A three-dimensional focusing lens and a fiber grating writing method based on the lens

Abstract

The present invention relates to the field of optical technology, and in particular to a three-dimensional focusing lens and a fiber grating engraving method based on the lens, wherein a lens group, an image acquisition module, a beam expander, a toe plate, and a cylindrical mirror are integrated in the lens, wherein: the beam expander, the toe plate, and the cylindrical mirror are respectively embedded in the first position, the second position, and the third position of the laser receiving part of the lens group; the first position is located at the entrance end of the laser receiving part; the third position is located at the other end of the laser receiving part and close to the focusing point; the second position is located between the first position and the third position, and is provided with a card slot for assembling the toe plate; the image acquisition module and the cylindrical mirror are in the same plane, and are used for acquiring an optical image of an optical fiber in a specified direction based on the cylindrical mirror, and converting the optical image into a digital signal and transmitting it to a control end; the image acquisition module is also used for stopping the optical image acquisition in the specified direction when the focused light of the cylindrical mirror is captured and coincides with the optical fiber to be engraved in the specified direction.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a three-dimensional focusing lens and a fiber grating writing method based on the lens. Background Art

[0002] Fiber Bragg gratings have great applications in the field of optical communications and optical sensing with optical fibers as carriers. Driven by the huge demand for monitoring parameters such as tension, pressure and temperature in global urban municipal engineering, optical sensing systems with optical fibers as carriers have broken through the limitations of many electronic sensors and gradually become a mainstream direction. Optical sensing systems using fiber Bragg gratings have obvious advantages in this field, such as higher sensing detection accuracy, wider tension detection range and lighter weight of the system itself. They are implanted in the monitored object and are therefore not affected by electromagnetic interference and external harsh environments.

[0003] At present, the production method of fiber Bragg grating is usually to use an excimer laser with high coherence to write the grating through a phase mask. Through the phase mask, the output laser beam will form regular interference fringes and directly irradiate the optical fiber. Because this method has high optical and mechanical stability and high repetition rate, it is used in mass production. However, in the process of writing fiber Bragg grating, there are technical problems such as the complexity and precision requirements of optical path construction, the quality and precision of phase masks, the selection and stability of lasers, and the pretreatment and fixation of optical fibers. In order to solve these problems, it is necessary to continuously optimize the optical path construction technology, improve the accuracy and stability of phase mask production, select lasers with stable performance and strengthen their maintenance, and improve the pretreatment and fixation methods of optical fibers. Summary of the invention

[0004] In order to determine and calibrate the optical path more quickly and accurately while meeting the writing requirements, the purpose of the present invention is to provide a three-dimensional focusing lens and a fiber grating writing method based on the lens. The technical solutions adopted are as follows:

[0005] In a first aspect, the present application provides a three-dimensional focusing lens, wherein the lens integrates a lens group, an image acquisition module, a beam expander, a toe plate, and a cylindrical mirror, wherein:

[0006] The beam expander, the apodization plate, and the cylindrical mirror are respectively embedded in the first position, the second position, and the third position of the laser receiving part of the lens group;

[0007] The first position is located at the entrance end of the laser receiving part;

[0008] The third position is located at the other end of the laser receiving portion, and the other end is close to the focusing point;

[0009] The second position is located between the first position and the third position and is provided with a slot for mounting a toe cut plate;

[0010] The image acquisition module is located in the same plane as the cylindrical mirror, and is used to acquire an optical image of the optical fiber in a specified direction based on the cylindrical mirror, and convert the optical image into a digital signal and transmit it to the control end;

[0011] The image acquisition module is also used to stop the optical image acquisition in the specified direction when the focused light of the cylindrical mirror is captured to coincide with the optical fiber to be engraved in the specified direction.

[0012] Furthermore, a magnification adjustment knob is provided on the periphery of the first position, and the magnification adjustment knob is used to adjust the magnification of the beam expander to achieve different beam diameters and divergence angles.

[0013] Furthermore, the beam expansion ratio of the beam expander is 5, which is used to enlarge the diameter of the incident laser beam by 5 times;

[0014] The size of the apodization plate is 40×60 mm and is used to adjust the energy distribution before the laser is further focused;

[0015] The length, height, radius, center thickness and edge thickness of the cylindrical mirror are 90 mm, 100 mm, 77.5 mm, 21.3 mm and 3 mm respectively, and is used to compress or diverge the laser beam in a specified direction.

[0016] Furthermore, the lens is also integrated with an automatic focusing switch and a slide, wherein:

[0017] The automatic focusing switch is placed on one side of the third position, and is used to trigger the automatic focusing function when the user presses the switch;

[0018] The lens group is placed on a slide table, and is used to carry the lens group and control its front and rear positions for mobile focusing when the automatic focusing function is triggered.

[0019] Furthermore, the lens is also integrated with an adjustment mechanism, wherein:

[0020] The adjustment mechanism is used to obtain a control instruction generated by the control end according to the received digital signal, and control and adjust the lens horizontal movement parameters, lens rotation parameters, and lens tilt parameters according to the control instruction, so that the cylindrical mirror focused light can coincide with the optical fiber to be engraved in a specified direction.

[0021] In a second aspect, the present application further provides a fiber grating writing method applied to any of the above-mentioned three-dimensional focusing lenses, the method comprising:

[0022] S1. Acquire a first digital signal transmitted via the image acquisition module;

[0023] S2. For the X-axis direction, the overall clarity of the optical fiber to be engraved is analyzed based on the first digital signal, and when it is determined that the analysis result is greater than or equal to a preset threshold, a first control instruction corresponding to a forward action is generated, otherwise a second control instruction corresponding to a backward action is generated, wherein the first and second control instructions are transmitted to the adjustment mechanism, and the adjustment mechanism adjusts the horizontal movement parameters of the lens so that the cylindrical mirror focused light and the optical fiber to be engraved can coincide with each other in the X-axis direction;

[0024] S3, when it is determined that the cylindrical mirror focused light coincides with the optical fiber to be engraved in the X-axis direction, acquiring a second digital signal transmitted via the image acquisition module;

[0025] S4, with respect to the Y-axis direction, analyzing the rotation distance based on the second digital signal, and generating a third control instruction corresponding to the rotation action based on the rotation distance, wherein the third control instruction is transmitted to the adjustment mechanism, and the adjustment mechanism performs lens rotation parameters so that the cylindrical mirror focused light and the optical fiber to be engraved can overlap in the Y-axis direction;

[0026] S5. When it is determined that the light focused by the cylindrical mirror coincides with the optical fiber to be engraved in the Y-axis direction, acquiring a third digital signal transmitted via the image acquisition module;

[0027] S6. With respect to the Z-axis direction, a comparative analysis of the clarity of the left and right ends of the optical fiber to be engraved is performed based on the third digital signal, and when it is determined that the clarity of the left end is higher than that of the right end, a fourth control instruction corresponding to the left front tilt is generated, otherwise a fifth control instruction corresponding to the right front tilt action is generated, wherein the fourth and fifth control instructions are transmitted to the adjustment mechanism, and the adjustment mechanism adjusts the lens tilt parameters so that the light focused by the cylindrical mirror and the optical fiber to be engraved can coincide with each other in the Z-axis direction.

[0028] Furthermore, in step S2 and step S6, the clarity analysis is performed based on the following formula:

[0029] ;

[0030] in, N are the vertical and horizontal pixel sizes of the digital image, f ( i , j ) is the spatial domain image at pixel point ( i , j ) is formed at the gray matrix, i , j For the matrix f ( i , j) rows and columns, F( u,v ) is the transformation domain matrix obtained after calculation, which reflects the image clarity. u、v is the matrix F( u,v ) rows and columns.

[0031] Further, in step S4, the analysis of the rotation distance based on the second digital signal in the Y-axis direction includes:

[0032] S41. Based on the sine theorem, when the length of the cylindrical mirror is known to be 2 R , and the angle A between the optical fiber to be engraved and the horizontal direction, the rotation distance is calculated by the following formula a Analysis: a =2 RsinA .

[0033] Furthermore, the method further comprises:

[0034] S7, control the image acquisition module to perform focusing verification on the X-axis, Y-axis, and Z-axis of the cylindrical mirror focused light, and when focusing fails, return to step S1 to re-optimize the focusing parameters and reposition until the cylindrical mirror focused light coincides with the optical fiber to be engraved in three-dimensional space. Otherwise, it is considered that the cylindrical mirror focused light coincides with the optical fiber to be engraved in three-dimensional space.

[0035] The present invention has the following beneficial effects:

[0036] The three-dimensional focusing lens provided by the present application integrates multiple key components such as a lens group, an image acquisition module, a beam expander, a toe cut plate, and a cylindrical mirror, wherein the beam expander located at the entrance end of the receiving laser part can expand the diameter of the laser beam and adjust its divergence angle so that the laser beam can better cover the target area, thereby improving the accuracy and efficiency of focusing. The toe cut plate is located between the beam expander and the cylindrical mirror, which can improve the edge quality of the light beam and reduce the diffraction and scattering effects of the light beam edge. The coordinated work of the cylindrical mirror and the image acquisition module enables real-time acquisition of the optical image of the optical fiber in the specified direction, and converts it into a digital signal and transmits it to the control end. This design enables real-time monitoring of the position and state of the optical fiber to achieve precise alignment in three-dimensional space. Finally, through the information fed back in real time by the image acquisition module, the position and parameters of the lens group, the beam expander, the toe cut plate, and the cylindrical mirror can be automatically adjusted to achieve the best focusing effect. When the cylindrical mirror focused light coincides with the optical fiber to be engraved in the specified direction, the image acquisition module can automatically stop acquisition, thereby reducing unnecessary waste of resources and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic structural diagram of a three-dimensional focusing lens provided by an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of the structural distribution of a three-dimensional focusing lens provided by an embodiment of the present invention;

[0039] Figure 3 A schematic flow chart of a fiber Bragg grating writing method applied to a three-dimensional focusing lens provided by an embodiment of the present invention.

[0040] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0041] 1. First position; 2. Second position; 3. Third position; 4. Magnification adjustment knob; 5. Auto focus switch. DETAILED DESCRIPTION

[0042] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the specific implementation, structure, features and effects of a three-dimensional focusing lens and a fiber grating writing method based on the lens proposed by the present invention in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0043] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0044] The following specifically describes a three-dimensional focusing lens provided by the present invention and a specific solution of a fiber grating writing method based on the lens in conjunction with the accompanying drawings.

[0045] See also Figure 1 and Figure 2, which shows a structural schematic diagram and a structural distribution schematic diagram of a three-dimensional focusing lens provided by an embodiment of the present invention. Based on the figure, it can be seen that the lens integrates a lens group, an image acquisition module, a beam expander, a toe plate, and a cylindrical mirror, wherein: the beam expander, the toe plate, and the cylindrical mirror are respectively embedded in the first position 1, the second position 2, and the third position 3 of the laser receiving part of the lens group; the first position 1 is located at the entrance end of the laser receiving part; the third position 3 is located at the other end of the laser receiving part, and the other end is close to the focusing point; the second position 2 is located between the first position 1 and the third position 3, and is provided with a card slot for mounting the toe plate; the image acquisition module and the cylindrical mirror are in the same plane, and are used to collect the optical image of the optical fiber in the specified direction based on the cylindrical mirror, and convert the optical image into a digital signal and transmit it to the control end; the image acquisition module is also used to stop the optical image acquisition in the specified direction when the focus light of the cylindrical mirror is captured and coincides with the optical fiber to be engraved in the specified direction.

[0046] For details, please refer to Figure 1 , the present application places a beam expander at the entrance end of the lens group where the laser is received, wherein the integration of the beam expander makes it possible to expand the diameter of the laser beam and reduce the divergence angle of the laser beam, thereby achieving the effect of improving the subsequent focusing accuracy. On the other hand, the present application places a cylindrical mirror close to the focusing point, so that a light intensity distribution with a specific geometric shape can be generated on the focusing plane, and automatic focusing can be performed. Finally, the present application places a toe-cutting plate in the card slot at the second position, so that the energy distribution can be adjusted before the laser is further focused, wherein the user can select a matching toe-cutting plate for replacement.

[0047] For details, please refer to Figure 2 The image acquisition module is used in conjunction with the cylindrical mirror to monitor the position and state of the optical fiber to ensure precise alignment in a specific direction. It should be noted that the image acquisition module has a sufficiently high resolution and sensitivity to accurately capture the position and state of the optical fiber. When the control end receives the digital signal, it will analyze the digital signal and generate corresponding control instructions based on the analysis results. The control instructions will be transmitted to the adjustment mechanism integrated in the lens, and the adjustment mechanism will control the corresponding lens parameters based on the received instructions, so that the cylindrical mirror focuses the light and the optical fiber to be engraved in the specified direction.

[0048] As can be seen from the above, the three-dimensional focusing lens provided by the present application integrates multiple key components such as a lens group, an image acquisition module, a beam expander, a toe cut plate, and a cylindrical mirror, wherein the beam expander located at the entrance end of the receiving laser part can expand the diameter of the laser beam and adjust its divergence angle so that the laser beam can better cover the target area, thereby improving the accuracy and efficiency of focusing. The toe cut plate is located between the beam expander and the cylindrical mirror, which can improve the edge quality of the light beam and reduce the diffraction and scattering effects of the light beam edge. The coordinated work of the cylindrical mirror and the image acquisition module enables real-time acquisition of the optical image of the optical fiber in the specified direction, and converts it into a digital signal and transmits it to the control end. This design enables real-time monitoring of the position and state of the optical fiber to achieve precise alignment in three-dimensional space. Finally, through the information fed back in real time by the image acquisition module, the position and parameters of the lens group, the beam expander, the toe cut plate, and the cylindrical mirror can be automatically adjusted to achieve the best focusing effect. When the cylindrical mirror focused light overlaps with the optical fiber to be engraved in the specified direction, the image acquisition module can automatically stop acquisition, thereby reducing unnecessary waste of resources and improving work efficiency.

[0049] In one embodiment, please refer to Figure 1 A magnification adjustment knob 4 is provided on the periphery of the first position 1, and the magnification adjustment knob 4 is used to adjust the magnification of the beam expander to achieve different beam diameters and divergence angles.

[0050] For details, please refer to Figure 1 In the present application, the magnification adjustment knob 4 is placed on the periphery of the beam expander, so that the user can freely operate the button, so that the magnification of the beam expander can be changed according to actual needs to achieve different beam diameters and divergence angles.

[0051] In one embodiment, an auxiliary element may be further provided on the multiple adjustment knob 4, and the auxiliary element includes at least one of a scale and an indicator light. It should be noted that, in order to facilitate the user to understand the current adjustment status in a timely manner, the auxiliary element may be applied to improve the user experience.

[0052] In one of the embodiments, the beam expansion ratio of the beam expander is 5, which is used to enlarge the diameter of the incident laser beam by 5 times; the size of the toe-cutting plate is 40×60 mm, which is used to adjust the energy distribution before the laser is further focused; the length, height, radius, center thickness and edge thickness of the cylindrical mirror are 90 mm, 100 mm, 77.5 mm, 21.3 mm and 3 mm respectively, which is used to compress or diverge the laser beam in a specified direction.

[0053] In one embodiment, please refer to Figure 1 and Figure 2The lens is also integrated with an autofocus switch 5 and a slide, wherein: the autofocus switch 5 is placed on one side of the third position 3, and is used to trigger the autofocus function when the user presses the switch; the lens group is placed on the slide, and is used to carry the lens group and control its front and rear position for moving focusing when the autofocus function is triggered.

[0054] Specifically, in order to control the opening and closing of the automatic focusing function. The present application is provided with an automatic focusing switch 5, and when the user presses the switch, the automatic focusing function will be triggered. It should be noted that before pressing the automatic focusing switch 5, in order to further improve the focusing accuracy, the user needs to manually adjust the lens group to find the most accurate point for the optical fiber to focus. When the user finds the most accurate focusing point through manual calibration, the user presses the automatic focusing switch 5 to set the current position as the reference point. In this way, this reference point is used as a reference in the future automatic focusing process.

[0055] Specifically, the slide is a mechanical structure used to support and move the lens group. It can stably carry the lens group and allow it to perform precise linear movement during the focusing process, so that the laser beam can be focused on the optical fiber.

[0056] In one embodiment, the lens is further integrated with an adjustment mechanism, wherein: the adjustment mechanism is used to obtain the Figure 2 The control mainboard shown in FIG. 1 generates a control instruction according to the received digital signal, and controls and adjusts the lens horizontal movement parameters, lens rotation parameters, and lens tilt parameters according to the control instruction, so that the cylindrical mirror focused light can coincide with the optical fiber to be engraved in the specified direction.

[0057] The lens horizontal movement parameters, lens rotation parameters, and lens tilt parameters cover the basic movement freedom of the lens in three-dimensional space and can meet the alignment requirements.

[0058] Specifically, the adjustment mechanism can accurately respond to the command issued by the control end and perform corresponding adjustment actions accordingly. Among them, the purpose of all adjustment actions is to make the cylindrical mirror focus light and the optical fiber to be engraved coincide in the specified direction.

[0059] For example, please refer to Figure 2 When the control instruction indicates a forward or backward movement in the X-axis direction, the adjustment mechanism will adjust the horizontal movement parameters of the lens according to the instruction, and through the coordinated action of the motor and the transmission mechanism, the cylindrical mirror focused light can be horizontally overlapped with the optical fiber to be engraved.

[0060] For example, please refer to Figure 2When the control instruction indicates the rotation distance in the Y-axis direction, the adjustment mechanism will adjust the lens rotation parameters according to the instruction, and through the precise control of the rotating device, the cylindrical mirror focused light can be vertically overlapped with the optical fiber to be engraved.

[0061] For example, please refer to Figure 2 When the control instruction indicates a left front tilt or right front tilt action in the Z-axis direction, the adjustment mechanism will adjust the lens tilt parameters according to the instruction, and through the precise control of the tilt device, the cylindrical mirror focused light can overlap obliquely with the optical fiber to be engraved.

[0062] Please refer to Figure 3 The present application discloses a fiber grating writing method applied to any of the above-mentioned three-dimensional focusing lenses, the method comprising:

[0063] Step S1, acquiring a first digital signal transmitted via the image acquisition module.

[0064] Specifically, a first digital signal transmitted via an image acquisition module is obtained, which is the starting point of the entire alignment process. The image acquisition module is responsible for capturing image data of the optical fiber and the optical fiber to be engraved, and converting it into a digital signal for subsequent processing.

[0065] Step S2, with respect to the X-axis direction, analyze the overall clarity of the optical fiber to be engraved based on the first digital signal, and when it is determined that the analysis result is greater than or equal to a preset threshold, generate a first control instruction corresponding to a forward action, otherwise generate a second control instruction corresponding to a backward action, wherein the first and second control instructions will be transmitted to the adjustment mechanism, and the adjustment mechanism will adjust the horizontal movement parameters of the lens so that the cylindrical mirror focused light and the optical fiber to be engraved can coincide with each other in the X-axis direction.

[0066] Specifically, the overall clarity of the optical fiber to be engraved at the current lens position can be evaluated by analyzing the image clarity based on the first digital signal. If the clarity is greater than or equal to a preset threshold, the current lens position is considered appropriate, and a first control instruction for a forward action is generated to continue subsequent operations; otherwise, a second control instruction for a backward action is generated to adjust the lens position.

[0067] Step S3, when it is determined that the light focused by the cylindrical mirror coincides with the optical fiber to be engraved in the X-axis direction, a second digital signal transmitted via the image acquisition module is acquired.

[0068] Specifically, after the light focused by the cylindrical mirror coincides with the horizontal X-axis of the optical fiber to be engraved, the second digital signal transmitted by the image acquisition module is used again to analyze the rotation angle of the optical fiber.

[0069] Step S4, with respect to the Y-axis direction, analyzing the rotation distance based on the second digital signal, and generating a third control instruction corresponding to the rotation action based on the rotation distance, wherein the third control instruction will be transmitted to the adjustment mechanism, and the lens rotation parameters will be adjusted by the adjustment mechanism so that the cylindrical mirror focused light and the optical fiber to be engraved can coincide with each other in the Y-axis direction.

[0070] Specifically, the angle deviation between the cylindrical mirror focused light and the optical fiber to be engraved is analyzed based on the second digital signal, and the required rotation distance is calculated accordingly. Then, a third control instruction corresponding to the rotation action is generated based on the rotation distance to adjust the rotation parameters of the lens.

[0071] Step S5, when it is determined that the light focused by the cylindrical mirror coincides with the optical fiber to be inscribed in the Y-axis direction, a third digital signal transmitted via the image acquisition module is acquired.

[0072] Step S6, with respect to the Z-axis direction, a comparative analysis of the clarity of the left and right ends of the optical fiber to be engraved is performed based on the third digital signal, and when it is determined that the clarity of the left end is higher than that of the right end, a fourth control instruction corresponding to the left front tilt is generated, otherwise a fifth control instruction corresponding to the right front tilt action is generated, wherein the fourth and fifth control instructions will be transmitted to the adjustment mechanism, and the adjustment mechanism will adjust the lens tilt parameters so that the cylindrical mirror focused light can coincide with the optical fiber to be engraved in the Z-axis direction.

[0073] Specifically, with respect to the Z-axis direction, a comparative analysis of the imaging clarity of the left and right ends of the optical fiber to be engraved will be performed based on the third digital signal. This step focuses on the difference in clarity between the left and right ends of the optical fiber to determine whether the lens needs to be tilted and adjusted in the Z-axis direction. If the clarity of the left end is higher than that of the right end, a fourth control instruction corresponding to the left front tilt is generated; otherwise, a fifth control instruction corresponding to the right front tilt is generated. Among them, these control instructions will adjust the tilt parameters of the lens to ensure that the focused light of the cylindrical mirror coincides with the optical fiber to be engraved in the Z-axis direction.

[0074] In one embodiment, in step S2 and step S6, the clarity analysis is performed based on the following formula:

[0075] ;

[0076] in, N are the vertical and horizontal pixel sizes of the digital image, f ( i , j ) is the spatial domain image at pixel point ( i , j ) is formed at the gray matrix, i , j For the matrix f (i , j ) rows and columns, F( u,v ) is the transformation domain matrix obtained after calculation, which reflects the image clarity. u、v is the matrix F( u,v ) rows and columns.

[0077] In one embodiment, in step S4, analyzing the rotation distance in the Y-axis direction based on the second digital signal includes:

[0078] S41. Based on the sine theorem, when the length of the cylindrical mirror is known to be 2 R , and the angle A between the optical fiber to be engraved and the horizontal direction, the rotation distance is calculated by the following formula a Analysis: a =2 RsinA .

[0079] In one embodiment, the method further comprises:

[0080] Step S7, controlling the image acquisition module to perform focusing verification on the X-axis, Y-axis, and Z-axis of the cylindrical mirror focused light, and when focusing fails, returning to step S1 to re-optimize the focusing parameters and reposition until the cylindrical mirror focused light coincides with the optical fiber to be engraved in three-dimensional space. Otherwise, it is considered that the cylindrical mirror focused light coincides with the optical fiber to be engraved in three-dimensional space.

[0081] Specifically, the image acquisition module is currently controlled to start working and prepare to capture the image of the cylindrical mirror focused light. Set the focus verification points in the three directions of X-axis, Y-axis and Z-axis, which should cover the possible offset range of the cylindrical mirror focused light. Move the cylindrical mirror or the optical fiber to be engraved in the X-axis direction (usually move one and fix the other), and observe the output of the image acquisition module at the same time. Check whether the focused light is accurately aligned with the center or predetermined position of the optical fiber to be engraved in the X-axis direction. If an offset is found, record the offset and prepare to adjust. Similarly, perform focus verification in the Y-axis direction, observe and record the offset of the focused light. Z-axis focus verification also involves adjusting the distance between the cylindrical mirror and the optical fiber to be engraved to find the best focus depth. By fine-tuning the Z-axis position, observe the size and clarity of the focused light spot to ensure that the light achieves the best focusing effect on the surface or inside of the optical fiber. Finally, based on the focus verification results of the X-axis, Y-axis and Z-axis, determine whether the cylindrical mirror focused light coincides with the optical fiber to be engraved in three-dimensional space. If an offset or unclear focus is found in any direction, the focus is considered to have failed.

[0082] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0083] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A fiber Bragg grating writing method applied to a three-dimensional focusing lens, characterized in that: The method comprises: S1, acquiring a first digital signal transmitted via an image acquisition module; S2. For the X-axis direction, the overall clarity of the optical fiber to be engraved is analyzed based on the first digital signal, and when it is determined that the analysis result is greater than or equal to a preset threshold, a first control instruction corresponding to a forward action is generated, otherwise a second control instruction corresponding to a backward action is generated, wherein the first control instruction and the second control instruction are transmitted to the adjustment mechanism, and the adjustment mechanism adjusts the horizontal movement parameters of the lens so that the cylindrical mirror focused light and the optical fiber to be engraved can coincide with each other in the X-axis direction; S3, when it is determined that the cylindrical mirror focused light coincides with the optical fiber to be engraved in the X-axis direction, acquiring a second digital signal transmitted via the image acquisition module; S4, with respect to the Y-axis direction, analyzing the rotation distance based on the second digital signal, and generating a third control instruction corresponding to the rotation action based on the rotation distance, wherein the third control instruction is transmitted to the adjustment mechanism, and the adjustment mechanism performs lens rotation parameters so that the cylindrical mirror focused light and the optical fiber to be engraved can overlap in the Y-axis direction; S5. When it is determined that the light focused by the cylindrical mirror coincides with the optical fiber to be engraved in the Y-axis direction, acquiring a third digital signal transmitted via the image acquisition module; S6. For the Z-axis direction, a comparative analysis is performed on the clarity of the left and right ends of the optical fiber to be engraved based on the third digital signal, and when it is determined that the clarity of the left end is higher than that of the right end, a fourth control instruction corresponding to the left front tilt is generated, otherwise a fifth control instruction corresponding to the right front tilt action is generated, wherein the fourth control instruction and the fifth control instruction are transmitted to the adjustment mechanism, and the adjustment mechanism adjusts the lens tilt parameters so that the cylindrical mirror focused light and the optical fiber to be engraved can coincide with each other in the Z-axis direction; The three-dimensional focusing lens integrates a lens group, an image acquisition module, a beam expander, an apodization plate, and a cylindrical mirror, wherein: The beam expander, the apodization plate, and the cylindrical mirror are respectively embedded in the first position, the second position, and the third position of the laser receiving part of the lens group; The first position is located at the entrance end of the laser receiving part; The third position is located at the other end of the laser receiving portion, and the other end is close to the focusing point; The second position is located between the first position and the third position and is provided with a slot for mounting a toe cut plate; The image acquisition module is located in the same plane as the cylindrical mirror, and is used to acquire an optical image of the optical fiber in a specified direction based on the cylindrical mirror, and convert the optical image into a digital signal and transmit it to the control end; The image acquisition module is also used to stop the optical image acquisition in the specified direction when the focused light of the cylindrical mirror is captured to coincide with the optical fiber to be engraved in the specified direction.

2. The fiber Bragg grating writing method for a three-dimensional focusing lens according to claim 1, characterized in that: A magnification adjustment knob is provided on the periphery of the first position, and the magnification adjustment knob is used to adjust the magnification of the beam expander to achieve different beam diameters and divergence angles.

3. The fiber Bragg grating writing method for a three-dimensional focusing lens according to claim 1, characterized in that: The beam expansion ratio of the beam expander is 5, which is used to enlarge the diameter of the incident laser beam by 5 times; The size of the apodization plate is 40×60 mm and is used to adjust the energy distribution before the laser is further focused; The length, height, radius, center thickness and edge thickness of the cylindrical mirror are 90 mm, 100 mm, 77.5 mm, 21.3 mm and 3 mm respectively, and is used to compress or diverge the laser beam in a specified direction.

4. The fiber Bragg grating writing method for a three-dimensional focusing lens according to claim 1, characterized in that: The lens is also integrated with an automatic focusing switch and a slide, wherein: The automatic focusing switch is placed on one side of the third position, and is used to trigger the automatic focusing function when the user presses the switch; The lens group is placed on a slide table, and is used to carry the lens group and control its front and rear positions for mobile focusing when the automatic focusing function is triggered.

5. The fiber Bragg grating writing method for a three-dimensional focusing lens according to claim 1, characterized in that: The lens is also integrated with an adjustment mechanism, wherein: The adjustment mechanism is used to obtain a control instruction generated by the control end according to the received digital signal, and control and adjust the lens horizontal movement parameters, lens rotation parameters, and lens tilt parameters according to the control instruction, so that the cylindrical mirror focused light can coincide with the optical fiber to be engraved in a specified direction.

6. The method according to claim 1, characterized in that In step S2 and step S6, the clarity analysis is performed based on the following formula: ； in, N are the vertical and horizontal pixel sizes of the digital image, f ( i , j ) is the spatial domain image at the pixel point ( i , j ) is formed at the gray matrix, i , j For the matrix f ( i , j ) rows and columns, F( u,v ) is the transformation domain matrix obtained after calculation, which reflects the image clarity. u、v is the matrix F( u,v ) rows and columns.

7. The method according to claim 1, characterized in that In step S4, the analysis of the rotation distance based on the second digital signal in the Y-axis direction includes: S41. Based on the sine theorem, when the length of the cylindrical mirror is known to be 2 R , and the angle A between the optical fiber to be engraved and the horizontal direction, the rotation distance is calculated by the following formula a Analysis: a =2 RsinA .

8. The method according to claim 1, characterized in that The method further comprises: S7, control the image acquisition module to perform focusing verification on the X-axis, Y-axis, and Z-axis of the cylindrical mirror focused light, and when focusing fails, return to step S1 to re-optimize the focusing parameters and reposition until the cylindrical mirror focused light coincides with the optical fiber to be engraved in three-dimensional space. Otherwise, it is considered that the cylindrical mirror focused light coincides with the optical fiber to be engraved in three-dimensional space.

Images