Optical fiber polishing method and polishing device

Abstract

The present invention relates to the technical field of optical fiber sensors, and proposes an optical fiber grinding method and a grinding processing device, wherein an optical fiber FP sensor is clamped by a designed optical fiber clamping mechanism, and is driven to move through a three-axis displacement mechanism and a grinding disc to perform optical fiber grinding. A host computer electrically controls the three-axis displacement mechanism and the grinding disc, and during the grinding process, a demodulation system is composed of a broadband light source, an optical circulator, and a spectrometer to detect optical fiber spectrum information and convert it into an electrical signal, which is transmitted to the host computer. The host computer monitors the grinding thickness in real time through a demodulation algorithm, and establishes communication with the three-axis displacement mechanism and the grinding disc through a hardware module, and then controls the action of the three-axis displacement mechanism and the grinding disc according to the grinding thickness detection information. This method uses a demodulation algorithm and a spectral signal detection technology to realize online monitoring of cavity length thickness during the grinding process, which is conducive to ensuring processing accuracy and efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensors, and in particular to an optical fiber polishing method and a polishing processing device. Background Art

[0002] There are many different manufacturing methods to thin the diaphragm of the FP sensor to improve the pressure sensitivity of the sensor. The main processing methods currently include femtosecond laser processing, chemical etching and grinding. Among them, femtosecond laser processing will cause certain damage to the optical fiber itself, and the sensor is easily damaged during the shock wave measurement process. In addition, femtosecond laser processing equipment is relatively expensive, which makes the production cost of the sensor high. In the chemical etching method, since the corrosion rate of the fiber core is faster than that of the cladding, a hole will be left in the center of the diaphragm during the chemical etching process. The hole in the center will cause the diaphragm to be perforated when it is too thin, making it difficult to corrode the thickness of the diaphragm to a relatively small range. The presence of the hole will also reduce the surface quality of the FP sensor diaphragm, affecting the performance of the sensor, which is very unfavorable to the improvement of the sensitivity of the sensor.

[0003] The method of grinding the FP sensor diaphragm with a grinder can overcome the shortcomings of femtosecond laser processing that causes damage to the optical fiber and high production cost, and can also overcome the disadvantage of chemical etching that causes uneven corrosion and reduces the surface quality of the diaphragm.

[0004] The invention patent with the existing authorization announcement number CN113334198B discloses an optical fiber end face grinding system based on umbrella-shaped structure clamping, including a grinding device and a clamping device.

[0005] As in the above technical solution, during the grinding process, the optical fiber will move along the radial direction of the sandpaper driven by the connecting rod. However, the optical fiber is processed by grinding, and the precision itself is low. After the above grinding action, the shaking caused by the displacement and the uncontrollable swing of the connecting rod will further increase the difficulty of controlling the grinding precision of the optical fiber, thereby affecting the processing precision of the optical fiber.

[0006] In addition, its technical solution is to grind multiple optical fibers at the same time. However, when processing the length and thickness of the optical fiber cavity, it is difficult to ensure that all optical fibers meet the grinding requirements at the same time due to factors such as fiber clamping and deformation, which further increases the difficulty of grinding. Summary of the invention

[0007] In view of this, the present invention proposes an optical fiber polishing method and a polishing processing device that can effectively ensure the optical fiber polishing accuracy and facilitate processing, so as to solve the problem that the existing optical fiber polishing device has low polishing accuracy and it is difficult to ensure that all optical fibers reach the polishing accuracy at the same time.

[0008] The technical solution of the present invention is achieved in this way:

[0009] In one aspect, the present invention provides a method for polishing an optical fiber, comprising the following steps:

[0010] S11, setting a three-axis displacement mechanism and a grinding disc for optical fiber grinding, and using a host computer to electrically control the three-axis displacement mechanism and the grinding disc,

[0011] S12, setting a clamping assembly on the three-axis displacement mechanism, installing an optical fiber sensor on the clamping assembly, and the three-axis displacement mechanism drives the optical fiber sensor to move closer to or away from the grinding disc,

[0012] S13, when the optical fiber sensor is close to the grinding disc, determining the initial grinding point, and grinding the end of the optical fiber sensor by the grinding disc;

[0013] Among them, during the grinding process, a demodulation system composed of a broadband light source, an optical circulator and a spectrometer is used to detect the optical fiber spectral information and convert it into an electrical signal, which is transmitted to the host computer. The host computer monitors the grinding thickness in real time through the demodulation algorithm, and establishes communication with the three-axis displacement mechanism and the grinding disk through the hardware module, and then controls the movement of the three-axis displacement mechanism and the grinding disk according to the grinding thickness detection information.

[0014] On the basis of the above technical solution, preferably, the grinding thickness is calculated by the number of peaks, and the steps are as follows:

[0015] The optical fiber sensor is set up, and the sensor diaphragm is regarded as a solid cavity. The three reflection surfaces form two FP cavities. The incident light is reflected and transmitted to different degrees between the three reflection surfaces. Finally, the reflected light is superimposed and interfered with each other to form a spectrum. The three reflection surfaces are recorded as M1, M2 and M3 respectively. The intensity of the reflected light formed after the interference is expressed as:

[0016]

[0017] Where: is the output light intensity; , , are the reflectivities at the reflection surfaces M1, M2 and M3 respectively; is the output wavelength; , is the refractive index of the medium of the FP solid cavity and the FP hollow cavity; , are the cavity lengths of the FP solid cavity and the FP hollow cavity, respectively; is the ratio of pi; is the cosine function;

[0018] The interference signal of the FP solid cavity is:

[0019]

[0020] In the formula, , are the reflectivities at the reflection surfaces M1 and M2 respectively; is the refractive index of the medium of the FP solid cavity; is the cavity length of the FP solid cavity; is the ratio of pi; is the cosine function; is the output wavelength;

[0021] Considering the half-wave loss, the initial phase is , when the phase difference When the interference is destructive, the expression for the reduction of the cavity length of the FP solid cavity during the grinding process is:

[0022]

[0023] In the formula, is the interference order, i.e., the actual number of envelopes generated by the FP sensor during the grinding process; is the refractive index of the medium of the FP solid cavity, ; is the output wavelength; is the reduction in cavity length of the FP solid cavity; is the ratio of pi;

[0024] The grinding thickness is monitored in real time by the reduction of cavity length.

[0025] On the basis of the above technical solution, preferably, the initial grinding point is determined by the change in the length of the FP hollow cavity after being pressurized, and the steps are as follows:

[0026] According to the definition of Young's modulus:

[0027]

[0028] Where, E is Young's modulus; F is the applied pressure; S is the area of ​​the effective force-bearing cross section; L is the length of the FP hollow cavity; is the change in the length of the FP hollow core cavity; this equation can be transformed into:

[0029]

[0030] Where, E is Young's modulus; F is the applied pressure; S is the area of ​​the effective force-bearing cross section; L is the length of the FP hollow cavity; is the change in the length of the FP hollow core cavity;

[0031] When the pressure on the grinding disc changes, the length of the hollow core cavity of the optical fiber sensor FP will also change. When the structural parameters of the optical fiber sensor are determined, E, S, and L in the formula are determined values, and the change in the length of the hollow core cavity of the FP is proportional to the pressure on the optical fiber.

[0032] According to the above formula

[0033] ,

[0034] When the sensor diaphragm contacts the grinding disk and the end of the optical fiber sensor is under pressure, the length of the FP hollow cavity changes, and the spectral waveform drifts to the right. The pressure value exerted on the end of the optical fiber sensor at this time is obtained by the drift amount of a certain peak of the spectral waveform. When the optical fiber FP sensor reaches the preset pressure value, it is used as the initial point of grinding of the optical fiber sensor.

[0035] On the basis of the above technical solution, preferably, in the step of real-time monitoring of grinding thickness, the signal is processed by a demodulation algorithm, and the steps are as follows:

[0036] S21, performing fast Fourier transform on the dual FP interference signal to obtain two main peaks, and obtaining the FP hollow-core cavity amplitude-frequency characteristics and the FP solid-cavity amplitude-frequency characteristics after filter separation, performing inverse Fourier transform on the FP solid-cavity amplitude-frequency characteristics to obtain the FP solid-cavity interference spectrum signal, and performing inverse Fourier transform on the FP hollow-core cavity amplitude-frequency characteristics to obtain the FP hollow-core cavity interference spectrum signal;

[0037] S22, find the wavelength value corresponding to a peak through the peak-finding algorithm, and use the above formula , then the pressure value on the end of the optical fiber sensor at this time can be obtained by using the drift of the peak of the spectrum waveform;

[0038] S23, filtering the obtained FP solid cavity interference spectrum signal using a filter to obtain an interference signal at a specific wavelength;

[0039] S24, during the grinding process, the spectral signal changes due to the reduction of the cavity length of the FP solid cavity, and the spectral signal generated in this process is pre-processed by standardization and normalization to obtain a spectral signal with equal amplitude everywhere, and the spectral signal after pre-processing is denoised to obtain a smooth spectral signal;

[0040] S25, use the peak-finding algorithm to detect whether an envelope has two peaks, remove the redundant peaks, and obtain the actual envelope number ;

[0041] S26, through the thickness calculation formula Get the real-time thickness of the film during the grinding process;

[0042] In the formula, To measure the initial thickness of the FP solid cavity by microscope, is the expression for the reduction of cavity length of FP solid cavity during grinding; is the refractive index of the medium of the FP solid cavity, is the interference order, that is, the actual number of envelopes generated by the FP sensor during the grinding process.

[0043] On the other hand, the present invention proposes a grinding processing device, which is applied to the above-mentioned optical fiber grinding method, comprising a three-axis displacement mechanism, a grinding disc, a module frame, a clamping assembly and an adjustment locking member, wherein the three-axis displacement mechanism is arranged on one side of the grinding disc; the module frame is a cylindrical structure, and the peripheral surface of the module frame is divided into a plane and an arc surface, and the plane is connected to the three-axis displacement mechanism; a plurality of clamping assemblies are arranged around the arc surface and plugged into the module frame, and the clamping assembly is used to clamp the optical fiber sensor; the adjustment locking member is arranged on the module frame, and the adjustment locking member is used to keep the clamping assembly at a grinding height or a standby height; when the grinding disc grinds the optical fiber, the optical fiber spectrum information is detected by the demodulation system and converted into an electrical signal, and the electrical signal is transmitted to the host computer so as to control the feed amount of the three-axis displacement mechanism through the host computer; when the cavity length of any optical fiber sensor reaches the target thickness, the adjustment locking member pops up to clamp the clamping assembly of the optical fiber sensor, and the corresponding clamping assembly is located at the standby height.

[0044] On the basis of the above technical scheme, preferably, the module rack includes a cylinder, a partition, a sleeve and a cover plate, wherein the plane and the arc surface are arranged on the cylinder; the partition is arranged in the cylinder to divide the inner cavity of the cylinder into a top cavity and a bottom cavity; the sleeve passes through the partition, and the clamping assembly is plugged into the sleeve; the cover plate is arranged on the cylinder to seal the top cavity, and the cover plate is provided with a first slot corresponding to the sleeve; the adjusting locking member is arranged in the top cavity, and the adjusting end of the adjusting locking member passes through the cover plate.

[0045] On the basis of the above technical scheme, preferably, the clamping assembly includes a fixed seat, an inner tube, a bolt, a bottom clamp, a core and a top clamp, wherein the fixed seat is inserted in the sleeve, and a first opening is provided on one side of the fixed seat; the inner tube is arranged in the fixed seat, and the inner tube is provided with a second opening corresponding to the first opening; the bolt is threadedly connected to the fixed seat, and the bolt passes through the fixed seat and holds the inner tube; the bottom clamp is arranged at the lower end of the inner tube, the core is arranged in the bottom clamp, and the core is inserted in the inner tube, and a third opening is provided corresponding to the second opening; the bottom clamp is used to squeeze the core to clamp a point of the optical fiber sensor; the top clamp is arranged at the upper end of the inner tube, and the top clamp is used to clamp a point of the optical fiber sensor and control the feeding of the optical fiber sensor.

[0046] On the basis of the above technical scheme, preferably, the bottom clamp includes a cone clamp and a cone sleeve, and the insert core includes a continuous plug-in section, a transition section and a clamping section, wherein the bottom end of the inner tube is provided with a first cone surface and a first positioning groove; the plug-in section is inserted in the first positioning groove, and the transition section is provided with a second cone surface continuous with the first cone surface, and the transition section and the clamping section are both located on the outside of the inner tube; the cone clamp sleeve is provided on the insert core, the top surface of the cone clamp abuts against the first cone surface, and a gap is left between the inner wall of the cone clamp and the transition section and the clamping section; a plurality of second notches are provided on the circumferential surface of the cone clamp to form a plurality of arc plates, one of which closes the side of the third opening; the cone sleeve is provided on the inner tube and the cone clamp, and the cone sleeve is connected to the inner tube by a thread; when the cone sleeve is tightened, the cone clamp contacts the end of the clamping section away from the inner tube.

[0047] On the basis of the above technical scheme, preferably, the top clamp includes a clamping seat, a clamping plate, a first spring, a first clamping roller, a second clamping roller and a rotating member, wherein the clamping seat is provided with a second positioning groove, and the clamping seat is provided with a through groove corresponding to the second opening, so as to divide the clamping seat into a connected fixed plate and a positioning plate; the end of the inner tube away from the bottom clamp is inserted into the second positioning groove; the positioning plate is provided with a boss and a slot, and the middle section of the clamping plate is rotatably connected to the boss; one end of the first spring is inserted into the slot, and the other end abuts against the lower end of the clamping plate, and the second positioning groove is provided with a flat portion corresponding to the slot; the first clamping roller is rotatably arranged on the fixed plate; the second clamping roller is rotatably connected to the clamping plate through a rotating member, and the second clamping roller and the rotating member are relatively circumferentially limited.

[0048] On the basis of the above technical scheme, preferably, the adjustment locking member includes a second spring, a rotating shaft, a pressure cover, a lever, a servo, a limit rod and a limit block, wherein the second spring is arranged in the sleeve; the rotating shaft is arranged on the partition; the middle section of the pressure cover is rotatably connected to the rotating shaft; the lever is arranged on one end of the pressure cover, and the lever passes through the cover plate, and the cover plate is provided with an arc groove corresponding to the lever; the servo is arranged on the partition; the limit rod is connected to the main shaft of the servo; the limit block is arranged on the servo; when the grinding processing device is grinding, the limit block limits the limit rod, and the pressure cover closes the top end of the sleeve, so that the clamping assembly maintains the grinding height; when the grinding processing device finishes grinding, the limit rod is in the adjustment position, the pressure cover releases the seal on the sleeve, and the second spring pops up the clamping assembly, so that the clamping assembly maintains the standby height.

[0049] The optical fiber polishing method and polishing device of the present invention have the following beneficial effects compared with the prior art:

[0050] (1) This processing method uses the FP sensor diaphragm thickness demodulation algorithm to convert the interference spectrum signal into the frequency domain through discrete Fourier transform, separates and identifies the spectral signal of the solid cavity (diaphragm) at a specific wavelength using filter technology, and converts the signal back to the time domain through inverse Fourier transform, performs standardization and denoising processing to smooth the spectrum and accurately find the peak, and then calculates the real-time thickness of the solid cavity (diaphragm) through a theoretical formula; in this way, online monitoring of the cavity length thickness during the grinding process is achieved, thereby achieving grinding control of a single optical fiber, while ensuring the grinding processing accuracy and efficiency of the optical fiber;

[0051] (2) The grinding processing device is provided with an adjustable locking member, which can control the position of the clamping assembly. In this way, when it is determined that a single optical fiber has reached the target grinding thickness through the coordinated action of the demodulation system and the host computer, the adjustable locking member can adjust the corresponding clamping assembly to the standby height to prevent the optical fiber from continuing to be ground; while the optical fibers on other clamping assemblies continue to be ground until the target thickness is reached; in this way, the device realizes precise thickness control when grinding multiple optical fibers at the same time, improves processing accuracy, and ensures grinding efficiency;

[0052] (3) The module frame for installing the clamping assembly is composed of a cylinder, a partition, a sleeve and a cover plate, and the whole structure is a hollow structure. In this way, when the three-axis displacement mechanism drives the module frame to move, the load inertia can be reduced to ensure the displacement accuracy of the three-axis displacement mechanism, thereby ensuring the optical fiber grinding processing accuracy;

[0053] (4) The clamping assembly is provided with a top clamp and a bottom clamp, which can perform double-point clamping on the optical fiber sensor to reduce the shaking of the optical fiber sensor, thereby fully ensuring the clamping stability; at the same time, the top clamp is also used to control the feed of the optical fiber sensor, so that the clamping positioning and feed control are realized simultaneously, which can ensure that the optical fiber sensor has a precise feed amount to ensure the processing accuracy;

[0054] (5) The bottom clamp of the clamping assembly includes a cone clamp and a cone sleeve, and a core is arranged in the bottom clamp. During assembly, the cone clamp matches the first cone surface of the inner tube and leaves a gap between the cone clamp and the core. Only when the cone sleeve is installed for clamping and fixing, the end of the cone clamp will contact the end of the core. This can prevent the problem of uneven clamping force of the optical fiber sensor due to excessive contact surface, so as to avoid affecting the processing accuracy. The core is a detachable structure, which is convenient for maintenance and replacement, and also convenient for structural or material adjustments based on the adaptability of the optical fiber.

[0055] In the adjustment locking piece, the clamping assembly is pressed and fixed by a pressure cover, and the positioning is achieved by the limit rod and the limit block on the servo. After the optical fiber meets the grinding requirements, the servo can rotate the limit rod to make the pressure cover release the pressure on the clamping assembly. At this time, the clamping assembly will be bounced up by the second spring and maintained at the standby height to avoid further grinding, thereby ensuring the grinding accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 It is a flow chart of the demodulation algorithm of the present invention;

[0058] Figure 2 It is a schematic diagram of the operation flow structure of the monitoring system of the present invention;

[0059] Figure 3 is a flow chart of the motor control system of the present invention;

[0060] Figure 4 It is a system diagram of the online grinding solution of the present invention;

[0061] Figure 5 is a perspective view of the grinding processing device of the present invention;

[0062] Figure 6 A perspective view of a module frame of a grinding processing device of the present invention;

[0063] Figure 7 A bottom perspective view of a module frame of a grinding processing device of the present invention;

[0064] Figure 8 A top view of the grinding device of the present invention;

[0065] Fig. 9 For the present invention Figure 8 Middle AA section view;

[0066] Fig.10 It is a disassembled structural diagram of the module frame and the clamping assembly of the grinding processing device of the present invention;

[0067] Fig.11 A three-dimensional diagram of a clamping assembly of a grinding processing device of the present invention;

[0068] Fig.12 It is a side structural diagram of the clamping assembly of the grinding processing device of the present invention;

[0069] Fig.13 An exploded view of a clamping assembly of the grinding processing device of the present invention;

[0070] Fig.14 It is a connection diagram of the inner tube and the fixing seat in the clamping assembly of the grinding processing device of the present invention;

[0071] Fig.15 It is a structural diagram of the cone clamp and the core of the grinding processing device of the present invention;

[0072] Fig.16 It is an exploded structural side view of the clamping assembly of the grinding processing device of the present invention;

[0073] Fig.17 It is a front view of the clamping assembly of the grinding processing device of the present invention;

[0074] Fig.18 For the present invention Fig.17 Middle BB section;

[0075] Fig.19 For the present invention Fig.18 A magnified view of the structure at point A;

[0076] Fig. 20 It is an exploded structural diagram of the top clamp of the grinding processing device of the present invention;

[0077] Fig.21 It is an assembly structure diagram of the adjustment locking member of the grinding processing device of the present invention;

[0078] Fig. 22 A structural diagram of a module frame of a grinding processing device of the present invention provided with an elastic sheet;

[0079] Fig.23 A structural diagram of a fixing seat of the grinding processing device of the present invention having an embedding groove;

[0080] Fig.24 is a flow chart of the preparation of the optical fiber FP sensor of the present invention;

[0081] In the figure: 1, three-axis displacement mechanism; 11, X-axis slide; 12, Z-axis slide; 13, Y-axis slide; 2, grinding disc; 3, module frame; 31, cylinder; 32, partition; 33, sleeve; 34, cover plate; 35, elastic sheet; 301, plane; 302, arc surface; 303, top cavity; 304, bottom cavity; 305, first notch; 306, arc groove; 307, guide groove; 4, clamping assembly; 401, gap; 402, embedded groove; 41, fixed seat; 4101, first opening; 42, inner tube; 4201, second opening; 4202, first cone surface; 4203, first positioning groove; 4204, second positioning hole; 43, bolt; 44, bottom clamp; 441, cone clamp; 4411, arc plate; 442, cone sleeve; 4401, first two notches; 45, insert; 451, plug-in section; 452, transition section; 453, clamping section; 4501, third opening; 4502, second conical surface; 4503, first positioning hole; 46, top clamp; 461, clamp seat; 4611, fixing plate; 4612, positioning plate; 46121, boss; 462, clamping plate; 463, first spring; 464, first clamping roller; 465, second clamping roller; 466, rotating member; 4601, second positioning groove; 46011, plane part; 4602, through groove; 4603, slot; 5, adjusting locking member; 51, second spring; 52, rotating shaft; 53, pressure cover; 54, lever; 55, servo; 56, limit rod; 57, limit block; 6, displacement sensor; 7, vibration isolation table; 8, industrial camera. DETAILED DESCRIPTION

[0082] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0083] like Figures 1 to 24 As shown, the grinding processing device of the present invention includes a three-axis displacement mechanism 1, a grinding disc 2, a module frame 3, a clamping assembly 4, an adjustment locking member 5, a displacement sensor 6, a vibration isolation table 7 and an industrial camera 8.

[0084] like Figures 5 to 10 As shown, the three-axis displacement mechanism 1 is arranged on one side of the grinding disc 2; the module frame 3 is a cylindrical structure, and the peripheral surface of the module frame 3 is divided into a plane 301 and an arc surface 302, and the plane 301 is connected to the three-axis displacement mechanism 1; a plurality of clamping assemblies 4 are arranged around the arc surface 302 and plugged with the module frame 3, and the clamping assemblies 4 are used to clamp the optical fiber sensor;

[0085] As in the above structure, when used, the optical fiber sensor is clamped by the clamping assembly 4, and the clamping assembly 4 is assembled on the module frame 3, so that the clamping assembly 4 and the optical fiber sensor can be moved by the three-axis displacement mechanism 1, so that the optical fiber sensor is close to the grinding disc 2, and the optical fiber sensor is ground by the grinding disc 2;

[0086] Among them, the three-axis displacement mechanism 1 adopts a screw slide, which is specifically divided into an X-axis slide 11, a Z-axis slide 12 and a Y-axis slide 13; the X-axis slide 11 and the grinding disc 2 are both arranged on a vibration isolation table 7 to reduce the vibration occurring during the grinding process through the vibration isolation table 7.

[0087] Specifically, the X-axis slide 11 and the Z-axis slide 12 use electric slides driven by motors, while the Y-axis slide 13 uses a manual slide. When constructing the Y-axis slide 13, a lead screw is used to cooperate with the module frame 3 through threads, and one end of the lead screw is supported against the Z-axis slide 12. In this way, when the lead screw is rotated, the module frame 3 will be displaced relative to the Z-axis slide 12; at the same time, a slide rail is also provided between the module frame 3 and the sliding part of the Z-axis slide 12, so as to play a load-bearing role and circumferentially position the module frame 3.

[0088] like Fig. 9 and Fig.10 As shown, the adjustment locking member 5 is arranged on the module frame 3, and the adjustment locking member 5 is used to keep the clamping assembly 4 at the grinding height or the standby height;

[0089] As in the above structure, the adjusting locking member 5 is used to adjust the height of the clamping assembly 4 so that the optical fiber sensor can be selectively moved closer to or away from the grinding disc 2;

[0090] In the present grinding processing device, one side of the grinding disc 2 is set as a plane 301, so that it is convenient to connect with the three-axis displacement mechanism 1, and the grinding disc 2 is also provided with an arc surface 302, so that it is convenient to arrange multiple clamping components 4 to clamp multiple optical fiber sensors at the same time, thereby realizing synchronous grinding of multiple optical fiber sensors;

[0091] Due to different clamping positions and different deformations caused by grinding, vibration and other factors, it is difficult for multiple optical fiber sensors to meet the grinding requirements at the same time. Therefore, an adjustment locking member 5 is provided. After a single optical fiber sensor meets the grinding requirements, the adjustment locking member 5 will adjust the clamping assembly of the optical fiber sensor that meets the requirements to the standby height to avoid over-grinding and affect its accuracy, and will not interfere with the continued grinding of other optical fiber sensors.

[0092] When the grinding processing device is used, when the grinding disc 2 grinds the optical fiber, the optical fiber spectrum information is detected by the demodulation system and converted into an electrical signal, and the electrical signal is transmitted to the host computer so as to control the feed amount of the three-axis displacement mechanism 1 through the host computer; when the cavity length of any optical fiber sensor reaches the target thickness, the locking member 5 is adjusted to pop up the clamping assembly 4 that clamps the optical fiber sensor, and the corresponding clamping assembly 4 is located at the standby height;

[0093] As described above, the structure realizes online monitoring of the fiber optic sensor grinding. That is, when it is detected that the cavity length of the fiber optic sensor reaches the grinding thickness, the corresponding clamping assembly 4 will be adjusted to pop up the locking part 5 to keep the fiber optic sensor away from the grinding disk to prevent over-grinding, thereby ensuring the processing accuracy.

[0094] like Figures 6 to 9 As shown, the module rack 3 includes a cylinder 31, a partition 32, a sleeve 33 and a cover plate 34, wherein the plane 301 and the arc surface 302 are arranged on the cylinder 31, and the cylinder 31 is connected to the three-axis displacement mechanism 1; the partition 32 is arranged in the cylinder 31, and the inner cavity of the cylinder 31 is divided into a top cavity 303 and a bottom cavity 304; the sleeve 33 passes through the partition 32, and the clamping assembly 4 is plugged into the sleeve 33; the cover plate 34 is arranged on the cylinder 31 to seal the top cavity 303, and the cover plate 34 is provided with a first notch 305 corresponding to the sleeve 33; the adjustment locking member 5 is arranged in the top cavity 303, and the adjustment end of the adjustment locking member 5 passes through the cover plate 34.

[0095] As shown in the above structure, the module rack 3 is composed of a cylinder 31, a partition plate 32, a sleeve 33 and a cover plate 34, and the whole is a hollow structure. In this way, when the three-axis displacement mechanism 1 drives the module rack 3 to move, the load inertia can be reduced to ensure the displacement accuracy of the three-axis displacement mechanism 1, and then ensure the optical fiber grinding processing accuracy;

[0096] When assembling the clamping assembly 4, the clamping assembly 4 is inserted into the sleeve 33, and then the clamping assembly 4 is kept at the grinding height by the adjusting locking member 5 on the partition 32, and the optical fiber sensor is installed on the clamping assembly 4, and then the three-axis displacement mechanism 1 can be used to drive the displacement to perform the grinding work;

[0097] Specifically, in this structure, the partition plate 32 supports the adjustment locking member 5 and also strengthens the structure of the cylinder 31 and the sleeve 33, thereby ensuring the lightweight of the module rack 3 and the structural strength;

[0098] In order to ensure the accuracy of the adjustment locking member 5, a cover plate 34 is provided on the cylinder 31 for sealing the top cavity 303 to close the adjustment locking member 5. In order to avoid interference of the adjustment locking member 5 when the clamping assembly 4 is adjusted to the standby height, and to facilitate the disassembly and assembly of the clamping assembly 4, the cover plate 34 is provided with a first notch 305 corresponding to the adjustment locking member 5.

[0099] like Figures 11 to 19 As shown, the clamping assembly 4 includes a fixing seat 41, an inner tube 42, a bolt 43, a bottom clamp 44, an insert 45 and a top clamp 46, wherein the fixing seat 41 is inserted into the sleeve 33, and a first opening 4101 is provided on one side of the fixing seat 41; the inner tube 42 is provided in the fixing seat 41, and a second opening 4201 is provided on the inner tube 42 corresponding to the first opening 4101; the bolt 43 is threadedly connected to the fixing seat 41, and the bolt 43 passes through the fixing seat 41 and abuts against the inner tube 42;

[0100] As in the above structure, the fixing seat 41 is connected to the sleeve 33, and the fixing seat 41 is used to pass the optical fiber sensor; when assembling, the fixing seat 41 is installed into the sleeve 33, and then the bolt 43 is passed through the fixing seat 41 and abuts against the inner tube 42, so that the inner tube 42 can be fixed;

[0101] In order to facilitate observation of the state of the optical fiber sensor, the fixing base 41 is provided with a first opening 4101 , and the inner tube 42 is correspondingly provided with a second opening 4201 .

[0102] The bottom clamp 44 is arranged at the lower end of the inner tube 42, the ferrule 45 is arranged in the bottom clamp 44, and the ferrule 45 is plugged with the inner tube 42, and a third opening 4501 is arranged corresponding to the second opening 4201; the bottom clamp 44 is used to squeeze the ferrule 45 to clamp a point of the optical fiber sensor; the top clamp 46 is arranged at the upper end of the inner tube 42, and the top clamp 46 is used to clamp a point of the optical fiber sensor and control the feeding of the optical fiber sensor;

[0103] As in the above structure, the bottom clamp 44 and the top clamp 46 are each used to clamp a point of the optical fiber sensor, and the top clamp 46 is also used to feed the optical fiber sensor to facilitate the adjustment of the position of the optical fiber sensor. After the top clamp 46 has adjusted the position of the optical fiber sensor, the bottom clamp 44 and the top clamp 46 can then lock the optical fiber sensor.

[0104] The bottom clamp 44 does not clamp the optical fiber sensor directly, but clamps the optical fiber sensor through the ferrule 45 inside it. In this way, when it is used, by replacing the ferrule 45 and using ferrules 45 of different shapes or materials, it is possible to achieve the clamping and grinding of various optical fiber sensors, thereby improving the application range of the device; correspondingly, the ferrule 45 is provided with a third opening 4501 to facilitate the insertion of the optical fiber sensor;

[0105] The above-mentioned structure can effectively solve the problem of enlargement of the hollow cavity caused by the optical fiber fusion splicing process and the problem that the existing optical fiber adapter is unable to insert the optical fiber for clamping, thereby ensuring the applicability.

[0106] like Figures 13 to 19As shown, the bottom clamp 44 includes a cone clamp 441 and a cone sleeve 442, and the insert core 45 includes a continuous plug-in section 451, a transition section 452 and a clamping section 453, wherein the bottom end of the inner tube 42 is provided with a first cone surface 4202 and a first positioning groove 4203; the plug-in section 451 is plugged into the first positioning groove 4203, and the transition section 452 is provided with a second cone surface 4502 continuous with the first cone surface 4202, and the transition section 452 and the clamping section 453 are both located on the outside of the inner tube 42; the cone clamp 441 is sleeved on the insert core 45, and the cone clamp 44 1 abuts against the first conical surface 4202, and a gap 401 is left between the inner wall of the cone clamp 441 and the transition section 452 and the clamping section 453; a plurality of second notches 4401 are provided on the circumference of the cone clamp 441 to form a plurality of arc plates 4411, one of which closes the side of the third opening 4501; the cone sleeve 442 is sleeved on the inner tube 42 and the cone clamp 441, and the cone sleeve 442 is connected to the inner tube 42 by threads; when the cone sleeve 442 is tightened, the ends of the cone clamp 441 and the clamping section 453 away from the inner tube 42 are in contact.

[0107] As in the above structure, when the bottom clamp 44 is assembled, the plug core 45 is plugged into the first positioning groove 4203 of the inner tube 42 through the plug section 451, so that when the cone clamp 441 and the cone sleeve 442 are tightened, the plug core 45 can be limited to prevent the plug core 45 from sliding;

[0108] Specifically, the inner tube 42 is provided with a first conical surface 4202, and the insert 45 realizes a smooth transition with the end of the inner tube 42 through the second conical surface 4502 of the transition section 452; at this time, when the cone clamp 441 is assembled, it is configured as a conical cylindrical structure, so that when the cone clamp 441 abuts against the first conical surface 4202, the insert 45 is limited due to the taper of the inner wall to prevent the insert 45 from sliding down;

[0109] See Fig.15 and Fig.19 A first positioning hole 4503 is provided on the insert 45, and a second positioning hole 4204 is provided on the inner tube 42. In this way, when the insert 45 is limited, the pin is passed through the first positioning hole 4503 and the second positioning hole 4204 for positioning; then the two positioning holes are closed on the installation cone sleeve 442.

[0110] In some embodiments, the cone clamp 441 may also have a portion of the top wall that abuts against the second cone surface 4502 to achieve axial limitation of the insert 45 .

[0111] See Fig.19When the above components are arranged, a gap 401 is formed between the cone clamp 441 and the ferrule 45, so that the contact area between the cone clamp 441 and the ferrule 45 can be minimized. Only when the cone sleeve 442 is tightened, the cone clamp 441 will be squeezed so that the end of the cone clamp 441 clamps the ferrule 45, and the ferrule 45 fixes the optical fiber sensor passing through. In this way, the contact area between the cone clamp 441 and the ferrule 45 can be effectively reduced to prevent the ferrule 45 from being subjected to uneven force and unstable clamping.

[0112] See Fig.15 When the cone clamp 441 is arranged, the cone clamp 441 forms a plurality of arc plates 4411 by opening the second notch 4401, so that when the cone sleeve 442 is tightened, the second notch 4401 becomes smaller, so that the arc plates 4411 can clamp the ferrule 45;

[0113] In order to ensure that the third opening 4501 of the insert 45 can be stably locked, an arc plate 4411 in the cone clamp 441 closes the third opening 4501. The arc plate 4411 is an arc-shaped plate, that is, the arc length spanned by a single arc plate 4411 is greater than the arc length spanned by the third opening 4501.

[0114] like Fig.10 and Fig. 20 As shown, the top clamp 46 includes a clamp seat 461, a clamp plate 462, a first spring 463, a first clamp roller 464, a second clamp roller 465 and a rotating member 466, wherein the clamp seat 461 is provided with a second positioning groove 4601, and the clamp seat 461 is provided with a through groove 4602 corresponding to the second opening 4201, so as to divide the clamp seat 461 into a connected fixed plate 4611 and a positioning plate 4612; the end of the inner tube 42 away from the bottom clamp 44 is inserted into the second positioning groove 4601; the positioning plate 4612 is provided with a boss 46121 and the slot 4603, the middle section of the clamping plate 462 is rotatably connected with the boss 46121; one end of the first spring 463 is inserted into the slot 4603, and the other end abuts against the lower end of the clamping plate 462, and the second positioning groove 4601 is provided with a flat portion 46011 corresponding to the slot 4603; the first clamping roller 464 is rotatably set on the fixed plate 4611; the second clamping roller 465 is rotatably connected with the clamping plate 462 through the rotating member 466, and the second clamping roller 465 and the rotating member 466 are relatively circumferentially limited;

[0115] As in the above structure, when the top clamp 46 is used, the optical fiber sensor passes between the first clamping roller 464 and the second clamping roller 465, and the through groove 4602 on the top clamp 46 is used to pass the optical fiber sensor; at this time, under the action of the first spring 463, the second clamping roller 465 will apply a force to resist the first clamping roller 464, thereby clamping the optical fiber sensor;

[0116] When the optical fiber sensor needs to be fed, the second clamping roller 465 is driven to rotate by the rotating member 466, and the first clamping roller 464 rotates relatively, so that the optical fiber sensor can be fed;

[0117] Specifically, the clamping seat 461 and the clamping plate 462 are used to install the first clamping roller 464 and the second clamping roller 465. In order to ensure the compactness of the top clamp 46, the clamping seat 461 is divided into two parts: a fixing plate 4611 and a positioning plate 4612. A boss 46121 is provided on the positioning plate 4612 for connecting the clamping plate 462, so that the maximum width of the clamping plate 462 and the clamping seat 461 can be the same;

[0118] Furthermore, the inner tube 42 is inserted into the second positioning groove 4601 away from the bottom clamp 44, and the second positioning groove 4601 is provided with a flat portion 46011 corresponding to the slot 4603 for installing the first spring 463. Such a structural setting reduces the diameter of the second positioning groove 4601, leaving space for opening the slot 4603, further ensuring the compactness of the structure, and also realizing the circumferential limitation of the top clamp 46 relative to the inner tube 42.

[0119] like Fig.21 As shown, the adjustment locking member 5 includes a second spring 51, a rotating shaft 52, a pressure cover 53, a lever 54, a steering gear 55, a limiting rod 56 and a limiting block 57, wherein the second spring 51 is arranged in the sleeve 33; the rotating shaft 52 is arranged on the partition 32; the middle section of the pressure cover 53 is rotatably connected with the rotating shaft 52; the lever 54 is arranged on one end of the pressure cover 53, and the lever 54 passes through the cover plate 34, and the cover plate 34 is provided with an arc groove 306 corresponding to the lever 54; the steering gear 55 is arranged on the partition 32; the limiting rod 56 is connected with the main shaft of the steering gear 55; the limiting block 57 is arranged on the steering gear 55;

[0120] When the grinding device is grinding, the limit block 57 limits the limit rod 56, and the pressure cover 53 closes the top of the sleeve 33, so that the clamping assembly 4 maintains the grinding height; when the grinding device finishes grinding, the limit rod 56 is in the adjustment position, the pressure cover 53 releases the seal on the sleeve 33, and the second spring 51 bounces up the clamping assembly 4, so that the clamping assembly 4 maintains the standby height;

[0121] As in the above structure, after the clamping assembly 4 is inserted into the sleeve 33, the bottom end will abut against the second spring 51. At this time, the clamping assembly 4 is pressed to compress the second spring 51, and then the pressure cover 53 is driven to rotate by the lever 54 until the lever 54 abuts against the limit rod 56. At this time, the pressure cover 53 closes the opening of the sleeve 33, so that the clamping assembly 4 and the optical fiber sensor are located at the grinding height;

[0122] When a certain optical fiber sensor reaches the grinding target thickness, the steering gear 55 is actuated to drive the limit rod 56 to rotate, thereby toggling the lever 54. At this time, the lever 54 drives the pressure cover 53 to move and separate from the top of the sleeve 33. At this time, under the action of the second spring 51, the clamping assembly 4 and the optical fiber sensor will be bounced up to maintain the standby height to avoid further grinding;

[0123] In this structure, a limit block 57 is provided to limit the limit rod 56, which can avoid the problem that the lever 54 over-displaces and hits the limit rod 56 when pressing the clamping assembly 4, causing the steering gear 55 to be misaligned;

[0124] In some embodiments, the size of the arc groove 306 can be controlled to prevent the lever 54 from over-displacing; however, the arc groove 306 is difficult to calibrate with the servo 55, so preferably, a limit block 57 is directly provided on the housing of the servo 55.

[0125] like Figure 5 , Figures 7-9 As shown, for this grinding processing device, a displacement sensor 6 and an industrial camera 8 are also provided; wherein the industrial camera 8 adopts a CCD camera to observe the state of the optical fiber sensor during grinding; wherein the displacement sensor 6 adopts a laser sensor to detect the axial position change between the module frame 3 and the grinding disc 2, and feeds back to the host computer to facilitate the control of the axial displacement of the module frame 3 and the optical fiber sensor. This structure can solve the problem of axial runout of the grinding disc. When the grinding disc 2 runs axially, the Z-axis slide 12 in the three-axis displacement mechanism 1 can move synchronously to achieve runout compensation.

[0126] like Fig. 22 and Fig.23 As shown, in some embodiments, a guide groove 307 is provided on the module frame 3, an elastic sheet 35 is arranged in the guide groove 307, and an embedding groove 402 is provided on the fixed seat 41, and the elastic sheet 35 is arranged at a position corresponding to the standby height. When the clamping component 4 is popped up, the elastic sheet 35 is snapped into the embedding groove 402, thereby achieving stable positioning of the clamping component 4, thereby preventing the clamping component 4 from being continuously bounced up and down to cause vibration and affect the processing accuracy.

[0127] The optical fiber polishing method of the present invention uses the above-mentioned polishing device and comprises the following steps:

[0128] S11, setting the three-axis displacement mechanism 1 and the grinding disc 2 for optical fiber grinding, and using the host computer to electrically control the three-axis displacement mechanism 1 and the grinding disc 2,

[0129] S12, a clamping assembly 4 is arranged on the three-axis displacement mechanism 1, and an optical fiber sensor is installed on the clamping assembly 4, and the three-axis displacement mechanism 1 drives the optical fiber sensor to move closer to or away from the grinding disc 2,

[0130] S13, when the optical fiber sensor is close to the grinding disc 2, determining the initial grinding point, and grinding the end of the optical fiber sensor by the grinding disc 2;

[0131] Among them, Figure 4 As shown, during the grinding process, a demodulation system is composed of a broadband light source, an optical circulator and a spectrometer to detect the optical fiber spectrum information and convert it into an electrical signal, which is transmitted to the host computer. The host computer monitors the grinding thickness in real time through the demodulation algorithm, and establishes communication with the three-axis displacement mechanism 1 and the grinding disc 2 through the hardware module, and then controls the action of the three-axis displacement mechanism 1 and the grinding disc 2 according to the grinding thickness detection information.

[0132] In the present invention, the grinding thickness is calculated by the number of peaks, and the steps are as follows:

[0133] The optical fiber sensor is set up, and the sensor diaphragm is regarded as a solid cavity. The three reflection surfaces form two FP cavities. The incident light is reflected and transmitted to different degrees between the three reflection surfaces. Finally, the reflected light is superimposed and interfered with each other to form a spectrum. The three reflection surfaces are recorded as M1, M2 and M3 respectively. The intensity of the reflected light formed after the interference is expressed as:

[0134]

[0135] Where: is the output light intensity; , , are the reflectivities at the reflection surfaces M1, M2 and M3 respectively; is the output wavelength; , is the refractive index of the medium of the FP solid cavity and the FP hollow cavity; , are the cavity lengths of the FP solid cavity and the FP hollow cavity, respectively; is the ratio of pi; is the cosine function;

[0136] The interference signal of the FP solid cavity is:

[0137]

[0138] In the formula, , are the reflectivities at the reflection surfaces M1 and M2 respectively; is the refractive index of the medium of the FP solid cavity; is the cavity length of the FP solid cavity; is the ratio of pi; is the cosine function; is the output wavelength;

[0139] Considering the half-wave loss, the initial phase is , when the phase difference When the interference is destructive, the expression for the reduction of the cavity length of the FP solid cavity during the grinding process is:

[0140]

[0141] In the formula, is the interference order, i.e., the actual number of envelopes generated by the FP sensor during the grinding process; is the refractive index of the medium of the FP solid cavity, ; is the output wavelength; is the reduction in cavity length of the FP solid cavity; is the ratio of pi;

[0142] The grinding thickness is monitored in real time by the reduction of cavity length.

[0143] In the present invention, the initial grinding point is determined by the change in the length of the FP hollow core cavity after being pressurized, and the steps are as follows:

[0144] According to the definition of Young's modulus:

[0145]

[0146] Where, E is Young's modulus; F is the applied pressure; S is the area of ​​the effective force-bearing cross section; L is the length of the FP hollow cavity; is the change in the length of the FP hollow core cavity; this equation can be transformed into:

[0147]

[0148] Where, E is Young's modulus; F is the applied pressure; S is the area of ​​the effective force-bearing cross section; L is the length of the FP hollow cavity; is the change in the length of the FP hollow core cavity;

[0149] When the pressure on the grinding disc 2 changes, the length of the hollow core cavity of the optical fiber sensor FP will also change. When the structural parameters of the optical fiber sensor are determined, E, S, and L in the formula are determined values, and the change in the length of the hollow core cavity of FP is proportional to the pressure on the optical fiber.

[0150] According to the above formula,

[0151] ,

[0152] When the sensor diaphragm contacts the grinding disk 2 and the end of the optical fiber sensor is pressurized, the length of the FP hollow cavity changes, and the spectral waveform drifts to the right. The pressure value exerted on the end of the optical fiber sensor at this time is obtained by the drift amount of a certain peak of the spectral waveform. When the optical fiber FP sensor reaches the preset pressure value, it serves as the initial point of grinding of the optical fiber sensor.

[0153] In the present invention, Figure 1 As shown, in the step of real-time monitoring of grinding thickness, the signal is processed by a demodulation algorithm, and the steps are as follows:

[0154] S21, performing fast Fourier transform on the dual FP interference signal to obtain two main peaks, and obtaining the FP hollow-core cavity amplitude-frequency characteristics and the FP solid-cavity amplitude-frequency characteristics after filter separation, performing inverse Fourier transform on the FP solid-cavity amplitude-frequency characteristics to obtain the FP solid-cavity interference spectrum signal, and performing inverse Fourier transform on the FP hollow-core cavity amplitude-frequency characteristics to obtain the FP hollow-core cavity interference spectrum signal;

[0155] S22, find the wavelength value corresponding to a peak through the peak-finding algorithm, and use the above formula , then the pressure value on the end of the optical fiber sensor at this time can be obtained by using the drift of the peak of the spectrum waveform;

[0156] S23, filtering the obtained FP solid cavity interference spectrum signal using a filter to obtain an interference signal at a specific wavelength;

[0157] S24, during the grinding process, the spectral signal changes due to the reduction of the cavity length of the FP solid cavity, and the spectral signal generated in this process is pre-processed by standardization and normalization to obtain a spectral signal with equal amplitude everywhere, and the spectral signal after pre-processing is denoised to obtain a smooth spectral signal;

[0158] S25, use the peak-finding algorithm to detect whether an envelope has two peaks, remove the redundant peaks, and obtain the actual envelope number ;

[0159] S26, through the thickness calculation formula Get the real-time thickness of the film during the grinding process;

[0160] In the formula, To measure the initial thickness of the FP solid cavity by microscope, is the expression for the reduction of cavity length of FP solid cavity during grinding; is the refractive index of the medium of the FP solid cavity, is the interference order, that is, the actual number of envelopes generated by the FP sensor during the grinding process.

[0161] like Fig.24As shown, in the present invention, the optical fiber sensor is an optical fiber FP sensor, and its preparation process is as follows:

[0162] Step 1: Fix the single-mode optical fiber and the hollow-core optical fiber at the fixed end of the optical fiber fusion splicer, and use the electrode discharge of the optical fiber fusion splicer to fuse the single-mode optical fiber and the hollow-core optical fiber to each other;

[0163] Step 2: Use a fiber cleaver to cut the other end of the hollow-core fiber after fusion under a microscope, and reduce the length of the hollow-core fiber at the same time;

[0164] Step 3: Fix the cut end of the hollow-core optical fiber and another single-mode optical fiber at the fixed end of the optical fiber fusion splicer, and use the electrode discharge of the optical fiber fusion splicer to fuse the two parts to obtain a hollow-core cavity;

[0165] Step 4: Use a fiber cleaver to cut the other end of the single-mode optical fiber after fusion in step 3 flat under a microscope, and reduce the length of the single-mode optical fiber to obtain a solid cavity, i.e., a diaphragm;

[0166] like Figure 2 and Fig.24 As shown, the optical fiber grinding and processing method of the present invention, the specific preparation of the optical fiber and the linkage between the components are as follows:

[0167] Step 1: Through the fiber cutting and fusion process, the single-mode fiber, hollow fiber, and single-mode fiber are spliced ​​in sequence, and the end single-mode fiber is partially removed by precision cutting to form a single-mode fiber diaphragm with a thickness of less than 1 mm.

[0168] Step 2: Use the fiber adapter to fix it on the fiber polishing device. Manually turn on the polishing device, and the host computer sends motion instructions to the Bluetooth module of Arduino. After receiving the instructions, Arduino parses the received instructions to control the stepper motor of the three-axis displacement mechanism to feed at a uniform speed according to the designed stepper motor control system.

[0169] Step 3: During the diaphragm grinding process, the spectrum information of the FP sensor diaphragm grinding process is converted into an electrical signal through a demodulation system composed of a broadband light source, an optical circulator, and a spectrometer, and then transmitted to the host computer;

[0170] Step 4: After receiving the electrical signal output by the spectrometer, the host computer uses the demodulation algorithm proposed in the present invention to find the number of peaks in the spectrum graph, calculates the membrane thickness value according to the theoretical formula, and sends the calculation result to Arduino via the Bluetooth module;

[0171] Step 5: After receiving the diaphragm thickness information, the Arduino controls the movement of the stepper motor of the three-axis displacement mechanism 1 and the steering gear 55 of the adjustment locking member 5 through the designed motor control system.

[0172] like Figure 3 As shown, it is a schematic diagram of the motor control process in this processing method;

[0173] The three-axis displacement mechanism 1 is driven by a stepper motor, and the stepper motor is provided with a rotary encoder for monitoring the actual shaft angle of the stepper motor to provide an accurate position feedback signal.

[0174] A PID controller is also provided, which generates a control signal through calculation of three links: proportional P, integral I and differential D according to the deviation between the feedback signal provided by the rotary encoder and the target shaft angle;

[0175] In the three-axis displacement mechanism 1, the X-axis slide 11 and the Z-axis slide 12 are driven by stepper motors, which receive control signals generated by a PID controller and adjust their step angles according to the signals to achieve precise feed control;

[0176] Likewise, the steering gear 55 adopts the same control method to ensure that its rotation angle is accurate, thereby ensuring that the pressure cover 53 can achieve stable positioning of the clamping assembly 4.

[0177] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for polishing an optical fiber, characterized in that: The following steps are involved: S11, setting a three-axis displacement mechanism (1) and a grinding disc (2) for optical fiber grinding, and electrically controlling the three-axis displacement mechanism (1) and the grinding disc (2) by a host computer, S12, arranging a clamping assembly (4) on the three-axis displacement mechanism (1), installing an optical fiber sensor on the clamping assembly (4), and the three-axis displacement mechanism (1) drives the optical fiber sensor to move closer to or farther away from the grinding disc (2), S13, when the optical fiber sensor is close to the grinding disc (2), determining an initial grinding point, and grinding the end of the optical fiber sensor with the grinding disc (2); In the grinding process, a demodulation system is composed of a broadband light source, an optical circulator and a spectrometer to detect optical fiber spectrum information and convert it into an electrical signal, which is transmitted to a host computer. The host computer monitors the grinding thickness in real time through a demodulation algorithm, establishes communication with the three-axis displacement mechanism (1) and the grinding disc (2) through a hardware module, and then controls the movement of the three-axis displacement mechanism (1) and the grinding disc (2) according to the grinding thickness detection information; A grinding processing device using the optical fiber grinding method comprises a three-axis displacement mechanism (1), a grinding disc (2), a module frame (3), a clamping assembly (4) and an adjustment locking member (5), wherein the three-axis displacement mechanism (1) is arranged on one side of the grinding disc (2); the module frame (3) is a cylindrical structure, the peripheral surface of the module frame (3) is divided into a plane (301) and an arc surface (302), and the plane (301) is connected to the three-axis displacement mechanism (1); a plurality of the clamping assemblies (4) are arranged around the arc surface (302) and are plugged into the module frame (3); the clamping assemblies (4) are arranged around the arc surface (302) and are plugged into the module frame (3); the clamping assemblies (4) are arranged around the arc surface (302) and are plugged into the module frame (3). ) is used to clamp the optical fiber sensor; the adjusting locking member (5) is arranged on the module frame (3), and the adjusting locking member (5) is used to keep the clamping assembly (4) at a grinding height or a standby height; when the grinding disc (2) grinds the optical fiber, the optical fiber spectrum information is detected by the demodulation system and converted into an electrical signal, and the electrical signal is transmitted to the host computer so as to control the feed amount of the three-axis displacement mechanism (1) through the host computer; when the cavity length of any optical fiber sensor reaches the target thickness, the adjusting locking member (5) pops up the clamping assembly (4) that clamps the optical fiber sensor, and the corresponding clamping assembly (4) is located at the standby height.

2. The optical fiber polishing method according to claim 1, characterized in that: The grinding thickness is calculated by the number of peaks, and the steps are: The optical fiber sensor is set up, and the sensor diaphragm is regarded as a solid cavity. The three reflection surfaces form two FP cavities. The incident light is reflected and transmitted to different degrees between the three reflection surfaces. Finally, the reflected light is superimposed and interfered with each other to form a spectrum. The three reflection surfaces are recorded as M1, M2 and M3 respectively. The intensity of the reflected light formed after the interference is expressed as: ; Where: is the output light intensity; , , are the reflectivities at the reflection surfaces M1, M2 and M3 respectively; is the output wavelength; , is the refractive index of the medium of the FP solid cavity and the FP hollow cavity; , are the cavity lengths of the FP solid cavity and the FP hollow cavity, respectively; is the ratio of pi; is the cosine function; The interference signal of the FP solid cavity is: ； In the formula, , are the reflectivities at the reflection surfaces M1 and M2 respectively; is the refractive index of the medium of the FP solid cavity; is the cavity length of the FP solid cavity; is the ratio of pi; is the cosine function; is the output wavelength; Considering the half-wave loss, the initial phase is , when the phase difference When the interference is destructive, the expression for the reduction of the cavity length of the FP solid cavity during the grinding process is: ； In the formula, is the interference order, i.e., the actual number of envelopes generated by the FP sensor during the grinding process; is the refractive index of the medium of the FP solid cavity, ; is the output wavelength; is the reduction in cavity length of the FP solid cavity; is the ratio of pi; The grinding thickness is monitored in real time by the reduction of cavity length.

3. The optical fiber polishing method according to claim 2, characterized in that: The initial grinding point is determined by the change in the length of the FP hollow core cavity after it is pressurized, and the steps are as follows: According to the definition of Young's modulus: ； Where, E is Young's modulus; F is the applied pressure; S is the area of ​​the effective force-bearing cross section; L is the length of the FP hollow cavity; is the change in the length of the FP hollow core cavity; this equation can be transformed into: ； Where, E is Young's modulus; F is the applied pressure; S is the area of ​​the effective force-bearing cross section; L is the length of the FP hollow cavity; is the change in the length of the FP hollow core cavity; When the pressure on the grinding disc (2) changes, the length of the hollow core cavity of the optical fiber sensor FP will also change. When the structural parameters of the optical fiber sensor are determined, E, S, and L in the formula are determined values, and the change in the length of the hollow core cavity FP is proportional to the pressure on the optical fiber. According to the formula ， When the sensor diaphragm contacts the grinding disk (2), after the end of the optical fiber sensor is pressurized, the length of the FP hollow core cavity changes, and the spectral waveform drifts to the right. The pressure value exerted on the end of the optical fiber sensor at this time is obtained through the drift amount of a certain peak of the spectral waveform. When the optical fiber FP sensor reaches a preset pressure value, it is used as the grinding starting point of the optical fiber sensor.

4. The optical fiber polishing method according to claim 3, characterized in that: In the real-time monitoring step of grinding thickness, the signal is processed by a demodulation algorithm, and the steps are as follows: S21, performing fast Fourier transform on the dual FP interference signal to obtain two main peaks, and obtaining the FP hollow-core cavity amplitude-frequency characteristics and the FP solid-cavity amplitude-frequency characteristics after filter separation, performing inverse Fourier transform on the FP solid-cavity amplitude-frequency characteristics to obtain the FP solid-cavity interference spectrum signal, and performing inverse Fourier transform on the FP hollow-core cavity amplitude-frequency characteristics to obtain the FP hollow-core cavity interference spectrum signal; S22. Use the peak-finding algorithm to find the wavelength value corresponding to a peak, and use the formula , then the pressure value on the end of the optical fiber sensor at this time can be obtained by using the drift of the peak of the spectrum waveform; S23, filtering the obtained FP solid cavity interference spectrum signal using a filter to obtain an interference signal at a specific wavelength; S24, during the grinding process, the spectral signal changes due to the reduction of the cavity length of the FP solid cavity, and the spectral signal generated in this process is pre-processed by standardization and normalization to obtain a spectral signal with equal amplitude everywhere, and the spectral signal after pre-processing is denoised to obtain a smooth spectral signal; S25, use the peak-finding algorithm to detect whether an envelope has two peaks, remove the redundant peaks, and obtain the actual envelope number ; S26, through the thickness calculation formula Get the real-time thickness of the film during the grinding process; In the formula, To measure the initial thickness of the FP solid cavity by microscope, is the expression for the reduction of cavity length of FP solid cavity during grinding; is the refractive index of the medium of the FP solid cavity, is the interference order, that is, the actual number of envelopes generated by the FP sensor during the grinding process.

5. The optical fiber polishing method according to claim 1, wherein: The module frame (3) comprises a cylinder (31), a partition (32), a sleeve (33) and a cover plate (34), wherein: The plane (301) and the arc-shaped surface (302) are arranged on the cylinder (31); The partition (32) is arranged in the cylinder (31) to divide the inner cavity of the cylinder (31) into a top cavity (303) and a bottom cavity (304); The sleeve (33) passes through the partition (32), and the clamping assembly (4) is plugged into the sleeve (33); The cover plate (34) is arranged on the cylinder (31) to seal the top cavity (303), and the cover plate (34) is provided with a first notch (305) corresponding to the sleeve (33); The adjusting locking member (5) is arranged in the top cavity (303), and the adjusting end of the adjusting locking member (5) passes through the cover plate (34).

6. The optical fiber polishing method according to claim 5, characterized in that: The clamping assembly (4) comprises a fixing seat (41), an inner tube (42), a bolt (43), a bottom clamp (44), an insert (45) and a top clamp (46), wherein: The fixing seat (41) is inserted into the sleeve (33), and a first opening (4101) is provided on one side of the fixing seat (41); The inner tube (42) is arranged in the fixing seat (41), and the inner tube (42) is provided with a second opening (4201) corresponding to the first opening (4101); The bolt (43) is threadedly connected to the fixing seat (41), and the bolt (43) passes through the fixing seat (41) and abuts against the inner tube (42); The bottom clamp (44) is arranged at the lower end of the inner tube (42), the insert core (45) is arranged inside the bottom clamp (44), the insert core (45) is plugged into the inner tube (42), and a third opening (4501) is arranged corresponding to the second opening (4201); The bottom clamp (44) is used to squeeze the ferrule (45) to clamp a point of the optical fiber sensor; The top clamp (46) is arranged at the upper end of the inner tube (42), and the top clamp (46) is used to clamp a point of the optical fiber sensor and control the feeding of the optical fiber sensor.

7. The optical fiber polishing method according to claim 6, characterized in that: The bottom clamp (44) comprises a cone clamp (441) and a cone sleeve (442), and the insert (45) comprises a continuous plug-in section (451), a transition section (452) and a clamping section (453), wherein: The bottom end of the inner tube (42) is provided with a first conical surface (4202) and a first positioning groove (4203); The plug-in section (451) is plugged into the first positioning groove (4203), the transition section (452) is provided with a second conical surface (4502) continuous with the first conical surface (4202), and the transition section (452) and the clamping section (453) are both located outside the inner tube (42); The cone clamp (441) is sleeved on the insert (45), the top surface of the cone clamp (441) abuts against the first cone surface (4202), and a gap (401) is left between the inner wall of the cone clamp (441) and the transition section (452) and the clamping section (453); A plurality of second notches (4401) are provided on the circumferential surface of the cone clamp (441) to form a plurality of arc plates (4411), wherein one of the arc plates (4411) closes a side surface of the third opening (4501); The cone sleeve (442) is sleeved on the inner tube (42) and the cone clamp (441), and the cone sleeve (442) is connected to the inner tube (42) via threads; When the cone sleeve (442) is tightened, the cone clamp (441) contacts the end of the clamping section (453) away from the inner tube (42).

8. The optical fiber polishing method according to claim 6, wherein: The top clamp (46) comprises a clamp seat (461), a clamp plate (462), a first spring (463), a first clamp roller (464), a second clamp roller (465) and a rotating member (466), wherein: The clamp seat (461) is provided with a second positioning groove (4601), and the clamp seat (461) is provided with a through groove (4602) corresponding to the second opening (4201), so as to divide the clamp seat (461) into a connected fixing plate (4611) and a positioning plate (4612); One end of the inner tube (42) away from the bottom clamp (44) is inserted into the second positioning groove (4601); The positioning plate (4612) is provided with a boss (46121) and a slot (4603), and the middle section of the clamping plate (462) is rotatably connected to the boss (46121); One end of the first spring (463) is inserted into the slot (4603), and the other end abuts against the lower end of the clamping plate (462); the second positioning groove (4601) is provided with a plane portion (46011) corresponding to the slot (4603); The first clamping roller (464) is rotatably disposed on the fixed plate (4611); The second clamping roller (465) is rotatably connected to the clamping plate (462) via the rotating member (466), and the second clamping roller (465) and the rotating member (466) are circumferentially limited relative to each other.

9. The optical fiber polishing method according to claim 5, characterized in that: The adjusting locking member (5) comprises a second spring (51), a rotating shaft (52), a pressure cover (53), a shifting rod (54), a steering gear (55), a limiting rod (56) and a limiting block (57), wherein: The second spring (51) is arranged in the sleeve (33); The rotating shaft (52) is arranged on the partition plate (32); The middle section of the gland (53) is rotatably connected to the rotating shaft (52); The shifting rod (54) is arranged on one end of the pressing cover (53), and the shifting rod (54) passes through the cover plate (34), and the cover plate (34) is provided with an arc-shaped groove (306) corresponding to the shifting rod (54); The steering gear (55) is arranged on the partition (32); the limiting rod (56) is connected to the main shaft of the steering gear (55); The limit block (57) is arranged on the steering gear (55); When the grinding processing device is grinding, the limit block (57) limits the limit rod (56), and the pressure cover (53) closes the top end of the sleeve (33), so that the clamping assembly (4) maintains the grinding height; When the grinding device finishes grinding, the limit rod (56) is in the adjustment position, the pressure cover (53) releases the seal on the sleeve (33), and the second spring (51) pops up the clamping assembly (4) so ​​that the clamping assembly (4) maintains a standby height.

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