A reflective optical fiber displacement sensing system and its preparation method

Abstract

A reflective fiber optic displacement sensing system includes a transmitting optical fiber, a receiving optical fiber, a long sleeve, and an outer sleeve. The corresponding pre-transmitting bare optical fibers (PBEs) on the transmitting and receiving optical fibers are closely adjacent to each other, their sides coated with a common resin layer, which is then coated with a long sleeve. The outer sleeve is located near the end faces of the long sleeve. The bottom of the outer sleeve is a reflective surface, which is positioned opposite the end faces of the PBEs and the PBEs, forming a displacement cavity between the reflective surface and the end faces. The diameter of the outer sleeve is larger than that of the long sleeve, and a sleeve gap is formed between the inner wall of the outer sleeve and the outer wall of the long sleeve. This design is not only compact and simple in structure, but also highly efficient and stable.

Description

Technical Field

[0001] The present invention relates to an optical fiber sensing device, belongs to the field of optical sensor devices, and in particular to a reflective optical fiber displacement sensing system and a preparation method thereof. Background Art

[0002] Currently, fiber optic sensors are generally categorized into two types: functional (or sensing) and non-functional (light-transmitting) based on the role the optical fiber plays within the sensor. Functional fiber optic sensors typically use single-mode optical fiber, which not only transmits light but also serves as the sensor's sensitive element. However, these sensors are technically challenging to manufacture, have complex structures, and are difficult to debug. Non-functional fiber optic sensors, on the other hand, contain optical fibers that only transmit light and are not the sensor's sensitive element. These sensors are characterized by their simple and reliable structure, ease of technical implementation, and ease of application.

[0003] With the development of fiber optic technology, various fiber optic sensors have emerged, such as displacement sensors. However, existing displacement sensors have the defects of large size and complex structure, which seriously limit the application of optical fiber in the field of displacement measurement.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of this patent application, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects and problems of the prior art such as large volume and complex structure, and to provide a reflective optical fiber displacement sensing system with small volume and simple structure and a preparation method thereof.

[0006] To achieve the above objectives, the technical solution of the present invention is: a reflective optical fiber displacement sensing system, comprising a transmitting optical fiber and a receiving optical fiber, wherein the input end of the transmitting optical fiber is connected to a light source, and the output end of the receiving optical fiber is connected to a photodetector;

[0007] The transmitting optical fiber near its output end is a bare optical fiber before transmission, and the receiving optical fiber near its input end is a bare optical fiber before reception. The bare optical fiber before transmission and the bare optical fiber before reception are arranged side by side, and the bottom side of the bare optical fiber before transmission and the top side of the bare optical fiber before reception are in contact with each other;

[0008] The outer sides of the bare optical fiber before transmitting and the bare optical fiber before receiving are both wrapped with the same resin layer, and the outer sides of the resin layer are wrapped with a long sleeve, and the front end surfaces of the bare optical fiber before transmitting, the bare optical fiber before receiving, and the long sleeve are all flush with each other;

[0009] An outer sleeve is arranged on the portion of the long sleeve near its first end face, and the bottom of the outer sleeve is a reflecting surface, which is arranged opposite to the first end faces of the bare optical fiber before transmission and the bare optical fiber before reception, and a displacement cavity is formed between the reflecting surface and the first end faces. The diameter of the outer sleeve is larger than the diameter of the long sleeve, and a sleeve gap is formed between the inner sleeve wall of the outer sleeve and the outer sleeve wall of the long sleeve.

[0010] The outside of the side of the bare optical fiber before transmitting and the bare optical fiber before receiving are both wrapped with the same adhesive tape layer, and the outside of the adhesive tape layer is wrapped with a resin layer.

[0011] The resin layer is made of epoxy resin.

[0012] A short sleeve is provided on the long sleeve near its tail end surface. One end of the short sleeve is sleeved on the long sleeve, and the other end of the short sleeve is sleeved on the transmitting optical fiber and the receiving optical fiber. The bare optical fiber before transmitting and the bare optical fiber before receiving are both arranged inside the long sleeve.

[0013] The gaps between the short sleeve and the long sleeve, the transmitting optical fiber and the receiving optical fiber are all filled with epoxy resin.

[0014] The long sleeve, the short sleeve and the outer sleeve are all made of opaque metal.

[0015] The structure of the reflective surface is any one of the following:

[0016] A reflective film is provided on one surface of the bottom of the outer sleeve close to the long sleeve;

[0017] A layer of metal aluminum powder is coated on the side of the outer sleeve bottom near the long sleeve;

[0018] The bottom of the outer sleeve is an embedded ABS material disc, and the side of the ABS material disc close to the long sleeve is polished or coated with a reflective film.

[0019] The portion of the transmitting optical fiber near its input end is the transmitting bare optical fiber, and the portion of the receiving optical fiber near its output end is the receiving bare optical fiber. The transmitting bare optical fiber and the receiving bare optical fiber are both inserted into the interior of the ABS connector. Epoxy resin is filled between the side walls of the transmitting bare optical fiber and the receiving bare optical fiber and the inner wall of the ABS connector. The outer portions of the transmitting optical fiber and the receiving optical fiber near the ABS connector are covered with the same tail sleeve, and epoxy resin is filled between the tail sleeve and the transmitting optical fiber and the receiving optical fiber.

[0020] A method for preparing the above-mentioned reflective optical fiber displacement sensing system comprises the following steps:

[0021] Step 1: First, place the bare optical fiber before transmission and the bare optical fiber before reception side by side and close together, then apply liquid resin on the side of the bare optical fiber before transmission and the bare optical fiber before reception, and then insert the bare optical fiber before transmission and the bare optical fiber before reception with resin into the long sleeve until the head end of the bare optical fiber before transmission and the bare optical fiber before reception pass through the head end face of the long sleeve. After the resin is solidified, the part of the bare optical fiber before transmission and the bare optical fiber before reception that passes through the head end face of the long sleeve is subjected to coarse grinding, fine grinding, polishing, and alcohol cleaning in sequence;

[0022] Step 2: First, select the outer sleeve. The outer sleeve is a cylindrical structure with an open structure at the left end and a reflective surface at the right end. The setting method is any of the following:

[0023] The right end of the outer sleeve is a sealed structure, and a reflective film is attached or plated on the inner side surface of the right end of the outer sleeve;

[0024] The right end of the outer sleeve is an open structure, and an ABS material disc is embedded in the right end of the outer sleeve. The side of the ABS material disc close to the long sleeve is polished or coated with a reflective film;

[0025] Step 3: Insert the first end of the long sleeve in the first step into the outer sleeve through the left end of the outer sleeve until the first end of the long sleeve is facing the reflecting surface and clamped into a displacement cavity.

[0026] In the first step, the bare optical fiber before transmission and the bare optical fiber before reception are placed side by side and close to each other, and then at least three layers of raw tape are wrapped around the side of the bare optical fiber before transmission and the bare optical fiber before reception to obtain a tape layer, and then a fluid resin is applied to the side of the tape layer.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention relates to a reflective fiber optic displacement sensing system and its preparation method, which primarily comprises a transmitting optical fiber, a receiving optical fiber, a long sleeve, and an outer sleeve. The transmitting and receiving optical fibers, located within the long sleeve, are bare optical fibers. The head end faces of the bare optical fibers are flush with the head end faces of the long sleeve and are located together within the outer sleeve, forming a displacement cavity between the bare optical fibers and the reflective surface within the outer sleeve. During operation, light emitted by a light source through the transmitting optical fiber is first directed toward the transmitting surface, then reflected by the reflective surface before entering the receiving optical fiber. The receiving optical fiber then transmits the received reflected light to a photodetector for signal processing. The distance / displacement from the optical fiber end face to the measured reflective surface is measured based on the intensity of the detected reflected light. This system is highly convenient, fast, and accurate. Furthermore, the transmitting optical fiber, receiving optical fiber, long sleeve, and outer sleeve are all compact, making them easy to carry and assemble, and suitable for a wide range of applications. Therefore, the present invention is not only compact but also has a simple structure.

[0029] 2. In a reflective fiber optic displacement sensing system and its preparation method, the exterior of the side surfaces of the pre-transmitting bare optical fiber and the pre-receiving bare optical fiber can be first wrapped with a common tape layer, and then the exterior of the tape layer is wrapped with a resin layer made of epoxy resin. This design not only secures the pre-transmitting bare optical fiber and the pre-receiving bare optical fiber within the long sleeve, but also utilizes the epoxy resin's ability to switch between liquid and solid states, facilitating the fabrication of the sensing system and ensuring stability after fabrication. Therefore, the present invention not only has high fabrication efficiency but also strong stability.

[0030] 3. In the present invention, a reflective fiber optic displacement sensing system and its preparation method are described. To manufacture the sensing system, the transmitting fiber, receiving fiber, and long sleeve are first assembled, and then inserted into the outer sleeve to form the present design. Furthermore, the other ends of the transmitting and receiving fibers can be further designed, such as by integrating them with ABS connectors to form jumper terminals, thereby improving stability and convenience during use. Therefore, the present invention not only has high manufacturing efficiency but also has excellent application effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention.

[0032] Figure 2 yes Figure 1 Schematic diagram of the connection between the ABS connector and the transmitting optical fiber.

[0033] Figure 3 yes Figure 1 Schematic diagram of the connection between the ABS connector and the receiving optical fiber.

[0034] Figure 4 yes Figure 1 Cross-sectional view of a medium-length casing.

[0035] Figure 5 It is a schematic diagram of the assembly of the transmitting optical fiber, the receiving optical fiber, the long sleeve and the short sleeve in the present invention.

[0036] Figure 6 It is a schematic diagram of the production of the outer sleeve in the present invention.

[0037] In the figure: long sleeve 1, short sleeve 2, outer sleeve 3, reflecting surface 31, displacement cavity 32, sleeve gap 33, ABS material wafer 34, transmitting optical fiber 4, bare optical fiber before transmission 41, bare optical fiber after transmission 42, receiving optical fiber 5, bare optical fiber before reception 51, bare optical fiber after reception 52, resin layer 6, tape layer 7, ABS connector 8, tail sleeve 9, light source 10, photodetector 11, head end face X, tail end face Y. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] See also Figure 1 — Figure 6 , a reflective optical fiber displacement sensing system, comprising a transmitting optical fiber 4 and a receiving optical fiber 5, wherein the input end of the transmitting optical fiber 4 is connected to a light source 10, and the output end of the receiving optical fiber 5 is connected to a photodetector 11;

[0040] The transmitting optical fiber 4 is provided with a bare optical fiber 41 near its output end, and the receiving optical fiber 5 is provided with a bare optical fiber 51 near its input end. The bare optical fiber 41 is provided with a bare optical fiber 51 near its input end. The bare optical fiber 41 is provided with a bare optical fiber 51 and the bare optical fiber 51 is provided with a bare optical fiber 51. The bottom side of the bare optical fiber 41 is in contact with the top side of the bare optical fiber 51. The bare optical fiber 41 is provided with a bare optical fiber 51 and the bare optical fiber 51 is provided with a bare optical fiber 51.

[0041] The outer sides of the bare optical fiber before transmitting 41 and the bare optical fiber before receiving 51 are both wrapped with the same resin layer 6, and the outer side of the resin layer 6 is wrapped with a long sleeve 1. The front end faces X of the bare optical fiber before transmitting 41, the bare optical fiber before receiving 51, and the long sleeve 1 are all flush with each other;

[0042] An outer sleeve 3 is provided on the long sleeve 1 near its first end face X. The bottom of the outer sleeve 3 is a reflecting surface 31. The reflecting surface 31 is arranged opposite to the first end face X of the bare optical fiber 41 before transmitting and the bare optical fiber 51 before receiving. A displacement cavity 32 is formed between the reflecting surface 31 and the first end face X. The diameter of the outer sleeve 3 is larger than the diameter of the long sleeve 1. A sleeve gap 33 is formed between the inner sleeve wall of the outer sleeve 3 and the outer sleeve wall of the long sleeve 1.

[0043] The outside of the side of the bare optical fiber before transmission 41 and the bare optical fiber before reception 51 is wrapped with the same tape layer 7, and the outside of the tape layer 7 is wrapped with a resin layer 6.

[0044] The resin layer 6 is made of epoxy resin.

[0045] A short sleeve 2 is provided on the long sleeve 1 near its tail end surface Y. One end of the short sleeve 2 is sleeved on the long sleeve 1, and the other end of the short sleeve 2 is sleeved on the transmitting optical fiber 4 and the receiving optical fiber 5. The bare optical fiber 41 before transmitting and the bare optical fiber 51 before receiving are both arranged inside the long sleeve 1.

[0046] The gaps between the short sleeve 2 and the long sleeve 1 , the transmitting optical fiber 4 , and the receiving optical fiber 5 are all filled with epoxy resin.

[0047] The long sleeve 1, the short sleeve 2 and the outer sleeve 3 are all made of opaque metal.

[0048] The structure of the reflecting surface 31 is any one of the following:

[0049] A reflective film is provided on the bottom of the outer sleeve 3 on one side close to the long sleeve 1;

[0050] A layer of metal aluminum powder is coated on one side of the bottom of the outer sleeve 3 near the long sleeve 1;

[0051] The bottom of the outer sleeve 3 is an embedded ABS disc 34 , and the side of the ABS disc 34 close to the long sleeve 1 is polished or coated with a reflective film.

[0052] The portion of the transmitting optical fiber 4 near its input end is the transmitting bare optical fiber 42, and the portion of the receiving optical fiber 5 near its output end is the receiving bare optical fiber 52. The transmitting bare optical fiber 42 and the receiving bare optical fiber 52 are both inserted into the interior of the ABS connector 8, and epoxy resin is filled between the side walls of the transmitting bare optical fiber 42 and the receiving bare optical fiber 52 and the inner wall of the ABS connector 8. The outer portion of the transmitting optical fiber 4 and the receiving optical fiber 5 near the ABS connector 8 is provided with the same tail sleeve 9, and epoxy resin is filled between the tail sleeve 9 and the transmitting optical fiber 4 and the receiving optical fiber 5.

[0053] A method for preparing the above-mentioned reflective optical fiber displacement sensing system comprises the following steps:

[0054] Step 1: First, place the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 side by side and close together, then apply liquid resin on the side of the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51, and then insert the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 with resin into the long sleeve 1 until the head end of the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 passes through the head end surface X of the long sleeve 1. After the resin is cured, the parts of the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 that pass through the head end surface X of the long sleeve 1 are sequentially subjected to coarse grinding, fine grinding, polishing, and alcohol cleaning;

[0055] Step 2: First, select the outer sleeve 3. The outer sleeve 3 is a cylindrical structure. The left end of the outer sleeve 3 is an open structure. The right end of the outer sleeve 3 is provided with a reflective surface 31. The setting method is any one of the following:

[0056] The right end of the outer sleeve 3 is a sealed structure, and a reflective film is attached or plated on the inner side surface of the right end of the outer sleeve 3;

[0057] The right end of the outer sleeve 3 is an open structure, and an ABS material disc 34 is embedded in the right end of the outer sleeve 3. The side of the ABS material disc 34 close to the long sleeve 1 is polished or coated with a reflective film;

[0058] Step 3: Insert the first end face X of the long sleeve 1 in the first step into the outer sleeve 3 through the left end face of the outer sleeve 3 until the first end face X of the long sleeve 1 is opposite to the reflecting surface 31 and a displacement cavity 32 is formed.

[0059] In the first step, the bare optical fiber before transmission 41 and the bare optical fiber before reception 51 are first placed side by side and close to each other, and then at least three layers of raw tape are wrapped around the side of the bare optical fiber before transmission 41 and the bare optical fiber before reception 51 to obtain a tape layer 7, and then a fluid resin is applied to the side of the tape layer 7.

[0060] The principle of the present invention is described as follows:

[0061] The transmitting optical fiber and the receiving optical fiber in the present invention have the same structure, which are a core, a coating or a sheath, and an outer protective layer from the inside to the outside. The core and the coating together constitute a bare optical fiber, and the outer protective layer is often called a sheath.

[0062] The transmitting optical fiber and the receiving optical fiber in the present invention are preferably communication-grade plastic optical fibers. Communication-grade plastic optical fibers (POF) are a type of optical fiber (optical fiber) made of polymethyl methacrylate (PMMA) or polycarbonate (PC) as core materials and PMMA, fluoroplastics, etc. as sheath materials.

[0063] The ABS material in the present invention refers to acrylonitrile-butadiene-styrene copolymer, also known as ABS resin. It is a thermoplastic polymer material with high strength, good toughness, and easy processing and molding. ABS plastic is a terpolymer of acrylonitrile (A), butadiene (B), and styrene (S). The relative content of the three monomers can be arbitrarily varied to produce a variety of resins. In the present invention, ABS material has a good thermal expansion coefficient, which is consistent between -10°C and 80°C, and does not affect the reflective effect of the reflective film.

[0064] Example 1:

[0065] See also Figure 1 — Figure 6A reflective optical fiber displacement sensing system includes a transmitting optical fiber 4 and a receiving optical fiber 5. The input end of the transmitting optical fiber 4 is connected to a light source 10, and the output end of the receiving optical fiber 5 is connected to a photodetector 11. The transmitting optical fiber 4 is near its output end and is a pre-transmitting bare optical fiber 41. The receiving optical fiber 5 is near its input end and is a pre-receiving bare optical fiber 51. The pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 are arranged side by side, and the bottom side of the pre-transmitting bare optical fiber 41 is in contact with the top side of the pre-receiving bare optical fiber 51. The outer sides of the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 are both covered with It is wrapped with the same resin layer 6, and the outside of the resin layer 6 is wrapped with a long sleeve 1. The bare optical fiber 41 before transmission, the bare optical fiber 51 before reception, and the first end face X of the long sleeve 1 are all flush with each other; the long sleeve 1 is covered with an outer sleeve 3 near its first end face X, and the bottom of the outer sleeve 3 is a reflecting surface 31, which is arranged opposite to the first end face X of the bare optical fiber 41 before transmission and the bare optical fiber 51 before reception. A displacement cavity 32 is formed between the reflecting surface 31 and the first end face X. The diameter of the outer sleeve 3 is larger than the diameter of the long sleeve 1, and a sleeve gap 33 is sandwiched between the inner tube wall of the outer sleeve 3 and the outer tube wall of the long sleeve 1.

[0066] A method for preparing the above-mentioned reflective optical fiber displacement sensing system comprises the following steps:

[0067] Step 1: First, place the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 side by side and close together, then apply liquid resin on the side of the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51, and then insert the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 with resin into the long sleeve 1 until the head end of the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 passes through the head end surface X of the long sleeve 1. After the resin is cured, the parts of the pre-transmitting bare optical fiber 41 and the pre-receiving bare optical fiber 51 that pass through the head end surface X of the long sleeve 1 are sequentially subjected to coarse grinding, fine grinding, polishing, and alcohol cleaning;

[0068] Step 2: First, select the outer sleeve 3. The outer sleeve 3 is a cylindrical structure. The left end of the outer sleeve 3 is an open structure. The right end of the outer sleeve 3 is provided with a reflective surface 31. The setting method is any one of the following:

[0069] The right end of the outer sleeve 3 is a sealed structure, and a reflective film is attached or plated on the inner side surface of the right end of the outer sleeve 3;

[0070] The right end of the outer sleeve 3 is an open structure, and an ABS material disc 34 is embedded in the right end of the outer sleeve 3. The side of the ABS material disc 34 close to the long sleeve 1 is polished or coated with a reflective film;

[0071] Step 3: Insert the first end face X of the long sleeve 1 in the first step into the outer sleeve 3 through the left end face of the outer sleeve 3 until the first end face X of the long sleeve 1 is opposite to the reflecting surface 31 and a displacement cavity 32 is formed.

[0072] Example 2:

[0073] The basic content is the same as Example 1, except that:

[0074] Structurally, the outer sides of the bare optical fiber before transmission 41 and the bare optical fiber before reception 51 are both wrapped with a same adhesive tape layer 7 , and the outer side of the adhesive tape layer 7 is wrapped with a resin layer 6 .

[0075] Preparation method: In the first step, the bare optical fiber 41 before transmission and the bare optical fiber 51 before reception are placed side by side and close to each other, and then at least three layers of raw tape are wrapped around the side of the bare optical fiber 41 before transmission and the bare optical fiber 51 before reception to obtain a tape layer 7, and then a fluid resin is applied to the side of the tape layer 7.

[0076] Example 3:

[0077] The basic content is the same as Example 1, except that the specific steps of the first step are as follows:

[0078] First, strip off about 5.5cm of the black sheath on the output end of the transmitting optical fiber 4 and the input end of the receiving optical fiber 5 to obtain the bare optical fiber 41 before transmitting and the bare optical fiber 51 before receiving. Pay attention to check whether the bare optical fiber leaks light. If it leaks light, strip off the black sheath again, then put the bare optical fiber 41 before transmitting and the bare optical fiber 51 before receiving close together, and then wrap 3-5 layers of white raw tape on the surface of the two bare optical fibers (constituting the tape layer 7) and then evenly apply a layer of epoxy resin glue (constituting the resin layer 6), and then pass it through the long sleeve 1 (inner diameter 2.9mm, outer diameter 3mm, length 50mm) and expose about 5mm, and then in the long sleeve 1 (inner diameter 2.9mm, outer diameter 3mm, length 50mm) A layer of epoxy resin glue about 1.5 cm long is evenly coated on the outer surfaces of the sleeve 1, the transmitting optical fiber 4, and the receiving optical fiber 5. Then, a short sleeve 2 with a length of 1.5 m, an inner diameter of 4.5 mm, and an outer diameter of 4.6 mm is put on the glue-dotting section of the long sleeve 1, the transmitting optical fiber 4, and the receiving optical fiber 5. The gap in the short sleeve 2 is filled with epoxy resin glue, and then left to stand for 24 hours to wait for the epoxy resin glue to solidify. Then, the bare optical fiber exposed on the left side of the long sleeve 1 on the bare optical fiber before transmission 41 and the bare optical fiber before receiving 51 is processed according to the procedures and processes of rough grinding, fine grinding, and polishing, and then the polished end face is cleaned with alcohol and then covered with a plastic cap.

[0079] Example 4:

[0080] The basic content is the same as Example 1, except that:

[0081] Structurally: the portion of the transmitting optical fiber 4 near its input end is the bare optical fiber 42 after transmission, and the portion of the receiving optical fiber 5 near its output end is the bare optical fiber 52 after reception. The bare optical fiber 42 after transmission and the bare optical fiber 52 after reception are both inserted into the interior of the ABS connector 8. The side surfaces of the bare optical fiber 42 after transmission and the bare optical fiber 52 after reception and the inner wall of the ABS connector 8 are filled with epoxy resin. The outer portion of the portion of the transmitting optical fiber 4 and the receiving optical fiber 5 near the ABS connector 8 is provided with the same tail sleeve 9, and the tail sleeve 9 and the transmitting optical fiber 4 and the receiving optical fiber 5 are filled with epoxy resin.

[0082] Preparation method: First, strip off the black sheath of the transmitting optical fiber 4 and the receiving optical fiber 5 by about 1.5 cm each to obtain the transmitting bare optical fiber 42 and the receiving bare optical fiber 52. Pay attention to check whether the bare optical fiber is leaking. If it is leaking, strip off a section of the black sheath of about 1.5 cm again, and then evenly apply a layer of epoxy resin glue on the surface of the transmitting bare optical fiber 42 and the receiving bare optical fiber 52. Then insert it from the right side of the ABS connector 8, and then pass it out from the inner hole on the left side with about 2-3 mm exposed. Then, about 3 cm on the right side of the ABS connector 8 A layer of epoxy resin glue is evenly coated on the surface of the m-long transmitting optical fiber 4 and the receiving optical fiber 5, and then a cylindrical steel tube with a length of 3 cm, an inner diameter of 2.9 mm and an outer diameter of 3 mm (i.e., the tail sleeve 9) is used to cover the optical fiber with the epoxy resin glue coated on the outer surface. After standing for 24 hours to wait for the epoxy resin glue to solidify, the exposed parts of the transmitting bare optical fiber 42 and the receiving bare optical fiber 52 on the left side of the ABS connector 8 are processed according to the procedures and processes of rough grinding, fine grinding, and polishing, and then the polished end faces are cleaned with alcohol, and then covered with plastic caps.

[0083] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed in the present invention should be included in the protection scope recorded in the claims.

Claims

1. A reflective optical fiber displacement sensing system, comprising a transmitting optical fiber (4) and a receiving optical fiber (5), wherein the input end of the transmitting optical fiber (4) is connected to a light source (10), and the output end of the receiving optical fiber (5) is connected to a photodetector (11), characterized in that: The transmitting optical fiber (4) is provided with a bare optical fiber before transmission (41) near its output end, and the receiving optical fiber (5) is provided with a bare optical fiber before reception (51) near its input end. The bare optical fiber before transmission (41) and the bare optical fiber before reception (51) are arranged side by side, and the bottom side of the bare optical fiber before transmission (41) and the top side of the bare optical fiber before reception (51) are in contact with each other. The outer sides of the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) are both wrapped with the same resin layer (6), and the outer side of the resin layer (6) is wrapped with a long sleeve (1), and the front end faces (X) of the bare optical fiber before transmission (41), the bare optical fiber before reception (51), and the long sleeve (1) are all flush with each other; An outer sleeve (3) is provided on the portion of the long sleeve (1) near its first end face (X), and the bottom of the outer sleeve (3) is a reflecting surface (31). The reflecting surface (31) is arranged opposite to the first end face (X) of the bare optical fiber (41) before transmitting and the bare optical fiber (51) before receiving, and a displacement cavity (32) is formed between the reflecting surface (31) and the first end face (X). The diameter of the outer sleeve (3) is larger than the diameter of the long sleeve (1), and a sleeve gap (33) is formed between the inner sleeve wall of the outer sleeve (3) and the outer sleeve wall of the long sleeve (1); The outer sides of the bare optical fiber before transmitting (41) and the bare optical fiber before receiving (51) are both wrapped with a same adhesive tape layer (7), and the outer side of the adhesive tape layer (7) is wrapped with a resin layer (6); the resin layer (6) is made of epoxy resin; The structures of the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) are both a fiber core and a coating layer wrapped around the outside; The pre-emitting bare optical fiber (41) and the pre-receiving bare optical fiber (51) are close to each other; The application process of the above-mentioned reflective optical fiber displacement sensing system includes: the light emitted by the light source (10) through the transmitting optical fiber (4) is first emitted to the reflecting surface (31), and then after being reflected by the reflecting surface (31), it enters the receiving optical fiber (5), and then the receiving optical fiber (5) sends the received reflected light to the photoelectric detector (11) for signal processing, so as to measure the distance / displacement size from the head end face (X) to the measured reflecting surface (31) according to the intensity of the detected reflected light.

2. The reflective optical fiber displacement sensing system according to claim 1, characterized in that: A short sleeve (2) is provided on the long sleeve (1) near its tail end surface (Y), one end of the short sleeve (2) is sleeved on the long sleeve (1), and the other end of the short sleeve (2) is sleeved on the transmitting optical fiber (4) and the receiving optical fiber (5), and the bare optical fiber before transmitting (41) and the bare optical fiber before receiving (51) are both arranged inside the long sleeve (1).

3. The reflective optical fiber displacement sensing system according to claim 2, wherein: The gaps between the short sleeve (2) and the long sleeve (1), the transmitting optical fiber (4), and the receiving optical fiber (5) are all filled with epoxy resin.

4. The reflective optical fiber displacement sensing system according to claim 2, wherein: The long sleeve (1), the short sleeve (2), and the outer sleeve (3) are all made of opaque metal.

5. The reflective optical fiber displacement sensing system according to claim 1, wherein: The structure of the reflecting surface (31) is any one of the following: A reflective film is provided on one surface of the bottom of the outer sleeve (3) near the long sleeve (1); A layer of metal aluminum powder is coated on one side of the bottom of the outer sleeve (3) near the long sleeve (1); The bottom of the outer sleeve (3) is an embedded ABS material disc (34), and the side of the ABS material disc (34) close to the long sleeve (1) is polished or coated with a reflective film.

6. The reflective optical fiber displacement sensing system according to claim 1, characterized in that: The portion of the transmitting optical fiber (4) near its input end is the transmitting bare optical fiber (42), and the portion of the receiving optical fiber (5) near its output end is the receiving bare optical fiber (52). The transmitting bare optical fiber (42) and the receiving bare optical fiber (52) are both inserted into the interior of the ABS connector (8). The side walls of the transmitting bare optical fiber (42) and the receiving bare optical fiber (52) and the inner wall of the ABS connector (8) are filled with epoxy resin. The outer portions of the transmitting optical fiber (4) and the receiving optical fiber (5) near the ABS connector (8) are provided with the same tail sleeve (9), and the tail sleeve (9) and the transmitting optical fiber (4) and the receiving optical fiber (5) are filled with epoxy resin.

7. A method for preparing the reflective optical fiber displacement sensing system according to claim 1, characterized in that: The preparation method comprises the following steps: The first step: first, place the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) side by side and close together, then apply liquid resin on the side of the bare optical fiber before transmission (41) and the bare optical fiber before reception (51), and then insert the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) with resin into the long sleeve (1) until the head end of the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) pass through the head end face (X) of the long sleeve (1), and after the resin is solidified, the part of the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) that passes through the head end face (X) of the long sleeve (1) is subjected to coarse grinding, fine grinding, polishing, and alcohol cleaning in sequence; Step 2: First, select an outer sleeve (3). The outer sleeve (3) is a cylindrical structure. The left end of the outer sleeve (3) is an open structure. The right end of the outer sleeve (3) is provided with a reflective surface (31). The setting method is any one of the following: The right end of the outer sleeve (3) is a sealing structure, and a reflective film is attached or plated on the inner side surface of the right end of the outer sleeve (3); The right end of the outer sleeve (3) is an open structure, and an ABS material disc (34) is embedded in the right end of the outer sleeve (3), and the side of the ABS material disc (34) close to the long sleeve (1) is polished or coated with a reflective film; Step 3: Insert the first end face (X) of the long sleeve (1) in the first step into the outer sleeve (3) through the left end face of the outer sleeve (3) until the first end face (X) of the long sleeve (1) is aligned with the reflective surface (31) and a displacement cavity (32) is formed.

8. The method for preparing a reflective optical fiber displacement sensing system according to claim 7, wherein: In the first step, the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) are placed side by side and close to each other, and then at least three layers of raw tape are wrapped around the side of the bare optical fiber before transmission (41) and the bare optical fiber before reception (51) to obtain a tape layer (7), and then a fluid resin is applied to the side of the tape layer (7).

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