A fiber-optic temperature sensing structure based on a capillary aluminum tube

Abstract

The utility model discloses a kind of optical fiber temperature sensing structure based on capillary aluminium pipe, it is related to optical fiber temperature sensing technical field, including optical fiber bragg grating, capillary aluminium pipe body and epoxy resin, the epoxy resin is filled in capillary aluminium pipe body inside, the optical fiber bragg grating is fixed in the center position of capillary aluminium pipe body, and using epoxy resin and capillary aluminium pipe body bonding fixed, form the temperature sensor body of integrated packaging structure;The device adopts the capillary aluminium pipe packaging of high expansion coefficient, so that the sensitivity of sensor reaches 38.35-38.4pm / ℃ in 10 ℃-90 ℃ range, about 3.4-3.5 times of bare optical fiber bragg grating, satisfy high-precision temperature measurement demand.

Description

Technical Field

[0001] This utility model relates to the field of fiber optic temperature sensing technology, specifically to a fiber optic temperature sensing structure based on a capillary aluminum tube. Background Technology

[0002] Temperature is one of the most critical physical quantities in industrial production, scientific research, and daily life, and the performance of temperature sensors directly affects measurement accuracy and application safety. Existing temperature sensors mainly include resistive, thermoelectric, PN junction, and radiation types, but they have many drawbacks: resistive sensors are prone to corrosion and short circuits, and have high manufacturing costs; thermoelectric sensors have low sensitivity and require additional compensation circuitry; radiation sensors are susceptible to environmental gas composition and electromagnetic interference; and traditional electronic sensors pose a risk of electrical sparks causing safety accidents in flammable and explosive environments.

[0003] Fiber optic temperature sensors have become the preferred solution for temperature measurement in special environments due to their advantages such as resistance to electromagnetic interference, no electrical sparks, small size, and low loss. Among them, fiber Bragg grating (FBG) sensors have attracted widespread attention due to their simple structure and industrial production capabilities. However, bare fiber Bragg gratings are mainly made of SiO2, which has problems such as fragile texture, small coefficient of thermal expansion (only 0.55×10^-6 / ℃), and low temperature sensitivity (about 11.191 pm / ℃), making it difficult to meet the needs of practical applications.

[0004] Existing FBG packaging methods include electroplating, metal soldering, and organic polymer packaging, but all have shortcomings: electroplating has limited metal layer thickness and poor protection; metal soldering is complex and difficult to mass-produce; organic polymer packaging has insufficient thermal expansion coefficient and limited sensitivity enhancement effect; structural packaging has limited applicability and poor flexibility. Therefore, there is an urgent need to design an FBG packaging structure that is simple in structure, highly sensitive, highly reliable, and mass-producible. Utility Model Content

[0005] The purpose of this invention is to provide a fiber optic temperature sensing structure based on a capillary aluminum tube, in order to solve the problem that the traditional FBG packaging method in the prior art cannot meet the requirements for accurate temperature measurement.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a fiber optic temperature sensing structure based on a capillary aluminum tube, comprising a fiber Bragg grating, a capillary aluminum tube body, and epoxy resin. The epoxy resin is filled inside the capillary aluminum tube body, and the fiber Bragg grating is fixed at the center of the capillary aluminum tube body. The fiber Bragg grating is bonded and fixed to the capillary aluminum tube body using epoxy resin to form an integrated encapsulated temperature sensor body.

[0007] Furthermore, the epoxy resin is used to fill the gap between the inner wall of the capillary aluminum tube body and the fiber Bragg grating, and after the epoxy resin is cured, a uniform adhesive layer is formed with a thickness of 0.1 to 0.3 mm.

[0008] Furthermore, the effective refractive index neff of the fiber Bragg grating core changes linearly with temperature, and the capillary aluminum tube body transmits uniform stress to the fiber Bragg grating through thermal expansion, thereby enhancing temperature sensitivity.

[0009] Compared with existing technologies, the advantages of the fiber optic temperature sensing structure based on capillary aluminum tubes provided by this utility model are as follows:

[0010] 1. The sensor is packaged with a capillary aluminum tube with a high coefficient of thermal expansion, which enables the sensor to achieve a sensitivity of 38.35-38.4 pm / ℃ in the range of 10℃-90℃, which is about 3.4-3.5 times that of a bare fiber Bragg grating, thus meeting the requirements for high-precision temperature measurement.

[0011] 2. The capillary aluminum tube is 0.5mm thick and bonded with epoxy resin, effectively protecting the fiber Bragg grating from bending and impact damage, thus solving the problem of the fragility of bare fiber Bragg gratings; after encapsulation, there is no risk of loosening or falling off, making it suitable for complex working conditions.

[0012] 3. The manufacturing process is simple and requires no complicated equipment. It can be completed simply by cutting, cleaning, epoxy resin bonding, and baking curing. The cost is low and it is suitable for industrial mass production. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings.

[0014] Figure 1 This is a schematic diagram of the overall structure of the device provided in an embodiment of the present utility model;

[0015] Figure 2 This is a schematic diagram of the internal structure of the device provided for an embodiment of the present utility model.

[0016] Explanation of reference numerals in the attached figures:

[0017] 1. Temperature sensor body; 2. Capillary aluminum tube body; 3. Fiber Bragg grating; 4. Epoxy resin. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings.

[0019] As attached Figure 1 To be continued Figure 2 As shown:

[0020] Example:

[0021] This invention provides a fiber optic temperature sensing structure based on a capillary aluminum tube, comprising a fiber Bragg grating 3, a capillary aluminum tube body 2, and epoxy resin 4. The fiber Bragg grating 3 is an SMF-28 type single-mode fiber grating with a grating region length of 10 mm, a pigtail length of 2 m, a reflectivity ≥85%, and a center operating wavelength of 1550 nm. The capillary aluminum tube body 2 has a length of 11 mm, an outer diameter of 3 mm, an inner diameter of 2 mm, a thickness of 0.5 mm, and a coefficient of thermal expansion of 23 × 10⁻⁶ / ℃. The fiber Bragg grating 3 is fixed at the center of the capillary aluminum tube body 2 and is bonded to the capillary aluminum tube body 2 using epoxy resin 4. The temperature sensor body 1 is an integrated package structure. Epoxy resin 4 is filled inside the capillary aluminum tube body 2. The epoxy resin 4 is used to fill the gap between the inner wall of the capillary aluminum tube body 2 and the fiber Bragg grating 3. After curing, the epoxy resin 4 forms a uniform adhesive layer with a thickness of 0.1-0.3 mm. The effective refractive index neff of the fiber core of the fiber Bragg grating 3 changes linearly with temperature. The capillary aluminum tube body 2 transmits uniform stress to the fiber Bragg grating 3 through thermal expansion, thereby enhancing temperature sensitivity. The integrated package structure has a temperature sensitivity ≥38 pm / ℃ and a linear correlation ≥0.993 in the temperature range of 10℃-90℃.

[0022] When making the fiber Bragg grating 3, first use alcohol to clean it to remove external dust, grease and other impurities. Since this experiment uses the center wavelength of the reflected wave of the fiber Bragg grating 3, after cleaning, cut off the excess pigtail to facilitate subsequent measurement work.

[0023] After preparing the fiber Bragg grating 3, the capillary aluminum tube is processed. Based on the length of the fiber Bragg grating 3, a capillary aluminum tube body 2 with a length of about 11mm is cut with a hacksaw. The capillary aluminum tube body 2 is polished with sandpaper. The main purpose is to make the cross-section of the aluminum tube uniform and smooth, and to ensure that the thickness of the aluminum tube is uniform. After this process, the external stress transmitted to the fiber Bragg grating 3 during thermal expansion and contraction is basically uniform. On the other hand, it can also eliminate the internal stress of the aluminum tube itself and reduce experimental errors. After polishing, the capillary aluminum tube body 2 is washed with water to remove the metal residue inside the tube. After drying, it is wiped with alcohol and ready for use.

[0024] After preparing the capillary aluminum tube body 2 and the fiber Bragg grating 3, the fiber Bragg grating 3 is encapsulated. Epoxy resin 4 is squeezed into a prepared syringe, and excess air is expelled. Then, one end of the needle is blocked by hand, and the piston is pulled outwards to reduce air bubbles inside the epoxy resin 4 using air pressure. Finally, the treated epoxy resin 4 is injected into the capillary aluminum tube body 2. The treated fiber Bragg grating 3 is then inserted into the capillary aluminum tube body 2 and fixed in the center. After 10 minutes, it is baked with a hair dryer to accelerate the solidification of the epoxy resin 4. Once the epoxy resin 4 has solidified, the sensor fabrication is basically complete. Figure 1 As shown.

[0025] The foregoing description only illustrates certain exemplary embodiments of the present invention. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A fiber optic temperature sensing structure based on a capillary aluminum tube, characterized in that, The temperature sensor body (1) includes a fiber Bragg grating (3), a capillary aluminum tube body (2), and epoxy resin (4). The epoxy resin (4) is filled inside the capillary aluminum tube body (2). The fiber Bragg grating (3) is fixed at the center of the capillary aluminum tube body (2) and is bonded to the capillary aluminum tube body (2) with epoxy resin (4) to form an integrated encapsulated structure.

2. The fiber optic temperature sensing structure based on a capillary aluminum tube according to claim 1, characterized in that, The epoxy resin (4) is used to fill the gap between the inner wall of the capillary aluminum tube body (2) and the fiber Bragg grating (3), and the epoxy resin (4) forms a uniform adhesive layer after curing, with an adhesive layer thickness of 0.1 to 0.3 mm.

3. The fiber optic temperature sensing structure based on a capillary aluminum tube according to claim 1, characterized in that, The effective refractive index neff of the fiber Bragg grating (3) changes linearly with temperature, and the capillary aluminum tube body (2) transmits uniform stress to the fiber Bragg grating (3) through thermal expansion, thereby enhancing temperature sensitivity.

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