CN108106711B - optical fiber vibration pickup and sensing system based on interference filtering principle - Google Patents
optical fiber vibration pickup and sensing system based on interference filtering principle Download PDFInfo
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- CN108106711B CN108106711B CN201711310043.XA CN201711310043A CN108106711B CN 108106711 B CN108106711 B CN 108106711B CN 201711310043 A CN201711310043 A CN 201711310043A CN 108106711 B CN108106711 B CN 108106711B
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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
Abstract
The invention provides optical fiber vibration pickups based on interference filtering principle, which is characterized by comprising a base, a cantilever beam, a mass block, an optical filter and a collimator, wherein the cantilever beam positioned in the horizontal direction is fixed on the base, the other end of the cantilever beam is connected with the mass block to form mass-vibration systems which can only vibrate in a vertical plane, the cantilever beam is provided with a central hole, the optical filter is arranged in the central hole, the upper side and the lower side of the optical filter are respectively provided with an optical input end and an optical output end, the collimator is arranged between the optical filter and the input end and between the optical filter and the output end, the optical filter is coaxial with the collimator, the collimator is fixed on the base through a mounting bracket, and the optical input end and the optical output end are both optical fibers.
Description
Technical Field
The invention belongs to the technical field of engineering vibration measurement and optical fiber sensing, and particularly relates to optical fiber vibration pickups based on an interference filtering principle and a sensing system.
Background
However, in specific measurement occasions, such as high voltage, strong magnetic field, inflammable and explosive occasions, the application of the sensor is limited, the existing optical fiber vibration pickup is allowed to generate, the existing optical fiber vibration pickup is classified from tuning parameters, and various sensors such as light intensity type, wavelength type, polarization type, phase type and the like exist, 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.
For example, Chinese patent No. ZL200520098628.6 discloses a double-cantilever beam and double-fiber grating which better solves the problems of temperature influence and wavelength signal demodulation, but only changes the structural parameters of the cantilever beam to adjust the sensitivity and frequency response bandwidth of the sensor, and the adjustment range is very limited, so that the frequency response bandwidth of the sensor is too narrow to meet the application requirement of engineering vibration measurement on the premise of meeting the measurement accuracy requirement, and Chinese patent No. ZL201310749018.7 discloses a fiber grating vibration sensor for liquid media, which adopts an improved (L) beam structure, adopts a double-grating design, better solves the application requirement of engineering vibration measurement, and inevitably reduces the sensitivity of the fiber grating vibration sensor in order to improve the long-term vibration sensitivity and improve the durability of the fiber grating vibration sensor.
Disclosure of Invention
The invention aims to solve the technical problem that optical fiber vibration pickups and sensing systems 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 invention adopts the technical scheme that optical fiber vibration pickups based on the interference filter principle are characterized by comprising a base, a cantilever beam, a mass block, an optical filter and a collimator, wherein,
the end of cantilever beam in horizontal direction is fixed on the base, the end of cantilever beam is connected with the mass block, to form mass-vibration systems which can only vibrate in 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 scheme, the base is an -body structure formed by 4 surfaces, the 4 surfaces are respectively an A surface, a B surface, a C surface and a D surface, the D surface is used as the installation bottom surface of the optical fiber vibration pickup, the A surface, the B surface and the C surface are 3 side surfaces, the A surface is used for being fixed with the cantilever beam end, and the collimator is connected with the B surface and the C surface through the installation support.
According to the scheme, the mounting support comprises a square-shaped frame, 2 connecting arms which are arranged on the square-shaped frame and are on the same straight line of , the collimator is embedded in the connecting arms, 2 mounting arms are further arranged on the square-shaped frame and are respectively connected with the surface B and the surface C, and the cantilever beam and the mass block penetrate through the square-shaped 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.
optical fiber vibration sensing system is characterized by comprising 1 broadband light source, 2 1 xn splitters, n optical fiber vibration pickups based on interference filtering principle and 1 wavelength demodulator, wherein light emitted by the broadband light source is divided into n paths by 1 xn splitters, passes through the n optical fiber vibration pickups respectively, is synthesized into optical signals by another 1 xn splitters and is transmitted to the wavelength demodulator, and the optical filter of the n optical fiber vibration pickups transmits the optical wavelength lambda1,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 of an embodiment of the present invention.
FIG. 2 is a schematic structural diagram of a base according to an embodiment of the present invention.
Fig. 3 is a schematic view of a mounting bracket according to an embodiment of the present 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 in connection with the following examples and the accompanying drawings.
The invention provides optical fiber vibration pickups based on interference filtering principle, as shown in fig. 1 to fig. 3, comprising a base 7, a cantilever beam 2, a mass block 1, an optical filter 4 and a collimator 3, wherein the cantilever beam 2 end located in the horizontal direction is fixed on the base 7, the other end of the cantilever beam 2 is connected with the mass block 1 to form mass-vibration systems which can only vibrate in the vertical plane, the cantilever beam 2 is provided with a central hole, the central hole is provided with the optical filter 4, the upper and lower sides of the optical filter 4 are respectively provided with an optical input end 5 and an optical output end 6, the collimator 3 is arranged between the optical filter 4 and the input end 5 and between the optical filter 4 and the optical output end 6, the optical filter 4 is coaxial with the collimator 3, the collimator 3 is fixed on the base 7 through a mounting bracket 8, and the optical input end 5 and the optical.
, the base 7 is a body structure composed of 4 faces, the 4 faces are respectively a face, a face and a face D, wherein the face D is used as the installation bottom face of the optical fiber vibration pickup, the face A, the face B and the face C are 3 side faces, the face A is used for fixing the end of the cantilever beam 2 , and the collimator 3 is connected with the face B and the face C through the installation support 8.
And , wherein the mounting bracket 8 comprises a square frame, the square frame is provided with 2 connecting arms 9 on the same straight line , 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, and the cantilever beam 2 and the mass block 1 penetrate through 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 optical fiber vibration sensing systems, as shown in fig. 4, comprising 1 broadband light source, 2 1 xn splitters, n optical fiber vibration pickups based on interference filter principle and 1 wavelength demodulator, wherein the light emitted by the broadband light source passes through of the 1 xn splitters to be divided into n paths, passes through n optical fiber vibration pickups respectively, and then is synthesized into optical signals by another of the 1 xn splitters to be transmitted to the wavelength demodulator, and in order to better demodulate the wavelength, the optical filter 4 of n optical fiber vibration pickups transmits the optical wavelength λ1,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 is within the bandwidth range of the wavelength of the broadband light source, thereby ensuring the matching of the optical filter 4 and the broadband light source, the sensing system adopts pairs of splitters to multiplex a plurality of optical fiber vibration pickups on optical fibers,and wavelength division multiplexing is realized. 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 (2)
1, optical fiber vibration pickup based on interference filter principle, which is characterized in that it comprises base, cantilever beam, mass block, optical filter and collimator,
the end of cantilever beam in horizontal direction is fixed on the base, the end of cantilever beam is connected with the mass block, to form mass-vibration systems which can only vibrate in 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;
the base is an integrated structure formed by 4 surfaces, the 4 surfaces are respectively an A surface, a B surface, a C surface and a D surface, wherein the D surface is used as the mounting bottom surface of the optical fiber vibration pickup, the A surface, the B surface and the C surface are 3 side surfaces, the A surface is used for fixing with the end of the cantilever beam , and the collimator is connected with the B surface and the C surface through a mounting bracket;
the installation support comprises a square frame, wherein the square frame is provided with 2 connecting arms on the same line of , the collimator is embedded in the connecting arms, the square frame is also provided with 2 installation arms which are respectively connected with the surface B and the surface C, and the cantilever beam and the mass block penetrate through the square frame;
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.
2, optical fiber vibration sensing system, which is characterized in that it includes 1 broadband light source, 2 1 Xn branching units, n optical fiber vibration pickups based on interference filter principle and 1 wavelength demodulator, wherein, the light emitted from the broadband light source passes through branching units and is divided into n paths, after passing through n optical fiber vibration pickups, it is combined into optical signals by another branching units and transmitted to the wavelength demodulator, the optical filter of n optical fiber vibration pickups transmits the light wavelength lambda1,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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| CN106289166A (en) * | 2016-07-18 | 2017-01-04 | 武汉理工大学 | A kind of optical fiber obliquity sensor and wavelength-division multiplex method thereof |
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| DE102010019813A1 (en) * | 2010-05-06 | 2011-11-10 | Siemens Aktiengesellschaft | Fiber optic vibration sensor |
| JP6079739B2 (en) * | 2014-09-25 | 2017-02-15 | トヨタ自動車株式会社 | Measuring method of laser scanning speed |
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| CN101285845A (en) * | 2007-04-11 | 2008-10-15 | 中国科学院半导体研究所 | Cantilever beam type optical fibre grating accelerometer |
| CN101608944A (en) * | 2008-06-19 | 2009-12-23 | 上海前所光电科技有限公司 | A kind of optical fiber vibration sensing head and preparation method thereof |
| CN102080986A (en) * | 2009-11-30 | 2011-06-01 | 同方威视技术股份有限公司 | Fiber bragg grating vibration sensing component, fiber bragg grating vibration sensing device, vibration measuring system and method |
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