CN103245299B - A kind of high spatial resolution optical fiber sensing system based on Wavelength tunable laser - Google Patents
A kind of high spatial resolution optical fiber sensing system based on Wavelength tunable laser Download PDFInfo
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- CN103245299B CN103245299B CN201310176696.9A CN201310176696A CN103245299B CN 103245299 B CN103245299 B CN 103245299B CN 201310176696 A CN201310176696 A CN 201310176696A CN 103245299 B CN103245299 B CN 103245299B
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Abstract
The invention discloses a kind of high spatial resolution optical fiber sensing system based on Wavelength tunable laser, comprise Wavelength tunable laser, piezoelectric ceramics, sawtooth voltage drives, first coupling mechanism, fibre optic interferometer, photodetector, Polarization Controller, second coupling mechanism, 3rd coupling mechanism, 4th coupling mechanism, Fibre Optical Sensor, photodetector, data collecting card, signal analysis and disposal system and computer display, wherein: the control port of Wavelength tunable laser connects the output port of piezoelectric ceramics, the control port of piezoelectric ceramics connects the output port of sawtooth voltage driving, the collection port of the output port connection data capture card of photodetector, the output access signal analysis of data collecting card and disposal system, the output port of signal analysis and disposal system is connected to computer display.There is high spatial resolution, distributed strain high precision on-line monitoring, stability and reproducible, sensitivity high.
Description
Technical field
The present invention relates to a kind of high spatial resolution frequency domain based on tunable wave length single longitudinal mode narrow linewidth Distributed Feedback Laser reflection Distributed Optical Fiber Sensing Techniques, the strain monitoring to structure and hi-Fix can be realized.
Background technology
Evaluation of structural safety is obtained and analytical structure internal information by various method for sensing, and make security judgement and early warning according to analysis result.Sensor at present for monitoring structural health conditions mainly comprises foil gauge, Fiber Bragg Grating FBG (FBG) sensor, the distributed fiberoptic sensor (BOTDR, BOTDA) of Brillouin scattering and traditional optical fiber frequency domain reflection technology OFDR etc.Experiment and engineering is actual shows, the Strain Distribution that foil gauge and optical fiber FBG sensor carry out spatially discrete point is measured, and cannot analyze structure collectivity.And the spatial resolution of BOTDR/BOTDA and traditional OFDA Fibre Optical Sensor can only reach at most tens centimetres, and strain measurement precision is not high, can not realize the distributed intelligence of accurate measurements structural strain and Efficient Evaluation health status.In many engineering structures, often requirement in very long measuring distance, while guarantee strain measurement precision, can realize the distributed strain of high spatial resolution, to meet structure whole and part monitoring and evaluation simultaneously.This is significant to the safety assessment of large scale structure.
Summary of the invention
Technical matters to be solved by this invention is for above-mentioned the deficiencies in the prior art, and a kind of high spatial resolution optical fiber sensing system based on Wavelength tunable laser is provided, on the sensor fibre of several kilometers even longer, can realize 2mm spatial resolution, and the precision of strain measurement simultaneously can reach 5 μ ε.This high-performance optical fiber sensor system can be used for structure distribution strain high precision test, measuring distance is long, spatial resolution and strain sensing precision high.
Technical scheme of the present invention is as follows:
A kind of high spatial resolution optical fiber sensing system based on Wavelength tunable laser, it is characterized in that: comprise Wavelength tunable laser, piezoelectric ceramics, sawtooth voltage drives, first coupling mechanism, fibre optic interferometer, first photodetector, Polarization Controller, second coupling mechanism, 3rd coupling mechanism, 4th coupling mechanism, Fibre Optical Sensor, second photodetector, data collecting card, signal analysis and disposal system and computer display, wherein: the control port of Single wavelength tunable laser connects the output port of piezoelectric ceramics, the control port of piezoelectric ceramics connects the output port of sawtooth voltage driving, the output of Wavelength tunable laser connects the input port of the first coupling mechanism, the input of one of them output port connecting fiber interferometer of the first coupling mechanism, and the output of fibre optic interferometer connects the input port of the first photodetector, the triggering collection port of the first photodetector output port connection data capture card, the another one output port of the first coupling mechanism connects the input of Polarization Controller, and the output of Polarization Controller connects the input of the second coupling mechanism, two output ports of the second coupling mechanism connect an input port of the 3rd coupling mechanism and the 4th coupling mechanism respectively, another input port of 3rd coupling mechanism is connected with the output port of Fibre Optical Sensor, first output port of the 3rd coupling mechanism is connected with the input port of described Fibre Optical Sensor, second output port of the 3rd coupling mechanism is connected with second input port of the 4th coupling mechanism, and the output port of the 4th coupling mechanism connects the input port of the second photodetector, the collection port of the output port connection data capture card of the second photodetector, the output access signal analysis of data collecting card and disposal system, the output port of signal analysis and disposal system is connected to computer display.
Described Wavelength tunable laser is the narrow band laser of single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser or based semiconductor technology or micro electro mechanical system (MEMS) technology.
When tunable laser wavelength starts scanning with certain speed, in optical fiber, each point all has scattered light appearance, the reference light sent when laser instrument and the scattered light beat frequency of optical fiber, there will be beat signal, gathered by high-speed inspection and analyze beat signal amplitude, frequency, phase place and correlativity, the sensing of high spatial resolution can be realized.
Compared with prior art, the present invention has high spatial resolution, distributed strain high precision on-line monitoring, stability and reproducible, sensitivity high.
Accompanying drawing explanation
Fig. 1 is a kind of concrete structure schematic diagram of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention is elaborated, but should not limit the scope of the invention with this.
As shown in Figure 1, sensing system of the present invention Wavelength tunable laser 1 used is single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser, and this single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser carries out particular design making for this sensor-based system.This single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser passes through phase-mask method, utilize excimer laser, on high concentration erbium doped fiber, first write segment length's Fiber Bragg Grating FBG, then secondary write is carried out on middle one section of grating, make it produce λ/4 phase shift, thus form er-doped λ/4 phase shifted distributed feedback DFB grating.Finally in conjunction with 980nm pump light, form single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser.This laser linewidth only has hundreds of hertz, has very long coherent length, therefore, it is possible to meet the frequency domain reflection distributed optical fiber sensing system requirement of long Distance function.By selecting appropriate phase mask plate, make the initial wavelength of laser instrument at about 1520nm.
Distributed feed-back DFB grating part in single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser is pasted on piezoelectric ceramics 2, drive 3 piezoelectric ceramics 2 is produced by sawtooth voltage to stretch, form periodic strain, realize the multiple scanning of wavelength in a wavelength range of optical fiber Distributed Feedback Laser.Single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser sends after the time dependent narrow-linewidth laser of wavelength enters the first coupling mechanism 4 and is divided into two-way, one tunnel enters fibre optic interferometer 5, when DFB optical maser wavelength changes, interferometer exports a series of interference peaks, interference of light peak is converted into pulse voltage after the first photodetector 6 detects, the triggering port of the output connection data capture card 13 of the first photodetector 6, realizes the passive triggering collection of data acquisition system (DAS).Another road laser is after Polarization Controller 7 eliminates polarization noise, again two-way is divided into after entering the second coupling mechanism 8, wherein a road enters the 3rd coupling mechanism 9 as sense light through the first input end mouth of the 3rd coupling mechanism 9, the first output port through the 3rd coupling mechanism 9 enters the input port of Fibre Optical Sensor 11, and the output port of Fibre Optical Sensor 11 enters the second input port of the 3rd coupling mechanism 9; Another road light then enters the 4th coupling mechanism 10 as with reference to light, interferes with the rear orientation light of sensor fibre.Interference light is gathered by data collecting card 13 after the second photodetector 12 detects, and finally utilizes signal analysis and disposal system 14 to carry out signal resolution and shows 15 eventually through computer.Single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser also can replace with the tunable wave length narrow band laser of based semiconductor technology or MEMS (micro electro mechanical system) (MEMS, Micro-Electro-MechanicalSystems) technology.
The two-way light that tunable wave length single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser sends, owing to entering Fibre Optical Sensor 11 and the 4th coupling mechanism 10 respectively, causes reference light different with the reflected light light path of sensor fibre, therefore interferes at the 4th coupling mechanism 10 place.Because laser wavelength is tunable, causing interference fringe to change, by paying sharp leaf spectrum analysis and digital signal processing, the frequency domain characteristic of interference fringe can be obtained.When the external world, strain changes, and the frequency domain characteristic of interference fringe also can respective change, and spatial resolution is also contained in the frequency domain information of interference fringe.The light source adopted due to dry systems is single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser, and its spatial coherence is very high, therefore by signal analysis and disposal system 14, just can realize the optical fiber frequency domain sensing technology of Large strain measuring accuracy and high spatial resolution thereof.
Claims (2)
1. the high spatial resolution optical fiber sensing system based on Wavelength tunable laser, it is characterized in that: comprise Wavelength tunable laser (1), piezoelectric ceramics (2), sawtooth voltage drives (3), first coupling mechanism (4), fibre optic interferometer (5), first photodetector (6), Polarization Controller (7), second coupling mechanism (8), 3rd coupling mechanism (9), 4th coupling mechanism (10), Fibre Optical Sensor (11), second photodetector (12), data collecting card (13), signal analysis and disposal system (14) and computer display (15), wherein: the control port of Single wavelength tunable laser (1) connects the output port of piezoelectric ceramics (2), the control port of piezoelectric ceramics (2) connects the output port that sawtooth voltage drives (3), the output of Wavelength tunable laser (1) connects the input port of the first coupling mechanism (4), the input of one of them output port connecting fiber interferometer (5) of the first coupling mechanism (4), the output of fibre optic interferometer (5) connects the input port of the first photodetector (6), the triggering collection port of the first photodetector (6) output port connection data capture card (13), the another one output port of the first coupling mechanism (4) connects the input of Polarization Controller (7), and the output of Polarization Controller (7) connects the input of the second coupling mechanism (8), two output ports of the second coupling mechanism (8) connect an input port of the 3rd coupling mechanism (9) and the 4th coupling mechanism (10) respectively, another input port of 3rd coupling mechanism (9) is connected with the output port of Fibre Optical Sensor (11), first output port of the 3rd coupling mechanism (9) is connected with the input port of described Fibre Optical Sensor (11), second output port of the 3rd coupling mechanism (9) is connected with second input port of the 4th coupling mechanism (10), and the output port of the 4th coupling mechanism (10) connects the input port of the second photodetector (12), the collection port of the output port connection data capture card (13) of the second photodetector (12), the output access signal analysis of data collecting card (13) and disposal system (14), the output port of signal analysis and disposal system (14) is connected to computer display (15).
2. the high spatial resolution optical fiber sensing system based on Wavelength tunable laser according to claim 1, is characterized in that: described Wavelength tunable laser is the narrow band laser of single longitudinal mode narrow linewidth optical fiber Distributed Feedback Laser or based semiconductor technology or micro electro mechanical system (MEMS) technology.
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| JP2003156315A (en) * | 2001-11-21 | 2003-05-30 | Mitsubishi Heavy Ind Ltd | Method and apparatus for measurement of distribution of strain and temperature |
| US7333680B2 (en) * | 2003-09-08 | 2008-02-19 | Fiberpro, Inc. | Fiber Bragg grating sensor system |
| CN102175170A (en) * | 2011-03-23 | 2011-09-07 | 东南大学 | Detecting method and sensor for cracks of civil structure based on optical fiber long chirped grating frequency domain reflection technology |
| CN202204524U (en) * | 2011-08-30 | 2012-04-25 | 杭州布里特威光电技术有限公司 | Distributed type optical fiber sensing device capable of simultaneously detecting Brillouin and Raman |
| CN102621101A (en) * | 2012-01-08 | 2012-08-01 | 杨少辰 | Laser visibility meter |
| CN203231735U (en) * | 2013-05-14 | 2013-10-09 | 东南大学 | High-spatial resolution fiber sensing system based on wavelength tunable laser |
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Patent Citations (6)
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| JP2003156315A (en) * | 2001-11-21 | 2003-05-30 | Mitsubishi Heavy Ind Ltd | Method and apparatus for measurement of distribution of strain and temperature |
| US7333680B2 (en) * | 2003-09-08 | 2008-02-19 | Fiberpro, Inc. | Fiber Bragg grating sensor system |
| CN102175170A (en) * | 2011-03-23 | 2011-09-07 | 东南大学 | Detecting method and sensor for cracks of civil structure based on optical fiber long chirped grating frequency domain reflection technology |
| CN202204524U (en) * | 2011-08-30 | 2012-04-25 | 杭州布里特威光电技术有限公司 | Distributed type optical fiber sensing device capable of simultaneously detecting Brillouin and Raman |
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