Optical fiber loop assembly and sealing process method for improving long-term stability thereof

Abstract

This invention relates to fiber optic ring assemblies, specifically to a fiber optic ring assembly and a sealing process method to improve its long-term stability. This addresses the technical problems of existing fiber optic ring assemblies, such as the inability to guarantee the accuracy performance of the fiber optic ring when exposed to air, poor sealing performance at the small holes in the fiber optic ring shell, and slippage of the fiber optic ring and pigtails from the fiber optic ring shell due to weak adhesive. The invention includes a fiber optic ring shell and a fiber optic ring. The fiber optic ring shell includes a fiber optic ring frame and a cover plate, which are sealed together. The fiber optic ring is installed within the cavity formed by the fiber optic ring frame and the cover plate. The invention also includes a flexible absorbent material covering the fiber optic ring. The flexible absorbent material fills the space within the cavity of the fiber optic ring shell, excluding the space occupied by the fiber optic ring. A channel is provided on the fiber optic ring shell connecting the cavity to the outside. At least one pigtail of the fiber optic ring extends from this channel. The channel is sealed.

Description

Technical Field

[0001] This invention relates to fiber optic ring assemblies, and more specifically to a fiber optic ring assembly and a sealing process method for improving its long-term stability. Background Technology

[0002] As an angular velocity-sensitive inertial device, the fiber optic gyroscope has advantages such as being all-solid-state, highly accurate, having a short startup time, and a long lifespan. It is widely used in various inertial navigation fields such as aerospace, navigation, weaponry, and measurement, and has now become a crucial component of inertial navigation systems.

[0003] The fundamental principle of a fiber optic gyroscope is the Sagnac effect, where a fiber optic loop generates a phase difference by rotating around a fixed axis. This phase difference interferes at the point where the light converges in the Y-waveguide, achieving high-precision sensitivity between the output light intensity and the rotational angular velocity. Therefore, the fiber optic loop is crucial to the accuracy performance of the fiber optic gyroscope. In practical applications, the performance of the fiber optic loop is affected by external environmental factors such as temperature, humidity, and magnetic field changes. These environmental changes can easily cause significant drift in the fiber optic gyroscope's output. Therefore, the isolation and sealing of the fiber optic loop becomes a key assembly technology.

[0004] In the actual assembly process of fiber optic gyroscopes, to ensure the stable performance of the fiber optic ring assembly, the metal outer shell of the fiber optic ring is usually welded into a single unit. A small hole is made at the fiber optic pigtail inlet / outlet of the outer shell, and the pigtail and the outer shell are sealed using adhesive bonding. This method is convenient, simple, and inexpensive, and provides a certain degree of isolation from the outside environment. Currently, most fiber optic gyroscopes use this sealing method for their fiber optic ring assemblies. However, the fiber optic ring is still exposed to air, and there is a risk of slippage and detachment during high-speed motion, which compromises accuracy. For sealing the small hole in the outer shell, most adhesive materials cannot completely prevent the entry of gases or liquids, which can adversely affect the internal environment of the outer shell. During strong vibrations, the fiber optic ring and pigtail may slip off the outer shell due to weak adhesive bonding, significantly damaging the environmental stability of the fiber optic ring and affecting the long-term stability of the fiber optic gyroscope. Furthermore, the physical properties of the adhesive may change at higher ambient temperatures, reducing the sealing effectiveness at the adhesive bonding point, which is also one of the reasons for unstable output accuracy in fiber optic gyroscopes. Summary of the Invention

[0005] The purpose of this invention is to address the following technical problems in existing fiber optic ring assemblies: the fiber optic ring remains exposed to air, which may lead to slippage and detachment during high-speed movement, compromising accuracy and performance; for sealing the small holes in the fiber optic ring housing, most adhesive materials cannot completely prevent the entry of gas or liquid, adversely affecting the internal environment of the fiber optic ring housing; during strong vibrations in use, the fiber optic ring and pigtail may slip off the connection between the fiber optic ring and the housing due to weak adhesive, significantly damaging the environmental stability of the fiber optic ring and thus affecting the long-term stability of the fiber optic gyroscope; and the physical properties of the adhesive may change at higher ambient temperatures, leading to reduced sealing effectiveness at the adhesive application point. This invention provides a fiber optic ring assembly and a sealing process method to improve its long-term stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An optical fiber ring assembly includes an optical fiber ring housing and an optical fiber ring. The optical fiber ring housing includes an optical fiber ring skeleton and a cover plate. The optical fiber ring skeleton and the cover plate are sealed together. The optical fiber ring is installed within a cavity formed by the optical fiber ring skeleton and the cover plate. Its key feature is that:

[0008] It also includes flexible absorbent materials that cover fiber optic rings;

[0009] Flexible absorbent material is filled in the cavity of the fiber optic ring shell, excluding the space occupied by the fiber optic ring itself.

[0010] The fiber optic ring housing has a channel that connects the cavity of the fiber optic ring housing to the outside. The fiber optic ring pigtail is led out from the channel, and there is at least one pigtail. The channel is sealed.

[0011] Furthermore, the flexible absorbent material fills 75%-90% of the cavity in the fiber optic ring shell, excluding the space occupied by the fiber optic ring itself.

[0012] Furthermore, flexible water-absorbing material is injected into the cavity of the fiber optic ring shell, excluding the space occupied by the fiber optic ring, through the channel.

[0013] Furthermore, a section of the fiber coating on the pigtail is stripped off, and a metal sleeve is fitted over the outer side of the fiber cladding where the fiber coating has been stripped off, with the metal sleeve completely covering the fiber cladding where the fiber coating has been stripped off; the inner circumference of the metal sleeve and the outer circumference of the fiber cladding where the fiber coating has been stripped off are sealed together by a first welding layer.

[0014] A metal sleeve is inserted into the channel, and the outer circumference of the metal sleeve is sealed to the inner circumference of the channel through a second welded layer.

[0015] Furthermore, there are multiple pigtails, with multiple metal sleeves spaced apart from each other.

[0016] Furthermore, the length of the metal sleeve is defined as M, and the length of the fiber coating to be stripped is defined as L, where M≥L;

[0017] The two ends of the metal sleeve extend from the two ends of the channel, and the wall thickness of the fiber optic ring shell at the channel position is defined as N, M≥1.5×N;

[0018] The angle between the central axis of the metal sleeve and the central axis of the channel ranges from 0° to 5°.

[0019] Define the aperture of the channel as D, and the outer diameter of the metal sleeve as d, where D≥2×d;

[0020] The inner diameter of the metal sleeve ranges from 0.2 mm to 0.4 mm, and the outer diameter ranges from 0.4 mm to 1 mm.

[0021] Furthermore, the first welding layer is a glass welding layer;

[0022] The second welding layer is a metal welding layer;

[0023] The metal sleeve is made of nickel;

[0024] The flexible absorbent material is made of polyethylene resin;

[0025] The connection between the fiber optic ring frame and the cover plate is sealed by welding.

[0026] Meanwhile, the present invention also provides a sealing process method for improving the long-term stability of fiber optic ring assemblies. Based on the above-mentioned fiber optic ring assembly, its special feature is that it includes the following steps:

[0027] Step 1: Install the fiber optic ring into the fiber optic ring frame;

[0028] Step 2: Install the cover plate on the fiber optic ring frame and seal the fiber optic ring shell, completely sealing the connection points except for the channel. Then, inject flexible absorbent material into the fiber optic ring shell through the channel, allowing the material to overflow the entire fiber optic ring, and wait for the material to cure. Alternatively, inject flexible absorbent material into the fiber optic ring shell through the annular opening of the fiber optic ring frame, allowing the material to overflow the entire fiber optic ring, and wait for the material to cure. Then, install the cover plate on the fiber optic ring frame and seal the fiber optic ring shell, completely sealing the connection points except for the channel.

[0029] Step 3: Seal the passage completely.

[0030] Furthermore, in step 2, the fiber optic ring shell is sealed, and the connection is completely sealed except for the channel. Specifically, the connection between the cover plate and the fiber optic ring skeleton is welded, and the connection between the cover plate and the fiber optic ring skeleton is completely sealed except for the channel.

[0031] Step 3 specifically involves welding the fiber optic ring outer shell to each metal sleeve to completely seal the channel.

[0032] Step 1 is as follows:

[0033] Step 1.1: Place the fiber optic ring into the fiber optic ring housing, estimate the position of each pigtail extending out of the channel and mark it accordingly;

[0034] Step 1.2: Remove the fiber ring, peel off the fiber coating of a section on each pigtail according to the markings, and put a metal sleeve on the outside of the fiber cladding at the point where the fiber coating has been removed.

[0035] Step 1.3: Seal the cladding of each stripped fiber with the corresponding metal sleeve by welding, ensuring that there are no gaps at each weld and that each weld covers all the fiber cladding at the stripped fiber.

[0036] Step 1.4: Place the fiber optic ring into the fiber optic ring skeleton, and extend each pigtail out of the channel at a preset angle.

[0037] Further, in step 1.2, the fiber coating layer of a section on each pigtail is stripped according to the mark, specifically: the fiber coating layer of a section before and after the mark position on each pigtail is stripped.

[0038] The welding method used in step 1.3 is glass welding;

[0039] In step 2, a flexible water-absorbing material is injected into the outer shell of the optical fiber ring so that the flexible water-absorbing material covers the entire optical fiber ring. Specifically, the flexible water-absorbing material is injected into the outer shell of the optical fiber ring so that the flexible water-absorbing material covers the entire optical fiber ring and fills 75%-90% of all the space in the cavity of the optical fiber ring outer shell except for the space occupied by the optical fiber ring.

[0040] The welding method used in step 3 is metal welding.

[0041] Compared with the prior art, the present invention has the following beneficial technical effects:

[0042] 1. The fiber optic ring assembly of the present invention has a flexible water-absorbing material inside the fiber optic ring shell, which has stronger airtightness and vibration resistance. On this basis, the fiber cladding of the pigtail is sealed to the metal sleeve through a glass welding layer, and the metal sleeve is sealed to the fiber optic ring shell through a metal welding layer. The welding seal has a stronger ability to isolate liquids. Thus, the fiber optic ring assembly of the present invention can efficiently and reliably seal and isolate the fiber optic ring from the outside world, ensuring the long-term stability of the fiber optic ring, ensuring the long-term stability of the fiber optic ring assembly, and ensuring the high-precision performance of the fiber optic gyroscope.

[0043] 2. The sealing process method for improving the long-term stability of the fiber optic ring assembly of the present invention is simple to operate and easy to implement. It can significantly enhance the sealing performance of the fiber optic ring assembly, thereby ensuring the long-term stability of the fiber optic ring assembly and thus ensuring the accuracy performance of the fiber optic gyroscope. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the fiber optic ring housing in an embodiment of the fiber optic ring assembly of the present invention;

[0045] Figure 2 This is a schematic diagram of the sealing at the channel in an embodiment of an optical fiber ring assembly according to the present invention.

[0046] The annotations in the attached figures are explained as follows:

[0047] 1-Fiber optic ring outer shell, 11-Fiber optic ring skeleton, 12-Cover plate, 13-Channel, 2-Pigtail, 21-Fiber optic coating, 22-Fiber optic cladding, 3-Metal sleeve, 4-Flexible absorbent material, 5-First welding layer, 6-Second welding layer. Detailed Implementation

[0048] To make the objectives, advantages and features of the present invention clearer, the following describes in further detail, with reference to the accompanying drawings and specific embodiments, an optical fiber ring assembly and a sealing process method for improving its long-term stability.

[0049] Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0050] In the description of this invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0051] like Figure 1 and Figure 2 As shown, an optical fiber ring assembly includes an optical fiber ring and a metal optical fiber ring housing 1. The optical fiber ring housing 1 serves to isolate and protect the optical fiber ring and the carrying circuit structure. The optical fiber ring housing 1 includes an optical fiber ring skeleton 11 and a cover plate 12. The cover plate 12 is installed at the annular opening of the optical fiber ring skeleton 11. The optical fiber ring is installed in the cavity formed by the optical fiber ring skeleton 11 and the cover plate 12. The connection between the cover plate 12 and the optical fiber ring skeleton 11 is sealed by welding. A channel 13 is formed between the optical fiber ring skeleton 11 and the cover plate 12, which connects the cavity to the outside. The optical fiber ring has a pigtail 2, which is led out from the channel 13.

[0052] In other embodiments, the number of pigtails 2 in the fiber optic ring can also be 2, 3, or 4, etc.

[0053] like Figure 2 As shown, the cavity of the fiber optic ring housing 1, excluding the space occupied by the fiber optic ring, is filled with a flexible absorbent material 4, which fills 80% of the cavity excluding the space occupied by the fiber optic ring. When the flexible absorbent material 4 is injected into the fiber optic ring housing 1 through the channel 13, it gradually spreads across the entire fiber optic ring, absorbing moisture from its surface. Afterward, the flexible absorbent material 4 fills 80% of the cavity excluding the space occupied by the fiber optic ring, gradually expelling air from the fiber optic ring housing 1 through the channel 13. This ensures the airtightness of the fiber optic ring. The flexible absorbent material 4 then cures, further ensuring the spatial stability of the fiber optic ring and improving the vibration resistance of the fiber optic ring assembly. The flexible absorbent material 4 is polyethylene resin. In other embodiments, it can be other materials with water absorption, low expansion rate, and curability.

[0054] In other embodiments, a flexible absorbent material 4 can be provided to fill 75%-90% of the cavity of the fiber optic ring housing 1, excluding the space occupied by the fiber optic ring. However, the flexible absorbent material 4 needs to cover the entire fiber optic ring to ensure airtightness. For example, the flexible absorbent material 4 can fill 75%, 82%, 85%, 88%, or 90% of the cavity of the fiber optic ring housing 1, excluding the space occupied by the fiber optic ring. In other embodiments, the fiber optic ring housing 1 is also provided with an exhaust hole for venting air from the cavity of the fiber optic ring housing 1. A sealing element is installed inside the exhaust hole, and the connection between the sealing element and the exhaust hole is sealed by welding.

[0055] like Figure 2 As shown, a section of the fiber coating 21 on the pigtail 2 is stripped. A metal sleeve 3 is fitted over the outer side of the fiber cladding 22 where the fiber coating 21 is stripped. The inner circumference of the metal sleeve 3 and the outer circumference of the fiber cladding 22 where the fiber coating 21 is stripped are sealed together by a first welding layer 5. Specifically, the first welding layer 5 is a glass welding layer. The material of the fiber cladding 22 is SiO2. When it is welded with metal, metal ions diffuse into the glass, inducing glass crystallization and forming a tight bonding layer. Glass welding is suitable for most metals and alloys. The specific glass welding temperature and welding method are appropriately selected according to the material of the metal sleeve being welded. The metal sleeve 3 is inserted into the channel 13, and both ends of the metal sleeve 3 extend from both ends of the channel 13. The outer circumference of the metal sleeve 3 and the inner circumference of the channel 13 are sealed together by a second welding layer 6. Specifically, the second welding layer 6 is a metal welding layer. Since the metal sleeve 3 and the fiber optic ring shell 1 are made of different materials, and the channel 13 of different fiber optic ring assemblies has different dimensions, different welding methods can be selected based on practical operability when welding the metal sleeve 3 and the fiber optic ring shell 1.

[0056] It should be noted that in other embodiments, when there are multiple pigtails 2, a section of the optical fiber coating 21 is stripped from each pigtail 2, and a metal sleeve 3 is fitted on the outer side of the optical fiber cladding 22 where the optical fiber coating 21 is stripped from each pigtail 2. The inner circumference of each metal sleeve 3 is sealed to the outer circumference of the corresponding optical fiber cladding 22 through a first welding layer 5. All metal sleeves 3 are inserted into the channel 13, and each metal sleeve 3 is sealed to the optical fiber ring shell 1 through a second welding layer 6. There are gaps between the multiple metal sleeves 3.

[0057] The length of the metal sleeve 3 is set according to the wall thickness of the fiber ring shell 1 at the channel 13 position. The metal sleeve 3 completely covers the fiber cladding 22 where the fiber coating 21 is stripped. The wall thickness of the fiber ring shell 1 at the channel 13 position is 1mm, the length of the metal sleeve 3 is 3mm, and the length of the fiber coating 21 stripped on the pigtail 2 is 3mm.

[0058] In other embodiments, the wall thickness of the fiber optic ring housing 1 can be set according to the actual situation of the product; the length of the metal sleeve 3 can be set according to actual needs. Generally, the length of the metal sleeve 3 is set to be at least 1.5 times the wall thickness of the fiber optic ring housing 1 at the channel 13 position, and the length of the metal sleeve 3 is greater than or equal to the length of the fiber coating layer 21 stripped.

[0059] The inner diameter of the metal sleeve 3 is larger than the outer diameter of the fiber coating layer 21. The inner diameter of the metal sleeve 3 is 0.2 mm. The outer diameter of the metal sleeve 3 can be set according to the size of the channel 13 and the number of pigtails 2. The channel 13 is a square hole with a side length of 1.6 mm. The outer diameter of the metal sleeve 3 is 0.4 mm.

[0060] In other embodiments, the inner diameter of the metal sleeve 3 is set according to the outer diameter of the pigtail 2. Generally, the inner diameter of the metal sleeve 3 is set in the range of 0.2mm to 0.4mm, which is relatively easy to weld. If the inner diameter of the metal sleeve 3 is too large, it will be difficult to weld. Generally, the aperture of the channel 13 is set to be at least twice the outer diameter of the metal sleeve 3, which can accommodate multiple pigtails 2 leading out from the channel 13. Generally, the outer diameter of the metal sleeve 3 is set in the range of 0.4mm to 1mm, which is relatively easy to weld when the metal sleeve 3 is welded to the fiber optic ring shell 1. In other embodiments, the cross-sectional shape of the channel 13 can also be circular, rectangular, etc.

[0061] The metal sleeve 3 is made of nickel, which is relatively easy to weld. In other embodiments, the material of the metal sleeve 3 can also be selected according to actual needs.

[0062] The central axis of the metal sleeve 3 coincides with the central axis of the channel 13. In other embodiments, the angle between the central axis of the metal sleeve 3 and the central axis of the channel 13 should be determined according to the actual situation. Generally, the angle between the central axis of the metal sleeve 3 and the central axis of the channel 13 is not greater than 5°. Within this range, it is easier to weld the metal sleeve 3 to the fiber optic ring shell 1. If the angle between the central axis of the metal sleeve 3 and the central axis of the channel 13 is too large, it is easy to cause loosening and unstable welding.

[0063] Compared with existing technologies, the fiber optic ring assembly proposed in this invention incorporates a flexible absorbent material 4 within the fiber optic ring shell 1, resulting in enhanced airtightness and vibration resistance. Furthermore, the welded seal provides stronger liquid isolation, resulting in a more robust weld. Both glass and metal welding processes can withstand higher temperatures and maintain sealing performance even in extreme environments, thus better ensuring the long-term stability of the fiber optic ring and consequently, the fiber optic ring assembly exhibits excellent long-term stability. Currently, a wide variety of low-expansion-rate flexible absorbent materials are available and widely used. Glass and metal welding processes are highly mature, cost-effective, and reliable.

[0064] A sealing process method for improving the long-term stability of an optical fiber ring assembly, based on the aforementioned optical fiber ring assembly, includes the following steps:

[0065] Step 1: Install the fiber optic ring into the fiber optic ring frame 11 of the fiber optic ring housing 1:

[0066] Step 1.1: Place the fiber optic ring into the fiber optic ring skeleton 11, estimate the position of the fiber optic pigtail 2 extending out of the channel 13 and mark it.

[0067] Step 1.2: Remove the fiber ring, peel off the fiber coating 21 for a total of 3 mm before and after the marked position on the pigtail 2 to expose the fiber cladding 22, and then put a metal sleeve 3 on the outside of the fiber cladding 22 where the fiber coating 21 was peeled off.

[0068] Step 1.3: Seal the fiber cladding 22 at the point where the fiber coating 21 has been removed to the metal sleeve 3 by glass welding, ensuring that there are no gaps at the weld and that the weld covers all the fiber cladding 22 at the point where the fiber coating 21 has been removed.

[0069] Step 1.4: Place the fiber optic ring into the fiber optic ring frame 11, and extend the pigtail 2 out of the channel 13 at a preset angle;

[0070] Step 2: Install the cover plate 12 on the fiber optic ring frame 11 and weld the connection between the cover plate 12 and the fiber optic ring frame 11. Seal the connection between the cover plate 12 and the fiber optic ring frame 11 completely except for the channel 13. Then inject the flexible water-absorbing material 4 into the fiber optic ring shell 1 through the channel 13, so that the flexible water-absorbing material 4 overflows the entire fiber optic ring and fills 80% of the cavity of the fiber optic ring shell 1 except for the space occupied by the fiber optic ring. Wait for the flexible water-absorbing material 4 to cure.

[0071] Step 3: Seal the fiber optic ring outer shell 1 and the metal sleeve 3 by metal welding to completely seal the channel 13.

[0072] In other embodiments, the number of pigtails 2 in the fiber optic ring can be 2, 3, 4, etc. Therefore, the above steps need to be adjusted accordingly. Specifically: in step 1.1, it is necessary to estimate the position of each pigtail 2 extending out of the channel 13 and mark each pigtail 2; in step 1.2, it is necessary to peel off the fiber coating layer 21 of 3 mm before and after the marked position on each pigtail 2, and put a metal sleeve 3 on the outside of the fiber cladding 22 at each point where the fiber coating layer 21 has been peeled off; in step 1.3, it is necessary to seal the fiber cladding 22 at each point where the fiber coating layer 21 has been peeled off to the corresponding metal sleeve 3 by glass welding, ensuring that there are no gaps at each weld and that each weld covers all the fiber cladding 22 at the corresponding point where the fiber coating layer 21 has been peeled off; in step 1.4, it is necessary to extend each pigtail 2 out of the channel 13 at a preset angle; in step 3, it is necessary to seal the fiber optic ring shell 1 to all the metal sleeves 3 by metal welding, so that the channel 13 is completely sealed.

[0073] In other embodiments, step 2 can be set as follows: first, inject flexible water-absorbing material 4 into the fiber optic ring shell 1 through the annular opening of the fiber optic ring skeleton 11, so that the flexible water-absorbing material 4 overflows the entire fiber optic ring and fills 75%-90% of all spaces in the cavity of the fiber optic ring shell 1 except for the space occupied by the fiber optic ring, and wait for the flexible water-absorbing material 4 to cure, then install the cover plate 12 at the annular opening of the fiber optic ring skeleton 11, and then weld the connection between the cover plate 12 and the fiber optic ring skeleton 11, completely sealing the connection between the cover plate 12 and the fiber optic ring skeleton 11 except for the channel 13.

[0074] The sealing process method of the present invention for improving the long-term stability of fiber optic ring assembly achieves overall sealing of the fiber optic ring and the fiber optic ring shell 1, which can significantly enhance the sealing performance of the fiber optic ring assembly, ensure the long-term stability of the fiber optic ring assembly, and thus significantly improve the long-term stability of the fiber optic gyroscope.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the specific technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. An optical fiber ring assembly, comprising an optical fiber ring housing (1) and an optical fiber ring, wherein the optical fiber ring housing (1) comprises an optical fiber ring skeleton (11) and a cover plate (12), the optical fiber ring skeleton (11) and the cover plate (12) being sealed together, and the optical fiber ring being installed within a cavity formed by the optical fiber ring skeleton (11) and the cover plate (12), characterized in that: It also includes a flexible absorbent material (4) covering the optical fiber ring; The flexible absorbent material (4) fills the space in the cavity of the optical fiber ring shell (1) except for the space occupied by the optical fiber ring; The fiber optic ring housing (1) is provided with a channel (13) that connects the cavity of the fiber optic ring housing (1) to the outside. The pigtail (2) of the fiber optic ring is led out from the channel (13), and the number of pigtails (2) is at least one. The channel (13) is sealed.

2. The fiber optic ring assembly according to claim 1, characterized in that: The flexible absorbent material (4) fills 75%-90% of the cavity of the fiber optic ring shell (1) except for the space occupied by the fiber optic ring.

3. The fiber optic ring assembly according to claim 2, characterized in that: The flexible absorbent material (4) is injected into the cavity of the fiber optic ring housing (1) through the channel (13) into the space excluding the space occupied by the fiber optic ring.

4. The fiber optic ring assembly according to claim 1, characterized in that: A section of the fiber coating (21) on the pigtail (2) is stripped off, and a metal sleeve (3) is fitted on the outside of the fiber cladding (22) where the fiber coating (21) is stripped off. The metal sleeve (3) completely covers the fiber cladding (22) where the fiber coating (21) is stripped off. The inner circumference of the metal sleeve (3) and the outer circumference of the fiber cladding (22) where the fiber coating (21) is stripped off are sealed and connected by a first welding layer (5). The metal sleeve (3) is inserted into the channel (13), and the outer periphery of the metal sleeve (3) and the inner periphery of the channel (13) are sealed together by a second welding layer (6).

5. The fiber optic ring assembly according to claim 4, characterized in that: The number of the pigtails (2) is multiple, and the multiple metal sleeves (3) are spaced apart from each other.

6. The fiber optic ring assembly according to claim 4 or 5, characterized in that: The length of the metal sleeve (3) is defined as M, and the length of the stripped fiber coating layer (21) is defined as L, where M≥L; The two ends of the metal sleeve (3) extend from the two ends of the channel (13), and the wall thickness of the fiber optic ring shell (1) at the position of the channel (13) is defined as N, M≥1.5×N; The angle between the central axis of the metal sleeve (3) and the central axis of the channel (13) is in the range of 0° to 5°. The aperture of the channel (13) is defined as D, and the outer diameter of the metal sleeve (3) is defined as d, where D≥2×d; The inner diameter of the metal sleeve (3) ranges from 0.2 mm to 0.4 mm, and the outer diameter of the metal sleeve (3) ranges from 0.4 mm to 1 mm.

7. The fiber optic ring assembly according to claim 4, characterized in that: The first welding layer (5) is a glass welding layer; The second welding layer (6) is a metal welding layer; The metal sleeve (3) is made of nickel; The flexible absorbent material (4) is polyethylene resin; The connection between the fiber optic ring frame (11) and the cover plate (12) is sealed by welding.

8. A sealing process method for improving long-term stability of a fiber loop assembly, based on the fiber loop assembly according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Install the fiber optic ring into the fiber optic ring frame (11); Step 2: Install the cover plate (12) on the fiber optic ring frame (11) and seal the fiber optic ring shell (1) completely, except for the channel (13). Then inject flexible absorbent material (4) into the fiber optic ring shell (1) through the channel (13) so that the flexible absorbent material (4) covers the entire fiber optic ring and wait for the flexible absorbent material (4) to cure. Alternatively, inject flexible absorbent material (4) into the fiber optic ring shell (1) through the annular opening of the fiber optic ring frame (11) so that the flexible absorbent material (4) covers the entire fiber optic ring and wait for the flexible absorbent material (4) to cure. Then install the cover plate (12) on the fiber optic ring frame (11) and seal the fiber optic ring shell (1) completely, except for the channel (13). Step 3: Seal the channel (13) completely.

9. The sealing process method for improving the long-term stability of fiber optic ring assemblies according to claim 8, characterized in that: In step 2, the fiber optic ring shell (1) is sealed, and the connection is completely sealed except for the channel (13). Specifically, the connection between the cover plate (12) and the fiber optic ring skeleton (11) is welded, and the connection between the cover plate (12) and the fiber optic ring skeleton (11) is completely sealed except for the channel (13). Step 3 specifically involves welding the fiber optic ring shell (1) to each metal sleeve (3) to completely seal the channel (13); Step 1 is as follows: Step 1.1: Place the fiber optic ring into the fiber optic ring housing (1), estimate the position of each pigtail (2) of the fiber optic ring extending out of the channel (13) and mark it. Step 1.2: Take out the fiber ring, strip the fiber coating (21) of a section on each pigtail (2) according to the markings, and put a metal sleeve (3) on the outside of the fiber cladding (22) at each stripped fiber coating (21). Step 1.3: Seal the fiber cladding (22) at each stripped fiber coating (21) with the corresponding metal sleeve (3) by welding, ensuring that there are no gaps at each weld and that each weld covers all the fiber cladding (22) at the corresponding stripped fiber coating (21). Step 1.4: Place the fiber optic ring into the fiber optic ring skeleton (11), and each pigtail (2) extends out of the channel (13) at a preset angle.

10. The sealing process method for improving the long-term stability of fiber optic ring assemblies according to claim 9, characterized in that: In step 1.2, the fiber coating layer (21) of a section on each pigtail (2) is stripped according to the mark, specifically: the fiber coating layer (21) of a section before and after the mark position on each pigtail (2) is stripped. The welding method used in step 1.3 is glass welding; In step 2, a flexible water-absorbing material (4) is injected into the fiber optic ring shell (1) so that the flexible water-absorbing material (4) covers the entire fiber optic ring. Specifically, the flexible water-absorbing material (4) is injected into the fiber optic ring shell (1) so that the flexible water-absorbing material (4) covers the entire fiber optic ring and fills 75%-90% of the space in the cavity of the fiber optic ring shell (1) except for the space occupied by the fiber optic ring. The welding method used in step 3 is metal welding.

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