A fiber optic tilt sensor

Abstract

The present invention discloses a fiber optic tilt sensor, comprising: a mounting tube having an upper-opening accommodating cavity; a tube cover removably mounted on the upper end of the accommodating cavity; a mounting base removably mounted on the tube cover, with a vertically extending wire hole extending through the center; an elastic metal sheet fixedly connected at its upper end to the bottom of the mounting base and having a counterweight attached to its bottom; the elastic metal sheet having a wire-passing notch with an upper opening aligned with the wire-passing hole; two slots at the bottom of the wire-passing notch, each with an insertion opening formed on either side of the elastic metal sheet; positioning slots provided on the circumferential walls at both ends of the slots; two optical fibers having an extension section and a Bragg grating section; the Bragg grating sections of the two optical fibers fixedly mounted in the two slots, respectively; and radial protrusions provided on the outer circumferential walls at both ends of the Bragg grating sections for inserting into the positioning slots. The present invention enables the Bragg grating sections to better follow the deformation of the elastic metal sheet, thereby improving the measurement accuracy and reliability of the sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of tilt angle measurement, in particular to an optical fiber tilt sensor. Background Art

[0002] Tilt sensing is a critical technology widely used in industries such as industry, construction, and transportation. It primarily measures the tilt angle or change in an object's tilt relative to the ground. With the advancement of modern technology, the demand for tilt sensing technology continues to grow, playing a vital role in scenarios such as structural health monitoring, equipment attitude control, and navigation. Early tilt measurement methods relied on bubble levels, which, while simple and reliable, were limited in sensitivity and accuracy.

[0003] Fiber-optic tilt sensors are attracting increasing attention due to their high sensitivity, resistance to electromagnetic interference, and adaptability to harsh environments. These sensors utilize refraction, reflection, or grating effects within optical fibers to detect tilt angle changes, making them suitable for long-distance monitoring and high-precision applications. Typically, a grating segment of the optical fiber is connected to a deformable component to enable measurement. However, a loose and unstable connection between the grating segment and the deformable component can result in the grating segment not properly following the deformation of the component, affecting measurement results. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an optical fiber tilt sensor.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A fiber optic tilt sensor comprises: a mounting tube having an accommodating cavity with an upper opening; a tube cover, a detachable cover arranged at the upper end of the accommodating cavity; a mounting base, detachably mounted on the tube cover, and having a wire passing hole vertically passing through the center; an elastic metal sheet, the upper end of which is fixedly connected to the bottom of the mounting base, the bottom of which is connected to a counterweight block, the elastic metal sheet being provided with a wire passing notch with an upper opening and aligned with the wire passing hole; two slots being provided at the bottom of the wire passing notch, the two slots respectively forming embedding openings on the two side surfaces of the elastic metal sheet; positioning slots being provided on the circumferential walls at both ends of the slots; two optical fibers having an extension section and a Bragg grating section, the extension sections both passing through the wire passing hole and the wire passing notch; the Bragg grating sections of the two optical fibers being fixedly mounted on the two slots respectively, and the outer circumferential walls at both ends of the Bragg grating sections being provided with radial protrusions embedded in the positioning slots.

[0007] Furthermore, the counterweight block is hinged to the bottom of the elastic metal sheet, and the hinge axis of the counterweight block is perpendicular to the thickness direction of the elastic metal sheet.

[0008] Furthermore, the bottom of the cylinder cover is provided with a raised limit block, and the limit block is provided with a limit hole; the accommodating cavity peripheral wall is provided with a mounting block, and the mounting block is provided with a through hole, and a movable column is movably passed through the through hole, and one end of the movable column is provided with a plug, and the other end is detachably connected to a dial ring, and the inner end of the plug is provided with a resisting ring, and a spring is sleeved on the movable column; one end of the spring abuts against the resisting ring, and the other end abuts against the mounting block; the movable column has a limited state and a disassembly state; in the limited state, the dial ring abuts against the mounting block, and the plug is inserted into the limiting hole; the plug in the disassembly state disengages from the limiting hole; the outer circumference of the mounting cylinder is rotatably sleeved with a movable cylinder, and the movable cylinder is provided with a dial rod that passes through the cylinder wall of the mounting cylinder and is inserted into the accommodating cavity, and the rotation of the movable cylinder can drive the dial rod to move the dial ring, thereby making the movable column move from the limited state to the disassembly state.

[0009] Furthermore, the upper end of the shift ring protrudes from the mounting block, the shift rod contacts the upper end of the shift ring, and the shift rod is higher than the mounting block.

[0010] Furthermore, the wall of the mounting tube is provided with a movable notch with an upper opening, and the shifting rod is passed through the movable notch.

[0011] Furthermore, the movable notch has two end walls, and when the shifting rod abuts against the two end walls respectively, the movable column is in a limited state and a disassembled state respectively.

[0012] Furthermore, the mounting seat includes a top plate and a plug post, the plug post is connected to the bottom of the top plate, a socket for inserting the plug post is provided in the center of the cylinder cover, a clamping block is provided on the peripheral wall of the bottom of the plug post, a through groove for the clamping block to pass through is provided on the peripheral wall of the socket, the clamping block can rotate to be staggered with the through groove after passing through the through groove, a sinking groove is provided at the upper end of the socket for the top plate to be embedded, an elastic clamping column with elastic lifting and lowering movement is installed on the bottom wall of the sinking groove, and a positioning hole is provided on the bottom surface of the top plate; when the elastic clamping column is inserted into the positioning hole, the clamping block is staggered with the through groove, the bottom surface of the top plate is in contact with the bottom wall of the sinking groove, and the clamping block is in contact with the bottom surface of the cylinder cover.

[0013] Furthermore, a positioning block is provided on the bottom surface of the cylinder cover. When the clamping block abuts against the positioning block, the clamping block is staggered with the through groove, and the elastic clamping column is aligned with the positioning hole; an unlocking hole extending to the top surface of the top plate is provided on the top of the positioning hole.

[0014] Furthermore, it also includes a fixing piece connected to the elastic metal sheet, which is used to limit the Bragg grating segment in the slot.

[0015] Furthermore, the fixing member is a connecting plate, and an embedded portion is provided at both ends of the connecting plate. The radial protrusions are provided in two groups and the two groups of radial protrusions are respectively provided at both ends of the Bragg grating segment. The two radial protrusions in the same group are formed with annular grooves, and the embedded portion is embedded in the corresponding annular grooves.

[0016] The present invention has the following beneficial effects:

[0017] By fixing the optical fiber's Bragg grating segment in the slot of the elastic metal sheet and utilizing the coordination of radial protrusions and positioning grooves, a tight connection between the optical fiber Bragg grating segment and the elastic metal sheet is ensured. This allows the Bragg grating segment to stably follow the deformation of the elastic metal sheet, thereby accurately reflecting changes in the tilt angle. This avoids measurement errors caused by the loose connection between the grating segment and the deforming parts in traditional optical fiber tilt sensors, significantly improving the sensor's measurement accuracy and stability. The use of a detachable mounting tube, tube cover, and mounting base design makes the installation and replacement of the optical fiber more convenient. When tilting occurs, the counterweight causes the elastic metal sheet to deform, causing the Bragg grating segment on one side to be stretched and the Bragg grating segment on the other side to be compressed, enabling accurate sensing of the deformation caused by the tilt. The detachable connection between the tube cover and the mounting base facilitates the installation and maintenance of the optical fiber, further improving the practicality and cost-effectiveness of the sensor.

[0018] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 1 is a schematic diagram of the overall structure of an embodiment of the present invention;

[0021] Figure 2 is an internal cross-sectional view of an embodiment of the present invention;

[0022] Figure 3 yes Figure 1 Schematic diagram of the decomposed state structure;

[0023] Figure 4 It is a schematic diagram of the local structure in the limit state;

[0024] Figure 5 It is a schematic diagram of the local structure in the disassembled state;

[0025] Figure 6 It is a schematic diagram of the local structural decomposition at the movable column;

[0026] Figure 7 It is a schematic diagram of the connection structure of the cylinder cover, the mounting seat and the elastic metal sheet;

[0027] Figure 8 yes Figure 7A magnified view of point A;

[0028] Figure 9 It is a schematic diagram of the decomposed state structure at the Bragg grating segment;

[0029] Figure 10 yes Figure 7 A partial view of the exploded state;

[0030] Figure 11 It is a schematic diagram of the exploded structure of the mounting base and the cylinder cover;

[0031] Figure 12 It is a partial cross-sectional view of the elastic clamping column;

[0032] Figure 13 This is a schematic diagram of the connection between the optical fiber tilt sensor of the present invention, the optical fiber splitter, the broadband light source, and the spectrum analyzer;

[0033] Figure 14 is a spectrum diagram of the detection output of an embodiment of the present invention;

[0034] Figure 15 This is a fitting diagram of the central wavelength difference and the tilt angle.

[0035] Legend:

[0036] The mounting cylinder 100, the accommodating cavity 110, the mounting block 120, the through hole 121, the movable column 130, the plug 131, the shift ring 132, the retaining ring 133, the spring 134, the movable notch 140, and the end wall 141;

[0037] Cylinder cover 200, limiting block 210, limiting hole 211, insertion hole 220, through slot 221, sinking slot 230, mounting slot 231, elastic clamping column 240, positioning block 250, positioning protrusion 260;

[0038] Mounting seat 300, wire hole 301, top plate 310, positioning hole 311, unlocking hole 312, plug post 320, and block 321;

[0039] Elastic metal sheet 400, counterweight block 410, wire notch 420, slot 421, positioning slot 422;

[0040] Optical fiber 500, extension section 510, Bragg grating section 520, radial protrusion 521, annular groove 522;

[0041] Connecting plate 600, embedded portion 610;

[0042] Movable cylinder 700, lever 710;

[0043] Fiber optic splitter 800 , broadband light source 801 , and optical spectrum analyzer 802 . DETAILED DESCRIPTION

[0044] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0047] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0048] Please refer to Figure 1 and Figure 2 A fiber optic tilt sensor in a preferred embodiment of the present invention includes a mounting tube 100, a tube cover 200, a mounting seat 300, an elastic metal sheet 400, and an optical fiber 500.

[0049] The mounting tube 100 has an upper opening accommodating chamber 110. The tube cover 200 is detachably mounted on the upper end of the accommodating chamber 110, thereby forming a sealed space to protect the elastic metal sheet 400 and the optical fiber 500.

[0050] The mounting base 300 can be detachably mounted on the cylinder cover 200, and a wire hole 301 is provided in the center of the mounting base 300, which passes vertically through it. The upper end of the elastic metal sheet 400 is fixedly connected to the bottom of the mounting base 300. Specifically, the upper end of the elastic metal sheet 400 can be connected to the mounting base 300 through fasteners, or the upper end of the elastic metal sheet 400 can be inserted into the mounting base 300 and connected through fasteners. Of course, the elastic metal sheet 400 and the mounting base 300 can also be integrally formed. A counterweight block 410 is connected to the bottom of the elastic metal sheet 400, and the elastic metal sheet 400 is provided with a wire notch 420 with an upper opening aligned with the wire hole 301, so that the wire harness can extend out. Refer to Figure 9 Two slots 421 are provided at the bottom of the wire-passing notch 420. Each slot 421 has an insertion opening formed on either side of the elastic metal sheet 400. Specifically, the two slots 421 are spaced apart along the thickness direction of the elastic metal sheet 400. The upper ends of the slots 421 communicate with the wire-passing notch 420. The slots 421 have an insertion opening formed on the side of the elastic metal sheet 400 that is closest to the wire-passing notch 420, facilitating insertion from the insertion opening during installation. For example, if the thickness direction of the elastic metal sheet 400 is left-right, the two slots 421 are spaced apart left-right. The left slot 421 forms an insertion opening on the left side of the elastic metal sheet 400, and the right slot 421 forms an insertion opening on the right side of the elastic metal sheet 400. Positioning grooves 422 are provided on the surrounding walls at both ends of the slots 421.

[0051] Two optical fibers 500 are provided, each having an extension section 510 and a Bragg grating section 520. The extension section 510 is passed through the wire hole 301 and the wire notch 420. The Bragg grating sections 520 of the two optical fibers 500 are fixedly mounted in two slots 421, respectively. The Bragg grating sections 520 can be secured to the slots 421 using additional connectors or by filling the slots 421 with glue, such as casting glue or welding glue. Alternatively, the Bragg grating sections 520 can be coated with a metal layer, which is then welded to the elastic metal sheet 400 to secure the Bragg grating sections 520. The outer walls of the two ends of the Bragg grating sections 520 are provided with radial protrusions 521 that engage with the positioning grooves 422.

[0052] The present invention provides a fiber optic tilt sensor. By fixing the Bragg grating segment 520 of an optical fiber 500 in a slot 421 of an elastic metal sheet 400, and utilizing the cooperation of a radial protrusion 521 and a positioning groove 422, the fiber optic Bragg grating segment 520 is ensured to be tightly connected to the elastic metal sheet 400. This allows the Bragg grating segment 520 to stably follow the deformation of the elastic metal sheet, thereby accurately reflecting changes in the tilt angle. This avoids measurement errors caused by the loose connection between the grating segment and the deforming part in traditional fiber optic tilt sensors, significantly improving the sensor's measurement accuracy and stability. The use of a detachable mounting tube, tube cover, and mounting base design facilitates the installation and replacement of the optical fiber. When tilting occurs, the counterweight 410 causes the elastic metal sheet 400 to deform, causing the Bragg grating segment 520 on one side to be tensile and the Bragg grating segment 520 on the other side to be compressive, enabling accurate sensing of the deformation caused by tilt. Furthermore, the detachable connection between the tube cover 200 and the mounting base 300 facilitates installation and maintenance of the optical fiber 500, further improving the practicality and cost-effectiveness of the sensor.

[0053] Reference Figure 2 In some embodiments of the present invention, the counterweight 410 is hinged to the bottom of the elastic metal sheet 400, and the hinge axis of the counterweight 410 is perpendicular to the thickness direction of the elastic metal sheet 400. This makes the counterweight 410 and the bottom of the elastic metal sheet 400 movably connected, allowing the counterweight 410 to change its posture according to the tilt angle, and avoiding the stress concentration at the connection caused by the rigid connection between the counterweight 410 and the bottom of the elastic metal sheet 400.

[0054] Reference Figure 3 、 Figure 4 、 Figure 5 and Figure 6 In a further embodiment of the present invention, a raised stopper 210 is provided on the bottom of the barrel cover 200, with a stopper hole 211 defined therein. A mounting block 120 is provided on the peripheral wall of the accommodating chamber 110, with a through-hole 121 defined therein. A movable post 130 is movably inserted through the through-hole 121. The through-hole 121 is adapted to the cross-section of the movable post 130 to provide a movable guide and positioning function. The movable post 130 has a plug 131 at one end and a removable pull ring 132 at the other end. Specifically, a stud is provided at the other end of the movable post 130, and a threaded hole is defined in the center of the pull ring 132 for threaded connection to the stud, thereby facilitating installation and removal. A retaining ring 133 is provided at the inner end of the plug 131, and a spring 134 is sleeved on the movable column 130; one end of the spring 134 abuts against the retaining ring 133, and the other end abuts against the mounting block 120, thereby applying elastic force to the plug 131 so that when it is aligned with the limiting hole 211, it can automatically insert into the limiting hole 211 to achieve vertical limiting of the cylinder cover 200; the movable column 130 has a limiting state and a disassembled state. Figure 2 and Figure 4As shown, in the limited state, the dial ring 132 is against the mounting block 120, and the plug 131 is inserted into the limited hole 211. In order to facilitate the insertion, the end of the plug 131 is provided with a chamfer, and at this time the cylinder cover 200 is in contact with the upper end surface of the mounting cylinder 100 to seal the upper end of the accommodating cavity 110. Figure 5 As shown, the plug 131 in the disassembled state is disengaged from the limiting hole 211, and the limiting block 210 is now released, allowing the cylinder cover 200 to be directly pulled upward and removed, thereby achieving the disassembly of the cylinder cover 200 from the installation cylinder 100. The installation cylinder 100 is provided with a movable cylinder 700 that is rotatably sleeved on its outer periphery. The movable cylinder 700 is provided with a lever 710 that passes through the cylinder wall of the installation cylinder 100 and is inserted into the accommodating cavity 110. The rotation of the movable cylinder 700 can drive the lever 710 to move the dial ring 132, thereby moving the movable column 130 from the limited state to the disassembled state. When there is no external force, the plug 131, if aligned with the limiting hole 211, can automatically return to the limited state under the action of the spring 134. The spring 134 can specifically be a compression spring.

[0055] Therefore, the state of the movable column 130 can be switched by rotating the movable cylinder 700 outside the accommodating cavity 110, thereby achieving installation and removal of the cylinder cover 200, which is simple and convenient to operate.

[0056] Reference Figure 4 、 Figure 5 and Figure 6 In a further embodiment of the present invention, the upper end of the dial ring 132 protrudes from the mounting block 120, and the lever 710 contacts the upper end of the dial ring 132. The lever 710 is higher than the mounting block 120. This allows the lever 710 to rotate around the mounting block 120 to move the dial ring 132, thus avoiding structural interference. Furthermore, the lever 710 being higher than the mounting block 120 also eliminates the need for the lever 710 to pass over the mounting block 120 and the movable column 130 during installation, thus avoiding structural interference during installation.

[0057] Reference Figure 4 、 Figure 5 and Figure 6In a further embodiment of the present invention, the wall of the mounting tube 100 is provided with a movable notch 140 with an upper opening, and the shifting rod 710 is passed through the movable notch 140 and can rotate and swing in the movable notch 140 to drive the shifting ring 132 and the movable column 130 to move. During installation, first install the movable column 130 on the mounting block 120, and then install the movable cylinder 700. The lever 710 is inserted into the movable notch 140 from the upper end of the movable notch 140, and then the movable cylinder 700 is rotated so that the lever 710 moves the dial ring 132 and the movable column 130 to the disassembly state. Then the cylinder cover 200 is installed. After the cylinder cover 200 is in place, the movable cylinder 700 is released. Under the action of the spring 134, the plug 131 of the movable column 130 is inserted into the limiting hole 211, and the installation is completed. For disassembly, the movable cylinder 700 is rotated so that the lever 710 moves the dial ring 132 and the movable column 130 to the disassembly state. After the plug 131 is out of the limiting hole 211, the cylinder cover 200 can be directly removed upwards. It can be understood that in order for the cylinder cover 200 to be installed in the specified position during installation so that the plug 131 is aligned with the limiting hole 211, there is no need to repeatedly rotate and adjust the position of the cylinder cover 200. Refer to Figure 7 A positioning protrusion 260 is provided on the surface of the cylinder cover 200 that fits in with the upper end surface of the installation cylinder 100. The positioning protrusion 260 is embedded in the upper end of the movable notch 140 to achieve circumferential positioning. Therefore, during installation, it is only necessary to embed the positioning protrusion 260 into the movable notch 140 to ensure that the limiting hole 211 can be accurately aligned with the plug 131.

[0058] Reference Figure 4 、 Figure 5 In a further embodiment of the present invention, the movable notch 140 has two end walls 141. When the lever 710 respectively abuts against the two end walls 141, the movable column 130 is respectively in a limited state and a disassembled state. That is, when the lever 710 needs to switch the state of the movable column 130, it only needs to be rotated until it abuts against the other end wall 141 to indicate that the switching is completed, which is convenient for judgment during operation.

[0059] Reference Figure 8 、 Figure 10 、 Figure 11 and Figure 12When the jack is in the jacking position, the jack 320 is in the jacking position, and the jack 321 is in the jacking position, and the jack 321 is in the jacking position, and the jack 321 is in the jacking position, and the jack 321 is in the jacking position. The bottom surface of the top plate 310 fits against the bottom wall of the sink 230, and the clamping block 321 fits against the bottom surface of the cylinder cover 200, achieving vertical positioning of the mounting base 300. The elastic clamping column 240 then engages the positioning hole 311 to achieve circumferential positioning of the mounting base 300, ensuring that the clamping block 321 and the through-slot 221 are staggered, thereby achieving stable positioning and installation of the mounting base 300. No fasteners are required for installation and fixation, facilitating subsequent disassembly and maintenance. To facilitate disassembly, the cross-sectional profile of the elastic metal sheet 400 and the counterweight 410 is smaller than the insertion hole 220, allowing them to pass directly through the insertion hole 220 and be removed as a whole along with the mounting base 300.

[0060] Reference Figure 8 、 Figure 10 、 Figure 11 and Figure 12In a further embodiment of the present invention, a positioning block 250 is provided on the bottom surface of the cylinder cover 200. When the block 321 abuts the positioning block 250, the block 321 is offset from the through-slot 221, and the elastic clamping column 240 is aligned with the positioning hole 311, thereby facilitating alignment of the elastic clamping column 240 with the positioning hole 311. The top of the positioning hole 311 is provided with an unlocking hole 312 extending to the top surface of the top plate 310. During installation, the block 321 is aligned with the through-slot 221 and inserted until the bottom surface of the top plate 310 is aligned with the bottom wall of the sink 230. At this point, the upper end surface of the block 321 is flush with the bottom surface of the cylinder cover 200. The mounting base 300 is then rotated until the block 321 abuts the positioning block 250. At this point, the elastic clamping column 240 is aligned with the positioning hole 311 and, under the action of the elastic force, the elastic clamping column 240 is engaged in the positioning hole 311, achieving circumferential positioning of the mounting base 300. When unlocking is required, the cylinder cover 200 does not need to be removed. Instead, a pin can be inserted through the unlocking hole 312 to push the elastic clamping column 240 out of the positioning hole 311. The mounting base 300 can then be rotated until the block 321 is aligned with the through-slot 221. The mounting base 300 can then be pulled upward and removed, thereby facilitating installation. It is understood that to ensure stable installation of the elastic clamping column 240, a guide post is provided at the bottom of the elastic clamping column 240, a mounting groove 231 is provided on the bottom wall of the sink 230, and a guide hole is provided on the bottom wall of the mounting groove 231. A nut is inserted through the guide hole and connected to the bottom of the guide post. A compression spring is sleeved on the guide post to achieve elastic and movable installation of the elastic clamping column 240.

[0061] Reference Figures 7 to 9 In some embodiments of the present invention, a fixing member is further included, which is connected to the elastic metal sheet 400 and is used to limit the Bragg grating segment 520 in the slot 421, thereby limiting and fixing the Bragg grating segment 520. When it is necessary to fill glue in the slot 421, it can ensure that the position of the Bragg grating segment 520 is stable during the filling process.

[0062] In a specific embodiment of the present invention, the fixing member is a connecting plate 600. The connecting plate 600 is attached to the elastic metal sheet 400 and has corresponding holes for fastening and fixing via fasteners. Embedding portions 610 are provided at both ends of the connecting plate 600. Two sets of radial protrusions 521 are provided, one at each end of the Bragg grating segment 520. The two radial protrusions 521 in the same set are formed with an annular groove 522, and the embedding portions 610 are embedded in the corresponding annular groove 522. The embedding portions 610 are specifically arc-shaped plates. The semi-circular plate is embedded in the annular groove 522 formed between the two radial protrusions 521, thereby positioning and fixing the two ends of the Bragg grating segment 520.

[0063] Its working principle is: refer to Figure 13One side of the fiber optic splitter 800 is connected to two optical fibers 500, while the other side has two interfaces connected to a broadband light source 801 and a spectrum analyzer 802, respectively. Light emitted by the light source passes through a 2×2 splitter and enters the two optical fibers 500. The light passing through the two Bragg grating segments 520 is reflected back to the spectrometer for reception and demodulation. The optical fibers are SMF-28 standard single-mode fibers, with center wavelengths of 1545.6 nm and 1550.3 nm, respectively. The surface coating of the fiber grating is removed and replaced with a copper coating with a thickness of 25 μm. The two copper-coated Bragg grating segments 520 are fixed to two symmetrical surfaces of the elastic metal sheet 400. The tilt sensitivity of the sensor can be adjusted by varying the length and thickness of the elastic metal sheet 400 and the weight of the mass block.

[0064] When the sensor is tilted, the two Bragg grating segments 520 are subjected to tension or compression, respectively, causing a redshift or blueshift in the spectrum. The tilt angle can be determined based on the spectral shift of the two Bragg grating segments 520. When the sensor tilt angle changes, the bending stress of the mass block on the two FBGs (Bragg grating segments 520) changes, causing the spectral shift to change. Therefore, the sensor tilt angle can be determined based on the FBG center wavelength shift.

[0065] In one embodiment, when performing tilt detection, the output spectrum is as follows: Figure 14 The fitting straight line of the difference between the center wavelengths of the two Bragg grating segments 520 and the tilt angle is shown as Figure 15 As shown, since the temperature sensitivity of the two FBGs (Bragg grating segments 520) is the same, when the temperature changes, the difference in the center wavelengths of the two FBGs is not affected by the temperature, so the optical fiber tilt sensor is insensitive to temperature.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A fiber optic tilt sensor, characterized in that: include: A mounting cylinder having a receiving cavity with an upper opening; A cylinder cover, a detachable cover is provided at the upper end of the accommodating chamber; The mounting base can be detachably mounted on the cylinder cover, and a vertical wire hole is provided in the center; An elastic metal sheet, the upper end of which is fixedly connected to the bottom of the mounting base, and a counterweight block is connected to the bottom. The elastic metal sheet is provided with a wire-passing notch with an upper opening aligned with the wire-passing hole, and two slots are provided at the bottom of the wire-passing notch. The two slots respectively form an embedding opening on the two sides of the elastic metal sheet; positioning grooves are provided on the peripheral walls at both ends of the slots; Two optical fibers, each having an extension section and a Bragg grating section, wherein the extension section is passed through the wire hole and the wire notch; the Bragg grating sections of the two optical fibers are fixedly mounted in the two slots, respectively, and the outer peripheral walls at both ends of the Bragg grating section are provided with radial protrusions embedded in the positioning grooves; The bottom of the cylinder cover is provided with a raised limit block, and the limit block is provided with a limit hole; the peripheral wall of the accommodating cavity is provided with a mounting block, and the mounting block is provided with a through hole, and a movable column is movably passed through the through hole, and a plug is provided at one end of the movable column, and a dial ring is detachably connected to the other end, and a retaining ring is provided at the inner end of the plug, and a spring is sleeved on the movable column; one end of the spring is against the retaining ring, and the other end is against the mounting block; the movable column has a limited state and a disassembled state; in the limited state, the dial ring is against the mounting block, and the plug is inserted into the limited hole; the plug in the disassembled state is separated from the limited hole; the outer periphery of the mounting cylinder The rotating movable sleeve is provided with a movable cylinder, and the movable cylinder is provided with a shift rod which passes through the cylinder wall of the mounting cylinder and is inserted into the accommodating cavity. The rotating movement of the movable cylinder can drive the shift rod to shift the shift ring, thereby making the movable column move from the limited state to the disassembly state; the cylinder wall of the mounting cylinder is provided with a movable notch with an upper opening, and the shift rod is passed through the movable notch; the movable notch has two end walls, and when the shift rod is respectively against the two end walls, the movable column is respectively in the limited state and the disassembly state; a positioning protrusion is provided on the surface of the cylinder cover that fits with the upper end surface of the mounting cylinder, and the positioning protrusion is embedded in the upper end of the movable notch.

2. The optical fiber tilt sensor according to claim 1, characterized in that: The counterweight block is hinged to the bottom of the elastic metal sheet, and the hinge axis of the counterweight block is perpendicular to the thickness direction of the elastic metal sheet.

3. The optical fiber tilt sensor according to claim 1, wherein the upper end of the shift ring protrudes from the mounting block, the shift rod contacts the upper end of the shift ring, and the shift rod is higher than the mounting block.

4. The optical fiber tilt sensor according to claim 1, characterized in that: The mounting seat includes a top plate and a plug post, the plug post is connected to the bottom of the top plate, the center of the cylinder cover is provided with a socket for the plug post to be inserted, the bottom peripheral wall of the plug post is provided with a clamping block, the peripheral wall of the plug post is provided with a through groove for the clamping block to pass through, the clamping block can rotate to be staggered with the through groove after passing through the through groove, the upper end of the plug post is provided with a sinking groove for the top plate to be embedded, the bottom wall of the sinking groove is installed with an elastic clamping column with elastic lifting and lowering movement, and the bottom surface of the top plate is provided with a positioning hole; when the elastic clamping column is inserted into the positioning hole, the clamping block is staggered with the through groove, the bottom surface of the top plate is in contact with the bottom wall of the sinking groove, and the clamping block is in contact with the bottom surface of the cylinder cover.

5. The optical fiber tilt sensor according to claim 4, characterized in that: A positioning block is provided on the bottom surface of the cylinder cover. When the clamping block abuts against the positioning block, the clamping block and the through groove are staggered, and the elastic clamping column is aligned with the positioning hole; an unlocking hole extending to the top surface of the top plate is provided on the top of the positioning hole.

6. The optical fiber tilt sensor according to claim 1, characterized in that: It also includes a fixing piece connected to the elastic metal sheet and used for limiting the Bragg grating segment in the slot.

7. The optical fiber tilt sensor according to claim 6, characterized in that: The fixing member is a connecting plate, and an embedded portion is provided at both ends of the connecting plate. The radial protrusions are provided in two groups, and the two groups of radial protrusions are respectively provided at both ends of the Bragg grating segment. The two radial protrusions in the same group are formed with an annular groove, and the embedded portion is embedded in the corresponding annular groove.

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