A single laser printing device and method with adjustable linewidth

Abstract

This invention relates to a single-laser printing apparatus and method with modulated linewidth. The apparatus includes a focusing unit, a galvanometer unit, and a beam adjustment module and an angle adjustment module sequentially disposed in front of the laser optical path of the focusing unit and the galvanometer unit. The beam adjustment module modulates a circular laser beam into a strip-shaped laser beam, and modulates the length of the strip-shaped laser beam according to the size of the pattern at the printing position when scanning the same straight line. The strip-shaped laser beams remain parallel to each other during galvanometer scanning, achieving uniform laser energy distribution within the variable-width line scanned by the galvanometer. The angle adjustment module modulates the linewidth direction of the strip-shaped laser beam to be perpendicular to the scanning direction of the galvanometer unit. For different positions in each printing area, the beam adjustment module modulates the laser into a strip-shaped laser beam with a width consistent with the width of the image at the printing position, and the angle adjustment module aligns the width direction of the strip-shaped laser beam perpendicular to the scanning direction of the galvanometer. The galvanometer unit only needs to scan once to complete the scanning of one printing area, significantly improving printing efficiency while ensuring printing accuracy.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a single laser printing device and method with adjustable linewidth. Background Technology

[0002] The purpose of SLM metal 3D printers is to manufacture parts by melting metal powder under the heat of a laser beam, cooling and solidifying it, and then stacking it into layers. SLM metal 3D printing has high requirements for the printing laser. It requires a pure single-mode output laser beam with a beam quality M2 of less than 1.1. Lasers with high beam quality usually have low laser power, which cannot be used to further improve printing efficiency. In addition, metal particle splatter in metal 3D printing can also seriously affect the printing quality. These are all common process problems in 3D printing.

[0003] Powder bed laser melting (PBLM) focuses a high-energy fiber laser beam into a small spot with sufficient energy to completely melt a thin layer of metal powder. A pair of scanning mirrors moves the laser across a powder bed, melting the metal powder and allowing it to solidify and connect with the underlying and adjacent layers, forming a molten pool. A protective gas flow passes over a processing tray to protect the hot metal from oxidation and safely remove fumes. The width of the molten pool is larger than the laser spot (approximately 2 to 3 times the spot diameter) because the heat generated by the laser is conducted to the surrounding powder particles, melting them into the moving molten pool. Multiple melting tracks connect and overlap, forming a solid metal layer corresponding to the layering of the part. The melting tracks must be deep enough to partially remelt the underlying metal layer to form a fully dense solid structure. Powder bed laser melting 3D printing equipment builds parts layer by layer in this manner.

[0004] According to the requirements of metal 3D printing technology, the laser power P and scanning speed V usually need to be properly matched, such as... Figure 1 As shown, if the scanning speed is too fast and the laser power is too low, some areas of the part may not melt completely, resulting in porosity due to "insufficient melting." Conversely, if the power applied at the selected speed is too high, the molten pool may overheat, causing the energy to penetrate too deeply, resulting in a "deep hole" effect. Between these two extremes lies an "operating window" within which a good part density can be obtained. Within this window, the laser energy is sufficient to completely melt the powder and the underlying metal layer without penetrating too deeply. It can be seen that simultaneously increasing laser power and scanning speed can improve processing efficiency, which is feasible to some extent. However, both power and speed have limits; once these limits are exceeded, the molten pool becomes unstable and a "spheroidizing" effect occurs. Figure 2As shown, as laser power increases, spatter may also increase, and when the scanning speed is too fast, the molten pool becomes unstable. A high surface tension gradient causes voids to form behind the laser beam. These voids expand as the laser moves, leading to the decomposition of the molten pool and eventual solidification into multiple unconnected spheres.

[0005] Therefore, in metal 3D printing, the aforementioned process characteristics limit the ability to improve part printing efficiency by increasing scanning speed. To improve printing efficiency, larger spot sizes and thicker scanning lines are typically used to print the infill parts, while finer spot sizes are used to print the outlining lines. Patents "CN8799127U" and "CN5867306U" respectively present solutions using dual laser beams and optical zoom systems to scan the infill and outlining areas with thick and fine lines respectively. In these solutions, only one thickness can be selected when printing any scanning line. Due to the complex structure of the pattern, it is impossible to print the detailed structure of the pattern using traditional fixed-thickness scanning lines. To print the fine structure of the pattern, very fine laser beam lines are needed to scan many times, which further reduces printing efficiency. Therefore, traditional printing methods cannot simultaneously achieve both printing efficiency and printing accuracy. Summary of the Invention

[0006] The purpose of this invention is to provide a single laser printing device and method with adjustable linewidth to solve the problem that traditional 3D printing methods cannot simultaneously achieve both printing efficiency and printing accuracy.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: The present invention relates to a single laser printing device with adjustable linewidth, which includes a focusing unit and a galvanometer unit disposed on the laser optical path, and further includes a beam adjustment module and an angle adjustment module, which are disposed in front of the focusing unit and the galvanometer unit in sequence. The beam adjustment module is used to modulate the circular laser into a strip laser, and when scanning the same straight line, it modulates the length of the strip laser in microseconds according to the size of the pattern at the printing position; the strip laser beams are always parallel to each other when the galvanometer is scanning, so as to achieve uniform laser energy distribution within the variable width line of the galvanometer scanning.

[0008] The angle adjustment module is used to modulate the linewidth direction of the elongated laser to be perpendicular to the scanning direction of the galvanometer unit.

[0009] Preferably, the beam adjustment module employs an acousto-optic modulator, which adjusts the laser diffraction angle by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser beams before and after each modulation are tangent or partially overlap, so that the laser beams move at a speed of [missing information] during that round of modulation. v 2. The laser moves at a constant speed and forms a straight trajectory, and the acousto-optic modulator causes the laser to move at a certain speed. v 2. Satisfy v 2 / v 1≥H / D, where, v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time point from the start of inputting ultrasonic waves into the acousto-optic modulator to the stop of inputting ultrasonic waves into the acousto-optic modulator, so that the length and position of the motion trajectory are consistent with the image at the printing position.

[0010] Preferably, the beam adjustment module employs a rotating mirror, which includes multiple reflective mirrors with the same angle between adjacent mirrors. By rotating the mirror at a uniform speed, the laser beam is reflected sequentially through the multiple mirrors, forming multiple motion trajectories. The laser beam is switched on and off so that the length of the motion trajectory formed by each mirror is consistent with the width of the image at the printing position. Furthermore, the rotating mirror causes the laser beam to move at a speed... v 2. Satisfy v 2 / v 1≥H / D, where, v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

[0011] Preferably, the angle adjustment module uses a Dowell prism, which includes two reflective surfaces (top and bottom) and two refractive surfaces (left and right). The elongated laser enters the Dowell prism through one of the refractive surfaces, and after being reflected by the two reflective surfaces, it exits the Dowell prism from the other refractive surface. The length direction of the elongated laser after exiting the Dowell prism is adjusted by rotating the Dowell prism so that it is perpendicular to the scanning direction of the galvanometer unit.

[0012] Preferably, the initial angle of the angle adjustment module is set when the length direction of the elongated laser is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated based on the vector of the image at the printing position, using the following formula: , in, β For the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b2) These are the start and end coordinates of the vector of the image at the printing location, respectively. k This represents the number of reflections of the elongated laser beam within the angle adjustment module.

[0013] This invention also relates to a single laser printing method with modulated linewidth, comprising the following steps: S0. The printing work area is divided into several printing units according to the maximum width of the long strip laser modulated by the beam adjustment module. For each printing unit, printing is performed in the order of S1-S3. S1. The beam adjustment module is used to modulate the circular laser into a long strip laser, and when scanning the same straight line, the length of the long strip laser is modulated in microseconds according to the size of the pattern at the printing position; S2. The linewidth direction of the long strip laser is modulated to be perpendicular to the scanning direction of the galvanometer unit by the angle adjustment module; S3. The long strip laser is focused by the focusing unit and reflected onto the printing surface by the galvanometer unit to complete the printing at that position. Then, the long strip laser is moved to the next printing position by rotating the galvanometer unit and returned to S1 until all positions are printed.

[0014] Preferably, the beam adjustment module in S1 employs an acousto-optic modulator. The acousto-optic modulator adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser beams before and after each modulation are tangent or partially overlap, so that the laser beams move at a speed of [missing information] during that round of modulation. v 2. The laser moves at a constant speed and forms a straight trajectory, and the acousto-optic modulator causes the laser to move at a certain speed. v 2. Satisfy v 2 / v 1≥H / D, where, v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time point from the start of inputting ultrasonic waves into the acousto-optic modulator to the stop of inputting ultrasonic waves into the acousto-optic modulator, so that the length and position of the motion trajectory are consistent with the image at the printing position.

[0015] Preferably, the beam adjustment module in S1 uses a rotating mirror, which includes multiple reflective mirrors with the same angle between adjacent mirrors. By rotating the mirror at a constant speed, the laser is reflected sequentially through the multiple mirrors, thus forming multiple motion trajectories. The laser's switching mechanism ensures that the length of the motion trajectory formed by each mirror is consistent with the width of the image at the printing position. Furthermore, the rotating mirror causes the laser to move at a speed... v 2. Satisfy v 2 / v1≥H / D, where, v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

[0016] Preferably, the angle adjustment module in S2 uses a Dowell prism. The Dowell prism includes two reflective surfaces (top and bottom) and two refractive surfaces (left and right). The elongated laser enters the Dowell prism through one of the refractive surfaces. After being reflected by the two reflective surfaces in the Dowell prism, it exits the Dowell prism from the other refractive surface. The length direction of the elongated laser after exiting the Dowell prism is adjusted by rotating the Dowell prism so that it is perpendicular to the scanning direction of the galvanometer unit.

[0017] Preferably, in step S2, the initial angle of the angle adjustment module is set when the length direction of the elongated laser is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated based on the vector of the image at the printing position, and the calculation formula is as follows: , in, β For the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) These are the start and end coordinates of the vector of the image at the printing location, respectively. k This represents the number of reflections of the elongated laser beam within the angle adjustment module.

[0018] Compared with the prior art, the technical solution provided by this invention has the following advantages: The single-laser printing device with modulated linewidth disclosed in this invention includes a beam adjustment module and an angle adjustment module. The beam adjustment module modulates a circular laser beam into a long strip laser with a linewidth consistent with the image width at the printing position. The angle adjustment module modulates the linewidth direction of the long strip laser to be perpendicular to the scanning direction of the galvanometer unit. By increasing the beam width through beam modulation, the galvanometer unit only needs to scan once for each printing area to achieve the scanning of one printing area. Furthermore, the laser can be switched on and off to scan patterns with finer lines. The pattern printing accuracy is not reduced compared to single-beam laser scanning printing, thus significantly improving printing efficiency while maintaining printing accuracy. Attached Figure Description

[0019] Figure 1 This is a graph showing the relationship between laser power and scanning speed during SLM metal 3D printing. Figure 2 This is a schematic diagram illustrating the phenomenon of unstable molten pool caused by excessively high scanning speed. Figure 3 This is a schematic diagram of the structure of the front-focusing, modulated linewidth single laser printing device involved in the present invention; Figure 4 This is a schematic diagram of the structure of the single laser printing device with adjustable linewidth and post-focusing capability, which relates to the present invention. Figure 5 This is a schematic diagram of the elongated laser modulation principle in Example 1, which uses an acousto-optic modulator as the beam adjustment module. Figure 6 A Dove prism with single reflection; Figure 7 To increase the length of the reflective surface, the Dove prism; Figure 8 To modify the surface shape of the reflective surface of the Dove prism; Figure 9 This is a diagram illustrating the process of adjusting the width of a long strip laser using an acousto-optic modulator in Example 1. Figure 10 This is a schematic diagram of the rotating mirror in Example 2; Figure 11 This is a schematic diagram of the elongated laser modulation principle using a rotating mirror as the beam adjustment module in Example 2; Figure 12 This is a diagram illustrating the process of adjusting the width of the long strip laser by rotating a mirror in Example 2. Among them, 1-beam adjustment module, 2-angle adjustment module, 3-focusing unit, 4-galvanometer unit, and 5-printing working surface. Detailed Implementation

[0020] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments. The following embodiments are used to illustrate the invention, but are not intended to limit the scope of the invention.

[0021] Example 1: This invention relates to a single laser printing apparatus with adjustable linewidth, comprising a focusing unit 3, a galvanometer unit 4, a beam adjustment module 1, and an angle adjustment module 2 disposed on the laser optical path. The focusing unit 3 can be, for example, […]. Figure 3 The front focusing lens group shown is an imaging lens group composed of several convex and concave lenses; the focusing unit 3 can also adopt, for example... Figure 4 The post-focusing method shown employs an FTheta field lens for focusing unit 3. The galvanometer unit 4 includes an X-axis galvanometer and a Y-axis galvanometer. The beam adjustment module 1 and the angle adjustment module 2 are sequentially positioned in front of the focusing unit 3 and the galvanometer unit 4.

[0022] The beam adjustment module 1 is used to modulate a circular laser into a long strip laser. When scanning the same straight line, it modulates the length of the long strip laser in microseconds based on the size of the pattern at the printing position. In this embodiment, the beam adjustment module 1 uses an acousto-optic modulator. The principle of the acousto-optic modulator modulating a circular laser into a long strip laser is as follows: Acousto-optic modulation involves modulating a signal in an acousto-optic crystal, which acts as an electrical signal on an ultrasonic transducer, and then converts it into a mechanical ultrasonic field that changes in electrical signal form. When the light wave passes through the medium, its beam direction is deflected due to grating diffraction. The beam deflection angle is related to the ultrasonic frequency input to the acousto-optic modulator; this is basic knowledge of acousto-optic modulators and will not be elaborated further. Therefore, this embodiment adjusts the laser diffraction angle by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each ultrasonic frequency modulation is the same, and the laser spot is tangent or partially overlaps before and after each modulation, so that the laser spot moves at a speed during that round of modulation. v 2. The laser moves at a constant speed and forms a straight trajectory, and the acousto-optic modulator causes the laser to move at a certain speed. v 2. Satisfy v 2 / v 1≥H / D, where, v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. Thus, the acousto-optic modulator causes the laser to move at a certain speed. v 2 is much greater than the scanning speed of the galvanometer unit. v 1. For example Figure 5 As shown, the acousto-optic modulator first deflects the first-order light diffraction angle using ultrasound. θ 1. The beam spot at this angle hits... θ Position 1, then the acousto-optic modulator changes the ultrasonic frequency, deflecting the first-order light diffraction angle to... θ 2. The beam spot at this angle hits the area shown in the figure. θ Position 2, θ 2 and θ 1. Adjacent, or partially overlapping, but this embodiment only uses adjacent as an example; repeat the above operation to make the light spot hit the target area respectively. θ 3~ θ Position 6, the switching time between each spot is 0.2 µs, the diameter D of each spot is 100 µm, and the galvanometer scanning speed is... v 1 = 2000 mm / s, meaning that when the acousto-optic modulator is sequentially fed... θ 1~ θ When the ultrasonic wave corresponds to 6, the circular light spot forms a trajectory with a ratio, and the speed of the laser movement is affected by the acousto-optic modulator. v 2 is much greater than the scanning speed of the galvanometer unit. v1. The trajectory of this motion, relative to the scanning direction of the galvanometer, can be considered as a long, narrow laser beam. Theoretically, since the length of the long, narrow laser beam needs to be modulated to be perpendicular to the scanning direction of the galvanometer during subsequent scanning, the increasing angle of the acousto-optic modulator forms an angle with the scanning direction of the galvanometer. α Similarly, the speed at which the laser moves is due to the acousto-optic modulator. v 2 is much greater than the scanning speed of the galvanometer unit. v 1, α ≈90°, and when θ 1~ θ When ultrasonic signals are input at all six positions, the width H of the elongated laser can be equal to six times the diameter of the original circular laser. The width H of this elongated laser is the maximum printing width of a single scan by the printing device.

[0023] The angle adjustment module 2 is used to modulate the linewidth direction of the elongated laser beam to be perpendicular to the scanning direction of the galvanometer unit. The angle adjustment module 2 uses a Dowell prism, which includes two reflective surfaces (top and bottom) and two refractive surfaces (left and right). The elongated laser beam enters the Dowell prism through one of the refractive surfaces, is reflected by the two reflective surfaces, and exits the prism through the other refractive surface. The length direction of the elongated laser beam after exiting the prism is adjusted by rotating the Dowell prism to make it perpendicular to the scanning direction of the galvanometer unit. The Dowell prism undergoes at least one reflection. Figure 6 As shown, the length of the reflective surface can also be increased (e.g., Figure 7 (as shown) or change the shape of one of the reflecting surfaces to an isosceles triangle (as shown) Figure 8 The number of reflections is increased in a manner shown in the figure to improve the sensitivity of linewidth modulation.

[0024] Based on the above-mentioned single laser printing device with adjustable linewidth, the single laser printing method with adjustable linewidth in this embodiment includes the following steps: S0. The printing work area is divided into several printing units according to the maximum width H of the long strip laser modulated by the beam adjustment module. That is, the width of each printing unit is not greater than the maximum width H of the long strip laser, preferably equal to the maximum width H. For each printing unit, printing is performed in the order of S1-S3. S1. A beam adjustment module is used to modulate a circular laser beam into a long strip laser. While scanning the same straight line, the length of the long strip laser is modulated in microseconds according to the size of the pattern at the printing position. The acousto-optic modulator adjusts the laser diffraction angle by continuously modulating the ultrasonic frequency. In each round of modulation, the interval between each ultrasonic frequency modulation is the same, and the laser spots are tangent or partially overlapped before and after each modulation. Specifically, the modulation method is as follows: the length and starting position of the motion trajectory are controlled by the time point from the start of ultrasonic input to the acousto-optic modulator to the stop of ultrasonic input, so that the length and position of the motion trajectory are consistent with the image at the printing position. Figure 9 As shown, when printing the first print position from left to right, the acousto-optic modulator cyclically inputs an ultrasonic signal of the response frequency at 6 time points. When printing the second print position from left to right, the acousto-optic modulator does not input an ultrasonic signal at the first time point, but cyclically inputs an ultrasonic signal of the response frequency at the 2nd to 6th time points, and so on. S2. The linewidth direction of the elongated laser is modulated to be perpendicular to the scanning direction of the galvanometer unit using the angle adjustment module. The initial angle of the angle adjustment module is set when the length direction of the elongated laser is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated based on the vector of the image at the printing position. The calculation formula is as follows: , in, β For the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) These are the start and end coordinates of the vector of the image at the printing location, respectively. k This represents the number of reflections of the elongated laser beam within the angle adjustment module. S3. The long strip laser is focused by the focusing unit 3 and reflected onto the printing surface 5 by the galvanometer unit 4 to complete the printing at that position. Then, the long strip laser is moved to the next printing position by rotating the galvanometer unit 4 and returned to S1 until all positions are printed.

[0025] Example 2 Compared with Embodiment 1, this embodiment uses a rotating mirror instead of the acousto-optic modulator as the beam adjustment module 1. The specific structure of the rotating mirror is as follows: Figure 10 As shown, the system includes multiple reflective mirrors with the same angle between adjacent mirrors. A rotating mirror at a constant speed causes the laser to be reflected sequentially through these mirrors, forming multiple motion trajectories. The laser's on / off state ensures that the length of the motion trajectory formed by each mirror is consistent with the width of the image at the printing position. Furthermore, the rotating mirror causes the laser to move at a speed... v2. Satisfy v 2 / v 1≥H / D, where, v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

[0026] The principle of a rotating mirror modulating a circular laser beam into a long, thin beam is as follows: The scanning speed of the galvanometer unit 4 is typically very slow. Taking the scanning speed commonly used in metal 3D printing as an example, the scanning speed at the printing surface is usually 1000~2000 mm / s, and the working distance of the galvanometer unit 4 is 400~800 mm. Assuming a scanning speed of 2000 mm / s and a working distance of 500 mm, the scanning angular velocity of the laser beam is 4 rad / s, and the rotational angular velocity of unit 4 is 2 rad / s, or 19.1 revolutions per minute. The rotational speed of the rotating mirror can typically exceed 60,000 revolutions per minute; therefore, the angular velocity of the rotating mirror is more than 3000 times the working angular velocity of the galvanometer. Figure 11 As shown, when a circular laser beam enters the edge of one of the reflecting mirrors of the rotating mirror, the mirror rotates at a constant speed, and the circular laser spot forms a trajectory with a ratio. Since the rotational speed of the rotating mirror is much greater than the rotational speed of the galvanometer unit, this trajectory can be regarded as a long strip of laser beam relative to the scanning direction of the galvanometer. The scanning distance of the single reflecting mirror is the length H of the trajectory. Theoretically, since the length direction of the long strip of laser beam needs to be modulated to be perpendicular to the scanning direction of the galvanometer during subsequent scanning, there is an angle between the scanning direction of the rotating mirror and the scanning direction of the galvanometer. α Similarly, since the rotational speed of the rotating mirror is much greater than the rotational speed of the galvanometer unit, α The width H of the elongated laser beam is approximately 90°, which is the maximum printing width of a single scan by the printing device. Assuming the reflecting mirror of the rotating mirror is an equilateral N-sided polygon, the equivalent scanning distance of the rotating mirror is L. When the rotating mirror rotates, the angle that the laser can scan through each side is 4π / N. For more flexible scanning patterns, a polygonal rotating mirror with a relatively large N can usually be selected. When N is relatively large, the scanning length H of the laser beam on the printing surface after passing through the rotating mirror can be approximately expressed as: H = 4πL / N.

[0027] Based on the above-mentioned single laser printing device with adjustable linewidth, the single laser printing method with adjustable linewidth in this embodiment includes the following steps: S0. The printing work area is divided into several printing units according to the maximum width H of the long strip laser modulated by the beam adjustment module. That is, the width of each printing unit is not greater than the maximum width H of the long strip laser, preferably equal to the maximum width H. For each printing unit, printing is performed in the order of S1-S3. S1. A beam adjustment module modulates a circular laser beam into a long strip laser. While scanning the same straight line, the length of the long strip laser is modulated in microseconds based on the size of the pattern at the printing position. A rotating mirror at a uniform speed causes the laser to be reflected sequentially by multiple reflective mirrors, thus forming multiple motion trajectories. The laser's switching mechanism ensures that the length of the motion trajectory formed by each reflective mirror is consistent with the width of the image at the printing position. Specifically, the modulation method is as follows: The laser's switching mechanism ensures that the length of the motion trajectory formed by each reflective mirror is consistent with the width of the image at the printing position. Figure 12 As shown, when the rotating mirror scans to the dashed line position, the laser is turned off; when the rotating mirror scans to the solid line position, the laser is turned on to adapt to the image width at different positions. S2. The linewidth direction of the elongated laser is modulated to be perpendicular to the scanning direction of the galvanometer unit using the angle adjustment module. The initial angle of the angle adjustment module is set when the length direction of the elongated laser is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated based on the vector of the image at the printing position. The calculation formula is as follows: , in, β For the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) These are the start and end coordinates of the vector of the image at the printing location, respectively. k This represents the number of reflections of the elongated laser beam within the angle adjustment module. S3. The long strip laser is focused by the focusing unit 3 and reflected onto the printing surface 5 by the galvanometer unit 4 to complete the printing at that position. Then, the long strip laser is moved to the next printing position by rotating the galvanometer unit 4 and returned to S1 until all positions are printed.

[0028] The present invention has been described in detail above with reference to the embodiments, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A single laser printing device with modulated linewidth, comprising a focusing unit and a galvanometer unit disposed in the laser optical path, characterized in that: It also includes a beam adjustment module and an angle adjustment module, which are sequentially arranged in front of the laser optical path of the focusing unit and the galvanometer unit; The beam adjustment module is used to modulate a circular laser beam into a long strip laser beam, and when scanning the same straight line, it modulates the length of the long strip laser beam in microseconds according to the size of the pattern at the printing position; the long strip laser beams are always parallel to each other during galvanometer scanning, so as to achieve uniform laser energy distribution within the variable width line scanned by the galvanometer; the beam adjustment module uses an acousto-optic modulator or a rotating mirror; When an acousto-optic modulator is used, it adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser spot is tangent or partially overlapped before and after each modulation. This makes the laser spot move at a constant speed v2 during the modulation round and form a straight motion trajectory. The acousto-optic modulator makes the laser moving speed v2 satisfy v2 / v1≥H / D, where v1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time point from the start of inputting ultrasonic waves into the acousto-optic modulator to the stop of inputting ultrasonic waves into the acousto-optic modulator, so that the length and position of the motion trajectory are consistent with the image at the printing position. When a rotating mirror is used, the rotating mirror includes multiple reflecting mirrors with the same included angle between adjacent reflecting mirrors. By rotating the rotating mirror at a constant speed, the laser is reflected sequentially through multiple reflecting mirrors, thus forming multiple motion trajectories. In conjunction with the laser's switching, the length of the motion trajectory formed by each reflecting mirror is consistent with the width of the image at the printing position. Furthermore, the speed v2 of the laser movement caused by the rotating mirror satisfies v2 / v1≥H / D, where v1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The angle adjustment module is used to modulate the linewidth direction of the elongated laser to be perpendicular to the scanning direction of the galvanometer unit. The angle adjustment module uses a Dowell prism, which includes two reflective surfaces (top and bottom) and two refractive surfaces (left and right). The elongated laser enters the Dowell prism through one of the refractive surfaces, and after being reflected by the two reflective surfaces, it exits the Dowell prism from the other refractive surface. The length direction of the elongated laser after exiting the Dowell prism is adjusted by rotating the Dowell prism so that it is perpendicular to the scanning direction of the galvanometer unit.

2. The single laser printing device with adjustable linewidth according to claim 1, characterized in that: The initial angle of the angle adjustment module is set when the length direction of the elongated laser is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated based on the vector of the image at the printing position. The calculation formula is as follows: ， Where β is the rotation angle of the angle adjustment module, (a1, b1) and (a2, b2) are the starting and ending coordinates of the vector of the image at the printing position, respectively, and k is the number of reflections of the long strip laser in the angle adjustment module.

3. A single laser printing method with adjustable linewidth, characterized in that, It includes the following steps: S0. The printing work area is divided into several printing units according to the maximum width of the long strip laser modulated by the beam adjustment module. For each printing unit, printing is performed in the order of S1-S3. S1. A circular laser beam is modulated into a long strip laser beam using a beam adjustment module. When scanning the same straight line, the length of the long strip laser beam is modulated in microseconds according to the size of the pattern at the printing position. The beam adjustment module uses an acousto-optic modulator or a rotating mirror. When using an acousto-optic modulator, the modulator adjusts the laser diffraction angle by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each ultrasonic frequency modulation is the same, and the laser spot is tangent or partially overlaps before and after each modulation. This causes the laser spot to move at a constant speed v2 during the modulation round, forming a straight motion trajectory. The acousto-optic modulator ensures that the laser moving speed v2 satisfies v2 / v1≥H / D, where v1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time point from the start of inputting ultrasonic waves to the stop of inputting ultrasonic waves to the acousto-optic modulator, so that the length and position of the motion trajectory are consistent with the image at the printing position. When a rotating mirror is used, the rotating mirror includes multiple reflecting mirrors with the same included angle between adjacent reflecting mirrors. By rotating the rotating mirror at a constant speed, the laser is reflected sequentially through multiple reflecting mirrors, thus forming multiple motion trajectories. In conjunction with the laser's switching, the length of the motion trajectory formed by each reflecting mirror is consistent with the width of the image at the printing position. Furthermore, the speed v2 of the laser movement caused by the rotating mirror satisfies v2 / v1≥H / D, where v1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. S2. The linewidth direction of the elongated laser is modulated to be perpendicular to the scanning direction of the galvanometer unit by the angle adjustment module. The angle adjustment module adopts a Daowei prism, which includes two reflective surfaces at the top and bottom and two refractive surfaces at the left and right. The elongated laser enters the Daowei prism through one of the refractive surfaces, and after being reflected by the two reflective surfaces in the Daowei prism, it exits the Daowei prism from the other refractive surface. The length direction of the elongated laser after exiting the Daowei prism is adjusted by rotating the Daowei prism so that it is perpendicular to the scanning direction of the galvanometer unit. S3. The long strip laser is focused by the focusing unit and reflected onto the printing surface by the galvanometer unit to complete the printing at that position. Then, the long strip laser is moved to the next printing position by rotating the galvanometer unit and returned to S1 until all positions are printed.

4. The single laser printing method with adjustable linewidth according to claim 3, characterized in that: In step S2, the initial angle of the angle adjustment module is set when the length direction of the elongated laser is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated based on the vector of the image at the printing position. The calculation formula is as follows: ， Where β is the rotation angle of the angle adjustment module, (a1, b1) and (a2, b2) are the starting and ending coordinates of the vector of the image at the printing position, respectively, and k is the number of reflections of the long strip laser in the angle adjustment module.

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