A laser device for fine grid p-gate hole cutting

Abstract

The application relates to the field of battery screen laser processing, in particular to a laser device for fine-grid PI grid hole cutting, which comprises a displacement module, which is used for mounting and fixing a screen to be processed and performing X-direction displacement, Y-direction displacement and rotation in an XY plane; a laser processing module, which is used for generating ultraviolet laser and focusing the laser on the screen for cutting; the laser processing module comprises a focusing mechanism moving along a Z axis and a light source for generating annular illumination; and a coaxial imaging module, which is used for collecting images of the screen surface and a laser spot along a laser light path; the application can analyze the direction and position of the electroformed grid line opening of the screen in real time during the cutting process, and can cooperate with a displacement and rotation table capable of adaptive adjustment, an XY displacement table, a Z-direction displacement table and an X-direction displacement platform, so that the laser spot can be located at the center position of the electroformed layer grid line opening during the whole PI film cutting process, and the risk of cutting deviation does not exist.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology for battery screen printing, and more particularly to a laser device for cutting fine PI grid holes. Background Technology

[0002] With the rapid development of the photovoltaic industry, the requirements for screen printing performance, silver paste consumption, printing line shape, and aspect ratio in solar cell silver paste printing are continuously increasing. Full-aperture fine grid screens are gradually replacing traditional woven mesh screens. Compared with pure steel sheet type full-aperture fine grid screens, PI film and steel sheet composite full-aperture fine grid screens have significant advantages. The PI film is hydrophobic, which can prevent silver paste from adhering to the sidewalls and overflowing at the bottom, ensuring uniform printing line shape and aspect ratio. At the same time, the PI film can be laser-cut, and the laser spot can reach the single-micron level, which can meet the processing requirements of the extremely small line width of the fine grid screen. The steel sheet (electroplated layer) mainly plays a structural support role.

[0003] In the current composite screen printing process, a skeleton layer (electroformed layer) is first prepared by electroforming. An electroformed opening slightly larger than the finished grid hole is made on the electroformed layer. Then, a PI film is attached to the surface of the electroformed layer. Finally, a laser is used to cut out fine grid holes at the center position of the electroformed opening on the PI film.

[0004] However, during the processing of composite screen printing plates, the opening width of the PI layer grid holes needs to be controlled within 5-10μm, and some high-end products require it to be reduced to below 5μm. The grid hole size tolerance is required to be ≤±0.8μm, and the tolerance is trending towards further tightening. Slight defocusing of the laser objective lens and drift of optical path components can cause deviations in the spot size, directly leading to the scrapping of the screen printing plate. At the same time, different battery manufacturers have different grid hole specifications, requiring continuous and precise adjustment of the laser spot, which is difficult to achieve with conventional laser cutting equipment.

[0005] Meanwhile, the electroformed layer undergoes unpredictable irregular deformation during fabrication, screen stretching, and composite PI film formation, making it impossible to rely solely on the original CAD drawings to locate the cutting path. The grid holes require laser cutting position offsets to be controlled within 1μm, while the screen printing area can reach 200mm×200mm. A single pixel in a conventional low-magnification camera lens can correspond to a size of hundreds of micrometers, failing to meet the 1-2μm alignment accuracy. If a high-magnification objective lens is used alone, the field of view is extremely small, making it impossible to capture global features and difficult to form a stable 5-10μm focused spot.

[0006] Therefore, we propose a laser device for cutting fine PI grid holes to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of insufficient precision in laser cutting of grid lines in existing technologies, and to propose a laser device for cutting fine PI grid holes.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A laser device for cutting fine PI grid holes includes:

[0010] The displacement module is used to install and fix the screen to be processed, and to perform X-axis displacement, Y-axis displacement, and rotation in the XY plane;

[0011] A laser processing module is used to generate ultraviolet laser and focus the laser onto a screen for cutting. The laser processing module includes a focusing mechanism that moves along the Z-axis and a light source for generating ring illumination.

[0012] A coaxial imaging module is used to acquire images of the screen surface and the laser spot along the laser light path. The coaxial imaging module includes a camera that moves back and forth along the X-axis and a phosphor for converting ultraviolet laser light into visible light.

[0013] The ring-shaped illumination source emits illumination light onto the upper surface of the screen. The reflected light from the screen surface returns along the original optical path and is guided to the coaxial imaging module for imaging. The fluorescent sheet makes the ultraviolet laser visible in the coaxial imaging module, allowing the coaxial imaging module to identify and acquire it.

[0014] In a preferred embodiment of the present invention, the displacement module includes an XY displacement stage and a displacement rotary stage mounted on the XY displacement stage. The displacement rotary stage is used to fix the screen to be processed, so that the screen can move in the X direction and rotate in the XY plane. A limit block is provided on the displacement rotary stage. The limit block is used to fix the position of the screen on the displacement rotary stage, so that the two mutually perpendicular sides of the screen are arranged parallel to the XY direction of movement of the XY displacement stage, and to prevent the screen from sliding relative to the displacement rotary stage during the movement or rotation of the XY displacement stage and the displacement rotary stage.

[0015] In a preferred embodiment of the present invention, the laser processing module includes a pulsed laser, a collimating lens, a zoom beam expander system, a 45° angle mirror, a 90% transmission and 10% reflection beam splitter, and an objective lens arranged sequentially along the laser transmission path. The laser beam emitted by the pulsed laser is collimated by the collimating lens to form parallel light. After the spot size of the parallel light is adjusted by the zoom beam expander system, it is reflected by the 45° angle mirror, then passes through the 90% transmission and 10% reflection beam splitter, and finally is focused onto the screen by the objective lens for cutting.

[0016] In a preferred embodiment of the present invention, the objective lens is fixed on a Z-axis displacement stage, and the Z-axis displacement stage and the objective lens fixed on the Z-axis displacement stage constitute a focusing mechanism; the objective lens is moved in the Z-axis direction by the Z-axis displacement stage to adjust the focal length of the objective lens.

[0017] In a preferred embodiment of the present invention, the objective lens is a dry objective lens with a numerical aperture NA ≥ 0.3. The imaging accuracy b of the objective lens is calculated as b = 0.61λ / NA, where λ is the ultraviolet laser wavelength. Taking λ as 350 nm and NA as 0.3 as an example, the imaging accuracy is 0.7 μm.

[0018] In a preferred embodiment of the present invention, the annular illumination source is an annular upper light source, which is symmetrically arranged with respect to the center of the objective lens and is fixedly mounted on the Z-axis displacement stage. The annular upper light source is used to emit illumination light onto the upper surface of the screen printing plate. The reflected light from the screen printing plate surface is collected by the objective lens, reflected by the 90% transmission and 10% reflection beam splitter, and then focused by the imaging lens onto the photosensitive surface of the camera's CCD sensor for imaging.

[0019] In a preferred embodiment of the present invention, the zoom beam expander system is used to adjust the spot diameter D of the incident parallel light, and the focused spot diameter d satisfies the formula d=2.44λf / D, where λ is the ultraviolet laser wavelength and f is the objective lens focal length.

[0020] In a preferred embodiment of the present invention, the coaxial imaging module includes an X-axis displacement platform, a camera, a phosphor, and an imaging lens;

[0021] The camera is mounted on the X-axis displacement platform, and the phosphor is fixed to the photosensitive surface of the camera's CCD sensor.

[0022] The imaging lens is installed between the 90% transmission and 10% reflection beam splitter and the camera; the phosphor sheet is used to convert the incident ultraviolet laser into visible light for the camera's CCD sensor to recognize and collect.

[0023] In a preferred embodiment of the present invention, the wavelength of the light emitted by the annular upper light source is different from the visible light emitted by the fluorescent sheet, and the wavelength is longer than that of the visible light emitted by the fluorescent sheet. The color of the light emitted by the annular upper light source is different from the color of the visible light emitted by the fluorescent sheet; for example, the light emitted by the light source is red, the light emitted by the fluorescent sheet is green, and the mixture of the two is yellow. By making the color of the annular light source different from the laser color converted by the fluorescent sheet, the camera can clearly distinguish the edge of the screen electroforming opening and the laser spot.

[0024] In a preferred embodiment of the present invention, a control unit is further included. The control unit is electrically connected to the displacement module, the laser processing module, and the coaxial imaging module, respectively. The control unit is used to perform the following operations:

[0025] Based on the images acquired by the coaxial imaging module, the edges of the electroforming openings and laser spot edges of the screen printing plate are identified using image processing algorithms.

[0026] The displacement rotary table and XY displacement table in the control displacement module are adjusted so that the center of the laser spot coincides with the center of the electroforming opening;

[0027] Control the zoom and beam expander system to adjust the laser spot size to the set value;

[0028] During the cutting process, the Z-axis displacement stage is controlled to adjust the focal length of the objective lens in real time to keep the objective lens focused, and the X-axis displacement platform is controlled to drive the camera to reciprocate to monitor the image clarity.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. This invention analyzes the orientation and position of the opening of the electroformed grid lines in real time during the cutting process, and uses an adaptively adjustable rotary table, XY displacement table, Z-axis displacement table and X-axis displacement platform to ensure that the laser spot is always located at the center of the opening of the electroformed grid lines throughout the entire PI film cutting process, eliminating the risk of cutting deviation. At the same time, the size of the laser spot can be measured and adjusted in real time during the cutting process, thereby ensuring that the fine grid lines cut during the cutting process are consistent and uniform, adapting to the processing standards of high-end photovoltaic fine grid screens, and solving the problem of insufficient alignment accuracy of traditional equipment.

[0031] 2. This invention allows for free adjustment of the focused spot size through a variable focus beam expander system, thereby enabling the spot size to be freely changed during the cutting process to allow for customized adjustment and control of the local grating opening, and thus customized cutting of the grating opening according to actual application requirements. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of a laser device for cutting fine PI grid holes according to the present invention;

[0033] Figure 2 This is a schematic diagram of the screen printing structure.

[0034] In the diagram: 1. Pulsed laser; 2. Collimating lens; 3. Zoom beam expander system; 4. 45° angle mirror; 5. 90% transmission, 10% reflection beam splitter; 6. Z-axis displacement stage; 7. Objective lens; 8. Ring-shaped upper light source; 9. Rotation stage; 10. XY displacement stage; 11. Imaging lens; 12. Phosphor sheet; 13. Camera; 14. X-axis displacement platform; 15. Screen printing plate. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Reference Figure 1-2 A laser device for cutting fine PI grid holes includes a displacement module consisting of an XY displacement stage 10 and a displacement rotary stage 9. The displacement rotary stage 9 is a piezoelectric control displacement stage, which is an existing displacement stage. Its displacement accuracy is ≤100nm, its rotation accuracy is ≤1 arcsecond, and the displacement stroke of the displacement rotary stage 9 is greater than or equal to the width of the opening of the screen electroforming plate, and the turning angle stroke is ≥1°.

[0037] Specifically, the rotary table 9 is mounted on the XY displacement table 10. Both the rotary table 9 and the XY displacement table 10 are existing devices. The rotary table 9 is used to fix the screen 15 to be processed, so that the screen 15 can move in the X direction and rotate in the XY plane. The displacement length of the XY displacement table 10 in the X and Y directions is greater than the X and Y lengths of the graphic area of ​​the screen 15, respectively. At the same time, the rotary table 9 is also provided with a limit block. The limit block is used to fix the position of the screen 15 on the rotary table 9, so that the two perpendicular sides of the screen 15 are arranged parallel to the XY movement direction of the XY displacement table 10, and to prevent the screen 15 from sliding relative to the rotary table 9 during the movement or rotation of the XY displacement table 10 and the rotary table 9.

[0038] It also includes a laser processing module consisting of a pulsed laser 1, a collimating lens 2, a zoom beam expander system 3, a 45° angle mirror 4, a 90% transmission and 10% reflection beam splitter 5, and an objective lens 7. This module is used to generate ultraviolet laser and focus the laser onto the screen 15 for cutting. The pulsed laser 1, collimating lens 2, zoom beam expander system 3, 45° angle mirror 4, 90% transmission and 10% reflection beam splitter 5, and objective lens 7 are arranged sequentially along the laser transmission path. The pulsed laser 1 is a nanosecond, picosecond, or femtosecond ultraviolet laser with an emission wavelength of 355nm. The size of the pulsed laser 1 spot is in the range of 3μm-15μm.

[0039] During operation, the laser beam emitted by the pulsed laser 1 is collimated by the collimating lens 2 to form parallel light. After the spot size is adjusted by the zoom beam expanding system 3, the parallel light is reflected by the 45° angle mirror 4, then passes through the 90% transmission and 10% reflection beam splitter, and finally is focused onto the screen 15 by the objective lens 7 for cutting.

[0040] Among them, objective lens 7 is a dry objective lens, and the numerical aperture NA of objective lens 7 is ≥0.3. The imaging accuracy b of objective lens 7 is calculated by the formula b=0.61λ / NA, where λ is the wavelength of ultraviolet laser. Taking λ as 350nm and NA as 0.3 as an example, the imaging accuracy is 0.7μm. Objective lens 7 is fixed on Z-axis displacement stage 6. The Z-axis displacement stage 6 and objective lens 7 fixed on Z-axis displacement stage 6 constitute a focusing mechanism. The focal length of objective lens 7 is adjusted by moving objective lens 7 in the Z-axis direction through Z-axis displacement stage 6.

[0041] Objective lens 7 is also provided with a ring illumination source, which is a ring upper light source 8. The ring upper light source 8 is arranged symmetrically with respect to the center of objective lens 7 and is mounted on Z-axis displacement stage 6. The ring upper light source 8 is used to emit illumination light to the upper surface of screen 15. The reflected light from the surface of screen 15 is collected by objective lens 7, reflected by 90% transmission and 10% reflection beam splitter 5, and then focused by imaging lens 11 onto the photosensitive surface of CCD sensor of camera 13 for imaging.

[0042] Secondly, the zoom beam expanding system 3 is used to adjust the spot diameter D of the incident parallel light. The focused spot diameter d satisfies the formula d=2.44λf / D, where λ is the ultraviolet laser wavelength and f is the focal length of the objective lens 7.

[0043] Above the displacement module is a coaxial imaging module that is linked to the laser processing module. The coaxial imaging module is used to acquire images of the surface of the screen 15 and the laser spot along the laser optical path. It includes an X-axis displacement platform 14, a camera 13, a phosphor sheet 12 and an imaging lens 11.

[0044] The camera 13 is mounted on the X-axis displacement platform 14. The reciprocating displacement range of the X-axis displacement platform 14 is ≤1mm. The displacement of the X-axis displacement platform 14 and the shooting of the camera 13 are linked. The X-axis displacement platform 14 makes a reciprocating motion, and the camera 13 continuously acquires the surface pattern of the screen 15 and the laser cutting image.

[0045] The fluorescent sheet 12 is fixed on the photosensitive surface of the CCD sensor of the camera 13. The fluorescent sheet 12 is used to convert the incident ultraviolet laser into visible light for the CCD sensor of the camera 13 to identify and collect.

[0046] Imaging lens 11 is mounted between 90% transmission and 10% reflection beam splitter 5 and camera 13;

[0047] It should be noted that the wavelength of the light emitted by the ring light source 8 is different from the visible light emitted by the fluorescent sheet 12. The wavelength is longer than that of the visible light emitted by the fluorescent sheet 12. Furthermore, the color of the light emitted by the ring light source 8 is different from the color of the visible light emitted by the fluorescent sheet 12. For example, the light emitted by the light source is red, the light emitted by the fluorescent sheet 12 is green, and the mixture of the two is yellow. By making the color of the ring light source different from the laser color converted by the fluorescent sheet 12, the camera 13 can clearly distinguish the edge of the electroforming opening of the screen 15 from the laser spot used for cutting.

[0048] It also includes a control unit, which is electrically connected to the displacement module, laser processing module, and coaxial imaging module, respectively. The control unit is used to perform the following operations:

[0049] Based on the images acquired by the coaxial imaging module, the edge of the electroforming opening and the edge of the laser spot of the screen 15 are identified by the image processing algorithm.

[0050] The displacement rotary table 9 and XY displacement table 10 in the control displacement module are adjusted so that the center of the laser spot coincides with the center of the electroforming opening;

[0051] The zoom and beam expansion system 3 adjusts the laser spot size to the set value;

[0052] During the cutting process, the Z-axis displacement stage 6 is controlled to adjust the focal length of the objective lens 7 in real time to keep the objective lens 7 focused, and the X-axis displacement platform 14 is controlled to drive the camera 13 to reciprocate to monitor the image clarity.

[0053] In this embodiment, the position of the mark point (the mark point is a precision positioning mark pre-made on the screen 15 to determine the spatial position and orientation of the screen 15) is captured by the camera, and the ultraviolet spot is moved to a position 100-200μm away from the initial cutting point along the Y direction according to the cutting CAD drawing.

[0054] Let the size of the parallel light spot be D, the wavelength of the ultraviolet laser be λ, the focal length of the objective lens be f, and the size of the focused light spot be d. The size of d is estimated by the formula: d = 2.44λf / D. Therefore, the size of the focused light spot d can be freely adjusted by the beam expander system.

[0055] The initial precise values ​​for the cutting grid opening width, cutting direction, and center alignment are precisely set using the following method: After the laser spot reaches the initial cutting position, the annular upper light source 8 and pulsed laser 1 are turned on. The XY displacement stage 10 is rapidly moved back and forth along the Y direction, with a moving length of 50-80μm. The image of the laser spot illuminating the screen 15 is imaged onto the camera 13, forming a straight line of the spot trajectory. The width of the straight line is the size of the spot. Color analysis is performed on the images of the screen 15 and the spot trajectory captured by the camera 13 to distinguish between the screen 15 image and the spot trajectory. Canny operator edge analysis is performed on the captured images to extract the contour lines in the images. The Hough transform algorithm is used to analyze all the contour lines to obtain coarse line positioning. Edge points are taken based on the coarse positioning lines, and the edges are then... The sub-pixel edge position is obtained by parabolic fitting of the edge point. The precise position and angle of all straight lines are obtained by least square fitting of all edge point positions. Based on the color analysis results, the two side edges of the electroforming opening of the screen and the two edge contours of the spot are distinguished. The two side edges of the electroforming opening are the first parallel line group, and the two edge contours of the spot are the second parallel line group. The distance between the second parallel line groups is the current size of the spot. The zoom beam expansion system 3 is adjusted to adjust the laser spot width to the set value required for the width of the cutting grid opening according to the formula d=2.44λf / D. The angle and center line of the first parallel line group and the second parallel line group are calculated. The rotating moving platform is adjusted so that the angle of the first parallel line group is equal to that of the second parallel line group, and the center line of the first parallel line group coincides with the center line of the second parallel line group. The above straight line calculation algorithm is an existing mature algorithm with a positional accuracy of 0.1 pixels and an angle of 0.1°. Assuming the size corresponding to a single pixel is half an imaging accuracy, it can be deduced that the opening width and center alignment accuracy provided by this method are 2*0.7*0.1*2≈0.03μm, which fully meets the requirements of cutting accuracy.

[0056] Secondly, the precise maintenance of the cutting opening width, center position and direction during the cutting process is precisely determined by the following method: the XY displacement stage 10 moves in the Y direction, the ultraviolet laser spot generated by the pulsed laser 1 illuminates the PI film to cut the PI film, and at the same time forms a straight line of light spot on the camera 13. The X-direction displacement platform 14 is set to a reciprocating movement mode centered on the origin. At the same time, the image of the screen 15 is continuously captured by the camera 13. The edge intensity is calculated using the Laplacian algorithm to obtain the value of the X-direction displacement platform 14 corresponding to the focused image. The origin of the X-direction displacement platform 14 is moved, and the objective lens 7 is moved according to the magnification relationship between the objective lens 7 and the imaging lens 11 so that the camera 13 can image a focused image when the X-direction displacement platform 14 is at the origin position.

[0057] After completing the above steps, color analysis is performed on the captured image of screen 15 and the light spot trajectory image to distinguish between the screen 15 image and the light spot trajectory. Canny edge analysis is used to extract the contour lines from the captured image. A straight-line Hough transform algorithm is applied to all contour lines to obtain coarse line localization. Edge points are then identified based on these coarsely localized lines. Parabolic fitting is performed on these edge points to obtain sub-pixel edge positions. Least-squares fitting is then performed on all edge point positions to obtain the precise positions and angles of all straight lines. Based on the color analysis results, the edge lines on both sides of the screen electroforming opening and the light spot are distinguished. The two edge contour lines, the two side edges of the electroformed opening are the first parallel line group, and the two edge contour lines of the light spot are the second parallel line group. The distance between the second parallel line groups is the current size of the light spot. Adjust the zoom beam expansion system 3, and adjust the laser spot width to the set value required for the width of the cutting grid opening according to the formula d=2.44λf / D. Calculate the angle and center line of the first parallel line group and the second parallel line group. Adjust the rotating moving platform so that the angle of the first parallel line group is equal to that of the second parallel line group, and the center line of the first parallel line group coincides with that of the second parallel line group. Repeat the above process continuously during the cutting process.

[0058] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A laser device for cutting fine PI grid holes, characterized in that, include: The displacement module is used to install and fix the screen (15) to be processed, and to perform X-axis displacement, Y-axis displacement and rotation in the XY plane; A laser processing module is used to generate ultraviolet laser and focus the laser onto a screen (15) for cutting. The laser processing module includes a focusing mechanism that moves along the Z-axis and a light source for generating ring illumination. A coaxial imaging module is used to acquire images of the surface of the screen (15) and the laser spot along the laser light path. The coaxial imaging module includes a camera (13) that moves back and forth along the X-axis and a phosphor (12) for converting ultraviolet laser into visible light. The ring-shaped illumination source emits illumination light onto the upper surface of the screen (15). The reflected light from the surface of the screen (15) returns along the original optical path and is guided to the coaxial imaging module for imaging. The fluorescent sheet (12) makes the ultraviolet laser visible in the coaxial imaging module, allowing the coaxial imaging module to identify and collect it.

2. The laser device for cutting fine PI grid holes according to claim 1, characterized in that, The displacement module includes an XY displacement stage (10) and a displacement rotary stage (9) mounted on the XY displacement stage (10). The displacement rotary stage (9) is used to fix the screen to be processed (15), so that the screen (15) can move in the X direction and rotate in the XY plane.

3. The laser device for cutting fine PI grid holes according to claim 1, characterized in that, The laser processing module includes a pulsed laser (1), a collimating lens (2), a zoom beam expander (3), a 45° angle mirror (4), a 90% transmission and 10% reflection beam splitter (5), and an objective lens (7) arranged sequentially along the laser transmission path. The laser beam emitted by the pulsed laser (1) is collimated by the collimating lens (2) to form parallel light. After the size of the light spot is adjusted by the zoom beam expander (3), the parallel light is reflected by the 45° angle mirror (4), then passes through the 90% transmission and 10% reflection beam splitter, and is finally focused onto the screen (15) by the objective lens (7) for cutting.

4. The laser device for cutting fine PI grid holes according to claim 3, characterized in that, The objective lens (7) is fixed on the Z-axis displacement stage (6), and the Z-axis displacement stage (6) and the objective lens (7) fixed on the Z-axis displacement stage (6) constitute a focusing mechanism.

5. The laser device for cutting fine PI grid holes according to claim 4, characterized in that, The objective lens (7) is a dry objective lens (7), and the numerical aperture NA of the objective lens (7) is ≥0.

3.

6. The laser device for cutting fine PI grid holes according to claim 4, characterized in that, The ring-shaped illumination source is an annular upper light source (8), which is arranged symmetrically with respect to the center of the objective lens (7), and is fixedly installed on the Z-axis displacement stage (6).

7. The laser device for cutting fine PI grid holes according to claim 3, characterized in that, The zoom beam expander system (3) is used to adjust the spot diameter D of the incident parallel light. The focused spot diameter d satisfies the formula d=2.44λf / D, where λ is the ultraviolet laser wavelength and f is the focal length of the objective lens (7).

8. The laser device for cutting fine PI grid holes according to claim 3, characterized in that, The coaxial imaging module includes an X-axis displacement platform (14), a camera (13), a phosphor sheet (12), and an imaging lens (11). The camera (13) is mounted on the X-axis displacement platform (14), and the phosphor sheet (12) is fixed on the photosensitive surface of the CCD sensor of the camera (13); The imaging lens (11) is installed between the 90% transmission and 10% reflection beam splitter and the camera (13).

9. The laser device for cutting fine PI grid holes according to claim 6, characterized in that, The wavelength of the light emitted by the annular upper light source (8) is different from the visible light emitted by the fluorescent sheet (12), and the color of the light emitted by the annular upper light source (8) is different from the color of the visible light emitted by the fluorescent sheet (12).

10. The laser device for cutting fine PI grid holes according to claim 1, characterized in that, It also includes a control unit, which is electrically connected to the displacement module, the laser processing module, and the coaxial imaging module, respectively. The control unit is used to perform the following operations: Based on the images acquired by the coaxial imaging module, the edge of the electroforming opening and the edge of the laser spot of the screen (15) are identified by the image processing algorithm. The displacement rotary table (9) and XY displacement table (10) in the control displacement module are adjusted so that the center of the laser spot coincides with the center of the electroforming opening; (3) Control the zoom beam expansion system to adjust the laser spot size to the set value; During the cutting process, the Z-axis displacement stage (6) is controlled to adjust the focal length of the objective lens (7) in real time to keep the objective lens (7) focused, and the X-axis displacement platform (14) is controlled to drive the camera (13) to reciprocate to monitor the image clarity.

Images