Fabry-Perot ultrasonic sensor with SMS structure
The SMS structure Fabry-Perot ultrasonic sensor solves the problems of easy damage and insufficient sensitivity of traditional fiber optic Fabry-Perot sensors in transformer windings by constructing a Fabry-Perot interference cavity that does not require additional lenses or gratings, thus achieving stable detection and efficient sensing of weak partial discharge ultrasonic signals.
Patent Information
- Application Number
- CN202511028978.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-11-04
AI Technical Summary
Traditional fiber optic Fabry-Perot ultrasonic sensors are easily damaged in transformer windings, have insufficient sensitivity, and are costly. Existing technologies are complex and cannot effectively detect weak partial discharge ultrasonic signals.
An SMS-structured Fabry-Perot ultrasonic sensor is used. A Fabry-Perot interferometric cavity is constructed by sequentially arranging and fusion splicing a first single-mode fiber, a multimode fiber, and a second single-mode fiber. The cavity length is constructed by utilizing the refractive index difference at the fusion interface. The multimode fiber and the fusion area are encapsulated with a protective shell to enhance anti-interference capability and mechanical strength, ensuring that ultrasonic waves are transmitted into the interferometric cavity.
It enables stable detection of weak partial discharge ultrasonic signals inside transformers, reducing manufacturing costs, improving structural stability and sensing sensitivity, and adapting to the confined space of transformers.
Smart Images
Figure CN120890537A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of sensor technology, and in particular to an SMS structure Fabry-Perot ultrasonic sensor. Background Technology
[0002] Ultrasonic waves generated by partial discharges within the windings of a power transformer are absorbed or reflected by the transformer's complex internal mechanical structure. Traditional piezoelectric ultrasonic sensors cannot measure the weak partial discharge ultrasonic signals generated within the transformer windings.
[0003] Therefore, fiber optic Fabry-Perot ultrasonic sensors, characterized by strong insulation, small size, and ease of integration, have been widely researched and applied in the ultrasonic detection of partial discharge in power equipment. Fiber optic Fabry-Perot ultrasonic sensing technology is divided into intrinsic Fabry-Perot sensing technology and extrinsic sensing technology. Extrinsic Fabry-Perot sensing technology refers to achieving interference by forming a Fabry-Perot interference cavity with a high-reflectivity diaphragm and the fiber end face. Intrinsic Fabry-Perot sensing technology refers to using femtosecond lasers to write dual fiber gratings in a single-mode fiber to form a reflector.
[0004] However, the diaphragm of the non-intrinsic Fabry-Perot sensor is easily damaged in the strong electromagnetic environment of the transformer due to its weak encapsulation protection (thickness is usually ≤5 mm and radius is ≤15 mm), and the diaphragm size limitation leads to insufficient sensitivity and reliability. The intrinsic Fabry-Perot sensor relies on high-precision femtosecond laser writing grating, which is complicated and costly, and the consistency of grating wavelength is difficult to guarantee, resulting in a low yield. Summary of the Invention
[0005] Therefore, it is necessary to provide an SMS structure Fabry-Perot ultrasonic sensor to address the problems of weak insulation performance, complex manufacturing process, high cost, and limited structural size of existing fiber optic Fabry-Perot sensors in transformer winding installation scenarios.
[0006] This application provides an SMS structure Fabry-Perot ultrasonic sensor, the SMS structure Fabry-Perot ultrasonic sensor comprising:
[0007] A first single-mode fiber, a multimode fiber, and a second single-mode fiber are sequentially arranged and fused together. The fusion areas of the first single-mode fiber and the multimode fiber, as well as the second single-mode fiber and the multimode fiber, respectively form reflective end faces to construct a Fabry-Perot interferometer cavity. The cavity length of the Fabry-Perot interferometer cavity is the length of the multimode fiber.
[0008] A protective enclosure is provided to cover the multimode optical fiber and the two fusion splice areas, and to connect the first single-mode optical fiber and the second single-mode optical fiber; the protective enclosure is provided with a sound transmission hole.
[0009] In one of the embodiments, the packaging protective shell comprises a shell and an end plate arranged at one end of the shell, the shell covers the multi-mode optical fiber and the two fusion regions, and the end plate abuts against the second single-mode optical fiber, and the sound hole is arranged on the end plate.
[0010] In one of the embodiments, a plurality of sound holes are arranged, and the plurality of sound holes are arranged at intervals around the arrangement direction of the first single-mode optical fiber, the multi-mode optical fiber and the second single-mode optical fiber.
[0011] In one of the embodiments, the packaging protective shell is connected with the first single-mode optical fiber and the second single-mode optical fiber respectively by chemical bonding.
[0012] In one of the embodiments, the length of the multi-mode optical fiber is 50 μm-1000 μm.
[0013] In one of the embodiments, the first single-mode optical fiber comprises a first single-mode core and a first single-mode cladding, and the first single-mode cladding wraps the first single-mode core.
[0014] In one of the embodiments, the second single-mode optical fiber comprises a second single-mode core and a second single-mode cladding, and the second single-mode cladding wraps the second single-mode core.
[0015] In one of the embodiments, the diameter of the first single-mode core and / or the second single-mode core is 9 μm, and the diameter of the first single-mode cladding and / or the second single-mode cladding is 125 μm.
[0016] In one of the embodiments, the multi-mode optical fiber comprises a multi-mode core and a multi-mode cladding, the multi-mode cladding wraps the multi-mode core, the diameter of the multi-mode core is 50 μm, and the diameter of the multi-mode cladding is 125 μm.
[0017] In one of the embodiments, the packaging protective shell is made of epoxy resin material.
[0018] The above SMS structure Fabry-Perot ultrasonic sensor arranges and fuses the first single-mode optical fiber, the multi-mode optical fiber and the second single-mode optical fiber in sequence to form a single-mode-multi-mode-single-mode (SMS) fusion structure, uses the refractive index difference of the fusion interface to construct a Fabry-Perot interference cavity, and directly uses the length of the multi-mode optical fiber as the cavity length. This structure does not need to additionally set a diaphragm or engrave a grating by femtosecond laser, saves the complex process of external mirrors or engraved gratings, avoids the problem that the diaphragm in the extrinsic Fabry-Perot sensor is easily damaged due to weak packaging, reduces the manufacturing cost and improves the structural stability.
[0019] And the encapsulation protection shell covers the multi-mode optical fiber and the fusion area and is connected with the first single-mode optical fiber and the second single-mode optical fiber, which can provide effective protection for the core interference structure, enhance the anti-interference ability and mechanical strength of the sensor in the strong electromagnetic and high-temperature environment inside the transformer. The sound hole on the encapsulation protection shell ensures that the ultrasonic waves generated by the partial discharge can smoothly enter the interference cavity, ensuring the sensing sensitivity. The overall structure is compact, suitable for the narrow space inside the transformer winding, and realizes stable detection of weak partial discharge ultrasonic signals. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 The structure diagram of the SMS structure Fabry-Perot ultrasonic sensor provided by the embodiment of the application is shown.
[0021] Reference signs:
[0022] 100, first single-mode optical fiber; 110, first single-mode core; 120, first single-mode cladding;
[0023] 200, multi-mode optical fiber; 210, multi-mode core; 220, multi-mode cladding;
[0024] 300, second single-mode optical fiber; 310, second single-mode core; 320, second single-mode cladding;
[0025] 400, encapsulation protection shell; 410, shell body; 420, end plate;
[0026] 500, sound hole. DETAILED DESCRIPTION
[0027] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the application. However, the application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the application, therefore the application is not limited by the specific embodiments disclosed below.
[0028] In the description of the application, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.
[0029] In addition, the terms "first", "second", and the like, if any, are used herein for descriptive purposes only and should not be construed as indicating or implying relative importance or identifying the number of the indicated technical characteristics. Thus, a feature defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "a plurality of" appears, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.
[0030] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be interpreted broadly. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0031] In the present application, unless otherwise explicitly specified and limited, if the first feature is described as "on" or "under" the second feature, etc., it can mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be the first feature directly above or obliquely above the second feature, or it can only mean that the first feature is higher than the second feature in horizontal height. The first feature "below", "below" and "below" the second feature can be the first feature directly below or obliquely below the second feature, or it can only mean that the first feature is lower than the second feature in horizontal height.
[0032] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are only for illustrative purposes and do not represent the only implementation.
[0033] The present application provides an SMS structure fiber-optic ultrasonic sensor, such as Figure 1 As shown, the SMS structure fiber-optic ultrasonic sensor comprises:
[0034] The first single-mode optical fiber 100, the multi-mode optical fiber 200 and the second single-mode optical fiber 300 are arranged and fused in sequence, and the fusion regions of the first single-mode optical fiber 100 and the multi-mode optical fiber 200 and the second single-mode optical fiber 300 and the multi-mode optical fiber 200 form reflection end faces respectively to construct a Fabry-Perot interference cavity, and the cavity length of the Fabry-Perot interference cavity is the length of the multi-mode optical fiber 200.
[0035] The packaging protective shell 400 covers the multi-mode optical fiber 200 and the two fusion regions and is connected to the first single-mode optical fiber 100 and the second single-mode optical fiber 300, and the packaging protective shell 400 is provided with a sound hole 500.
[0036] The first single-mode optical fiber 100, the multi-mode optical fiber 200 and the second single-mode optical fiber 300 are arranged and fused in sequence to form a single-mode-multi-mode-single (SMS) fusion structure, a Fabry-Perot interference cavity is constructed by using the refractive index difference of the fusion interface, and the length of the multi-mode optical fiber 200 is directly used as the cavity length. This structure does not need to additionally set a diaphragm or engrave a grating by using a femtosecond laser, and the complex process of an external mirror or engraved grating is omitted, the problem that the diaphragm is easily damaged due to weak packaging in an extrinsic Fabry-Perot sensor is avoided, the manufacturing cost is reduced, and the structural stability is improved.
[0037] The packaging protective shell 400 covers the multi-mode optical fiber 200 and the fusion regions and is connected to the first single-mode optical fiber 100 and the second single-mode optical fiber 300, and the packaging protective shell 400 is provided with a sound hole 500.
[0038] It should be noted that fusion refers to the butt joint solidification of the end faces of two optical fibers after high-temperature fusion by using an electric arc fusion technology, and a permanent optical connection is formed. The fusion region refers to the butt joint fusion interface of the first single-mode optical fiber 100 and the multi-mode optical fiber 200 and the butt joint fusion interface of the second single-mode optical fiber 300 and the multi-mode optical fiber 200.
[0039] It should be noted that the definition of the traditional Fabry-Perot cavity can be summarized as follows: an optical resonant structure composed of two parallel or approximately parallel high-reflectivity mirrors, in which multiple reflections of light waves between the mirrors form a multi-beam interference, and the transmission / reflection spectrum has wavelength selectivity and is highly sensitive to changes in cavity length or refractive index in the cavity. In this application, the Fabry-Perot cavity does not require traditional mirrors, but uses the refractive index jump of the fiber fusion interface to construct the reflecting surface: two fusion regions form double reflecting surfaces, and the middle multimode fiber acts as a solid-state medium cavity. The SMS fiber structure of the present application realizes a mirror-free, all-fiber, and highly robust Fabry-Perot cavity through the fusion region, which meets the stringent requirements of the built-in ultrasonic sensor of the transformer. In one embodiment, as shown in Figure 1 The packaging protective shell 400 includes a shell 410 and an end plate 420 arranged at one end of the shell 410, the shell 410 covers the multimode fiber 200 and the two fusion regions, and the end plate 420 abuts the second single-mode fiber 300, and the end plate 420 is provided with a sound hole 500. The shell 410 and the end plate 420 cooperate to form an open packaging space, the shell 410 forms circumferential protection for the multimode fiber 200 and the fusion region, and the end plate 420 abuts the second single-mode fiber 300 from the axial direction (the arrangement direction of the first single-mode fiber 100, the multimode fiber 200, and the second single-mode fiber 300), further limiting the displacement of the core optical structure, enhancing the stability of the overall structure, and avoiding the loosening of the fiber connection caused by the vibration inside the transformer.
[0040] At the same time, the sound hole 500 is arranged on the end plate 420, so that the ultrasonic wave can be accurately transmitted into the Fabry-Perot interference cavity inside the packaging shell along the axial direction, reducing the energy loss of the sound wave in the propagation path, ensuring the effective sensing of the interference cavity to the ultrasonic signal, and the split packaging design provides comprehensive protection while not affecting the sequential fusion relationship of the first single-mode fiber 100, the multimode fiber 200, and the second single-mode fiber 300, further improving the structural reliability and sensing accuracy of the sensor.
[0041] In one embodiment, as shown in Figure 1 The sound hole 500 is provided with a plurality of sound holes 500, and the plurality of sound holes 500 are arranged in a circumferentially spaced manner around the arrangement direction of the first single-mode fiber 100, the multimode fiber 200, and the second single-mode fiber 300. Through the circumferentially spaced multiple sound holes 500, the ultrasonic wave generated by the partial discharge of the transformer winding can be transmitted into the Fabry-Perot interference cavity inside the packaging protective shell 400 from multiple directions, avoiding the directional limitation of the sound wave that may exist in a single sound hole 500, increasing the action opportunity of the sound wave and the interference cavity, and reducing the signal loss caused by the deviation of the sound wave propagation angle.
[0042] Meanwhile, the arrangement mode of the plurality of sound holes 500 does not affect the covering protection function of the shell 410 on the multimode optical fiber 200 and the fusion area, nor change the abutting relationship between the end plate 420 and the second single-mode optical fiber 300, further improving the sensing sensitivity and detection range of the sensor to ultrasonic signals in different directions, and ensuring effective capture of weak partial discharge signals.
[0043] In one of the embodiments, the packaging protective shell 400 is connected with the first single-mode optical fiber 100 and the second single-mode optical fiber 300 respectively by chemical bonding. By using the high-strength connection characteristics of chemical bonding, a stable combination is formed between the packaging protective shell 400 and the optical fibers, avoiding the looseness or gap that may occur in traditional mechanical connection, ensuring that the packaging protective shell 400 can always tightly cover the multimode optical fiber 200 and the two fusion areas, effectively blocking the intrusion of impurities such as oil stains and dust inside the transformer into the core interference structure, and improving the sealing performance of the sensor.
[0044] Meanwhile, this connection mode does not affect the fusion relationship between the first single-mode optical fiber 100, the multimode optical fiber 200 and the second single-mode optical fiber 300 and the formation of the reflection end face, nor interfere with the transmission of ultrasonic waves by the sound hole 500, further enhancing the mechanical strength and environmental adaptability of the overall structure of the sensor, so that it can maintain reliable performance under the complex working conditions of long-term operation of the transformer.
[0045] In one of the embodiments, the length of the multimode optical fiber 200 is 50-1000 μm. By limiting the length of the multimode optical fiber 200 to a specific range, the F-P interference cavity with this cavity length can adapt to the frequency characteristics of the transformer partial discharge ultrasonic signal. When the length of the multimode optical fiber 200 is in this interval, the optical path difference between the reflection end faces can form effective interference with the optical path change caused by the ultrasonic wave, ensuring that the interference signal has sufficient contrast and sensitivity, and avoiding weak interference signal due to too short cavity length or signal attenuation caused by too long length.
[0046] Meanwhile, the multimode optical fiber 200 with this length range, after being fused with the first single-mode optical fiber 100 and the second single-mode optical fiber 300, has a compact overall structure, which does not increase the size of the packaging protective shell 400 due to the excessive length of the multimode optical fiber 200, adapts to the narrow space inside the transformer winding, and does not affect the covering protection function of the packaging protective shell 400 and the sound wave transmission function of the sound hole 500, further improving the detection adaptability and precision of the sensor to the partial discharge ultrasonic signal.
[0047] In one of the embodiments, as shown in FIG. 1, the packaging protective shell 400 is connected with the first single-mode optical fiber 100 and the second single-mode optical fiber 300 respectively by chemical bonding. Figure 1As shown, the first single-mode optical fiber 100 comprises a first single-mode core 110 and a first single-mode cladding 120, and the first single-mode cladding 120 wraps the first single-mode core 110. By cladding the first single-mode core 110 with the first single-mode cladding 120, the stable transmission of the optical signal in the core is achieved by the difference in refractive index between the two, avoiding the leakage of light when propagating in the first single-mode optical fiber 100, ensuring that the incident light can efficiently reach the fusion area with the multimode optical fiber 200; at the same time, such a double-layer structure of core-cladding provides a certain mechanical strength for the first single-mode optical fiber 100, facilitating accurate fusion with the multimode optical fiber 200 to form a stable reflection end face, without affecting the connection relationship between the first single-mode optical fiber 100 and the packaging protective shell 400, nor interfering with the normal operation of the Fabry-Perot interference cavity, further improving the stability of optical signal transmission and the structural reliability of the optical fiber itself, providing a basic guarantee for efficient sensing of the sensor.
[0048] In one of the embodiments, as shown in Figure 1 The second single-mode optical fiber 300 comprises a second single-mode core 310 and a second single-mode cladding 320, and the second single-mode cladding 320 wraps the second single-mode core 310. By cladding the second single-mode core 310 with the second single-mode cladding 320, the stable transmission of the optical signal reflected by the Fabry-Perot interference cavity in the second single-mode core 310 is ensured by the difference in refractive index between the two, reducing the loss of the optical signal in the output path and improving the transmission efficiency of the interference signal; at the same time, such a double-layer structure enhances the mechanical strength of the second single-mode optical fiber 300, making the fusion with the multimode optical fiber 200 more stable, ensuring the stability of the reflection end face formed by the fusion area, without affecting the abutting relationship between the second single-mode optical fiber 300 and the packaging protective shell 400, nor interfering with the reception of ultrasonic waves by the sound hole 500, further optimizing the output transmission performance of the optical signal, ensuring that the sensor can efficiently output the interference signal reflecting the partial discharge.
[0049] In one of the embodiments, the diameter of the first single-mode core 110 and / or the second single-mode core 310 is 9 μm, and the diameter of the first single-mode cladding 120 and / or the second single-mode cladding 320 is 125 μm. By specifying the size parameters of the single-mode fiber core and cladding, the fusion of the first single-mode optical fiber 100, the second single-mode optical fiber 300 and the multimode optical fiber 200 is more likely to form a stable refractive index difference interface, ensuring the consistency of the reflectivity of the reflection end face and reducing the fluctuation of the light reflection efficiency caused by size mismatch; at the same time, the cladding diameter of 125 μm provides sufficient structural strength for the optical fiber, facilitating the formation of a stable connection with the packaging protective shell 400, and the core diameter of 9 μm is suitable for single-mode optical transmission characteristics, ensuring low-loss transmission of the optical signal in the core, and this size design makes the overall structure of the single-mode optical fiber compact, without affecting the miniaturization feature of the SMS structure composed of the multimode optical fiber 200, further improving the stability of optical signal reflection and transmission, and enhancing the batch production consistency of the sensor.
[0050] In the embodiment, the length of the first single-mode optical fiber 100 is greater than the length of the second single-mode optical fiber 300. By differentiating the lengths of the two single-mode optical fibers, the first single-mode optical fiber 100 can provide a longer stable transmission path for the incident light signal, ensure that the incident light maintains good mode characteristics before reaching the fusion area with the multimode optical fiber 200, and reduce mode distortion during transmission. At the same time, the shorter second single-mode optical fiber 300 can ensure effective output of the reflected light signal while avoiding signal attenuation caused by excessive length, and does not affect the fusion of the two single-mode optical fibers with the multimode optical fiber 200 to form a reflection end face, nor does it interfere with the encapsulation and protection shell 400 covering the core structure and the sound transmission hole 500. The function further optimizes the stability of the incident light signal and the output efficiency of the reflected signal, and improves the response accuracy of the sensor to the partial discharge ultrasonic signal.
[0051] In one of the embodiments, as shown in Figure 1 The multimode optical fiber 200 includes a multimode core 210 and a multimode cladding 220, and the multimode cladding 220 wraps the multimode core 210. The diameter of the multimode core 210 is 50 μm, and the diameter of the multimode cladding 220 is 125 μm. By specifying the size of the multimode core 210 and the multimode cladding 220 of the multimode optical fiber 200, the multimode optical fiber 200 can stably form a reflection end face when fused with the first single-mode optical fiber 100 and the second single-mode optical fiber 300. The 50 μm diameter of the multimode core 210 provides sufficient space for multimode transmission of light in the Fabry-Perot interference cavity, ensuring effective interference of light between the reflection end faces and improving the intensity of the interference signal. At the same time, the 125 μm diameter of the multimode cladding 220 matches the size of the first single-mode cladding 120 and the second single-mode cladding 320, facilitating precise fusion and ensuring the structural stability of the fusion area.
[0052] Moreover, the size design makes the SMS structure composed of the multimode optical fiber 200 and the single-mode optical fiber compact as a whole, without affecting the encapsulation effect of the encapsulation and protection shell 400 and the sound wave transmission of the sound transmission hole 500, further optimizing the interference effect of light and the reliability of fiber connection, and enhancing the sensing sensitivity of the sensor to the partial discharge ultrasonic signal.
[0053] In one of the embodiments, the encapsulation and protection shell 400 is made of epoxy resin material. Epoxy resin material has excellent insulation performance, can effectively resist the strong electromagnetic environment inside the transformer, avoid the sensor itself becoming a weak insulation point, and ensure the safe operation of the transformer. At the same time, the epoxy resin has high hardness and good mechanical strength, can form a firm encapsulation of the multimode optical fiber 200 and the two fusion areas, resist the influence of internal vibration or impact of the transformer on the core optical structure, and has strong chemical stability and is not easily eroded by environmental factors such as oil pollution and high temperature inside the transformer, can maintain the integrity of encapsulation for a long time.
[0054] In addition, the epoxy material is easy to be molded and can closely fit the shapes of the first single-mode optical fiber 100, the second single-mode optical fiber 300 and the multi-mode optical fiber 200, thereby ensuring the firm connection between the packaging protective shell 400 and the optical fibers, not interfering with the transmission of ultrasonic waves by the sound transmission hole 500 and the normal operation of the Fabry-Perot interference cavity, and further improving the insulation reliability, environmental adaptability and structural durability of the sensor.
[0055] The technical features of the above embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictions, they shall be considered as the scope of the present disclosure.
[0056] The above embodiments only express several implementation manners of the present application, and the description is specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that for those skilled in the art, some modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application shall be subject to the appended claims.
Claims
1. An SMS-structured Fabry-Perot ultrasonic sensor, characterized in that, The SMS structure Fabry-Perot ultrasonic sensor includes: A first single-mode fiber (100), a multimode fiber (200), and a second single-mode fiber (300) are sequentially arranged and fused together. The fusion areas of the first single-mode fiber (100), the multimode fiber (200), the second single-mode fiber (300), and the multimode fiber (200) respectively form reflective end faces to construct a Fabry-Perot interferometer cavity. The cavity length of the Fabry-Perot interferometer cavity is the length of the multimode fiber (200). A protective enclosure (400) covers the multimode optical fiber (200) and the two fusion splice areas, and is connected to the first single-mode optical fiber (100) and the second single-mode optical fiber (300); the protective enclosure (400) is provided with a sound transmission hole (500).
2. The SMS-structured Fabry-Perot ultrasonic sensor according to claim 1, characterized in that, The encapsulation protective shell (400) includes a shell (410) and an end plate (420) disposed at one end of the shell (410). The shell (410) covers the multimode optical fiber (200) and two fusion splicing areas, and the end plate (420) abuts against the second single-mode optical fiber (300). The end plate (420) is provided with the sound transmission hole (500).
3. The SMS structure Fabry-Perot ultrasonic sensor according to claim 2, characterized in that, The sound transmission holes (500) are provided in multiple ways, and the multiple sound transmission holes (500) are arranged at intervals around the arrangement direction of the first single-mode fiber (100), the multimode fiber (200) and the second single-mode fiber (300).
4. The SMS structure Fabry-Perot ultrasonic sensor according to claim 1, characterized in that, The encapsulation protective shell (400) is connected to the first single-mode optical fiber (100) and the second single-mode optical fiber (300) by chemical bonding.
5. The SMS structure Fabry-Perot ultrasonic sensor according to claim 1, characterized in that, The length of the multimode optical fiber (200) is 50μm-1000μm.
6. The SMS-structured Fabry-Perot ultrasonic sensor according to claim 1, characterized in that, The first single-mode fiber (100) includes a first single-mode fiber core (110) and a first single-mode cladding (120), wherein the first single-mode cladding (120) wraps the first single-mode fiber core (110).
7. The SMS structure Fabry-Perot ultrasonic sensor according to claim 6, characterized in that, The second single-mode fiber (300) includes a second single-mode fiber core (310) and a second single-mode cladding (320), wherein the second single-mode cladding (320) wraps around the second single-mode fiber core (310).
8. The SMS structure Fabry-Perot ultrasonic sensor according to claim 7, characterized in that, The diameter of the first single-mode fiber core (110) and / or the second single-mode fiber core (310) is 9 μm, and the diameter of the first single-mode cladding (120) and / or the second single-mode cladding (320) is 125 μm.
9. The SMS structure Fabry-Perot ultrasonic sensor according to claim 1, characterized in that, The multimode fiber (200) includes a multimode core (210) and a multimode cladding (220), wherein the multimode cladding (220) encloses the multimode core (210), the multimode core (210) has a diameter of 50 μm, and the multimode cladding (220) has a diameter of 125 μm.
10. The SMS structure Fabry-Perot ultrasonic sensor according to claim 1, characterized in that, The protective casing (400) is made of epoxy resin material.