CN101603841A - A kind of fiber-optic grating sensor - Google Patents
A kind of fiber-optic grating sensor Download PDFInfo
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- CN101603841A CN101603841A CNA2008101249105A CN200810124910A CN101603841A CN 101603841 A CN101603841 A CN 101603841A CN A2008101249105 A CNA2008101249105 A CN A2008101249105A CN 200810124910 A CN200810124910 A CN 200810124910A CN 101603841 A CN101603841 A CN 101603841A
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Abstract
The present invention relates to a kind of fiber-optic grating sensor, comprise wideband light source, optical fiber, the wave filter of fixed wave length, detector and the fiber grating that is used to monitor the physical quantity variation that is positioned at measurement point, it is characterized in that: the wave filter of-fixed wave length, only allow a narrow optical wavelength band to pass through, pass through and limit other wavelength, and the wavelength band that its permission is passed through is not in the reflection wavelength band of fiber grating, and have the preset wavelength difference with described reflection wavelength,-wideband light source injects surveys light, when monitored physical quantity variation reaches certain value, be positioned at the preset wavelength difference that the reflection wavelength band of the fiber grating of measurement point has drifted about above-mentioned, thereby the wavelength band that the wave filter that makes this reflection wavelength band and fixed wave length allows to pass through intersects, at this moment, in the reflected light signal of fiber grating, have at least a part to arrive detector, thereby detect the variation of described physical quantity by the wave filter of fixed wave length.
Description
Affiliated technical field
The present invention relates to a kind of fiber-optic grating sensor, is the sensor of surveying by optical fiber and fiber grating, surveys the method that physical quantity changes, and this physical quantity can be temperature or the like, and this method belongs to field of sensing technologies.
Background technology
We know that optical fiber is the passage of light conducting signal, because its design feature, optical fiber is very responsive to residing environment, as variation of temperature, optical fiber are shunk, and the result causes it that the variation that detects easily takes place, as the decay increase of light signal.When optical fiber is subjected to mechanical stress, pressure variation, electric field or changes of magnetic field, also above-mentioned variation can take place, therefore, many known sensors are with the variation of fiber-optic probe physical quantity.In this sensor of a part, use fiber grating, relatively be typically Bragg grating.Below we are called Bragg grating with fiber grating, but be not that application of the present invention is only only limited to Bragg grating.
Bragg grating is selected reverberator as a kind of wavelength, the wavelength of reflectance spectrum (being the reflection wavelength band) can be subjected to the influence of STRESS VARIATION and produce mobile, by the monitoring of reflection wavelength Tape movement promptly being known the situation of change of physical quantity.Existing Bragg grating proving installation is to utilize wideband light source to be injected into Bragg grating, and the measurement of the reflected light signal wavelength change of light source being carried out according to Bragg grating, but this method needs expensive instrument that reflection wavelength is carried out demodulation to be determined, this device comprises wideband light source and complicated Wavelength demodulation device, make this device Yin Gaoang in practical engineering application cost and be restricted.
Summary of the invention
The objective of the invention is to formulate the sensor of a kind of use fiber grating (as Bragg grating), to avoid above-mentioned defective.
For this reason, the present invention proposes a kind of fiber-optic grating sensor, comprise wave filter, the detector of wideband light source, optical fiber, fixed wave length and be placed on the optical fiber be positioned at measurement point be used to monitor the fiber grating that physical quantity changes, it is characterized in that:
The wave filter of-fixed wave length only allows a narrow optical wavelength band to pass through, pass through and limit other wavelength, and the wavelength band that its permission is passed through is in the reflection wavelength band of fiber grating, and has the preset wavelength difference with described reflection wavelength,
-wideband light source injects detection light from the so-called incident end of optical fiber, when monitored physical quantity variation reaches certain value, the reflection wavelength that is positioned at the fiber grating of measurement point brings to few preset wavelength difference of having drifted about above-mentioned, thereby make this reflection wavelength bring to the part that few wave filter that has covered fixed wave length allows the wavelength band that passes through, at this moment, the fiber grating of this measurement point is to the reflected light signal of the detection light signal generating of wideband light source incident, at least a portion reflected light signal can arrive detector by the wave filter of fixed wave length, thereby detects the variation of described physical quantity.
The present invention surveys to be monitored a kind of fiber-optic grating sensor that physical quantity changes, it is the variation that has utilized reflected light signal, determine the variation of the physical quantity of described measurement point: if variation has taken place near the physical quantity of being monitored a fiber grating, and the variation that takes place has reached the degree that we are concerned about, at this moment the reflection wavelength of fiber grating brings to few preset wavelength difference of having drifted about, thereby make this reflection wavelength bring to the part that few wave filter that has covered fixed wave length allows the wavelength band that passes through, at this moment, the fiber grating of this measurement point is just to the reflected light signal of the detection light signal generating of wideband light source incident, at least a portion reflected light signal can arrive detector by the wave filter of fixed wave length, this explanation has stress to exist, thereby may detect the variation of respective physical amount.
In actual engineering, we usually only need obtain the data that a part of physical quantity changes, just can reach our target, in the fire temperature warning system, we press for understanding to the state of temperature below 25 ℃ the time, we only need to set a monitoring, alarming temperature, as 65 ℃, then as the fiber grating on the optical fiber of sensor, measure this fiber grating in the time of 65 ℃ the reflection wavelength band and choose a wavelength band, the wave filter of the fixed wave length that this wavelength band of a permission of arrangement passes through before detector, described fiber grating is when normal temperature (as 20 ℃), the wavelength that the wave filter of the wavelength band of the light signal of its reflection and the fixed wave length of installation allows to pass through has wavelength difference, at this moment Fan She light signal can not be by the wave filter of fixed wave length, detector will be surveyed less than light signal, this sensor is installed in the place of monitoring, as warehouse etc., under normal conditions, environment temperature generally can not reach 65 ℃, detector is surveyed less than light signal, have only when the temperature of measurement point near or when reaching 65 ℃, the fiber grating reflection wavelength band of this measurement point will drift about and allow the wavelength band juxtaposition that passes through with the wave filter of fixed wave length, at this moment, can have the wave filter of the light signal of part reflection at least by fixed wave length, arrive detector, can monitor tangible light signal on the detector, thereby triggered the fire temperature alert if, reached the purpose of monitoring.
Above-mentioned example, also can realize with the system that wide light source and Wavelength demodulation device are formed, this system data of all fiber gratings under the continuous substantially temperature between can obtaining from normal temperature to the alarm temperature, then the temperature of measurement point near or report to the police when reaching alarm temperature, this system testing has obtained the data that have little significance in a large number as can be seen, and expensive instrument also is higher to maintenance requirement.So in similarity,, obviously be uneconomic with respect to the monitoring system that adopts the inventive method with the monitoring system that wide light source and complicated Wavelength demodulation device are formed.
Under actual engineering specifications, a value of only monitoring physical quantity usually is not enough, so the wave filter of a plurality of fixed wave length can be set, it allows different optical wavelength bands to pass through, and the wavelength band that its permission is passed through is in the reflection wavelength band of fiber grating, and has different preset wavelength differences with described reflection wavelength, thereby can detect a plurality of values that the measurement point physical quantity changes, the trend that changes of measurement point physical quantity as can be seen simultaneously is so that better monitoring.
Can a plurality of fiber gratings be set respectively at a plurality of measurement points on the optical fiber, and fiber grating has essentially identical reflection wavelength band, thus the variation of measuring the physical quantity of a plurality of points.And can determine the position of vicissitudinous measurement point according to reflected light signal and time relation.
Description of drawings:
Fig. 1 is that the wave filter of reflectance spectrum, a fixed wave length of a Bragg grating of expression allows the spectrum that passes through and both graphs of a relation;
Fig. 2 is the structured flowchart of the fiber-optic grating sensor of relevant first embodiment of the present invention of expression;
Fig. 3 is the structured flowchart of the fiber-optic grating sensor of relevant second embodiment of the present invention of expression;
Fig. 4 is the structured flowchart of the fiber-optic grating sensor of relevant the 3rd embodiment of the present invention of expression;
Among the figure: 3 one wideband light sources,
4,9 one optical branching devices,
5,5a, 5b, 5n one fiber grating,
6,6a, 6b, 6n one photo-detector,
7 one optical fiber,
10,10a, 10b, the wave filter of 10n one fixed wave length.
Embodiment
Curve 1 among Fig. 1 has schematically shown the reflectance spectrum of a Bragg grating, λ
1And λ
2Be respectively the lower limit and the upper limit wavelength of this Bragg grating reflection wavelength, all wavelength all are the wavelength that Bragg grating can reflect in these two wavelength, are called the reflection wavelength band here.The wave filter that curve 2 has schematically shown a fixed wave length allows the spectrum that passes through, λ
3And λ
4Be respectively the lower edge and the upper edge wavelength of this wavelength band, λ
2And λ
3Between distance be exactly that described preset wavelength is poor.
First embodiment
Fig. 2 is the structured flowchart of the fiber-optic grating sensor of expression first embodiment.The fiber-optic grating sensor of first embodiment by the wave filter 10 of wideband light source 3, photo-detector 6, optical branching device 4, fixed wave length, be positioned at measurement point and be used to monitor fiber grating 5 and the optical fiber 7 that physical quantity changes and constitute.Connect with optical fiber between each parts.Optical branching device 4 can be 2 shunting couplers, also can be optical circulator.
The wavelength band that wave filter 10 permissions of fixed wave length are passed through and the reflection wavelength of fiber grating 5 have a default difference, pass through optical branching device 4 and optical fiber 7 from the detection light signal of wideband light source 3 outputs, and reach fiber grating 5, the detection light signal that 5 pairs of wideband light sources of fiber grating 3 inject has narrow band light reflection, the light signal of reflection arrives the wave filter 10 of fixed wave length through optical branching device 4 and optical fiber 7, at monitored physical quantity no change or change when not reaching the degree that we are concerned about, the wavelength of reflected light signal is not in the wavelength band that the wave filter 10 of fixed wave length allows to pass through, promptly at this moment reflected light signal can not be by the wave filter 10 of fixed wave length, and detector does not detect light signal; When the physical quantity of monitored point changes to the degree of our care, the reflection wavelength that is positioned at the fiber grating 5 of described measurement point brings to few described preset wavelength difference of having drifted about, promptly the fiber grating reflection wavelength band of this measurement point just has juxtaposition with the wavelength that the wave filter permission of fixed wave length is passed through, at this moment, can have the wave filter of the light signal of part reflection at least by fixed wave length, arrive detector, can monitor tangible light signal on the detector, thereby detect the variation of physical quantity.
Second embodiment
Fig. 3 is the structured flowchart of the fiber-optic grating sensor of expression second embodiment.The fiber-optic grating sensor of second embodiment by the wave filter 10n of the wave filter 10b of the wave filter 10a of wideband light source 3, photo-detector 6a, photo-detector 6b, photo-detector 6n, optical branching device 4, optical branching device 9, fixed wave length, fixed wave length, fixed wave length, be positioned at measurement point and be used to monitor fiber grating 5 and the optical fiber 7 that physical quantity changes and constitute.Connect with optical fiber between each parts.Optical branching device 4 can be 2 shunting couplers, also can be optical circulator.
Detection light signal from wideband light source 3 outputs, the detection light signal that 5 pairs of wideband light sources of fiber grating 3 inject has narrow band light reflection, the light signal of reflection is through optical branching device 4, optical branching device 9 and optical fiber 7 arrive the wave filter 10a of fixed wave length, the wave filter 10b of fixed wave length and the wave filter 10n of fixed wave length, the wave filter 10a of fixed wave length, the wave filter 10b of fixed wave length, the wavelength band that the wave filter 10n of fixed wave length has different permissions to pass through, and have different preset difference values with the reflection wavelength of fiber grating 5, the variation of monitored physical quantity can cause the drift of the reflection wavelength band of fiber grating 5, when preset wavelength difference that the reflection wavelength band has drifted about different, photo-detector 6a, photo-detector 6b, photo-detector 6n can detect tangible light signal, and we just can detect a plurality of values that physical quantity changes.
The 3rd embodiment
Fig. 4 is the structured flowchart of the fiber-optic grating sensor of expression the 3rd embodiment.The fiber-optic grating sensor of the 3rd embodiment by wave filter 10, photo-detector 6, the optical branching device 4 of wideband light source 3, fixed wave length, be positioned at measurement point and be used to monitor fiber grating 5a, fiber grating 5b, fiber grating 5n and the optical fiber 7 that physical quantity changes and constitute.Connect with optical fiber between each parts.Optical branching device 4 can be 2 shunting couplers, also can be optical circulator.
Detection light signal from wideband light source 3 outputs, by optical branching device 4 and optical fiber 7, and reach fiber grating 5a with basic identical reflection wavelength band, fiber grating 5b, fiber grating 5n, the wave filter 10 of fixed wave length allows the wavelength band and the fiber grating 5a that pass through, fiber grating 5b, the reflection wavelength of fiber grating 5n has a default difference, cause the drift of the reflection wavelength band of fiber grating when the variation of the monitored physical quantity that is positioned at certain measurement point, and when the reflection wavelength band has drifted about described preset wavelength difference, just have reflected light by optical fiber 7, optical branching device 4, wave filter 10 by fixed wave length enters into photo-detector 6, and we just can detect the variation of physical quantity like this; When we according to reflected light that enters into photo-detector 6 and time relation, just can determine to take place the position of the fiber grating that physical quantity changes, thereby determine to take place the position that physical quantity changes.
As seen, the method according to detection of the present invention is simpler than the method for prior art.
Certainly, the present invention is not limited to the embodiment that the front is introduced, and we can replace whole device with another kind of equivalent arrangements, and do not exceed scope of the present invention.
Claims (4)
1. fiber-optic grating sensor, comprise wave filter, the detector of wideband light source, optical fiber, fixed wave length and be placed on the optical fiber be positioned at measurement point be used to monitor the fiber grating that physical quantity changes, it is characterized in that:
The wave filter of-fixed wave length only allows a narrow optical wavelength band to pass through, pass through and limit other wavelength, and the wavelength band that its permission is passed through is in the reflection wavelength band of fiber grating, and has the preset wavelength difference with described reflection wavelength,
-wideband light source injects detection light from the so-called incident end of optical fiber, when monitored physical quantity variation reaches certain value, the reflection wavelength that is positioned at the fiber grating of measurement point brings to few preset wavelength difference of having drifted about above-mentioned, thereby make this reflection wavelength bring to the part that few wave filter that has covered fixed wave length allows the wavelength band that passes through, at this moment, in the reflected light signal of the fiber grating of this measurement point to the detection light signal generating of wideband light source incident, have at least a part of reflected light signal to arrive detector, thereby detect the variation of described physical quantity by the wave filter of fixed wave length.
2. a kind of fiber-optic grating sensor according to claim 1, it is characterized in that: the wave filter that a plurality of fixed wave length can be set, it allows different optical wavelength bands to pass through, and the wavelength band that its permission is passed through is not in the reflection wavelength band of fiber grating, and have different preset wavelength differences, thereby can detect a plurality of values that the measurement point physical quantity changes with described reflection wavelength.
3. a kind of fiber-optic grating sensor according to claim 1 and 2 is characterized in that: can a plurality of fiber gratings be set respectively at a plurality of measurement points on the optical fiber, and these fiber gratings have essentially identical reflection wavelength band.
4. a kind of fiber-optic grating sensor according to claim 3, it is characterized in that: according to the reflected light signal and the time relation of the wave filter that passes through fixed wave length, the position of vicissitudinous fiber grating can be determined, thereby the position that changes physical points can be defined.
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| CNA2008101249105A CN101603841A (en) | 2008-06-11 | 2008-06-11 | A kind of fiber-optic grating sensor |
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| CNA2008101249105A CN101603841A (en) | 2008-06-11 | 2008-06-11 | A kind of fiber-optic grating sensor |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102859332A (en) * | 2010-01-25 | 2013-01-02 | 费劳恩霍夫应用研究促进协会 | Sensor element and method for the production thereof and use thereof |
| CN103148880A (en) * | 2013-03-01 | 2013-06-12 | 黑龙江大学 | Color-filter-based multi-channel fiber bragg grating demodulator |
| 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 |
| CN109270320A (en) * | 2018-10-31 | 2019-01-25 | 江苏骏龙光电科技股份有限公司 | A kind of fiber grating measuring device can be used for transmission line of electricity |
-
2008
- 2008-06-11 CN CNA2008101249105A patent/CN101603841A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102859332A (en) * | 2010-01-25 | 2013-01-02 | 费劳恩霍夫应用研究促进协会 | Sensor element and method for the production thereof and use thereof |
| CN102859332B (en) * | 2010-01-25 | 2016-01-06 | 费劳恩霍夫应用研究促进协会 | Sensor element and manufacture method thereof and usage |
| CN103148880A (en) * | 2013-03-01 | 2013-06-12 | 黑龙江大学 | Color-filter-based multi-channel fiber bragg grating demodulator |
| CN103148880B (en) * | 2013-03-01 | 2015-04-08 | 黑龙江大学 | Color-filter-based multi-channel fiber bragg grating demodulator |
| 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 |
| CN109270320A (en) * | 2018-10-31 | 2019-01-25 | 江苏骏龙光电科技股份有限公司 | A kind of fiber grating measuring device can be used for transmission line of electricity |
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Addressee: Xi'an Jinhe Optical Technology Co., Ltd. Document name: Notification of Patent Invention Entering into Substantive Examination Stage |
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Application publication date: 20091216 |