CN100526819C - Apparatus for measuring libration by optical fibre and measuring method - Google Patents
Apparatus for measuring libration by optical fibre and measuring method Download PDFInfo
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- CN100526819C CN100526819C CNB2006101294402A CN200610129440A CN100526819C CN 100526819 C CN100526819 C CN 100526819C CN B2006101294402 A CNB2006101294402 A CN B2006101294402A CN 200610129440 A CN200610129440 A CN 200610129440A CN 100526819 C CN100526819 C CN 100526819C
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Abstract
This invention discloses one fiber measurement vibration device and its test method, wherein, the device comprises DFB semiconductor laser, light ring device and its connected single mode fiber sensor, photoelectricity detector orderly connected to signal processor and current and temperature controller, wherein, the current and temperature controller and laser and cooling device are connected; the initial process of system is to determine laser temperature work point through amplifying and filtering photoelectricity output signals alternating volume as vibration signals to be tested.
Description
Technical field
The present invention relates to a kind of measuring vibrations method of optical fiber measurement vibrating device, belong to vibration measurement technique.
Background technology
Vibration survey has a wide range of applications in a lot of fields.These fields comprise that detection, seismic monitoring, the petroleum prospecting of sound and ultrasonic signal, the vibration-mode analysis and the water of various mechanical systems listens system etc.Present existing vibration transducer can be divided into types such as Electromagnetic Vibrating Sensor, variable displacement type vibration transducer and piezoelectric type vibration transducer by its principle difference.These vibration transducers all belong to electric transducer.Also have another kind of vibration transducer, i.e. optical fibre vibration sensor with electric transducer is corresponding.Compare optical fibre vibration sensor with electric transducer and have anti-electromagnetic interference (EMI), corrosion-resistant, long service life, volume is little, can the optical wavelength multiplexing mode realize significant advantages such as multiple spot distribution measuring, thereby bring into play huge effect in the occasion that can't use traditional electric transducer (as inflammable and explosive).Therefore in addition, optical fibre vibration sensor also has highly sensitive advantage, and in the many application that need survey the weak vibration signal, optical fibre vibration sensor has been brought into play crucial effect.The high sensitivity optical fiber vibration transducer adopts the fiber optic interferometric technology more, and all there is the problem that is subject to the external environment variable effect in the interference-type optical fiber sensor-based system, and for example, variation of temperature usually can cause the drift of interference-type optical fiber sensor-based system.And the main method that addresses this problem is exactly to adopt the compensation technique of certain mode.
Summary of the invention
Purpose of the present invention just provides a kind of measuring vibrations method of optical fiber measurement vibrating device.That the optical fiber measurement vibrating device that this method adopts has is simple in structure, be easy to implementation feature.Measuring method adopts feedback control technology to overcome the system drifting that temperature variation causes, and has fast, the highly sensitive characteristics of measuring process of frequency dynamic response.
The present invention is realized by following technical proposals, a kind of measuring vibrations method of optical fiber measurement vibrating device, described optical fiber measurement vibrating device, DFB (distributed feed-back) semiconductor laser 201 that comprises the butterfly encapsulation, semiconductor cooler 202 in the dfb semiconductor laser instrument, the other two ends of three end optical circulators, 204, the three end optical circulators that the dfb semiconductor laser output connects connect single-mode fiber 207 and photodetector 205 respectively; The single-mode fiber output terminal connects sensing head 100, and described sensing head comprises fibre core 102 and the semi-transparent semi-reflecting film 103 on the single-mode fiber end face and the micro-cantilever 104 of single-mode fiber; The output terminal of photodetector 205 connects signal processor 206 and electric current and temperature controller 203 successively, and the output terminal of electric current and temperature controller is connected with semiconductor cooler with the dfb semiconductor laser instrument, it is characterized in that comprising following process:
1. the initialization procedure of system, the dfb semiconductor laser instrument is arranged on predetermined firm power, continuously change the working temperature of semiconductor laser, its output wavelength of continuous tuning, the output of recording light electric explorer simultaneously, and the minimum value and the maximal value of definite output, obtain intermediate value and corresponding temperature spot thereof by minimum value and maximum value calculation.By of the temperature spot work of temperature controller control laser instrument in the intermediate value correspondence.
2. measuring process, the light that the dfb semiconductor laser instrument sends incides the vibration sensing head that is made of single-mode fiber and semi-girder through optical circulator, incident light is by the semi-transparent semi-reflecting membrane portions reflected back of single-mode fiber end face single-mode fiber, the light of transmission part incides on the micro-cantilever of single-mode fiber end face certain distance and afterwards is reflected, part optical signals in the reflected light is coupled in the single-mode fiber, form interference with the reflected light of single-mode fiber end face, and pass to optical circulator along single-mode fiber, pass to photodetector through optical circulator; The temperature of semiconductor laser makes it to follow the tracks of the slow variation of the DC component that is caused by the environmental change of vibration sensing head by the DC component FEEDBACK CONTROL of amplification and filtered photodetector output signal in the measuring process, reaches to make DC component stable; AC compounent through amplification and filtered photodetector output signal is tested vibration signal.
The principle of work of the fiber-optic vibration measuring system that the present invention relates to can further be explained as follows: the photo-signal that is produced by photodetector can be expressed as I=I
0+ I
1Exp[-(2L/L
c)
2] cos (4 π nL/ λ+π).Wherein, L is the distance between micro-cantilever and the single-mode fiber end face; L
cCoherent length for semiconductor laser; N is the refractive index of medium between micro-cantilever and the single-mode fiber end face; λ is an optical maser wavelength.So the photo-signal that photodetector produces is the sine function of L.L can be expressed as L=L
0+ δ L+ Δ L, wherein, δ L is the displacement that extraneous vibration causes micro-cantilever, generally speaking δ L＜＜L
0Δ L is the variation of distance between the micro-cantilever that causes of temperature or other factors and the single-mode fiber end face, δ L relatively, and Δ L is a gradual process.By selecting suitable L
0Can make of the response maximization of the photo-signal of photodetector generation with the value of λ to δ L, and in its range of linearity.So, adopt wave filter vibration signal can be separated from photo-signal with high pass characteristic.Adopting low-pass filter to cause the photo-signal that causes to change by temperature or other factors separates, and the temperature of FEEDBACK CONTROL semiconductor laser makes it wavelength shift, change to offset the photo-signal that causes by temperature or other factors, realize compensating action.
The invention has the advantages that, when the employing interference technique is realized the high-sensitivity detection of vibration, realized changing the drift that (for example variation of temperature) brings for the interference-type optical fiber sensor-based system by external environment.The dynamic frequency response of this Vibration-Measuring System, sensitivity can realize the vibration survey of high sensitivity and high-frequency response by the vibration characteristics of micro-cantilever and the frequency response decision of photodetector and signal processor by rational design.Method of the present invention in addition has the advantages that the Real-time and Dynamic of measuring system is demarcated.So the present invention can be applicable to the high sensitivity optical fiber nautical receiving set.
Description of drawings
Accompanying drawing 1 is by apparatus of the present invention structured flowchart.Among the figure: 201 is the dfb semiconductor laser instrument; 202 is semiconductor cooler; 203 is electric current/temperature controller; 204 is three end optical circulators; 205 is photodetector; 206 is signal processor; 207 is single-mode fiber; 100 is sensing head; 106 is vibratory output to be measured.
Accompanying drawing 2 is the structured flowchart by sensing head in apparatus of the present invention.Among the figure, 101 is the covering of single-mode fiber; 102 is the fibre core of single-mode fiber; 103 is the semi-transparent semi-reflecting film on the single-mode fiber end face; 104 is micro-cantilever; 105 substrates for fixing single-mode fiber and micro-cantilever; 106 is vibratory output to be measured.
Embodiment
Below in conjunction with accompanying drawing the specific embodiment of the present invention is elaborated.As shown in Figure 2, behind the end removal overlay with general single mode fiber, use the optical fiber cutting knife its end face to be cut into vertical with shaft axis of optic fibre.Adopt the optical coating technology that the semi-transparent semi-reflecting film (103) of 20-40% reflectivity can be arranged the light of 1550nm wave band in this end face plating one.The feature of the vibration signal that the material of micro-cantilever (104) and size can be measured is as required chosen and is designed.In the present embodiment, micro-cantilever 104 uses is micro-cantilever on the probe in the scanning probe microscopy, and material is a silicon nitride, is shaped as triangle, 200 microns of length, thickness 600nm.Optical fiber is aimed at micro-cantilever with the accurate adjustment rack of multidimensional at microscopically, with epoxy resin they are fixed on the quartz substrate 105, and obtain sensing head 100.
As shown in Figure 1, the 201 band single-mode tail fiber outputs of dfb semiconductor laser instrument, its inside is provided with semiconductor cooler 202, is that 25 ° of C and drive current are under the condition of 43mA in temperature, and its output wavelength and power are respectively 1553nm and 2mW.The output tail optical fiber of dfb semiconductor laser instrument 201 and 1 end of three end optical circulators 204 are joined, 2 ends of three end optical circulators 204 and the optical fiber of sensing head 100 are joined.The input tail optical fiber of 3 termination photodetectors 205 of three end optical circulators 204, in the present embodiment, photodetector 205 adopts the PIN pipe.By the signal of photodetector 205 output through signal processor 206 amplify and filtering after, input to electric current/temperature controller 203 as control signal.
After the system start-up, at first enter initialization.Dfb semiconductor laser instrument 201 is arranged on predetermined electric power, and this power is constant in measuring process.Electric current/temperature controller continuously changes the working temperature of semiconductor laser 201 in range of set temperature, to realize length scanning, adjacent minimum value and maximal value are determined in the direct current of tracer signal processor 206 output simultaneously.The difference of maximal value and minimum value is used for the calibration of measuring system.Obtain the working point that intermediate value and corresponding temperature thereof are determined system by minimum value and maximum value calculation.Electric current/temperature controller is arranged on this value with the temperature of laser instrument 201, and will be by the direct current output FEEDBACK CONTROL of signal processor 206.So far system finishes initialization procedure, enters the measurement state.
Tested vibration 106 causes the distortion of micro-cantilever 104, and makes the variation of distance L between micro-cantilever 104 and the single-mode fiber end face, i.e. δ L.δ L will cause the variation of the signal of photodetector 205 outputs, and this signal is after signal processor 206 amplifications and high-pass filtering, as the output of tested vibration signal.
Those skilled in the art are clear, and thought of the present invention can adopt the alternate manner beyond the above-named embodiment to realize.
Claims (1)
1. the measuring vibrations method of an optical fiber measurement vibrating device, described optical fiber measurement vibrating device, the distributed feedback semiconductor laser (201) that comprises the butterfly encapsulation, semiconductor cooler (202), three end optical circulators (204), sensing head (100), photodetector (205), signal processor (206), electric current and temperature controller (203) constitute, wherein, semiconductor cooler is arranged within the distributed feedback semiconductor laser of butterfly encapsulation, the output terminal of the distributed feedback semiconductor laser of butterfly encapsulation links to each other with three end optical circulators, an output terminal of three end optical circulators links to each other with sensing head by single-mode fiber (207), and described sensing head comprises the fibre core (102) of single-mode fiber, semi-transparent semi-reflecting film (103) on the single-mode fiber end face and micro-cantilever (104); Another output terminal of three end optical circulators connects photodetector, the photodetector output terminal connects signal processor, signal processor links to each other with temperature controller with electric current, electric current links to each other with semiconductor cooler with the distributed feedback semiconductor laser of butterfly encapsulation respectively with the temperature controller output terminal, it is characterized in that comprising following process:
1). the initialization procedure of system, distributed feedback semiconductor laser is arranged on predetermined firm power, continuously change the working temperature of semiconductor laser, its output wavelength of continuous tuning, the output of recording light electric explorer simultaneously, and the minimum value and the maximal value of definite output, obtain intermediate value and corresponding temperature spot thereof by minimum value and maximum value calculation, regulate and control laser instrument in this temperature value point work by electric current and temperature controller;
2). measuring process, the light that distributed feedback semiconductor laser sends incides the vibration sensing head that is made of single-mode fiber and micro-cantilever through optical circulator, incident light is by the semi-transparent semi-reflecting membrane portions reflected back of single-mode fiber end face single-mode fiber, the light of transmission part incides on the micro-cantilever of single-mode fiber end face certain distance and afterwards is reflected, part optical signals in the reflected light is coupled in the single-mode fiber, form interference with the reflected light of single-mode fiber end face, and pass to optical circulator along single-mode fiber, pass to photodetector through optical circulator; The temperature of the semiconductor laser that initialization is determined is by the DC component FEEDBACK CONTROL through amplification and filtered photodetector output signal, make it to follow the tracks of the slow variation of the DC component that causes by the environmental change of vibration sensing head, reach and make DC component stable; AC compounent through amplification and filtered photodetector output signal is tested vibration signal.
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| CNB2006101294402A CN100526819C (en) | 2006-11-16 | 2006-11-16 | Apparatus for measuring libration by optical fibre and measuring method |
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Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103139685B (en) * | 2012-12-18 | 2017-05-10 | 北京航天易联科技发展有限公司 | Audio signal processing device of optical fiber monitoring system |
| CN104266743B (en) * | 2014-10-22 | 2018-06-22 | 中国科学院电子学研究所 | Wavelength modulation optical fiber sonic transducer |
| CN104764476B (en) * | 2015-04-03 | 2017-05-03 | 大连理工大学 | Wavelength circulation tuning compensation interferential sensor operating point drift method |
| CN105628174B (en) * | 2016-01-08 | 2018-12-11 | 中国人民解放军国防科学技术大学 | Fibre-optical F-P sensor vibration demodulating system and method based on polarization switching |
| CN106680536A (en) * | 2016-10-20 | 2017-05-17 | 吉林大学 | High-sensitivity single polarization-maintaining fiber interference type acceleration speed sensing system |
| CN108318248B (en) * | 2017-01-16 | 2021-09-28 | 舍弗勒技术股份两合公司 | Optical fiber vibration sensing-based bearing state online monitoring system |
| CN107764744A (en) * | 2017-10-17 | 2018-03-06 | 湖南文理学院 | A kind of optical sensor for being applied to measurement physics and material property |
| CN108931291A (en) * | 2018-06-30 | 2018-12-04 | 东北石油大学 | A kind of contactless microvibration measuring system and method |
| CN110207806B (en) * | 2019-07-10 | 2021-10-26 | 国网上海市电力公司 | Oblique end face optical fiber vibration sensor and vibration measuring method thereof |
| CN111121945A (en) * | 2019-11-28 | 2020-05-08 | 上海电力大学 | High-sensitivity distributed transformer vibration monitoring system |
| CN111076803A (en) * | 2019-11-28 | 2020-04-28 | 上海电力大学 | High-sensitivity two-dimensional vibration monitoring sensing head |
| CN112033908B (en) * | 2020-07-30 | 2021-08-10 | 大连理工大学 | Single-light-source optical fiber photoacoustic gas sensing system and method |
| CN114894095B (en) * | 2022-03-04 | 2023-08-29 | 中国科学院合肥物质科学研究院 | Cantilever beam displacement measuring device and measuring method |
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2006
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| Diaphram-basedextrinsic Fabry-Perot interferometric optical fiber sensorfor acoustic wave detection under high background pressure. Ming Wang, etc.Optical Engineering,Vol.44 No.6. 2005 |
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