A butterfly optical cable with night vision function

Abstract

The present invention relates to the technical field of butterfly optical cables, and particularly to a butterfly optical cable with night vision function. It includes: an optical fiber; two strengthening members symmetrically arranged on both sides of the optical fiber; an inner sheath layer, a night vision function layer, and a transparent outer sheath layer sequentially coated on the outer sides of the optical fiber and the strengthening members; the cross-section of the inner sheath layer is elliptical; the night vision function layer includes a reflective coating coated on the outer side of the inner sheath layer, and a fluorescent fiber mesh structure sleeved on the outer side of the reflective coating; the weaving coverage rate of the fluorescent fiber mesh structure is distributed in a gradient along the circumferential direction of the optical cable to form periodic light-transmitting windows, and the axial projection area of the light-transmitting windows accounts for 25% - 35% of the surface area of the reflective coating. The present invention utilizes the dual effects of the reflective coating and the fluorescent fibers to achieve a triple optical mode of "passive reflection + active light emission + stress response", enabling the optical cable to provide sufficient visibility in low-light or completely dark environments and enhancing the night vision distance.

Description

Technical Field

[0001] The present invention relates to the technical field of butterfly optical cables, and in particular to a butterfly optical cable with night vision function. Background Art

[0002] As an important infrastructure in modern communication, monitoring, security, and various industrial systems, optical cables have been widely used globally. Traditional optical cable designs focus on aspects such as stable signal transmission, anti-interference ability, and tensile strength. The outer sheath of the optical cable usually uses opaque or single-color materials, with a focus on the ability to resist environmental factors (such as temperature, humidity, chemical corrosion). With the progress of technology, optical cables not only carry the task of signal transmission, but their additional functions and intelligent requirements are also increasing. Especially in scenarios such as night operations, emergency repairs, and long-term monitoring of optical cables, the requirements for the visibility and ease of repair of optical cables are getting higher and higher, which has promoted the research and development of optical cables with night vision function.

[0003] Due to its flattened structural design and excellent anti-bending performance, butterfly optical cables are widely used in fiber to the home (FTTH) and short-distance communication fields. To improve the identifiability of optical cables in night or low-light environments. The butterfly optical cable with night vision function, as an innovative optical cable design, its main purpose is to maintain high visibility in low-light or dark environments through special material and structural designs. Initially, the research and development of night vision optical cables mainly focused on improving visibility by coating reflective materials on the outer layer of the optical cable or adding fluorescent markers. The fluorescent markers can emit light under ultraviolet light irradiation and are suitable for night visibility requirements in certain specific environments. The reflective coating increases visibility by reflecting external light sources (such as flashlights, vehicle lights, etc.). Although these two technologies effectively improve the visibility of optical cables, there are still certain limitations. The reflective materials are directly exposed and are easily subject to mechanical wear. When adding fluorescent materials to the sheath material, the phosphor is prone to uneven dispersion during blending with the sheath material, resulting in a decrease in the luminous brightness, and the luminous efficiency of the fluorescent material decreases due to material shielding, resulting in insufficient visibility of the optical cable in complex lighting scenarios.

[0004] The information disclosed in this background art section is only intended to deepen the understanding of the overall background art of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: without affecting the optical fiber signal transmission performance, to provide a butterfly optical cable with night vision function, and through geometric-material collaborative design within the limited structural space of the butterfly optical cable, to achieve efficient optical coupling of the reflective and fluorescent functions, ensure the visibility of the optical cable in low-light or dark environments, and at the same time ensure the mechanical strength and environmental durability of the optical cable.

[0006] The above technical object of the present invention is achieved by the following technical solutions:

[0007] A butterfly optical cable with night vision function, comprising:

[0008] Optical fiber;

[0009] Two strengthening members symmetrically arranged on both sides of the optical fiber;

[0010] An inner sheath layer, a night vision function layer and a transparent outer sheath layer sequentially coated on the outside of the optical fiber and the strengthening member;

[0011] The cross-section of the inner sheath layer is elliptical;

[0012] The night vision function layer includes a reflective coating coated on the outside of the inner sheath layer, and a fluorescent fiber mesh structure sleeved on the outside of the reflective coating; the weaving coverage rate of the fluorescent fiber mesh structure is distributed in a gradient along the circumferential direction of the optical cable, forming a periodic light transmission window, and the axial projection area of the light transmission window accounts for 25% - 35% of the surface area of the reflective coating.

[0013] Furthermore, the fluorescent fiber mesh structure includes aramid fibers arranged longitudinally and stress-responsive fluorescent fibers helically wound on the outside of the aramid fibers at a helix angle of 45° ± 5°. The area density of the light transmission windows in the corresponding areas at both ends of the minor axis of the elliptical cross-section is 20% - 40% higher than that in the corresponding areas at both ends of the major axis. When the stress-responsive fluorescent fiber with a helix angle of 45° is under tension, due to the larger curvature in the minor axis area, the fiber strain and the light intensity response slope are both greater than those in the major axis area, forming an azimuth difference amplification effect of strain-light intensity. The 20 - 40% increase in strength in the major axis direction shortens the visual persistence time, meeting the requirements for rapid visual capture.

[0014] Furthermore, the density gradient change rate dT / dθ of the light transmission windows at both ends of the minor axis ≥ 1.2% / °, and the maximum density area coincides with the focal position of the ellipse. The radius of curvature of the minor axis of the elliptical cross-section is smaller, so that the critical angle in the minor axis area < the major axis area, and total internal reflection is more likely to occur in the minor axis area, guiding more light to the area with a dense light transmission window and improving the reflective effect there.

[0015] Furthermore, the length ratio of the major axis to the minor axis is 1.2 - 1.8:1, and two symmetrical tear openings are provided on both sides of the minor axis. The depth of the tear openings extends to 1 / 3 - 1 / 2 of the thickness of the inner sheath layer. The tear openings in the minor axis area correspond to the window density peak area, forming a preset weak surface and optimizing the tear propagation path.

[0016] Furthermore, the reflective coating is made by coating a glass microsphere reflective coating, the particle size of the glass microspheres is 20 - 50μm, the dry film thickness of the reflective coating is 50% - 70% of the diameter of the glass microspheres, and the exposed height of the glass microspheres accounts for 30% - 50% of their diameter.

[0017] Furthermore, the stress-responsive fluorescent fiber is made by mixing and extruding polyurethane elastomer, ZnS:Cu particles and SrAl2O4 phosphor in a mass ratio of 11:6:3. The stress-responsive fluorescent fiber also includes 0.5~1.2wt% of a silane coupling agent, which is a mixture of γ-aminopropyltriethoxysilane (KH-550) and γ-methacryloxypropyltrimethoxysilane (KH-570) in a mass ratio of 2:1. The stress-responsive fluorescent fiber triggers the fluorescence enhancement effect at a strain threshold of 0.5%, and the luminescence intensity is linearly related to the mechanical stress, realizing real-time stress monitoring.

[0018] Furthermore, the particle size of ZnS:Cu particles is 2~5μm, and the surface is modified by stearic acid, and the amount of modifier added is 0.8%~1.2% of the particle mass; the particle size of SrAl2O4 phosphor is 10~15μm. Under the action of external force, the polyurethane elastomer deforms, and the local stress is amplified by 2~3 times through the hydrogen bond network and transmitted to the ZnS:Cu particles. Under the action of stress, the ZnS:Cu particles undergo lattice distortion, resulting in a change in the bandgap width, which promotes the Cu 2+ As the number of excited state particles increases, the fluorescence intensity increases.

[0019] Furthermore, the spacing between adjacent aramid fibers is 0.5 to 1.2 mm, and the stress-responsive fluorescent fiber is wound in a double helix structure, and the pitch thereof is 3 to 5 times the diameter of the aramid fiber.

[0020] Furthermore, the reinforcement is any one of aramid fiber bundles, phosphated steel wires or FRP rods, and the diameter of the reinforcement is 0.4-0.6 mm; the optical fiber is a bend-insensitive optical fiber, and the minimum bending radius is 5 mm.

[0021] Furthermore, the material of the inner sheath layer is low-smoke halogen-free flame-retardant polyolefin, with a surface roughness Ra≤0.8μm, and the transparent outer sheath layer is a TPU material with a light transmittance of >92% and a refractive index of 1.50~1.52, wherein 0.4~0.6wt% of a UV absorber is added, and the surface roughness Ra≤0.6μm. Specifically, polyether TPU can be used to reduce water absorption.

[0022] Furthermore, the inner surface of the transparent outer sheath layer forms concave patterns corresponding to the pressure of the raised portions of the fluorescent fiber mesh structure, and the depth of the concave patterns is 0.1-0.2 mm.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention can ensure excellent visibility under different lighting conditions by setting a night vision function layer in the butterfly sheath, which can utilize the dual effects of the reflective coating and the fluorescent fiber simultaneously. Specifically, the glass microspheres efficiently reflect external light sources (such as vehicle headlights and flashlights) to enhance the basic visibility. The stress-responsive fluorescent material emits light autonomously under stress or low-light conditions to form an active light source, realizing a triple optical mode of "passive reflection + active light emission + stress response", enabling the optical cable to provide sufficient visibility in low-light or completely dark environments. The two mechanisms complement each other to cover the entire lighting scenario and improve the night vision distance.

[0025] By setting an oval inner sheath and combining the gradient distribution of the light-transmitting windows, the present invention makes the light reflection path concentrate on the outer side with higher visibility requirements, improving the light utilization rate. The high-curvature surface in the short-axis region focuses the reflected light to make the fluorescent fiber emit light intensively projected in the short-axis direction, enhancing the ground-side reflective intensity. The long-axis with low curvature is close to planar reflection, and the light scattering range is wide, supplementing the visibility from side and top views. By setting different densities of light-transmitting windows in different regions, the high-density area in the short-axis direction can compensate for the tensile deformation during bending to ensure the uniform distribution of fluorescence intensity. It not only improves the night vision performance but also can convert the mechanical stress change into a visible optical signal change, realizing the precise correlation between the mechanical state and the optical signal.

[0026] By precisely controlling the coverage rate of the fluorescent fiber, the present invention ensures that 25% - 35% of the direct exposure area is reserved for the reflective coating, thereby allowing a part of the light to pass through the braided layer to the reflective coating, enabling the optical fiber to release light in local areas and providing enhanced visibility in these areas. The design of the light-transmitting window enables the optical cable to form a unique visibility pattern through the local light transmission and reflection mechanism in the dark, significantly improving the positioning and identification ability of the optical cable at night, matching the strain difference between the tensile side and the compression side when the optical cable bends, and directly correlating the change in the light emission intensity with the mechanical state. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0028] Figure 1 It is a schematic structural diagram of a butterfly optical cable with night vision function in the present invention;

[0029] Figure 2 It is a partial structural schematic diagram of the night vision function layer in the present invention;

[0030] Reference numerals: 01, optical fiber; 02, strengthening member; 03, inner sheath layer; 04, night vision function layer; 05, transparent outer sheath layer; 06, reflective coating; 07, fluorescent fiber network structure; 08, light transmission window; 09, tear notch. Detailed implementation manners

[0031] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, a butterfly optical cable with night vision function proposed according to the present invention, its detailed implementation manners, features and effects are described in detail as follows. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] As Figures 1 - 2 shown, a butterfly optical cable with night vision function includes:

[0033] Optical fiber 01; responsible for signal transmission, specifically using bend-insensitive optical fiber (such as G.657.A2), with a minimum bending radius of 5 mm, ensuring the flexibility of cable routing in a narrow space and reducing optical signal attenuation;

[0034] Two strengthening members 02 symmetrically arranged on both sides of the optical fiber 01; the two symmetrically arranged strengthening members 02 are usually composed of aramid fiber bundles, phosphated steel wires or FRP rods, providing structural strength, enabling the optical cable to resist external tensile or compressive forces, and ensuring stable signal transmission inside the optical fiber 01;

[0035] Inner sheath layer 03, night vision function layer 04 and transparent outer sheath layer 05 sequentially coated on the outer sides of the optical fiber 01 and the strengthening member 02;

[0036] The cross-section of the inner sheath layer 03 is elliptical; the main function of the inner sheath is to protect the optical fiber 01 and its signal transmission path from physical damage. Usually, a low-smoke, halogen-free, flame-retardant polyolefin material is selected, which has excellent fire resistance and weather resistance. When the optical cable is bent and installed, the long axis direction should be parallel to the stress surface to maximize the night vision effect.

[0037] The night vision function layer 04 includes a reflective coating 06 coated on the outer side of the inner sheath layer 03 and a fluorescent fiber mesh structure sleeved on the outer side of the reflective coating 06; the weaving coverage rate of the fluorescent fiber mesh structure is distributed in a gradient along the circumferential direction of the optical cable, forming periodic light transmission windows 08. The gradient distribution of the light transmission windows 08 makes the light reflection path concentrate on the outer side with higher visual requirements, improving the light utilization rate. The high-curvature surface in the short-axis region focuses the reflected light to make the fluorescent fibers emit light and project intensively in the short-axis direction, enhancing the ground-side reflective intensity. The low-curvature long-axis is close to plane reflection, and the light scattering range is wide, supplementing the visibility at the side view and top view angles. By setting light transmission windows 08 with different densities in different regions, the high-density area in the short-axis direction can compensate for the tensile deformation during bending, ensuring the uniform distribution of the fluorescence intensity. It not only improves the visual performance at night but also can convert the mechanical stress change into a visible optical signal change, realizing the precise correlation between the mechanical state and the optical signal.

[0038] The axial projection area of the light transmission window 08 accounts for 25% - 35% of the surface area of the reflective coating 06. The area ratio of the light transmission window 08 = (the area of the exposed reflective coating) / (the surface area of the inner sheath - the cross-sectional area of the fluorescent fibers). When the proportion of the light transmission window exceeds the range of 25 - 35%, it will cause the reduction of the reflective intensity in the short-axis region or the delay of the fluorescence response in the long-axis region. The short-axis curvature radius of the elliptical cross-section is smaller, so that the critical angle in the short-axis region < the long-axis region. Total reflection is more likely to occur in the short-axis region, guiding more light to the dense area of the light transmission window 08 and improving the reflective effect at this place.

[0039] It should be explained that in the present invention, "low density" means that the physical opening density of the light transmission window 08 is low, but the chemiluminescence density of the corresponding fluorescent fibers is high. Specifically, the winding density of the fluorescent fibers is controlled by the gradient change of the aramid fiber spacing gradually increasing from the long axis to the short axis, so that the density of the light transmission window 08 in the short-axis region is 40% higher than that in the long-axis region. The high-density windows in the short-axis region concentrate more than 80% of the emitted light intensity, forming a directional emission angle (half-peak width) of about 60°, while the emission angle in the long-axis region spreads to 120°, achieving the effect of "forward enhancement + side light supplement".

[0040]

[0041] The present invention precisely controls the coverage rate of the fluorescent fibers to ensure that 25% - 35% of the direct exposure area of the reflective coating 06 is reserved, thereby allowing a part of the light to pass through the woven layer to the reflective coating 06, enabling the optical fiber 01 to release light in local areas and providing enhanced visibility in these areas. The design of the light transmission window 08 enables the optical cable to form a unique visibility pattern through the local light transmission and reflection mechanism in the dark, significantly improving the positioning and identification ability of the optical cable at night, matching the strain difference between the tensile side and the compression side when the optical cable is bent, and directly correlating the change in the emission intensity with the mechanical state.

[0042] In the present invention, by providing a night vision functional layer 04 in the butterfly sheath, the optical cable can utilize the dual functions of the reflective coating 06 and the fluorescent fibers simultaneously, ensuring excellent visibility under different lighting conditions. The reflective coating 06 reflects external light sources to make the optical cable conspicuous in low-light environments, while the fluorescent fibers emit light by self-luminescence or under ultraviolet excitation, enhancing night visibility; the weaving coverage rate of the fluorescent fiber network structure is distributed in a gradient along the circumferential direction of the optical cable and is uniformly distributed along the axial direction of the optical cable, ensuring the structural balance of the optical cable, so that when the optical cable is bent, stretched or under any external stress, the stress can be evenly distributed, preventing local over-stress concentration and reducing the risk of material damage.

[0043] Specifically, as Figure 2 shown, the fluorescent fiber network structure includes aramid fibers arranged longitudinally and stress-responsive fluorescent fibers helically wound around the outside of the aramid fibers at a helix angle of 45° ± 5°. The area density of the light-transmitting windows 08 in the corresponding regions at both ends of the minor axis of the elliptical cross-section is 40% higher than that in the corresponding regions at both ends of the major axis. When the stress-responsive fluorescent fibers with a helix angle of 45° are under tension, in the minor axis region, due to the larger curvature, both the fiber strain and the light intensity response slope are greater than those in the major axis region, forming an amplified effect of the azimuthal difference in strain-light intensity. The 20% - 40% strength enhancement in the major axis direction of the present invention shortens the persistence of vision time, which better meets the requirements for rapid visual capture.

[0044] To ensure that the fluorescent fibers are always stably in the designed position, the fluorescent fiber network structure is bonded and fixed to the edge of the tear opening 09 through resin glue. The resin bonding provides a reliable fixing effect, avoiding the degradation of the optical cable performance or the failure of the night vision effect caused by displacement or loosening, improving the mechanical stability of the optical cable, and at the same time avoiding the spread of damage to other positions of the fluorescent fiber network structure when the optical cable tears along the tear opening 09.

[0045] In this embodiment, the density gradient change rate dT / dθ of the light-transmitting windows 08 at both ends of the minor axis is ≥ 1.2% / °, and the maximum density region coincides with the position of the ellipse focus. Specifically, dT / dθ = k * E 短 / E 长 , where k is a proportionality coefficient, k = 0.15 - 0.25, E 短 is the bending modulus in the minor axis direction, and E 长 is the bending modulus in the major axis direction. Through a three-point bending test (ASTM D790), the bending modulus in the minor axis direction is measured to be 12.4 GPa, and in the major axis direction is 10.9 GPa, with a ratio of 1.14. The light-transmitting windows in the minor axis region have a high density, and the filled glass microspheres can enhance the local stiffness. The fluorescent fibers in the major axis region are dense, and the aramid fibers can dominate the stiffness, thereby affecting the cross-section stiffness ratio.

[0046] As Figure 1As shown, the ratio of the major axis to the minor axis is 1.2 to 1.8:1. Two symmetric tear openings 09 are provided on both sides of the minor axis. The depth of the tear opening 09 extends to 1 / 3 to 1 / 2 of the thickness of the inner sheath layer 03. The tear opening 09 in the minor axis region corresponds to the density peak region of the light-transmitting window 08, forming a preset weak surface to optimize the tear propagation path.

[0047] As an optimization of this embodiment, the reflective coating 06 is made by coating with glass bead reflective paint, forming a smooth light band, which can efficiently reflect external light sources and provide instant visibility; the wet film thickness is 80 to 100 μm, the coating speed is controlled at 3 to 5 m / min, the particle size of the glass beads is 20 to 50 μm, the dry film thickness of the reflective coating 06 is 50% to 70% of the diameter of the glass beads, and the exposed height of the glass beads accounts for 30% to 50% of their diameter. Ensure that 1 / 3 to 1 / 2 of the volume of the glass beads is exposed to optimize the reflective effect.

[0048] Specifically, acrylic resin is used as the matrix binder, and a silane coupling agent is used to enhance the interfacial bonding force between the glass beads and the acrylic resin. The acrylic resin can enhance the overall durability and environmental change resistance of the reflective coating 06, improving the stability of the reflective effect of the optical cable during long-term use. Especially in extreme environments (such as high temperature, humidity, or ultraviolet radiation, etc.), the coating is not prone to peeling, cracking, or aging. The addition of the silane coupling agent can ensure a strong bonding force between the glass beads and the resin matrix, preventing the beads from falling off or shifting during long-term use. By enhancing the bonding force between the beads and the resin matrix, the reflective coating 06 can maintain its effective reflective performance in various working environments, thereby extending the service life of the optical cable. Specifically, the ratio of the glass beads, acrylic resin, and silane coupling agent is controlled at 60:20:1. By selecting acrylic resin and silane coupling agent and precisely controlling the material ratio, it can ensure that the reflective coating 06 has excellent weather resistance and ultraviolet resistance. In harsh environments such as ultraviolet radiation, rain, and temperature fluctuations, the coating can still maintain a long-term stable reflective effect.

[0049] Before coating, the glass beads are immersed in a KH-550 ethanol solution (concentration 2 to 5 wt%) and ultrasonically treated for 10 to 15 minutes; after drying at 80 to 100 °C, they are mixed with the acrylic resin matrix. Through ultrasonic treatment and chemical impregnation, the surface of the glass beads is optimized, making the application of the coating more uniform and easier to coat. This not only improves the appearance quality of the reflective coating 06 but also enhances the consistency and stability during the production process, ensuring that the night vision effect of each optical cable is uniform.

[0050] The stress-responsive fluorescent fiber is prepared by mixing and extrusion molding polyurethane elastomer, ZnS:Cu particles and SrAl₂O₄ phosphor in a mass ratio of 11:6:3. It can provide continuous lighting effect by self-luminescence in a light-source-free environment. This dual-mode night vision design enables the optical cable to be quickly identified during night construction, maintenance or emergency situations, greatly improving the safety and efficiency of operations.

[0051] The stress-responsive fluorescent fiber also includes 1 wt% of silane coupling agent, and the coupling agent is a mixture of γ-aminopropyltriethoxysilane (KH-550) and γ-methacryloxypropyltrimethoxysilane (KH-570) in a mass ratio of 2:1. The stress-responsive fluorescent fiber triggers the fluorescence enhancement effect at a strain threshold of 0.5%, and the luminescence intensity has a linear relationship with mechanical stress, realizing real-time stress monitoring.

[0052] Among them, the particle size of ZnS:Cu particles is 2 - 5 μm, and the surface is modified with stearic acid, and the addition amount of the modifier is 0.8% - 1.2% of the particle mass; those skilled in the art can use other materials such as ZnS:Mn, and ZnS:Cu particles are used in this application with lower cost. The particle size of SrAl₂O₄ phosphor is 10 - 15 μm. It contains SrAl₂O₄:Eu,Dy fluorescent powder, which has high luminous efficiency and long-term stability. It can generate sufficient brightness under the excitation of ultraviolet light or visible light, ensuring sufficient visibility of the optical cable in low-light environments.

[0053] Under the action of external force, the low curvature in the long-axis region causes more strain energy to be dissipated in the form of bending, and the stress loading of ZnS:Cu particles is insufficient, avoiding false alarms caused by non-destructive micro-strain. When subjected to fracture force, the polyurethane elastomer in the short-axis region is prone to deformation, and the local stress is amplified by 2 - 3 times through the hydrogen bond network and transmitted to the ZnS:Cu particles. The ZnS:Cu particles undergo lattice distortion under stress, resulting in a change in the band gap width, prompting an increase in the number of excited state particles of Cu 2+ and enhancing the fluorescence intensity. It can greatly improve the traceability of the optical cable when it breaks, especially playing a role in emergency repair or fault location.

[0054] The spacing between adjacent aramid fibers is 0.5 - 1.2 mm, and the stress-responsive fluorescent fiber is wound in a double helix structure, and its pitch is 3 - 5 times the diameter of the aramid fiber. The periodic contact points formed by the helical winding can inhibit fiber slippage and reduce the attenuation of the luminescence intensity after 1000 bending cycles. Among them, for every 0.1 mm increase in the spacing between adjacent aramid fibers, the density of the light-transmitting window 08 decreases by 1.8%.

[0055] In order to improve the reinforcement effect, the reinforcement member 02 is any one of aramid fiber bundles, phosphating steel wires or FRP rods, and the diameter of the reinforcement member 02 is 0.4~0.6mm; the optical fiber 01 is a bending-insensitive optical fiber 01, and the minimum bending radius is 5mm.

[0056] The material of the inner sheath layer 03 is low-smoke halogen-free flame-retardant polyolefin, with a surface roughness of Ra≤0.8μm. The transparent outer sheath layer 05 is a TPU material with a transmittance of >92% and a refractive index of 1.50~1.52, to which 0.5wt% of ultraviolet absorber is added, and the surface roughness is Ra≤0.6μm. Specifically, polyether TPU can be used to reduce water absorption. The transparent outer sheath layer 05 not only provides excellent optical transparency, but also effectively resists wear and corrosion from the external environment, extending the service life of the optical cable.

[0057] The inner surface of the transparent outer sheath layer 05 is formed with concave patterns corresponding to the pressure of the raised portions of the fluorescent fiber mesh structure, so as to prevent interlayer slippage from causing misalignment of the light-transmitting window 08 .

[0058] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A butterfly optical cable with night vision function, characterized in that, include: optical fiber; Two reinforcement members symmetrically arranged on both sides of the optical fiber; An inner sheath layer, a night vision function layer and a transparent outer sheath layer are sequentially coated on the outside of the optical fiber and the reinforcement member; The cross section of the inner sheath layer is an ellipse; The night vision functional layer includes a reflective coating coated on the outside of the inner sheath layer, and a fluorescent fiber mesh structure sleeved on the outside of the reflective coating; the weaving coverage of the fluorescent fiber mesh structure is distributed in a gradient along the circumference of the optical cable to form a periodic light-transmitting window, and the axial projection area of ​​the light-transmitting window accounts for 25% to 35% of the surface area of ​​the reflective coating; The fluorescent fiber mesh structure includes aramid fibers arranged in the longitudinal direction and stress-responsive fluorescent fibers spirally wound around the outside of the aramid fibers at a helical angle of 45°±5°. The area density of the light-transmitting windows at the two ends of the short axis of the elliptical cross-section is 20%~40% higher than that at the two ends of the long axis. The density gradient change rate of the light-transmitting windows at the two ends of the short axis dT / dθ≥1.2% / °, and the maximum density area coincides with the focus position of the ellipse.

2. The butterfly optical cable with night vision function according to claim 1, characterized in that The length ratio of the major axis to the minor axis is 1.2-1.8:1, and two symmetrical tearing openings are arranged on both sides of the minor axis. The depth of the tearing openings extends to 1 / 3-1 / 2 of the thickness of the inner sheath layer.

3. A butterfly optical cable with night vision function according to claim 1, characterized in that, The spacing between adjacent aramid fibers is 0.5-1.2 mm, and the stress-responsive fluorescent fiber is wound in a double helix structure, and the pitch is 3-5 times the diameter of the aramid fiber.

4. The butterfly optical cable with night vision function according to claim 3, characterized in that, The stress-responsive fluorescent fiber is prepared by mixing and extruding polyurethane elastomer, ZnS:Cu particles and SrAl2O4 fluorescent powder in a mass ratio of 11:6:

3.

5. A butterfly optical cable with night vision function according to claim 1, characterized in that, The reflective coating is made by coating glass microbead reflective paint, the particle size of the glass microbead is 20-50 μm, the dry film thickness of the reflective coating is 50%-70% of the diameter of the glass microbead, and the exposed height of the glass microbead accounts for 30%-50% of its diameter.

6. A butterfly optical cable with night vision function according to any one of claims 1 to 5, characterized in that, The reinforcement is any one of aramid fiber bundles, phosphated steel wires or FRP rods, and the diameter of the reinforcement is 0.4-0.6 mm; the optical fiber is a bend-insensitive optical fiber, and the minimum bending radius is 5 mm.

7. A butterfly optical cable with night vision function according to any one of claims 1 to 5, characterized in that, The material of the inner sheath layer is low-smoke halogen-free flame-retardant polyolefin with a surface roughness Ra≤0.8μm. The transparent outer sheath layer is TPU material with a refractive index of 1.50-1.52, to which 0.4-0.6wt% of ultraviolet absorber is added, and the surface roughness Ra≤0.6μm.

8. A butterfly optical cable with night vision function according to any one of claims 1 to 5, characterized in that, The inner surface of the transparent outer sheath layer forms concave patterns corresponding to the pressure of the raised parts of the fluorescent fiber mesh structure.

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