An optical fiber sensor

Abstract

The utility model provides a kind of optical fiber sensor, including metal substrate, stainless steel pipe, optical fiber sensing component and ceramic adhesive layer, main groove body is opened thereon along axis, and it has the first slot section and second slot section with slot depth decreasing along the length direction of the main groove body;Stainless steel pipe is embedded in the first slot section;Optical fiber sensing component is embedded in the second slot section inside, so that the axis of the optical fiber sensing component coincides with the axis of the stainless steel pipe, and one end of the optical fiber sensing component is inserted in the inside of the stainless steel pipe;Ceramic adhesive layer is bonded between the optical fiber sensing component and the main groove body.The utility model is through the stepped first slot section and second slot section on the main groove body of metal substrate, respectively embed stainless steel pipe and optical fiber sensing component, the axis of optical fiber sensing component is aligned with the axis of stainless steel pipe, can limit the expansion of stainless steel pipe, eliminate the protrusion caused by transverse bending, improve the structural stability of optical fiber under high temperature condition.

Description

Technical Field

[0001] This utility model relates to the field of fiber optic sensing technology, and specifically to a fiber optic sensor. Background Technology

[0002] With the increasing demand for structural health monitoring under extreme environments in industries such as aerospace, nuclear energy, and gas turbines, high-temperature, high-strain measurement technology has become crucial for ensuring the safe operation of equipment. High-temperature strain sensors are typically used for detection. For example, Chinese Patent 202020390844.2 discloses a high-temperature strain sensor, including a substrate, an optical cable, and a strain measuring element. The strain measuring element is disposed within the optical cable and inserted into the substrate along with the optical cable. The substrate is used to attach to the element to be tested. The substrate, the optical cable, and the strain measuring element are all made of high-temperature resistant materials.

[0003] The existing technology has the following problems: Under extreme working conditions of high temperature, the different expansion coefficients of the stainless steel tube and the metal substrate can cause protrusions, which can lead to unstable connection and cross-movement, and generate shear force on the optical fiber. Utility Model Content

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose an optical fiber sensor that solves the technical problem in the prior art where thermal expansion of stainless steel tubes and metal substrates causes bulges, unstable connections, and movement that easily generate shear forces on optical fibers.

[0005] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0006] This utility model provides an optical fiber sensor, comprising:

[0007] A metal substrate has a main groove formed along its axis, and a first groove segment and a second groove segment with decreasing groove depth along the length direction of the main groove.

[0008] A stainless steel pipe is embedded in the first groove section;

[0009] An optical fiber sensing component is embedded inside the second slot section, such that the axis of the optical fiber sensing component coincides with the axis of the stainless steel tube, and one end of the optical fiber sensing component is inserted into the inner side of the stainless steel tube; and

[0010] A ceramic adhesive layer is bonded between the optical fiber sensing component and the main tank.

[0011] In some embodiments, the fiber optic sensing assembly includes a capillary glass tube, a single-mode fiber, and a fiber Bragg grating. One end of the single-mode fiber is connected to the inside of the capillary glass tube, and the other end is suspended outside the capillary glass tube. The fiber Bragg grating is inserted into the inside of the capillary glass tube and is opposite to the end of the single-mode fiber. A variable-length FP cavity is formed inside the capillary glass tube between the two end faces of the fiber Bragg grating and the single-mode fiber.

[0012] In some embodiments, the outer diameter of the stainless steel tube matches the depth of the first groove segment, and the outer diameter of the capillary glass tube matches the depth of the second groove segment.

[0013] In some embodiments, the main groove body has a first groove extending to both sides, and a metal gasket is connected in the first groove. The metal gasket covers the top of the stainless steel tube and is used to fasten the stainless steel tube to the metal substrate.

[0014] In some embodiments, a second groove extending to both sides is formed on the main groove, and the ceramic adhesive layer is disposed in the second groove and bonded to the fiber optic sensing component.

[0015] In some embodiments, the ceramic adhesive layer includes a first adhesive layer coated between the inner wall of the second groove and the capillary glass tube and the bottom of the fiber Bragg grating.

[0016] In some embodiments, the ceramic adhesive layer further includes a second adhesive layer that extends upward from the first adhesive layer to both sides of the capillary glass tube and the fiber Bragg grating.

[0017] In some embodiments, the number of the second grooves is two, which are respectively used for bonding the capillary glass tube and the fiber Bragg grating by the ceramic adhesive layer.

[0018] In some embodiments, the metal substrate is provided with a plurality of third grooves for spot welding to fix the metal substrate to the working position of the object being tested.

[0019] In some embodiments, the number of the third grooves is four, and they are evenly arranged on the metal substrate.

[0020] Compared with the prior art, the fiber optic sensor provided by this utility model, by embedding stainless steel tubes and fiber optic sensing components in the stepped first and second slots on the main slot of the metal substrate, and aligning the axis of the fiber optic sensing component with the axis of the stainless steel tube, can limit the expansion of the stainless steel tube, eliminate the protrusion caused by lateral bending, and improve the structural stability of the fiber optic under high temperature conditions. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the fiber optic sensing component of the fiber optic sensor provided in this embodiment of the utility model;

[0022] Figure 2 This is a structural diagram of the metal substrate of the fiber optic sensor provided in this embodiment of the present invention;

[0023] Figure 3 This is an assembly structure diagram of the fiber optic sensor provided in an embodiment of this utility model.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Metal substrate; 101. Main groove; 101a. First groove segment; 101b. Second groove segment; 101c. First groove; 101d. Second groove; 102. Third groove;

[0026] 2. Stainless steel pipe;

[0027] 3. Fiber optic sensing components; 31. Capillary glass tube; 32. Single-mode fiber; 33. Fiber Bragg grating; 34. FP cavity;

[0028] 4. Ceramic adhesive layer; 41. First adhesive layer; 42. Second adhesive layer;

[0029] 5. Metal gasket. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0031] To address the technical problem of protrusions caused by thermal expansion of the stainless steel tube and metal substrate, which leads to unstable connection and shearing force on the optical fiber, this invention provides an optical fiber sensor. This sensor embeds a stainless steel tube and an optical fiber sensing component in a stepped first and second groove segment on the main groove of the metal substrate, respectively. Aligning the axis of the optical fiber sensing component with the axis of the stainless steel tube limits the expansion of the stainless steel tube, eliminates protrusions caused by lateral bending, and improves the structural stability of the optical fiber under high-temperature conditions.

[0032] Please see Figure 1-3This utility model provides an optical fiber sensor, which includes a metal substrate 1, a stainless steel tube 2, an optical fiber sensing component 3, and a ceramic adhesive layer 4. The metal substrate 1 has a main groove 101 formed along its axis, and has a first groove segment 101a and a second groove segment 101b with decreasing groove depth along the length direction of the main groove 101. The stainless steel tube 2 is embedded in the first groove segment 101a. The optical fiber sensing component 3 is embedded inside the second groove segment 101b, such that the axis of the optical fiber sensing component 3 coincides with the axis of the stainless steel tube 2, and one end of the optical fiber sensing component 3 is inserted into the inside of the stainless steel tube 2. The ceramic adhesive layer 4 is bonded between the optical fiber sensing component 3 and the main groove 101. The stepped first groove segment 101a and second groove segment 101b formed by the main groove body 101 structure on the metal substrate 1, under the embedded restrictive stainless steel tube 2 structure, are aligned with the axis of the optical fiber sensing component 3. This can effectively solve the problem that under extreme working conditions of high temperature, the different expansion coefficients of the stainless steel tube 2 and the metal substrate 1 cause protrusion, resulting in connection instability and movement, and generating shear force on the optical fiber.

[0033] Understandably, the first groove section forms a strong constraint on the stainless steel tube 2 embedded therein, and its expansion is suppressed by the metal substrate 1, converting the shear force into an axial force. The axial force is limited by the steps between the stepped grooves. Furthermore, the fiber optic sensing component 3 is in a plugged-in state and is not fixed to the stainless steel tube 2, so it will not have a significant impact on the fiber optic sensing component 3 along the axial direction.

[0034] In one embodiment, please refer to Figure 2 The fiber optic sensing assembly 3 includes a capillary glass tube 31, a single-mode fiber 32, and a fiber Bragg grating 33. One end of the single-mode fiber 32 is connected to the inside of the capillary glass tube 31, and the other end is suspended outside the capillary glass tube 31. That is, one end of the single-mode fiber 32 is inserted into the capillary glass tube 31 and fused to it. The other end of the single-mode fiber 32 passes through the capillary glass tube 31. The fiber Bragg grating 33 is inserted into the inside of the capillary glass tube 31 and is opposite to the end of the single-mode fiber 32. A variable-length FP cavity 34 is formed between the two end faces of the fiber Bragg grating 33 and the single-mode fiber 32 within the capillary glass tube 31. The end of the fiber Bragg grating 33 inserted into the capillary glass tube 31 moves freely, and the other end of the fiber Bragg grating 33 is inserted into the stainless steel tube 2.

[0035] In one embodiment, please refer to Figure 2 and Figure 3 The outer diameter of the stainless steel tube 2 matches the groove depth of the first groove section 101a, and the outer diameter of the capillary glass tube 31 matches the groove depth of the second groove section 101b, so that it can be stably installed.

[0036] The high-temperature resistant metal gasket is made of RA330, and the metal substrate is made of GH3039.

[0037] In one embodiment, please refer to Figure 2 and Figure 3 In order to fix the stainless steel pipe 2, the main groove 101 is provided with a first groove 101c that extends to both sides. A metal gasket 5 is connected in the first groove 101c. The metal gasket 5 covers the top of the stainless steel pipe 2 and is used to fasten the stainless steel pipe 2 to the metal base plate 1. The metal gasket 5 is fixed to the metal base plate 1 by welding, thereby fastening the stainless steel pipe 2 below it.

[0038] In one embodiment, please refer to Figure 2 and Figure 3 In order to provide sufficient space for the ceramic adhesive layer 4 and form a strong bond, a second groove 101d extending to both sides is provided on the main groove 101. The ceramic adhesive layer 4 is disposed in the second groove 101d and bonded to the optical fiber sensing component 3. The second groove 101d provides the coating space for the ceramic adhesive layer 4.

[0039] Understandably, ceramic adhesive layer 4 is a high-temperature ceramic adhesive.

[0040] Furthermore, in order to provide basic adhesion, the ceramic adhesive layer 4 includes a first adhesive layer 41, which is coated between the inner wall of the second groove 101d and the bottom of the capillary glass tube 31 and the fiber Bragg grating 33 to form a stable adhesion at the bottom and ensure that the thickness of the adhesive does not exceed that of the single-mode fiber 32 and the fiber Bragg grating 33.

[0041] Furthermore, in order to improve the bonding strength, the ceramic adhesive layer 4 also includes a second adhesive layer 42, which extends upward from the first adhesive layer 41 to both sides of the capillary glass tube 31 and the fiber Bragg grating 33.

[0042] Specifically, a thin, uniform layer of high-temperature ceramic adhesive is first applied to the second groove 101d. Then, a small amount of additional high-temperature ceramic adhesive is applied along the axial direction of the fiber Bragg grating 33 and the capillary glass tube 31 to ensure reliable fixation. This adhesive application method effectively alleviates stress concentration caused by the difference in thermal expansion coefficients between the high-temperature ceramic adhesive and the metal substrate, preventing fiber breakage or connection failure due to the high-temperature ceramic adhesive detaching from the metal substrate.

[0043] There are two second grooves 101d, which are used to bond the capillary glass tube 31 and the fiber Bragg grating 33 to the ceramic adhesive layer 4, respectively.

[0044] In one embodiment, please refer to Figure 2 and Figure 3 The metal substrate 1 is provided with a plurality of third grooves 102 for spot welding to fix the metal substrate 1 to the working position of the object being tested.

[0045] Specifically, there are four third grooves 102, which are evenly arranged on the metal substrate 1 to ensure stable welding and installation.

[0046] To better understand this utility model, the following is combined with... Figures 1 to 3 The technical solution of this utility model is described in detail, mainly including the following packaging steps:

[0047] Step 1: Remove the coating layers from the single-mode fiber 32 and the fiber Bragg grating 33;

[0048] Step 2: Insert one end of the single-mode fiber 32 into the capillary glass tube 31, and ensure that the other end of the single-mode fiber 32 is freely suspended outside the capillary glass tube 31; fused the end of the single-mode fiber 32 inserted into the capillary glass tube 31 with the capillary glass tube 31.

[0049] Step 3: Insert one end of the fiber Bragg grating 33 into the capillary glass tube 31, control the length inserted into the capillary glass tube 31 to ensure the length of the FP cavity 34, and complete the fabrication of the fiber optic Fabry-Perot cavity high-temperature strain sensor.

[0050] Step 4: Place the fiber optic epoch high-temperature strain sensor, i.e., the fiber optic sensing component 3, into the groove structure inside the metal substrate 1, i.e. the main groove 101, ensuring that the capillary glass tube 31 is embedded in the second groove segment 101b, and embed the stainless steel tube 2 into the first groove segment 101a. At the same time, insert the other end of the fiber Bragg grating 33 into the stainless steel tube 2, which is a long and thin tube.

[0051] Step 5: Apply the high-temperature ceramic adhesive evenly and thinly to the second groove 101d of the metal substrate 1, ensuring that the thickness of the adhesive layer 41 does not exceed that of the single-mode fiber 32 and the fiber Bragg grating 33. Apply a small amount of high-temperature ceramic adhesive again to both sides of the single-mode fiber 32 and the fiber Bragg grating 33 to complete the fixation, i.e., the second adhesive layer 42.

[0052] Step 6: Cover the high-temperature resistant metal gasket 5 on the thin stainless steel tube 2 to ensure that it is aligned with the first groove 101c of the metal substrate 1, and use a spot welding machine to weld and fix the high-temperature resistant metal gasket 5 to the metal substrate 1.

[0053] The specific embodiments of this utility model described above do not constitute a limitation on the scope of protection of this utility model. Any other corresponding changes and modifications made based on the technical concept of this utility model should be included within the scope of protection of the claims of this utility model.

Claims

1. An optical fiber sensor, characterized in that, include: A metal substrate has a main groove formed along its axis, and a first groove segment and a second groove segment with decreasing groove depth along the length direction of the main groove. A stainless steel pipe is embedded in the first groove section; An optical fiber sensing component is embedded inside the second slot section, such that the axis of the optical fiber sensing component coincides with the axis of the stainless steel tube, and one end of the optical fiber sensing component is inserted into the inner side of the stainless steel tube; and A ceramic adhesive layer is bonded between the optical fiber sensing component and the main tank.

2. The fiber optic sensor according to claim 1, characterized in that, The fiber optic sensing assembly includes a capillary glass tube, a single-mode fiber, and a fiber Bragg grating. One end of the single-mode fiber is connected to the inside of the capillary glass tube, and the other end is suspended outside the capillary glass tube. The fiber Bragg grating is inserted into the inside of the capillary glass tube and is opposite to the end of the single-mode fiber. A variable-length FP cavity is formed between the two end faces of the fiber Bragg grating and the single-mode fiber inside the capillary glass tube.

3. The fiber optic sensor according to claim 2, characterized in that, The outer diameter of the stainless steel tube matches the depth of the first groove section, and the outer diameter of the capillary glass tube matches the depth of the second groove section.

4. The fiber optic sensor according to claim 1, characterized in that, The main groove is provided with a first groove that extends to both sides. A metal gasket is connected in the first groove. The metal gasket covers the top of the stainless steel tube and is used to fasten the stainless steel tube to the metal substrate.

5. The fiber optic sensor according to claim 2, characterized in that, The main groove is provided with a second groove that extends to both sides. The ceramic adhesive layer is disposed in the second groove and is bonded to the fiber optic sensing component.

6. The fiber optic sensor according to claim 5, characterized in that, The ceramic adhesive layer includes a first adhesive layer, which is coated between the inner wall of the second groove and the capillary glass tube and the bottom of the fiber Bragg grating.

7. The fiber optic sensor according to claim 6, characterized in that, The ceramic adhesive layer further includes a second adhesive layer, which extends upward from the first adhesive layer to both sides of the capillary glass tube and the fiber Bragg grating.

8. The fiber optic sensor according to claim 7, characterized in that, The second groove is of two types, which are used respectively for bonding the capillary glass tube and the fiber Bragg grating to the ceramic adhesive layer.

9. The fiber optic sensor according to claim 1, characterized in that, The metal substrate has several third grooves for spot welding to fix the metal substrate to the working position of the object being tested.

10. The fiber optic sensor according to claim 9, characterized in that, The number of the third grooves is four, and they are evenly arranged on the metal substrate.

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