High-brightness light beam shaping system and laser processing head

Abstract

The utility model discloses a high-brightness light beam shaping system and a laser processing head, which are used for realizing transverse beam shrinkage of a laser beam by carrying out at least one refraction and linearity zooming on a collimated light beam so as to obtain the laser beam which can be directly used for processing. By adopting the shaping system, on one hand, the diameter of an original light beam is reduced, the quality of the light beam is improved, higher energy density and a better focusing effect are achieved, and it is guaranteed that the edge shape of the processed light beam is clear; and on the other hand, the processing cost of the prism for realizing refraction and linearity zooming is low, light beam shaping is realized only through the placing position and angle, and large-scale production and application are facilitated.

Description

Technical Field

[0001] This utility model relates to the field of laser processing, and in particular to a high-brightness beam shaping system and a laser processing head. Background Technology

[0002] In laser cutting, welding, drilling, and other processing operations, it is necessary to focus the laser beam into a very small spot to achieve high precision and efficiency. Focusing into a tiny spot also increases the power density of the laser at the focal point, enabling high-power processing. For example, for a 3kW fiber laser output through a 50µm fiber (NA=0.12), if the spot diameter can be reduced to half its original size, the power density at the focal point can be increased by 16 times.

[0003] Existing technologies typically employ lens-based beam-shrinking systems to shape the beam, using either a single aspherical lens or a collimating and focusing lens group. However, both of these methods struggle to achieve high image quality for the output beam, resulting in degraded energy distribution at the beam waist. Consequently, these optical systems produce lower beam brightness and negatively impact the cutting speed of thin plates. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a high-brightness beam shaping system and laser processing head to solve the technical problem that the output brightness of the existing optical system is low and the speed is slow when applied to thin plate cutting.

[0005] To achieve the above and other related objectives, this utility model provides a high-brightness beam shaping system and a laser processing head.

[0006] A high-brightness beam shaping system is disclosed. The beam shaping system achieves lateral beam contraction of the aligned straight beam by performing at least one refraction and linear scaling on the aligned straight beam, so as to obtain a laser beam that can be directly used for processing.

[0007] As a preferred embodiment, the beam shaping system includes at least one pair of right-angle prisms, which includes a first right-angle prism and a second right-angle prism arranged in a predetermined spatial position. The collimated beam enters from a right-angled facet of the first right-angle prism and exits from the inclined facet of the second right-angle prism.

[0008] As a preferred embodiment, the beam shaping system also includes a focusing mirror, which is positioned downstream of the right-angle prism pair along the light output direction to increase the distance between the intersection points where the annular beams are focused on the optical axis, thereby forming an axial multifocal beam.

[0009] As a preferred option, the focusing lens is a positive meniscus lens, and both the incident and exit surfaces of the focusing lens are spherical.

[0010] As a preferred option, the radius of curvature of the incident surface of the focusing lens is greater than the radius of curvature of the exit surface of the focusing lens.

[0011] As a preferred option, the energy distribution of the collimated beam is homogenized in the far field along the optical axis.

[0012] As a preferred option, the beam waist diameter of the beam emitted from the focusing lens is less than 0.5 mm.

[0013] As another aspect of this application, this application also proposes a high-brightness laser processing head that employs the beam shaping system of any of the above-described schemes.

[0014] As described above, this utility model provides a high-brightness beam shaping system and laser processing head. This beam shaping system achieves lateral beam contraction of the laser beam by performing at least one refraction and linear scaling on a straight beam, thereby obtaining a laser beam directly usable for processing. Using the shaping system of this application, on the one hand, it helps to reduce the diameter of the original beam, improve beam quality, achieve higher energy density and better focusing effect, and ensure that the edge shape of the processed beam is clear; on the other hand, the prisms used to achieve refraction and linear scaling have low processing costs, and beam shaping is achieved simply by adjusting their placement and angle, making it more suitable for large-scale production applications. Attached Figure Description

[0015] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0016] Figure 1 This is a schematic diagram of the laser focusing position in existing processing technologies;

[0017] Figure 2 This is a schematic diagram of the optical path structure in one embodiment of this application;

[0018] Figure 3 Is adopted Figure 2 A schematic diagram showing the effect achievable after the optical path structure is implemented;

[0019] Figure 4 This is a schematic diagram of the plano-concave conical lens provided in this embodiment;

[0020] Figure 5 This is a schematic diagram of the plano-convex conical lens provided in this embodiment;

[0021] Figure 6 This is a schematic diagram of the optical path structure before the improvement.

[0022] Figure 7 Is adopted Figure 6 A schematic diagram illustrating the effect achieved by the optical path structure.

[0023] Figure 8 This is a schematic diagram of the optical path structure in another embodiment of this application;

[0024] Figure 9 This is a schematic diagram of the optical path structure in another embodiment of this application;

[0025] Figure 10 This is a schematic diagram illustrating the principle of using a prism to align direct light to achieve lateral beam contraction in the embodiments of this application. Detailed Implementation

[0026] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as "electrically connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "upper," "lower," "inner," "outer," "bottom," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0028] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Existing laser processing heads have small focused beam spot diameters and limited focal depths. On the one hand, this can easily lead to thinner cuts / welds when used to process medium-thick metal plates, resulting in low laser energy utilization and poor slag removal. On the other hand, even if the laser penetrates the plate, the material removal at the bottom of the plate is inconsistent, with a large amount of molten slag adhering and poor cut / weld quality.

[0030] To address the issue of poor processing quality in medium-thick plate applications, the focus position of the output laser is typically adjusted to achieve the same processing effect in medium-thick plate processing as it does in thin plate processing. Specifically, in cutting applications, the focus position of the output beam is adjusted mechanically by adjusting the height of the processing head. However, the nozzle height H (defined in the industry as the distance between the nozzle bottom and the surface to be cut) has a limited adjustment range, constrained by the airflow parameters of the nozzle output. To ensure airflow, the relative height H between the nozzle and the workpiece surface has a small adjustment range (typically 2mm-5mm). Since the thickness of medium-thick plates is typically greater than 4.5mm, existing technologies that change the height of the processing head by translation and further adjust the focus position cannot meet all processing requirements. In other solutions, a beam shaping system can be designed into the laser processing head. By adjusting the optical axis spacing of the internal mirror groups, a zoom function can be achieved, allowing the laser focus position to be adjusted axially. Based on the axially adjustable focus position function, subsequent technologies have been developed for negative defocus cutting of materials such as stainless steel and positive defocus cutting of materials such as carbon steel.

[0031] For example, such as Figure 1 Image (1a) shows a schematic diagram of the laser focusing position during negative defocusing of the laser processing head (only the nozzle portion is shown), as follows: Figure 1 Image (1b) shows a schematic diagram of the laser focusing position when the laser processing head (only the nozzle portion is shown) is in focus. Figure 1 (1c) shows a schematic diagram of the laser focusing position when the laser processing head (only the nozzle part is shown) is in a defocusing operation.

[0032] Combination Figure 1 In (1a), (1b), and (1c), the nozzle height H of the laser processing head is relatively small. During cutting operations, a large amount of dust and smoke is generated. These impurities adhere to the protective lens (not shown) of the laser processing head, which easily leads to power attenuation and heat loss in the optical path. An excessively small nozzle height H significantly increases the probability of these impurities entering the nozzle and the interior of the processing head. Furthermore, due to the small nozzle height, when facing complex surfaces, the nozzle is limited by its spatial position and cannot reach the intended position for operation, resulting in poor cutting effects. Additionally, the low workpiece flatness easily leads to collisions, which is detrimental to mass production. Figure 1 As shown in (1c) and (1d), by increasing the nozzle height H, the probability of impurity adhesion can be reduced, the reliability of laser processing can be improved, the replacement frequency of consumable parts can be reduced, and the adaptability to complex surface cutting can be improved.

[0033] However, when the nozzle height is increased, such as Figure 1As shown in (1a), when the laser beam is in negative defocus operation, the beam waist radius is located below the surface of the material to be processed. Due to laser divergence, when the negative defocus of the laser beam is too large, the beam at the edge of the laser beam will be blocked by the nozzle. Although most of the laser beam energy is concentrated in the axis of the beam, the laser used to process medium and thick plates is a high-power laser (usually above 5 kW). The edge beam will still cause the nozzle temperature to continue to increase until the temperature is too high and the laser cutting system stops. This affects the stability of the laser processing head and the availability of the equipment. When the nozzle height is raised, such as... Figure 1 As shown in (1e), in order to prevent the edge of the laser beam from being blocked by the nozzle, the negative defocusing depth of the laser beam is actually reduced, resulting in poor negative defocusing cutting effect of the laser processing head, or even the inability to perform negative defocusing operations.

[0034] To overcome the shortcomings of the prior art, embodiments of the present invention provide a beam shaping system for improving the energy utilization rate of laser beams in laser processing. In one embodiment, the beam shaping system includes, in sequence along the laser transmission direction: a collimating lens 11, a beam shaper 12, and a focusing lens 13, i.e. Figure 2 As shown.

[0035] The collimating lens 11 is used to collimate the laser beam output by the laser; the beam shaper 12 is a conical lens or a spherical mirror, used to expand the aperture angle of the collimated beam before it is incident on the focusing lens 13, and to increase the incident height of the collimated beam; the focusing lens 13 is used to converge the annular light with different incident heights in the laser beam to different positions along the optical axis, forming an axial multifocal beam.

[0036] In the embodiments of this application, the energy distribution of the collimated beam is homogenized along the optical axis in the far-field direction.

[0037] When Figure 2 When the optical path structure shown is applied to cutting, its effect is as follows: Figure 3 As shown, the light spot formed at the positive focal position is ring-shaped, while the light spot formed at the negative focal position maintains a circular shape. The diameter of the light spot at the beam waist is larger than that without adding a beam shaper, the beam divergence angle is reduced, and the size of the light spot changes relatively slowly along the optical axis, which helps to reduce the sensitivity of the cutting process to the focal point.

[0038] Optionally, the beam shaping system also includes a driving unit connected to the collimating lens 11. This driving unit drives the collimating lens 11 to move along the optical axis to adjust the energy distribution of the collimated beam, making the energy of the collimated beam more uniform along the optical axis, thereby improving the axial utilization of the collimated beam. Optionally, the driving unit can be a vibration motor. It is understood that by driving the collimating lens to move along the optical axis, energy can be uniformly distributed along a certain segment of the optical axis, achieving a long depth-of-field optical energy state, thus enabling high-speed cutting.

[0039] In this embodiment, the incident height of the laser beam is raised by the beam shaper 12, and the focusing lens 13 is further configured in reverse curvature to disperse the laser beam at the focusing position on the optical axis. That is, aberrations are used to focus the beam at different positions on the optical axis, with a certain distance between each focusing position. The resulting axial multifocal beam is not affected by the raised nozzle design during processing, which can meet the defocusing requirements of the laser processing head and effectively prevent metal spatter and reflected light generated during processing from entering the nozzle, causing internal blockage and optical path damage. At the same time, this application also drives the collimating lens 11 to vibrate along the optical axis at a predetermined frequency through the driving unit to adjust the energy distribution of the collimated beam, so that the energy of the collimated beam is uniformly distributed along the optical axis, thereby improving the axial utilization rate of the collimated beam.

[0040] In existing technologies, the focused beam output from conventional laser processing heads typically has a small spot diameter and limited focal depth. When applied to cutting medium-thick metal plates, the small spot diameter results in a narrow kerf, which is detrimental to slag removal. Even if the laser penetrates the plate, uneven material removal at the bottom leads to a large amount of molten slag adhering to the surface, resulting in poor cut quality. To address this issue of poor quality in medium-thick plate cutting, the focusing position of the output laser is usually adjusted to achieve the same processing effect as cutting thin plates. However, the nozzle height H of the laser processing head has a limited adjustment range. The focusing position can be adjusted mechanically by adjusting the head height H. This adjustment range is limited by the airflow rate parameter of the nozzle output. To ensure the airflow rate, the relative height H between the nozzle and the surface to be processed has a small adjustment range (H is typically 2mm-5mm; the industry defines the distance between the bottom of the nozzle and the surface to be cut as the nozzle height H), making it only suitable for welding thin plates with a thickness between 0.5mm and 4mm. The thickness of medium-thick plates is usually greater than 4.5mm, which causes the overall height of the machining head to change by translating the machining head, and further changes the focusing position, which cannot meet the actual application requirements.

[0041] like Figure 6As shown, a conventional laser processing head only has a collimating lens 11 and a focusing lens 13, and the collimating lens is usually fixed. The collimated beam exits from the collimating lens 11 and enters the incident surface of the focusing lens 13 at the same incident height and a 0° aperture angle. To reduce the optical medium surface area of ​​the beam shaping system and simplify system design, the focusing lens 13 is typically a biconvex lens used to converge the beam. Curvature correction is employed in the design of the focusing lens 13 to minimize aberrations in the optical path system, ensuring that the laser beam is converged to the same position on the optical axis as much as possible.

[0042] Adopting such Figure 6 The laser processing head with the optical path structure shown has circular light spots at both the positive and negative focal points, a small spot diameter at the waist, and a short optical path for processing. Figure 7 As shown.

[0043] In embodiments of the present invention, a beam shaper 12 is added between the collimating lens 11 and the focusing lens 13. Combined with the collimating lens vibrating at a predetermined frequency along the optical axis, the direction of the collimated beam is changed. Simultaneously, after exiting the beam shaper 12, the beam enters the focusing lens 13 at a certain aperture angle, and the incident height of the beam is increased, resulting in a larger spot area of ​​the collimated beam entering the focusing lens 13. That is, the beam, which would otherwise have a paraxial region entering the focusing lens 13, is instead entered from a relatively far-axial region. The driving unit drives the collimating lens to vibrate, adjusting the vibration frequency of the collimated beam. This allows the laser energy to be uniformly distributed in a specific area per unit time, thereby achieving uniform heating of the molten pool formed on the workpiece surface, which helps reduce spatter generated during processing.

[0044] It should be noted that, for the focusing lens 13 (spherical lens) used to achieve the converging effect in this invention, the image-side intercept of the beam incident from the far-axis region is smaller than that of the beam incident from the paraxial region. Therefore, the convergence point of the beam incident from the far-axis region on the optical axis will be closer to the exit surface of the focusing lens 13 than that of the beam incident from the paraxial region. Based on the above principle, the beam shaper 12 is set to make the spot area of ​​the collimated beam larger, which makes the beam incident on the focusing lens from a higher incident height, and ultimately the focusing position of the laser beam on the optical axis is more dispersed, and the beam has multiple focusing positions on the optical axis.

[0045] In this embodiment, to cooperate with the beam shaper 12, the focusing lens 13 is a biconvex spherical lens to minimize the cost of the optical path system. Furthermore, in its design, it utilizes a reverse curvature matching method to increase the aberration of the focusing lens (adjusting the curvature ratio of the incident and exit surfaces of the focusing lens to increase aberration). This results in a greater distance between the focusing positions of the beam incident from the far-axis region and the focusing positions of the beam incident from the paraxial region, further dispersing the laser beam's focusing positions on the optical axis and widening the spacing between each focusing position. Through the cooperation of the conical lens and the focusing lens, such as... Figure 1 and Figure 2 As shown, D3 > L3, D2 > L2, D1 > L1. The increased spacing between each focusing position (F0, F1, F2, F3) on the optical axis increases the depth of focus (DOF) of the formed beam, which can meet the requirements of negative defocusing operations while ensuring that the edge of the beam is not obstructed by the raised nozzle.

[0046] Additionally, it should be noted that in high-power laser cutting of medium and thick plates, the laser beam formed by a conventional zoom system is a Gaussian beam. The energy density at the focal point of the laser beam is too high, which can easily cause hole bursts and is not conducive to slag removal. Therefore, laser cutting is usually performed at a position with a slightly larger spot diameter. In actual processing applications, each plate thickness and each material has its own relatively suitable spot size.

[0047] Using the method provided in this embodiment, such as Figure 2 The beam shaping system shown shifts the energy of its beam waist to the negative defocus direction, improving negative defocus cutting efficiency. Furthermore, the beam spot diameters acting on the material differ less, resulting in minimal energy density variation and preventing a stepped cut, thus reducing porosity. In contrast, [the system also exhibits better performance in comparison]. Figure 1 and Figure 2 Due to the limitations imposed by the cutting process on the spot size, when the same spot size is applied to the material surface, Figure 2 The resulting cutting beam is relative Figure 1 The resulting cutting beam requires a deeper negative defocus depth to meet the operational requirements. A relatively deeper defocus depth (without changing the nozzle height) will result in higher beam energy acting on the nozzle, which will not only cause the nozzle to get hot, but also reduce the energy utilization rate. Figure 1 The resulting cutting beam is relative Figure 2 The resulting cutting beam can meet the spot size requirements by adjusting the defocus depth of the beam within a small depth range. At the same time, the divergence angle of the beam segment acting inside the material is small, and the spot size changes at a low rate. When the lens experiences temperature drift, the consistency of the cutting section will not be affected by the temperature drift.

[0048] As one example, such as Figure 4As shown, the beam shaper 12 uses a plano-concave conical lens, with its concave surface serving as the incident surface. The cone angle of the concave surface is between 0.5° and 3°. Furthermore, in order to prevent the incident surface from forming a sharp surface, the paraxial region of the plano-concave conical lens is set as a smooth curved surface, such as a smooth spherical surface that is smoothly connected to the conical surface, in order to avoid heat concentration. When a plano-concave conical lens is used and the focusing lens is designed with reverse curvature, the incident beam converges at different positions on the optical axis due to different incident heights.

[0049] As another example, beam shaper 12 employs Figure 4 The plano-concave conical lens shown has a concave cone angle between 0.5° and 3°, but its flat surface serves as the incident surface and its concave surface serves as the exit surface. Furthermore, the paraxial region of the plano-concave conical lens is set as a smooth curved surface, which can also raise the incident height of the collimated beam. Combined with a focusing lens with a reverse curvature design, it forms a multifocal beam.

[0050] As another example, such as Figure 5 As shown, the beam shaper 12 uses a plano-convex conical lens, with its flat surface as the incident surface and its convex surface as the exit surface. The cone angle of the convex surface is between 0.5° and 3°, and the paraxial region of the plano-convex conical lens is set as a smooth curved surface, which can also raise the incident height of the collimated beam. Combined with the focusing lens with a reverse curvature design, it forms a multifocal beam. When using a plano-convex conical lens, sufficient space needs to be reserved between the conical lens and the focusing lens, making it longer than the beam shaping system using a plano-concave conical lens.

[0051] As another example, such as Figure 5 As shown, the beam shaper 12 uses a plano-convex conical lens, with its convex surface as the incident surface and its flat surface as the exit surface. The cone angle of the convex surface is between 0.5° and 3°, and the paraxial region of the plano-convex conical lens is set as a smooth curved surface, which can also raise the incident height of the collimated beam. Combined with the focusing lens with the reverse curvature design, a multifocal beam is formed.

[0052] As another embodiment of this application, please refer to Figure 8 and Figure 9 Its optical path structure includes: a beam shaper 12 and a focusing lens 13; wherein, the beam shaper 12 is used to receive the diverging laser and convert the diverging laser into a collimated beam that is parallel to the output, that is, the laser emitted by the collimating lens can be approximated as a collimated beam, and it is also used to amplify the spherical aberration of the optical path system; the focusing lens 13 is used to converge the collimated beam to the optical axis to form a focused beam, and it is also used to increase the aperture of the optical path system to form an axial multifocal beam.

[0053] As an example, such as Figure 8As shown, the beam shaper 12 employs a biconvex lens, and the focusing lens 13 also employs a biconvex lens. Furthermore, in the beam shaper 12, the surface with the smaller radius of curvature faces the collimating beam, and the surface with the larger radius of curvature faces the diverging beam. In the focusing lens 13, the surface with the smaller radius of curvature faces the collimating beam, and the surface with the larger radius of curvature faces the converging beam, to minimize spherical aberration. Each lens employs... Figure 8 The ratio of the curvature radii of the structure shown can converge the resulting focused beam to the same position on the optical axis as much as possible. However, due to the use of spherical lenses, the spherical aberration of the system can only be corrected and reduced as much as possible, but cannot be completely eliminated. Figure 8 As shown, beams of different annular zones (different incident heights) are focused at different axial focusing positions on the optical axis (the focusing position is the intersection of the beams of different annular zones with the optical axis after they converge).

[0054] As an example, such as Figure 9 As shown, the beam shaper 12 uses a biconvex lens, with the smaller radius of curvature facing the diverging beam and the larger radius of curvature facing the collimating beam. That is, the beam shaper 12 uses reverse curvature, making the radius of curvature of the incident surface greater than that of the exit surface, thereby increasing spherical aberration while satisfying the collimation function. The focusing lens 13 uses a spherical meniscus lens, with the smaller radius of curvature facing the collimating beam and the larger radius of curvature facing the converging beam. That is, it uses a positive meniscus lens. The positive meniscus lens can increase the system NA of the optical path structure. The larger the NA, the greater the spherical aberration, which can increase the distance between the axial focusing positions of different annular zones on the optical axis. It should be noted that the collimated beam formed by the collimating lens 11 provided in this embodiment is a weakly collimated beam, which is not a strictly parallel beam. While meeting the magnification design requirements, it also undertakes the design function of increasing spherical aberration. Therefore, in the output beam, the beam of the edge ring (far axis) will form a certain angle with the optical axis relative to the beam of the paraxial ring. This results in the beam emitted from the edge of the collimating lens 11 having a higher incident height when it enters the focusing lens 13. The increased incident height can increase the distance between the axial focusing positions.

[0055] Through the cooperation of collimating lens 11 and focusing lens 13, such as Figure 8 and Figure 9As shown, D3 > L3, D2 > L2, and D1 > L1. The increased spacing between the focal positions (F0, F1, F2, F3) on the optical axis increases the depth of focus (DOF) of the formed beam. This satisfies the requirements for negative defocusing operations while ensuring the beam edge is not obstructed by the raised nozzle. It should also be noted that in high-power laser cutting of medium-thick plates, the laser beam formed by a conventional zoom system is a Gaussian beam. The energy density at the focal point is too high, which can easily cause hole bursts and hinder slag removal. Therefore, laser cutting is typically performed at a position with a slightly larger spot diameter. In actual processing applications, each plate thickness and each material has its own relatively suitable spot size.

[0056] In contrast, adopting such Figure 8 The Y1 segment shown in the diagram cuts into the material. Because the plate thickness is greater than the focal depth, the spot diameter within the Y1 segment increases synchronously with the laser beam divergence angle in a certain proportion. The spot size changes rapidly, resulting in significant energy density variations. The kerf is stepped, and most of the cutting waste accumulates and cannot be discharged, preventing normal perforation. In some cases, it can even cause bursts, returning the waste to the original optical path, puncturing the protective lens, and damaging the processing head. Using the method provided in this embodiment... Figure 2 The laser processing head with the optical path structure shown shifts the energy of its beam waist to the negative defocus direction, improving the negative defocus cutting efficiency. Furthermore, the difference in the spot diameter of the beam acting on the material is small, resulting in minimal energy density variation. This avoids a stepped cut surface and helps reduce porosity. In comparison... Figure 8 and Figure 9 Due to the limitations imposed by the cutting process on the spot size, when the same spot size is applied to the material surface, Figure 8 The resulting cutting beam is relative Figure 9 The resulting cutting beam requires a deeper negative defocus depth to meet the operational requirements. A relatively deeper defocus depth (without changing the nozzle height) will result in higher beam energy acting on the nozzle, which will not only cause the nozzle to get hot, but also reduce the energy utilization rate.

[0057] Understandable. Figure 9 The resulting cutting beam is relative Figure 8 The resulting cutting beam can meet the spot size requirements by adjusting the defocus depth of the beam within a small depth range. At the same time, the divergence angle of the beam segment acting inside the material is small, and the spot size changes at a low rate. When the lens experiences temperature drift, the consistency of the cutting section will not be affected by the temperature drift.

[0058] Optional, Figure 9 The resulting focused beam has a beam waist diameter greater than 0.5 mm, while Figure 8The diameter of the focused beam waist is usually less than 0.1 mm. While a larger beam waist diameter is not suitable for fine cutting of thin plates, it can be adapted to the cutting of medium and thick plates. Furthermore, due to the low rate of change of the beam size, the cut surface has good consistency.

[0059] In this application, a prism can also be used to refract and linearly scale the 10-aligned straight beam at least once to achieve lateral beam contraction of the laser beam. The principle of using a prism to achieve lateral beam contraction of the 10-aligned straight beam is as follows: Figure 10 As shown, this principle has been demonstrated in "Design of Shaping Prisms for Semiconductor Laser Systems" (Zhang Ping, 1990 note), and therefore will not be repeated in this application.

[0060] A first right-angle prism 101 and a second right-angle prism 102 are arranged in a predetermined spatial position in the optical path. The collimated beam emitted from the collimating lens 11 enters from a right-angled surface of the first right-angle prism and exits from the inclined surface of the second right-angle prism. This helps to reduce the beam diameter at the beam waist, achieves higher energy density and better focusing effect, and ensures that the edge shape of the processed beam is clear.

[0061] It should be noted that the collimating lens mentioned in this embodiment should be understood as a lens group used to achieve the collimation function. Its collimation function can be achieved by a single lens or by multiple lenses working together. In the beam shaping system of the laser processing head, multiple protective lenses can be added to achieve sealed protection of the collimating lens and the focusing lens. A beam splitter can be added to achieve process monitoring of laser processing. To avoid redundancy, these lenses are not shown in the structure of the laser processing head in this application. In practical applications, these lenses can be selected.

[0062] In addition, to improve the focusing effect of the beam output by the beam shaping system, the beam shaping system also includes at least one pair of right-angle prisms. The pair of right-angle prisms is disposed between the beam shaper and the focusing lens, and the three are connected in the optical path. The pair of right-angle prisms is used to perform beam shaping on the beam output from the beam shaper.

[0063] like Figure 10 As shown, a first right-angle prism 101 and a second right-angle prism 102 are arranged in the optical path according to a predetermined spatial position. The collimated beam emitted from the collimating lens 11 enters from a right-angled surface of the first right-angle prism and exits from the inclined surface of the second right-angle prism. This helps to reduce the beam diameter at the beam waist, achieves higher energy density and better focusing effect, and ensures that the edge shape of the processed beam is clear.

[0064] It can be understood that when the right-angle prism pair is configured such that a first collimated beam with a circular cross-section exits from the right-angle prism pair, a second collimated beam with an elliptical cross-section is formed (that is, the beam is compressed in one direction while remaining unchanged in the other direction). By utilizing the refraction effect of the prisms and the linear scaling effect on the collimated laser beam, the collimated beam is shaped and compressed.

[0065] In some embodiments, when the right-angle prism pair is configured as two (adding another prism group to the aforementioned right-angle prism pair) and arranged in a certain spatial position, a third collimated beam with a smaller cross-sectional area than the first collimated beam can be formed (achieving beam compression in two mutually perpendicular directions). The cross-section of the third collimated beam is also circular. In this embodiment, the first right-angle prism pair causes the beam to change in the XY direction, and the second right-angle prism pair causes the beam to change in the XZ direction. The principle of using prism pair 10 to achieve lateral beam contraction of collimated light has been shown in "Design of Shaping Prisms for Semiconductor Laser Systems" (Zhang Ping, 1990 note), and therefore will not be repeated in this application.

[0066] As a preferred solution, when the aligned straight beam undergoes two refractions and linear scaling, the lateral beam contraction of the aligned straight beam can be achieved, and the beam waist diameter of the beam emitted from the focusing lens is less than 0.5 mm.

[0067] As another aspect of this application, a high-brightness laser processing head is also proposed, which employs the beam shaping system described in any of the above-mentioned schemes.

[0068] In summary, the high-brightness beam shaping system and laser processing head described in this application achieve lateral beam contraction of the laser beam by performing at least one refraction and linear scaling on a straight beam, thereby obtaining a laser beam that can be directly used for processing. Using the shaping system of this application has advantages in two aspects: firstly, it helps to reduce the diameter of the original beam, improve beam quality, achieve higher energy density and better focusing effect, and ensure that the edge shape of the processed beam is clear; secondly, the prisms used to achieve refraction and linear scaling have low manufacturing costs, and beam shaping is achieved simply by adjusting their position and angle, making it more suitable for large-scale production applications.

[0069] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A high-brightness beam shaping system, characterized in that, The beam shaping system includes a focusing lens and at least one pair of right-angle prisms. The pair of right-angle prisms includes a first right-angle prism and a second right-angle prism. The collimated beam enters from a right-angled facet of the first right-angle prism and exits from the inclined facet of the second right-angle prism. The focusing lens is positioned downstream of the pair of right-angle prisms along the light output direction to increase the distance between the focal points of each annular beam focused on the optical axis, thereby forming an axial multifocal beam. The focusing lens is a positive meniscus lens, and both its incident and exit surfaces are spherical. The beam shaping system achieves lateral beam contraction of the collimated beam by performing at least one refraction and linear scaling on the collimated beam to obtain a laser beam that can be directly used for processing.

2. The beam shaping system according to claim 1, characterized in that, The radius of curvature of the incident surface of the focusing lens is greater than the radius of curvature of the exit surface of the focusing lens.

3. The beam shaping system according to claim 1, characterized in that, The energy distribution of the collimated beam is homogenized in the far field along the optical axis.

4. The beam shaping system according to claim 1, characterized in that, The beam waist diameter of the beam emitted from the focusing lens is less than 0.5 mm.

5. A high-brightness laser processing head, characterized in that, The beam shaping system described in any one of claims 1-4 is employed.

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