CN108106711A - A kind of optical fiber vibration pickup and sensor-based system based on interference filter principle - Google Patents
A kind of optical fiber vibration pickup and sensor-based system based on interference filter principle Download PDFInfo
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- CN108106711A CN108106711A CN201711310043.XA CN201711310043A CN108106711A CN 108106711 A CN108106711 A CN 108106711A CN 201711310043 A CN201711310043 A CN 201711310043A CN 108106711 A CN108106711 A CN 108106711A
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 33
- 230000003287 optical effect Effects 0.000 claims abstract description 27
- 239000000835 fiber Substances 0.000 claims description 16
- 238000001914 filtration Methods 0.000 claims description 13
- 238000009434 installation Methods 0.000 claims description 4
- 230000005540 biological transmission Effects 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 10
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 abstract 3
- 238000005259 measurement Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 4
- 230000009977 dual effect Effects 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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Abstract
The present invention provides a kind of optical fiber vibration pickup based on interference filter principle, it is characterised in that：Including pedestal, cantilever beam, mass block, optical filter and collimator；It is fixed on positioned at cantilever beam one end of horizontal direction on pedestal, the cantilever beam other end is connected with mass block, and forming one can only be in the matter vibrating system of perpendicular internal vibration；Cantilever beam is equipped with centre bore, centre bore is equipped with optical filter, the upper and lower both sides of optical filter are respectively equipped with the input terminal and output terminal of light, collimator is equipped between optical filter and input terminal, between optical filter and output terminal, optical filter is coaxial with collimator, and collimator is fixed on by mounting bracket on pedestal；The input terminal and output terminal of the light are optical fiber.The present invention preferably solves the contradiction between sensitivity and Hz-KHz, substantially increases the sensing capabilities of low frequency vibration pickup.
Description
Technical Field
The invention belongs to the technical field of engineering vibration measurement and optical fiber sensing, and particularly relates to an optical fiber vibration pickup and a sensing system based on an interference filtering principle.
Background
In engineering vibration measurement, sensors for picking up vibration signals are mainly piezoelectric and electromagnetic vibration pickups. However, in some specific measurement occasions, such as high voltage, strong magnetic field, inflammable and explosive occasions, the application of the sensor is limited, so that the optical fiber vibration pickup should be allowed to generate, the existing optical fiber vibration pickup is divided from tuning parameters and has various sensors such as light intensity type, wavelength type, polarization type, phase type and the like, wherein the wavelength type optical fiber vibration pickup has the advantages of good long-term stability, high measurement precision and the like besides the characteristics of electromagnetic interference resistance and intrinsic safety, and is generally concerned in long-term monitoring of engineering vibration.
In low frequency vibration measurement, a common wavelength type fiber optic vibration pickup is based on a cantilever beam structure. However, the fiber grating vibration pickup with the structure has a problem in performance: i.e. sensitivity and operating band are often contradictory. When the frequency band is wider, the sensitivity is lower; if the sensitivity is to be improved, the bandwidth is affected, and this contradiction causes the application of the fiber grating low-frequency vibration pickup to be limited. For example, chinese patent No. ZL200520098628.6 discloses a "dual cantilever fiber grating vibration sensor", which uses dual cantilever beams and dual fiber gratings to better solve the problems of temperature influence and wavelength signal demodulation. But the sensitivity and the frequency response bandwidth of the sensor are adjusted by changing the structural parameters of the cantilever beam, and the adjusting range is very limited. On the premise of meeting the requirement of measurement accuracy, the frequency response bandwidth of the sensor is too narrow to meet the application requirement of engineering vibration measurement; in addition, chinese patent No. ZL201310749018.7 discloses "a fiber grating vibration sensor for liquid medium", which adopts an improved cantilever beam (L-beam) structure and a double grating design, thereby better solving the temperature compensation problem and significantly improving the detection sensitivity of the sensor. However, in order to improve the long-term durability of the fiber grating, the vibration amplitude must be reduced at the expense of frequency response.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the optical fiber vibration pickup and the sensing system based on the interference filtering principle are provided, and a wider low-frequency measuring range can be provided on the premise of ensuring the precision.
The technical scheme adopted by the invention for solving the technical problems is as follows: an optical fiber vibration pickup based on the interference filtering principle, characterized in that: the device comprises a base, a cantilever beam, a mass block, an optical filter and a collimator; wherein,
one end of the cantilever beam in the horizontal direction is fixed on the base, and the other end of the cantilever beam is connected with the mass block to form a mass-vibration system which can only vibrate in a vertical plane;
the optical filter is coaxial with the collimator, and the collimator is fixed on the base through a mounting bracket; the input end and the output end of the light are both optical fibers.
According to the above scheme, the base be the integral structure that 4 faces constitute, 4 faces be A face, B face, C face and D face respectively, wherein the installation bottom surface of optical fiber vibration pickup is regarded as to the D face, A face, B face and C face are 3 sides, A face be used for with cantilever beam one end fixed, the collimater pass through the installing support and be connected with B face and C face.
According to the scheme, the mounting bracket comprises a square frame; 2 connecting arms on the same straight line are arranged on the square frame, and the collimator is embedded in the connecting arms; the square frame is also provided with 2 mounting arms which are respectively connected with the surface B and the surface C; the cantilever beam and the mass block are penetrated in the square frame.
According to the scheme, when no vibration exists, the included angle between the 2 connecting arms and the vertical plane is set as an initial angle, and the mounting arms are connected with the surface B and the surface C and can be adjusted so as to adjust the initial angle.
An optical fiber vibration sensing system, characterized by: the fiber vibration pickup device comprises 1 broadband light source, 2 1 x n splitters, n fiber vibration pickups based on the interference filtering principle and 1 wavelength demodulator; the broadband light source is divided into n paths by one 1 xn branching unit, and the n paths of light are synthesized into one path of optical signal by the other 1 xn branching unit and transmitted to the wavelength demodulator after passing through the n optical fiber vibration pickups respectively; n optical filter transmission light wavelength lambda of optical fiber vibration pickup1,λ2...λnIs within a range of | λi-λi-1And | is more than 1nm (i is more than or equal to 2 and less than or equal to n) and is within the bandwidth range of the wavelength of the broadband light source.
The invention has the beneficial effects that: compared with a fiber grating vibration pickup, the low-frequency vibration pickup has higher sensitivity, because the sensitivity of the sensor is adjusted by mainly adjusting the initial angle of incident light instead of only adjusting the structural parameters of a cantilever beam, the contradiction between the sensitivity and the frequency response range is better solved, and the sensing performance of the low-frequency vibration pickup is greatly improved; compared with the fiber bragg grating, the filter is small in size and convenient to install, the size of the sensor is greatly reduced, and the structure of the sensor is simplified.
Drawings
Fig. 1 is a schematic structural diagram according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a base according to an embodiment of the invention.
Fig. 3 is a schematic structural diagram of a mounting bracket according to an embodiment of the invention.
FIG. 4 is a functional block diagram of an embodiment of the present invention.
In the figure: 1-mass block, 2-cantilever beam, 3-collimator, 4-optical filter, 5-input end, 6-output end, 7-base, 8-mounting bracket, 9-connecting arm and 10-mounting arm.
Detailed Description
The invention is further illustrated by the following specific examples and figures.
The invention provides an optical fiber vibration pickup based on interference filtering principle, as shown in fig. 1 to 3, comprising a base 7, a cantilever beam 2, a mass block 1, an optical filter 4 and a collimator 3; one end of a cantilever beam 2 positioned in the horizontal direction is fixed on a base 7, and the other end of the cantilever beam 2 is connected with a mass block 1 to form a mass-vibration system which can only vibrate in a vertical plane; the cantilever beam 2 is provided with a central hole, an optical filter 4 is arranged on the central hole, the upper side and the lower side of the optical filter 4 are respectively provided with an input end 5 and an output end 6 of light, collimators 3 are arranged between the optical filter 4 and the input end 5 and between the optical filter 4 and the output end 6, the optical filter 4 is coaxial with the collimators 3, and the collimators 3 are fixed on a base 7 through a mounting bracket 8; the light input end 5 and the light output end 6 are both optical fibers.
Further, base 7 be the integrated structure that 4 faces constitute, 4 faces be A face, B face, C face and D face respectively, wherein the D face is as the installation bottom surface of optical fiber vibration pickup, A face, B face and C face are 3 sides, A face be used for with 2 one end of cantilever beam fixed, collimator 3 pass through installing support 8 and be connected with B face and C face.
Still further, the mounting bracket 8 comprises a square frame; 2 connecting arms 9 on the same straight line are arranged on the square frame, and the collimator 3 is embedded in the connecting arms 9; the square frame is also provided with 2 mounting arms 10 which are respectively connected with the surface B and the surface C; the cantilever beam 2 and the mass block 1 are penetrated in the square frame.
When no vibration exists, the included angle between the 2 connecting arms 9 and the vertical plane is set as an initial angle, and the mounting arm 10 is connected with the surface B and the surface C and can be adjusted to cause the rotation of the mounting bracket 8 so as to adjust the initial angle. When light emitted from the broadband light source is incident on the filter 4 through the collimator 3, the wavelength of the transmitted light depends on the vibration state and the initial angle of the mass-vibration system. The initial angle, defined as the angle between the incident light and the vertical plane, determines the sensitivity coefficient of the fiber optic vibration pickup, and can be adjusted by rotating the mounting bracket.
The working principle of the optical fiber vibration pickup is as follows: the installation bottom surface of the optical fiber vibration pickup is installed on a measured structure, when the measured structure vibrates, the optical fiber vibration pickup installed on the structure also synchronously vibrates, the periodic vibration of the mass block 1 also causes the periodic change of the vertical deflection of the cantilever beam 2, at the moment, the included angle between the incident light of the collimator 3 and the surface of the optical filter 4 changes, the change quantity of the included angle is determined by the vibration amplitude and the frequency of the structure, the optical path of the incident light passing through the optical filter 4 actually changes, the wavelength of the light passing through the optical filter 4 changes correspondingly due to interference, and the change of the wavelength of the transmitted light has a definite relation with the vibration amplitude and the frequency of the structure, so that the vibration information of the structure can be obtained by collecting the wavelength change data of the transmitted light.
The invention also provides an optical fiber vibration sensing system, as shown in fig. 4, comprising 1 broadband light source, 2 1 xn splitters, n optical fiber vibration pickups based on the interference filtering principle and 1 wavelength demodulator; wherein, the light emitted by the broadband light source is divided into n paths by one of the 1 xn branching units, and the n paths are respectivelyAfter passing through n optical fiber vibration pickups, another 1 xn splitter synthesizes a path of optical signal and transmits the optical signal to a wavelength demodulator; in order to better demodulate the wavelength, n filters 4 of the fiber optic vibration pickup transmit the wavelength λ of light1,λ2...λnIs within a range of | λi-λi-1And | is more than 1nm (i is more than or equal to 2 and less than or equal to n) and is within the bandwidth range of the wavelength of the broadband light source, so that the matching of the optical filter 4 and the broadband light source is ensured. The sensing system adopts a pair of splitters to multiplex a plurality of optical fiber vibration pickups on one optical fiber, thereby realizing wavelength division multiplexing. The wavelength bandwidth of the light source and the wavelength bandwidth of the demodulator are fully utilized, the capacity of the sensing network is improved, and the manufacturing cost of the system is reduced.
The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.
Claims (5)
1. An optical fiber vibration pickup based on the interference filtering principle, characterized in that: the device comprises a base, a cantilever beam, a mass block, an optical filter and a collimator; wherein,
one end of the cantilever beam in the horizontal direction is fixed on the base, and the other end of the cantilever beam is connected with the mass block to form a mass-vibration system which can only vibrate in a vertical plane;
the optical filter is coaxial with the collimator, and the collimator is fixed on the base through a mounting bracket; the input end and the output end of the light are both optical fibers.
2. A fiber optic resonator based on the interference filtering principle according to claim 1, characterized in that: the base be the integrated structure that 4 faces constitute, 4 faces be A face, B face, C face and D face respectively, wherein the installation bottom surface of optical fiber vibration pickup is regarded as to D face, A face, B face and C face are 3 sides, A face be used for with cantilever beam one end fixed, the collimater pass through the installing support and be connected with B face and C face.
3. A fiber optic resonator based on the interference filtering principle according to claim 2, characterized in that: the mounting bracket comprises a square frame; 2 connecting arms on the same straight line are arranged on the square frame, and the collimator is embedded in the connecting arms; the square frame is also provided with 2 mounting arms which are respectively connected with the surface B and the surface C; the cantilever beam and the mass block are penetrated in the square frame.
4. A fiber optic resonator based on the interference filtering principle according to claim 3, characterized in that: and when no vibration exists, the included angle between the 2 connecting arms and the vertical plane is set as an initial angle, and the mounting arm is connected with the surface B and the surface C and can be adjusted so as to adjust the initial angle.
5. An optical fiber vibration sensing system, characterized by: the fiber-optic vibration pickup based on the interference filtering principle comprises 1 broadband light source, 2 1 x n splitters, n fiber-optic vibration pickups based on the interference filtering principle and 1 wavelength demodulator, wherein the fiber-optic vibration pickups are arranged on the broadband light source; the broadband light source is divided into n paths by one 1 xn branching unit, and the n paths of light are synthesized into one path of optical signal by the other 1 xn branching unit and transmitted to the wavelength demodulator after passing through the n optical fiber vibration pickups respectively; n optical filter transmission light wavelength of the optical fiber vibration pickupλ1,λ2...λnIs within a range of | λi-λi-1I is more than 1nm, i is more than or equal to 2 and less than or equal to n, and the i and the n are all within the bandwidth range of the wavelength of the broadband light source.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110940297A (en) * | 2019-12-05 | 2020-03-31 | 武汉理工大学 | Optical fiber tilt angle sensor and detection system thereof |
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