CN220040253U - Optical fiber torsion sensor based on dumbbell-shaped structure - Google Patents
Optical fiber torsion sensor based on dumbbell-shaped structure Download PDFInfo
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- CN220040253U CN220040253U CN202320855063.XU CN202320855063U CN220040253U CN 220040253 U CN220040253 U CN 220040253U CN 202320855063 U CN202320855063 U CN 202320855063U CN 220040253 U CN220040253 U CN 220040253U
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 124
- 239000000835 fiber Substances 0.000 claims abstract description 73
- 238000005253 cladding Methods 0.000 claims abstract description 30
- 230000035945 sensitivity Effects 0.000 description 8
- 238000012544 monitoring process Methods 0.000 description 7
- 238000001514 detection method Methods 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 4
- 239000003292 glue Substances 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 238000000411 transmission spectrum Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 238000007526 fusion splicing Methods 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010291 electrical method Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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Abstract
The utility model discloses an optical fiber torsion sensor based on a dumbbell structure, which comprises an incident optical fiber, a non-circular symmetrical optical fiber and an emergent optical fiber; either end of the incident optical fiber is of a first spherical structure; the first spherical structure is connected with one end of the non-circular symmetrical optical fiber; any end of the emergent optical fiber is of a second spherical structure; the other end of the non-circular symmetrical optical fiber is connected with the second spherical structure, the non-circular symmetrical optical fiber comprises a second fiber core arranged in the center of the non-circular symmetrical optical fiber, a third fiber core and an outer second cladding, the third fiber core is a certain distance away from the center of the non-circular symmetrical optical fiber, and the two ends of the second fiber core and the third fiber core are not connected with the first spherical fiber core and the second spherical fiber core.
Description
Technical Field
The utility model relates to an optical fiber torsion sensor based on a dumbbell structure, and belongs to the field of optical fiber sensing.
Background
In recent years, with the continuous development of heavy industry, there is an increasing demand for performance monitoring such as torsional deformation of mechanical devices. Torsion is one of important mechanical parameters in building safety monitoring, stress states of the structure can be known in time through monitoring the torsion parameters, internal damage is found, and the analysis of health states of large-scale equipment or buildings (such as bridges, spacecrafts, civil engineering applications and the like) is facilitated, so that accident occurrence rate is greatly reduced, and personnel safety is guaranteed.
There are two types of conventional torsion sensors: one type is an electrical method based sensor; another type is a sensor based on electromagnetic phenomena. Both types of sensors are susceptible to factors such as temperature and noise, and have complex structures and are difficult to embed in a monitoring structure. The optical fiber torsion sensor can not only effectively overcome the problems, but also has the advantages of light weight, small volume, no electromagnetic interference, higher sensitivity and small axial strain interference, and can meet most of requirements. Currently, the optical fiber torsion sensor mainly comprises an optical fiber bragg grating type (FBG, fiber Bragg Grating), an optical fiber interference type, a multimode optical fiber winding type (such as an FBG, a Sagnac interferometer and a polarization maintaining optical fiber) and the like, and can adapt to various different requirements.
However, the existing optical fiber sensor has some problems, and most sensing schemes cannot realize high-precision torsion detection in a smaller wavelength detection range and simultaneously know the number of torsion turns; the sensor has complex manufacturing method and higher manufacturing cost.
Disclosure of Invention
The utility model aims to solve the technical problems and provides an optical fiber torsion sensor based on a dumbbell structure, which has the characteristics of higher torsion sensitivity and distinguishable rotation angle.
In order to solve the technical problems, the utility model adopts the following technical scheme:
an optical fiber torsion sensor based on a dumbbell structure comprises an incident optical fiber, a non-circular symmetrical optical fiber and an emergent optical fiber; the incident optical fiber and the emergent optical fiber are single-mode optical fibers and respectively comprise a first fiber core and a first cladding of an outer layer; the optical fiber comprises an incident optical fiber, a first spherical structure and a second spherical structure, wherein any end of the incident optical fiber is provided with the first spherical structure, the first spherical structure comprises a first spherical fiber core with a spherical inner part and a cladding coated on an outer layer, and the first spherical fiber core is connected with the first fiber core of the incident optical fiber; the optical fiber comprises an emergent optical fiber, wherein any end of the emergent optical fiber is provided with a second spherical structure, the second spherical structure comprises a second spherical fiber core with a spherical inner part and a cladding coated on an outer layer, and the second spherical fiber core is connected with a first fiber core of the emergent optical fiber;
the two ends of the non-circular symmetrical optical fiber are respectively connected with the first spherical structure and the second spherical structure, the non-circular symmetrical optical fiber comprises a second fiber core arranged at the center of the non-circular symmetrical optical fiber, a third fiber core which is a certain distance away from the center of the non-circular symmetrical optical fiber and an outer second cladding, and the two ends of the second fiber core and the third fiber core are not connected with the first spherical fiber core and the second spherical fiber core.
The technical scheme of the utility model is further improved as follows: the diameter of the second fiber core is 7.6 mu m, the diameter of the third fiber core is 36 mu m, and the center of the third fiber core is 30 mu m away from the center of the non-circular symmetrical optical fiber.
The technical scheme of the utility model is further improved as follows: the diameter of the second cladding layer was 125 μm.
The technical scheme of the utility model is further improved as follows: the diameter of the first core is 9 μm and the diameter of the first cladding is 125 μm.
The technical scheme of the utility model is further improved as follows: the diameters of the first spherical structure and the second spherical structure are 172-175 mu m; the diameters of the first spherical fiber core and the second spherical fiber core are 12-13 mu m.
By adopting the technical scheme, the utility model has the following technical progress:
according to the optical fiber torsion sensor based on the dumbbell structure, the dumbbell structure is utilized to realize large-scale light splitting, the interference effect is enhanced, and the non-circular symmetrical optical fiber breaks the circular symmetrical structure of the optical fiber by introducing the third fiber core with the center distance of 30 mu m from the cladding into the cladding, so that the refractive index of an optical fiber material changes to different degrees when different angles of torsion occur, the effective refractive index of a transmission mode changes, and torsion angle measurement can be realized by monitoring wavelength changes. The sensor has the advantages of novel and compact structure, high sensitivity and small axial strain interference, and can be widely applied to the field of modern industrial automation.
Drawings
FIG. 1 is a schematic diagram of the structure of the present utility model;
FIG. 2 is a plot of sensitivity and error bars for the present utility model:
wherein (a) is 0 to 12.56rad/m; (b) 0-12.56 rad/m; (c) 12.56-25.13 rad/m; (d) 12.56-25.13 rad/m; (e) 25.13-37.70 rad/m; (f) 25.13 to 37.70rad/m; (g) 37.70-50.27 rad/m; (h) 37.70 to 50.27rad/m below;
wherein, 1, an incident optical fiber, 2, a non-circular symmetrical optical fiber, 3, an emergent optical fiber, 4, a first spherical structure, 5, a second spherical structure, 6, a first cladding, 7, first core, 8, first spherical core, 9, second spherical core, 10, second core, 11, third core, 12, second cladding.
Detailed Description
The utility model is further illustrated by the following examples:
in order to make the objects, technical solutions and advantages of the present utility model more apparent, the present utility model will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
The application scenario described in the embodiment of the present utility model is for more clearly describing the technical solution of the embodiment of the present utility model, and does not constitute a limitation on the technical solution provided by the embodiment of the present utility model, and as a person of ordinary skill in the art can know that the technical solution provided by the embodiment of the present utility model is applicable to similar technical problems as the new application scenario appears.
The optical fiber torsion sensor has the advantages of light weight, small volume, no electromagnetic interference and higher sensitivity, and can meet most of requirements. Currently, the optical fiber torsion sensor mainly comprises an optical Fiber Bragg Grating (FBG), an optical fiber interference type optical fiber winding type optical fiber, such as an FBG, a Sagnac interferometer and a polarization maintaining optical fiber, and the like, and can adapt to various different requirements. However, the existing optical fiber sensor has some problems, and most sensing schemes cannot realize high-precision torsion detection in a smaller wavelength detection range and simultaneously know the number of torsion turns; the sensor has complex manufacturing method and higher manufacturing cost.
In order to solve the problems, the utility model provides an optical fiber torsion sensor based on a dumbbell structure. The dumbbell-shaped structure is utilized to realize large-scale light splitting, interference effect is enhanced, the third fiber core with the center distance of 30 mu m from the cladding is introduced into the cladding to destroy the circular symmetrical structure of the optical fiber, so that the refractive index of the optical fiber material is changed to different degrees when different angles of torsion occur, the effective refractive index of a transmission mode is changed, and torsion angle measurement can be realized by monitoring wavelength change. The experimental result shows that the sensor has the characteristics of higher torsion sensitivity and distinguishable rotation angle.
Example 1:
as shown in fig. 1, an optical fiber torsion sensor based on a dumbbell structure according to the present utility model includes:
an incident optical fiber 1, a non-circularly symmetric optical fiber 2 and an outgoing optical fiber 3; either end of the incident optical fiber is provided with a first spherical structure 4; the first spherical structure 4 is connected with one end of the non-circularly symmetric optical fiber 2; either end of the emergent optical fiber 3 is provided with a second spherical structure 5; the other end of the non-circularly symmetric optical fiber is connected with the second spherical structure 5.
The incident optical fiber 1 and the outgoing optical fiber 3 may be, but not limited to, single-mode optical fibers, where the incident optical fiber is used for receiving light emitted by a laser, and the outgoing optical fiber is used for transmitting the light processed by the sensor to a spectrometer.
The incident optical fiber 1 and the emergent optical fiber 3 of the embodiment adopt single-mode optical fibers, and are composed of a first fiber core 6 and a first cladding 7, wherein the first fiber core of the single-mode optical fibers is positioned in the center of the single-mode optical fibers, the diameter of the first fiber core of the single-mode optical fibers of the embodiment is 9 μm, and the diameter of the first cladding of the single-mode optical fibers is 125 μm.
Specifically, the first spherical structure 4 is obtained by discharging either end of the incident single-mode fiber through a fusion splicing device, and the fusion splicing device according to the embodiment of the utility model may be, but not limited to, an optical fiber fusion splicer (FITEL S178), removing a certain length of coating layer from the incident fiber portion and flattening the end face, placing the optical fiber portion in the optical fiber fusion splicer (FITELs 178) and aligning with an electrode rod, pushing 58.8 μm to the fiber-free side, and discharging to obtain the first spherical structure 4. And the structure of the core portion corresponding to the first spherical structure 4 is also changed due to the discharging operation, resulting in a core of spherical shape, i.e., the first spherical core 8.
Similarly, after the outgoing optical fiber 3 is discharged through the welding device, either end of the outgoing optical fiber is provided with a corresponding second spherical structure and a corresponding second spherical optical fiber 9. Specifically, the diameters of the first spherical structure and the second spherical structure are 172-175 μm; the first and second spherical cores 9 have a diameter of 12 to 13 μm.
The first spherical structure enables light to be transmitted to the spherical structure part through a single mode fiber, cladding modes with different effective refractive indexes are excited due to mismatching of mode fields, part of light is leaked to the spherical structure cladding, the rest of light continues to propagate in the spherical fiber core, the rest of light is input into the non-circularly symmetric optical fiber, and the circularly symmetric structure of the optical fiber is broken due to the fact that a third fiber core which is 30 mu m away from the center of the cladding is introduced into the cladding, so that the excited cladding modes and the modes excited by the fiber core have non-circularly symmetry, and torsion angle measurement can be achieved in the torsion process;
the second spherical structure enables energy in the non-circular symmetrical fiber cladding and the fiber core to be re-coupled into the fiber core of the emergent fiber for transmission, and subsequent observation is facilitated.
The non-circular symmetrical optical fiber consists of a second fiber core 10, a third fiber core 11 and a second cladding 12, wherein two ends of the second fiber core 10 and the third fiber core 11 are not connected with the first spherical fiber core 8 and the second spherical fiber core 9. The diameter of the second fiber core of the non-circular symmetrical optical fiber is 7.6 mu m, and the second fiber core of the non-circular symmetrical optical fiber is positioned at the center of the non-circular symmetrical optical fiber; the third fiber core diameter of the non-circular symmetrical optical fiber is 36 mu m, and the center of the third fiber core is offset from the center of the non-circular symmetrical optical fiber core by 30 mu m; the diameter of the second cladding of the non-circularly symmetric fiber was 125 μm.
Currently, most sensing schemes cannot achieve high-precision torsion detection in a small wavelength detection range while knowing the number of turns. The utility model provides an optical fiber torsion sensor based on a dumbbell structure. The third fiber core which is staggered with the center of the cladding by 30 mu m is introduced into the non-circular symmetrical optical fiber to destroy the circular symmetrical structure of the optical fiber, so that the refractive index of the optical fiber material can be changed to different degrees when the optical fiber is twisted at different angles, the effective refractive index of a transmission mode is changed, and the torsion angle measurement can be realized by monitoring the wavelength change.
The steps of performing torsion at different angles by the torsion sensor and obtaining ASE spectrum data are described as follows:
fixing an incident optical fiber of a sensor on one side of a Fix disk of a torsion device by using AB glue, and waiting for 30 minutes to thoroughly solidify the AB glue; straightening the sensor, fixing the emergent optical fiber on one side of a Rotating disk of the torsion device by using AB glue, and waiting for 30 minutes to thoroughly solidify the AB glue; maintaining the sensor level, connecting the OSA to the sensor's incident fiber, and connecting the ASE to the sensor's exit fiber; rotating one side of a Rotating disk of the torsion device, and recording ASE spectrum data once every 10 degrees; and (3) after the Rotating disk side of the torsion device is restored to the 0 degree scale, recording ASE spectrum data at intervals of-10 degrees.
Fitting the drift amount of the transmission spectrum, taking an interference peak near 1570nm for data fitting, and simultaneously, for detecting the stability of the sensor, carrying out 3 repeated measurements, wherein a fitting curve and an error bar obtained from the measurement results are shown in fig. 2. Wherein: (a) 0-12.56 rad/m; (b) 0-12.56 rad/m; (c) 12.56-25.13 rad/m; (d) 12.56-25.13 rad/m; (e) 25.13-37.70 rad/m; (f) 25.13 to 37.70rad/m; (g) 37.70-50.27 rad/m; (h) 37.70 to 50.27rad/m below.
Theoretical and experimental results show that when the sensor is subjected to torsion change of 0 to +/-16 pi rad/m, the transmission spectrum is subjected to blue shift when the torsion angle is 0 to +/-4 pi rad/m and +/-8 pi rad/m to +/-12 pi rad/m, and the transmission spectrum is subjected to red shift within the range of +/-4 pi rad/m to +/-8 pi rad/m and +/-12 pi rad/m to +/-16 pi rad/m, and the maximum sensitivity is 0.75996nm/rad/m. In addition, the influence of the axial strain on the sensor result is small, and the experimental result is not interfered. Therefore, the sensor has the advantages of novel and compact structure and high sensitivity, and can be widely applied to the field of modern industrial automation.
Claims (5)
1. An optical fiber torsion sensor based on dumbbell structure, its characterized in that: comprises an incident optical fiber (1), a non-circular symmetrical optical fiber (2) and an emergent optical fiber (3); the incident optical fiber (1) and the emergent optical fiber (3) are single-mode optical fibers and respectively comprise a first fiber core (7) and a first cladding (6) of an outer layer; the optical fiber comprises an incident optical fiber (1), wherein either end of the incident optical fiber (1) is provided with a first spherical structure (4), the first spherical structure (4) comprises a first spherical fiber core (8) with a spherical inner part and a cladding coated on an outer layer, and the first spherical fiber core (8) is connected with a first fiber core (7) of the incident optical fiber (1); a second spherical structure (5) is arranged at any end of the emergent optical fiber (3), the second spherical structure (5) comprises a second spherical fiber core (9) with a spherical inner part and a cladding coated on the outer layer, and the second spherical fiber core (9) is connected with the first fiber core (7) of the emergent optical fiber (3);
the two ends of the non-circular symmetrical optical fiber (2) are respectively connected with the first spherical structure (4) and the second spherical structure (5), the non-circular symmetrical optical fiber comprises a second fiber core (10) arranged in the center of the non-circular symmetrical optical fiber, a third fiber core (11) which is a certain distance away from the center of the non-circular symmetrical optical fiber and an outer second cladding (12), and the two ends of the second fiber core (10) and the third fiber core (11) are not connected with the first spherical fiber core (8) and the second spherical fiber core (9).
2. The dumbbell-based optical fiber torsion sensor according to claim 1, wherein: the diameter of the second fiber core (10) is 7.6 mu m, the diameter of the third fiber core (11) is 36 mu m, and the center of the third fiber core (11) is 30 mu m away from the center of the non-circular symmetrical optical fiber.
3. The dumbbell-based optical fiber torsion sensor according to claim 2, wherein: the diameter of the second cladding layer (12) is 125 μm.
4. The dumbbell-based optical fiber torsion sensor according to claim 1, wherein: the diameter of the first core (7) is 9 μm and the diameter of the first cladding (6) is 125 μm.
5. The dumbbell-based optical fiber torsion sensor according to claim 1, wherein: the diameters of the first spherical structure (4) and the second spherical structure (5) are 172-175 mu m; the diameters of the first spherical fiber core (8) and the second spherical fiber core (9) are 12-13 mu m.
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