Dynamic zoom and focus of laser processing apparatus

Abstract

The present invention relates to a laser processing device (10) comprising an optical system having: a beam width adjustment optical group (20) for adjusting the beam width of a laser beam (B); and a focusing optical group (30) having an adjustable focal length, in which the focusing optical group (30) is arranged along the beam path of the laser beam (B) between the beam width adjusting optical group (20) and the laser output (14); wherein the optical system is configured to adjust a focal position of the laser beam and a spot size corresponding to a beam width of the laser beam at the focal position (F). The beam width adjusting optical group (20) is configured to change the absolute value of the beam propagation angle of the laser beam (B) by no more than 10 DEG; and / or such that a ratio of a distance from the beam width adjusting optical system to the focusing optical system along an optical path of the laser beam to a Rayleigh length of the laser beam measured downstream of the beam width adjusting optical group is not greater than 60. The invention also relates to an associated method of operating a laser machining device (10) for laser machining a workpiece (P).

Description

Technical Field

[0001] This invention relates to the field of laser processing, and specifically to laser processing apparatus and related methods. Background Technology

[0002] In the field of laser processing, laser beams are commonly used for a variety of applications, including cutting, welding, engraving, and additive manufacturing. Known systems typically involve using optical components to guide and focus the laser beam onto the workpiece. These systems often require manual adjustments to change the beam width or focal position, which can be time-consuming and error-prone. Furthermore, integrating multiple laser beams with different characteristics (such as different wavelengths, beam intensity distributions, or beam shapes) into a single processing unit presents significant challenges in terms of alignment and control.

[0003] According to known methods, laser processing systems often lack the ability to simultaneously and / or independently adjust the focal position and its corresponding spot size in real time, with the latter typically limited by the former. This limitation can lead to suboptimal processing conditions, resulting in reduced accuracy and efficiency. For example, in laser welding or cutting processes, the inability to fine-tune beam parameters in real time can lead to defects in the workpiece or inefficient material removal. Furthermore, existing systems may struggle to maintain consistent beam quality when switching between different operating modes or when processing materials with different properties.

[0004] Despite significant advancements in laser processing, there remains a need for improved systems that offer better control over laser beam parameters. Specifically, a device is required that can seamlessly adjust beam width and focal position without human intervention, thereby enhancing processing accuracy and efficiency. Additionally, systems capable of handling multiple laser beams with varying characteristics are needed to ensure precise alignment and optimal performance across a wide range of applications.

[0005] EP 3838472A1 discloses a laser processing apparatus capable of adjusting the spot size or beam width of a laser beam while maintaining a constant focal position. For this purpose, the laser processing apparatus includes a focusing device having at least two movable lenses and possibly at least one fixed lens. A disadvantage of this laser processing apparatus is that, for example, for a collimated laser beam, the maximum beam width allowed to enter the apparatus is limited, and therefore the increase in the maximum beam width achievable using this laser processing apparatus while maintaining a constant focal position is also limited. Therefore, optimal use of this apparatus may require a strongly divergent input laser beam, which, at least under optimal operating conditions, precludes the use of one or more collimated laser sources. Consequently, this laser processing apparatus has limited compatibility with the use of beam conditioning elements, such as beam shapers, e.g., diffractive optical elements.

[0006] US2005 / 0150876A1 discloses a laser welding robot including devices for focusing and directing a laser beam. The devices include a first optical group and a second optical group, wherein the first optical group includes a first axially movable lens configured to collimate a diverging input laser beam, and the second optical group includes a movable lens for converting the collimated beam into a diverging beam focused by a fixed focusing module. Coordinated control of the axial positions of the movable lenses of the first and second optical groups allows for adaptation of the focusing distance of the laser beam on the structure to be welded.

[0007] Therefore, the technical problem of the present invention is to provide a laser processing apparatus that at least partially overcomes the shortcomings of known systems. Summary of the Invention

[0008] The object of the present invention is to provide a laser processing apparatus and related method that overcomes one or more of the disadvantages of previously described known systems, specifically by providing a more precise and dynamic way to adjust the focal position and beam width (particularly the spot size) of the processing laser beam, while offering maximum flexibility in the laser beam conditions input to the apparatus. This is achieved by the laser processing apparatus according to claim 1 and the method according to claim 11. Preferred embodiments of the invention are defined in the appended dependent claims.

[0009] A first aspect of the invention relates to a laser processing apparatus as defined in claim 1, which can be configured to perform laser processing on a workpiece, wherein laser processing as used herein can refer to any process in which a laser is used to alter the properties of a workpiece or material, including, for example, 3D printing, welding, cutting, marking, engraving, etc. The laser processing apparatus is specifically adapted to laser process workpieces in a laser powder bed fusion process, or to weld parts in a laser welding process, specifically adapted to weld battery cells and / or adapted to weld bipolar plates for combustible cells.

[0010] The laser processing apparatus includes a laser input section for receiving a laser beam (optionally a collimated laser beam) and a laser output section for outputting the laser beam. The laser input section may include one or more of a glass window, an aperture, and a fiber optic connector, and may include a collimation system (e.g., one or more collimating lenses). In a preferred embodiment, the laser input section may not have any fiber optic connectors and / or may be preferably configured as an aperture, which allows the input of a laser beam with any beam shape. The laser output section may include one or more glass windows and / or one or more apertures. The laser processing apparatus may include a housing surrounding other components of the laser processing apparatus, which may encompass all of these components, and the laser input section and laser output section may be formed through the housing.

[0011] The laser input section can be configured to receive a collimated laser beam for inputting the collimated laser beam into a laser processing apparatus. Therefore, the laser input section may lack any focusing lens and / or any collimating optics system, unlike other types of laser input sections typically used to receive diverging or converging laser beams. The laser input section can have an aperture ranging from 5 mm to 50 mm.

[0012] A laser beam is input into the laser processing apparatus via a laser input section and output from the laser processing apparatus via a laser output section. Therefore, the beam path of the laser beam is limited within the laser processing apparatus between the laser input section and the laser output section. More than one laser beam can also be input into the laser processing apparatus via corresponding laser input sections. The laser beams can then co-propagate and / or overlap within the laser processing apparatus and can all be output via the laser output section.

[0013] The laser processing apparatus includes an optical system that defines a laser beam between a laser input section and a laser output section. Therefore, the laser beam is transmitted between the laser input section and the laser output section through this optical system.

[0014] The optical system of the laser processing apparatus includes a beam width adjustment optics group and a focusing optics group. The beam width adjustment optics group is configured to adjust the beam width of the laser beam.

[0015] A beam width adjustment optics group can adjust the beam width of a laser beam while maintaining its collimation substantially constant. "Collimation" herein refers to the collimation state of the laser beam input to the optical system via the laser input section, which is substantially unaffected by the beam width adjustment optics group and specifically can be kept constant. When the laser beam enters the beam width adjustment optics group, the laser beam can be collimated, slightly divergent, or slightly convergent. Maintaining the collimation of the laser beam means that when leaving the laser beam width adjustment optics group, the laser beam can also be collimated, slightly convergent, or slightly divergent, respectively. It is possible that the beam width adjustment optics group can maintain constant laser beam collimation such that, for example, if the laser beam is collimated when entering the beam width adjustment optics group, it is also collimated when leaving the laser beam width adjustment optics group. However, for example, if the laser beam is collimated when entering the beam width adjustment optics group and slightly convergent or slightly divergent when leaving the laser beam width adjustment optics group, the beam width adjustment optics group can also be considered to maintain constant laser beam collimation. Similarly, for example, if the laser beam diverges slightly when entering the beam width adjustment optics and converges slightly when leaving the laser beam width adjustment optics, the beam width adjustment optics can also be considered to keep the laser beam collimated constant.

[0016] "Slight" divergence or convergence in this article can refer to the divergence or convergence angle of the laser beam measured between the beam width adjustment optics group and the focusing optics group, respectively, which may be no greater than 10°, no greater than 6°, and even no greater than 3°.

[0017] In other words, the beam width adjustment optics can be configured to avoid (i.e., not cause) significant changes in the collimation, divergence, and / or convergence of the laser beam. Specifically, the beam width adjustment optics can be configured to cause a change in the absolute value of the beam propagation angle of the laser beam of no more than 10°, no more than 6°, more likely no more than 3°, and possibly 0°. "Beam propagation angle" herein can refer to the convergence angle for converging the beam and the divergence angle for diverging the beam. A collimated beam can be considered to have a beam propagation angle of 0°.

[0018] Therefore, for example, if laser beam B has a beam propagation angle of 0° when it reaches the beam width adjustment optics, this means that laser beam B is collimated, and laser beam B can be converged when it leaves the beam width adjustment optics, with a convergence angle no greater than 10°. As another example, if laser beam B has a divergence angle of 5° when it reaches the beam width adjustment optics, this means that laser beam B is slightly divergent, and laser beam B can have a convergence angle, for example, between 0° and 15° (i.e., the absolute value deviates from 5° by no more than 10°) when it leaves the beam width adjustment optics.

[0019] In this paper, "divergence angle" refers to the angle between the diverging ray of a laser beam and the optical axis of the laser beam as the laser rays travel along their beam path toward the focal point. Geometrically, the divergence angle can be measured as twice the angle between the optical axis and the maximum scattering ray of the laser beam. Therefore, a larger divergence angle is associated with a smaller spot size at the focal point, while a smaller divergence angle is associated with a larger spot size at the focal point. Similarly, "convergence angle" refers to the angle between the converging ray of a laser beam and the optical axis of the laser beam as the laser rays travel along their beam path toward the focal point. Geometrically, the convergence angle can be measured as twice the angle between the optical axis and the maximum converging ray. Therefore, a larger convergence angle is associated with a smaller beam width incident on the focusing optics, and thus with a larger spot size at the focal point, while a smaller convergence angle is associated with a larger beam width incident on the focusing optics, and thus with a smaller spot size at the focal point.

[0020] Alternatively or additionally, the beam width adjustment optics can be configured to adjust the beam width of the laser beam such that the ratio of the distance from the beam width adjustment optics to the focusing optics described below (e.g., the distance between the downstream lens of the beam width adjustment optics and the upstream lens of the focusing optics) to the Rayleigh length of the laser beam measured downstream of the beam width adjustment optics (specifically, downstream of the beam width adjustment optics and upstream of the focusing optics) is not greater than 1000, and may be not greater than 60, 30, or 10. "Distance" herein may refer to geometric distance in the Euclidean sense.

[0021] The Rayleigh length of a laser beam is an optical parameter defined as the distance from the so-called beam waist (the point along the optical path where the beam reaches its minimum beam width) to the point where the beam cross-sectional area has doubled. The beam can be considered to begin diverging more significantly beyond this distance. For example, for a Gaussian beam, the Rayleigh length zR is defined as zR = (πω) / (πω) 2 ω / λ, where ω represents the beam radius at the beam waist (i.e., half the beam width), and λ is the wavelength of the laser beam. Those skilled in the art will understand how to adjust this mathematical expression as needed for laser beams comprising more than one single wavelength (e.g., a wavelength range).

[0022] For example, a laser beam input to a laser processing apparatus has a wavelength of 1050 nm and a beam waist of 12 mm, with a Rayleigh length of 43085 m. This indicates that the laser beam can be considered to begin diverging significantly after an optical distance of 43085 m. According to this example, and considering a distance of, for example, 25 mm from the beam width adjustment optics to the focusing optics, the beam width adjustment optics, according to the invention, can be configured to maintain a Rayleigh length measured downstream of the beam width adjustment optics greater than 25 mm, preferably greater than 417 mm, and more preferably greater than 83 mm.

[0023] According to another example, if the same laser beam having a wavelength of 1050 nm and a beam waist of 12 mm is input into a laser processing apparatus, and considering that the distance from the beam width adjustment optics to the focusing optics is, for example, 75 mm, then according to the invention, the beam width adjustment optics can be configured to maintain a Rayleigh length measured downstream of the beam width adjustment optics greater than 75 mm, preferably greater than 125 mm, and more preferably greater than 25 mm.

[0024] It is important to note that the "Rayleigh length" is a parameter that defines both converging and diverging laser beams. For a laser beam converged to a focal point (beam waist), the Rayleigh length is the distance from that beam waist to the point where the cross-sectional area of ​​the beam doubles due to divergence. Beyond this Rayleigh length, the beam continues to diverge, but at a more significant rate. In a diverging beam (e.g., a beam that has already passed through the focal point), the Rayleigh length similarly represents the distance from the beam waist (where the beam is most tightly focused) to the point where the cross-sectional area doubles due to continuous expansion.

[0025] Therefore, the beam width adjustment optics can be optionally configured for at least one of the following: - The absolute value of the change in the beam propagation angle of the laser beam shall not exceed 10°, may not exceed 6°, and may not exceed 3°; and - Ensure that the ratio of the distance along the optical path of the laser beam from the beam width adjustment optics to the focusing optics to the Rayleigh length of the laser beam measured downstream of the beam width adjustment optics (specifically downstream of the beam width adjustment optics and upstream of the focusing optics) is not greater than 1000, and may not be greater than 60, and may not be greater than 30.

[0026] The optical distance from the beam width adjustment optical system to the focusing optical group can specifically be the distance from the downstream (i.e., closest to the focusing optical group) optical component of the beam width adjustment optical group (e.g., a fixed lens of the beam width adjustment optical group) to the upstream (i.e., closest to the beam width adjustment optical group) optical component of the focusing optical group (e.g., a movable lens of the focusing optical group).

[0027] By adjusting the beam width of the laser beam using a beam width adjusting optics group, the beam width of the laser beam downstream of the beam width adjusting optics group can be controlled. For this purpose, the beam width adjusting optics group includes at least two lenses, each including at least one movable lens for adjusting the convergence or divergence of the laser beam.

[0028] As used herein, "upstream" and "downstream" can refer to the direction of the laser beam defined from the laser input section toward the laser output section. If element A is referred to as upstream of element B, this indicates that A is closer to the corresponding laser input section than B along the path of the laser beam. Similarly, if element C is referred to as downstream of element V, this indicates that C is closer to the laser output section than B along the path of the laser beam.

[0029] The beam width adjustment optics may further include at least one fixed (immovable) lens, with at least two lenses comprising a movable lens and a fixed lens, the movable lens being positioned upstream of the fixed lens along the beam path of the laser beam. The convergence or divergence of the laser beam input to the laser processing apparatus, and possibly any other laser beams, can be adjusted by correspondingly moving (specifically, shifting) at least one movable lens of the beam width adjustment optics along the propagation direction of the laser beam (i.e., along the optical axis). At least one movable lens of the beam width adjustment optics may be a converging lens and may have a larger dimension (e.g., a larger diameter) than at least one of the other two lenses of the beam width adjustment optics (e.g., more than at least one fixed (immovable) lens).

[0030] "Beam width" as used herein may refer to the width or diameter of the laser beam in a plane perpendicular to the direction of propagation of the laser beam (i.e., the cross-section of the laser beam). Since laser beams typically do not have sharp edges, beam width as used herein may refer to the beam width or beam diameter defined according to any definition known to those skilled in the art (including D4σ, 10 / 90 or 20 / 80 knife edge, 1 / e2, FWHM, and D86). For cases where the laser beam may have a non-circular cross-section, "beam width" may be defined relative to the major or minor axis of the laser beam's cross-section.

[0031] The "beam width," determined by the beam width adjustment optics, affects the spot size or focal diameter (i.e., the beam width of the laser beam at its focal point). The spot size can also be understood as the minimum beam width or minimum beam waist of the laser beam corresponding to the position of the laser beam's focal point along the optical path of the laser beam.

[0032] Therefore, the beam width adjustment optics can adjust the beam width of the laser beam and thus controllably influence the beam width of the laser beam at any position downstream of the beam width adjustment optics, specifically between the beam width adjustment optics and the focusing optics, and / or at the position where the focal point of the laser beam is located along the optical path of the laser beam.

[0033] As used herein, “beam shape” can refer to the cross-sectional shape of a laser beam, or the shape of its intensity distribution. The beam shape can be, for example, circular, elliptical, cross-shaped, or polygonal, or can correspond to a superposition of multiple circles or ellipses. “Beam intensity distribution” can refer to the spatial distribution of laser intensity across the cross-section of the laser beam. For example, the beam intensity distribution of a laser beam with a circular cross-section can follow a Gaussian distribution, with a peak at the center and a Gaussian decay towards the periphery of the beam cross-section.

[0034] The beam width adjustment optics can be configured to adjust the beam width of a collimated laser beam, or at most slightly divergent or slightly convergent without substantially affecting collimation. This means that although the beam width of the laser beam after passing through the beam width adjustment optics can vary relative to the beam width before reaching the beam width adjustment optics, the laser beam can remain collimated or at most slightly divergent or slightly convergent after passing through the beam width adjustment optics. Therefore, the laser beam can be collimated or at most slightly divergent or slightly convergent immediately upstream and immediately downstream of the beam width adjustment optics, while having different beam widths and different divergence angles.

[0035] The laser processing apparatus also includes a focusing optics group with an adjustable focal length. The focusing optics group is arranged along the beam path of the laser beam between the beam width adjustment optics group and the laser output section. The focusing optics group includes at least two lenses, and at least one of the at least two lenses is a movable lens.

[0036] The focusing optics group can adjust the focal length (i.e., its "effective focal length") of the overall optical system of the laser processing apparatus by adjusting its own focal length, while taking into account the beam width adjustment optics group, the focusing optics group, and any other optical groups or components of the laser processing apparatus that may help determine its total focal length. By adjusting the focal length of the optical system of the laser processing apparatus, the focusing optics group can determine the focal position of the laser beam output through the laser output unit and the focal position of any other laser beams from the beam width adjustment optics group. Therefore, the focusing optics group can set the focal position of the laser beam, for example, in the working area and / or on the workpiece to be laser-processed.

[0037] The focusing optics group may further include at least one fixed (immovable) lens, with at least two lenses comprising a movable lens and a fixed lens. For example, the focusing optics group may include a movable lens and a fixed lens, wherein the movable lens is positioned upstream of the fixed lens along the beam path of the laser beam. Therefore, the focal position of the laser beam input to the laser processing apparatus, and possibly the focal position of any other laser beam, can be adjusted by correspondingly moving (specifically, shifting) at least one movable lens of the focusing optics group. The at least one movable lens of the focusing optics group may be a diverging lens and may have a smaller size than at least one of the other two lenses in the focusing optics group (e.g., smaller than at least one fixed (immovable) lens).

[0038] The at least two lenses of the focusing optics group and the at least two lenses of the beam width adjustment optics group can be different lenses. Therefore, the laser processing apparatus of the present invention can include at least four lenses, wherein at least two of the at least four lenses can correspond to the beam width adjustment optics group, and at least two other lenses of the at least four lenses can correspond to the focusing optics group.

[0039] Each of the beamwidth adjustment optics group and the focusing optics group may include a corresponding motor system for driving movement of at least one movable lens. The motor system of the beamwidth adjustment optics group for driving movement of its at least one movable lens may be different from the motor system of the focusing optics group for driving movement of its at least one movable lens. The motor systems of the beamwidth adjustment optics group and the focusing optics group may operate independently of each other and / or may be controlled by independent control units or control modules. For example, the motor system of the beamwidth adjustment optics group may be controlled by a first control module, and the motor system of the focusing optics group may be controlled by a second control module.

[0040] The optical system of the laser processing apparatus of the present invention is configured to simultaneously or independently adjust the focal position of the laser beam and the spot size corresponding to the beam width of the laser beam at the focal position. By means of the combination and coordination of the beam width adjusting optical group and the focusing optical group, the laser processing apparatus can thus set the focal position and / or spot size of the laser.

[0041] Adjusting both the focal position and the laser beam simultaneously could mean manipulating the beamwidth adjustment optics and the focusing optics, allowing both the focal position and the laser beam to change concurrently. For example, the focal position of the laser beam could be shifted while increasing the spot size.

[0042] If the focal position and the laser beam are adjusted independently, this could mean that the beamwidth adjustment optics and the focusing optics can be operated so that one of the focal position or the laser beam changes while the other remains constant. For example, the focal position of the laser beam can remain constant while the spot size increases or decreases, or the spot size can remain constant while the focal position shifts.

[0043] The optical system can be operated to maintain a constant focal position of the laser beam or, on a target plane (such as the working area of ​​a laser processing device or the surface of a workpiece being laser-processed), simultaneously change the spot size of the laser beam or simultaneously maintain a constant spot size. Furthermore, for example, when changing the target plane or when guiding the laser beam to different positions on the working area, the optical system can be operated to maintain a constant spot size of the laser beam while changing the focal position.

[0044] A beam width adjustment optics group can be considered a telescope optical system configured to provide adjustable zoom or magnification, which, when operated in conjunction with a focusing optics group, allows for adjustment of the effective focal length of the entire optical system, where adjusting the beam width is equivalent to adjusting the zoom provided by the telescope system.

[0045] A focusing optics group can be considered a so-called objective lens optics system configured to control the focal length of the optical system of a laser processing apparatus, allowing the focal position of the laser beam to be moved or kept constant. The focusing optics group can alter the convergence or divergence of the laser beam to shift its focal position. For this purpose, the focusing optics group can adjust the position of at least one movable lens to adjust the effective focal length of the focusing optics group accordingly. Thus, the focal position of the laser beam can be dynamically adjusted to achieve precise focusing on the workpiece and / or working area to be laser-processed.

[0046] Therefore, by combining the beam width adjustment optics with the focusing optics, the laser processing apparatus of the present invention can achieve highly dynamic magnification or reduction (i.e., beam width adjustment), while allowing adjustment of the focal length of the optical system of the laser processing apparatus. Specifically, it is used as needed to keep the focal position of the laser beam constant during or after changes in beam width (spot size), or to keep the beam width (spot size) constant during or after changes in focal position.

[0047] Typically, any change in the beam width or spot size of a laser beam can trigger a shift in the effective focal length of the laser processing apparatus, and thus a shift in the focal position of the laser beam. Therefore, generally, if the beam width of the laser beam is adjusted, or if laser beams with different beam widths are input through the laser input section, the focal position of the laser beam will change in an uncontrolled and potentially undesirable manner. In the laser processing apparatus of the present invention, the combination of the beam width adjustment optics and the focusing optics allows for readjustment of the focal length of the optical system of the laser processing apparatus when necessary, for example, maintaining the focal position at the position prior to changes in beam width or spot size. Therefore, for example, using the laser processing apparatus of the present invention, the spot size can be increased or decreased while maintaining a constant focal position of the laser beam.

[0048] Similarly, any change in the focal position of a laser beam can typically trigger a corresponding change in its spot size. Therefore, if the focal position of the laser beam is adjusted, for example, during planar region compensation to guide the laser beam to different positions on a planar working area in order to maintain the focus on the planar working area, the spot size may change in an uncontrolled and potentially undesirable manner. In the laser processing apparatus of the present invention, the combination of the beam width adjustment optics and the focusing optics allows the spot size of the laser beam to be readjusted as needed to maintain it constant, i.e., the beam width of the laser beam at the focal position is the same as before the focal position change.

[0049] Furthermore, the configuration according to the invention allows the beam shape and intensity distribution of the laser beam to be maintained downstream of the laser processing apparatus after the beam width and focal position have been adjusted.

[0050] Therefore, the laser processing apparatus of the present invention provides greater operational flexibility than previously known solutions (such as those known from each of EP3838472A1 and US 2005 / 0150876A1), achieving a variable spot size with a constant focal position. Compared to those solutions, the laser processing apparatus of the present invention can operate flexibly with a wider range of beam widths, particularly when a laser beam that satisfies at least one of the two conditions defined above (e.g., when the laser beam is collimated, slightly convergent, or slightly divergent) is input, the beam width of the laser beam can be adjusted by the beam width of at least one laser beam, and it can be operated with laser beams input through the laser input section with a wider range of beam shapes and beam intensity distributions.

[0051] According to a preferred embodiment, the laser processing apparatus may further include a first control module configured to control the movement of at least one movable lens of the beam width adjusting optics and at least one movable lens of the focusing optics, so as to change the spot size of the laser beam while keeping the focal position of the laser beam constant.

[0052] Alternatively or additionally, the laser processing apparatus may include a second control module configured to control the movement of at least one movable lens of the beam width adjusting optics and at least one movable lens of the focusing optics, so as to change the focal position of the laser beam while keeping the spot size of the laser beam constant.

[0053] The first control module and / or the second control module can be specifically configured to perform adjustment of the spot size (i.e., the beam width of the laser beam at its focal position). This specifically means that, when adjusting the beam width, the target parameter (possibly using a corresponding optical monitoring system) tracked by the first control module and / or the second control module can be the spot size or focused diameter of the laser beam.

[0054] The combined functionality of the first and second control modules can provide enhanced flexibility and precision in laser processing using the laser processing apparatus of the present invention. The ability to flexibly adjust the spot size and effective focal length of the laser processing apparatus can be beneficial for a variety of laser processing applications. For example, in applications requiring a constant spot size (beam width at the focal point), such as for welding purposes, the laser processing apparatus can maintain a constant spot size as needed while adjusting the focal position of the laser beam (by adjusting the focal length of the laser processing module), for example, when scanning a planar working area, by adjusting as a function of the deflection angle to compensate for variations in the beam path distance to the working area or workpiece (which increases with the deflection angle). Similarly, for other applications, it may be desirable to maintain a constant focal position while adjusting the beam width.

[0055] It is worth noting that the solution disclosed in EP 3838472A1 is based on the use of a focusing optics group with at least two movable lenses, rather than on a combination of a beam width adjustment optics group with at least one movable lens and a focusing optics group with at least one movable lens, which can be independently controlled and operated according to the present invention. Therefore, the solution disclosed in EP 3838472A1, for a limited range of laser beam widths input to the corresponding laser input section, provides the possibility of adjusting the beam spot size or beam width of the laser beam while keeping the focal position of the laser beam constant. In contrast, the laser processing apparatus of the present invention, for a wider range of laser beam widths input to the corresponding laser input section, provides the possibility of adjusting the beam spot size or beam width of the laser beam while keeping the focal position of the laser beam constant.

[0056] According to a preferred embodiment, the laser processing apparatus may further include a third control module for controlling the movement of at least one movable lens of the beam width adjusting optics group to adjust the beam width of the laser beam. Specifically, this adjustment is a beam width of the laser beam measured along the optical path of the laser beam at a position between the beam width adjusting optics group and the focusing optics group. This beam width may be measured at the upstream optical element (e.g., a lens) of the focusing optics group (i.e., when the laser beam is incident on the first optical surface of the focusing optics group), corresponding to a target value associated with the focusing optics group. For this purpose, the second control module may receive, for example, from a user interface or a pre-programmed instruction set, or automatically detect, the settings of the focusing optics group (e.g., the target focal position of the laser beam and / or the position of one of the at least one movable lens of the focusing optics group), and determine based on this the target value of the beam width imparted by the settings of the focusing optics group. The second control module can then correspondingly control at least one movable lens of the beam width adjusting optics group to adjust the beam width of the laser beam corresponding to this target value (specifically, it may correspond to the target value of the beam width of the laser beam when it enters the focusing optics group). This specifically means that when adjusting the beam width, the target parameter tracked by the second control module (which can use a corresponding optical monitoring system) can be the beam width of the laser beam at the position between the beam width adjustment optical group and the focusing optical group along the optical path of the laser beam.

[0057] Each of the first, second, and third control modules, which can be separate modules or functional components of the same module, can be implemented in hardware or software. For example, in some embodiments, the first, second, and third control modules can be independent hardware, while in other embodiments, the first, second, and third control modules can be software modules implemented by a single control processing unit.

[0058] In a preferred embodiment, the laser processing apparatus may include a scanning unit for scanning a laser beam across a working area in a two-dimensional direction. The scanning unit may include an XY pair of movable mirrors, each including a corresponding galvanometer, for scanning the laser beam. The scanning unit may preferably be arranged downstream of the beam width adjustment optics and focusing optics along the beam path of the laser beam. In other words, the laser processing apparatus of the present invention may be a pre-focusing device in which the laser beam is focused by the focusing optics before being deflected by the scanning unit.

[0059] In a preferred embodiment, the laser processing apparatus may include at least one collimating optical system for collimating a laser beam upstream of the beam width adjustment optical group (which may be upstream of the laser input section). Therefore, at least one collimating optical system, which may be partially or entirely arranged upstream of the beam width adjustment optical group and also upstream of the laser input section, can ensure that the laser beam reaching both the beam width adjustment optical group and the focusing optical group is a collimated laser beam.

[0060] According to a preferred embodiment, the laser processing apparatus may further include at least one beam adjustment element (preferably at least one diffractive optical element) for adjusting the beam shape and / or beam intensity distribution of the laser beam upstream of the beam width adjustment optical group (which may be upstream of the laser input section). At least one collimating optical system, which may be partially or entirely arranged upstream of the beam width adjustment optical group and also upstream of the corresponding laser input section, can ensure that the laser beam reaching the beam width adjustment optical group and the focusing optical group has the desired beam shape and / or the desired beam intensity distribution.

[0061] In a preferred embodiment, the laser processing apparatus may further include at least one dichroic element disposed upstream of the beam width adjusting optical group, wherein the at least one dichroic element may be at least partially transparent to a first laser beam input to the laser processing apparatus via a first laser input section and output to the laser processing apparatus via a laser output section, and may be at least partially reflective to a second laser beam input to the laser processing apparatus via a second laser input section and output to the laser processing apparatus via a laser output section. Those skilled in the art will understand that the number of laser input sections and the number of laser beams input to the laser processing apparatus of the present invention may be greater than two.

[0062] In this embodiment, at least one collimating optical system and at least one beam adjustment element previously described can each be arranged in the beam path of a corresponding laser beam input to the laser processing apparatus, with the possibility that at least one collimating optical system and at least one beam adjustment element can be configured differently or the same for different laser beams.

[0063] The first and second laser beams can satisfy at least one or a combination of the following conditions, which specifically refer to the characteristics of the respective laser beams when input into a laser processing apparatus or when reaching the beam width adjustment optics: - The first laser beam and the second laser beam have different beam widths; - The first laser beam and the second laser beam have different wavelength ranges; - The first laser beam and the second laser beam have different beam shapes; - The first laser beam and the second laser beam have different intensity distributions; - The first laser beam and / or the second laser beam is or includes a single-mode laser beam preferably obtained from the central fiber core of a coaxial fiber; - The first laser beam and / or the second laser beam is or includes a ring-shaped multimode laser beam preferably obtained from the outer fiber loop of the coaxial fiber.

[0064] One or more laser beams are input into the laser processing apparatus via corresponding laser input sections, thus allowing for the flexible overlapping of laser beams with different characteristics. For example, the first and second laser beams can have different beam widths to allow for an effective increase in the zoom range or magnification range achievable by the beam width adjustment optics. As another example, the first and second laser beams can have different wavelength ranges, such that the first laser beam can be used, for example, for laser processing, while the second laser beam can be used for coaxial illumination or optical monitoring purposes, or for different types of laser processing. Advantageously, the laser width and focal position of all laser beams input into the system can be simultaneously adjusted by the beam width adjustment optics and the focusing optics.

[0065] The optical characteristics (particularly focal length and relative position) of the lenses included in the beam width adjustment optics can be adapted to the function of the beam width adjustment optics. Preferably, the lenses of the beam width adjustment optics can be selected such that they are matched with the beam width of the laser beam input through the laser input section. The ratio of the beam width of the laser beam input through the laser input section to the maximum beam width compatible with the focusing optics can determine the required focal lengths of at least two lenses of the beam width adjustment optics and their corresponding distances to each other in a manner available to those skilled in the art.

[0066] The optical characteristics (specifically, focal length and relative position) of the lenses included in the focusing optics group can be adapted to the function of the focusing optics group. Preferably, given the maximum beam width of the optical system of a laser processing apparatus (which can be determined by the diameter of the smallest lens or mirror in the optical system), the desired focal length and position of at least two lenses in the focusing optics group can be derived from the desired optical distance to the focal plane (e.g., the desired optical distance to the working area or to the workpiece) in a manner available to those skilled in the art.

[0067] Another aspect of the invention relates to a method of operating a laser processing apparatus for laser-processing workpieces (particularly a laser processing apparatus according to any of the embodiments of the first aspect of the invention described above). The method includes inputting at least one laser beam into the laser processing apparatus through at least one laser input section, and outputting at least one laser beam through a laser output section of the laser processing apparatus.

[0068] In addition, the method includes: - Operate the beam width adjustment optics of the laser processing apparatus to adjust the beam width (specifically, the spot size (i.e., the beam width at the focal point of the laser beam)) of at least one laser beam; or - Operate the focusing optical system of the laser processing apparatus to adjust the focal position of at least one laser beam; or - Operate the beam width adjustment optics of the laser processing apparatus to adjust the beam width of at least one laser beam, and operate the beam width adjustment optics and focusing optics of the laser processing apparatus to adjust the focal position of at least one laser beam and the spot size corresponding to the beam width of the laser beam at the focal position.

[0069] According to this method, the beam width of at least one laser beam can optionally be adjusted by a beam width adjusting optics group while satisfying at least one of the following: The absolute value of the laser beam propagation angle varies by no more than 10°, and can be no more than 6° or no more than 3°; and The ratio of the distance along the optical path of the laser beam from the beam width adjustment optics to the focusing optics to the Rayleigh length of the laser beam measured downstream of the beam width adjustment optics (specifically downstream of the beam width adjustment optics and upstream of the focusing optics) is no greater than 1000, and may be no greater than 60, no greater than 30, or even no greater than 10.

[0070] This method may include beam width adjustment optics and focusing optics that can be operated simultaneously and / or independently to adjust the focal position and spot size of the laser beam. The beam width adjustment optics and focusing optics of the laser processing apparatus can operate sequentially or simultaneously, one after another, for the same laser beam or for different laser beams, within a reaction time of less than 1 second, preferably less than 0.1 seconds.

[0071] The method may include operating a beam width adjustment optics group of a laser processing apparatus to adjust the beam width while keeping the collimation of the laser beam (B) substantially unchanged.

[0072] The beam width adjusting optics and focusing optics can be operated to change the spot size (i.e., beam width at the focal position) of at least one laser beam while keeping the focal position of at least one laser beam constant, thereby compensating for uncontrolled changes in the focal position of at least one laser beam triggered by changes in the beam width (specifically, spot size) of at least one laser beam. Therefore, adjusting the focal position of at least one laser beam can include keeping the focal position constant after or during a corresponding beam width change.

[0073] The beam width adjusting optics and focusing optics can be operated to change the focal position of at least one laser beam while keeping the spot size (i.e., the beam width at the focal position of the laser beam) constant, thereby compensating for uncontrolled changes in the beam width (specifically, the spot size) triggered by changes in the focal position of at least one laser beam. Therefore, adjusting the spot size of at least one laser beam includes keeping the beam width constant after or during a corresponding focal position change.

[0074] In either case, the focal position of at least one laser beam can be adjusted by correspondingly adjusting the focal length of the optical system of the laser processing apparatus using the beam width adjustment optics and the focusing optics. It is worth noting that both the beam width adjustment optics and the focusing optics can affect the spot size and focal position of at least one laser beam.

[0075] In a preferred embodiment, the beam width adjustment optics and focusing optics of the laser processing apparatus can be operated to increase or decrease the beam width of at least one laser beam by a factor of 2 or more, or by a factor of 3 or more, or even by a factor of 4 or 5 or more. Therefore, the first beam width of the laser beam before adjustment by the optical system of the laser processing apparatus and the second beam width of the laser beam after adjustment by the optical system can differ by a factor of 2, 3, 4, 5 or more. This means that the second beam width can be at least twice the first beam width or at most half the first beam width, or at least three times the first beam width or at most one-third of the first beam width, or at least four or five times the first beam width or at most one-quarter or one-fifth of the first beam width, etc. This can be specifically applied to the spot size: the first spot size of the laser beam before adjustment by the laser processing apparatus and / or by the method according to the invention can differ from the second spot size of the laser beam after adjustment by the laser processing apparatus and / or by the method according to the invention by a factor of 2, 3, 4, 5, or more. This means that the second spot size can be at least twice the first spot size or at most half the first spot size, or at least three times the first spot size or at most one-third the first spot size, or at least four or five times the first spot size or at most one-quarter or one-fifth the first spot size, etc. It is possible that this change in spot size can be performed while keeping the focal position of at least one laser beam constant. It is noteworthy that, as explained above, the spot size changes inversely with the width of the second beam: if the width of the second beam increases relative to the width of the first beam, the spot size decreases, and vice versa.

[0076] According to a preferred embodiment, a beam width adjustment optical group and a focusing optical group that can be controlled by a corresponding hardware-based or software-based control processing unit can be operated to change the beam width (preferably specifically the spot size) of at least one laser beam while keeping the focal position of at least one laser beam constant, or to change the focal position of at least one laser beam while keeping the beam width (preferably specifically the spot size) of the laser beam constant.

[0077] Optionally, when at least one laser beam enters the laser processing apparatus through a corresponding laser input section of at least one laser input section, the at least one laser beam may be a collimated laser beam. Additionally or optionally, the beam shape and / or beam intensity distribution of the at least one laser beam may be adjusted before it passes through the beam width adjusting optics group and the focusing optics group.

[0078] Preferably, at least one laser input section may be without any fiber optic coupling device and / or thus may be adapted to input a corresponding collimated laser beam having any beam shape and / or any beam intensity distribution.

[0079] Specifically, when the laser processing apparatus includes the above-described configuration comprising at least one dual-color element, the method may further include: inputting a first laser beam into the laser processing apparatus via a first laser input section; inputting a second laser beam into the laser processing apparatus via a second laser input section; outputting the first laser beam and the second laser beam via a laser output section; operating a beam width adjustment optics group of the laser processing apparatus to adjust the beam width of the first laser beam and / or the second laser beam; and / or operating the beam width adjustment optics group and the focusing optics group of the laser processing apparatus to respectively adjust the focal position of the first laser beam and / or the second laser beam and the spot size of the first laser beam and / or the second laser beam corresponding to the beam width of the first laser beam and / or the second laser beam at the focal position.

[0080] In this case, the beam width of the first laser beam and / or the second laser beam can be adjusted by the beam width adjustment optics while satisfying at least one of the following: - The absolute value of the change in the beam propagation angle of the corresponding laser beam shall not exceed 10°, may not exceed 6°, and may even not exceed 3°; and - The ratio of the distance from the corresponding beam width adjustment optics system to the focusing optics system along the optical path of the corresponding laser beam to the Rayleigh length of each laser beam measured downstream of the beam width adjustment optics group (specifically downstream of the beam width adjustment optics group and upstream of the focusing optics system) is not greater than 1000, and may not be greater than 60, may not be greater than 30, or may not be greater than 10.

[0081] Therefore, these optional or cumulative conditions can be applied to one or both of the first and second laser beams.

[0082] Preferably, the first laser beam and the second laser beam can satisfy at least one or a combination of the following conditions, which can specifically refer to the characteristics when the respective laser beam is input into the laser processing device or reaches the beam width adjustment optics (not applicable to conditions involving spot size): - The first laser beam and the second laser beam have different beam widths and / or different spot sizes; - The first laser beam and the second laser beam have different wavelength ranges; - The first laser beam and the second laser beam have different beam shapes; - The first laser beam and the second laser beam have different intensity distributions; - The first laser beam and / or the second laser beam is or includes a single-mode laser beam preferably obtained from the central core of a coaxial fiber; - The first laser beam and / or the second laser beam is or includes a ring-shaped multimode laser beam preferably obtained from the outer fiber loop of the coaxial fiber.

[0083] The method may include operating either the beam width adjustment optics group or the focusing optics group of the laser processing apparatus for any of the following: - Adjust the spot size of the first laser beam and / or the spot size of the second laser beam (B2); - While keeping the focal position of the first laser beam constant, change the spot size of the first laser beam; - While keeping the focal position of the second laser beam constant, change the spot size of the second laser beam; - While keeping the spot size of the first laser beam constant, change the focal position of the first laser beam; and - While keeping the spot size of the second laser beam constant, change the focal position of the second laser beam.

[0084] In the method of the present invention, laser processing of workpieces may include performing laser powder bed fusion or laser welding processes, specifically for welding bipolar plates of battery cells and / or combustible batteries. Attached Figure Description

[0085] Figure 1 A schematic diagram of a laser processing apparatus according to some embodiments of the present invention is shown.

[0086] Figure 2 This shows the situation when the focusing optics are not operated after operating the beam width adjustment optics. Figure 1 Laser processing.

[0087] Figure 3 It shows the relationship with Figure 1 and Figure 2 Compared to the previous configuration, this is a schematic diagram showing the separation of the optical components of the beam width adjustment optics and the focusing optics when only the spot size of the laser beam is changed without adjusting the focal position of the laser beam.

[0088] Figure 4 This shows the operation after the beam width adjustment optics group and the focusing optics group. Figure 1 Laser processing.

[0089] Figure 5 It shows the relationship with Figure 1 and Figure 3 Compared to the configuration, this is a schematic diagram showing the separation of the optical components of the beam width adjustment optics and the focusing optics according to the present invention when the spot size of the laser beam is changed and the focal position of the laser beam is adjusted.

[0090] Figure 6A schematic side view showing a comparison of the spot size of a laser beam deflected by a laser processing apparatus according to the present invention is shown. Figure 6 A corresponds to Figure 1 The corresponding part shown. Figure 6 B corresponds to Figure 4 The corresponding part shown.

[0091] Figure 7 A schematic top view showing a comparison of the spot size of a laser beam deflected by a laser processing apparatus according to the present invention is shown. Figure 7 A corresponds to Figure 1 and Figure 6 The corresponding part shown in A. Figure 7 B corresponds to Figure 4 and Figure 6 The corresponding part shown in B.

[0092] Figure 8 A schematic diagram of a laser processing apparatus according to some embodiments of the present invention is shown.

[0093] Figure 9 This is a schematic flowchart of a method according to an embodiment of the present invention.

[0094] Figure 10 This is a schematic flowchart of a method according to an embodiment of the present invention.

[0095] Figure 11 This is a schematic flowchart of a method according to an embodiment of the present invention. Detailed Implementation

[0096] To facilitate understanding of the principles of the invention, reference will now be made to specific preferred embodiments shown in the accompanying drawings, and these embodiments will be described using specific language. However, it will be understood that this is not intended to limit the scope of the invention in any way, and such alternatives and further modifications to the illustrated apparatus that may be readily conceived by those skilled in the art, both now and in the future, as well as further applications of the principles of the invention in the illustrated scenarios, are all within the scope defined by the claims.

[0097] exist Figures 1 to 6 The same reference numerals are used to denote the same elements.

[0098] Figure 1 A schematic diagram of a laser processing apparatus 10 according to some embodiments of the present invention is shown. The laser processing apparatus can be used to laser process a workpiece P arranged on a work area 13, which may be planar, for example, by performing a laser powder bed fusion process or a laser welding process, and can be used to weld bipolar plates of a battery cell or fuel cell.

[0099] The device 10 includes an optical system comprising a beam width adjustment optical group 20 and a focusing optical group 30, and a scanning unit 40, wherein the beam width adjustment optical group 20, the focusing optical group 30, and the scanning unit 40 are surrounded by a housing 11. A laser input section 12, which can be configured as a first glass window, and a laser output section 14, which can be configured as a second glass window, are formed by the dustproof and waterproof housing 11. A laser beam B is input into the device 10 through the laser input section 12 and output through the laser output section 14. The laser beam B is guided by the scanning unit 40 to a working area 13, in which a workpiece P to be laser-processed is arranged. The laser input section may have an aperture AP of 5 mm to 50 mm.

[0100] When laser beam B is input into device 10 through laser input section 12, laser beam B has a given collimation. Figure 1 In the example, laser beam B is collimated when it is input into device 10 via laser input section 12. In other related embodiments, laser beam B may be slightly converged or slightly diverged when it is input into device 10 via laser input section 12. Furthermore, when laser beam B is input into device 10 via laser input section 12, laser beam B has a given Rayleigh length, for example, a collimated laser beam B with a wavelength of 1070 nm and a beam waist of 20 mm (minimum beam width) has a Rayleigh length of 1174.43 m.

[0101] The beam width adjustment optics group 20 and the focusing optics group 30 are configured to selectively adjust the spot size of the laser beam B (i.e., the beam width of the laser beam corresponding to the focal position F (also referred to as the "focal diameter")) and the focal position F of the laser beam B. The beam width adjustment optics group 20 and the focusing optics group 30 can adjust or maintain the focal position F of the laser beam B at a target position on the workpiece P or the working area 13.

[0102] In the illustrated embodiment, the beam width adjustment optics group 20 reduces the beam width from a first beam width W1 when the laser beam B enters through the laser input section 12 to a second beam width W2 at a position along the beam path of the laser beam between group 20 and group 30, where W2 < W1. However, in other embodiments, W2 may be greater than W1. The beam width adjustment optics group 20 can operate to obtain values ​​in a continuous range of W2 ≤ W1 / 2, W2 ≤ W1 / 3, W2 ≤ W1 / 4 or smaller, or for other configurations to obtain values ​​of W2 ≥ 2W1, W2 ≥ 3W1, W2 ≥ 4W1 or larger.

[0103] In the illustrated embodiment, the beam width adjustment optics 20 includes a movable lens 22 and a fixed lens 24. In related embodiments, the beam width adjustment optics 20 may include a greater number of movable lenses and / or fixed lenses. The position of the movable lens 22 can be adjusted to change the second beam width W2 of the laser beam B, and thus change the spot size of the laser beam. Notably, the spot size changes inversely with the second beam width W2: if the second beam width W2 increases relative to the initial beam width W1, the spot size decreases, and vice versa. The operation of the beam width adjustment optics 20 (particularly the movement of the movable lens 22) is controlled by a control processing unit 50. For this purpose, the control processing unit 50 is operatively coupled to the motor system (not shown) of the beam width adjustment optics 20 and the motor system (not shown) of the focusing optics 30.

[0104] Downstream of the beam width adjustment optics group 20 is the focusing optics group 30. In the illustrated embodiment, the focusing optics group 30 includes a movable lens 32 and a fixed lens 34. In related embodiments, the focusing optics group 30 may include a greater number of movable lenses and / or fixed lenses. The movable lens 32 can be displaced to change the effective focal length of the laser processing apparatus 10, thereby facilitating the adjustment of the focal position F of the laser beam B, which is also affected by the setting of the beam width adjustment optics group 20. The operation of the focusing optics group 30 (particularly the movement of the movable lens 32) is controlled by the control processing unit 50.

[0105] W2 can correspond to the beam width of the laser beam B as measured when the laser beam B is incident on the movable lens 32 of the focusing optics group 30.

[0106] In this exemplary embodiment, the distance between the beam width adjustment optical group 20 and the focusing optical group 30 corresponds to the distance between lenses 24 and 32. This distance can be in the range of 25mm to 1000mm, for example, 75mm to 750mm, including a preferred range of 500mm to 750mm.

[0107] The beam width adjustment optics 20 can be configured to adjust the beam width W of the laser beam B while satisfying at least one of the following conditions: - The change in the beam propagation angle of the laser beam B is no greater than 10°: Since the laser beam B is collimated when it reaches the lens 22, this means that, in the exemplary embodiment under consideration, after passing through the beam width adjustment optical group 20, the laser beam B between the lenses 24 and 32 remains convergent or at most slightly divergent with a divergence angle no greater than 10°, or slightly convergent with a convergence angle no greater than 10°.

[0108] - Adjust the distance from the beam width of optical group 20 to the focusing optical group 30 along the optical path of the laser beam (see...) Figure 3 and Figure 5 The ratio of the distance D in the beam width adjustment optics group 20 to the Rayleigh length of the laser beam measured downstream of the beam width adjustment optics group 20 and upstream of the focusing optics group 30 is not greater than 1000, and may not be greater than 60: In the present case, if the distance between the beam width adjustment optics group 20 and the focusing optics group 30 (i.e. the distance between lenses 24 and 32) is, for example, 75 mm, the Rayleigh length of the laser beam B downstream of the beam width adjustment optics group 20 is at least 75 mm, preferably at least 125 mm, and may be at least 25 mm or at least 75 mm.

[0109] The scanning unit 40 includes a pair of XY movable mirrors 42a and 42b with corresponding galvanometers (not shown) for controllably scanning the laser beam B across the working area 13W in a two-dimensional direction. The scanning unit 40 is positioned downstream of both the beam width adjustment optics group 20 and the focusing optics group 30 along the beam path. The movable mirrors 42a and 42b, which can be controlled by the control processing unit 50, are used to guide the laser beam B to the desired position on the workpiece P.

[0110] In the illustrated embodiment, the control processing unit 50 includes a first control module 52 and a second control module 54. The first control module 52 can control the movement of the movable lens 22 in the beam width adjustment optics group 20 and the movement of the movable lens 32 in the focusing optics group 30, so as to change the spot size of the laser beam B, for example, on the working area 13 or the workpiece P, while keeping the focal position F constant, or to change the focal position F (e.g., at a target value of 60 μm) while keeping the spot size of the laser beam constant.

[0111] The second control module 54 can control the movement of the movable lens 22 in the beam width adjusting optics group 20 to adjust the beam width at a position between groups 20 and 30 along the beam path of the laser beam, corresponding to a target value associated with the focusing optics group 30, and particularly a target value associated with the movable lens 32 of the focusing optics group 30. The target value may be, for example, the maximum beam width compatible with the focusing optics group 30 or its current configuration. For example, if the focusing optics group 30 is adapted to receive a laser beam B with a maximum beam width of 20 mm, the second control module 54 can control the movement of the movable lens 22 such that the beam width W2 of the laser beam B does not exceed the maximum value.

[0112] During operation, the laser beam B enters the laser processing apparatus 10 through the laser input unit 12. The beam width adjustment optics group 20 and the focusing optics group 30 can adjust the spot size of the laser beam B (i.e., the beam width of the laser beam B at the focal position F) and readjust the focal position F of the laser beam B, particularly keeping the focal position F constant, so as to keep the focal position F on the working area 13 or on the workpiece P. The scanning unit 40 guides the laser beam B onto the workpiece P, thereby allowing for precise laser processing.

[0113] Figure 2 It shows Figure 1 A schematic diagram of the laser processing device 10, wherein, with Figure 1 In contrast, the movable lens 22 has been moved, specifically upwards in this exemplary case. Therefore, compared to... Figure 1 Compared to the configuration shown, the beam width W2' downstream of the beam width adjustment optics group 20 and upstream of the focusing optics group 30 is reduced, i.e., W2' < W2. Therefore, in Figure 2 The spot size in the configuration (i.e., the beam width at the focal point F of the laser beam) will also be larger than that in the configuration where... Figure 1 The size of the light spot in the configuration.

[0114] If the focusing optics group 30 is not operated, the change in position of the movable lens 22 of the beam width adjusting optics group 20 will result in a reduction in the effective focal length of the entire optical system. Therefore, the focal position F of the laser beam B relative to... Figure 1 The laser beam B has changed direction and is now upstream of workpiece P. Therefore, the laser beam B is defocused on workpiece P.

[0115] Figure 3 The adjustment is shown Figure 2 The optical result of the focal position after the beam width. Figure 3 It shows Figure 1 and Figure 2 A schematic dedicated view of the optical components of the beam width adjustment optics group 20 and the focusing optics group 30, wherein, with Figure 1 and Figure 2 In contrast, the system is arranged horizontally, and for illustrative purposes, the laser beam B is transmitted from left to right instead of vertically. The optical axis is denoted by A. Lenses 22, 24, 32, and 34 are... Figure 1 The positions corresponding to the conditions in the diagram are shown with solid lines, while the positions of lens 22 and... Figure 2 The positions corresponding to the conditions in the diagram are shown with dashed lines. Similarly, for the optical configuration of lens 22 shown with solid lines and the configuration of lens 22 shown with dashed lines, the laser beam is represented by different types of dashed lines. The distance between lenses 24 and 32 is denoted as D.

[0116] Before being altered by lenses 22 and 24 of the beam width adjusting optical group 20, the beam width of the laser beam corresponds to the value W1, and the laser beam is collimated. Then, the beam width adjusting optical group 20 changes the beam width to different values ​​W2 or W2' according to the position of the movable lens 22, where W2' < W2, and the laser beam can be slightly converged between lenses 24 and 32.

[0117] The lens is represented by a solid line. Figure 1 In the corresponding configuration, the focusing optics group 30 focuses the laser beam at a focal point F, which can correspond to a target position on the working area 13 or the workpiece P. Once the movable lens 22 moves from the position indicated by the solid line to the target position... Figure 2 The corresponding position, indicated by the dashed line, and without any compensating movement of the movable lens 32 of the focusing optics group 30, causes the focal position of the laser beam to move from the position indicated by F to the position indicated by F', and the laser beam is no longer focused on the previous target position corresponding to the working area 13 or the workpiece P. According to the invention, this can be avoided by corresponding coordinated movement of the movable lens 32 of the focusing optics group 30, such as... Figure 4 and Figure 5 As shown in the image.

[0118] Figure 4 It shows Figure 1 A schematic diagram of the laser processing device 10, wherein, with Figure 1 In comparison, movable lens 22 has moved upward and movable lens 32 has moved downward. Therefore, compared to Figure 1 Compared to the configuration shown, the beam width W2' (which can be measured when the laser beam B is incident on lens 32) downstream of beam width adjusting optics group 20 and upstream of focusing optics group 30 is reduced, and now slightly converged, i.e., W2' < W2. Therefore, in Figure 4 The spot size in the configuration (i.e., the beam width at the focal point F of the laser beam) will be larger than that in the configuration where... Figure 1 The spot size in the configuration. However, since the focusing optics group 30 and the beam width adjustment optics group 20 work together, the change in effective focal length of the entire optical system caused by the change in the position of the movable lens 22 of the beam width adjustment optics group 20 is compensated by the corresponding change in the effective focal length of the entire optical system. This change causes a change in the position of the movable lens 32 of the focusing optics group 30, so that the focal position F of the laser beam B is relative to... Figure 1 The overall focus remains constant. Therefore, regardless of changes in the spot size, the laser beam B remains focused on the workpiece P.

[0119] Figure 5 It shows Figure 1 and Figure 4A schematic dedicated view of the optical components of the beam width adjustment optics group 20 and the focusing optics group 30, wherein, with Figure 1 and Figure 4 In comparison, the system is horizontally arranged, and for illustrative purposes, with Figure 3 Similar to the previous example, laser beam B propagates from left to right instead of vertically. The optical axis is denoted by A. Lenses 22, 24, 32, and 34 are analogous to... Figure 1 The positions corresponding to the conditions in the diagram are shown with solid lines, while the positions of lenses 22 and 32 are shown with... Figure 4 The positions corresponding to the conditions in the diagram are shown with dashed lines. Similarly, for the optical configurations of lenses 22 and 32 shown with solid lines and the configurations of lenses 22 and 32 shown with dashed lines, the laser beam is represented by different types of dashed lines. The distance between lenses 24 and 32 is denoted as D.

[0120] Before being altered by lenses 22 and 24 of the beam width adjustment optics group 20, the beam width of the laser beam corresponds to a value W1, and the laser beam is collimated. Then, the beam width adjustment optics group 20 changes the beam width to a different value W2 or W2' depending on the position of the movable lens 22, where W2' < W2 and where W2' can be equal to... Figure 2 and Figure 3 The W2' shown is the same, and the laser beam B is slightly converged between 24 and 32. For example, the convergence angle of the laser beam B with beam width W2' after passing through group 20 can be 10° or less.

[0121] In the configuration of lenses represented by solid lines, and Figure 1 Correspondingly, the focusing optics group 30 focuses the laser beam at a focal point F, which can correspond to a target position on the working area 13 or the workpiece P. If the movable lens 22 moves from the position indicated by the solid line to the position indicated by the dashed line, and the movable lens 32 of the focusing optics group 30 moves from the position indicated by the solid line to the position indicated by the dashed line, and... Figure 4 Correspondingly, the focal position F of the laser beam remains constant.

[0122] exist Figure 1 , Figure 2 and Figure 4 In this context, the variation in beam width achieved by the beam width adjustment optical group 20 is only shown at positions between groups 20 and 30. However, a corresponding change in spot size also exists at the focal position F, which is... Figure 6 It is shown in detail in the text. Figure 6 Will correspond to Figure 1 The configured spot size W3 corresponds to Figure 4The beam width is compared with the configured spot size W3', where W3' > W3. Under practical (non-ideal) conditions, the laser beam does not have a point focal point, but rather a given beam width (i.e., "spot size" or "focal diameter") at its focal location. Any change in beam width achieved by the laser processing apparatus 10 is associated with a corresponding change in spot size. Therefore, the beam width adjustment optics 20 can be used to increase or decrease the spot size W3. Figure 1 and Figure 4 In the example shown, the spot size increases from W3 to W3'. In related embodiments, the spot size may be increased to, for example, twice or three times its original size. However, in other related embodiments, the spot size may be reduced to, for example, half or one-third of its original size.

[0123] Figure 6 It shows the result of Figure 1 and Figure 4 The laser processing apparatus 10 achieves the effect of varying the beam width of the laser beam B, especially the effect of varying the beam width of the laser beam B achieved by its beam width adjustment optical group 20 and focusing optical group 30. Figure 6 A shows Figure 4 A schematic side magnified view of the working area 13 of the laser processing apparatus 10, the spot size (i.e. the beam width of the laser beam B at the focal point where it coincides with the upper surface of the workpiece P) is denoted as W3'. Figure 6 B shows Figure 1 A schematic magnified side view of the working area 13 of the laser processing apparatus 10, wherein the spot size (i.e., the beam width of the laser beam B at its focal point where it again coincides with the upper surface of the workpiece P) is denoted as W3, although in this case it has a larger value W3' > W3. In other cases, W3' < W3 can be achieved.

[0124] Figure 7 Provided Figure 6 A schematic top view of the working area 13, for illustrative purposes and not for limitation, shows a workpiece P with a hexagonal profile arranged in the working area 13 and laser-processed by a laser beam B. The laser beam B is focused on the upper surface of the workpiece P. Figure 7 In A, with Figure 4 and Figure 6 A corresponds to a spot size or focused diameter of W3', and in Figure 7 In B, with Figure 1 and Figure 6 B corresponds to W3, where the spot size or focusing diameter is W3.

[0125] The combination of the beam width adjustment optics group 20 and the focusing optics group 30 allows for rapid and precise control of both the beam width and the focal position of the laser beam, facilitating precise laser processing.

[0126] Figures 1 to 7 An exemplary illustration shows the beam width adjustment optics 20 used to reduce the beam width W2 < W1, i.e., to increase the spot size W3' > W3. However, the beam width adjustment optics 20 can be used to obtain a laser beam B with a larger beam width (W2 > W1). For other applications, the beam width adjustment optics 20 can be used to obtain a laser beam B with a smaller beam width (W2 < W1), for example, for more precise and localized laser processing. In any case, regardless of whether the beam width or spot size is increased or decreased, the laser processing apparatus 10 of the present invention allows the focal position F of the laser beam B to remain constant while changing the spot size, and / or the spot size to remain constant while changing the focal position F. For a given focal position F, the minimum spot size W3 achievable by the laser processing apparatus 10 of the present invention can be determined by the focusing optics 30, which can be configured to receive a given maximum beam width W2.

[0127] Those skilled in the art know how to select the optical characteristics of the lenses in optical groups 20 and 30. For example, for a laser beam B with a beam width W1 of 4 mm, if the movable lens 22 is a convex lens with an effective focal length of +300 mm, and the fixed lens 24 is a concave lens with an effective focal length of -250 mm, and the distance between lenses 22 and 24 is 50 mm, the distance between lenses 24 and 32 is 25 mm, and the focusing optical group 30 is configured to achieve an effective focal length of 60 mm, then in Figure 5 The transition from the configuration shown in solid lines to the configuration shown in dashed lines requires moving lens 22 upwards by 100mm and increasing the focal length of focusing optical group 60 to 66.7mm.

[0128] The control processing unit 50 can also control the laser beam B input to the laser processing apparatus. For example, the control processing unit 50 can be configured to adapt the laser power of the laser beam B as a function of the beam width. For example, if the beam width adjusting optics 20 is configured to increase the beam width W2 > W1, and thus reduce the spot size, the control processing unit 50 can correspondingly increase the laser power of the laser beam B, so that the laser power density remains constant despite the increase in beam width. Similarly, if the beam width adjusting optics 20 is configured to decrease the beam width W2 < W1, and thus increase the spot size, the control processing unit 50 can correspondingly decrease the laser power of the laser beam B, so that the laser power density remains constant despite the decrease in beam width.

[0129] Figure 8 A schematic diagram of a laser processing apparatus 10 according to some embodiments of the present invention is shown. In this example, the laser processing apparatus includes two laser input sections 12-1 and 12-2, each for inputting a corresponding laser beam B1 and B2. The first laser beam B1 is collimated by an optional first collimating optical system 16-1, which can correspond to a collimating lens, and the second laser beam B2 is collimated by an optional second collimating optical system 16-2, which can correspond to a collimating lens. For example, if collimation is not required when the individual laser beams enter the laser processing apparatus, one or both of the optional collimating optical systems 16-1 and 16-2 can be omitted.

[0130] Both the first laser beam B1 and the second laser beam B2 are guided toward the beam width adjusting optical group by a dichroic element 18 arranged within the housing 11, partially overlapping along the same optical path. This dichroic element 18 is transmissive to the first beam B1 and reflective to the second beam. (As described above for...) Figures 1 to 7 As described in the exemplary embodiments, the beam width adjustment optics group 20, the focusing optics group 30, and the scanning unit 40 are operable.

[0131] In this exemplary embodiment, the laser processing apparatus 10 further includes an optional beam adjustment element 19, which may be or include a diffractive optical element for adjusting the beam shape and / or beam intensity distribution of the second laser beam B2. For example, the beam adjustment element 19 may cause the laser beam B2 to be transmitted downstream to a beam width adjustment optical group 20 having a circular cross-section and a Gaussian beam intensity distribution. In other related embodiments, an optional second beam adjustment element may be arranged in the beam path of the first laser beam B1 (specifically upstream of the dichroic element 18) for adjusting the beam shape and / or beam intensity distribution of the first laser beam B1.

[0132] Figure 8 The processing control unit is not shown, but it may be present to control the beam width adjustment optics 20, the focusing optics 30, and the scanning unit 40.

[0133] - exist Figure 8 In the configuration shown, the beam width adjustment optical group 20 can be configured to adjust the beam width of one or both of the first laser beam B1 and the second laser beam B2, while satisfying at least one of the following conditions: - The variation in the beam propagation angle of laser beams B1 and / or B2 is no greater than 10°.

[0134] - Adjust the distance from the beam width optical group 20 to the focusing optical group 30 along the optical path of the laser beam B1 or B2 (see...) Figure 3 and Figure 5 The ratio of the distance D in the beam width adjustment optics group 20 to the Rayleigh length of the laser beam B1 or B2 measured downstream of the beam width adjustment optics group 20 (specifically downstream of the beam width adjustment optics group 20 and upstream of the focusing optics group 30) is not greater than 1000, and may not be greater than 60.

[0135] exist Figure 8 In the illustrated configuration, the first laser beam B1 and the second laser beam B2 can have one or more of the following: different beam widths, different wavelength ranges, different beam shapes, and different intensity distributions. For example, the first laser beam B1 can correspond to a laser beam with a circular cross-section having a Gaussian intensity distribution and a beam width of 20 mm in a first wavelength range of 1030 nm to 1090 nm, while the second laser beam B2 can have a top-cap cross-section that can be triggered by an optional beam adjustment element 19, having a Gaussian intensity distribution and a beam width of 15 mm in a second wavelength range of 515 nm to 540 nm. If required by the corresponding wavelength, the first laser input unit 12-1 and / or the second laser input unit 12-2 can include an additional focusing optics group, which includes at least one movable lens.

[0136] In this example and other examples, the first laser beam B1 and the second laser beam B2 can be used to sequentially or simultaneously laser process different areas of the working area or workpiece, and can also be used to sequentially or simultaneously laser process a single area of ​​the working area or workpiece.

[0137] For example, if the second laser beam B2 has a larger beam width than the first laser beam B1, then at a given scanning speed, the second laser beam B2 can achieve the desired melting in a shorter time compared to the first beam B1. The second laser beam B2 can use a larger spot size to help obtain a uniform molten pool, reduce the formation of welding sparks, and avoid the formation of so-called keyholes and so-called spheroidization effects. Meanwhile, the first laser beam B1 can be set to have a smaller spot size and can be used for laser processing of the leading edge region between different sections of the workpiece, as well as for laser processing of the outer contour of the workpiece P with greater laser precision.

[0138] The advantages of the laser processing apparatus 10 according to the invention are particularly evident when using a laser beam with a given intensity distribution and / or beam shape. If the spot size of the laser beam increases and the corresponding defocusing of the laser beam is not compensated, the intensity distribution of the laser beam may be distorted or lost, and instead, a laser spot with an undefined intensity distribution will have to be used for laser processing. The laser processing apparatus 10 according to the invention can advantageously prevent this situation due to the coordination between the beam width adjusting optics group 20 and the focusing optics group 30.

[0139] Figure 9 , Figure 10 and Figure 11 Schematic flowcharts of various methods according to embodiments of the present invention are shown. These methods can be implemented by the control processing unit 50 of the laser processing apparatus of the present invention, or by any other general processing unit functionally coupled to or integrated into the laser processing apparatus 10 according to the present invention.

[0140] For example, in laser powder bed fusion or laser welding processes, method 100 can be performed to laser process workpieces, particularly for welding bipolar plates of battery cells and / or combustible batteries.

[0141] Method 100 includes a process 102 of inputting at least one laser beam B into the laser processing apparatus 10 via at least one laser input section 12. Figures 1 to 7 In the previously seen exemplary embodiment, a laser beam B is input into the laser processing apparatus 10 via a corresponding laser input unit 12. Figure 8 In an exemplary embodiment, the first laser beam B1 and the second laser beam B2 are input into the laser processing apparatus 10 through their respective laser input sections 12-1 and 12-2. Alternatively, more than two laser beams may be input into the laser processing apparatus.

[0142] The laser beam input to the laser processing apparatus 10 is preferably collimated before entering the laser processing apparatus or after entering the laser processing apparatus (preferably before the beam width adjustment optical group 20 and the focusing optical group 30) or can be collimated by a corresponding collimating optical system.

[0143] like Figure 9 and Figure 11 As shown, method 100 may further include a process 104 of operating the beam width adjustment optics 20 of the laser processing apparatus 10 to adjust the beam width of at least one laser beam B. If process 106 is not performed (i.e., if the focusing optics 30 is not operated), adjusting the beam width (or spot size) of the laser beam may include increasing the beam width (or spot size) by, for example, 2 times, 3 times, 4 times, 5 times or more, or decreasing the beam width (or spot size) by, for example, 2 times, 3 times, 4 times, 5 times or more, depending on the desired laser application.

[0144] like Figure 10 As shown, method 100 may further include a process 106 of operating the focusing optics 30 of the laser processing apparatus 10 to adjust the focal position of at least one laser beam B, particularly if process 104 is not performed (i.e., if the beam width adjustment optics 20 is not operated).

[0145] like Figure 11As shown, method 100 may further include Figure 9 The process 104 and the process 108 of operating the laser processing apparatus 10 to adjust the focal position and spot size of at least one laser beam B by adjusting the beam width adjustment optics 20 and the focusing optics 30.

[0146] Procedures 104 and 108 can be executed sequentially or simultaneously. Procedure 104 can exist without procedures 106 and 108 (see [link to relevant documentation]). Figure 9 Process 106 can exist without processes 104 and 108 (see...) Figure 10 ), or both processes 104 and 108 can exist (see Figure 11 By combining the beam width adjustment optics group 20 and the focusing optics group 30, processes 104 and 106 can be executed simultaneously or sequentially to adjust the spot size and focal position of the laser beam. For example, processes 104 and 106 can be executed to change the spot size while keeping the focal position F of the laser beam B constant, or to adjust the focal position F of the laser beam B while keeping the spot size of the laser beam B constant.

[0147] Method 100 also includes a process 112 of outputting a laser beam through the laser output section 14 of the laser processing apparatus 10. The laser beam can then be used for laser processing of the workpiece P.

[0148] Preferably, the method may include an optional process 110 of using the scanning unit 40 of the laser processing apparatus to scan the laser beam to controllably guide the laser beam to one or more target locations of the workpiece being laser processed or one or more target locations of the working area.

[0149] When one or more laser beams B1 and B2 are input into the laser processing device through their respective laser input units 12-1 and 12-2, the beam width is adjusted by the beam width adjustment optical group 20, the focal point position F is adjusted by the focusing optical group 30, and the beams are output through the laser output unit 14 and then used for laser processing. Different laser beams B1 and B2 can have different beam widths, different wavelength ranges, different beam shapes, and different intensity distributions.

[0150] Although preferred exemplary embodiments have been shown and described in detail in the accompanying drawings and the foregoing description, these embodiments should be considered merely exemplary and not as limiting of the invention. It should be noted that only preferred exemplary embodiments have been shown and described, and all variations and modifications that are currently or will be within the scope of the invention as defined in the claims should be protected.

Claims

1. A laser processing device (10), comprising: A laser input section (12) for receiving a laser beam (B) and a laser output section (14) for outputting the laser beam (B). An optical system for the laser beam between the laser input section (12) and the laser output section (14) includes: A beam width adjustment optical assembly (20) for adjusting the beam width of the laser beam (B), wherein the beam width adjustment optical assembly (20) includes at least two lenses (22, 24), and the at least two lenses (22, 24) of the beam width adjustment optical assembly (20) include at least one movable lens (22) for adjusting the beam width of the laser beam (B); and A focusing optical group (30) has an adjustable focal length, wherein the focusing optical group (30) is arranged between the beam width adjustment optical group (20) and the laser output unit (14) along the beam path of the laser beam (B), and includes at least two lenses (32, 34), wherein the at least two lenses (32, 34) of the focusing optical group (30) include at least one movable lens (32). The optical system is configured to adjust the focal position of the laser beam and the spot size corresponding to the beam width of the laser beam at the focal position (F); and The beam width adjustment optical group (20) is configured to be used for at least one of the following: - Ensure that the absolute value of the beam propagation angle of the laser beam (B) changes by no more than 10°; and - The ratio of the distance along the optical path of the laser beam (B) from the beam width adjustment optics group (20) to the focusing optics group (30) to the Rayleigh length of the laser beam (B) measured downstream of the beam width adjustment optics group (20) is not greater than 1000.

2. The laser processing apparatus (10) according to claim 1 further includes: The first control module (52) is used to control the movement of at least one movable lens of the beam width adjustment optical group (20) and the movement of at least one movable lens of the focusing optical group (30) to change the spot size of the laser beam (B) while keeping the focal position (F) of the laser beam (B) constant.

3. The laser processing apparatus (10) according to claim 1 further includes: The second control module (52) is used to control the movement of at least one movable lens of the beam width adjustment optical group (20) and the movement of at least one movable lens of the focusing optical group (30) to change the focal position (F) of the laser beam (B) while keeping the spot size of the laser beam (B) constant.

4. The laser processing apparatus (10) according to claim 1 further includes: A third control module (54) is used to control the movement of at least one movable lens of the beam width adjustment optics group (20) to adjust the beam width of the laser beam (B) to a target value associated with the focusing optics group (30).

5. The laser processing apparatus (10) according to claim 1 further includes: A scanning unit (40) is used to scan the laser beam (B) across the working area (13) in a two-dimensional direction, wherein the scanning unit (40) is arranged downstream of the beam width adjustment optics group (20) and the focusing optics group (30) along the beam path of the laser beam (B).

6. The laser processing apparatus (10) according to claim 1 further includes: At least one collimating optical system (16) is used to collimate the laser beam (B) upstream of the beam width adjusting optical group (20).

7. The laser processing apparatus (10) according to claim 1 further includes: At least one beam adjustment element (19) is used to adjust at least one of the beam shape and beam intensity distribution of the laser beam (B) upstream of the beam width adjustment optics group (20).

8. The laser processing apparatus (10) according to claim 7, wherein, The at least one beam adjustment element (19) is at least one diffractive optical element or includes at least one diffractive optical element.

9. The laser processing apparatus (10) according to claim 1 further includes: At least one dual-color element (18) is arranged upstream of the beam width adjustment optical group (20), wherein the at least one dual-color element (18) is at least partially transparent to a first laser beam (B1) input into the laser processing apparatus (10) through a first laser input section (12-1) and output from the laser processing apparatus (10) through a laser output section (14), and is at least partially reflective to a second laser beam (B2) input into the laser processing apparatus (10) through a second laser input section (12-2) and output from the laser processing apparatus (10) through a laser output section (14).

10. The laser processing apparatus (10) according to claim 1, wherein, The laser input unit (12) is configured to input a collimated laser beam.

11. A method of operating the laser processing apparatus (10) according to claim 1 to laser process a workpiece (P), the method comprising: At least one laser beam (B) is input into the laser processing apparatus (10) through at least one laser input section (12); Operate the beam width adjustment optics (20) of the laser processing apparatus (10) to adjust the beam width of the at least one laser beam (B); or Operate the focusing optics group (30) of the laser processing apparatus (10) to adjust the focal position (F) of the at least one laser beam (B); or Operate the beam width adjustment optics (20) of the laser processing apparatus (10) to adjust the beam width of the at least one laser beam (B), and operate the beam width adjustment optics (20) and the focusing optics (30) of the laser processing apparatus (10) to adjust the focal position (F) of the at least one laser beam (B) and the spot size corresponding to the beam width (W) of the laser beam (B) at the focal position (F); and The at least one laser beam (B) is output through the laser output section (14) of the laser processing device (10). The beam width of the at least one laser beam (B) is adjusted by the beam width adjusting optical group (20) while satisfying at least one of the following: - The absolute value of the beam propagation angle of the laser beam (B) changes by no more than 10°; - The ratio of the distance along the optical path of the laser beam from the beam width adjustment optics to the focusing optics to the Rayleigh length of the laser beam measured downstream of the beam width adjustment optics is no greater than 1000.

12. The method according to claim 11, wherein, Operate the beam width adjustment optics (20) and the focusing optics (30) of the laser processing apparatus (10) to increase or decrease the spot size of the at least one laser beam (B) by a factor of two or more.

13. The method according to claim 11, wherein, Operate the beam width adjustment optics (20) and the focusing optics (30) of the laser processing apparatus (10) to increase or decrease the spot size of the at least one laser beam (B) by 5 times or more.

14. The method according to claim 11, wherein, Operate the beam width adjustment optics group (20) and the focusing optics group (30) to change the beam width (W) or the spot size of the at least one laser beam (B) while keeping the focal position (F) of the at least one laser beam (B) constant, or to change the focal position (F) of the at least one laser beam (B) while keeping the beam width of the at least one laser beam (B) constant.

15. The method according to claim 11, wherein, Operate the beam width adjustment optics group (20) and the focusing optics group (30) to change the beam width (W) or the spot size of the at least one laser beam (B) while keeping the focal position (F) of the at least one laser beam (B) constant, or to change the focal position (F) of the at least one laser beam (B) while keeping the spot size of the at least one laser beam (B) constant.

16. The method according to claim 11, wherein, The at least one laser beam (B) is a collimated laser beam (B) when it enters the laser processing apparatus (10) through the at least one laser input section (12).

17. The method according to claim 11, wherein, The workpiece (P) is laser-processed in a laser powder bed fusion process.

18. The method according to claim 11, wherein, The workpiece (P) is laser-processed in a laser welding process for welding bipolar plates of a battery cell or a combustible battery.

19. The method according to claim 11, wherein, The method further includes: A first laser beam (B1) is input into the laser processing apparatus (10) through the first laser input section (12-1), and a second laser beam (B2) is input into the laser processing apparatus (10) through the second laser input section (12-2). Operate the beam width adjustment optics (20) of the laser processing apparatus (10) to adjust the beam width of at least one of the first laser beam (B1) and the second laser beam (B2); or Operate the focusing optics group (30) of the laser processing apparatus (10) to adjust the focal position (F) of at least one of the first laser beam (B1) and the second laser beam (B2); or Operate the beam width adjustment optics (20) of the laser processing apparatus (10) to adjust the beam width of at least one of the first laser beam (B1) and the second laser beam (B2), and operate the beam width adjustment optics (20) and the focusing optics (30) of the laser processing apparatus (10) to respectively adjust the focal position (F) of at least one of the first laser beam (B1) and the second laser beam (B2) and the spot size of at least one of the first laser beam (B1) and the second laser beam (B2) corresponding to the beam width (W) of at least one of the first laser beam (B1) and the second laser beam (B2) at the focal position (F); and The first laser beam (B1) and the second laser beam (B2) are output through the laser output section (14) of the laser processing device (10).

20. The method according to claim 19, wherein, The first laser beam (B1) and the second laser beam (B2) satisfy at least one of the following conditions: The first laser beam (B1) and the second laser beam (B2) have different beam widths or different spot sizes; The first laser beam (B1) and the second laser beam (B2) have different beam widths and different spot sizes; The first laser beam (B1) and the second laser beam (B2) have different wavelength ranges; The first laser beam (B1) and the second laser beam (B2) have different beam shapes; The first laser beam (B1) and the second laser beam (B2) have different beam intensity distributions.

21. The method according to claim 11, comprising operating the beam width adjustment optics (20) and the focusing optics (30) of the laser processing apparatus (10) for any of the following: Adjust the spot size of the first laser beam (B1) or the second laser beam (B2); While keeping the focal position of the first laser beam (B1) constant, the spot size of the first laser beam (B1) is changed; While keeping the focal position of the second laser beam (B2) constant, the spot size of the second laser beam (B2) is changed; While keeping the spot size of the first laser beam (B1) constant, the focal position of the first laser beam (B1) is changed; and While keeping the spot size of the second laser beam (B2) constant, the focal position of the second laser beam (B2) is changed.

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