A fiber-coupled monitoring device and a method of designing the same

Abstract

The present application relates to the technical field of pollution monitoring, and particularly relates to a fiber coupling monitoring device and a design method thereof. The present application utilizes the characteristic that petroleum and other substances will reflect fluorescence under the irradiation of excitation light. The excitation light is transmitted through an optical fiber and then reflected by a concave mirror. The excitation light is distributed on the surface of underground water. When the underground water is polluted by petroleum, the pollutants will reflect fluorescence after being irradiated by the excitation light. The fluorescence is coupled into the optical fiber after being reflected and converged by the concave mirror. The fluorescence is transmitted through the optical fiber to a spectrometer. The spectrometer decomposes the fluorescence into different wave bands after receiving the fluorescence. Whether the fluorescence contains specific fluorescent substances and the content of the specific fluorescent substances are determined according to characteristic spectral lines. The present application can monitor whether oil and gas leakage occurs in underground water in real time. The present application eliminates the complex process of sampling in a water quality monitoring hole. Even if small-scale oil and gas leakage occurs, small oil films will be formed on the surface of underground water to reflect fluorescence. The progress of monitoring of pollutants in underground water is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pollution monitoring, and particularly relates to a fiber coupling monitoring device and a design method thereof. BACKGROUND

[0002] The underground water-sealed cavern is used to form a water pressure barrier by using the underground water level, so as to prevent oil and gas leakage in the cavern. However, if the oil height exceeds the water level or the surrounding rock fissures develop, the oil may seep into the rock mass and pollute the underground water.

[0003] At present, the underground water oil pollution monitoring mainly relies on manual sampling and laboratory analysis. For the detection of the oil concentration in the underground water, the traditional method mainly adopts the mass method to analyze the water sample after sampling, for example, water quality monitoring holes are arranged around the underground water-sealed cavern, a PVC sleeve and a screen pipe are installed in the hole to filter the water sample. However, due to the characteristics of the water quality monitoring hole in the underground water-sealed cavern, such as deep hole depth, small hole diameter and the like, the technical personnel regularly extracts the water sample from the water quality monitoring hole by using a bailer or a submersible pump, and the sampling difficulty in the hole is relatively large. At the same time, due to the dispersed distribution of the hole positions, the manual observation is not convenient. The water sample is sent to the laboratory to detect the total oil hydrocarbon concentration by the gas chromatography method or the ultraviolet fluorescence method, and the oil concentration detection process is relatively complex. The traditional method is time-consuming and has low spatial resolution, and it is difficult to capture small-range leakage. SUMMARY

[0004] The main purpose of the present application is to provide a fiber coupling monitoring device and a design method thereof, so as to solve the technical problems of the traditional underground water oil pollution monitoring method, such as sampling difficulty, long time consumption and difficulty in capturing small-range oil leakage.

[0005] To achieve the above-mentioned purpose, the present application provides a fiber coupling monitoring device, which comprises a light source, an optical fiber, a ferrule, a spectrometer and a concave mirror, wherein:

[0006] The optical fiber is in a Y-shaped structure, and comprises a first end, a second end and a third end. The first end and the second end are oppositely arranged on the two sides of the first end. The second end and the third end are both arranged away from the ferrule. The first end is fixedly connected with the ferrule.

[0007] The light source is used for emitting excitation light, and the light source is opposite to the end face of the second end.

[0008] The ferrule has an inner hole extending along the extension direction of the ferrule. The first end is fixed in the inner hole, and the end face of the first end is exposedly arranged from the inner hole.

[0009] The spectrometer is used for receiving the fluorescence reflected by the pollutants and analyzing the spectrum of the fluorescence. The third end is connected with the spectrometer.

[0010] The mirror surface of the concave mirror is arranged corresponding to the end surface of the first end.

[0011] Further, the end surface of the first end deviates from the plane where the optical axis of the concave mirror is located, so that the excitation light is not reflected back to the first end after being emitted.

[0012] Further preferably, the fluorescence is converged to form a light spot after being reflected by the concave mirror, the diameter of the light spot is the same as the diameter of the end surface of the first end, and the end surface of the first end is located at the position of the light spot.

[0013] Further preferably, the first end of the optical fiber is provided with a first branch and a second branch, the first branch is connected with the second end, and the second branch is connected with the third end, and the ends of the fiber cores in the first branch and the second branch are uniformly distributed on the end surface of the first end.

[0014] Further preferably, the concave mirror comprises a first edge line and a second edge line, the first edge line and the second edge line are located at both ends of the bending direction of the concave mirror, the first edge line is away from the ferrule, the second edge line is close to the ferrule, and the arc length of the cross-sectional circle arc between the first edge line and the second edge line is less than 1 / 4 of the arc length of the circle where the cross-sectional circle arc is located.

[0015] Further, the coupling assembly comprises a light collecting port, a mounting groove and a ferrule hole, the mounting groove and the ferrule hole are located on both sides of the light collecting port, the mounting groove and the ferrule hole are opposite, the ferrule is fixed in the ferrule hole, the end surface of the first end faces the concave mirror, the concave mirror is fixed in the mounting groove, and the optical axis of the concave mirror is inclined to the outside of the light collecting port.

[0016] The application also provides a design method of an optical fiber coupling monitoring device, which is applied to the optical fiber coupling monitoring device and comprises the following steps:

[0017] S1, obtaining the optical axis of the concave mirror; wherein the optical axis is arranged obliquely relative to the horizontal plane;

[0018] S2, obtaining the curvature radius of the concave mirror and the inclination angle of the optical axis, and deriving the focal length of the concave mirror according to the curvature radius and the inclination angle of the optical axis;

[0019] S3, obtaining the offset height of the midpoint of the concave mirror relative to the plane where the bottom edge of the concave mirror is located, and deriving the current design distance from the midpoint of the concave mirror to the end surface of the first end according to the focal length, the offset height and the inclination angle of the optical axis;

[0020] S4, deriving the focal point position of the concave mirror according to the inclination angle of the optical axis, the current design distance and the offset height.

[0021] S5, setting the ferrule at the focal position; wherein the first end in the ferrule is directed towards the concave mirror, and the fluorescent light reflected by the concave mirror forms a light spot on the first end;

[0022] S6, obtaining the diameter of the light spot and determining whether the diameter of the light spot is equal to the diameter of the optical fiber;

[0023] S71, when the diameter of the light spot is equal to the diameter of the optical fiber, then the second end is directed towards the light source, and the third end is connected with the optical spectrum instrument, thereby completing the design of the optical fiber coupling monitoring device;

[0024] S72, when the diameter of the light spot is not equal to the diameter of the optical fiber, adjusting the current design distance according to a preset adjustment increment to obtain an adjusted current design distance, and returning to step S6.

[0025] Further, the step S2 specifically comprises the following steps:

[0026] The focal length f of the concave mirror is calculated by the formula ; wherein R is the radius of curvature of the concave mirror, is the optical axis inclination angle.

[0027] Further, the step S3 specifically comprises the following steps:

[0028] The current design distance of the midpoint of the concave mirror to the end surface of the first end is calculated by the formula ; wherein is the current design distance, is the offset height of the midpoint of the concave mirror relative to the plane where the bottom edge of the concave mirror is located.

[0029] Further, the step S72 specifically comprises the following steps:

[0030] If the diameter of the light spot is greater than the diameter of the optical fiber, then the current design distance is expanded according to a preset adjustment increment, so as to reduce the diameter of the light spot;

[0031] If the diameter of the light spot is less than the diameter of the optical fiber, then the current design distance is reduced according to a preset adjustment increment, so as to increase the diameter of the light spot.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] The application utilizes the characteristics that petroleum and other substances can reflect fluorescence under the irradiation of excitation light, the excitation light is transmitted through an optical fiber and then reflected by a concave mirror, and the excitation light is distributed on the surface of underground water, when underground water is polluted by petroleum, the pollutants are irradiated by the excitation light and then reflect fluorescence, the fluorescence is reflected and converged by the concave mirror and then coupled into the optical fiber, and then transmitted through the optical fiber to a spectrometer, the spectrometer receives the fluorescence and then decomposes it into different wave bands, and whether the specific fluorescent substance and its content are contained is judged from the characteristic spectrum line. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can also be obtained according to the structures shown in the drawings without any creative labor for those skilled in the art.

[0035] Figure 1 It is a connection diagram of the overall structure in an embodiment of the present application.

[0036] Figure 2 It is a cross-sectional view of a coupling assembly in an embodiment of the present application.

[0037] Figure 3 It is a fluorescence reflection diagram of a concave mirror and an optical fiber in an embodiment of the present application.

[0038] Figure 4 It is a flow diagram of a design method of an optical fiber coupling monitoring device in an embodiment of the present application.

[0039] The purposes, functional features and advantages of the present application will be further illustrated with reference to the embodiments and the accompanying drawings.

[0040] Explanation of the reference signs:

[0041] 1, concave mirror; 11, first edge line; 12, second edge line; 2, ferrule; 3, optical fiber; 31, first end; 32, second end; 33, third end; 4, light source; 5, spectrometer; 6, coupling assembly; 61, light inlet; 62, mounting groove; 63, ferrule hole. DETAILED DESCRIPTION

[0042] It should be understood that the specific embodiments described herein are merely intended to explain the present application, and are not intended to limit the present application.

[0043] With reference to the drawings and embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0044] It should be noted that all directional indications, such as up, down, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as described in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0045] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application.

[0046] Please refer to Figures 1 to 3 The embodiment provides an optical fiber coupling monitoring device, which comprises a light source 4, an optical fiber 3, a ferrule 2, a spectrometer 5 and a concave mirror 1, wherein:

[0047] The optical fiber 3 has a Y-shaped structure, the optical fiber 3 comprises a first end 31, a second end 32 and a third end 33, the first end 31 and the second end 32 are oppositely arranged on the two sides of the first end 31, the second end 32 and the third end 33 are both arranged away from the ferrule 2, and the first end 31 is fixedly connected with the ferrule 2;

[0048] The light source 4 is used for emitting excitation light, and the light source 4 is opposite to the end face of the second end 32;

[0049] The ferrule 2 has an inner hole extending along the extension direction of the ferrule 2, the first end 31 is fixed in the inner hole, and the end face of the first end 31 is exposed from the inner hole;

[0050] The spectrometer 5 is used for receiving fluorescent light reflected by the pollutants and analyzing the spectrum of the fluorescent light, and the third end 33 is connected with the spectrometer 5;

[0051] The mirror surface of the concave mirror 1 is arranged correspondingly to the end face of the first end 31.

[0052] The light source 4 of the embodiment emits excitation light, which enters the optical fiber 3 from the second end 32, is transmitted through the optical fiber 3 to the first end 31, and is emitted after being reflected by the concave mirror 1 to irradiate the underground water. When the underground water is contaminated by oil, the contaminants are irradiated by the excitation light and reflect fluorescent light. The fluorescent light is reflected and converged by the concave mirror 1, coupled into the first end 31 of the optical fiber 3, transmitted from the third end 33 of the optical fiber 3 to the spectrometer 5, and decomposed into different wave bands after being received by the spectrometer 5. The spectrometer 5 determines whether the fluorescent light contains specific fluorescent substances and the content thereof according to characteristic spectral lines.

[0053] The embodiment can monitor whether the underground water is contaminated by oil and gas in real time, and the complex sampling process in the water quality monitoring hole is avoided. Even a small range of oil and gas leakage can form a small oil film on the surface of the underground water to reflect fluorescent light, thereby significantly improving the progress of monitoring of the contaminants in the underground water. In the embodiment, the Y-shaped optical fiber can ensure that the fluorescent light received is transmitted to the spectrometer 5 during the continuous transmission of the excitation light, so that the emission of the excitation light and the reception of the fluorescent light are performed synchronously, thereby ensuring the real-time monitoring of the underground water. Moreover, the light collecting effect of the concave mirror 1 causes more fluorescent light to be collected on the optical fiber 3, thereby improving the response accuracy of the embodiment in response to a small range of oil and gas leakage. Since the concave mirror 1 is based on the reflection principle, the anti-pollution capability is stronger than that of a glass lens, and the waterproof problem does not need to be considered, thereby being more adaptable.

[0054] Specifically, the ferrule 2 is made of finished stainless steel material, and the coupling assembly 6 is made of aluminum material processed by CNC. The corrosion resistance of the aluminum material and the stainless steel material can better adapt to the harsh conditions of the underground water environment. In the embodiment, the concave mirror 1 is polished by a wool ball after being processed by the CNC process, so as to form a mirror surface and increase the reflectivity of the mirror surface from 50% to more than 90%. The wool ball polishing process not only significantly enhances the fluorescent signal intensity, but also can be polished again if the mirror surface is contaminated after a period of use, thereby being relatively simple to maintain.

[0055] In one embodiment, the end face of the first end 31 deviates from the plane in which the optical axis of the concave mirror 1 is located. Preferably, the excitation light emitted from the first end 31 is reflected by the concave mirror 1 in the form of parallel light, and then irradiates the underground water after being offset from the first end 31, thereby reducing the adverse effects of the direct reflection of the excitation light to the first end 31.

[0056] As a further preferred, the fluorescent light is reflected and converged by the concave mirror 1 to form a light spot, the diameter of the light spot is the same as the diameter of the end face of the first end 31, and the end face of the first end 31 is located at the position of the light spot, so that the fluorescent light is uniformly distributed on the end face of the first end 31, thereby improving the utilization rate of the optical fiber 3.

[0057] As further preferred in the embodiment, the fiber 3 in the prior art comprises a core, the first end 31 of the fiber 3 comprises a first branch and a second branch, the first branch is connected with the second end 32, and the second branch is connected with the third end 33. The ends of the cores in the first branch and the second branch are uniformly distributed on the end face of the first end 31, so that the fluorescence can be uniformly transmitted from the second branch to the spectrometer 5, and the excitation light from the second branch is uniformly distributed on the first end 31 of the fiber 3.

[0058] As shown in Figure 1 As further preferred, the concave mirror 1 comprises a first edge line 11 and a second edge line 12, the first edge line 11 and the second edge line 12 are located at both ends of the bending direction of the concave mirror 1, the first edge line 11 is away from the ferrule 2, and the second edge line 12 is close to the ferrule 2. The arc length of the cross section of the curved surface between the first edge line 11 and the second edge line 12 is less than 1 / 4 of the arc length of the circle on which the cross section is located.

[0059] As shown in Figure 2 In one embodiment, the coupling assembly 6 is further included, the coupling assembly 6 comprises a light collecting port 61, a mounting groove 62 and a ferrule hole 63, the mounting groove 62 and the ferrule hole 63 are located on both sides of the light collecting port 61, the mounting groove 62 and the ferrule hole 63 are opposite, the ferrule 2 is fixed in the ferrule hole 63, the end face of the first end 31 faces the concave mirror 1, the concave mirror 1 is fixed in the mounting groove 62, and the optical axis of the concave mirror 1 is inclined to the outside of the light collecting port 61. The light collecting port 61 faces the underground water surface, the fluorescence is emitted from the light collecting port 61, reflected by the concave mirror 1, and then gathered on the first end 31 of the fiber 3 in the ferrule 2. The coupling assembly 6 fixes the concave mirror 1 and the ferrule 2 together, so that the distance between the concave mirror 1 and the first end 31 is always consistent, and the convenience of underground installation of the embodiment is improved.

[0060] Further, the coupling assembly 6 further comprises a light-transmitting cover, which is wrapped outside the light collecting port, so as to avoid pollution of the concave mirror 1 and the fiber 3 by the underground water environment, thereby affecting the monitoring effect of the embodiment.

[0061] In the embodiment, the concave mirror 1 and the mounting groove 62 are further detachably connected in a buckle type. Specifically, the edge part of the mounting groove 62 connected with the first edge line 11 and the second edge line 12 of the concave mirror 1 is provided with a bayonet, and the first edge line 11 and the second edge line 12 are inserted into the bayonet to complete the fixation. When the concave mirror 1 is polluted or broken, the concave mirror 1 can be taken out from the mounting groove 62 for replacement.

[0062] As shown in Figure 3 and Figure 4As shown, the embodiment also provides a design method of a fiber coupling monitoring device, applied to the fiber coupling monitoring device as described above, comprising the following steps:

[0063] S1, an optical axis of the concave mirror 1 is obtained; wherein the optical axis is arranged obliquely relative to a horizontal plane;

[0064] S2, a curvature radius of the concave mirror 1 and an oblique angle of the optical axis are obtained, and a focal length of the concave mirror 1 is derived according to the curvature radius and the oblique angle of the optical axis;

[0065] The focal length f of the concave mirror 1 is calculated by using the formula ; wherein R is the curvature radius of the concave mirror 1, and is the oblique angle of the optical axis.

[0066] S3, an offset height of a midpoint of the concave mirror 1 relative to a plane where a second edge line of the concave mirror 1 is located is obtained, and a current design distance from the midpoint of the concave mirror 1 to an end face of the first end 31 is derived according to the focal length, the offset height and the oblique angle of the optical axis;

[0067] Specifically, the current design distance from the midpoint of the concave mirror 1 to the end face of the first end 31 is calculated by using the formula ; wherein f is the current design distance, is the offset height of the midpoint of the concave mirror 1.

[0068] S4, a focal point position of the concave mirror 1 is derived according to the oblique angle of the optical axis, the current design distance and the offset height;

[0069] S5, the insert core 2 is arranged at the focal point position; wherein the first end 31 located in the insert core 2 faces the concave mirror 1, and fluorescent light reflected by the concave mirror 1 forms a light spot on the first end 31;

[0070] S6, a diameter of the light spot is obtained, and it is judged whether the diameter of the light spot is equal to a fiber diameter;

[0071] S71, when the diameter of the light spot is equal to the fiber diameter, the second end 32 is arranged to face the light source 4, and the third end 33 is connected with the spectrometer 5, so as to complete the design of the fiber coupling monitoring device;

[0072] S72, when the diameter of the light spot is not equal to the fiber diameter, an adjusted current design distance is obtained by adjusting the current design distance according to a preset adjustment increment, and then the step S6 is returned.

[0073] The step S72 specifically comprises a step in the embodiment, and the preset adjustment increment is preferably 1 mm, 2 mm or 5 mm in the embodiment: ​

[0074] If the spot diameter is greater than the fiber diameter, then the current design distance is enlarged by a preset adjustment increment, so as to reduce the spot diameter.

[0075] If the spot diameter is less than the fiber diameter, then the current design distance is reduced by a preset adjustment increment, so as to increase the spot diameter.

[0076] In another aspect, it can be set whether the spot diameter is located in a preset range of the fiber diameter, and the preset range of the fiber diameter in the embodiment is preferably ±1mm.

[0077] If the spot diameter is greater than the preset range of the fiber diameter, then the current design distance is enlarged by a preset adjustment increment, so as to reduce the spot diameter.

[0078] If the spot diameter is less than the preset range of the fiber diameter, then the current design distance is reduced by a preset adjustment increment, so as to increase the spot diameter.

[0079] Further, the calculation formula of the spot diameter is as follows:

[0080]

[0081] Wherein, d is the spot diameter. The fiber diameter D in the embodiment is equal to the spot diameter d.

[0082] Preferably, in the embodiment, the first end 31 is positioned at the new focal point position of the inclined optical axis, and the coordinates satisfy the following formula:

[0083]

[0084] Wherein, x is the horizontal coordinate of the focal point in the sectional view, and y is the vertical coordinate of the focal point in the sectional view.

[0085] Through the design method of the fiber coupling monitoring device provided in the embodiment, the skilled person can quickly determine the optimal relative position of the first end 31 of the optical fiber 3 according to the existing concave mirror 1 and the installation angle, so as to facilitate the manufacture of the coupling assembly 6 to fix the relative distance between the concave mirror 1 and the ferrule 2, and facilitate the installation of the embodiment.

[0086] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent flow transformation obtained by using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for designing a fiber coupling monitoring device, applied to a fiber coupling monitoring device, the fiber coupling monitoring device comprising a light source, a fiber, a ferrule, a spectrometer and a concave mirror, wherein the fiber is Y-shaped, comprising a first end, a second end and a third end, the first end and the second end are oppositely arranged on both sides of the first end, the second end and the third end are both arranged away from the ferrule, and the first end is fixedly connected to the ferrule; the light source is used for emitting excitation light, and the light source is opposite to the end face of the second end; the ferrule has an inner hole extending along the extending direction of the ferrule, the first end is fixed in the inner hole, and the end face of the first end is exposed from the inner hole; the spectrometer is used for receiving fluorescent light reflected by contaminants and analyzing the spectrum of the fluorescent light, and the third end is connected to the spectrometer; the mirror surface of the concave mirror is arranged corresponding to the end face of the first end; the end face of the first end is offset from the plane where the optical axis of the concave mirror is located, so that the excitation light is not reflected back to the first end by the concave mirror after being emitted, and the first end receives the fluorescent light while emitting the excitation light; and the method comprises the following steps: S1, obtaining the optical axis of the concave mirror, wherein the optical axis is arranged to be inclined relative to the horizontal plane, so that the excitation light is irradiated to the groundwater surface; S2, obtaining the curvature radius of the concave mirror and the inclination angle of the optical axis, and obtaining the focal length of the concave mirror according to the curvature radius and the inclination angle of the optical axis; S3, obtaining the offset height of the midpoint of the concave mirror relative to the plane where the bottom edge of the concave mirror is located, and obtaining the current design distance from the midpoint of the concave mirror to the end face of the first end according to the focal length, the offset height and the inclination angle of the optical axis; S4, obtaining the focal point position of the concave mirror according to the inclination angle of the optical axis, the current design distance and the offset height; S5, arranging the ferrule at the focal point position, wherein the first end in the ferrule faces the concave mirror, and the fluorescent light reflected by the concave mirror forms a light spot on the first end, so that the fluorescent light is coupled into the first end by the concave mirror; S6, obtaining the diameter of the light spot, and determining whether the diameter of the light spot is equal to the diameter of the fiber; S71, when the diameter of the light spot is equal to the diameter of the fiber, then the second end is opposite to the light source, and the third end is connected to the spectrometer, thereby completing the design of the fiber coupling monitoring device; and S72, when the diameter of the light spot is not equal to the diameter of the fiber, adjusting the current design distance by a preset adjustment increment to obtain an adjusted current design distance, and returning to step S6. The fluorescent light is converged to form a light spot after being reflected by the concave mirror, the diameter of the light spot is the same as the diameter of the end face of the first end, and the end face of the first end is located at the position of the light spot. The first end of the fiber is provided with a first branch and a second branch, the first branch is connected to the second end, the second branch is connected to the third end, and the ends of the fiber cores in the first branch and the second branch are uniformly distributed on the end face of the first end. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The method of designing a fiber-coupled monitoring device according to claim 1, wherein, ​ 3. The method of designing a fiber-coupled monitoring device according to claim 1, wherein, ​ 4. The method of designing a fiber-coupled monitoring device according to claim 1, wherein, The concave mirror comprises a first edge line and a second edge line, the first edge line and the second edge line are located at two ends of a bending direction of the concave mirror, the first edge line is away from the plug core, the second edge line is close to the plug core, and an arc length of a cross-section circular arc between the first edge line and the second edge line is less than 1 / 4 arc length of a circle on which the cross-section circular arc is located.

5. The method of designing a fiber-coupled monitoring device according to claim 1, wherein, The coupling assembly comprises a light collecting port, a mounting groove and a plug core hole, the mounting groove and the plug core hole are located on two sides in the light collecting port, the mounting groove and the plug core hole are opposite, the plug core is fixed in the plug core hole, an end surface of the first end faces the concave mirror, the concave mirror is fixed in the mounting groove, and an optical axis of the concave mirror is inclined to outside of the light collecting port.

6. The method of designing a fiber-coupled monitoring device according to claim 1, wherein, The step S2 specifically comprises the steps of: The focal length f of the concave mirror is calculated by the formula where R is the radius of curvature of the concave mirror, is the inclination angle of the optical axis.

7. The method of designing a fiber-coupled monitoring device according to claim 6, wherein, The step S3 specifically comprises the steps of: The current design distance of the midpoint of the concave mirror to the end surface of the first end is calculated by using the formula ; wherein, is the current design distance, is the offset height of the midpoint of the concave mirror relative to the plane where the bottom edge of the concave mirror is located.

8. The method of designing a fiber-coupled monitoring device according to claim 6, wherein, The step S72 specifically comprises the steps of: If the spot diameter is greater than the fiber diameter, then the current design distance is enlarged by a preset adjustment increment, so that the spot diameter is reduced; If the spot diameter is less than the fiber diameter, then the current design distance is reduced by a preset adjustment increment, so that the spot diameter is increased.

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