezoelectric transducer, high-frequency signal source, and piezoelectric transducer is bonded in a side of single axial birefringence crystal; High-frequency signal source carries out action of radio to piezoelectric transducer.
In technique scheme, photoelectric conversion module is PIN photodiode.
In technique scheme, benchmark grating is the fiber grating not encapsulating.
Fiber grating strain pick-up unit of the present utility model, optical fiber grating sensing, the demodulating system of the demodulation techniques design based on the full spectral range of AOTF (acousto-optic tunable filter), follow optical fiber grating sensing, the demodulating system based on FFP (turnable fiber filter) technology at present to compare, greatly improve sensing, the demodulation scope of system, solved the bottleneck problem of optical fiber grating sensing large-scale application.
AOTF (acousto-optic tunable filter) can select any one wavelength coverage to carry out continuous sweep, can choose scanning according to effective wave band of tested optical fiber grating sensing, shorten sweep time, solved the problem of optical fibre grating high-speed sensing and demodulating.AOTF is all solid state light-splitting device, without moving-member, anti-seismic performance is good, adopt hermetically sealed design, insensitive to environmental impact (as strain, humidity, dust etc.), instrument working stability, has solved the temperature drift problem of the fiber grating strain sensor demodulating system of current employing FFP (turnable fiber filter) technology.
Brief description of the drawings
Fig. 1 is the structural drawing of fiber grating strain pick-up unit of the present utility model;
Fig. 2 is the structural representation of acousto-optic tunable filter of the prior art.
Embodiment
Below in conjunction with accompanying drawing, several embodiments of the present utility model are described in detail, but are to be understood that protection domain of the present utility model is not subject to the restriction of embodiment.
In order to solve the problem that optical fiber grating regulating system demodulation speed is slow, light source bandwidth is little existing in prior art, the utility model proposes a kind of fiber grating strain pick-up unit.
As shown in Figure 1, fiber-optic grating detection device of the present utility model comprises: composite light source 10, coupling mechanism 20, optical circulator 30, acousto-optic tunable filter 40, conversion driving device 50, benchmark grating 60, photoswitch 70, fiber Bragg grating strain sensor 80, and composite light source 10 is of coupled connections with coupling mechanism 20; Coupling mechanism 20 is connected with benchmark grating 60 by optical circulator 30; Optical circulator 30 is connected with conversion driving device 50 by acousto-optic tunable filter 40; Benchmark grating 60 is connected with fiber Bragg grating strain sensor 80 by photoswitch 70.
Preferably, conversion driving device 50 comprises: photoelectric conversion module 501, signal processing module 502, radio-frequency driven controller 503, and acousto-optic tunable filter 40 is connected with signal processing module 502 by photoelectric conversion module 501; Radio-frequency driven controller 503 is connected with acousto-optic tunable filter 40, signal processing module 502 respectively.
Preferably, conversion driving device 50 also comprises operational amplification circuit 504, and photoelectric conversion module 501 is connected with signal processing module 502 by operational amplification circuit 504.
Preferably, composite light source 10 comprises the wideband light source of two different spectral ranges.
Preferably, coupling mechanism 20 is waveguide type fiber coupler 20.
Preferably, the angle of release of coupling mechanism 20 is in 30 °.
Preferably, optical circulator 30 is three ports light rings 30.
Preferably, acousto-optic tunable filter 40 comprises single axial birefringence crystal, piezoelectric transducer, high-frequency signal source, and piezoelectric transducer is bonded in a side of single axial birefringence crystal; High-frequency signal source carries out action of radio to piezoelectric transducer.
Preferably, photoelectric conversion module 501 is PIN photodiode.
Preferably, benchmark grating 60 is the fiber grating not encapsulating.
Fiber grating strain pick-up unit of the present utility model, composite light source 10 comprises the wideband light source of two different spectral ranges, the complex light of two different wave spectrum scopes is input to optical circulator 30 by coupling mechanism 20; Optical circulator 30 transmits complex light to benchmark grating 60, photoswitch 70, fiber Bragg grating strain sensor 80; The centre wavelength light signal that the centre wavelength light signal that fiber Bragg grating strain sensor 80 is reflected back reflects through photoswitch 70 and benchmark grating 60 is transferred to AOTF acousto-optic tunable filter 40 by optical circulator 30.
To photoelectric conversion module 501, carry out opto-electronic conversion by the light signal that regulates radio-frequency driven controller 503 can optionally export different wave length; By signal processing module 502, photoelectric conversion signal is carried out gathering after I-V conversion, filtering, amplification, image data is uploaded to outside master system, realize the demodulation of the centre wavelength of fiber Bragg grating strain sensor 80, outside host computer is according to fiber grating-strain detecting matching algorithm and then realize the strain measurement in sensor monitoring region.
Fiber grating strain pick-up unit of the present utility model is described as follows:
Composite light source 10, comprises wideband light source 101 and the wideband light source 102 of two different spectral ranges, and wideband light source 101 and wideband light source 102 are of coupled connections with the dual-port of coupling mechanism 20, and the light signal of the single port output of coupling mechanism 20 is composite light source 10.By compound the light source of two wave bands or multiple wave bands, form composite light source 10, solve because the limitation of light source causes the problem that current fiber grating strain sensor can not large-scale application.The less wave spectrum window combination of composite light source 10 selective light transmission exhaustion, meets light path design theory, meets the actual demand of fiber grating strain sensor.
Coupling mechanism 20, between optical fiber and optical fiber, to carry out the device that detachable (activity) is connected, it gets up accurate two end faces of optical fiber docking, go so that the luminous energy of launching fiber output can be coupled to receive in optical fiber to greatest extent, thereby and make it get involved the impact that optical link causes system to be reduced to minimum.
Preferably, coupling mechanism 20 can adopt waveguide type fiber coupler, and it is a kind of element with y-branch, can be with its decile in addition by the light signal of optical fiber input.In the time that the angle of release of 20 points of branch roads of coupling mechanism increases, will increase to the light leaking in covering, consequently increase loss, so the angle of release of coupling mechanism 20 is typically chosen in 30 °, therefore the length of waveguide type fiber coupler can not be too short.
Optical circulator 30, is the device of realizing the non-reversible transmission of light path, and it can guide reverse transfer light, itself and forward transmission light is separated from space, and exported from another port.Preferably, optical circulator 30 adopts three ports light rings to realize broadband optical signal transmitted in both directions and communicate by letter.
Acousto-optic tunable filter 40, acousto-optic tunable filter 40 (Acousto-optic tunable filter is called for short AOTF) is a kind of electro-optical modulation device.It is mainly to inciding the Bragg diffraction effect of the light in propagation medium while having utilized sound wave to propagate in anisotropic medium, as shown in Figure 2, acousto-optic tunable filter 40 can adopt acousto-optic tunable filter of the prior art, and by single axial birefringence crystal, (material conventionally adopting is tellurium dioxide (TeO
2), be bonded in the piezoelectric transducer of uniaxial crystal one side, and action of radio is in compositions such as the high-frequency signal sources of piezoelectric transducer.
In the time inputting the radiofrequency signal of certain frequency, acousto-optic tunable filter 40 can carry out diffraction to incident polychromatic light, therefrom selects the monochromatic light that wavelength is λ.Monochromatic wavelength X and rf frequency f have relation one to one, as long as can quick, randomly changing output light wavelength by the tuning of electric signal.Acousto-optic tunable filter 40 can be realized the demodulation of full spectral range, therefore this characteristic of acousto-optic tunable filter 40 is applied in fiber grating strain demodulation, has solved current fiber grating strain demodulation and has been difficult to the extensive problem realizing.
Acousto-optic tunable filter 40 can select any one wavelength coverage to carry out continuous sweep, can choose scanning according to effective wave band of tested optical fiber grating sensing, shorten sweep time, improved demodulation speed, solved the problem that current fiber grating strain demodulation is difficult to realization of High Speed; Acousto-optic tunable filter 40 is all solid state light-splitting device, without moving-member, anti-seismic performance is good, adopt hermetically sealed design, insensitive to environmental impact (as strain, humidity, dust etc.), instrument working stability, has solved the temperature drift problem of current fiber grating strain sensor demodulating system.
Conversion driving device 50, comprising: photoelectric conversion module 501, signal processing module 502, radio-frequency driven controller 503, operational amplification circuit 504.The function of photoelectric conversion module 501 is that the light signal of AOTF output is converted to electric signal, and the current signal after opto-electronic conversion can pass through operational amplification circuit 504, current signal is amplified to the current signal being amplified.Preferably, photoelectric conversion module 501 is PIN photodiode.
Signal processing module 502, the effect of signal processing module 502 comprises storage and the transmission of data acquisition, signal, to be transferred to master system, the strain of fiber grating data is processed.
Radio-frequency driven controller 503 is mainly AOTF (acousto-optic tunable filter) 40 designs, and the voltage of the signal of inputting by conditioning signal processing module 502, changes the output frequency of driving, and then affects the wavelength output of AOTF.
Operational amplification circuit 504, operational amplification circuit 504 (being called for short " discharge circuit ") is to have the very circuit unit of high-amplification-factor, for the current signal after photoelectric conversion module 501 conversions is amplified, obtains the current signal needing.
Benchmark grating 60, preferred, can adopt the not fiber grating of encapsulation.Fiber grating is the photosensitivity of utilizing fiber optic materials, incident light coherent field pattern is write fibre core by method by ultraviolet photoetching, in fibre core, produce along the axial refractive index cycle of fibre core and change, thereby form the phase grating in permanent space, its effect forms in fact an arrowband (transmission or reflection) wave filter or catoptron in fibre core.
Photoswitch 70, photoswitch 70 is a kind of optical device with one or more optional transmit pories, its effect is that the light signal in optical transmission line or integrated optical circuit is carried out to physics switching or logical operation.
Fiber Bragg grating strain sensor 80, can be by the strain information in the perception external world, and strain information is changed into the variation of fiber Bragg grating strain sensor 80 centre wavelengths.Fiber grating is the photosensitivity of utilizing fiber optic materials, by the method for ultraviolet photoetching, incident light coherent field pattern is write to fibre core, in fibre core, produce along the axial refractive index cycle of fibre core and change, thus the phase grating in formation space.In the time that fiber grating is subject to effect of stress, the centre wavelength of fiber grating will be drifted about, and can realize the demodulation of strain according to the strain sensing characteristic of fiber grating.
This kind of sensor is most widely used general in engineering field, the Fibre Optical Sensor that technology is the most ripe.Strain directly affects the wave length shift of fiber grating, and at working environment, the better or less sensor of structural requirement to be measured in the situation that, people directly stick on the surface for the treatment of geodesic structure or the inside that is embedded in structure using bare optical fibers and bare optical gratings as strain transducer.Because fiber grating is more fragile, in severe working environment, be very easy to destroy, thereby could use after need to encapsulating it.It is clipping that current conventional packaged type mainly contains substrate formula, tubular type and the two ends based on tubular type.
Fiber grating strain pick-up unit of the present utility model, optical fiber grating sensing, the demodulating system of the demodulation techniques design based on the full spectral range of AOTF (acousto-optic tunable filter), follow optical fiber grating sensing, the demodulating system based on FFP (turnable fiber filter) technology at present to compare, greatly improve sensing, the demodulation scope of system, solved the bottleneck problem of optical fiber grating sensing large-scale application.AOTF (acousto-optic tunable filter) 40 can select any one wavelength coverage to carry out continuous sweep, can choose scanning according to effective wave band of tested optical fiber grating sensing, shorten sweep time, solved the problem of optical fibre grating high-speed sensing and demodulating.AOTF is all solid state light-splitting device, without moving-member, anti-seismic performance is good, adopt hermetically sealed design, insensitive to environmental impact (as strain, humidity, dust etc.), instrument working stability, has solved the temperature drift problem of the fiber grating strain sensor demodulating system of current employing FFP (turnable fiber filter) technology.
Disclosed is above only several specific embodiment of the present utility model, and still, the utility model is not limited thereto, and the changes that any person skilled in the art can think of all should fall into protection domain of the present utility model.
Claims (10)
1. a fiber grating strain pick-up unit, it is characterized in that, comprise: composite light source, coupling mechanism, optical circulator, acousto-optic tunable filter, conversion driving device, benchmark grating, photoswitch, fiber Bragg grating strain sensor, described composite light source and described coupling mechanism are of coupled connections;
Described coupling mechanism is connected with described benchmark grating by described optical circulator; Described optical circulator is connected with described conversion driving device by described acousto-optic tunable filter; Described benchmark grating is connected with described fiber Bragg grating strain sensor by described photoswitch.
2. fiber grating strain pick-up unit according to claim 1, it is characterized in that, described conversion driving device comprises: photoelectric conversion module, signal processing module, radio-frequency driven controller, and described acousto-optic tunable filter is connected with described signal processing module by described photoelectric conversion module;
Described radio-frequency driven controller is connected with described acousto-optic tunable filter, described signal processing module respectively.
3. fiber grating strain pick-up unit according to claim 2, is characterized in that, described conversion driving device also comprises operational amplification circuit, and described photoelectric conversion module is connected with described signal processing module by described operational amplification circuit.
4. fiber grating strain pick-up unit according to claim 1, is characterized in that, described composite light source comprises the wideband light source of two different spectral ranges.
5. fiber grating strain pick-up unit according to claim 1, is characterized in that, described coupling mechanism is waveguide type fiber coupler.
6. according to the fiber grating strain pick-up unit described in claim 1-5 any one, it is characterized in that, the angle of release of described coupling mechanism is in 30 °.
7. fiber grating strain pick-up unit according to claim 1, is characterized in that, described optical circulator is three ports light rings.
8. fiber grating strain pick-up unit according to claim 1, it is characterized in that, described acousto-optic tunable filter comprises single axial birefringence crystal, piezoelectric transducer, high-frequency signal source, and described piezoelectric transducer is bonded in a side of described single axial birefringence crystal;
Described high-frequency signal source carries out action of radio to described piezoelectric transducer.
9. fiber grating strain pick-up unit according to claim 2, is characterized in that, described photoelectric conversion module is PIN photodiode.
10. fiber grating strain pick-up unit according to claim 1, is characterized in that, described benchmark grating is the fiber grating not encapsulating.
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| CN201420329382.8U CN203908511U (en) | 2014-06-19 | 2014-06-19 | Fiber bragg grating strain detection device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108680193A (en) * | 2018-04-18 | 2018-10-19 | 中山水木光华电子信息科技有限公司 | A kind of optical fiber code recognition methods based on light splitting matrix demodulation |
| CN112697061A (en) * | 2021-01-04 | 2021-04-23 | 无锡科晟光子科技有限公司 | Optical fiber strain system based on filter |
-
2014
- 2014-06-19 CN CN201420329382.8U patent/CN203908511U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108680193A (en) * | 2018-04-18 | 2018-10-19 | 中山水木光华电子信息科技有限公司 | A kind of optical fiber code recognition methods based on light splitting matrix demodulation |
| CN112697061A (en) * | 2021-01-04 | 2021-04-23 | 无锡科晟光子科技有限公司 | Optical fiber strain system based on filter |
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