CN1292238C - Optical fiber vibrative sensor based on optical fiber raster - Google Patents
Optical fiber vibrative sensor based on optical fiber raster Download PDFInfo
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- CN1292238C CN1292238C CN 200410066814 CN200410066814A CN1292238C CN 1292238 C CN1292238 C CN 1292238C CN 200410066814 CN200410066814 CN 200410066814 CN 200410066814 A CN200410066814 A CN 200410066814A CN 1292238 C CN1292238 C CN 1292238C
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- optical fiber
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Abstract
The present invention relates to an optical fiber microvibration sensor based on an optical fiber grating. The present invention uses the resonance of a suspended Bragg optical fiber grating and an object to be measured to amplify the vibration amplitude of the measured object, and the present invention can carry out the measurement of wavelength type modulation or strength type modulation. Two interfaces at one end of a 2*2 coupler are respectively connected with a broadband light source and a spectrum analyzer or a light power meter, and two interfaces at the other end are respectively connected with matching liquid and a transmission optical fiber. The transmission optical fiber penetrates through a connector and to enter an insulative cylinder and is fixed to the central position of the insulative cylinder by a connection head. The suspended Bragg optical fiber grating for resonance is engraved at one end of transmission optical fiber in the insulative cylinder. In the structure adopting the spectrum analyzer to carry out the measurement of wavelength type modulation, a calibration Bragg optical fiber grating for calibrating the central wavelength of the reflection light of a vibration balancing position is engraved at a section of transmission optical fiber at an ingress of the connector. The present invention solves the problem of cross sensitivity of the optical fiber grating. The present invention can carry out the measurement of microvibration of large instruments under the conditions of strong electromagnetic field and high voltage.
Description
Technical field
The present invention relates to a kind of optical fiber vibrative sensor, be mainly used in little vibration displacement and the little vibration velocity of measuring measured object, belong to photoelectron test class field based on fiber grating.
Background technology
Large-scale instrument has microvibration when work, the amplitude of this vibration can not surpass certain scope under the normal condition, and when the instrument abnormal work, vibration also can be unusual.People wish to understand the concrete size of this vibration under a lot of situations, so that obtain the critical value of abnormal vibrations, take measures to get rid of equipment generation major accidents such as instrument, flight or running.
Have a lot of occasions to require the measurement sensing probe of little vibration can not be charged, can work under the environment of electromagnetic interference (EMI), it must be online detection that ask for something is arranged, and just under the environment of actual needs measuring method is proposed new requirement.And optical fibre vibration sensor can be worked under the environment of electromagnetic interference (EMI) owing to the characteristic that optical fiber itself has anti-electromagnetism, anti-irradiation, and this is that the electric oscillation sensor is incomparable.
The patent No. is 94202968.2 Chinese patent " passive non-metallic fiber vibration sensing head ", adopt following vibration measuring method: optical fiber vibration sensing head has three optical fiber, one is incident optical, and other two is outgoing optical fiber, and three optical fiber link to each other with GRIN Lens.When sensing head did not vibrate, light was mapped to by GRIN Lens on the catoptron that has spring leaf, and light returns once more by being distributed on two outgoing optical fiber that GRIN Lens is equal to, and at this moment, the output power of two outgoing optical fiber is the same; When sensing head vibrated, catoptron also can be along with vibration, and the luminous power of reflected light distribution on two outgoing optical fiber will be variant like this, can measure the vibration displacement of UUT thus.This optical fiber vibration sensing head seems simply, but has obvious defects, be not that each vibration position can both guarantee reflected light by the output of outgoing optical fiber, and sensitivity is not high.
The patent No. is 01112717.1 Chinese patent " method of optical fiber resonance micrometer vibration ", utilize the resonance of suspension optical fiber and UUT that its Oscillation Amplitude is amplified, by the camera CCD that is placed on fiber-optic vibration end front portion (Charge Coupled Device) the fiber-optic vibration situation is filmed, CCD is transferred to computing machine or terminal by image pick-up card and handles and show then.This way resolution is very high, and have the real-time online measuring ability, but shortcoming cannot be measured resonant frequency exactly, can only measure under the prerequisite of knowing resonant frequency in advance, and resonant frequency has some deviations a little when measuring, and will influence the precision of this sensor.
Summary of the invention
The objective of the invention is at the deficiencies in the prior art, propose a kind of optical fiber vibrative sensor, promptly improve the performance of original vibration transducer, make manufacture craft become simple relatively again based on fiber grating.
For realizing such purpose, the resonance that the present invention utilizes sensing probe fiber grating and measured object is amplified the Oscillation Amplitude of measured object, by the luminous power or the wavelength of measuring optical fiber optical grating reflection light, accurately measure the Oscillation Amplitude and the vibration velocity of measured object.Fiber grating when resonance, square being inversely proportional to, being inversely proportional to of the natural frequency of fiber grating and optical fiber raster vibration length with the fiber grating radius, this is the main theory foundation according to resonant frequency making matched fiber grating.
Optical fiber vibrative sensor of the present invention comprises the suspension bragg grating, insulating concrete cylinder, calibration bragg grating, connector, connector, matching fluid, wideband light source, 2 * 2 coupling mechanisms, spectroanalysis instrument or light power meter and Transmission Fibers etc.2 * 2 a coupling mechanisms wherein interface of an end connect wideband light source with optical fiber, and another interface connects spectroanalysis instrument with optical fiber, and two interfaces of an other end connect matching fluid and Transmission Fibers respectively with optical fiber.
One end of the insulating concrete cylinder of hollow is with the connector that is threaded, Transmission Fibers is passed connector and is entered insulating concrete cylinder, and be fixed on the center of insulating concrete cylinder by connector, the end of Transmission Fibers in insulating concrete cylinder is carved with the suspension bragg grating of the usefulness that is used to resonate, the intersection of suspension bragg grating and connector is affixed with glue,, have in the internal thread of externally threaded connector precession insulating concrete cylinder one end with in the connector of internal thread with externally threaded connector precession.One section Transmission Fibers of connector inflow point is carved with the calibration bragg grating that is used to demarcate vibration balancing position reflected light centre wavelength.
The length of suspension bragg grating too weak point can cause Oscillation Amplitude smaller, influences the precision of sensor; And the oversize meeting of length causes the gravity of fiber grating itself to make the bending of suspension fiber grating excessive, influences the mensuration of resonant frequency, so length is generally got 20-80mm.It is too little and cannot detect that the too small meeting of the diameter of suspension bragg grating causes transmitting the power of light; And diameter is crossed conference and is caused Oscillation Amplitude too small, makes the resolution of sensor and sensitivity reduce, so diameter is generally got 0.1-0.8mm.Be engraved in two sections fiber gratings on the Transmission Fibers, one section is the suspension bragg grating in the Transmission Fibers end, and another section is the calibration bragg grating at the Transmission Fibers medium position, and the reflected light centre wavelength of these two sections fiber gratings is identical.
If will connect the interface reconfiguration light power meter of spectroanalysis instrument in 2 * 2 coupling mechanisms of the present invention, and one section Transmission Fibers of connector inflow point no longer is carved with the calibration bragg grating that is used to demarcate vibration balancing position reflected light centre wavelength, then can constitute another kind of version of the present invention.
Utilize these two kinds of structures of the present invention to carry out the optical fiber microvibration measuring and can adopt two kinds of forms:
First kind of structure is directly proportional with the Oscillation Amplitude of bragg grating based on the relative drift of bragg grating reflected light centre wavelength, Oscillation Amplitude is converted to the relative drift value of optical wavelength, receiving terminal detects with spectroanalysis instrument, detection of reflected center wavelength of light period of change can record the vibration frequency of UUT simultaneously, and then can acquire the vibration velocity of UUT.The sensor that experimental debugging is good is fixed on the UUT that has fixing vibration frequency, during work, incident light through coupling mechanism to the suspension bragg grating, because the self character of suspension bragg grating, the light that a part has certain wavelength can be reflected, and suspension bragg grating when vibration, catoptrical centre wavelength can change along with oscillation amplitude change, and last spectroanalysis instrument detects, shows and export the reflected light through coupling mechanism.
Relative first kind of structure, second kind of structure lacked the calibration bragg grating, by the reflected optical power P of sense cycle internal vibration amplitude maximum rating
1Reflected optical power P with equilibrium state
2, they are both ratio P
1/ P
2Become certain proportional relation with Oscillation Amplitude, simultaneously detection of reflected luminous power P
1With P
21/4 cycle of UUT vibration just in the time interval, the ratio by amplitude and time can obtain vibration velocity.Duty and first kind are similar, and only terminal is handled with light power meter, also can become voltage to light signal light by opto-electronic conversion, carries out electrical signal detection, processing, demonstration and output by single-chip microcomputer or computing machine then.
Suspension bragg grating of the present invention both can be that an end is fixed, other end beam vibration freely, also can be the beam vibration that two ends are all fixed.
The resonance that the present invention utilizes suspension bragg grating and measured object is amplified the Oscillation Amplitude of measured object, enlargement factor is about 100 times, sensitivity can reach 0.01mm, can not only detect under resonance state, and can also detect near resonance state.The invention solves the problem of fiber grating cross sensitivity, solved the problems of measurement of the little vibration of large-scale instrument under strong-electromagnetic field, high voltage environment, but also temperature that can the surveying work environment.The present invention can measure information such as the vibration displacement of UUT and vibration velocity simultaneously, utilizes light power meter or spectroanalysis instrument, single-chip microcomputer or computer equipment output to show, thereby can carry out real time and on line monitoring; Can measure the Oscillation Amplitude in one section vibration frequency range; Making is simple, cost is lower, be fit to batch process.
Description of drawings
Fig. 1 is the structural representation that the present invention is based on the optical fiber vibrative sensor of fiber grating.
Among Fig. 1: 1-suspension bragg grating, the 2-insulating concrete cylinder, 3-calibrates bragg grating, 4-connector, 5-connector, 6-matching fluid, 7-wideband light source, 8-spectroanalysis instrument, 9-2 * 2 coupling mechanisms.
Fig. 2 is the another kind of structural representation that the present invention is based on the optical fiber vibrative sensor of fiber grating.
Among Fig. 2: the 10-light power meter.
Embodiment
Below in conjunction with accompanying drawing technical scheme of the present invention is further described.
A kind of structure such as Fig. 1 of optical fiber vibrative sensor of the present invention comprise suspension bragg grating 1, insulating concrete cylinder 2, calibration bragg grating 3, connector 4, connector 5, matching fluid 6, wideband light source 7,2 * 2 coupling mechanisms 9, spectroanalysis instrument 8 and Transmission Fibers etc.Connected mode of the present invention: the A of 2 * 2 coupling mechanisms 9
1Port links to each other A with wideband light source 7
2Port links to each other B with spectroanalysis instrument 8
1Port links to each other B with matching fluid 6
2Port links to each other with Transmission Fibers.
One end of the insulating concrete cylinder 2 of hollow is with the connector 4 that is threaded, Transmission Fibers is passed connector 4 and is entered insulating concrete cylinder 2, and be fixed on the center of insulating concrete cylinder 2 by connector 5, the end of Transmission Fibers in insulating concrete cylinder 2 is carved with the suspension bragg grating 1 of the usefulness that is used to resonate, suspension bragg grating 1 is affixed with glue with the intersection of connector 5,, have in the internal thread of externally threaded connector 4 precession insulating concrete cylinders 2 one ends with in the connector 4 of internal thread with externally threaded connector 5 precessions.One section Transmission Fibers of connector 4 inflow points is carved with the calibration bragg grating 3 that is used to demarcate vibration balancing position reflected light centre wavelength.
Another kind of structure of the present invention wherein, is the A in 2 * 2 coupling mechanisms 9 with the difference of structure shown in Figure 1 as shown in Figure 2
2Port is not to connect spectroanalysis instrument 8, but links to each other with light power meter 10, and the Transmission Fibers of connector 4 inflow points is not carved with calibration bragg grating 3 yet.
Utilize the present invention to carry out the optical fiber microvibration measuring and can adopt two kinds of forms:
The modulation system of the present invention's structure shown in Figure 1 belongs to the modulation of light wavelength type.The relative drift that the measuring principle of this structure is based on suspension bragg grating 1 reflected light centre wavelength is directly proportional with the Oscillation Amplitude of suspension bragg grating 1, Oscillation Amplitude is converted to the relative drift value of optical wavelength, receiving terminal detects with spectroanalysis instrument 8, detecting the 1 reflected light center wavelength variation cycle of suspension bragg grating simultaneously can record the vibration frequency of UUT, and then can obtain the vibration velocity of UUT.The sensor that experimental debugging is good is fixed on the UUT that has fixing vibration frequency, during work, incident light from wideband light source 7 through 2 * 2 coupling mechanisms 9 and the calibration bragg grating 3 to suspension bragg grating 1, because the self character of fiber grating, the light that a part has certain wavelength can be reflected, and vibration when taking place in suspension bragg grating 1, catoptrical centre wavelength can change along with oscillation amplitude change,, demarcate with the difference of calibration bragg grating 3 reflected light centre wavelengths by measuring suspension bragg grating 1 after the reflected light of calibration bragg grating 3 and 2 * 2 coupling mechanisms 9 is detected by spectroanalysis instrument 8, show and output.When operating ambient temperature changes, reflected light centre wavelength between suspension bragg grating 1 and the calibration bragg grating 3 changes simultaneously, the difference of both change amounts is zero, so temperature variation can utilize this character to come the operating ambient temperature of survey sensor to the not influence of measurement of spectroanalysis instrument 8 on the contrary.
The modulation system of the present invention's structure shown in Figure 2 belongs to the modulation of light intensity type.The measuring principle of this structure is the reflected optical power P by sense cycle internal vibration amplitude maximum rating
1Reflected optical power P with equilibrium state
2, they are both ratio P
1/ P
2Become certain proportional relation with Oscillation Amplitude, simultaneously detection of reflected luminous power P
1With P
21/4 cycle of UUT vibration just in the time interval, the ratio by amplitude and time can obtain vibration velocity.Duty and wave length type modulation system are similar, and only terminal detects, shows and export with light power meter 10.When operating ambient temperature changes, though the reflected light centre wavelength of suspension bragg grating 1 changes, but because the luminous power that wideband light source 7 is launched on one section wavelength is more even, so the change of reflected light centre wavelength is little to catoptrical luminous power influence.
Among the present invention as sensing probe suspension bragg grating 1 both can be that an end is fixed, other end beam vibration freely, also can be the beam vibration that two ends are all fixed.
Claims (5)
1, a kind of optical fiber vibrative sensor based on fiber grating, it is characterized in that comprising suspension bragg grating (1), insulating concrete cylinder (2), calibration bragg grating (3), connector (4), connector (5), matching fluid (6), wideband light source (7), 2 * 2 coupling mechanisms (9) and spectroanalysis instrument (8), an interface of 2 * 2 coupling mechanisms (9) one ends links to each other with wideband light source (7), another interface links to each other with spectroanalysis instrument (8), two interfaces of the other end of 2 * 2 coupling mechanisms (9) connect matching fluid (6) and Transmission Fibers respectively, the threaded one end of the insulating concrete cylinder of hollow (2) connects connector (4), Transmission Fibers is passed connector (4) and is entered insulating concrete cylinder (2), and be fixed on the center of insulating concrete cylinder (2) by connector (5), the end of Transmission Fibers in insulating concrete cylinder (2) is carved with the suspension bragg grating (1) of the usefulness that is used to resonate, suspension bragg grating (1) is affixed with the intersection of connector (5), have in the connector (4) of internal thread with externally threaded connector (5) precession, with in the internal thread of externally threaded connector (4) precession insulating concrete cylinder (2) one ends, one section Transmission Fibers of connector (4) inflow point is carved with the calibration bragg grating (3) that is used to demarcate vibration balancing position reflected light centre wavelength.
2, the optical fiber vibrative sensor based on fiber grating of claim 1, the spectroanalysis instrument (8) that it is characterized in that an interface connection in described 2 * 2 coupling mechanisms (9) substitutes with light power meter (10), and the Transmission Fibers of connector (4) inflow point no longer is carved with calibration bragg grating (3).
3, claim 1 or 2 the optical fiber vibrative sensor based on fiber grating is characterized in that the length of described suspension bragg grating (1) is got 20-80mm, and diameter is got 0.1-0.8mm.
4, claim 1 or 2 the optical fiber vibrative sensor based on fiber grating is characterized in that described suspension bragg grating (1) is that an end is fixed, other end beam vibration freely, or are the beam vibration that two ends are all fixed.
5, the optical fiber vibrative sensor based on fiber grating of claim 2 is characterized in that described suspension bragg grating (1) is identical with the reflected light centre wavelength of calibration bragg grating (3).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410066814 CN1292238C (en) | 2004-09-29 | 2004-09-29 | Optical fiber vibrative sensor based on optical fiber raster |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410066814 CN1292238C (en) | 2004-09-29 | 2004-09-29 | Optical fiber vibrative sensor based on optical fiber raster |
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| CN1587946A CN1587946A (en) | 2005-03-02 |
| CN1292238C true CN1292238C (en) | 2006-12-27 |
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| CN 200410066814 Expired - Fee Related CN1292238C (en) | 2004-09-29 | 2004-09-29 | Optical fiber vibrative sensor based on optical fiber raster |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102944298A (en) * | 2012-11-06 | 2013-02-27 | 重庆大学 | End sensitive fiber bragg grating high-intensity focused ultrasound sensor and system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100587415C (en) * | 2007-04-11 | 2010-02-03 | 中国科学院半导体研究所 | Piston type optical fibre grating sonic device |
| CN102426198B (en) * | 2011-08-19 | 2014-05-07 | 北京航空航天大学 | Acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG) |
| CN102645237A (en) * | 2012-05-03 | 2012-08-22 | 浙江大学 | Method and device for manufacturing low-loss micro-nanometer fiber bragg grating sensor in chemical corrosion method |
| CN103217632A (en) * | 2013-02-27 | 2013-07-24 | 上海大学 | Point contact type optical fiber ultrasonic sensor |
| CN105277269A (en) * | 2014-07-22 | 2016-01-27 | 中国石油化工股份有限公司 | Phase shift fiber grating probe and manufacture method thereof |
| CN105628172A (en) * | 2015-11-10 | 2016-06-01 | 华北电力大学（保定） | Novel fiber grating vibration acceleration sensor |
| CN109520610A (en) * | 2018-12-27 | 2019-03-26 | 国网宁夏电力有限公司电力科学研究院 | A kind of adjustable optical fiber raster vibration sensor of frequency |
| CN111397723B (en) * | 2020-04-27 | 2022-06-28 | 山东省科学院激光研究所 | Three-component optical fiber laser micro-vibration sensor with combined structure and application thereof |
| CN113029482B (en) * | 2021-02-25 | 2022-07-26 | 江西师范大学 | Bolt tightness detection method and detection device |
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2004
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102944298A (en) * | 2012-11-06 | 2013-02-27 | 重庆大学 | End sensitive fiber bragg grating high-intensity focused ultrasound sensor and system |
| CN102944298B (en) * | 2012-11-06 | 2015-04-29 | 重庆大学 | End sensitive fiber bragg grating high-intensity focused ultrasound sensor and system |
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| CN1587946A (en) | 2005-03-02 |
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