A femtosecond laser-based fiber grating automatic processing and sorting system and method

Abstract

The application belongs to the technical field of optical fiber preparation automation, and specifically discloses a femtosecond laser-based optical fiber grating automatic processing and sorting system and method. The system comprises a sorting unit, a processing unit and a detection unit. The sorting unit comprises a feeder for automatically feeding optical fibers during processing, a winding machine connected with the feeder through an optical fiber and used for packaging and winding the finished optical fibers, and an industrial robot used for sorting the packaged finished optical fibers. The processing unit is arranged between the feeder and the winding machine and is used for processing optical fiber gratings. The detection unit comprises a test light source, an optical circulator, an optical spectrum analyzer and a loss module. The optical circulator is connected with the test light source, the optical spectrum analyzer and the optical fiber on the feeder. The loss module is arranged between the processing unit and the winding machine and blocks the propagation of test laser emitted by the test light source in the optical fiber through a bent optical fiber. The control unit is in communication connection with the processing unit, the sorting unit and the detection unit and is used for realizing optical fiber grating automatic processing and sorting.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical fiber preparation automation, and more particularly, relates to a femtosecond laser-based optical fiber grating automated processing and sorting system and method. BACKGROUND

[0002] As a kind of passive optical device with periodic refractive index modulation formed inside the fiber core, the optical fiber grating has been widely used in optical fiber communication, optical fiber laser, and distributed sensing system for structure health monitoring, temperature and strain sensing, etc. due to its advantages of high sensitivity, anti-electromagnetic interference, corrosion resistance and reusability. Especially in long-distance, multi-point measurement scenarios, using wavelength division multiplexing and time division multiplexing technology, only one optical fiber can integrate multiple grating units, which can realize high-precision synchronous sensing of multiple parameters in complex environments. At present, the main long-distance distributed optical fiber grating manufacturing processes in China mainly include ultraviolet mask exposure method and femtosecond laser direct writing method. Among them, the ultraviolet mask exposure method uses ultraviolet laser to cooperate with a phase mask to perform periodic exposure on the fiber after drawing and forming, and then completes the grating production by coating a protective layer. This method has mature technology and good consistency, but the refractive index modulation structure formed is non-permanent and is easily affected by high temperature or long-term use, which limits its application in high temperature or harsh environments. In comparison, the femtosecond laser processing technology can induce stable and permanent refractive index changes in the fiber due to the nonlinear absorption effect of ultrashort pulses, thereby realizing the preparation of high-temperature stable optical fiber gratings and having a broader application prospect.

[0003] In view of the production needs of femtosecond laser processing of optical fiber gratings, the prior art has made preliminary exploration. In the processing positioning and packaging link, the existing scheme mainly relies on manual cooperation with basic mechanical conveying devices, determines the grating processing position by manual observation and performs dot marking, manually inspects each section after processing is completed, and then manually cuts and packages into a roll; in the processing process monitoring link, some devices try to use a spectrum detection module to detect the whole processed optical fiber offline, and judge the grating quality by comparing the standard spectrum; in the aspect of automatic control, the existing devices can only realize the basic linkage of femtosecond laser emission and optical fiber transmission, and have not formed a full-process closed-loop control. In addition, in order to improve the monitoring pertinence, some researches propose to add an optical detection unit beside the processing device to try to observe the processing area in real time.

[0004] Therefore, the prior art still has several key defects, which seriously restrict the industrialization process of femtosecond laser processing fiber grating. For example, in the whole processing flow, the positioning, dot marking, quality detection and volume packaging of the grating still highly depend on manual operation, which not only consumes time and effort, but also easily introduces human error, significantly increases the manufacturing cost and reduces the overall production efficiency; secondly, in the continuous dynamic processing process, there is a lack of real-time online monitoring capability for the newly completed grating unit, which cannot effectively shield the crosstalk of the previously processed grating to the current detection signal, making it difficult to accurately evaluate the actual performance of a single grating, thereby affecting the product consistency control; thirdly, the existing equipment generally uses an offline method to obtain the reflection spectrum, which cannot identify and classify the key parameters such as the center wavelength, reflectivity and bandwidth of each grating in real time while processing, resulting in the mixing of high-quality gratings and unqualified products, making it difficult to achieve efficient automatic sorting; in addition, manual intervention is still required for cutting and winding after processing, further lengthening the production cycle and limiting the continuous and intelligent level of the production line. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a femtosecond laser-based automatic processing and sorting system and method for fiber gratings, which integrates a processing unit, a sorting unit, a detection unit and a control unit, significantly improving the intelligentization and industrialization level of fiber grating manufacturing, thereby effectively solving the problem of relying on manual positioning, quality inspection and packaging in the prior art, and overcoming the technical bottleneck of being unable to monitor and shield the interference of previous fiber gratings in the dynamic processing process, thereby providing reliable technical support for large-scale and low-cost production of high-performance and high-consistency fiber gratings.

[0006] To achieve the above-mentioned purpose, the present application provides a femtosecond laser-based automatic processing and sorting system for fiber gratings, comprising: a processing unit, a sorting unit, a detection unit and a control unit; wherein:

[0007] The sorting unit comprises: a feeder for automatically feeding the fiber during processing, a winding machine connected with the feeder through an optical fiber and used for packaging the finished fiber products, and an industrial robot for sorting the packaged fiber products;

[0008] The processing unit is arranged between the feeder and the winding machine, and is used for grating processing of the fiber, and comprises: a femtosecond laser source for emitting femtosecond laser, a three-axis motion module for ensuring that the femtosecond laser is always focused on the core center, an imaging lens and an imaging camera for obtaining a clear fiber image;

[0009] The detection unit comprises a test light source, a circulator, a spectrometer and a loss module; the circulator is connected with the test light source, the spectrometer and the optical fiber on the feeder at the same time; the loss module is arranged between the processing unit and the winding machine, and the propagation of the test laser emitted by the test light source in the optical fiber is blocked by bending the optical fiber;

[0010] The sorting unit further comprises a length encoder, a code printer and a cutting machine; the length encoder, the code printer and the cutting machine are sequentially arranged between the loss module and the winding machine;

[0011] The control unit is in communication connection with the processing unit, the sorting unit and the detection unit, and is used for realizing automatic processing and sorting of the fiber grating.

[0012] Further, the sorting unit further comprises a tension sensor; the tension sensor is arranged between the processing unit and the loss module, and is used for cooperating with the feeder to realize real-time monitoring and dynamic adjustment of the tension state of the optical fiber in the processing and transmission process.

[0013] Further, the sorting unit further comprises a classification basket, and the classification basket is at least two and is arranged on one side of the industrial robot arm.

[0014] Further, the processing unit comprises a laser beam expander, a laser power regulator, a reflector, a dichroic mirror, a microscope objective, a white light source and an optical fiber holder;

[0015] The laser emitted by the femtosecond laser source sequentially passes through the laser beam expander, the laser power regulator, the reflector, the dichroic mirror and the microscope objective on the optical path, and irradiates the optical fiber on the optical fiber holder;

[0016] The white light source is arranged on the optical fiber holder and below the optical fiber, the light emitted by the white light source is reflected to the imaging lens through the dichroic mirror, and focused into the imaging camera.

[0017] Further, the three-axis motion module comprises an X-axis motion sub-module, a Y-axis motion sub-module and a Z-axis motion sub-module;

[0018] The X-axis motion sub-module and the Y-axis motion sub-module are movably connected, and are used for adjusting the horizontal position of the optical fiber holder;

[0019] The Z-axis motion sub-module is fixedly provided with the dichroic mirror, the microscope objective, the imaging lens and the imaging camera, and is used for dynamically adjusting the distance between the microscope objective and the optical fiber.

[0020] The second aspect of the application provides a femtosecond laser-based fiber grating automatic processing sorting method, which is implemented by using the automatic processing sorting system described above and includes the following steps:

[0021] S1: the fiber is sequentially inserted into the fiber holder, the tension sensor, the loss module, the length encoder, the inkjet printer, the cutting machine and the winding machine through the feeder, the first fiber insertion before grating processing is completed, and one end of the fiber is connected with the circulator;

[0022] S2: the horizontal position of the fiber and the vertical position of the processing unit components are adjusted by the three-axis motion module, so that the fiber core in the processing area can be clearly displayed in the imaging camera;

[0023] S3: the moving speed of the fiber is adjusted by the three-axis motion module, the feeder and the winding machine, at the same time, the switch of the femtosecond laser light source is controlled to make the laser on the fiber to be processed, and the processing of a section of fiber grating is completed;

[0024] S4: the fiber passing through the loss module is shielded, at the same time, the parameter detection of the fiber grating processed in step S3 is detected by the test light source, then the related data is sent to the control unit by the spectrometer, and whether the current fiber grating is qualified is judged;

[0025] S5: after the parameter detection is completed, the feeder and the winding machine are cooperated and synchronized to carry out the feeding and packaging of the fiber, at the same time, the cutting machine cuts the fiber product on the winding machine;

[0026] S6: according to the detection result of the fiber product, the industrial robot places the fiber product on the winding machine into the corresponding classification basket;

[0027] S7: the processing work of the current batch of fiber is completed by repeating steps S2 to S6.

[0028] Further, in step S2, before the processing of the fiber grating, the feeder and the winding machine are cooperated to control the fiber to move forward to the winding machine side by a set length.

[0029] Further, in step S3, before the processing of the fiber grating, according to the length L of the fiber to be processed and the fiber core position focused by the imaging camera, the fiber is controlled to move reversely to the feeder side by L / 2 length, the newly obtained fiber core position is recorded as the starting endpoint, then the fiber is moved forward to the winding machine side by L length from the starting endpoint, the newly obtained fiber core position is recorded as the ending endpoint, so as to obtain the movement trajectory of the fiber to be processed during grating processing, and the fiber segment from the starting endpoint to the ending endpoint is the irradiation area of the femtosecond laser light source.

[0030] Further, in step S4, according to the fiber grating length, the feeder 11 and the winding machine 20 cooperatively control the fiber to advance a certain distance, for controlling the position of the fiber bent by the loss module 17.

[0031] The third aspect of the present application provides a computer readable storage medium, which comprises a stored computer program, and the computer program controls a device where the storage medium is located to execute the automatic processing sorting method as described above when the computer program is run by a processor.

[0032] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0033] 1. The automatic processing sorting system of the present application significantly improves the intelligentization and industrialization level of fiber grating manufacturing by integrating processing units, sorting units, detection units and control units, thereby effectively solving the problem of relying on manual positioning, quality inspection and packaging in the prior art, and overcoming the technical bottleneck that the previous fiber grating cannot be monitored in real time and shielded from interference in the dynamic processing process, thereby providing reliable technical support for large-scale, low-cost production of high-performance, high-consistency fiber gratings.

[0034] 2. The automatic processing sorting system of the present application highly integrates precision motion control and optical systems, not only realizes three-dimensional accurate positioning of the fiber position in the processing process, but also supports closed-loop correction under real-time visual guidance, effectively overcoming the processing deviation caused by mechanical vibration, thermal drift or fiber deformation; thus, the system can complete continuous automatic writing of complex arrangement or multi-section gratings without human intervention, greatly improving processing efficiency, consistency and yield, and providing a key equipment foundation for large-scale intelligent manufacturing of high-performance fiber gratings.

[0035] 3. The automatic processing sorting system of the present application organically integrates tension closed-loop control, length accurate measurement, automatic information marking and intelligent cutting, which can greatly reduce labor costs and the risk of misoperation, and significantly improve sorting efficiency, product consistency and quality control ability. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 FIG. 1 is a structural schematic diagram of an automatic processing sorting system according to an embodiment of the present application;

[0037] Figure 2 FIG. 4 is a structural schematic diagram of a control unit according to an embodiment of the present application;

[0038] Figure 3 FIG. 6 is a step flowchart of an automatic processing sorting method according to an embodiment of the present application.

[0039] In all the drawings, the same reference signs represent the same technical features, specifically: 1 - femtosecond laser light source, 2 - laser beam expander, 3 - laser power regulator, 4 - mirror, 5 - dichroic mirror, 6 - microscope objective, 7 - imaging lens, 8 - imaging camera, 9 - white light source, 10 - three-axis motion module, 11 - feeder, 12 - fiber holder, 13 - test light source, 14 - circulator, 15 - optical spectrum analyzer, 16 - tension sensor, 17 - loss module, 18 - length encoder, 19 - inkjet printer, 20 - winding machine, 21 - cutting machine, 22 - industrial robot, 23 - sorting basket, 24 - processor, 25 - communication bus, 26 - user interface, 27 - network interface, 28 - memory. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0041] Embodiment 1, please refer to Figure 1 and Figure 2 The present application provides a femtosecond laser-based fiber grating automatic processing and sorting system, which comprises a processing unit, a sorting unit, a detection unit and a control unit; wherein:

[0042] The sorting unit comprises a feeder 11 for automatically feeding the fiber during processing, a winding machine 20 connected to the feeder 11 by an optical fiber and used for packaging the finished fiber into a roll, and an industrial robot 22 for sorting the packaged finished fiber;

[0043] The processing unit is arranged between the feeder 11 and the winding machine 20, and is used for grating processing of the fiber, which comprises a femtosecond laser light source 1 for emitting femtosecond laser, a three-axis motion module 10 for ensuring that the femtosecond laser is always focused on the core center, an imaging lens 7 and an imaging camera 8 for obtaining a clear fiber image;

[0044] The detection unit comprises a test light source 13, a circulator 14, an optical spectrum analyzer 15 and a loss module 17; the circulator 14 is connected to the test light source 13, the optical spectrum analyzer 15 and the fiber on the feeder 11 at the same time; the loss module 17 is arranged between the processing unit and the winding machine 20, and blocks the propagation of the test laser emitted by the test light source 13 in the fiber by bending the fiber;

[0045] The sorting unit further comprises a length counter encoder 18, a code printer 19 and a cutting machine 21, which are sequentially arranged between the loss module 17 and the winding machine 20.

[0046] The control unit is in communication connection with the processing unit, the sorting unit and the detection unit, and is used for realizing automatic processing and sorting of fiber gratings.

[0047] It can be understood that, in the production process of fiber gratings, the sorting unit comprises the feeder 11, the winding machine 20 and the industrial robot arm 22, realizing the whole-process unmanned operation from automatic fiber feeding, finished product winding to intelligent sorting, greatly reducing the manual intervention and time cost; the processing unit is arranged between the feeder 11 and the winding machine 20, ensuring that the fiber is efficiently completed in the continuous feeding process. The detection unit is composed of the test light source 13, the circulator 14, the spectrometer 15 and the loss module 17, wherein the circulator 14 guides the test laser emitted by the test light source 13 into the fiber to be tested, and guides the reflected light to the spectrometer 15 for real-time spectral analysis, and the loss module 17 is arranged between the processing unit and the winding machine 20, and the completed grating blocks the subsequent detection signal through controllable bending, thereby ensuring the accurate identification of the performance parameters (such as center wavelength, bandwidth, side mode suppression ratio, reflection intensity, etc.) of a single grating; the control unit is in communication connection with the above-mentioned units, and coordinates the processing, detection and sorting actions, realizes the online quality evaluation and automatic classification of each fiber grating. In addition, in the production process of fiber gratings, the length counter encoder 18 can accurately record the length of the processed fiber, providing high-precision data support for subsequent segmentation according to the preset grating pitch or product specification; the code printer 19 automatically prints a unique identification code on the surface of the detected qualified fiber according to the instruction of the control unit, which contains key information such as grating center wavelength, production batch, position serial number, etc., realizing the traceability management of the whole life cycle of the product; the cutting machine 21 cuts the different grades of fiber products automatically wound and stored on the winding machine 20 according to the length signal fed back by the length counter encoder 18 and the quality judgment result of the detection unit.

[0048] It should be noted that, by arranging the cutting machine 21 at the front end of the winding machine 20, and also packaging the unqualified products or fiber segments with length deviation (overlength / shortage), the industrial robot arm 22 uniformly performs the sorting operation, effectively ensuring the continuity and automation level of the production line process. This method can avoid interrupting the winding operation due to the removal of abnormal segments, and improve the equipment operation efficiency; at the same time, by uniformly winding and then classifying and putting them into the corresponding classification basket 23 according to the detection result by the industrial robot arm 22, the consistency of the sorting logic and the reliability of the operation are ensured, so as to simplify the complexity of the control system, enhance the product quality traceability ability, and significantly improve the stability and intelligent degree of the whole production system.

[0049] Specifically, the processing unit comprises a laser beam expander 2, a laser power regulator 3, a mirror 4, a dichroic mirror 5, a microscope objective 6, a white light source 9 and a fiber holder 12; the laser emitted by the femtosecond laser source 1 passes through the laser beam expander 2, the laser power regulator 3, the mirror 4, the dichroic mirror 5 and the microscope objective 6 in sequence, and irradiates the optical fiber on the fiber holder 12; the white light source 9 is arranged on the fiber holder 12 and below the optical fiber, and the light emitted by the white light source 9 is reflected by the dichroic mirror 5 to the imaging lens 7 and focused into the imaging camera 8. It can be understood that, by the above design, the precision, stability and automation level of the femtosecond laser writing optical fiber grating are significantly improved by using precise optical path design and cooperation of multiple components.

[0050] It should be noted that, please refer to Figure 1 In the embodiment, the femtosecond laser source 1 is a laser (Light Amplification by Stimulated Emission of Radiation, LASER) with a pulse duration in the order of femtosecond; the imaging camera 8 converts the incident photons into corresponding number of charges based on the internal charge-coupled device (Charge-Coupled Device, CCD), completes photoelectric conversion, and sequentially couples and sequentially transmits these charge packets to the output end, and finally collects into a complete image electrical signal; the test light source 13 is a wide-spectrum, incoherent “laser-like” light source based on ASE (Amplified Spontaneous Emission), and when it is necessary to test the response characteristics of the optical fiber amplifier, filter and other devices at different wavelengths, it can provide an output with a wide wavelength range and high power, thereby avoiding the tedious repeated scanning of a single wavelength laser, greatly improving the test efficiency, and in other embodiments, other types of light sources and image transmission can also be adopted, as long as they can output the required laser and obtain accurate images, which is not limited here.

[0051] Further, the three-axis movement module 10 comprises an X-axis movement sub-module, a Y-axis movement sub-module, and a Z-axis movement sub-module; the X-axis movement sub-module is movably connected with the Y-axis movement sub-module, for adjusting the horizontal position of the optical fiber holder 12; the Z-axis movement sub-module is fixed with the dichroic mirror 5, the microscope objective 6, the imaging lens 7, and the imaging camera 8, for dynamically adjusting the distance between the microscope objective 6 and the optical fiber. It can be understood that, by adjusting the lifting of the Z-axis movement sub-module, the automatic focusing of optical fibers with different diameters or coating layer thicknesses is realized, so that the femtosecond laser is always focused on the core center, and the precision and stability of the refractive index modulation are improved; at the same time, the imaging lens 7 and the imaging camera 8 move synchronously with the Z-axis, so that clear optical fiber images can be obtained at different focal planes, and reliable data support is provided for visual feedback control.

[0052] Further, the sorting unit further comprises a tension sensor 16; the tension sensor 16 is arranged between the processing unit and the loss module 17, for cooperating with the feeder 11 to monitor and dynamically adjust the tension state of the optical fiber in the processing and transmission process in real time, so as to effectively avoid the grating period distortion or core damage caused by tension fluctuation, thereby ensuring the consistency of the grating structure and the stability of the optical performance.

[0053] In an optional embodiment, the sorting unit further comprises classification baskets 23, the classification baskets 23 are at least two and are arranged on one side of the industrial robot arm 22, different grades of optical fiber products can be automatically classified and stored in the corresponding classification baskets 23 by the industrial robot arm 22 according to the real-time quality determination result of the detection unit, so that efficient and accurate grading management is realized, and the product sorting efficiency and quality traceability are significantly improved. It should be noted that, please refer to Figure 1 In this embodiment, the optical fiber products are classified and placed in the corresponding classification baskets 23, wherein the qualified products are placed in the classification baskets 23 marked with “✔”, and the unqualified products are placed in the classification baskets 23 marked with “✘”, so as to avoid confusion.

[0054] Further, the control unit comprises: a processor 24, a communication bus 25, a user interface 26, a network interface 27 and a memory 28; wherein the communication bus 25 is at least one quantity, used to realize the connection communication between these components; the user interface 26 can include a display (Display), a keyboard (Keyboard), and the optional user interface 26 can also include a standard wired interface, a wireless interface. The network interface 27 can optionally include a standard wired interface, a wireless interface (such as a WI-FI interface). The memory 28 can be a high-speed RAM memory, or a non-volatile memory, such as at least one disk memory. The memory 28 can also be at least one storage device located away from the aforementioned processor 24. As shown in Figure 3 the memory 28 as a kind of computer readable storage medium can include operating system, network communication module, user interface module and device control application program. The network interface 27 can provide network communication function; and the user interface 26 is mainly used to provide the interface for user input; and the processor 24 can be used to call the device control application program stored in the memory 28.

[0055] It should be understood that in some possible implementations, the aforementioned processor 24 can be a central processing unit (CPU), and the processor can also be other general-purpose processors, DSPs, ASICs, FPGAs or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor. The memory can include read-only memory and random access memory, and provide instructions and data for the processor. Part of the memory can also include non-volatile random access memory. For example, the memory can also store device type information.

[0056] In an optional embodiment, the control unit is communicatively connected with the femtosecond laser source 1, the laser beam expander 2, the laser power regulator 3, the imaging camera 8, the three-axis motion module 10, the feeder 11, the fiber holder 12, the test light source 13, the spectrometer 15, the tension sensor 16, the length encoder 18, the inkjet printer 19, the winding machine 20, the cutting machine 21 and the industrial robot 22, for realizing highly integrated and closed-loop control of the whole process from grating writing, online detection to post-processing sorting. It can be understood that through the unified control architecture, the system can dynamically coordinate each functional module according to the preset process parameters or real-time feedback data: for example, the three-axis motion module 10 is adjusted according to the visual information of the imaging camera 8 to realize accurate focusing, and the tension sensor 16 is combined with the feeder 11 and the winding machine 20 to maintain constant tension; during the processing, the femtosecond laser source 1, the laser beam expander 2 and the laser power regulator 3 are triggered synchronously to ensure stable energy; after processing, the test light source 13 and the spectrometer 15 cooperate to complete the acquisition of the reflected spectrum, and the control unit determines the quality of the grating accordingly, and instructs the inkjet printer 19 to selectively mark the qualified products; then, the length encoder 18 provides a length reference to drive the cutting machine 21 to accurately cut off, and the winding machine 20 completes the winding, and finally the industrial robot 22 sorts the finished products into corresponding sorting baskets 23 according to the inkjet information. In summary, through the highly coordinated control system, not only the manual intervention is completely eliminated, the production efficiency and product consistency are significantly improved, but also the process traceability and system robustness are enhanced, providing a solid technical support for large-scale, intelligent and high-quality manufacturing of femtosecond laser direct writing fiber grating.

[0057] In an optional embodiment, the control unit is communicatively connected with the femtosecond laser source 1, the laser beam expander 2, the laser power regulator 3, the imaging camera 8, the three-axis motion module 10, the feeder 11, the fiber holder 12, the test light source 13, the spectrometer 15, the tension sensor 16, the length encoder 18, the inkjet printer 19, the winding machine 20, the cutting machine 21 and the industrial robot 22, for realizing highly integrated and closed-loop control of the whole process from grating writing, online detection to post-processing sorting. It can be understood that through the unified control architecture, the system can dynamically coordinate each functional module according to the preset process parameters or real-time feedback data: for example, the three-axis motion module 10 is adjusted according to the visual information of the imaging camera 8 to realize accurate focusing, and the tension sensor 16 is combined with the feeder 11 and the winding machine 20 to maintain constant tension; during the processing, the femtosecond laser source 1, the laser beam expander 2 and the laser power regulator 3 are triggered synchronously to ensure stable energy; after processing, the test light source 13 and the spectrometer 15 cooperate to complete the acquisition of the reflected spectrum, and the control unit determines the quality of the grating accordingly, and instructs the inkjet printer 19 to selectively mark the qualified products; then, the length encoder 18 provides a length reference to drive the cutting machine 21 to accurately cut off, and the winding machine 20 completes the winding, and finally the industrial robot 22 sorts the finished products into corresponding sorting baskets 23 according to the inkjet information. In summary, through the highly coordinated control system, not only the manual intervention is completely eliminated, the production efficiency and product consistency are significantly improved, but also the process traceability and system robustness are enhanced, providing a solid technical support for large-scale, intelligent and high-quality manufacturing of femtosecond laser direct writing fiber grating. Figure 3 In an optional embodiment, the control unit is communicatively connected with the femtosecond laser source 1, the laser beam expander 2, the laser power regulator 3, the imaging camera 8, the three-axis motion module 10, the feeder 11, the fiber holder 12, the test light source 13, the spectrometer 15, the tension sensor 16, the length encoder 18, the inkjet printer 19, the winding machine 20, the cutting machine 21 and the industrial robot 22, for realizing highly integrated and closed-loop control of the whole process from grating writing, online detection to post-processing sorting. It can be understood that through the unified control architecture, the system can dynamically coordinate each functional module according to the preset process parameters or real-time feedback data: for example, the three-axis motion module 10 is adjusted according to the visual information of the imaging camera 8 to realize accurate focusing, and the tension sensor 16 is combined with the feeder 11 and the winding machine 20 to maintain constant tension; during the processing, the femtosecond laser source 1, the laser beam expander 2 and the laser power regulator 3 are triggered synchronously to ensure stable energy; after processing, the test light source 13 and the spectrometer 15 cooperate to complete the acquisition of the reflected spectrum, and the control unit determines the quality of the grating accordingly, and instructs the inkjet printer 19 to selectively mark the qualified products; then, the length encoder 18 provides a length reference to drive the cutting machine 21 to accurately cut off, and the winding machine 20 completes the winding, and finally the industrial robot 22 sorts the finished products into corresponding sorting baskets 23 according to the inkjet information. In summary, through the highly coordinated control system, not only the manual intervention is completely eliminated, the production efficiency and product consistency are significantly improved, but also the process traceability and system robustness are enhanced, providing a solid technical support for large-scale, intelligent and high-quality manufacturing of femtosecond laser direct writing fiber grating.

[0058] S1: The fiber is sequentially threaded through the fiber holder 12, the tension sensor 16, the loss module 17, the length encoder 18, the inkjet printer 19, the cutting machine 21 and the winding machine 20 via the feeder 11, completing the first fiber threading before grating processing, and connecting one end of the fiber with the circulator 14;

[0059] S2: Adjust the horizontal position of the fiber and the vertical position of the processing unit components through the three-axis motion module 10, so that the fiber core in the processing area can be clearly displayed in the imaging camera 8;

[0060] S3: Adjust the fiber movement speed through the three-axis motion module 10, the feeder 11 and the winding machine 20, and at the same time, control the femtosecond laser source 1 to switch on and off to make the laser hit the processing area of the fiber, completing the processing of a section of fiber grating;

[0061] S4: shielding the optical fiber passing through the loss module 17, while the test light source 13 is turned on to detect the parameters of the fiber grating processed in step S3, then the spectrometer 15 sends the relevant data to the control unit, and judges whether the current fiber grating is qualified;

[0062] S5: after completing the parameter detection, the feeder 11 and the winding machine 20 cooperatively and synchronously perform the feeding and packaging of the optical fiber; meanwhile, the cutting machine 21 cuts the optical fiber product on the winding machine 20;

[0063] S6: according to the detection result of the optical fiber product, the industrial robot 22 places the optical fiber product on the winding machine 20 into the corresponding classification basket 23;

[0064] S7: repeat steps S2 to S6 to complete the processing work of the current batch of optical fiber.

[0065] In an optional embodiment, in step S2, before processing the fiber grating, the feeder 11 and the winding machine 20 cooperatively control the optical fiber to move forward to the side of the winding machine 20 by a set length, which is used to provide stable initial conditions for subsequent grating writing by precise length pre-feeding, and effectively avoid period error or writing failure caused by optical fiber position deviation; at the same time, the synchronous tension control of the feeder 11 and the winding machine 20 helps to maintain the flatness and tension of the optical fiber in the processing area, preventing the adverse effects of micro-bending or relaxation on the grating performance; in addition, this pre-positioning mechanism lays the foundation for the ordered arrangement of multi-section gratings and the length calibration of the subsequent length encoder 18, significantly improving the processing consistency, system repeatability and overall automation level.

[0066] In an optional embodiment, in step S3, before the processing of the fiber grating, according to the length L of the fiber grating to be processed and the current core position focused by the imaging camera 8, the fiber is controlled to move reversely by L / 2 to the side of the feeder, and the newly obtained core position is recorded as the starting endpoint; then, the fiber is controlled to move forward by L to the side of the winding machine 20, and the newly obtained core position is recorded as the ending endpoint, so as to obtain the movement trajectory of the fiber to be processed during the grating processing, and the fiber segment from the starting endpoint to the ending endpoint is the irradiation area of the laser of the femtosecond laser source 1. It can be understood that, by the above design, the real-time visual feedback provided by the imaging camera 8 is fully utilized, combined with high-resolution motion control, to realize closed-loop calibration of the grating position, effectively avoiding problems such as grating misplacement, overlap or loss caused by initial positioning deviation, mechanical transmission error or fiber micro-displacement; at the same time, the clear start and end boundaries provide accurate basis for the trigger timing of the femtosecond laser source 1, the scanning path of the three-axis motion module 10 and the length verification of the length encoder 18, ensuring that each grating is strictly written according to the design parameters; in addition, the trajectory definition mechanism supports flexible arrangement of multi-segment, non-uniform or variable-period gratings, greatly enhancing the process adaptability and intelligent level of the system. In summary, the positioning and trajectory generation method not only guarantees the geometric consistency and optical performance stability of a single grating, but also lays a key technical foundation for the fully automatic manufacturing of high-density and high-precision fiber grating strings.

[0067] In an optional embodiment, in step S3, the fiber movement speed is obtained according to the grating period of the fiber grating to be processed and the laser repetition frequency of the femtosecond laser source 1, and the movement speed value is the product of the grating period and the laser repetition frequency.

[0068] In an optional embodiment, in step S4, according to the length of the fiber grating, the feeder 11 and the winding machine 20 are cooperatively controlled to advance the fiber by a certain distance, for controlling the position of the loss module 17 to bend the fiber. It can be understood that there is a certain distance between the processing position and the loss module 17, and the distance is usually 0.8-1 m. When the total length of the fiber grating is small, there may be a previous grating between the processing position and the loss module 17, for example, the distance between the processing position and the loss module 17 is 0.8 m, and the finished product length of the fiber grating is 0.5 m (the fiber grating is 5 mm, and the distance between the fiber grating and the two ends of the fiber is 250 mm each). In this case, if the fiber is not controlled to advance by a certain distance, the signal of the previous fiber grating will not be shielded when the current fiber grating is tested, and the reflection spectrum collected by the spectrometer 15 contains multiple superimposed signals, which seriously affects the accurate identification of the key parameters such as the center wavelength and reflectivity of the current grating.

[0069] It should be noted that in step S4, the loss module 17 shields the optical fiber passing through it, which means shielding the optical fiber optical path after the loss module 17, not only the pre-sequence grating, so as to perform performance testing in subsequent steps.

[0070] In an optional embodiment, in step S5, if the parameters of the fiber grating are qualified, the inkjet printer 19 sprays marks on the surface of the optical fiber; if the parameters of the fiber grating are not qualified, the inkjet printer 19 does not perform inkjet processing on the optical fiber, thereby realizing intuitive differentiation of qualified products and unqualified products, facilitating subsequent precise sorting by the industrial robot 22 and quality tracing, and improving sorting efficiency and product consistency.

[0071] In embodiment 3, the application also provides a computer readable storage medium storing a computer program, which is executed by a processor to implement each step of the above-mentioned embodiment of the femtosecond laser-based automatic processing and sorting method of fiber gratings, and specific implementation manners are provided in each step, which will not be repeated here.

[0072] It should be understood that although each step in the flowchart of the accompanying drawings is displayed in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and they can be executed in other orders. Moreover, at least part of the steps in the flowchart of the accompanying drawings can include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence is not necessarily sequential, but can be alternately executed with other steps or sub-steps or stages of other steps.

[0073] It should be noted that if the present application involves directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the accompanying drawings), and if the certain posture changes, the directional indications will also change accordingly.

[0074] In addition, if the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0075] In the present application, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or further includes elements inherent to such process, method, article or apparatus. Without more limitations, the elements defined by the statement "comprising" do not exclude the presence of other identical elements in the process, method, article or apparatus including the elements.

[0076] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit it; those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A femtosecond laser based fiber grating automated processing sorting system, characterized in that, The application relates to a fiber grating automatic processing and sorting system. The system comprises a processing unit, a sorting unit, a detection unit and a control unit. The sorting unit comprises a feeder (11) for automatically feeding fibers during processing, a winding machine (20) connected with the feeder (11) through an optical fiber and used for winding the optical fiber products, and an industrial robot (22) used for sorting the packaged optical fiber products. The processing unit is arranged between the feeder (11) and the winding machine (20) and is used for processing the optical fiber, and comprises a femtosecond laser light source (1) for emitting femtosecond laser, a three-axis motion module (10) for ensuring that the femtosecond laser is always focused on the fiber core center, an imaging lens (7) and an imaging camera (8) for obtaining a clear optical fiber image. The detection unit comprises a test light source (13), a circulator (14), a spectrometer (15) and a loss module (17); the circulator (14) is connected with the test light source (13), the spectrometer (15) and the optical fiber on the feeder (11) at the same time; the loss module (17) is arranged between the processing unit and the winding machine (20) and blocks the propagation of the test laser emitted by the test light source (13) in the optical fiber through the bending of the optical fiber; the control unit is configured to control the feeder (11) and the winding machine (20) to cooperatively control the forward movement of the optical fiber by a set distance to position the optical fiber at the loss module (17) for bending, so as to shield the signal of the previously processed fiber grating, when detecting the current processed fiber grating according to the length of the fiber grating to be processed. The sorting unit further comprises a length encoder (18), a code printer (19) and a cutting machine (21); the length encoder (18), the code printer (19) and the cutting machine (21) are sequentially arranged between the loss module (17) and the winding machine (20). The control unit is in communication connection with the processing unit, the sorting unit and the detection unit, and is used for realizing the automatic processing and sorting of the fiber grating.

2. The automated processing sorting system of claim 1, wherein, The sorting unit further comprises a tension sensor (16); the tension sensor (16) is arranged between the processing unit and the loss module (17) and is used for cooperatively working with the feeder (11) to realize the real-time monitoring and dynamic adjustment of the tension state of the optical fiber in the processing and transmission process.

3. The automated processing sorting system of claim 2, wherein, The sorting unit further comprises classification baskets (23); the classification baskets (23) are at least two and are arranged on one side of the industrial robot (22).

4. The automated processing sorting system of any of claims 1-3, wherein, The processing unit comprises a laser expander (2), a laser power regulator (3), a reflecting mirror (4), a dichroic mirror (5), a microscopic objective lens (6), a white light source (9) and an optical fiber holder (12). The laser emitted by the femtosecond laser light source (1) sequentially passes through the laser expander (2), the laser power regulator (3), the reflecting mirror (4), the dichroic mirror (5) and the microscopic objective lens (6) on the light path and irradiates the optical fiber on the optical fiber holder (12). The white light source (9) is arranged on the optical fiber holder (12) and below the optical fiber, and the light emitted by the white light source is reflected by the dichroic mirror (5) to the imaging lens (7) and focused into the imaging camera (8).

5. The automated processing sorting system of claim 4, wherein, The three-axis motion module (10) comprises an X-axis motion sub-module, a Y-axis motion sub-module and a Z-axis motion sub-module. The X-axis motion sub-module and the Y-axis motion sub-module are movably connected, and are used for adjusting the horizontal position of the optical fiber holder (12). The Z-axis motion sub-module is fixedly provided with the dichroic mirror (5), the microscope objective (6), the imaging lens (7) and the imaging camera (8), and is used for dynamically adjusting the distance between the microscope objective (6) and the optical fiber.

6. A femtosecond laser based optical fiber grating automated processing sorting method, implemented by using the automated processing sorting system according to any one of claims 1-5, characterized in that, The method comprises the following steps: S1: the optical fiber is sequentially inserted into the optical fiber holder (12), the tension sensor (16), the loss module (17), the length encoder (18), the inkjet printer (19), the cutting machine (21) and the winding machine (20) through the feeder (11), and the first fiber insertion before grating processing is completed, and one end of the optical fiber is connected with the circulator (14); S2: the horizontal position of the optical fiber and the vertical position of the processing unit component are adjusted by the three-axis motion module (10), so that the optical fiber core in the processing area can be clearly displayed in the imaging camera (8); S3: the three-axis motion module (10), the feeder (11) and the winding machine (20) are cooperatively adjusted to adjust the moving speed of the optical fiber, and at the same time, the on-off of the femtosecond laser light source (1) is controlled to make the laser on the optical fiber processing area, and the processing of a section of optical fiber grating is completed; S4: the loss module (17) shields the optical fiber passing through it, and at the same time, the test light source (13) is turned on to detect the parameters of the optical fiber grating processed in step S3, then the spectrometer (15) sends the related data to the control unit, and judges whether the current optical fiber grating is qualified; S5: after the parameter detection is completed, the feeder (11) and the winding machine (20) cooperatively and synchronously perform the feeding and packaging of the optical fiber, and at the same time, the cutting machine (21) cuts the optical fiber product on the winding machine (20); S6: according to the detection result of the optical fiber product, the industrial robot arm (22) places the optical fiber product on the winding machine (20) in the corresponding classification basket (23); S7: repeat steps S2 to S6 to complete the processing work of the current batch of optical fiber.

7. The automated processing sorting method of claim 6, wherein, In step S2, before the processing of the optical fiber grating, the feeder (11) and the winding machine (20) cooperatively control the optical fiber to move forward to the side of the winding machine (20) by a set length.

8. The automated processing sorting method of claim 6, wherein, In step S3, before the fiber Bragg grating is processed, according to the length L of the fiber Bragg grating to be processed and the current fiber core position focused by the imaging camera (8), the fiber is controlled to move reversely by L / 2 to the side of the feeder, the newly obtained fiber core position is recorded as the starting endpoint; then, the fiber is controlled to move forward by L to the side of the winder (20) with the starting endpoint as the starting point, the newly obtained fiber core position is recorded as the ending endpoint, so as to obtain the movement track of the fiber to be processed during the grating processing, and the fiber segment from the starting endpoint to the ending endpoint is the irradiation area of the femtosecond laser source (1).

9. The automated processing sorting method of claim 6, wherein, In step S4, according to the length of the fiber Bragg grating, the feeder (11) and the winder (20) are cooperatively controlled to advance the fiber by a certain distance, for controlling the position of the loss module (17) to bend the fiber.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium comprises a stored computer program, and the computer program controls the device where the storage medium is located to execute the automatic processing and sorting method according to any one of claims 6 to 9 when the computer program is run by a processor.

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