Optical fiber ring tail fiber merging processing method

Abstract

The invention relates to an optical fiber ring tail fiber merging processing method, which aims at an optical fiber ring wound by a polarization maintaining optical fiber, comprises the following steps of: identifying and distinguishing clockwise and anticlockwise tail fibers, cleaning and pre-processing, brushing glue, coiling to a symmetrical position of a boss according to preset parameters, respectively carrying out S-shaped and U-shaped bending and fixing, then attaching and merging fibers in parallel, and extending and fixing to the upper surface of the optical fiber ring. The whole process is matched with tension control and double detection correction. According to the invention, the length of the tail fiber is highly consistent with the stress distribution, the symmetry of the optical fiber ring is ensured, the damage of the optical fiber is avoided, the fiber combining stability and the process standardization degree are improved, the polarization cross coupling and phase error are effectively reduced, the measurement precision of the fiber-optic gyroscope is obviously improved, and the requirements of aviation, navigation and other high-precision inertial navigation are met.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope manufacturing technology, and more specifically to a method for processing fiber optic loop tails into parallel fibers. Background Technology

[0002] As an angular rate measuring instrument based on the Sagnac effect, the fiber optic gyroscope has become a core component of modern inertial navigation systems due to its advantages such as high precision, simple structure, small size, and large dynamic range. The fiber optic loop, as the core sensitive component of the fiber optic gyroscope, is made of polarization-maintaining fiber. The consistency of its pigtail length and the symmetry of stress distribution directly affect the measurement accuracy of the fiber optic gyroscope.

[0003] After the fiber optic loop is completed, the two pigtails have two different fiber exit directions, clockwise and counterclockwise. In order to form a complete Sagnac interferometer, the two pigtails need to be fused with the Y-waveguide pigtail. The fiber fusion process before fusion must ensure that the length of the two pigtails is consistent with the stress distribution. Otherwise, it will cause problems such as polarization cross-coupling and phase error, resulting in a decrease in gyroscope accuracy.

[0004] Existing pigtail parallel processing technology has significant shortcomings: the control of parameters such as the radius and number of turns of the pigtail coil is not precise, which can easily lead to excessive length difference; the bending process lacks standardized design, which may cause fiber damage or stress concentration; the parallel spacing accuracy is insufficient and the reinforcement measures are not perfect, resulting in poor bonding stability; at the same time, there is a lack of a complete cleaning, tension control and detection and correction mechanism, and problems such as pigtail surface contamination, uneven tension and excessive stress occur frequently, which ultimately destroy the symmetry of the fiber ring and cannot meet the requirements of high-precision navigation. Summary of the Invention

[0005] To address the aforementioned issues, there is an urgent need for a fiber optic loop pigtail paralleling process that can precisely control the parameters of the entire process, including pigtail coiling, bending, paralleling, and fixing, while also possessing a complete cleaning, tension control, and detection and correction mechanism. This would enable the two pigtails to achieve a high degree of consistency in length and stress distribution, ensuring the symmetry and stability of the fiber optic loop, thereby resolving the aforementioned technical pain points in existing technologies. To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for processing fiber optic loop pigtails, wherein the fiber loop is formed by winding polarization-maintaining fiber, the polarization axis of the polarization-maintaining fiber being parallel to the fiber winding axis, and the method includes the following steps: Step 1: Based on the fiber winding trajectory and the polarization axis direction of the polarization-maintaining fiber, identify and distinguish the two pigtails after the fiber winding is completed. One is defined as a clockwise pigtail, which extends out along the clockwise winding direction of the fiber loop; the other is defined as a counterclockwise pigtail, which extends out along the counterclockwise winding direction of the fiber loop. Step 2: Apply adhesive evenly to the clockwise side of the fiber optic ring and coil it clockwise until it reaches the symmetrical position of the main boss of the fiber optic ring; apply adhesive evenly to the counterclockwise side of the fiber optic ring and coil it counterclockwise until it reaches the symmetrical position of the same main boss. The starting point of the coiling of the two pigtails is equidistant from the edge of the boss, and the pigtails are in close contact with the surface of the ring during the coiling process. Step 3: Bend the clockwise pigtail in an "S" shape in the pre-set bending area on the side of the optical fiber ring and fix it with glue, so that its fiber outlet direction changes to counterclockwise and the pigtail is not twisted after bending. The counterclockwise pigtail is bent into a "U" shape in the bending area corresponding to the side of the optical fiber ring and fixed with glue, keeping the fiber exit direction unchanged after bending. Step 4: After the two pigtails processed in Step 3, attach them together in parallel along the length of the fiber-joining area on the side of the ring body, and keep the fiber-joining section perpendicular to the axis of the ring body.

[0006] In the preferred embodiment, step five is also included: applying adhesive evenly along the side of the ring to extend the two pigtails after they were combined in step four and fixing them to the preset fixing area on the upper surface of the fiber optic ring. The fixing path is parallel to the edge of the ring, the fixing length is 10~15mm, and the adhesive layer covers more than 2 / 3 of the circumference of the pigtails without any air bubbles remaining.

[0007] In the preferred embodiment, in step two, the radius of the adhesive coating is controlled at 30~40mm, the number of coils is 1~2, the number of coils for the clockwise and counterclockwise pigtails is the same, the spacing between adjacent pigtails is uniform at 0.3~0.5mm, and the coiling trajectories of the two pigtails are centrally symmetrical.

[0008] In the preferred embodiment, in step three, the radius of curvature of the "U"-shaped bend is 4~5mm, the bending angle is 175°~185°, the optical fiber at the bend has no creases and the sheath is undamaged, the tangent direction of the bend is perpendicular to the side of the ring, and the straight extension length of the pigtail after bending is 5~8mm.

[0009] In the preferred embodiment, in step three, the “S”-shaped bend consists of two symmetrical arc segments, each with a radius of curvature of 5-6 mm, the difference between the radii of curvature of the two arc segments not exceeding 1 mm, and the total length of the bend is 30-40 mm. After bending, the extension direction of the clockwise tail fiber is parallel to the extension direction of the counterclockwise tail fiber, the parallelism deviation does not exceed ±0.05 mm, and the polarization axis direction remains unchanged.

[0010] In the preferred embodiment, the adhesive used in steps two and three is a low-shrinkage UV-curable adhesive, which does not contain volatile organic compounds and has a volume shrinkage rate of no more than 2% during curing. The adhesive thickness is uniformly controlled at 0.1~0.3mm, and a wavelength of 365~385nm and a power of 50~80mW / cm are used. 2 The adhesive layer is cured under ultraviolet light for 30~60s. After curing, the Shore hardness of the adhesive layer is D50~D60, and the bonding strength with the polarization-maintaining fiber sheath is not less than 1.5MPa.

[0011] In the preferred embodiment, in step four, when the two pigtails are bonded together, the spacing between them is controlled between 0.1 and 0.2 mm, and the spacing fluctuation along the length of the pigtails does not exceed ±0.03 mm. The length of the bonded section is not less than 15 mm. The bonded section is reinforced by intermittent glue application, with a glue application spacing of 3 to 5 mm and a glue application amount of 0.01 to 0.03 ml per application. After glue application, the section is cured again by ultraviolet light for 20 to 30 seconds.

[0012] In a preferred embodiment, before step two, a cleaning process is included for the two pigtails: 8.1 Use anhydrous ethanol with a purity of ≥99.7% to wipe the 5-8cm section of the pigtail fiber in one direction, and do not rub back and forth; 8.2 After wiping, place the pigtail in a clean, dust-free space with a temperature of 20-25℃ and a humidity of 40%-60% to air dry naturally for 1-2 minutes, ensuring that the pigtail surface is free of oil, fiber residue, and sheath damage.

[0013] In the preferred embodiment, in step two, during the glue application and winding process, a tension controller with an accuracy of ±0.02N is used to control the winding tension of the pigtail in real time, so that the tension is stabilized between 0.5 and 1.0N. The difference in winding tension between the clockwise and counterclockwise pigtails shall not exceed 0.1N. When the tension fluctuation exceeds ±0.05N, the equipment will automatically pause winding and restart winding after adjusting to the set range.

[0014] In the preferred embodiment, after step three is completed, the two pigtails undergo dual testing and calibration: 10.1 Stress testing: Distributed stress testing is performed using an optical fiber stress tester with a resolution of 0.1MPa to ensure that the stress value after the pigtail is bent and fixed is controlled within the range of 5~10MPa. If it exceeds the range, the adhesive layer is disassembled and bent and fixed again. 10.2 Length Consistency Inspection: A laser rangefinder with a measurement accuracy of ±0.01mm is used to measure the length of the two pigtails from the symmetrical position of the protrusion to the starting point of the fiber coupling, ensuring that the length difference does not exceed 0.1mm; if the length difference exceeds the standard, the number of coils is adjusted first, with the adjustment range not exceeding 1 turn; if the number of coils adjustment cannot meet the requirements, the bending angle is finely adjusted, with the adjustment range not exceeding 5°, until the length consistency requirement is met.

[0015] A method for processing optical fiber loop pigtails has the following beneficial effects, including but not limited to: 1. By defining the pigtail winding parameters, standardizing the bending process, and controlling the tension in real time, the length difference between the two pigtails is controlled within 0.1mm, and the stress is stabilized within a reasonable range, which significantly improves the consistency of the fiber ring structure and optical path, and suppresses polarization cross-coupling and phase error from the source. 2. Strictly limit the curvature radius, angle and other parameters of the pigtail bending, and use precise cleaning process to avoid fiber creases, sheath damage and surface contamination, to ensure the stability of the polarization axis of the polarization-maintaining fiber and prevent signal fading; 3. This invention employs low-shrinkage UV-curing adhesive and intermittent adhesive reinforcement technology to improve the bonding strength and uniformity of the fiber segments; the extended fixing design further enhances the pigtail's resistance to vibration and temperature changes, extending its service life. 4. This invention establishes a standardized system for the entire process and a dual detection and correction mechanism to reduce human error, promptly correct length deviations or stress exceeding limits, and ensure that the processing effect meets high precision requirements. 5. The regularized parallel fiber and extension path of this invention optimizes the optical path assembly compatibility, reduces the impact of non-reciprocity on temperature performance, and ultimately improves the measurement accuracy of fiber optic gyroscope angular rate, adapting to the inertial navigation requirements in complex environments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the optical fiber ring body in an embodiment of the present invention; Figure 2 This is a schematic diagram of the clockwise "S"-shaped bend of the pigtail in step three of this embodiment of the invention; Figure 3 This is a schematic diagram of the counterclockwise U-shaped bend of the pigtail in step three of this embodiment of the invention; Figure 4 This is a schematic diagram of the two pigtails after being joined together in step four of this embodiment of the invention. Detailed Implementation

[0017] Example 1 (Basic Standard Example): This embodiment targets a 50mm diameter fiber ring made of panda-shaped polarization-maintaining fiber, where the polarization axis of the polarization-maintaining fiber is parallel to the fiber winding axis. The specific processing steps are as follows: S1, Reference Figure 1 Based on the fiber winding trajectory and polarization axis marking of the polarization-maintaining fiber, the clockwise pigtail extending along the clockwise winding direction of the fiber ring and the counterclockwise pigtail extending along the counterclockwise winding direction are identified, and corresponding markings are made to avoid confusion. S2. Soak a lint-free cloth in 99.8% pure anhydrous ethanol for 5 seconds, then wipe the two pigtails 6cm from the fiber exit end in one direction to avoid back-and-forth friction. After wiping, place the pigtails in a Class 100 cleanroom with a temperature of 22°C and a humidity of 50% to air dry naturally for 1.5 minutes. Visually inspect the pigtails to confirm that there is no oil, no fiber residue, and no damage to the sheath. S3. Select a tension controller with an accuracy of ±0.02N, and rotate the fiber clockwise along... Figure 1 The fiber optic loop shown is uniformly coated with adhesive and coiled clockwise around its outer side, with a coiling radius of 35mm, 2 coils, and a 0.4mm spacing between adjacent coils. Simultaneously, a counter-clockwise pigtail is coated with adhesive and coiled counter-clockwise around the outer side of the loop, with the same coiling radius, number of coils, and spacing as the clockwise pigtail. The starting points for both pigtails are... Figure 1 The distance between the edges of the main boss is 2mm. During the winding process, the tail fiber is kept in close contact with the surface of the ring, the tension is kept stable at 0.8N, and the tension difference between the two tail fibers is controlled within 0.08N. When the tension fluctuation exceeds ±0.05N, the equipment automatically stops winding, adjusts to the set range, and restarts. Finally, both tail fibers are wound to the symmetrical position of the main boss, and the winding trajectory is centrally symmetrical. S4, in Figure 1 The pre-defined bending area on the side of the fiber optic ring shown is used to bend the clockwise pigtail. Figure 2 The "S"-shaped bend shown consists of two symmetrical arc segments, each with a radius of curvature of 5.5 mm and a difference of 0.05 mm between the two segments. The total length of the bend is 35 mm. After bending, the clockwise fiber exit direction changes to counterclockwise without twisting, while the polarization axis direction remains unchanged. The parallelism deviation with the counterclockwise fiber extension direction is ±0.03 mm. The counterclockwise fiber is then subjected to... Figure 3 The "U"-shaped bend shown has a radius of curvature of 4.5mm and a bending angle of 180°. There are no creases or damage to the sheath at the bend. The tangent direction of the bend is perpendicular to the side of the ring. The straight extension length of the pigtail after bending is 6mm. After bending, low-shrinkage UV-curing adhesive is applied to the bent parts of the two pigtails with a thickness of 0.2mm. S5. The area to which the adhesive was applied was irradiated with ultraviolet light of wavelength 375nm and power 65mW / cm² for 45s. After curing, the Shore hardness of the adhesive layer was D55, and the bonding strength with the polarization-maintaining fiber sheath reached 1.8MPa. S6. After bending and curing, the two pigtails are... Figure 1The fiber-ply regions on the side of the ring shown are bonded parallel to each other along the length direction, and the bonding state is as follows: Figure 4 As shown, the bonding time interval is controlled at 0.15mm, and the spacing fluctuation along the length of the pigtail does not exceed ±0.02mm. The bonding section length is 18mm. After bonding, intermittent glue application is used for reinforcement, with a glue application interval of 4mm and a glue amount of 0.02ml per application. After glue application, UV light with the same parameters is used again for curing for 25s to ensure a firm bond. S7, after the two pigtails are combined, follow the... Figure 4 As shown, the adhesive is applied evenly to the side of the ring, with a thickness of 0.2 mm, extending to the preset fixing area on the upper surface of the fiber optic ring. The fixing path is parallel to the edge of the ring, with a fixing length of 12 mm. The adhesive layer covers 3 / 4 of the circumference of the pigtail. After inspection, no air bubbles are found. The fiber is then cured with ultraviolet light for 40 seconds. S8. Distributed stress testing was performed on the two pigtails using a fiber optic stress tester with a resolution of 0.1 MPa. The stress value of the clockwise pigtail was 7.2 MPa, and the stress value of the counterclockwise pigtail was 7.0 MPa, both of which met the requirements. A laser rangefinder with a measurement accuracy of ±0.01 mm was used to measure the length of the two pigtails from the symmetrical position of the boss to the starting point of the fiber connection. The length difference was 0.08 mm, which met the accuracy requirements and did not require calibration. After processing in this embodiment, the fiber optic loop pigtails have consistent lengths, uniform stress distribution, and good symmetry. After subsequent fusion splicing with the Y-waveguide pigtails, the angular rate measurement accuracy of the fiber optic gyroscope reaches 0.01° / h, meeting the usage requirements in the field of aviation navigation.

[0018] Example 2 (Optimized Adapted Example): This embodiment focuses on a small fiber optic ring with a diameter of 30mm, made of elliptical cladding polarization-maintaining fiber. The specific processing steps are as follows: S1, Reference Figure 1 (Schematic diagram of fiber optic ring) By using the winding record of the fiber optic winding equipment and the polarization axis detection instrument of the polarization-maintaining fiber, the extension direction of the clockwise and counterclockwise pigtails is determined and marked. S2. Soak a clean cloth in 99.7% pure anhydrous ethanol for 8 seconds, and wipe the two pigtails 5cm from the fiber outlet in one direction. After wiping, place the pigtails in a Class 100 cleanroom with a temperature of 20℃ and a humidity of 45% to air dry naturally for 1 minute to confirm that there are no contaminants or damage on the surface of the pigtails. S3. Activate the tension controller, and rotate the fiber clockwise along... Figure 1 The fiber optic loop shown is coiled clockwise with adhesive applied to its outer side, with a coiling radius of 32mm, one coil, and a spacing of 0.3mm between adjacent loops. The counter-clockwise pigtail is simultaneously coiled counter-clockwise along the outer side of the loop, with the same parameters as the clockwise pigtail. The starting points of both pigtails are... Figure 1The distance between the edges of the main boss is 1.5mm, the winding tension is stable at 0.6N, the tension difference does not exceed 0.05N, and finally they are all wound to the symmetrical position of the main boss, and the winding trajectory is centrally symmetrical; S4. Perform clockwise fiber optic adjustments. Figure 2 The "S"-shaped bend shown has two symmetrical arc segments with a radius of curvature of 5.2 mm each, differing by 0.03 mm. The total length of the bend is 32 mm. After bending, the fiber output direction turns counterclockwise, without twisting, and the polarization axis direction remains unchanged. The parallelism deviation with the counterclockwise fiber extension direction is ±0.04 mm. The counterclockwise fiber is then subjected to... Figure 3 The "U"-shaped bend shown has a radius of curvature of 4.2mm, a bending angle of 178°, no creases at the bend, and the tangent of the bend is perpendicular to the side of the ring. The straight extension is 5mm long. After bending, a low-shrinkage UV-curing adhesive is applied with a thickness of 0.15mm. S5. After curing, the adhesive layer is irradiated with ultraviolet light at a wavelength of 365nm and a power of 55mW / cm² for 35s, resulting in a Shore hardness of D52 and an adhesion strength of 1.6MPa. S6. Attach the two pigtails parallel to each other in the fiber-joining area, as shown in the attachment state. Figure 4 As shown, the spacing is controlled at 0.1mm, with a spacing fluctuation not exceeding ±0.02mm, and the bonding section length is 15mm; intermittent adhesive application is used for reinforcement, with an adhesive application spacing of 3mm, each application amount of 0.01ml, and UV curing for 20s after application; S7, the tail fiber edge after fiber bonding Figure 4 As shown, the adhesive is applied to the side of the ring and extends to the upper surface of the fiber optic ring. The fixing path is parallel to the edge of the ring and the fixing length is 10mm. The adhesive layer covers 2 / 3 of the circumference of the pigtail, with no air bubbles remaining. It is cured with ultraviolet light for 30 seconds. S8. The stress test results show that the stress values ​​of the two pigtails are 6.5MPa and 6.3MPa, respectively, which meet the requirements; the length consistency test shows that the length difference between the two pigtails is 0.05mm, which meets the accuracy requirements and does not require correction. This embodiment is adapted to the structural characteristics of small fiber optic rings. By adjusting the number of coils and bending parameters, it ensures the consistency of the pigtail while adapting to the compact space assembly requirements. The processed fiber optic ring is used in small inertial navigation equipment, and the fiber optic gyroscope measurement accuracy reaches 0.02° / h, meeting the usage requirements of small marine navigation modules.

[0019] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention; no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for processing optical fiber loop pigtails, characterized in that, The fiber loop is made of polarization-maintaining fiber, and the polarization axis of the polarization-maintaining fiber is parallel to the fiber winding axis. The fiber loop pigtail processing method includes the following steps: Step 1: Based on the fiber winding trajectory and the polarization axis direction of the polarization-maintaining fiber, identify and distinguish the two pigtails after the fiber winding is completed. One is defined as a clockwise pigtail, which extends out along the clockwise winding direction of the fiber loop; the other is defined as a counterclockwise pigtail, which extends out along the counterclockwise winding direction of the fiber loop. Step 2: Apply adhesive evenly to the clockwise side of the fiber optic ring and coil it clockwise until it reaches the symmetrical position of the main boss of the fiber optic ring; apply adhesive evenly to the counterclockwise side of the fiber optic ring and coil it counterclockwise until it reaches the symmetrical position of the same main boss. The starting point of the coiling of the two pigtails is equidistant from the edge of the boss, and the pigtails are in close contact with the surface of the ring during the coiling process. Step 3: Bend the clockwise pigtail in an "S" shape in the pre-set bending area on the side of the optical fiber ring and fix it with glue, so that its fiber outlet direction changes to counterclockwise and the pigtail is not twisted after bending. The counterclockwise pigtail is bent into a "U" shape in the bending area corresponding to the side of the optical fiber ring and fixed with glue, while keeping the fiber exit direction unchanged after bending. Step 4: After the two pigtails processed in Step 3, attach them together in parallel along the length of the fiber-joining area on the side of the ring body, and keep the fiber-joining section perpendicular to the axis of the ring body.

2. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, The process also includes step five: applying adhesive evenly along the side of the ring to extend the two pigtails that were spliced ​​in step four and fixing them to the preset fixing area on the upper surface of the fiber optic ring. The fixing path is parallel to the edge of the ring, and the fixing length is 10-15mm. The adhesive layer covers more than 2 / 3 of the circumference of the pigtails and there are no air bubbles.

3. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, In step two, the radius of the adhesive coating is controlled at 30~40mm, and the number of coils is 1~2. The number of coils for the clockwise and counterclockwise pigtails is the same. The spacing between adjacent pigtails is uniform at 0.3~0.5mm, and the coiling trajectories of the two pigtails are centrally symmetrical.

4. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, In step three, the radius of curvature of the "U"-shaped bend is 4~5mm, the bending angle is 175°~185°, the optical fiber has no creases and the sheath is undamaged at the bend, the tangent direction of the bend is perpendicular to the side of the ring, and the straight extension length of the pigtail after bending is 5~8mm.

5. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, In step three, the "S"-shaped bend consists of two symmetrical arc segments, each with a radius of curvature of 5-6 mm, and the difference between the radii of curvature of the two arc segments does not exceed 1 mm. The total length of the bend is 30-40 mm. After bending, the extension direction of the clockwise tail fiber is parallel to the extension direction of the counterclockwise tail fiber, with a parallelism deviation of no more than ±0.05 mm, and the polarization axis direction remains unchanged.

6. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, The adhesive used in steps two and three is a low-shrinkage UV-curable adhesive. This adhesive does not contain volatile organic compounds, and its volume shrinkage during curing does not exceed 2%. The adhesive thickness is uniformly controlled at 0.1~0.3mm, using a wavelength of 365~385nm and a power of 50~80mW / cm². 2 The adhesive layer is cured under ultraviolet light for 30~60s. After curing, the Shore hardness of the adhesive layer is D50~D60, and the bonding strength with the polarization-maintaining fiber sheath is not less than 1.5MPa.

7. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, In step four, when the two pigtails are bonded together, the spacing between them should be controlled between 0.1 and 0.2 mm, and the spacing along the length of the pigtails should not fluctuate by more than ±0.03 mm. The length of the bonded section should not be less than 15 mm. The bonded section should be reinforced with intermittent glue application, with a glue application interval of 3 to 5 mm and a glue application amount of 0.01 to 0.03 ml per application. After application, the section should be cured again by UV irradiation for 20 to 30 seconds.

8. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, Before step two, a cleaning process is also included for the two pigtails: 8.1 Use anhydrous ethanol with a purity of ≥99.7% to wipe the 5-8cm section of the pigtail fiber in one direction, and do not rub back and forth; 8.2 After wiping, place the pigtail in a clean, dust-free space with a temperature of 20-25℃ and a humidity of 40%-60% to air dry naturally for 1-2 minutes, ensuring that the pigtail surface is free of oil, fiber residue, and sheath damage.

9. The fiber optic loop pigtail fiber parallelization method according to claim 1, characterized in that, In step two, during the glue application and winding process, a tension controller with an accuracy of ±0.02N is used to control the winding tension of the pigtail in real time, so that the tension is stabilized between 0.5 and 1.0N. The difference in winding tension between the clockwise and counterclockwise pigtails shall not exceed 0.1N. When the tension fluctuation exceeds ±0.05N, the equipment will automatically pause winding and restart winding after adjusting to the set range.

10. The fiber optic loop pigtail processing method according to claim 1, characterized in that, after step three is completed, the two pigtails are subjected to dual detection and correction: 10.1 Stress testing: Distributed stress testing is performed using an optical fiber stress tester with a resolution of 0.1MPa to ensure that the stress value after the pigtail is bent and fixed is controlled within the range of 5~10MPa. If it exceeds the range, the adhesive layer is disassembled and bent and fixed again. 10.2 Length Consistency Inspection: A laser rangefinder with a measurement accuracy of ±0.01mm is used to measure the length of the two pigtails from the symmetrical position of the protrusion to the starting point of the fiber coupling, ensuring that the length difference does not exceed 0.1mm; if the length difference exceeds the standard, the number of coils is adjusted first, with the adjustment range not exceeding 1 turn; if the number of coils adjustment cannot meet the requirements, the bending angle is finely adjusted, with the adjustment range not exceeding 5°, until the length consistency requirement is met.

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