Dynamic focus scanning galvanometer system and multi-beam print head

Abstract

This invention provides a dynamic focusing scanning galvanometer system and a multi-beam printhead, relating to the field of multi-laser powder bed fused additive manufacturing technology. It includes: a dynamic focusing module, a reflector adjustment module, and a galvanometer module arranged sequentially along the optical path transmission direction. The dynamic focusing module includes a first lens movable along the optical axis, and a second and third lens fixedly arranged. The first lens is used to adjust the focusing position of the laser beam in the Z-axis direction. The reflector adjustment module includes a reflector used to reflect and guide the laser beam to the galvanometer module. The galvanometer module includes an X-axis galvanometer and a Y-axis galvanometer, which receive and deflect the laser beam to achieve scanning of the laser beam within the working plane. The system and printhead provided by this invention, by setting a movable first lens and fixed second and third lenses, adjust the focusing position, dynamically compensate for the focal plane shift caused by galvanometer deflection, and improve the quality and consistency of the focused spot within the scanning range.

Description

Technical Field

[0001] This invention relates to the field of multi-laser powder bed fused additive manufacturing technology, and in particular to a dynamic focusing scanning galvanometer system and a multi-beam printhead. Background Technology

[0002] Laser powder bed fusion (LPBF) additive manufacturing technology is widely used in aerospace, energy equipment, and high-end manufacturing fields due to its high forming accuracy and wide material applicability. However, limited by the effective scanning range of the laser scanning system, the forming size of traditional single-laser LPBF equipment is usually no more than 250 mm × 250 mm, which is difficult to meet the needs of large components or high-efficiency manufacturing.

[0003] To increase forming size and improve forming efficiency, existing technologies have proposed multi-laser LPBF (Liquid Laser-Based Printing) schemes, which involve arranging multiple laser beams within the same forming plane and using multiple scanning galvanometer systems to work collaboratively to achieve large-format coverage. This type of scheme typically relies on stitching together multiple scanning areas to achieve full-format printing, but problems such as discontinuous energy density and unstable melt pool behavior can easily occur within the stitched areas, leading to a decrease in forming quality. On the other hand, existing scanning galvanometer systems mostly use F-Theta field lenses for scanning focusing. As the scanning area increases, F-Theta field lenses tend to produce significant aberrations in the edge regions, with noticeable degradation in the size and shape of the focused spot. Furthermore, the aperture and cost of the field lens increase rapidly, limiting its application in large-format, high-consistency scanning scenarios.

[0004] Therefore, how to improve the high-quality effective scanning area of ​​each single laser beam in a multi-beam LPBF system in order to achieve high-quality, full-coverage, seamless printing of large components has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] This invention provides a dynamic focusing scanning galvanometer system and a multi-beam printhead to solve the defects of traditional scanning systems in the prior art, which rely on large-aperture F-Theta field lenses, resulting in significant edge aberrations and high costs during large-format scanning, and to achieve high-quality, full-coverage, seamless printing of large components.

[0006] This invention provides a dynamic focusing scanning galvanometer system, comprising a dynamic focusing module, a mirror adjustment module, and a galvanometer module arranged sequentially along the optical path transmission direction; The dynamic focusing module includes a first lens that is movable along the optical axis, and a second and third lens that are fixedly disposed, for transmitting a laser beam; the laser beam passes sequentially through the first lens, the second lens, and the third lens along the optical path; the first lens is used to adjust the focusing position of the laser beam in the Z-axis direction; The reflector adjustment module includes at least one fixed reflector for reflecting and guiding the laser beam emitted from the dynamic focusing module to the galvanometer module. The galvanometer module includes an X-axis galvanometer and a Y-axis galvanometer; both the X-axis galvanometer and the Y-axis galvanometer are planar reflectors; the X-axis galvanometer and the Y-axis galvanometer are used to sequentially receive and deflect the laser beam to achieve scanning of the laser beam in the working plane.

[0007] In some embodiments, the galvanometer module is located at the far end of the optical path, and the laser beam emitted from the Y-axis galvanometer is directly focused onto the working plane.

[0008] In some embodiments, the first lens is a negative lens; the second lens is a positive lens; and the third lens is a positive lens.

[0009] In some embodiments, the first lens is a meniscus negative lens, and the radius of curvature of the front surface of the first lens is... The radius of curvature of the rear surface is ; The second lens is a plano-convex positive lens, and the radius of curvature of the front surface of the second lens is... The rear surface is flat; The third lens is a plano-convex positive lens, and the radius of curvature of the front surface of the third lens is... The back surface is flat.

[0010] In some embodiments, the convex surfaces of the second lens and the third lens are both disposed facing the first lens.

[0011] In some embodiments, the materials of the first lens, the second lens, and the third lens have a refractive index of 1.46 and an Abelian coefficient of 67.8.

[0012] In some embodiments, the deflection axis of the X-axis galvanometer and the deflection axis of the Y-axis galvanometer are spatially arranged to be perpendicular to each other.

[0013] In some embodiments, the maximum mechanical deflection angle of the X-axis galvanometer and the Y-axis galvanometer is not less than .

[0014] The present invention also provides a multi-beam printhead, comprising multiple dynamic focusing scanning galvanometer systems, wherein the multiple dynamic focusing scanning galvanometer systems are arranged in parallel and together scan and cover the same forming plane.

[0015] In some embodiments, the scanning areas corresponding to adjacent dynamic focusing scanning galvanometer systems have overlapping coverage areas.

[0016] The dynamic focusing scanning galvanometer system and multi-beam printhead provided by this invention, by setting a movable first lens and fixed second and third lenses in the dynamic focusing module, and adjusting the Z-axis focusing position by moving the first lens, dynamically compensates for the focal plane shift caused by galvanometer deflection in real time, so that the laser beam can be stably focused in a large area without the need for an F-Theta field lens, and ensures the quality of the edge spot. Combined with a mirror adjustment module including a fixed mirror and a galvanometer module including mutually perpendicular X-axis and Y-axis plane mirrors, in a multi-beam LPBF system, the high-quality effective scanning area of ​​each single laser beam is improved, the quality and consistency of the focused spot within the scanning range are significantly improved, the dependence of the multi-beam system on splicing scanning is reduced, and thus the forming quality, system reliability and printing efficiency of multi-beam laser powder bed fused additive manufacturing are improved. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the dynamic focusing scanning galvanometer system provided by the present invention.

[0020] Figure 2 This is a schematic diagram of the optical path structure of the dynamic focusing module of the dynamic focusing scanning galvanometer system provided by the present invention.

[0021] Figure 3 This is a partially enlarged schematic diagram of the optical path structure of the dynamic focusing scanning galvanometer system provided by the present invention.

[0022] Figure 4 This is a schematic diagram of the optical path structure of the dynamic focusing scanning galvanometer system provided by the present invention.

[0023] Figure 5This is an optimized front view diagram of the dynamic focusing scanning galvanometer system provided by the present invention.

[0024] Figure 6 This is an optimized dot plot of the dynamic focusing scanning galvanometer system provided by the present invention.

[0025] Figure 7 This is one of the energy distribution diagrams before optimization of the dynamic focusing scanning galvanometer system provided by this invention.

[0026] Figure 8 This is the second energy distribution diagram of the dynamic focusing scanning galvanometer system provided by the present invention before optimization.

[0027] Figure 9 This is the third energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention before optimization.

[0028] Figure 10 This is the fourth energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention before optimization.

[0029] Figure 11 This is the fifth energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention before optimization.

[0030] Figure 12 This is one of the optimized energy distribution diagrams of the dynamic focusing scanning galvanometer system provided by the present invention.

[0031] Figure 13 This is the second optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention.

[0032] Figure 14 This is the third optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention.

[0033] Figure 15 This is the fourth optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention.

[0034] Figure 16 This is the fifth optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps, units, or modules is not necessarily limited to those explicitly listed, but may include other steps, units, or modules not explicitly listed or inherent to such processes, methods, products, or devices.

[0037] Figure 1 This is a schematic diagram of the dynamic focusing scanning galvanometer system provided by the present invention, as shown below. Figure 1 As shown, the system includes a dynamic focusing module 110, a mirror adjustment module 120, and a galvanometer module 130 arranged sequentially along the optical path transmission direction.

[0038] The dynamic focusing module 110 includes a first lens that is movably disposed along the optical axis, and a second lens and a third lens that are fixedly disposed, for transmitting a laser beam; the laser beam passes through the first lens, the second lens and the third lens in sequence along the optical path; the first lens is used to adjust the focusing position of the laser beam in the Z-axis direction; The reflector adjustment module 120 includes at least one fixed reflector for reflecting and guiding the laser beam emitted from the dynamic focusing module to the galvanometer module. The galvanometer module 130 includes an X-axis galvanometer and a Y-axis galvanometer; both the X-axis galvanometer and the Y-axis galvanometer are planar reflectors; the X-axis galvanometer and the Y-axis galvanometer are used to sequentially receive and deflect the laser beam to realize the scanning of the laser beam in the working plane.

[0039] Specifically, the dynamic focusing scanning galvanometer system provided in this embodiment of the invention is mainly used to ensure that the laser beam is always focused on the working plane during large-format scanning, thereby achieving large-format, high-consistency scanning without the need for an F-Theta field lens.

[0040] The dynamic focusing module is located at the front end of the system's optical path. Figure 2 This is a schematic diagram of the optical path structure of the dynamic focusing module of the dynamic focusing scanning galvanometer system provided by the present invention, as shown below. Figure 2As shown, the dynamic focusing module includes a first lens, a second lens, and a third lens, wherein the first lens is movable along the optical axis and serves as a dynamic focusing mirror. By controlling the position change of the first lens along the optical axis, the equivalent focal length of the system can be adjusted, thereby changing the focusing position of the laser beam in the Z-axis direction to compensate for the focal plane shift caused by the galvanometer deflection. In this embodiment of the invention, the wavelength of the laser beam is... .

[0041] In actual two-dimensional scanning, as the scanning point moves away from the center of the working plane, the spatial optical path of the laser beam from the galvanometer to the working plane gradually increases, resulting in focal plane shift, meaning the focus cannot accurately fall on the same plane. To overcome this physical limitation, this embodiment of the invention adjusts the focusing position of the laser beam in the Z-axis direction by moving the first lens. Driven by the control system, the first lens performs high-frequency, continuous translational motion along the optical axis, thereby changing the equivalent focal length of the entire dynamic focusing module and dynamically compensating for the focal plane shift caused by the deflection of the X-axis and Y-axis galvanometers. This real-time dynamic compensation mechanism allows the system to break free from the constraints of traditional large-aperture F-Theta field lenses, ensuring the consistency of the scanning spot from the source. In this embodiment, the movement of the first lens is 2-6 mm, corresponding to an equivalent focal length adjustment range of 80-150 mm. For example, when the movement of the first lens is approximately 4 mm, the corresponding focusing position adjustment range is approximately 120 mm.

[0042] Figure 3 This is a partially enlarged schematic diagram of the optical path structure of the dynamic focusing scanning galvanometer system provided by the present invention, as shown below. Figure 3 As shown, a mirror adjustment module is set after the dynamic focusing module. The mirror adjustment module includes a fixed plane mirror used to change the propagation direction of the laser beam and guide it to the galvanometer module. It should be noted that by properly setting the size of the fixed mirror and the distance between it and the third lens, the laser beam can be guaranteed to have good beam quality and transmission stability before entering the galvanometer module.

[0043] In this embodiment of the invention, the laser beam, after being dynamically focused by the dynamic focusing module, then enters the mirror adjustment module. This module structurally includes at least one fixed mirror. Its main function is to receive the laser beam from the dynamic focusing module and reflect and guide it to the galvanometer module. Introducing the mirror adjustment module has two significant advantages: firstly, by physically folding the optical path using a planar mirror, the axial geometry of the system can be significantly shortened, making the entire scanning head structure more compact and extremely beneficial for high-density side-by-side arrangement in multi-beam printing equipment; secondly, by rationally designing the spatial spacing between the fixed mirror and the preceding and following optical elements, excellent beam quality and transmission stability of the laser beam can be further ensured before entering the high-speed deflecting galvanometer.

[0044] The laser beam, guided by folding, enters the galvanometer module at the end of the optical path. This galvanometer module includes an X-axis galvanometer and a Y-axis galvanometer positioned perpendicularly to each other. Both are planar reflector structures, and their surfaces are typically coated with a dielectric film with a high damage threshold. Parameters such as the dimensions of the X-axis and Y-axis galvanometers, the distance between them, and the distance between the fixed reflector and the X-axis galvanometer are set based on the beam diameter and divergence angle reflected from the reflector adjustment module to the X-axis galvanometer.

[0045] In operation, the X-axis and Y-axis galvanometers receive the laser beam from the reflector adjustment module and drive the two reflectors with a high-speed motor to generate precise angular deflection, thereby realizing two-dimensional scanning of the laser beam in the working plane.

[0046] Figure 4 This is a schematic diagram of the optical path structure of the dynamic focusing scanning galvanometer system provided by the present invention, as shown below. Figure 4 As shown, in this embodiment of the invention, the laser beam passes sequentially through a first lens, a second lens, and a third lens along the optical path, and is then reflected by a fixed reflector, an X-axis galvanometer, and a Y-axis galvanometer before finally focusing onto the working plane. By synchronously adjusting the position of the first lens during the scanning process, dynamic compensation can be achieved for focal plane shifts caused by different galvanometer deflection angles, ensuring that the laser beam can be stably focused on the working plane at different scanning positions. In this embodiment of the invention, the system can focus the laser beam on the working plane within a scanning range of not less than 500 mm × 500 mm, and the diameter of the focused spot is not greater than [missing information]. .

[0047] The dynamic focusing scanning galvanometer system provided in this invention provides a dynamic focusing module with a movable first lens and fixed second and third lenses. By moving the first lens to adjust the Z-axis focusing position, the system dynamically compensates for focal plane shift caused by galvanometer deflection in real time. This allows the laser beam to be stably focused within a large area without the need for an F-Theta field lens, ensuring the quality of the edge spot. Combined with a mirror adjustment module containing a fixed mirror and a galvanometer module containing mutually perpendicular X-axis and Y-axis planar mirrors, this system improves the high-quality effective scanning area of ​​each single laser beam in a multi-beam LPBF system. It significantly improves the quality and consistency of the focused spot within the scanning range, reduces the dependence of the multi-beam system on stitched scanning, and thus improves the forming quality, system reliability, and printing efficiency of multi-beam laser powder bed fused additive manufacturing.

[0048] In some embodiments, the galvanometer module is located at the far end of the optical path, and the laser beam emitted from the Y-axis galvanometer is directly focused onto the working plane.

[0049] Specifically, in this embodiment of the invention, the galvanometer module is located at the very end of the optical path. Within the entire scanning galvanometer system, after the laser beam passes sequentially through the lens group of the dynamic focusing module, the reflector adjustment module, and the deflection of the X-axis and Y-axis galvanometers, no lens elements with optical power, such as flat lenses, are placed in the optical path.

[0050] Based on the above arrangement, the laser beam emitted from the Y-axis galvanometer is directly focused on the working plane and finally converges into a high-quality micro-spot that meets the process requirements in the forming area, i.e., the working plane where the laser powder bed is located.

[0051] This design, which places the galvanometer module at the very end of the optical path and focuses the laser beam "straight out," completely eliminates the need for traditional F-Theta field lenses. Traditional scanning systems heavily rely on F-Theta field lenses to correct spherical focal plane errors caused by galvanometer deflection. However, this embodiment of the invention utilizes a front-mounted dynamic focusing module to achieve active, real-time compensation of the Z-axis focal length, structurally eliminating the need for bulky and expensive field lenses.

[0052] Furthermore, by eliminating the field lens, the system is no longer limited by its optical aperture, completely eliminating the significant aberrations that large-aperture field lenses are prone to produce in the edge scanning region. This allows the laser beam to maintain extremely high roundness, extremely small size, and concentrated energy distribution at the edge of the scanning area, even within extreme scanning areas such as 600 mm × 600 mm or larger.

[0053] Finally, the field-lens-less design significantly reduces the overall weight of the printhead and shrinks its longitudinal and lateral volume, making the scanning galvanometer system extremely compact. This compactness provides an excellent hardware foundation for subsequent multi-beam printhead arraying, enabling multiple independent scanning systems to be arranged side-by-side at high density above the same forming plane, thereby achieving seamless, full-coverage scanning and printing of the forming area by multiple laser beams.

[0054] The dynamic focusing scanning galvanometer system provided in this invention, by abandoning the traditional F-Theta field lens and placing the galvanometer module at the far end of the optical path with the laser beam "directly" focused, overcomes the physical limitations of traditional large-aperture field lenses on scanning area and high cost. It effectively eliminates significant aberrations that are easily generated in the edge areas of a large field of view, thereby significantly improving the roundness, energy concentration, and size consistency of the focused spot over a large area. At the same time, this field lens-free design greatly reduces the overall size and weight of the system, greatly facilitating the high-density parallel integration of multiple scanning units in a multi-beam printhead. This lays the core structural foundation for completely solving the pain point of quality degradation in traditional splicing areas and realizing seamless full-coverage printing with multiple laser beams.

[0055] In some embodiments, the first lens is a negative lens; the second lens is a positive lens; and the third lens is a positive lens.

[0056] Specifically, in the dynamic focusing module of this embodiment of the invention, the first lens is a negative lens; the second lens is a positive lens; and the third lens is a positive lens.

[0057] A negative lens is a lens whose center thickness is less than its edge thickness, and it primarily functions to diverge light beams. A positive lens is a lens whose center thickness is greater than its edge thickness, and it primarily functions to converge light beams.

[0058] The dynamic focusing scanning galvanometer system provided in this embodiment of the invention, by adopting this "one negative and two positive" lens combination, enables the dynamic focusing module to achieve a wide range of adjustment of the equivalent focal length of the entire system within a short optical path space by only a small axial movement of the first lens, thereby quickly responding to and compensating for focus drift during the scanning process.

[0059] In some embodiments, the first lens is a meniscus negative lens, and the radius of curvature of the front surface of the first lens is -20mm to -30mm, and the radius of curvature of the rear surface is -40mm to -60mm. The second lens is a plano-convex positive lens, with a front surface curvature radius of 70mm~100mm and a rear surface being flat. The third lens is a plano-convex positive lens, with a front surface curvature radius of 200mm~260mm and a rear surface that is flat.

[0060] Specifically, the front surface refers to the side of the lens facing the incident laser beam, and the rear surface refers to the side of the lens facing away from the incident laser beam.

[0061] In this embodiment of the invention, the surface profile and radius of curvature parameters of each lens in the dynamic focusing module are specifically optimized to achieve a wide range of focal length compensation with a very small axial movement stroke, while strictly controlling aberrations.

[0062] The first lens, serving as a motion compensation element in the dynamic focusing module, primarily functions to diverge the laser beam and adjust the equivalent focal length of the system. The meniscus negative lens design effectively reduces spherical and coma aberrations introduced by the laser beam during lens movement. In this embodiment, the first lens is a meniscus negative lens with a front surface radius of curvature of -20mm to -30mm and a rear surface radius of curvature of -40mm to -60mm. This design not only ensures the lens has suitable optical power but also allows the system to achieve the required wide focal plane adjustment capability with minimal mechanical movement of the first lens. Simultaneously, this parameter range avoids the drastic increase in optical processing difficulty and sharp deterioration of edge aberrations caused by excessive curvature, and also avoids insufficient focal length adjustment sensitivity caused by excessively small curvature.

[0063] The second lens receives and converges the diverging beam from the first lens. In this embodiment of the invention, the second lens is a plano-convex positive lens with a front surface curvature radius of 70 mm to 100 mm and a rear surface that is flat. This plano-convex structure, with a convex front surface and a flat rear surface, results in a gentler deflection angle of the beam as it enters and exits the lens surface.

[0064] The third lens also adopts a plano-convex positive lens structure, which, together with the second lens, constitutes a positive optical power lens group. In this embodiment of the invention, the third lens is a plano-convex positive lens with a front surface radius of curvature of 200mm~260mm and a rear surface that is flat. Compared to using a single high-power positive lens, this embodiment of the invention shares the positive optical power of the system through the combination of the second and third lenses, which can significantly reduce higher-order aberrations generated during the transmission of large-aperture beams.

[0065] The radius of curvature of the front surface of the third lens is significantly larger than that of the second lens, meaning its optical power is relatively weaker. It is mainly used for beam shaping and fine correction of residual aberrations of the beam emitted from the second lens. The rear surface is set as a plane, which is conducive to the beam exiting in a better collimated or specific divergent state, matching the incident requirements of the subsequent mirror adjustment module and galvanometer module.

[0066] The dynamic focusing scanning galvanometer system provided in this invention, through a clever combination of meniscus and plano-convex surfaces and strict limitation of the curvature radius of each surface, perfectly balances the contradictions between "high response speed (short travel distance)," "large compensation range," and "high beam quality" without the need for F-Theta field lens assistance. When the laser beam scans the edge of the working plane at a large angle, this set of optimized lens parameters can suppress the focal point distortion caused by focal plane compensation to the greatest extent, ensuring a high degree of consistency in the energy distribution of the light spot throughout the forming area.

[0067] In some embodiments, the convex surfaces of the second lens and the third lens are both disposed facing the first lens.

[0068] Specifically, in this embodiment of the invention, the convex surfaces of both the second and third lenses face the first lens. In the optical path arrangement, the convex surfaces of these two plano-convex positive lenses face the first lens, which acts as the negative lens, while their flat surfaces face the beam emission direction. This specific lens orientation configuration is based on the optical design principles of minimum deviation angle and aberration balance. After the laser beam diverges to a certain extent after passing through the first lens (negative lens), the divergent beam sequentially enters the second and third lenses. By aligning the convex surfaces of the second and third lenses with the divergent beam, the incident and refraction angles of the light at the air-glass interface can be more uniformly distributed, avoiding excessive and abrupt deflection of the light on a single surface.

[0069] The dynamic focusing scanning galvanometer system provided in this embodiment of the invention significantly reduces spherical aberration when a large-aperture beam passes through by setting the convex surfaces of the second lens and the third lens towards the first lens, thereby further improving the beam quality that is finally focused on the working plane and enhancing the consistency of the beam forming quality.

[0070] In some embodiments, the materials of the first lens, the second lens, and the third lens have a refractive index of 1.46 and an Abelian coefficient of 67.8.

[0071] Specifically, in this embodiment of the invention, the refractive index of the materials of the first lens, the second lens, and the third lens are all configured to be 1.46, and their Abelian coefficients are all 67.8. The optical material having the above optical parameters is high-quality fused silica or other special optical glass with equivalent optical properties.

[0072] In laser powder bed fusion additive manufacturing, scanning galvanometer systems typically need to withstand high-energy laser beams with power in the kilowatt range or even higher, such as near-infrared lasers with a wavelength of 1064 nm. Choosing an optical material with a refractive index of 1.46 provides excellent high transmittance and low absorptivity when a mid-Gaussian beam passes through the lens, thereby minimizing laser energy loss within the optical components and ensuring the laser energy density reaching the working plane. Simultaneously, the high Abelian coefficient of 67.8 indicates that the material possesses extremely low dispersion characteristics. Although the system primarily uses single-wavelength lasers, the low-dispersion material effectively suppresses chromatic aberration caused by laser spectral broadening or minute wavelength drift, ensuring the optical path stability of the dynamic focusing module during adjustment.

[0073] Furthermore, optical materials with this refractive index and Abelian coefficient, such as fused silica, possess extremely low coefficients of thermal expansion. During long-duration, high-intensity continuous scanning printing, the lens is less prone to significant thermal expansion or localized refractive index gradient changes due to the absorption of minute amounts of laser energy. This significantly reduces the thermal lensing effect commonly found in high-power laser processing, ensuring the precision of equivalent focal length adjustment and maintaining a high degree of consistency in the quality and size of the focused spot across a large format.

[0074] The dynamic focusing scanning galvanometer system provided in this invention, through specific configuration of the material properties of the first, second, and third lenses, enables the dynamic focusing module to achieve a wide range of focal length adjustment while possessing excellent optical and thermal stability. This not only effectively reduces energy loss during high-power laser transmission but also significantly overcomes the thermal lensing effect and beam quality degradation problems that easily occur in high-energy laser scanning. This ensures the uniformity of spot energy distribution and long-term operational reliability in large-format continuous scanning printing, further improving the forming accuracy and equipment lifespan of the multi-beam full-coverage printhead.

[0075] In some embodiments, the deflection axis of the X-axis galvanometer and the deflection axis of the Y-axis galvanometer are spatially arranged to be perpendicular to each other.

[0076] Specifically, perpendicularity between opposite planes means that the deflection axes of the X-axis galvanometer and the Y-axis galvanometer do not intersect each other in three-dimensional space, and these two deflection axes are on the same projection plane, for example, the projection lines on a horizontal plane parallel to the working plane are perpendicular at 90 degrees.

[0077] Because the X-axis and Y-axis galvanometers have a certain volume in their physical structure, and the laser beam needs to be reflected sequentially by these two mirrors to achieve two-dimensional scanning of the plane, their deflection axes cannot be coplanar and intersecting in space. In this embodiment of the invention, the deflection axis of the X-axis galvanometer and the deflection axis of the Y-axis galvanometer are set to be perpendicular to each other in space.

[0078] The dynamic focusing scanning galvanometer system provided in this embodiment of the invention sets the deflection axis of the X-axis galvanometer and the deflection axis of the Y-axis galvanometer to be perpendicular to each other in space, which ensures precise orthogonal decoupling of the two-dimensional scanning trajectory in kinematics, and realizes two-dimensional scanning of the laser beam in the working plane.

[0079] In some embodiments, the maximum mechanical deflection angle of the X-axis galvanometer and the Y-axis galvanometer is not less than .

[0080] Specifically, the mechanical deflection angle of the galvanometer directly determines the optical scanning angle of the laser beam in space. According to the principle of optical reflection, the optical deflection angle of the laser beam is typically twice the mechanical deflection angle of the galvanometer. Therefore, when the maximum mechanical deflection angles of the X-axis and Y-axis galvanometers are not less than... At that time, the system can provide no less than The large optical deflection angle, combined with the relatively large working distance preset in the embodiments of the present invention, such as the approximately 750 mm gap between the Y-axis galvanometer and the working plane, allows the laser beam to be guided and projected onto a wider physical area on the working plane. For example, the deflection angle of the galvanometer at different scanning positions can cover... ,and Working status, etc.

[0081] In traditional scanning systems using F-Theta field lenses, forcibly increasing the deflection angle of the galvanometer to expand the scanning area will cause the laser beam to deviate too far from the optical axis at the center of the lens. This not only places extremely stringent requirements on the aperture of the F-Theta field lens, but also causes severe edge aberrations, resulting in larger and more distorted focused spot sizes at the edges of the scanning area, failing to meet the demands of high-precision printing.

[0082] This invention perfectly solves this technical bottleneck by abandoning the traditional F-Theta field mirror and instead adopting an architecture that combines a dynamic focusing module with a large deflection angle galvanometer. When the X-axis and Y-axis galvanometers are... When the laser oscillates over a wide range within the mechanical angle range of 360° and above, the spatial optical path of the laser reaching the working plane will undergo a significant nonlinear change, resulting in severe focal plane shift. In this situation, the system dynamically compensates for the large focal plane shift caused by the large deflection angle by adjusting the Z-axis position of the first lens in the dynamic focusing module in real time, thereby changing the system's equivalent focal length.

[0083] The dynamic focusing scanning galvanometer system provided in this embodiment of the invention employs a maximum mechanical deflection angle of not less than [missing information]. The galvanometer configuration allows the effective scanning range of a single laser beam on the working plane to easily break through traditional limits, achieving true single-beam large-format high-quality scanning. Each laser beam can easily achieve large-area overlap or full-width coverage, thereby greatly reducing or even completely eliminating boundary splicing defects caused by multi-area splicing scanning, and thus significantly improving the printing efficiency of laser additive manufacturing.

[0084] To further verify the optical compensation effect of the embodiments of the present invention, in a preferred embodiment, the system parameters are configured as follows: The first lens is a meniscus negative lens with a front surface curvature radius of -23.5 mm, a rear surface curvature radius of -50.3 mm, a center thickness of 2.0 mm, and a center-to-center distance of 55.4 mm between the first and second lenses.

[0085] The second lens is a plano-convex positive lens with a front surface curvature radius of 80.5 mm, a rear surface that is flat, a center thickness of 3.0 mm, and a center-to-center distance of 22.5 mm between the second and third lenses.

[0086] The third lens is a plano-convex positive lens with a front surface curvature radius of 230.0 mm, a rear surface that is flat, a center thickness of 2.4 mm, and a center-to-center distance of 20.0 mm between the third lens and the fixed reflector.

[0087] The materials of the first, second, and third lenses mentioned above all have a refractive index of 1.46 and an Abelian coefficient of 67.8.

[0088] In terms of the spatial arrangement of the optical path, the interval between the fixed reflector and the X-axis galvanometer is 20.0 mm; the interval between the X-axis galvanometer and the Y-axis galvanometer is 20.0 mm; and the interval between the Y-axis galvanometer and the working plane is approximately 750 mm.

[0089] Through the above optical simulation and system configuration, the point plots and energy distribution maps are compared with those without overall system configuration and those with overall system configuration. Figure 5 This is an optimized front view diagram of the dynamic focusing scanning galvanometer system provided by the present invention. Figure 6 This is an optimized dot plot of the dynamic focusing scanning galvanometer system provided by the present invention. Figure 7 This is one of the energy distribution diagrams before optimization of the dynamic focusing scanning galvanometer system provided by this invention. Figure 8 This is the second energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention before optimization. Figure 9 This is the third image of the energy distribution diagram before optimization of the dynamic focusing scanning galvanometer system provided by this invention. Figure 10 This is the fourth energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention before optimization. Figure 11This is the fifth image of the energy distribution diagram before optimization of the dynamic focusing scanning galvanometer system provided by this invention. Figure 12 This is one of the optimized energy distribution diagrams of the dynamic focusing scanning galvanometer system provided by this invention. Figure 13 This is the second optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention. Figure 14 This is the third optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention. Figure 15 This is the fourth optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention. Figure 16 This is the fifth optimized energy distribution diagram of the dynamic focusing scanning galvanometer system provided by this invention, as shown in Figure 5. Figures 7 to 16 As shown, after configuring the overall parameters according to the embodiments of the present invention, the focused spot diameter, focused spot roundness and energy concentration of the system within the large-format scanning range are significantly improved.

[0090] In this specific embodiment, the dynamic focusing scanning galvanometer system is suitable for near-infrared lasers with a wavelength of 1064 nm, and the system's entrance pupil diameter is 8.5 mm. With the above parameters, the effective scanning range of a single laser beam reaches 600 mm × 600 mm, and the focused spot size is strictly controlled to be less than [value missing] at any position within this ultra-large scanning range. The light spot consistency is good.

[0091] Based on the superior performance of the aforementioned dynamic focusing scanning galvanometer system, this embodiment of the invention also provides a multi-beam printhead. This multi-beam printhead includes multiple dynamic focusing scanning galvanometer systems as described above, arranged side-by-side to scan and cover the same forming plane.

[0092] In multi-beam collaborative operation, each dynamic focusing scanning galvanometer system operates as an independent and high-precision single-beam scanning unit. Each single-beam scanning unit eliminates the traditional and expensive large-aperture F-Theta field lens and independently compensates for Z-axis focal plane shift in real time through its own dynamic focusing module. Its effective single-beam scanning area and edge spot quality have been greatly improved. For example, a single beam can achieve high-quality scanning of 400 mm × 400 mm or even 600 mm × 600 mm.

[0093] It should be noted that the number and arrangement of the scanning galvanometer system in the multi-beam printhead, as well as the coverage relationship between each scanning area, can be adjusted according to the specific forming size and process requirements. This invention does not limit these aspects. Furthermore, the dynamic focusing module of the multi-beam printhead is configured to ensure that the corresponding laser beams achieve a consistent focused spot size and energy distribution within their respective scanning ranges, thereby improving the consistency and forming stability of multi-beam scanning. Each scanning galvanometer system independently compensates for focal plane shift caused by galvanometer deflection through its dynamic focusing module, ensuring that the corresponding laser beam can be stably focused on the forming plane within the full-coverage scanning range, thus guaranteeing that each laser beam has a consistent focused spot size and energy distribution throughout the entire forming area.

[0094] By arranging multiple such dynamic focusing scanning galvanometer systems in a spatial array, it is extremely convenient to achieve full-width coverage of ultra-large-sized powder beds, thereby significantly improving the printing efficiency and system scalability of multi-beam laser powder bed fusion molding while ensuring printing accuracy.

[0095] For example, the dynamic focusing scanning galvanometer system described in this invention is applied to a four-beam laser powder bed fusion printhead structure. This multi-beam printhead includes four scanning galvanometer systems, each with an identical structure. The four dynamic focusing scanning galvanometer systems are arranged side-by-side on the same forming plane. Each scanning galvanometer system corresponds to an independent laser beam, achieving full coverage within the forming plane to avoid the influence of scanning splicing boundaries on the forming quality. The full coverage area is 400 mm × 400 mm. Each scanning galvanometer system independently compensates for focal plane shift caused by galvanometer deflection through its dynamic focusing module, ensuring that the corresponding laser beam is stably focused on the forming plane within the full coverage scanning range. This guarantees that the four laser beams have a consistent focused spot size and energy distribution throughout the entire forming area.

[0096] In some embodiments, the scanning areas corresponding to adjacent dynamic focusing scanning galvanometer systems have overlapping coverage areas.

[0097] To address the quality issues that traditional multi-laser equipment often encounters during splicing printing, in this embodiment of the invention, adjacent dynamic focusing scanning galvanometer systems have overlapping or non-overlapping scanning areas to reduce or avoid splicing boundaries between multi-laser scanning areas.

[0098] Thanks to the advantages of the single-beam scanning galvanometer system, which can maintain an ultra-large effective scanning area (e.g., 600 mm × 600 mm) and highly consistent spot quality across the entire area even after removing the F-Theta field lens, this multi-beam printhead possesses extremely high freedom in scanning area allocation in practical process applications, mainly reflected in the following two collaborative working modes: First, the overlapping scanning mode for ultra-large components (reducing defects at splicing boundaries). When the size of a single large component to be formed exceeds the coverage limit of a single laser beam, the system configures the scanning areas of adjacent dynamic focusing scanning galvanometer systems to have a certain spatial overlap. Within this overlap area, the control system can flexibly schedule two or more adjacent laser beams, employing collaborative printing strategies such as cross-scanning, random staggered interlayer overlapping, or smooth energy density transition. This design completely breaks through the limitations of traditional multi-laser equipment performing "hard splicing" at fixed boundaries, effectively eliminating serious defects such as abrupt changes in energy density, incomplete fusion voids, and stress concentration at the interface. This enables multiple laser beams to achieve deep, seamless fusion at the metallurgical physics level, thereby greatly improving the overall mechanical properties and quality consistency of ultra-large components.

[0099] Second, the system employs a non-overlapping scanning mode for independent components. When multiple independent small to medium-sized components are being printed simultaneously in batches on the same large forming plane, and the size of each component can be completely covered independently by a single large-format laser beam, the system can configure adjacent dynamic focusing scanning galvanometer systems as independent working areas without overlap. In this mode, each independent laser beam is specifically responsible for forming one or more complete components within its corresponding area. This strategy fundamentally avoids the generation of splicing boundaries within any single component, ensuring the absolute continuity and uniformity of the microstructure within a single component. Simultaneously, the laser beams do not interfere with each other, maximizing the parallel processing efficiency and printing capacity of the multi-beam system.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamic focusing scanning galvanometer system, characterized in that, It includes a dynamic focusing module, a mirror adjustment module, and a galvanometer module arranged in sequence along the optical path transmission direction; The dynamic focusing module includes a first lens movably arranged along the optical axis direction, and a second lens and a third lens fixedly arranged, and is used for transmitting a laser beam; the laser beam sequentially passes through the first lens, the second lens, and the third lens along the optical path; the first lens is used to cause adjustment of the focusing position of the laser beam in the Z-axis direction; The mirror adjustment module includes at least one fixedly arranged mirror, and is used for reflecting the laser beam emitted from the dynamic focusing module and guiding it to the galvanometer module; The galvanometer module includes an X-axis galvanometer and a Y-axis galvanometer; both the X-axis galvanometer and the Y-axis galvanometer are plane mirrors; the X-axis galvanometer and the Y-axis galvanometer are used for sequentially receiving and deflecting the laser beam to achieve scanning of the laser beam within the working plane.

2. The dynamic focusing scanning galvanometer system according to claim 1, characterized in that, The galvanometer module is located at the outermost end of the optical path, and the laser beam emitted from the Y-axis galvanometer is directly focused on the working plane.

3. The dynamic focusing scanning galvanometer system according to claim 1, characterized in that, The first lens is a negative lens; the second lens is a positive lens; the third lens is a positive lens.

4. The dynamic focusing scanning galvanometer system according to claim 3, characterized in that, The first lens is a meniscus negative lens, and the radius of curvature of the front surface of the first lens is... The radius of curvature of the rear surface is ; The second lens is a plano-convex positive lens, and the radius of curvature of the front surface of the second lens is... The rear surface is flat; The third lens is a plano-convex positive lens, and the radius of curvature of the front surface of the third lens is... The back surface is flat.

5. The dynamic focusing scanning galvanometer system according to claim 3, characterized in that, The convex surfaces of the second lens and the third lens are both arranged facing the first lens.

6. The dynamic focusing scanning galvanometer system according to claim 4, characterized in that, The refractive index of the materials of the first lens, the second lens, and the third lens is 1.46, and the Abbe number is 67.

8.

7. The dynamic focusing scanning galvanometer system according to claim 1, characterized in that, The deflection axis of the X-axis galvanometer and the deflection axis of the Y-axis galvanometer are set to be skew perpendicular in space.

8. The dynamic focusing scanning galvanometer system according to claim 1, characterized in that, The maximum mechanical deflection angle of the X-axis galvanometer and the Y-axis galvanometer is not less than .

9. A multi-beam printhead, characterized in that, It includes a plurality of dynamic focusing galvanometer systems as described in any one of claims 1 to 8, and the plurality of dynamic focusing galvanometer systems are arranged side by side to jointly perform scanning coverage on the same forming plane.

10. The multi-beam printhead according to claim 9, characterized in that, There is an overlapping coverage area between the scanning areas corresponding to adjacent dynamic focusing galvanometer systems.

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