WO2019090786A1

WO2019090786A1 - Optical fiber fabry-perot sensor, and manufacturing method thereof

Info

Publication number: WO2019090786A1
Application number: PCT/CN2017/110735
Authority: WO
Inventors: 熊继军; 贾平岗; 房国成; 洪应平; 梁庭; 谭秋林; 刘文怡
Original assignee: 中北大学
Priority date: 2017-11-13
Filing date: 2017-11-13
Publication date: 2019-05-16

Abstract

An optical fiber Fabry-Perot sensor (1), and a manufacturing method thereof. The optical fiber Fabry-Perot sensor (1) comprises: a hollow tubular member (10) having a first tubular member (11), a cavity portion (12), and a second tubular member (13) sequentially arranged in an axial direction; a first optical fiber (20) provided within the first tubular member (11) in the axial direction, the first optical fiber (20) having a first light-transmitting end surface (21) provided within the cavity portion (12); and a second optical fiber (30) provided in the second tubular member (13) in the axial direction and having a second light-transmitting end surface (31) provided within the cavity portion (12), wherein the first light-transmitting end surface (30) and the second light-transmitting end surface (31) are spaced apart by a pre-determined distance and opposingly arranged, and the inner diameter of the cavity portion (12) is greater than the diameter of any one of the first tubular member (11) and the second tubular member (13).

Description

Optical fiber Fabry sensor and manufacturing method thereof

Technical field

The invention relates to a fiber optic Fabry sensor and a method of manufacturing the same.

Background technique

In recent years, with the rapid development in the fields of national defense, aerospace, energy, environment, electric power, and automobiles, higher requirements have been placed on the requirements of miniaturization, low energy consumption, and harsh environment. Fiber-optic sensors are receiving more and more attention because of their good stealth, high measurement accuracy and sensitivity, fast dynamic response speed, wide measurement range, intrinsic safety, and immunity to electromagnetic interference.

At present, commonly used single-point fiber-optic sensors mainly include fiber grating sensors, fiber Mach-Zehnder sensors, and fiber Fabry sensors. However, FBG sensors are sensitive to temperature and can cause large cross-interference in practical applications (especially in high temperature environments). The fiber Mach-Zehnder sensor has been studied more because of its simple structure, but its sensitivity is low and the volume is relatively large, which is limited in practical applications. Relatively speaking, fiber optic Fabry-Perot sensors are widely used due to their small size, simple structure and high sensitivity. Among them, fiber Fabry-Perot strain sensors, fiber Fabry-Perot force sensors and fiber Fabry-Perot pressure sensors are widely used in the fields of national defense safety, aerospace, and large-scale building health monitoring. However, the sensitivity of existing fiber Fabry-Perot sensors is still not ideal, and there is much room for improvement.

Summary of the invention

The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to provide an optical fiber Fabry sensor which improves measurement sensitivity and a method of manufacturing the same.

To this end, a first aspect of the present invention provides a fiber optic Fabry-Perot sensor, comprising: a hollow tube body having a first tube body, a cavity portion, and a second tube body sequentially arranged along an axial direction; An optical fiber disposed in the first tube body along the axial direction, the first optical fiber having a first light guiding end surface disposed in the cavity portion; and a second optical fiber, Provided in the second tube body along the axial direction, the second optical fiber has a second light guiding end surface disposed in the cavity portion, the first light guiding end surface and the second light guiding layer The end faces are oppositely disposed with a predetermined distance, and an inner diameter of the cavity portion is larger than an inner diameter of any one of the first pipe body and the second pipe body.

In a first aspect of the invention, in the hollow tube body, the first light guiding end surface of the first optical fiber and the second light guiding end surface of the second optical fiber are disposed in the cavity portion and are oppositely disposed with a predetermined distance therebetween, Therefore, when measuring with the fiber optic Fabry-Perot sensor of the present invention, external mechanical parameters (stress, tension, pressure, etc.) can be transmitted through the thin wall of the cavity portion, and the end face of the first optical fiber and the second optical fiber can be passed. The change of the length of the Faber cavity formed by the end face effectively reflects the change of the corresponding mechanical parameter. Therefore, the fiber optic Fabry-Perot sensor of the present invention can effectively improve the measurement sensitivity of the target mechanical parameter.

A second aspect of the present invention provides a fiber optic Fabry-Perot sensor comprising: a hollow tube body having a first tube body, a cavity portion, and a second tube body sequentially arranged along an axial direction; a first optical fiber a first light guiding end surface that is in contact with an end of the first tube body; and a second optical fiber having a second light guiding end surface that is in contact with an end of the second tube body, the first The light guiding end surface and the second light guiding end surface are oppositely disposed across the hollow tube body, and the inner diameter of the cavity portion is larger than any one of the first tube body and the second tube body The inner diameter of the body.

In the second aspect of the present invention, the first light guiding end surface of the first optical fiber and the second light guiding end surface of the second optical fiber are respectively disposed at both ends of the hollow tubular body, and therefore, the optical fiber Fabry-Perot sensor using the present invention When measuring, the external mechanical parameters (stress, tension, pressure, etc.) can be transmitted through the thin wall of the cavity, and the length of the Faber cavity formed by the end face of the first fiber and the end face of the second fiber is changed. In order to effectively reflect the change of the corresponding mechanical parameters, the optical fiber Fabry-Perot sensor of the present invention can effectively improve the measurement sensitivity of the target mechanical parameters.

Further, in the optical fiber Fabry sensor according to the first aspect or the second aspect of the invention, the first optical fiber may be welded to the first tubular body, and the second optical fiber may be welded to the second tubular body. In this case, it is possible to effectively form a closed cavity in the cavity portion between the first pipe body and the second pipe body, thereby improving the measurement sensitivity of the absolute pressure.

Further, in the optical fiber Fabry sensor according to the first or second aspect of the present invention, the first optical fiber and the second optical fiber are single mode fiber, multimode fiber, and polarization maintaining fiber. Or photonic crystal fiber. In this case, even if the first optical fiber and the second optical fiber are single mode fibers, multimode fibers, polarization maintaining fibers or photonic crystal fibers, sensitivity can be ensured.

Further, in the optical fiber Fabry sensor according to the first or second aspect of the invention, the first tube body, the cavity portion, and the second tube body are continuously formed, and the first The central axis of symmetry of the tubular body coincides with the central axis of symmetry of the second tubular body. In this case, since the first tube body, the cavity portion, and the second tube body are continuously formed, the first tube body, the cavity portion, and the second tube body can form a more confined space, thereby being able to improve Sensitivity.

Further, in the optical fiber Fabry sensor according to the first or second aspect of the present invention, the first light guiding end surface of the first optical fiber is perpendicular to the axial direction, and the second optical fiber is The second light guiding end surface is perpendicular to the axial direction.

Further, in the optical fiber Fabry sensor according to the first or second aspect of the present invention, the hollow tubular body has a center symmetry line, and the cavity portion is formed to be rotationally symmetrical about the central symmetry line structure. In this case, since the cavity portion is a rotationally symmetrical structure around the center symmetry line, the cavity portion can uniformly induce a change in the mechanical parameter, whereby the sensitivity of the fiber optic Fabry sensor can be further improved.

Further, in the optical fiber Fabry sensor according to the first or second aspect of the present invention, in the hollow tubular body, two are disposed between the first tubular body and the second tubular body More than one of the cavity portions. Thereby, the sensitivity of the fiber Fabry sensor can be further improved.

Further, in the optical fiber Fabry sensor according to the first or second aspect of the present invention, the first optical fiber and the hollow tubular body are formed with a first fusion joint, the second optical fiber and the middle The empty tubular body is formed with a second weld in the hollow tubular body between the first weld and the second weld.

Further, in the optical fiber Fabry sensor according to the first or second aspect of the invention, the first tube body, the cavity portion, and the second tube body are continuously formed, and the first The tubular body coincides with a central symmetry axis of the second tubular body. Preferably, the first tube body, the cavity portion and the second tube body are integrally formed. In this case, the sealing property of the hollow tubular body can be improved, which is advantageous in improving sensitivity.

Further, the optical fiber Fabry sensor according to the first aspect or the second aspect of the present invention The hollow tube body is a quartz glass tube, a high temperature resistant glass tube, a hollow fiber or a photonic crystal fiber. In this case, the high temperature resistance of the hollow tubular body and the process suitability of the hollow tubular body can be improved.

A third aspect of the invention provides a method of manufacturing a fiber optic Fabry sensor, comprising: preparing a hollow tube body, and performing wall thickness of the hollow tube body at a predetermined portion of the hollow tube body Thinning; filling the hollow tubular body with a heat-expandable substance to seal both ends of the hollow tubular body; heating the hollow tubular body to thermally expand the predetermined portion to form a cavity portion, Thereby forming a hollow tube body including the first tube body, the cavity portion and the second tube body arranged in sequence; fixing the first optical fiber to the first tube body, and fixing the second fiber to the first tube a second tube body, and the first light guiding end surface of the first optical fiber and the second light guiding end surface of the second optical fiber are disposed in the cavity portion and separated by a predetermined distance.

In the third aspect of the invention, the wall thickness is reduced by thinning at a predetermined portion of the hollow tubular body, and therefore, when the hollow tubular body is filled with the heat-expandable substance and heated, the pre-preparation The hollow tube body of the portion is expanded to form a cavity portion, and then the first optical fiber and the second optical fiber are welded to the hollow tube body, and the light guiding end surface of the first optical fiber is disposed apart from the light guiding end surface of the second optical fiber. Thereby, a fiber optic sensor having improved sensitivity can be formed.

A fourth aspect of the present invention provides a method of manufacturing a fiber optic Fabry-Perot sensor, comprising: preparing a hollow tube body, and thinning a wall thickness at a predetermined portion of the hollow tube body; Filling the hollow tubular body with a heat-expandable substance to seal both ends of the hollow tubular body; heating the hollow tubular body to thermally expand the predetermined portion to form a cavity portion, thereby forming the inclusion a first tube body, the cavity portion and a hollow tube body of the second tube body arranged in sequence; fixing an end surface of the first optical fiber to an end portion of the first tube body, and fixing an end surface of the second fiber to the end surface An end of the second tube body, and an end surface of the first optical fiber is disposed opposite to an end surface of the second optical fiber.

In the fourth aspect of the invention, the wall thickness is reduced by thinning at a predetermined portion of the hollow pipe body, and therefore, when the hollow pipe body is filled with the heat-expandable substance and heated, the pre-heating The hollow tube body of the portion is expanded to form a cavity portion, and then the first optical fiber and the second optical fiber are welded to the hollow tube body, and the light guiding end surface of the first optical fiber is separated from the light guiding end surface of the second optical fiber. The hollow tubes are opposed to each other, whereby a fiber optic sensor having improved sensitivity can be formed.

In the method of manufacturing the optical fiber Fabry sensor according to the third or fourth aspect of the present invention, the thermally expandable material may be air, an inert gas or an easily vaporizable substance. Thereby, the cavity portion can be easily produced by heating.

In the method of manufacturing a fiber optic Fabry-Perot sensor according to the third or fourth aspect of the present invention, the thinning is achieved by a processing method of etching, laser, plasma or sand blasting. In this case, the thinning of the hollow tubular body can be easily achieved.

In the method of manufacturing the optical fiber Fabry sensor according to the third or fourth aspect of the present invention, the thinning step includes: patterning an outer wall of the predetermined portion of the hollow tubular body, Forming an etching window at the predetermined portion; and etching the patterned hollow tube body to form a groove structure at the predetermined portion, so that the wall thickness of the predetermined portion is smaller than The wall thickness around the preset portion. In this case, the thinning of the hollow tubular body is achieved by an etching process, whereby the cavity portion can be conveniently prepared.

In the method of manufacturing a fiber optic Fabry-Perot sensor according to the third or fourth aspect of the present invention, the step of patterning comprises: applying a protective layer on an outer wall of the hollow tube; The hollow tubular body behind the layer is rotated around the central axis of the hollow tubular body and mask etched; and the protective layer is developed to remove the protective layer of the predetermined portion. In this case, the selection of the preset portion can be easily realized by the etching process, thereby improving the applicability of the fiber optic Fabry sensor preparation.

Further, in the method of manufacturing a fiber optic Fabry-Perot sensor according to the third or fourth aspect of the present invention, the hollow tube body is a quartz glass tube, a high temperature resistant glass tube, a hollow fiber or a photonic crystal fiber. In this case, the high temperature resistance of the hollow tubular body and the process suitability of the hollow tubular body can be improved.

A fifth aspect of the present invention provides a method of manufacturing a fiber optic Fabry sensor, comprising: preparing a hollow tube body, inserting and closing a first fiber to one end of the hollow tube body; and the hollow tube body The other end is connected to the high-voltage source; discharging the hollow tube body to thermally expand the predetermined portion to form a cavity portion, thereby forming a first tube body, the cavity portion and the second portion, which are sequentially arranged a hollow tubular body of the tubular body; inserting and fixing the second optical fiber to the second tubular body, and disposing the first light guiding end surface of the first optical fiber and the second light guiding end surface of the second optical fiber The cavity portion is within a predetermined distance.

In a fifth aspect of the invention, a hollow tubular body having a first tubular body, a cavity portion, and a second tubular body is formed by performing discharge at a predetermined portion of the hollow tubular body, and The end face of one of the optical fibers is disposed at a predetermined distance from the end face of the second optical fiber in the cavity portion, whereby an optical fiber Fabry sensor having improved sensitivity can be formed.

A sixth aspect of the present invention provides a method of manufacturing a fiber optic Fabry-Perot sensor, comprising: preparing a hollow tube body, fixing an end surface of the first optical fiber to one end of the hollow tube body and closing the middle One end of the hollow tube body; connecting the other end of the hollow tube body to a high-pressure source; discharging the hollow tube body to thermally expand the predetermined portion to form a cavity portion, thereby forming a step comprising a hollow body of the first tube body, the cavity portion and the second tube body; fixing an end surface of the second optical fiber to the second tube body and closing the second tube body.

In the fifth aspect of the invention, the hollow tube having the first tube body, the cavity portion, and the second tube body is formed by performing discharge at a predetermined portion of the hollow tube body, and the first fiber is made The end face is provided apart from the end face of the second optical fiber by the hollow pipe body, whereby an optical fiber Fabry sensor having improved sensitivity can be formed.

Further, in the method of manufacturing an optical fiber Fabry sensor according to the fifth or sixth aspect of the present invention, in the discharging the hollow tubular body, the hollow tubular body is disposed at a plurality of predetermined portions. The discharge is performed to form a plurality of cavity portions. Thereby, the measurement sensitivity can be further improved.

According to the present invention, it is possible to provide a fiber optic sensor that improves sensitivity and a method of manufacturing the same.

DRAWINGS

FIG. 1 is a schematic perspective view showing a fiber optic sensor of a first embodiment of the present invention.

FIG. 2 is a schematic perspective view showing another configuration of the optical fiber sensor according to the first embodiment of the present invention.

3 is a schematic perspective view showing a hollow tubular body of the optical fiber sensor sensor according to the first embodiment of the present invention.

4 is a schematic view showing a section of the hollow tubular body shown in FIG. 3 along the line L-L.

FIG. 5 is a schematic perspective structural view showing a modification of the optical fiber sensor according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing a method of manufacturing the optical fiber sensor according to the first embodiment of the present invention.

7a to 7e are schematic views showing the hollow tubular body of the optical fiber Fabry-Perot sensor shown in Fig. 6, wherein Fig. 7a is a perspective view showing the hollow tubular body; Fig. 7b is a view showing the coating 3D is a schematic view showing a hollow tube covered with a protective layer; FIG. 7c is a schematic perspective view showing the hollow tube covered with a plastic film; FIG. 7d is a perspective view showing the hollow tube after removing the protective layer; 7e is a schematic perspective view showing the prepared hollow tube body.

FIG. 8 is a flowchart showing another manufacturing method of the optical fiber sensor according to the first embodiment of the present invention.

9a to 9e are schematic views showing the hollow tubular body of the optical fiber Fabry-Perot sensor shown in Fig. 8, wherein Fig. 9a is a perspective view showing the hollow tubular body; Fig. 9b is a view showing A schematic view of the first optical fiber fixing and enclosing the hollow tubular body; FIG. 9c is a schematic cross-sectional view taken along line BB shown in FIG. 9b; and FIG. 9d is a view showing the hollow tubular body shown in FIG. 9c. A schematic view of the discharge; Figure 9e is a perspective view showing the prepared hollow tube body.

FIG. 10 is a schematic perspective view showing a fiber optic sensor according to a second embodiment of the present invention.

11a to 11e are schematic views showing the manufacture of the fiber optic sensor of FIG. 10, wherein FIG. 11a is a perspective view showing the hollow tube; FIG. 11b is a view showing the first fiber fixed and closed. FIG. 11c is a schematic cross-sectional view taken along line CC of FIG. 11b; FIG. 11d is a perspective view showing discharge of the hollow tube shown in FIG. 11c; FIG. 11e is a schematic view A stereo schematic of the prepared hollow tube body is shown.

Main symbol description:

1,1A...Fiber Faber sensor, 10... hollow tube, 11... tube (first tube), 12...cavity, 13... tube (second tube), 20... fiber (first Optical fiber), 21... inner end face (first end face), 22... outer end face, 30... fiber (second fiber), 31... inner end face (second end face), 32... outer end face.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals, and the description thereof will not be repeated. In addition, the drawings are only schematic diagrams, the ratio of the dimensions of the components to each other, the shape of the components, etc. Can be different from the actual one.

[First Embodiment]

FIG. 1 is a schematic perspective view showing a fiber optic sensor of the present embodiment. FIG. 2 is another schematic perspective view showing the optical fiber sensor of the present embodiment. In FIG. 1 and FIG. 2, for convenience of illustration, only a part of the optical fiber is shown. In practical applications, the length of the optical fiber can be determined according to actual conditions, the same below.

As shown in FIGS. 1 and 2, the optical fiber Fabry sensor 1 according to the present embodiment may include a hollow tubular body 10 and first optical fibers 20 and second optical fibers 30 disposed on both sides of the hollow tubular body 10. That is, the first optical fiber 20 and the second optical fiber 30 are respectively inserted into the hollow tubular body 10 from both sides of the hollow tubular body 10 and mounted (fixed) to the hollow tubular body 10 (see FIG. 4 described later). In some examples, the first optical fiber 20 and the second optical fiber 30 may respectively close the hollow tubular body 10 from both sides, thereby forming a sealed space within the hollow tubular body 10.

In the present embodiment, as shown in FIG. 1, the hollow tubular body 10 may have a first tubular body 11, a cavity portion 12, and a second tubular body 13 which are sequentially arranged along the axial direction thereof. That is, the cavity portion 12 is disposed between the first pipe body 11 and the second pipe body 13, and the first pipe body 11, the cavity portion 12, and the second pipe body 13 are sequentially connected.

In addition, the hollow pipe body 10 described herein is not limited to the case of a pipe body which is completely constant in inner diameter. For example, as described below, a portion of the hollow pipe body at a predetermined portion may be formed by expansion, which is formed by expansion. The shape of the expanded portion may be more inclined to a spherical shape or an irregular shape.

3 is a schematic perspective view showing a hollow tubular body of the optical fiber sensor of the present embodiment. 4 is a schematic view showing a section of the hollow tubular body shown in FIG. 3 along the line L-L. In Fig. 4, a perspective view of an optical fiber (including a first optical fiber 20 and a second optical fiber 30) is also shown.

In the present embodiment, the first optical fiber 20 may be disposed in the first pipe body 11 along the axial direction, and the second optical fiber 30 may be disposed in the second pipe body 13 along the axial direction. As shown in FIG. 1, the first optical fiber 20 has an inner end surface (i.e., a first light guiding end surface) 21 disposed in the cavity portion 12 and an outer end surface 22 away from the cavity portion 12 (see Fig. 4). The second optical fiber 30 has an inner end surface (second light guiding end surface) 31 disposed in the cavity portion 12 and an outer end surface 32 away from the cavity portion 12 (see FIG. 4).

Here, the outer end surface 22 of the first optical fiber 20 and the outer end surface 32 of the second optical fiber 30 are shown only for the sake of illustration. In fact, in the present embodiment, one end of the first optical fiber 20 including the outer end surface 22, and the second optical fiber The end 30 including the outer end face 32 may be separately connected to an external device such as an optical signal processing device (e.g., a spectrometer (not shown)), thereby enabling detection and presentation of optical signals captured by the first optical fiber 20 and the second optical fiber 30. (for example, via the display). In addition, in some examples, the optical signal processing device may also be integrated with the fiber optic Fabry sensor 1, whereby the data of the fiber Fabry sensor 1 can be known in real time, for example by reading the optical signal processing device.

In the present embodiment, the first light guiding end surface 21 may be opposite to the second light guiding end surface 31 by a predetermined distance D (see FIG. 4). Since the optical signal passes through the first light guiding end surface 21 of the first optical fiber 20 and the second light guiding end surface 31 of the second optical fiber 30, and correspondingly forms transmitted light, reflected light, and interference light, the first optical fiber 20 is disposed apart from each other. The first light guiding end surface 21 and the second light guiding end surface 31 of the second optical fiber 30 can form a Faber cavity. When external environmental strain occurs, the optical fibers (the first optical fiber 20 and the second optical fiber 30) located on both sides of the cavity portion 12 are subjected to, for example, tensile or compressive forces, causing the shape of the cavity portion 12 to be changed, by the first optical fiber 20. The distance D between the two inner end faces of the Faber cavity formed by the second optical fiber 30 (the first light guiding end face 21 and the second light guiding end face 31) is changed, thereby changing the interference spectrum, and by demodulating the interference spectrum, This makes it possible to measure the strain of the external environment.

Further, in some examples, the first optical fiber 20 can serve as an optical fiber for inputting optical signals, and the second optical fiber 30 can serve as an optical fiber that receives optical signals. However, the embodiment is not limited thereto. For example, the second optical fiber 30 may serve as an optical fiber that inputs an optical signal, and the first optical fiber 20 serves as an optical fiber that receives an optical signal.

In the present embodiment, the predetermined distance D between the first light guiding end surface 21 and the second light guiding end surface 31 is not particularly limited. In some examples, the preset distance D may be 5 μm to 100 μm (micrometers), preferably 5 μm to 20 μm. In this case, it is possible to more accurately detect the change in the interference spectrum formed by the Faber cavity. In some examples, the preset distance D may be 5 μm, 10 μm, 20 μm, 50 μm, 80 μm, or 100 μm.

In addition, in some examples, the wall thickness of the cavity portion 12 may be smaller than the wall thickness of any one of the first tube body 11 near the cavity portion 12 and the second tube body 13 near the cavity portion 12 (see Figure 4). In addition, the inner diameter of the cavity portion 12 may be larger than the inner diameter of any one of the first pipe body 11 and the second pipe body 13. In this case, the cavity portion 12 can be secured. The wall thickness is smaller than the wall thickness of the first pipe body 11 or the second pipe body 13, whereby the cavity portion 12 can sensitively sense changes in externally measured mechanical parameters when subjected to an external force, thereby improving sensitivity (or measurement sensitivity). ). In the present embodiment, the measured mechanical parameters may include, for example, tensile, compressive, bending, torsional, impact, alternating stress, and the like.

Further, in the present embodiment, the wall thickness of the cavity portion 12 may be 1 μm to 10 μm. Preferably, the wall portion has a wall thickness of from 2 μm to 8 μm. In this case, the sensitivity of the fiber Fabry sensor 1 can be improved. In some examples, the wall thickness of the cavity portion 12 may be 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, or 8 μm, 10 μm.

Further, in the present embodiment, the wall thickness of the cavity portion 12 does not have to be uniform, for example, the wall thickness of the center portion of the cavity portion 12 is the thinnest, and the wall thickness of the first pipe body 11 or the third pipe body 13 is closer to the wall thickness. Gradually thicker. In addition, the unevenness of the wall thickness of the cavity portion 12 may be caused during the thermal expansion process, and the heat or uneven force of the cavity portion 12 may cause a change in the wall thickness during the thermal expansion.

As described above, in the present embodiment, in the hollow tube body 10, the first light guiding end surface 21 of the first optical fiber 20 and the second light guiding end surface 31 of the second optical fiber 30 are disposed in the hollow tube body 10 The chambers 12 are disposed opposite each other with a predetermined distance D apart. Therefore, in the measurement of the mechanical parameters such as the stress measurement by the optical fiber Fabry sensor 1 according to the present embodiment, the length of the Fabry cavity formed by the first optical fiber 20 and the second optical fiber 30 (equal to the preset distance D) Since the change is made to effectively acquire the corresponding change in the mechanical parameters, the optical fiber sensor 1 according to the present embodiment can effectively improve the sensitivity.

Further, as described above, the wall thickness of the cavity portion 12 may be smaller than the wall thickness of the first pipe body 11 close to the cavity portion 12 and the wall thickness of the second pipe body 13 close to the cavity portion 12, and can pass Since the thin wall of the cavity portion 12 transmits a change in the external measured mechanical parameter, the optical fiber sensor 1 according to the present embodiment can further improve the sensitivity.

In the present embodiment, the hollow tubular body 10 is preferably a quartz glass tube. In this case, since the hollow tubular body 10 employs a quartz structure, it is possible to improve the high temperature resistance of the hollow tubular body and improve the process suitability of the hollow tubular body. As we all know, the main component of quartz glass tube is silicon dioxide. Silica is a commonly used material in microelectronics or MEMS technology. Therefore, using quartz glass tube as the main processing material can not only improve the high temperature resistance of hollow tube. It also improves the process suitability of the hollow tube. Further, the fiber Fabry sensor 1 made of a quartz glass tube can also have a lower temperature coefficient.

Additionally, in some examples, the hollow tubular body 10 can also be a high temperature resistant glass tube, a hollow fiber, a photonic crystal fiber, or the like.

In addition, in the present embodiment, the first light guiding end surface (inner end surface) 21 of the first optical fiber 20 and the second light guiding end surface (inner end surface) 31 of the second optical fiber 30 may be vertically flattened planes. That is, the first light guiding end surface 21 of the first optical fiber 20 and the second light guiding end surface 31 of the second optical fiber 30 are parallel to each other.

In addition, the first light guiding end surface 21 of the first optical fiber 20 and the second light guiding end surface 31 of the second optical fiber 30 can be adjusted by optical coating to improve the optical characteristics of the light guiding end surface of the optical fiber. In some examples, on the surface of the first light guiding end surface 21 and the surface of the second light guiding end surface 31, yttrium fluoride, ytterbium fluoride, lanthanum, zinc sulfide, magnesium fluoride, titanium oxide, zirconium oxide, or the like may be formed. The optical coating can be selected according to the actual application.

In the hollow tube body 10, for example, when incident light from a laser device propagates to the first light guiding end surface (inner end surface) 21 of the first optical fiber 20, part of the light is reflected back to the first optical fiber 20, and part of the light is transmitted through The light guiding end face 21 of the optical fiber 20 reaches the second light guiding end face (inner end face) 31 of the second optical fiber 30, at which time a part of the light is reflected and a part of the light is coupled into the second optical fiber 30. At this time, the Fabry cavity between the first light guiding end surface 21 of the first optical fiber 20 and the second light guiding end surface 31 of the second optical fiber 30 interferes. When the external environment strain occurs, the first optical fiber 20 on the side of the first pipe body 11 and the second optical fiber 30 on the side of the second pipe body 13 are subjected to, for example, a pulling force or a pressing force, so that the shape of the cavity body 12 changes. The distance between the first light guiding end face 21 of the optical fiber 20 and the second light guiding end face 31 of the second optical fiber 30 is changed, thereby changing the interference spectrum, and by demodulating the interference spectrum, it is possible to measure the external environmental strain amount.

In the present embodiment, the outer diameter of the first optical fiber 20 may be adapted to the inner diameter of the first tubular body 11 of the hollow tubular body 10, and the outer diameter of the second optical fiber 30 may be the first tubular body of the hollow tubular body 10. The inner diameter of 13 is adapted. In this case, the first optical fiber 20 and the second optical fiber 30 can be adaptively mounted in both sides of the hollow tubular body 10, respectively. That is, the first optical fiber 20 is adaptively mounted in the first tubular body 11, and the second optical fiber 30 is adaptively mounted in the second tubular body 13.

In some examples, in the fiber optic Fabry-Perot sensor 1, the first optical fiber 20 can be inserted into the first tubular body 11 and enclose the first tubular body 11, and the second optical fiber 30 can be inserted into the second tubular body 13 and enclose the second tubular body Body 13. In this case, a sealed space can be formed in the hollow pipe body 10, whereby the measurement sensitivity of, for example, absolute pressure can be improved.

Further, in the present embodiment, the first pipe body 11, the cavity portion 12, and the second pipe body 13 may be continuously formed. In other words, the first tubular body 11, the cavity portion 12 and the second tubular body 13 can form a continuous connecting surface without gaps between them. In this case, since the first tube body 11, the cavity portion 12, and the second tube body 13 are continuously formed, the first tube body 11, the cavity portion 12, and the second tube body 13 can be formed to be more closed. Space, thereby making it possible to increase the sensitivity of the measurement.

In addition, the central axis of symmetry of the first pipe body 11 may coincide with the central axis of symmetry of the second pipe body 13. In this case, the first optical fiber 20 mounted on the first pipe body 11 and the second optical fiber 30 mounted on the second pipe body 13 can be easily aligned, which makes it easier to measure the measured mechanical parameters.

Further, in the present embodiment, the first optical fiber 20 may be welded to the first tubular body 11, and the second optical fiber 30 may be welded to the second tubular body 13. In this case, the first pipe body 11 and the second pipe body 13 can be firmly fixed to both sides of the hollow pipe body 10, respectively.

In the present embodiment, the manner in which the first optical fiber 20 is welded to the first tubular body 11 and the manner in which the second optical fiber 30 is welded to the first tubular body 13 are not particularly limited. In some examples, the first optical fiber 20 may pass through the laser. The welding method is welded and fixed in the first pipe body 11, and the second fiber 30 can also be welded and fixed in the second pipe body 13 by a laser welding method. For the case where the first tube body 11 and the second tube body 13 are quartz glass tubes, the laser welding method is particularly suitable.

Specifically, as a method of fusing the first optical fiber 20 in the first tubular body 11, for example, the first optical fiber 20 may be first inserted into the first tubular body 11 and the first optical fiber may be surrounded by a laser light source (for example, a pulsed laser light source). The axial direction of 20 is irradiated to a predetermined position of the first optical fiber 20 to be in a partially molten state, so that the first optical fiber 20 and the first tubular body 11 form a good fusion. Similarly, the second optical fiber 30 can be inserted into the second tube body 13 and irradiated to a predetermined position of the second optical fiber 30 around the axial direction of the second optical fiber 30 using a laser light source (for example, a pulsed laser light source) to be in a partially molten state. Therefore, the second optical fiber 30 forms a good fusion with the first tubular body 13.

In addition, in the present embodiment, the first optical fiber 20 and the second optical fiber 30 may be single mode fibers or multimode fibers. That is, the first optical fiber 20 and the second optical fiber 30 may be single mode optical fibers. In addition, the first optical fiber 20 and the second optical fiber 30 may also be multimode optical fibers. In general, single mode fiber transmits only one mode, with small attenuation, long transmission distance, and transmission speed of single mode fiber. The rate is higher than that of multimode fiber, and the core diameter is smaller than that of multimode fiber. In contrast, multimode fiber can transmit multiple modes, but the attenuation is large and the transmission distance is short. In the present embodiment, a single mode fiber or a multimode fiber may be selected depending on the situation.

Additionally, in some examples, the first fiber 20 and the second fiber 30 may also be polarization-maintaining fibers or photonic crystal fibers. Moreover, in some examples, the first fiber 20 and the second fiber 30 may also be other types of fibers than single mode fibers, multimode fibers, polarization maintaining fibers, and photonic crystal fibers.

In addition, in the present embodiment, the first light guiding end surface 21 of the first optical fiber 20 may be perpendicular to the axial direction of the hollow tubular body 10, and the second light guiding end surface 31 of the second optical fiber 30 may be combined with the hollow tubular body 10. The axis direction is vertical. In this case, it is possible to ensure that the light guiding path of the first optical fiber 20 and the light guiding path of the second optical fiber 30 are substantially parallel to the axial direction of the hollow tubular body 10, whereby the first guiding of the first optical fiber 20 can be ensured. The measurement sensitivity of the Fabry cavity formed by the light end face 21 and the second light guiding end face 22 of the second optical fiber 20.

The first light guiding end surface 21 of the first optical fiber 20 may have a smooth surface, and the second light guiding end surface 31 of the second optical fiber 30 may have a smooth surface. In this case, the optical signal can be transmitted from the first light guiding end surface 21 along the first optical fiber 20, and incident and reflected from the second light guiding end surface 31 of the second optical fiber 30, on the first light guiding surface 21 and A Faber cavity is formed between the two light guiding faces 31 to generate an interference wave, and a part of the optical signal propagates along the second optical fiber 30.

In some examples, as described above, the first light guiding end surface 21 of the first optical fiber 20 may have an optical coating, and the second light guiding end surface 31 of the second optical fiber 30 may have an optical coating. In this case, the optical performance of the first light guiding end face 21 and the second light guiding end face 31 can be improved, and the measurement sensitivity can be further improved.

Further, in the present embodiment, the hollow tubular body 10 may have a central symmetry line, and the cavity portion 12 may be formed in a rotationally symmetrical structure around the central symmetry line. In this case, since the cavity portion 12 is a rotationally symmetrical structure about its central symmetry line, the cavity portion 12 can uniformly induce a change in external stress, whereby the optical fiber Fabry sensor 1 can be further improved. Sensitivity.

In some examples, the cavity portion 12 can be a generally hollow spheroid or a hollow ellipsoid. In this case, the cavity portion 12 can more uniformly sense the change in the external stress, whereby the sensitivity of the fiber Fabry sensor 1 can be further improved.

FIG. 5 is a schematic perspective structural view showing a modification of the optical fiber sensor according to the embodiment.

In the present embodiment, in the hollow pipe body, two or more cavity portions are disposed between the first pipe body 11 and the second pipe body 13. In some examples, as shown in FIG. 5, a cavity portion 12a and a cavity portion 12b are disposed between the first pipe body 11 and the second pipe body 13. In this case, the sensitivity of the fiber Fabry sensor can be further improved.

In the present embodiment, the cavity portion 12a and the cavity portion 12b may have identical or symmetrical shapes. In this case, the sealed space formed by the cavity portion 12a and the cavity portion 12b can also improve the sensitivity of the measurement.

In the present embodiment, the cavity portion 12a and the cavity portion 12b may be continuously formed. Additionally, in some examples, the cavity portion 12a and the cavity portion 12b may have overlapping portions.

Further, in some examples, three, five or more cavity portions may also be provided between the first tubular body 11 and the second tubular body 13. The specific number of the cavity portions can be selected according to the measurement sensitivity and accuracy of the actual application. Further, the plurality of cavity portions may have overlapping portions with each other.

In addition, in the present embodiment, the first optical fiber 20 and the hollow tubular body 10 may be formed with a first fusion joint 41, and the second optical fiber 30 and the hollow tubular body 10 may be formed with a second fusion joint 42, and at the first The hollow tube body 10 is between the weld 41 and the second weld 42. In this case, the measurement sensitivity of the fiber Fabry sensor 1 can be further improved.

The first pipe body 11, the cavity portion 12 and the second pipe body 13 are preferably integrally formed in consideration of an improvement in sealing property and ease of manufacture. In this case, the sealing property of the hollow tubular body 10 can be improved, and the sensitivity of the optical fiber Fabry sensor 1 can be improved. Additionally, in some examples, the first tubular body 11, the cavity portion 12, and the second tubular body 13 may be made of one tubular body.

Hereinafter, a method of manufacturing the optical fiber sensor 1 according to the present embodiment will be described in detail with reference to FIGS. 6 and 7a to 7e.

FIG. 6 is a flowchart showing the manufacture of the optical fiber sensor according to the embodiment. 7a to 7e are schematic views showing a hollow tubular body for manufacturing an optical fiber Fabry-Perot sensor according to the present embodiment.

In the present embodiment, in the method of manufacturing the optical fiber Fabry sensor 1, first, the hollow tubular body 10 is prepared, and the wall thickness of the hollow tubular body located at a predetermined portion of the hollow tubular body 10 is thinned (steps) S10). In addition, in the present embodiment, the prepared hollow tube body can It is a quartz glass tube. In this case, the high temperature resistance of the hollow tubular body and the process suitability of the hollow tubular body can be ensured.

In some examples, the predetermined location may be a substantially central location of the hollow tubular body. In addition, the thinning method in step S10 can be realized by a processing method such as etching by etching, laser, plasma or sand blasting. In this case, the thinning of the hollow tubular body can be easily achieved.

In step S10, the step of thinning may include: patterning an outer wall of a predetermined portion of the hollow tube body to form an etching window at a predetermined portion; and etching the patterned hollow tube body To form a groove structure at a predetermined portion, so that the wall thickness of the predetermined portion is smaller than the wall thickness around the predetermined portion. In this case, the thinning of the hollow tubular body is achieved by an etching process, whereby the cavity portion can be conveniently prepared.

In step S10, the step of patterning may include: coating a protective layer on the outer wall of the hollow tubular body; rotating the hollow tubular body coated with the protective layer around the central axis of the hollow tubular body and performing masking Etching; and developing the protective layer to remove the protective layer of the predetermined portion. In this case, the selection of the preset portion can be easily realized by the photolithography process, thereby improving the applicability of the fiber optic sensor sensor preparation.

Specifically, referring to Figures 7a and 7b, a protective layer 51 is applied to the prepared hollow tube body 10 such as a hollow quartz glass tube, and then a mask layer is adhered to the protective layer 51 (see the mask of Fig. 7c). Layer 52a, mask layer 52b). Then, development exposure is performed, and the protective layer 51 of the predetermined portion of the hollow tube body 10 is removed. Then, etching (for example, dry etching, wet etching) is performed to thin the hollow tube body of the exposed predetermined portion, and the hollow tube body 10 having the groove shown in FIG. 7d is obtained.

In the above examples, the mask layer may be a plastic film. Thereby, the etching mask can be conveniently realized, which greatly saves the cost of the etching process. Additionally, in other examples, the protective layer can also be a UV sensitive photoresist.

Next, the hollow tubular body 10 is filled with a heat-expandable substance, and both ends of the hollow tubular body are sealed (step S20). In step S20, the heat-expandable substance may be air, an inert gas or an easily gasified substance or the like. Here, the gasification substance may be, for example, an easily vaporizable liquid.

Next, the hollow pipe body 10 may be heated to thermally expand the predetermined portion to form a cavity portion, thereby forming a hollow pipe body including the first pipe body, the cavity portion, and the second pipe body which are sequentially disposed (step S30). Thereby, it is possible to thermally expand the predetermined portion by heating to generate the required The cavity portion 12 (see Figure 7e).

In the present embodiment, after the preparation of the hollow tubular body 10 is completed, the first optical fiber may be fixed to the first tubular body, the second optical fiber may be fixed to the second tubular body, and the first optical guide of the first optical fiber may be The end face and the second light guiding end face of the second optical fiber are disposed in the cavity portion and separated by a predetermined distance (step S40). In step S40, the first optical fiber may be fixed to the first pipe body by welding, and the second optical fiber may be fixed to the second pipe body by welding.

In the manufacturing method according to the present embodiment, the wall thickness is reduced by thinning at a predetermined portion of the hollow tubular body, and therefore, when the hollow tubular body is filled with a heat-expandable substance and heated, The hollow tube body of the predetermined portion is expanded to form a cavity portion, and then the first optical fiber and the second optical fiber are welded to the hollow tube body, and the light guiding end surface of the first optical fiber is separated from the light guiding end surface of the second optical fiber Provided, it is possible to form a fiber optic Fabry-Perot sensor with improved sensitivity. Further, in the above manufacturing method, the width of the free spectral region can be changed by adjusting the distance between the inner end faces of the two optical fibers (the first optical fiber and the second optical fiber).

Hereinafter, another manufacturing method of the optical fiber sensor 1 according to the present embodiment will be described in detail with reference to FIGS. 8 and 9a to 9e.

In the present embodiment, in the method of manufacturing the optical fiber Fabry sensor 1, as shown in FIGS. 9a and 9b, first, a hollow tubular body is prepared, and the first optical fiber is inserted into and closed at one end of the hollow tubular body (step S100). . In step S100, both end faces of the hollow tube (for example, a quartz glass tube) may be a flat end surface. In addition, the outer diameter of the first optical fiber matches the inner diameter of the hollow quartz glass tube.

In addition, in step S100, the first optical fiber may be fixed in the hollow tubular body by a welding method. The first optical fiber and the hollow tubular body can be realized by a fiber fusion splicer. Further, in the present embodiment, the prepared hollow tubular body may be a quartz glass tube. In this case, the high temperature resistance of the hollow tubular body and the process suitability of the hollow tubular body can be ensured. In addition, the hollow tube body may also be a high temperature resistant glass tube, a hollow fiber or a photonic crystal fiber.

Next, as shown in Fig. 9c, the other end of the hollow tubular body is connected to a high pressure source (step S200). In this case, a closed space is formed in the hollow tube body. In step S200, the air pressure inside the hollow tube body can be adjusted by adjusting the high pressure source.

Next, the hollow tube body is discharged (see FIG. 9d), and the predetermined portion is thermally expanded to form a cavity portion, thereby forming a hollow tube including the first tube body, the cavity portion, and the second tube body which are sequentially disposed. Body (step S300). Thereby, the predetermined portion can be thermally expanded by heating to generate the The required cavity portion 12 (see Figure 9e). In step S300, the high-pressure state of the hollow tube body can be maintained by adjusting the discharge time and discharge intensity parameters of the fiber fusion splicer, and discharging at a suitable position of the hollow tube body. In this case, since the internal air pressure of the hollow tubular body is higher than the external air pressure, the discharge position (predetermined portion) S (see FIG. 9d) of the hollow tubular body gradually expands to form a cavity portion such as a hollow microbubble.

In this embodiment, after the preparation of the hollow tubular body 10 is completed, the second optical fiber can be inserted and fixed to the second tubular body, and the first light guiding end surface of the first optical fiber and the second guiding end of the second optical fiber can be The light end faces are disposed in the cavity portion and spaced apart by a predetermined distance (step S400).

Further, in the above manufacturing method, a plurality of discharge positions may be selected, and step S300 is repeated, whereby a plurality of cavity portions can be obtained, that is, a plurality of cavities are formed between the first pipe body and the second pipe body. unit.

In the manufacturing method according to the embodiment, the hollow tube body of the predetermined portion is expanded to form a cavity portion by discharging at a predetermined portion of the hollow tube body, and then the first optical fiber and the second optical fiber are welded. In the hollow tube body, the light guiding end surface of the first optical fiber is spaced apart from the light guiding end surface of the second optical fiber, whereby an optical fiber Fabry sensor having improved sensitivity can be formed. Further, in the above manufacturing method, the width of the free spectral region can be changed by adjusting the distance between the inner end faces of the two optical fibers (the first optical fiber and the second optical fiber).

Hereinafter, the present embodiment will be described in further detail in conjunction with an embodiment of a method of manufacturing the optical fiber Fabry sensor 1.

[Example 1]

In the present embodiment, the two end faces of the hollow quartz glass tube having an inner diameter of about 100 um to 300 um and an outer diameter larger than the inner diameter and about 200 um to 400 um are cut flat by a fiber cutter. Next, one end of the hollow quartz glass tube was collapsed and closed using a fiber fusion splicer (model: FITEL S183 Version 2), and the other end was connected to a pressure suppressor (model: Const 162 type).

Next, the presser is adjusted so that the internal pressure of the hollow quartz glass tube reaches between 110 kPa and 120 kPa (absolute pressure). Adjust the discharge time of the fiber fusion splicer to 400ms to 1000ms, the discharge intensity is 50 units to 200 units, maintain the internal pressure of the hollow quartz glass tube, and discharge it 3-6 times at its proper position. In this process, due to the internal and external pressure difference of the hollow quartz glass tube, the discharge portion of the hollow quartz glass tube expands to form a substantially hollow spherical body (for example, microbubbles).

Then, the hollow quartz glass tube with the cavity portion is removed from the optical fiber fusion splicer, the high voltage source is removed, and both ends are re-cut with a fiber cutter. In the manual mode of the fusion splicer, two optical fibers (type: Changfei G652D) that are flattened at both ends are inserted into the hollow quartz glass tube with hollow spherical bodies in turn, and the discharge time is re-adjusted from 400ms to 1000ms. The discharge intensity is 50 units to 200 units, and the two fibers are respectively welded to the hollow quartz glass tube, and the distance between the inner end faces of the two fibers is adjusted during the welding process, so that the distance is about 5 um to 100 um. The free spectral region has a width of about 2.4 nm to 48 nm. At this time, the diameter of the hollow spherical body is about 200 um to 500 um, the thinnest wall thickness is about 2 um to 6 um, and the sensitivity of the sensor is about 200 pm / μ ε to 800 pm / μ ε.

[Embodiment 2]

In the present embodiment, the two end faces of the hollow quartz glass tube 2 having an inner diameter of about 100 um to 300 um and an outer diameter larger than the inner diameter and about 200 um to 400 um are cut flat by a fiber cutter. Next, one end of the hollow quartz glass tube was collapsed and closed using a fiber fusion splicer (model: FITEL S183 Version 2), and the other end was connected to a pressure suppressor (model: Const 162 type).

Then, the fiber fusion splicer electrode is moved from 300 um to 800 um from the center of the hollow spheroid, and the above steps are repeated to obtain another hollow spheroid. Next, the hollow quartz glass tube with two hollow spherical bodies was removed from the optical fiber fusion splicer, the high voltage source was removed, and both ends were re-cut with a fiber cutter. In the manual mode of the fusion splicer, two optical fibers (model: Changfei G652D) that are flattened at both ends are inserted into the hollow quartz glass tube with the cavity portion in turn, and the discharge time is re-adjusted from 400ms to 1000ms. The discharge intensity is 50 units to 200 units, and the two fibers are respectively welded to the hollow quartz glass tube, and the distance between the inner end faces of the two fibers is adjusted to 50 units to 200 units during the welding process. The width is about 1.2 nm to 30 nm. At this time, the diameters of the two hollow spheroids are respectively about 200 um to 400 um, the thinnest wall thickness is about 2 um to 6 um, and the sensitivity of the sensor is about 200 pm / μ ε to 800 pm / μ ε.

[Second Embodiment]

FIG. 10 is a schematic perspective view showing a fiber optic sensor according to a second embodiment of the present invention. 11a to 11e are schematic views showing the manufacture of the fiber optic sensor of FIG. 10, wherein FIG. 11a is a perspective view showing the hollow tube; FIG. 11b is a view showing the first fiber fixed and closed. FIG. 11c is a schematic cross-sectional view taken along line CC of FIG. 11b; FIG. 11d is a perspective view showing discharge of the hollow tube shown in FIG. 11c; FIG. 11e is a schematic view A stereo schematic of the prepared hollow tube body is shown.

The optical fiber sensor 1A according to the present embodiment is different from the optical fiber sensor 1 according to the first embodiment in that the first light guiding end surface 21 of the first optical fiber 20 and the second light guiding end of the second optical fiber 30 are different. End faces 31 are respectively disposed at both ends of the hollow pipe body 10 (see Fig. 10).

In the present embodiment, when the measurement is performed by the optical fiber sensor 1A according to the present embodiment, external mechanical parameters (stress, tensile force, pressure, etc.) can be transmitted through the thin portion of the cavity portion, and the The change in the length of the Faber cavity formed by the end face 21 of the optical fiber 20 and the end face 31 of the second optical fiber 30 effectively reflects the change in the corresponding mechanical parameter. Therefore, the optical fiber Fabry sensor 1A according to the present embodiment can also be effective. Improve the measurement sensitivity of the target mechanical parameters.

The method of manufacturing the optical fiber sensor 1A according to the first embodiment is basically the same as the method of manufacturing the optical fiber sensor 1 according to the first embodiment, and the optical fiber sensor 1 according to the first embodiment can be directly used. The method differs in that, in the manufacturing process, the end face 21 of the first optical fiber 20 needs to be in contact with one end of the hollow tubular body 10, and the end face 31 of the second optical fiber 30 and the other end of the hollow tubular body are required. The department meets. Specifically, in FIG. 11b, the end face of the first optical fiber 20 is in contact with one end of the hollow tubular body 10, and after the discharge heating step of FIGS. 11c and 11c, the end face of the second optical fiber 30 is hollow. The other end of the tube is connected. Thereby, the fiber optic sensor 1A shown in FIG. 10 or FIG. 11e is obtained.

In the present embodiment, the outer diameter of the first optical fiber 20 may be larger than the inner diameter of the first tubular body 11 of the hollow tubular body 10 (for example, a quartz glass tube), and the outer diameter of the second optical fiber 30 may be larger than that of the hollow tubular body 10. The inner diameter of the second tube body 13.

In addition, in some examples, the outer diameter of the first optical fiber 20 may be smaller than the outer diameter of the first tubular body 11 of the hollow tubular body 10 (eg, a quartz glass tube), and the outer diameter of the second optical fiber 30 may be smaller than the hollow tubular body. The outer diameter (not shown) of the second tubular body 13 of 10. In this case, the first optical fiber 20 and the first tubular body 11, and the second optical fiber 30 and the second tubular body 13 can also form a good connection.

Moreover, in other examples, the outer diameter of the first optical fiber 20 may be equal to or greater than the outer diameter of the first tubular body 11 of the hollow tubular body 10 (eg, a quartz glass tube), and the outer diameter of the second optical fiber 30 may be equal to or It is larger than the outer diameter (not shown) of the second pipe body 13 of the hollow pipe body 10. In this case, the first optical fiber 20 and the first tubular body 11, and the second optical fiber 30 and the second tubular body 13 can form a good connection.

While the invention has been described in detail with reference to the drawings and embodiments, it is understood that The present invention may be modified and changed as needed by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations are within the scope of the invention.

Claims

A fiber optic Fabry sensor, characterized in that

include:

a hollow tubular body having a first tubular body, a cavity portion and a second tubular body arranged in this order along the axial direction;

a first optical fiber disposed in the first tube along the axial direction, the first optical fiber having a first light guiding end surface disposed in the cavity portion;

a second optical fiber disposed in the second tube along the axial direction, the second optical fiber having a second light guiding end surface disposed in the cavity portion,

The first light guiding end surface is opposite to the second light guiding end surface by a predetermined distance, and the inner diameter of the cavity portion is larger than any one of the first tube body and the second tube body Inner diameter.
A fiber optic Fabry sensor, characterized in that

include:

a hollow tubular body having a first tubular body, a cavity portion and a second tubular body arranged in this order along the axial direction;

a first optical fiber having a first light guiding end surface that is in contact with an end of the first tube;

a second optical fiber having a second light guiding end surface that is in contact with an end of the second tube body,

The first light guiding end surface and the second light guiding end surface are oppositely disposed across the hollow tube body, and an inner diameter of the cavity portion is larger than the first tube body and the second tube body The inner diameter of any one of the tubes.
The fiber optic Fabry-Perot sensor according to claim 1 or 2, wherein

The first optical fiber is welded to the first pipe body, and the second optical fiber is welded to the second pipe body.
The fiber optic sensor sensor according to claim 1 or 2, wherein:

The first optical fiber and the second optical fiber are single mode fiber, multimode fiber, and polarization maintaining fiber Or photonic crystal fiber.
The fiber optic sensor sensor according to claim 1 or 2, wherein:

The first tube body, the cavity portion, and the second tube body are continuously formed, and a central axis of symmetry of the first tube body coincides with a central axis of symmetry of the second tube body.
The fiber optic sensor sensor according to claim 1 or 2, wherein:

The first light guiding end surface of the first optical fiber is perpendicular to the axial direction, and the second light guiding end surface of the second optical fiber is perpendicular to the axial direction.
The fiber optic sensor sensor according to claim 1 or 2, wherein:

The hollow tubular body has a central symmetry line, and the cavity portion is formed into a rotationally symmetrical structure around the central symmetry line.
The fiber optic sensor sensor according to claim 1 or 2, wherein:

In the hollow tubular body, two or more of the cavity portions are disposed between the first tubular body and the second tubular body.
The fiber optic sensor sensor of claim 3 wherein:

The first optical fiber and the hollow tube body are formed with a first fusion joint, and the second optical fiber and the hollow tubular body are formed with a second fusion joint.
The fiber optic sensor sensor according to claim 1 or 2, wherein:

The first tube body, the cavity portion and the second tube body are integrally formed.
The fiber optic sensor sensor according to claim 1 or 2, wherein:

The hollow tube body is a quartz glass tube, a high temperature resistant glass tube, a hollow fiber or a photonic crystal fiber.
A method for manufacturing a fiber optic Fabry sensor, characterized in that:

include:

Preparing a hollow tubular body and reducing the wall thickness at a predetermined portion of the hollow tubular body thin;

Filling the hollow tube body with a heat-expandable substance to seal both ends of the hollow tube body;

Heating the hollow tube body to thermally expand the predetermined portion to form a cavity portion, thereby forming a hollow tube body including the first tube body, the cavity portion and the second tube body arranged in sequence ;

Fixing the first optical fiber to the first tube, fixing the second optical fiber to the second tube, and making the first light guiding end surface of the first optical fiber and the second light guiding of the second optical fiber The end faces are disposed within the cavity portion and spaced apart by a predetermined distance.
A method for manufacturing a fiber optic Fabry sensor, characterized in that:

include:

Preparing a hollow tubular body and thinning the wall thickness at a predetermined portion of the hollow tubular body;

Filling the hollow tube body with a heat-expandable substance to seal both ends of the hollow tube body;

Heating the hollow tube body to thermally expand the predetermined portion to form a cavity portion, thereby forming a hollow tube body including the first tube body, the cavity portion and the second tube body arranged in sequence ;

Fixing an end surface of the first optical fiber to an end of the first tubular body, fixing an end surface of the second optical fiber to an end of the second tubular body, and making an end surface of the first optical fiber and the second end The end faces of the fibers are opposite.
A method of manufacturing an optical fiber sensor according to claim 12 or 13, wherein:

The heat-expandable substance is air, an inert gas or an easily gasified substance.
A method of manufacturing a fiber optic Fabry-Perot sensor according to claim 12 or 13, wherein:

The thinning is achieved by a processing method of corrosion, laser, plasma or sand blasting.
A method of manufacturing a fiber optic Fabry-Perot sensor according to claim 12 or 13, wherein:

The step of thinning comprises:

Patterning an outer wall of the predetermined portion of the hollow tubular body to form an etched window at the predetermined portion;

The patterned hollow tube body is etched to form a groove structure at the predetermined portion, so that the wall thickness of the predetermined portion is smaller than the wall thickness around the predetermined portion.
A method of fabricating a fiber optic sensor according to claim 16 wherein:

The step of patterning includes:

Coating a protective layer on an outer wall of the hollow tubular body;

Rotating the hollow tube coated with the protective layer around a central axis of the hollow tube body and performing mask etching;

The protective layer is developed to remove the protective layer of the predetermined portion.
A method for manufacturing a fiber optic Fabry sensor, characterized in that

include:

Preparing a hollow tube body, inserting and closing one end of the hollow tube body;

Connecting the other end of the hollow tube body to a high voltage source;

Discharging the hollow tube body to thermally expand the predetermined portion to form a cavity portion, thereby forming a hollow tube body including the first tube body, the cavity portion and the second tube body arranged in sequence ;

The second optical fiber is inserted and fixed to the second tube body, and an end surface of the first optical fiber and an end surface of the second optical fiber are disposed in the cavity portion and separated by a predetermined distance.
A method for manufacturing a fiber optic Fabry sensor, characterized in that

include:

Preparing a hollow tube body, fixing an end surface of the first optical fiber to one end of the hollow tube body and closing one end of the hollow tube body;

Connecting the other end of the hollow tube body to a high voltage source;

Discharging the hollow tube body to thermally expand the predetermined portion to form a cavity portion, thereby forming a hollow tube including the first tube body, the cavity portion and the second tube body arranged in sequence body;

An end surface of the second optical fiber is fixed to the second tube body and the second tube body is closed.
A method of manufacturing a fiber optic Fabry-Perot sensor according to claim 18 or 19, wherein:

In discharging the hollow tubular body, the hollow tubular body is discharged at a plurality of predetermined portions to form a plurality of cavity portions.