Preparation method of optical fiber sensing skin for ultrasonic monitoring

Abstract

The invention relates to an optical fiber sensing skin preparation method for ultrasonic monitoring. The method comprises the following specific steps: manufacturing a primary filling device and a secondary filling device; a bottom patch with a double-spiral groove is manufactured by using a double-spiral bulge on the surface of a primary filling device and is used for subsequent optical fiber coiling; on the basis of the primary packaging, the secondary filling device is used for coiling sensing optical fibers on the manufactured bottom patch; and finally packaging the bottom patch and the coiled sensing optical fiber by filling a solid acoustic coupling material. The manufacturing process is convenient, the time cost is low, the preparation process is flexible, and multiple sensing modes can be formed according to test requirements.

Description

TECHNICAL FIELD

[0001] The application relates to the monitoring field of distributed optical fiber acoustic sensing, in particular to a preparation method for ultrasonic monitoring optical fiber sensing skin. BACKGROUND

[0002] Optical fiber ultrasonic monitoring technology is a new technology combining optical fiber sensing and ultrasonic detection, which has shown great application potential in many fields.

[0003] Optical fiber ultrasonic sensors perceive relevant information of ultrasonic waves by detecting changes in intensity, wavelength, phase, polarization state and other parameters of light transmitted in the optical fiber. When external ultrasonic waves act on the optical fiber sensor, the parameters of light in the optical fiber will change, and these changes are captured by the sensor and converted into electrical signals, thereby realizing the monitoring of ultrasonic waves.

[0004] Optical fiber ultrasonic monitoring technology has been widely applied in many fields. Underwater national defense security: optical fiber ultrasonic sensors can realize remote monitoring and positioning of underwater targets, providing important support for national defense security;

[0005] Biological imaging: using optical fiber ultrasonic sensors can realize high-resolution imaging of biological tissues, providing a powerful tool for medical research and clinical diagnosis; Power monitoring: optical fiber ultrasonic monitoring technology can realize real-time detection of abnormal discharge of power grids, find potential defects and damage, and has the advantages of long distance and not affecting the power structure.

[0006] As a new non-destructive testing technology, optical fiber ultrasonic monitoring technology has shown great application potential and value in many fields. With the continuous progress and innovation of technology, it is believed that optical fiber ultrasonic monitoring technology will play an even more important role in the future.

[0007] However, the existing ultrasonic monitoring optical fiber sensing skin is mostly designed with small vibration diaphragm, and the layout is discrete, the monitoring range is limited, and a dense array is needed to realize large-scale monitoring, which will significantly increase the complexity and cost. SUMMARY

[0008] The application embodiment provides a preparation method for ultrasonic monitoring optical fiber sensing skin, which is simple and improves the sensitivity of detecting ultrasonic signals.

[0009] To achieve the above purpose, the application provides the following technical scheme:

[0010] The application embodiment provides a preparation method for ultrasonic monitoring optical fiber sensing skin, which comprises the following specific steps:

[0011] Make a filling device and a secondary filling device;

[0012] The double helix protrusions on the surface of the primary filling device are used to make the bottom patch with double helix grooves for subsequent fiber disc arrangement;

[0013] The secondary filling device arranges the sensing optical fiber on the prepared bottom patch on the basis of the primary packaging;

[0014] The bottom patch and the arranged sensing optical fiber are finally packaged by filling the solid acoustic coupling material.

[0015] The primary filling device is composed of a rectangular tray mold and an internal double helix groove, which is used to make a silica gel bottom patch with a double helix groove, specifically,

[0016] The rectangular tray mold has a double helix groove on its inner surface. The groove is uniformly coiled in an s shape. In order to minimize the bending loss of the optical fiber during winding, the curvature radius at the bending point should be as large as possible;

[0017] The groove has a length of one sensing channel, so that there are at least two weak reflection gratings inside the sensing optical fiber;

[0018] The size of the mold is adjusted according to the actual test scene. After filling the filling material and solidifying, a bottom patch with a double helix groove is obtained.

[0019] The secondary filling device is composed of a rectangular tray mold and two micro-holes at both ends, which is used to completely package the sensing optical fiber inside the solid coupling filling material, specifically,

[0020] The size of the rectangular tray mold of the secondary filling device is consistent with that of the primary filling device. The bottom patch obtained by the primary filling device is placed in the secondary filling device. The sensing optical fiber is arranged according to the groove on the patch, while ensuring that at least two sensing points are inside the groove;

[0021] The two ends of the sensing optical fiber are drawn out from the micro-holes of the secondary filling device, and are connected to other required components in the future. Multiple patch optical fiber sensors are connected in series to realize long-distance multi-point monitoring;

[0022] The acoustic coupling material is filled, and after solidification, the packaged optical fiber sensing skin is obtained.

[0023] The solid acoustic coupling material uses polytetrafluoroethylene or polyacid ester.

[0024] The thickness of the optical fiber sensing skin is , and the acoustic wave wavelength is , .

[0025] Compared with the prior art, the application has the advantages that the manufacturing process is convenient, the time cost is low, the preparation process is flexible, various sensing modes can be formed according to test requirements, the optical fiber sensing skin is encapsulated by acoustic coupling material, has good bendability, can wrap the part needing to detect ultrasonic waves, improves the acoustic coupling coefficient, enhances the propagation of acoustic waves, and can be used for long-term measurement while preventing shock, moisture and dust. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 A primary filling device designed for the application;

[0028] Figure 2 A secondary filling device designed for the application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described below in combination with the drawings in the embodiments of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0030] The term "comprising" or "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0031] The terms "first", "second" and the like are only used to distinguish one entity or operation from another entity or operation, and cannot be understood as indicating or implying relative importance, and cannot be understood as requiring or implying any such actual relationship or order between the entities or operations.

[0032] A method for preparing an ultrasonic monitoring optical fiber sensing skin, comprising the following specific steps:

[0033] Making a primary filling device and a secondary filling device;

[0034] The double helix protrusions on the surface of the primary filling device are used to make the bottom patch with double helix grooves for subsequent fiber disc arrangement;

[0035] The secondary filling device arranges the sensing optical fiber on the prepared bottom patch on the basis of the primary packaging;

[0036] The bottom patch and the arranged sensing optical fiber are finally packaged by filling the solid acoustic coupling material.

[0037] The filling material is a solid acoustic coupling material, which can enhance the propagation efficiency of acoustic waves, reduce the influence of air gap on acoustic wave propagation, and improve the sensitivity of monitoring cable joint partial discharge;

[0038] The primary filling device is composed of a rectangular tray mold and an internal double helix groove, which is used to make a silica gel bottom patch with a double helix groove. Specifically:

[0039] The rectangular tray mold has a double helix groove on its inner surface. The groove is uniformly wound in an "s" shape. In order to minimize the bending loss of the optical fiber during winding, the curvature radius at the bending point should be as large as possible;

[0040] In order to allow the sensing optical fiber to detect disturbances, the length of the groove should be long enough. The sensing optical fiber used is a special optical fiber with a weak reflection grating. The groove should have at least the length of one sensing channel, so that there are at least two weak reflection gratings inside the sensing optical fiber;

[0041] The acoustic pressure applied to the grating will cause changes in the effective refractive index and grating period. By using the linear relationship between pressure and Bragg wavelength shift, absolute measurement of acoustic pressure can be achieved;

[0042] The size of the mold is adjusted according to the actual test scene. Since the ultrasonic signal attenuates severely in air, the optical fiber sensing skin should cover the area where ultrasonic signals may be generated as much as possible and be tightly wrapped;

[0043] After filling the filling material and allowing it to solidify, a bottom patch with double helix grooves is obtained;

[0044] The secondary filling device is composed of a rectangular tray mold and two micro-holes at both ends, which is used to completely package the sensing optical fiber inside the solid coupling filling material. Specifically:

[0045] The size of the rectangular tray mold of the secondary filling device is consistent with that of the primary filling device. The bottom patch obtained from the primary filling device is placed in the secondary filling device, and the sensing optical fiber is arranged according to the groove on the bottom patch, while ensuring that at least two sensing points are inside the groove;

[0046] The two ends of the sensing fiber can be led out from the micropores of the secondary filling device and subsequently connected to other required components. Multiple patch fiber optic sensors can be connected in series to achieve long-distance, multi-point monitoring.

[0047] The acoustic coupling material is poured in and solidified to obtain the encapsulated fiber optic sensing skin.

[0048] The filling material is an acoustic coupling material, specifically:

[0049] The filling acoustic coupling material has excellent tear resistance and resilience. It can be wrapped or applied, making it suitable for various monitoring scenarios;

[0050] The acoustic coupling material used for encapsulation should be a material with a large Poisson ratio and a small Young's modulus, which can significantly improve the acoustic pressure sensitivity coefficient of the fiber Bragg grating. Most of them use polymer materials as encapsulation materials, such as polytetrafluoroethylene and polyester.

[0051] Table 1. Pressure Sensitivity of Polymer-Encapsulated Fiber Bragg Gratings with Different Parameters

[0052]

[0053] When using fiber optic sensors on the skin, they should be applied closely to the area where the ultrasound is emitted to reduce the attenuation of the ultrasound signal as it propagates through the air gap.

[0054] For fiber optic sensing of the skin, the thickness should be as thin as possible. According to acoustic propagation theory, sound waves will be reflected and transmitted at multiple interfaces (two or more). The thickness of the dielectric layer is... The wavelength of the sound wave is ,when

[0055] The effect of the dielectric layer on the reflection and refraction of sound waves is negligible. A patch of appropriate thickness is customized based on the monitored ultrasonic wave length.

[0056] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing fiber optic sensing skin for ultrasound monitoring, characterized in that, The specific steps include the following: Fabricate a primary filling device and a secondary filling device; By utilizing the double helix protrusions on the surface of the primary filling device, a bottom patch with double helix grooves is made for subsequent fiber optic coiling. The secondary filling device lays out the sensing optical fiber on the prepared bottom patch based on the primary encapsulation. The bottom patch and the coiled sensing fiber are then encapsulated with a solid acoustic coupling material.

2. The method for preparing fiber optic sensing skin for ultrasound monitoring according to claim 1, characterized in that, The primary filling device consists of a rectangular tray mold and an internal double-helix groove, used to create a silicone substrate with double-helix grooves. Specifically, The inner surface of the rectangular tray mold has double spiral grooves. The grooves are evenly coiled in an S-shape. In order to minimize the bending loss of the optical fiber during coiling, the radius of curvature at the bend should be as large as possible. The groove has a sensing channel length, which means that there are at least two weak reflection gratings inside the sensing fiber. The size of the mold is adjusted according to the actual test scenario. After the filling material is poured in and allowed to solidify, a bottom patch with a double helical groove can be obtained.

3. The method for preparing fiber optic sensing skin for ultrasound monitoring according to claim 1, characterized in that, The secondary filling device consists of a rectangular tray mold and micropores at both ends. Its function is to completely encapsulate the sensing optical fiber inside the solid coupling filling material. Specifically, The rectangular tray mold of the secondary filling device is the same size as that of the primary filling device. The bottom patch obtained from the primary filling device is placed into the secondary filling device, and the sensing fiber is laid out according to the groove on the patch, while ensuring that at least two sensing points are inside the groove. The two ends of the sensing optical fiber are led out from the micropores of the secondary filling device and then connected to other required components to connect multiple patch optical fiber sensors in series, so as to realize long-distance multi-point monitoring. The acoustic coupling material is poured in and, after it solidifies, the encapsulated fiber optic sensing skin is obtained.

4. The method for preparing fiber optic sensing skin for ultrasound monitoring according to claim 1, characterized in that, The solid acoustic coupling material is made of polytetrafluoroethylene or polyester.

5. The method for preparing fiber optic sensing skin for ultrasound monitoring according to claim 1, characterized in that, The thickness of the skin sensed by the optical fiber is The wavelength of the sound wave is , .

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