Sensing optical cable

Abstract

The invention relates to the technical field of cables, and provides a sensing optical cable which comprises a mandrel, a sensing layer and an outer protective layer which are sequentially arranged from inside to outside. The mandrel comprises a tensile element and a transduction layer which are sequentially arranged from inside to outside, the mandrel is divided into a plurality of first mandrels and second mandrels which are alternately connected, a sensitization layer is arranged outside the transduction layer in the first mandrel, the sensing layer comprises a first weaving section and a second weaving section, the first weaving section is arranged on the outer surface of the sensitization layer in the first mandrel, and the second weaving section is arranged on the outer surface of the second weaving section. The second weaving section is arranged on the outer surface of the transduction layer in the second mandrel, and the length of the first weaving section is different from that of the second weaving section. According to the sensing optical cable provided by the invention, by designing a structure in which the first mandrels comprising the sensitization layers and the second mandrels without the sensitization layers are alternately connected and respectively arranging the sensing layers on the outer surfaces of the two mandrels in a weaving form, the optical cable can capture and amplify sound wave vibration signals. The sensibilization layer enhances the response capability of the optical cable to sound wave signals, and improves the overall sensing sensitivity.

Description

Technical Field

[0001] The present invention relates to the field of cable technology, and in particular to a sensor optical cable. Background Art

[0002] Distributed Acoustic Sensing (DAS) technology, as an important branch of Distributed Optical Fiber Sensing System (DOFS), has shown great application potential in many fields in recent years. This technology uses optical fiber as a sensing and transmission medium to achieve comprehensive monitoring of sound and vibration signals, thereby extracting rich feature information of the object to be tested. In particular, in special fields such as oil exploration, seismic wave monitoring, and marine security detection, DAS technology has attracted much attention due to its unique advantages.

[0003] In DAS systems, sensor optical cables play a vital role. They are not only the transmission medium of signals, but also the sensor elements that directly sense the disturbance signals of the external environment. However, the optical cables widely used in the market are mainly traditional commercial communication optical cables. These optical cables are designed mainly for communication performance, without any special optimization for vibration / sound wave sensing functions. Therefore, in practical applications, these optical cables often have problems such as severe signal strength attenuation and weak ability to pick up external sound / vibration signals.

[0004] Specifically, when sound waves or vibration signals are transmitted through optical cables, the signal strength will be greatly attenuated due to the limitations of the optical cable structure and production process. This not only reduces the transmission efficiency of the signal, but also greatly reduces the optical cable's ability to perceive external disturbance signals. Therefore, when traditional communication optical cables are applied to DAS technology, they often cannot meet the high-precision and high-sensitivity detection requirements. Summary of the invention

[0005] The present invention provides a sensing optical cable, which is used to solve the problem that the existing optical cables are difficult to meet the detection requirements of high precision and high sensitivity when applied to DAS technology.

[0006] The present invention provides a sensing optical cable, comprising: a core shaft, a sensing layer and an outer sheath arranged in sequence from the inside to the outside; The core shaft comprises a tensile element and a transducer layer arranged in sequence from the inside to the outside, the core shaft is divided into a plurality of first core shafts and second core shafts connected alternately, and a sensitivity enhancement layer is arranged outside the transducer layer in the first core shaft; The sensing layer includes a first braided segment and a second braided segment. The first braided segment is arranged on the outer surface of the sensitivity enhancement layer in the first core shaft, and the second braided segment is arranged on the outer surface of the transduction layer in the second core shaft. The length of the first braided segment is different from the length of the second braided segment, so that the detection sensitivity of the optical cable changes gradiently.

[0007] The present invention also provides a sensing optical cable, which further comprises: a reinforcement layer arranged between the sensing layer and the outer sheath.

[0008] The present invention also provides a sensing optical cable, wherein the reinforcement layer is provided with a plurality of signal transmission holes which are spaced apart and arranged along the extending direction of the reinforcement layer.

[0009] The present invention also provides a sensing optical cable, wherein the length of the first braided segment is the same as the length of the sensitivity enhancement layer in the first core shaft, and the length of the second braided segment is the same as the length of the energy conversion layer in the second core shaft.

[0010] The present invention also provides a sensing optical cable, wherein the first braided segment and the second braided segment comprise: a plurality of optical units, wherein the plurality of optical units of the first braided segment are woven in a mesh on the outer surface of the sensitivity enhancement layer in the first core shaft, and the plurality of optical units of the second braided segment are woven in a mesh on the outer surface of the energy conversion layer in the second core shaft.

[0011] The present invention also provides a sensing optical cable, wherein the plurality of optical units in the first braided segment and / or the second braided segment are provided with multiple layers, and the optical units in each layer in the first braided segment are sequentially stacked and woven in a mesh shape on the outer surface of the sensitivity enhancement layer in the first core shaft, and the optical units in each layer in the second braided segment are sequentially stacked and woven in a mesh shape on the outer surface of the energy conversion layer in the second core shaft.

[0012] The present invention further provides a sensing optical cable, wherein the weaving density of the plurality of optical units in the first weaving section is greater than the weaving density of the plurality of optical units in the second weaving section.

[0013] The present invention also provides a sensor optical cable, the sensor optical cable further comprising: The covering layer covers the outer surfaces of the plurality of light units of the first braided segment and the second braided segment and is located between the plurality of light units and the outer protective layer.

[0014] The present invention also provides a sensing optical cable, wherein the length of the first braided segment is smaller than the length of the second braided segment.

[0015] The present invention also provides a sensing optical cable, wherein the sound transmission coefficients of the outer sheath, the sensitivity enhancement layer and the transducer layer decrease in sequence, and / or the Young's modulus of the sensitivity enhancement layer, the outer sheath and the transducer layer increase in sequence.

[0016] The sensing optical cable provided by the present invention is designed with a structure in which a first core shaft including a sensitivity enhancement layer and a second core shaft without a sensitivity enhancement layer are alternately connected, and the sensing layer is respectively arranged on the outer surfaces of the two core shafts in a woven form, so that the optical cable can more effectively capture and amplify the acoustic vibration signal. The design of the sensitivity enhancement layer further enhances the responsiveness of the optical cable to the acoustic wave signal, thereby improving the overall perception sensitivity. The tensile element and the transducer layer inside the core shaft work together, not only providing the mechanical strength required for the optical cable, but also ensuring the effective transmission of the acoustic vibration signal inside the optical cable. By arranging the sensing layer on the outer surface of the core shaft in a woven form, the optical cable can better adapt to the surfaces of objects of different shapes and sizes, thereby increasing the applicability and flexibility of the optical cable in complex environments. In addition, the design of the outer sheath not only provides additional protection for the optical cable, but also prevents external environmental factors from damaging the internal structure of the optical cable. This structural design helps to improve the reliability and durability of the optical cable and extend the service life of the optical cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 This is one of the structural schematic diagrams of the sensor optical cable provided by the present invention.

[0019] Figure 2 It is a schematic diagram of the weaving form of the optical unit provided by the present invention.

[0020] Figure 3 Schematic diagram of the mandrel provided by the present invention.

[0021] Figure 4 Schematic diagram of the reinforcement layer provided by the present invention.

[0022] Figure 5 This is the second structural schematic diagram of the sensor optical cable provided by the present invention.

[0023] Reference numerals: 100, core shaft; 1010, tensile element; 1020, transducer layer; 1030, sensitization layer; 200, sensing layer; 2010, first braided segment; 2020, second braided segment; 2030, optical unit; 300, outer protective layer; 400, reinforcement layer; 4010, signal transmission hole; 500, covering layer. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Combine the following Figures 1 to 5 The present invention describes a sensor optical cable, which is applied to DAS technology to meet the detection requirements of high precision and high sensitivity.

[0026] In some embodiments, Figures 1 to 3 As shown, the sensing optical cable includes a core shaft 100, a sensing layer 200 and an outer sheath 300 arranged sequentially from the inside to the outside. The core shaft 100 includes a tensile element 1010 and a transducer layer 1020 arranged sequentially from the inside to the outside. The core shaft 100 is divided into a plurality of first core shafts and second core shafts connected alternately. The transducer layer 1020 in the first core shaft is provided with a sensitivity enhancement layer 1030. The sensing layer 200 includes a first braided segment 2010 and a second braided segment 2020. The first braided segment 2010 is arranged on the outer surface of the sensitivity enhancement layer 1030 in the first core shaft, and the second braided segment 2020 is arranged on the outer surface of the transducer layer 1020 in the second core shaft. The length of the first braided segment 2010 is different from that of the second braided segment 2020, so that the detection sensitivity of the optical cable changes in a gradient, and it is easier to receive the acoustic vibration signals transmitted from different angles.

[0027] In this embodiment, the outer sheath 300 serves as the outermost layer of the optical cable, and the main function of the outer sheath 300 is to protect the optical cable from damage by the external environment, such as wear, corrosion, etc. It is usually made of tough and durable materials to ensure the durability and reliability of the optical cable. The sensing layer 200 is a component in the optical cable responsible for capturing acoustic vibration signals. It consists of a first braided segment 2010 and a second braided segment 2020, which are respectively arranged on the periphery of the first core shaft and the second core shaft. The braided structure not only provides additional strength, but also optimizes the optical cable's ability to receive acoustic signals. The core shaft 100 supports the structure of the entire optical cable and cooperates with the sensing layer 200 to improve the acoustic sensitivity of the optical cable. The core shaft 100 is divided into a plurality of alternately connected first core shafts and second core shafts.

[0028] Specifically, the core shaft 100 is an integrated cylindrical structure with equal diameters, and its function is to support the sensing layer 200 and improve the acoustic sensitivity of the optical cable in cooperation with the sensing layer 200. It has a large cross-sectional area, and the outer diameter of the cross section is not less than 10 mm, in order to increase the sensing area of ​​the optical cable and reduce the optical fiber macrobending loss.

[0029] The tensile element 1010 is made of metal steel wire rope, which is flexible and can ensure that the optical cable has a high tensile strength. For example, the metal steel wire rope structure is "1 7" or "1 19", if 1.0mm steel wire is used, 1 7 structure, metal wire rope outer diameter 3.0mm; using 0.8mm steel wire, 1 19 structure, the outer diameter of the metal steel wire rope is 4.0mm. The energy conversion layer 1020 is continuously coated on the outer periphery of the tensile element 1010 using a polymer material, and extends longitudinally along the tensile element 1010. The sensitization layer 1030 is embedded and coated on the outer periphery of the energy conversion layer 1020 using a polymer material at intervals, and extends longitudinally along the outer periphery of the energy conversion layer 1020.

[0030] When the external sound wave vibration signal is transmitted to the sensing layer 200, part of the signal will be directly captured by the sensing layer 200, and part of the signal will be absorbed by the sensitivity enhancement layer 1030 with a large sound transmission coefficient, which will produce a certain micro deformation, resonate with the sensing layer 200, and amplify the sound wave vibration signal; the remaining part of the signal will be reflected on the surface of the transducer layer 1020 with a small sound transmission coefficient after passing through the sensitivity enhancement layer 1030, and then continue to enter the sensitivity enhancement layer 1030. The three work together to promote as many sound wave vibration signals as possible to be received by the sensing layer 200, thereby improving the sensitivity of optical fiber detection.

[0031] The sensing optical cable provided by the present invention is designed to have a structure in which a first core shaft including a sensitization layer 1030 and a second core shaft without a sensitization layer 1030 are alternately connected, and the sensing layer 200 is respectively arranged on the outer surfaces of the two core shafts 100 in a woven form, so that the optical cable can more effectively capture and amplify the acoustic vibration signal. The design of the sensitization layer 1030 further enhances the responsiveness of the optical cable to the acoustic signal, thereby improving the overall perception sensitivity. The tensile element 1010 and the transducer layer 1020 inside the core shaft 100 work together, not only providing the mechanical strength required for the optical cable, but also ensuring the effective transmission of the acoustic vibration signal inside the optical cable. By arranging the sensing layer 200 on the outer surface of the core shaft 100 in a woven form, the optical cable can better adapt to the surfaces of objects of different shapes and sizes, thereby increasing the applicability and flexibility of the optical cable in complex environments. In addition, the design of the outer sheath 300 not only provides additional protection for the optical cable, but also prevents damage to the internal structure of the optical cable by external environmental factors. This structural design helps to improve the reliability and durability of the optical cable and extend the service life of the optical cable.

[0032] It should be noted that in order to reduce the resistance of the plastic of the outer protective layer 300 to the transmission of external signals and improve the transmission efficiency of signals such as sound waves and vibrations, the outer protective layer 300 also needs to adopt a polymer material with a high sound transmittance coefficient so that the incident sound wave does not reflect a large amount on the surface of the material, thereby reducing the loss of sound wave energy and promoting as much sound wave energy as possible to enter the sensing layer 200.

[0033] In some embodiments, Figures 1 to 4 As shown, the sensing optical cable further includes: a reinforcement layer 400, which is disposed between the sensing layer 200 and the outer sheath 300. The reinforcement layer 400 may be made of a high-strength, high-modulus material, such as aramid fiber, glass fiber or other similar synthetic materials. These materials not only have excellent tensile strength, but also provide the necessary toughness when subjected to external forces, preventing the optical cable from being damaged due to excessive bending or stretching.

[0034] Specifically, when the optical cable laying environment is harsh and the optical cable needs to have a certain compressive strength, a reinforcement layer 400 can be added outside the sensing layer 200, generally using a metal belt / tube coating. Since the acoustic impedance of metal materials is high, that is, the sound transmission coefficient is small, the sound waves and vibration signals transmitted through the outer sheath 300 will be reflected at the metal interface, causing signal attenuation.

[0035] In one example, if Figure 4 As shown, the reinforcement layer 400 is provided with a plurality of signal transmission holes 4010 which are spaced apart and arranged along the extending direction of the reinforcement layer 400 .

[0036] The presence of the signal transmission holes 4010 allows the acoustic vibration signal to be transmitted more smoothly inside the optical cable. These holes can serve as "fast channels" for the acoustic signal, reducing the attenuation and interference of the signal when it propagates inside the optical cable, thereby improving the clarity and accuracy of the signal.

[0037] Furthermore, by providing spaced signal transmission holes 4010 in the reinforcement layer 400, the weight of the optical cable can be effectively reduced without affecting the overall strength of the optical cable. This is particularly important for optical cables that need to be laid over long distances or used in environments such as high altitudes or deep seas, and can reduce the burden of transportation and installation.

[0038] In addition, the signal transmission hole 4010 can also increase the flexibility of the optical cable, making it easier to adapt to various complex environments and terrains. This is particularly useful for installing optical cables on curved or irregular surfaces, ensuring that the optical cable can meet the needs of practical applications while maintaining high performance. The shape of the signal transmission hole 4010 can be circular, elliptical or other shapes suitable for sound wave transmission. The size and spacing of the channel also need to be optimized according to the specific application and needs of the optical cable. The reinforcement layer 400 itself needs to be made of high-strength, high-modulus materials to ensure the mechanical strength of the optical cable. The material around the signal transmission hole 4010 needs to have good sound wave transmission performance to reduce the attenuation of the signal around the channel.

[0039] In some embodiments, Figures 1 to 3 As shown, the length of the first braided segment 2010 is the same as the length of the sensitivity enhancement layer 1030 in the first core shaft, and the length of the second braided segment 2020 is the same as the length of the transducer layer 1020 in the second core shaft.

[0040] In this embodiment, the first braided segment 2010 is tightly wrapped around the outer surface of the sensitizing layer 1030 of the first core shaft, and its length is the same as that of the sensitizing layer 1030. This design ensures that the sensitizing layer 1030 can fully play its role in amplifying the acoustic signal, while the braided segment provides additional mechanical support and protection. Since the braided segment is the same length as the sensitizing layer 1030, the acoustic signal will not be attenuated or interfered during the transmission process due to the gap between the braided segment and the core shaft 100. The second braided segment 2020 is also tightly wrapped around the outer surface of the transducer layer 1020 of the second core shaft, and its length is the same as that of the transducer layer 1020. This design ensures that the transducer layer 1020 can effectively transmit the acoustic vibration signal to the braided segment, and then to other parts of the optical cable. Since the braided segment is the same length as the transducer layer 1020, the acoustic signal can also remain clear and accurate during the transmission process.

[0041] Specifically, the sensitization layer 1030 is in direct contact with the first braided segment 2010 of the optical unit 2030 in the sensing layer 200, and its longitudinal extension length is consistent with the length of the first braided segment 2010; the transducer layer 1020 is in direct contact with the second braided segment 2020 of the optical unit 2030 in the sensing layer 200, and its longitudinal extension length is consistent with the length of the second braided segment 2020, that is, in the first braided segment 2010 of the optical unit 2030, the transverse section of the mandrel 100 includes the tensile element 1010, the transducer layer 1020 and the sensitization layer 1030, and the thickness of the sensitization layer 1030 is 0.5mm to 2mm. In the second braided segment 2020 of the optical unit 2030, the transverse section of the mandrel 100 only includes the tensile element 1010 and the transducer layer 1020, that is, the thickness of the transducer layer 1020 of the second braided segment 2020 is 0.5mm to 2mm greater than that of the transducer layer 1020 of the first braided segment 2010.

[0042] In addition, the sensitivity enhancement layer 1030 can be continuously coated on the periphery of the transducer layer 1020; accordingly, multiple optical units 2030 can be continuously woven with equal pitches. At the same time, the optical unit 2030 can be reinforced with optical fiber, high-performance fiber yarn, and flexible resin. First, the tensile strength of the optical unit 2030 is improved; second, the optical unit 2030 is softer and is conducive to weaving; its size can be controlled at 0.28-0.36 mm, which is more suitable for weaving thin-diameter optical units 2030.

[0043] In some embodiments, Figures 1 to 3 As shown, the first braided segment 2010 and the second braided segment 2020 include: a plurality of light units 2030, the plurality of light units 2030 of the first braided segment 2010 are woven in a mesh on the outer surface of the sensitization layer 1030 in the first core shaft, and the plurality of light units 2030 of the second braided segment 2020 are woven in a mesh on the outer surface of the transduction layer 1020 in the second core shaft.

[0044] Specifically, if Figure 3 As shown, the multiple optical units 2030 of the first braided segment 2010 are tightly woven in a mesh form on the outer surface of the sensitization layer 1030 of the first core shaft. This weaving method ensures close contact between the optical unit 2030 and the sensitization layer 1030, so that the sound wave vibration signal can be effectively captured and transmitted. The mesh weaving also provides additional mechanical support and enhances the tensile and bending resistance of the optical cable. Similar to the first braided segment 2010, the multiple optical units 2030 of the second braided segment 2020 are also tightly woven in a mesh form on the outer surface of the transducer layer 1020 of the second core shaft. This design ensures good contact between the optical unit 2030 and the transducer layer 1020, so that the sound wave vibration signal can be smoothly transmitted to other parts of the optical cable.

[0045] The first braided segment 2010 and the second braided segment 2020 have different lengths (pitch), for example, the length of the first braided segment 2010 is smaller than the length (pitch) of the second braided segment 2020. The braiding pitch L of the light unit 2030 is the distance that the light unit 2030 moves along the axial direction of the sheathing when it circles the mandrel 100. During the braiding process, every two light units 2030 will cross and form overlapping points. The overlapping points of the light units 2030 along the mandrel 1001 inch (25.4mm) are recorded as the braiding mesh number N. The larger N is, the denser the braiding is. The relationship between the braiding pitch L and the braiding mesh number N is: P=25.4 F / 2N=12.7F / N, where F is the number of cores of the optical unit 2030, which is generally an even number, at least 4 cores. Because each optical unit 2030 will be twisted into a mesh structure during the weaving process, its twisting direction will change with the core shaft 100, so that the sensing layer 200 can sense external signals in all directions. Compared with the optical unit 2030 that is wound on the surface of the core shaft 100, the woven optical unit 2030 is more likely to receive sound wave vibration signals transmitted from different angles, making the detection more sensitive.

[0046] In this embodiment, the optical unit 2030 has a size of 0.25 to 0.9 mm, and its structure is that a plastic layer with a high sound transmission coefficient is tightly coated on the outer side of the optical fiber, such as a thermoplastic elastomer similar to the core shaft 100 sensitivity enhancement layer 1030; the optical fiber in the optical unit 2030 adopts a grating optical fiber, that is, each optical fiber is provided with a plurality of continuous grating arrays, and the grating length, spacing and wavelength can be controlled by the writing technology of the optical fiber grating; compared with ordinary optical fiber, grating optical fiber can more easily realize vibration, stress and strain monitoring at the micro-strain level.

[0047] Furthermore, by controlling the weaving pitch and weaving length of the optical unit 2030, it is ensured that two adjacent grating points are exactly located at the starting point and the end point of each first pitch / second weaving section 2020. In this way, by demodulating the changes in the grating points, the specific position of the external sound wave vibration signal can be tracked, which is more conducive to the precise positioning of the optical cable to perceive the external signal.

[0048] In one example, the sensing layer 200 formed by weaving the optical units 2030, the sensing optical cable further includes: a coating layer 500. The coating layer 500 covers the outer surfaces of the plurality of optical units 2030 of the first braided segment 2010 and the second braided segment 2020, and is located between the plurality of optical units 2030 and the outer sheath 300.

[0049] The coating layer 500 can be coated with a composite tape of a foamed plastic layer and a polyester film. This method can firstly play a role of fixing and protecting; secondly, the softness of the foamed composite tape can be used to fill the gaps formed by weaving adjacent light units 2030 during the coating process, thereby reducing the air's obstruction to the sound wave vibration signal transmitted from the outside world; thirdly, the porous characteristics of the foamed composite tape can be used to form a sound-containing cavity in the sensing layer 200, which can easily absorb the sound wave vibration signal.

[0050] In some embodiments, Figures 1 to 5 As shown, the multiple light units 2030 in the first braided segment 2010 and / or the second braided segment 2020 are provided in multiple layers, and the layers of light units 2030 in the first braided segment 2010 are sequentially stacked and mesh-woven on the outer surface of the sensitization layer 1030 in the first core shaft, and the layers of light units 2030 in the second braided segment 2020 are sequentially stacked and mesh-woven on the outer surface of the transduction layer 1020 in the second core shaft.

[0051] Among them, in the first braided section 2010, each layer of optical unit 2030 is stacked in sequence and woven in a mesh shape on the outer surface of the sensitivity layer 1030 of the first core shaft. This design ensures close contact between the optical unit 2030 and the sensitivity layer 1030, and due to the existence of the multi-layer structure, the acoustic vibration signal can be effectively transmitted and amplified between the optical units 2030 of different layers. In addition, the multi-layer braiding also provides additional mechanical support, enhancing the tensile and bending resistance of the optical cable. Similar to the first braided section 2010, each layer of optical unit 2030 in the second braided section 2020 is also stacked in sequence and woven in a mesh shape on the outer surface of the transducer layer 1020 of the second core shaft. This design enables the acoustic vibration signal to be smoothly transmitted to other parts of the optical cable, and after being amplified and processed by the multi-layer optical unit 2030, the detection accuracy and sensitivity of the acoustic signal are improved.

[0052] The number of layers can be further adjusted as needed. As the number of layers increases, the woven mesh will become denser and the range of its woven angle coverage will be wider, which is more conducive to sensing the sound wave vibration signals transmitted from different external angles.

[0053] Generally, the weaving density of the plurality of light units 2030 in the first weaving segment 2010 is greater than the weaving density of the plurality of light units 2030 in the second weaving segment 2020 .

[0054] Since the first braided segment 2010L1 is smaller than the second braided segment 2020L2, and L1<(0.2~0.5) L2; makes the light units 2030 denser in the first weaving segment 2010 and more sparse in the second weaving segment 2020, thereby forming obvious sparse and dense weaving segments.

[0055] By setting the sparse and dense braided segments, the limited length of the optical cable resources can be maximized according to the needs of the detection scene on the one-dimensional continuous detection path of the optical cable, thereby reducing the manufacturing cost of the optical cable. At the same time, the sparse and dense braided segments correspond exactly to the core shaft 100, the transducer layer 1020, and the sensitivity enhancement layer 1030, so that the detection sensitivity of the optical cable changes in a gradient, which is more suitable for the application scenario of the optical cable.

[0056] For example, due to the high density in the first woven segment 2010, the signal collection density of the sensing light unit 2030 in the first woven segment 2010 is improved, and in synergy with the sensitivity enhancement layer 1030, the detection sensitivity of the optical cable will be significantly improved.

[0057] In some embodiments, Figure 1As shown, a plurality of tensile elements 1010 are provided, and a transducer layer 1020 is wrapped outside the plurality of tensile elements 1010. The parallel use of the plurality of tensile elements 1010 significantly enhances the tensile strength of the optical cable, enabling it to withstand greater external forces and more complex environmental conditions. The transducer layer 1020 is tightly wrapped around the outer side of the tensile element 1010, ensuring that the acoustic vibration signal can be effectively transmitted from the outside to the inside of the optical cable. This structural design not only enhances the mechanical properties of the optical cable, but also improves the reliability and stability of the optical cable in acoustic monitoring applications by optimizing the transmission path and efficiency of the acoustic signal.

[0058] In some embodiments, Figures 1 to 4 As shown, the transducer layer 1020 and the sensitivity enhancement layer 1030 are made of polymer materials with different sound transmission coefficients, and the sound transmission coefficient of the sensitivity enhancement layer 1030 is significantly higher than that of the transducer layer 1020. (The sound transmission coefficient is the ratio of the internal sound field intensity to the external sound field intensity under the sound pressure of a specific external frequency. The larger the sound transmission coefficient, the less the sound wave is reflected on the surface of the material, which reduces the sound wave energy loss. The smaller the sound transmission coefficient, the easier it is for the sound wave to be reflected on the surface of the material).

[0059] The test surface shows that at a sound pressure frequency of 20Hz to 2000Hz, the smaller the Young's modulus of the plastic layer, the greater its sound transmission coefficient. Therefore, the Young's modulus of the transducer layer 1020 of the sensing optical cable provided in this embodiment is greater than that of the sensitizing layer 1030, generally at least 5 times higher. Generally, the transducer layer 1020 uses a polymer plastic with a Young's modulus of 2000 to 4000 MPa, a typical material such as polyvinyl chloride. The sensitizing layer 1030 uses a polymer plastic with a Young's modulus of 400 to 600 MPa, a typical material such as a thermoplastic elastomer.

[0060] In addition, the plastic layer with a small Young's modulus can produce higher micro-deformation under the excitation of external sound wave vibration, and the sensing layer 200 can resonate together and amplify the sound wave vibration signal, thereby improving the acoustic sensitivity performance of the optical cable.

[0061] Generally, the outer sheath 300 is the outermost layer of the optical cable, and its main function is to provide mechanical protection and durability. The same thermoplastic elastomer material as the core shaft 100 sensitization layer 1030 is used, but the Young's modulus is higher, in order to ensure that the optical cable can withstand external pressure and wear in complex environments (such as underwater, underground, etc.). Materials with high Young's modulus can provide better structural support and prevent the optical cable from being damaged by external forces. The outer sheath 300 can be made of hollow glass microspheres, vermiculite powder, montmorillonite, etc. These fillers can form a porous structure inside the material, which helps to improve the sound transmission coefficient while maintaining a certain mechanical strength.

[0062] In this embodiment, the relationship between the acoustic transmission coefficient and Young's modulus of the outer protective layer 300, the sensitivity enhancement layer 1030 and the transducer layer 1020 is: Sound transmission coefficient: outer protective layer 300>sensitization layer 1030>transducer layer 1020. The obstacles encountered by the sound wave when propagating in the outer protective layer 300 are minimal, which is conducive to the capture and transmission of the sound wave signal.

[0063] Young's modulus: sensitization layer 1030<outer sheath 300<transducer layer 1020. The optical cable can provide necessary structural support and stability while maintaining sufficient flexibility.

[0064] Furthermore, when the sensor optical cable is used for underwater monitoring, the influence of water flow noise needs to be reduced. The surface of the outer sheath 300 may have a hydrophobic, low-friction coating. Common coating materials include silane-modified polymers, polymer surface co-constructed polymers, nanoparticles, etc.

[0065] In a specific embodiment, the sensing layer 200 can be coated and fixed with a composite tape of a resin instead of a foamed plastic layer and a polyester film; that is, a layer of resin with a thickness of 0.15 to 0.35 mm is coated on the surface of the woven sensing layer 200. The typical characteristics of the resin are: viscosity (25°C), 3000 to 4000 mPa.s, and after curing: tensile strength (25°C) is 8 MPa to 15 MPa, elongation (25°C) is 5% to 12%, elastic modulus (25°C) is 150 MPa to 250 MPa, and hardness (HD) is 30 to 50. The resin has low tensile strength and elongation at break, low elastic modulus, is softer, and can be deformed, which is more conducive to the light unit 2030 being attached to the surface of the mandrel 100, and can also undergo micro-deformation with the mandrel 100.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sensor optical cable, characterized in that: include: A core shaft (100), a sensing layer (200) and an outer protective layer (300) are sequentially arranged from the inside to the outside; The core shaft (100) comprises a tensile element (1010) and an energy conversion layer (1020) arranged in sequence from the inside to the outside, the core shaft (100) is divided into a plurality of first core shafts and second core shafts connected alternately, and a sensitivity enhancement layer (1030) is arranged outside the energy conversion layer (1020) in the first core shaft; The sensing layer (200) comprises a first braided segment (2010) and a second braided segment (2020); the first braided segment (2010) is arranged on the outer surface of the sensitivity enhancement layer (1030) in the first core shaft, and the second braided segment (2020) is arranged on the outer surface of the transducer layer (1020) in the second core shaft; the length of the first braided segment (2010) is different from the length of the second braided segment (2020), so that the detection sensitivity of the optical cable changes in a gradient.

2. The sensing optical cable according to claim 1, characterized in that: The sensing optical cable further comprises: a reinforcement layer (400) arranged between the sensing layer (200) and the outer sheath (300).

3. The sensing optical cable according to claim 2, characterized in that: The reinforcement layer (400) is provided with a plurality of signal transmission holes (4010) which are spaced apart and arranged along the extension direction of the reinforcement layer (400).

4. The sensing optical cable according to claim 1, characterized in that: The length of the first braided segment (2010) is the same as the length of the sensitivity enhancement layer (1030) in the first core shaft, and the length of the second braided segment (2020) is the same as the length of the energy conversion layer (1020) in the second core shaft.

5. The sensing optical cable according to claim 1, characterized in that: The first braided segment (2010) and the second braided segment (2020) comprise: a plurality of light units (2030); the plurality of light units (2030) of the first braided segment (2010) are woven in a mesh shape on the outer surface of the sensitivity enhancement layer (1030) in the first core shaft; and the plurality of light units (2030) of the second braided segment (2020) are woven in a mesh shape on the outer surface of the transducer layer (1020) in the second core shaft.

6. The sensing optical cable according to claim 5, characterized in that: The plurality of light units (2030) in the first braided segment (2010) and / or the second braided segment (2020) are provided with multiple layers, and the layers of light units (2030) in the first braided segment (2010) are sequentially stacked and woven in a mesh shape on the outer surface of the sensitivity enhancement layer (1030) in the first core shaft, and the layers of light units (2030) in the second braided segment (2020) are sequentially stacked and woven in a mesh shape on the outer surface of the transducer layer (1020) in the second core shaft.

7. The sensing optical cable according to claim 5, characterized in that: The weaving density of the plurality of light units (2030) in the first weaving segment (2010) is greater than the weaving density of the plurality of light units (2030) in the second weaving segment (2020).

8. The sensing optical cable according to claim 5, characterized in that: The sensor optical cable also includes: The coating layer (500) is coated on the outer surfaces of the plurality of light units (2030) of the first braided segment (2010) and the second braided segment (2020), and is located between the plurality of light units (2030) and the outer protective layer (300).

9. The sensing optical cable according to claim 1, characterized in that: The length of the first braided segment (2010) is smaller than the length of the second braided segment (2020).

10. The optical sensing cable according to any one of claims 1 to 9, characterized in that: The sound transmission coefficients of the outer protective layer (300), the sensitivity enhancement layer (1030), and the transducer layer (1020) decrease in sequence, and / or the Young's modulus of the sensitivity enhancement layer (1030), the outer protective layer (300), and the transducer layer (1020) increase in sequence.

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