Laser processing system for processing workpiece by means of output laser beam

Abstract

The invention relates to a laser machining system (100) for machining a workpiece (42) by means of an output laser beam (3), comprising a laser radiation source (50), an optical device (10), a feed device (60) and a control device (70).

Description

Technical Field

[0001] The invention relates to a laser processing system for processing a workpiece by means of an output laser beam, comprising a feed device for feeding the workpiece relative to an optical device of the laser processing system. Background Art

[0002] Such a laser processing system is known, for example, from DE 37 11 905 A1. In the laser processing system therein, an optical device having a polygon wheel is used for laser processing a material strip that is moved relative to the optical device.

[0003] With such laser processing systems from the prior art, a relative movement of the material web with respect to the optical device can be compensated by correspondingly moving the polygon wheel.

[0004] Purpose of the Invention

[0005] The object of the present invention is to provide an improved laser machining system for machining a workpiece which is moved relative to an optical device of the laser machining system, which laser machining system is in particular more flexible and provides a better machining quality than is the case in the prior art. Summary of the Invention

[0006] This object is achieved by a laser processing system according to claim 1. A laser processing system for processing a workpiece by means of an outgoing laser beam is proposed, the laser processing system comprising a laser radiation source for generating an input laser beam. Furthermore, the laser processing system comprises an optical device for converting the input laser beam into an outgoing laser beam for processing the workpiece, the outgoing laser beam propagating in a propagation direction and having a beam cross-section extending along a long axis of the optical device in a working area, the optical device comprising: long-axis focusing optics for focusing a beam path within the optical device between the input laser beam and the outgoing laser beam along the long axis; a long-axis scanner component for scanning the beam path along the long axis, at least with a long-axis scanning direction component; short-axis focusing optics for focusing the beam path along a short axis of the optical device extending perpendicular to the long axis; optional short-axis beam shaping optics for beam shaping the beam path along the short axis; and a short-axis scanner component for scanning the beam path along the short axis, at least with a short-axis scanning direction component. In addition, the laser processing system has: a feeding device for feeding the workpiece relative to the optical device in a feeding direction; and a control device for synchronizing the scanning of the beam path along the long axis scanning direction component with the scanning of the beam path along the short axis scanning direction component.

[0007] In particular, the synchronization by means of the control device can be arranged to compensate for relative movements between the workpiece and the optical device caused by feeding the workpiece in the feed direction by scanning the beam path with the short-axis scanner element.

[0008] Therefore, according to the present invention, a solution is provided in which separate scanner components are provided for the short axis and the long axis, but these components are synchronized with one another in their scanning movements, in particular in such a way that compensation for relative movements between the workpiece and the optical device can be flexibly performed by means of corresponding control commands of the short-axis scanner component by the control device, wherein the scanning performed with the long-axis scanning direction component is not substantially affected by this. In particular, compensation can be performed solely by scanning with the short-axis scanning direction component, so that the short-axis scanning also serves only to compensate for relative movements. In addition to the flexible responsiveness of the laser processing system according to the present invention, the present invention also enables better imaging of the beam cross section or beam profile, which in turn improves the processing and, therefore, the overall quality of the laser-processed workpiece.

[0009] In particular, a beam profile with a preferred direction can be used, which is particularly precisely positioned relative to the workpiece and aligned with the preferred processing direction relative to the workpiece. For continuous processing on the workpiece along a line, in particular a preferred processing line, the optical device is aligned with the long-axis scanning direction component, in particular so that it is aligned with the long axis, preferably parallel to the preferred processing line of the workpiece. If the relative movement between the optical device and the workpiece deviates from the long-axis direction during laser processing, this can be advantageously compensated by a specially superimposed short-axis scanning movement in the short-axis scanning direction component, in particular so that it is aligned with the short axis, wherein this short-axis scanning movement can preferably be set independently of the long-axis scanning movement, as explained in more detail below. Preferably, the short-axis scanner component is positioned in the corresponding short-axis far-field region and is separated from the long-axis scanner component in the beam propagation direction.

[0010] The short axis and the long axis of the optical device, and thus the short axis and the long axis of the optics of the optical device, are particularly perpendicular to one another. In the case of the proposed astigmatic optical device, both the size and shape of the beam cross section can change during propagation. In the working area on the workpiece, the output laser beam can have an elliptical beam profile, particularly with an aspect ratio of the short axis to the long axis of, for example, at least 1:3, particularly at least 1:5, and even more particularly 1:10, such that a linear beam cross section extending along the long axis LA is observed. In particular, linear optics extending in the spatial direction of the long axis can be used for focusing in the spatial direction of the short axis.

[0011] Components, (spatial) directions, areas, or other information, such as optical devices, are assigned "KA" for the minor axis or "LA" for the major axis to indicate their relevance to the respective axis, e.g., the optical effect of the optical device with respect to the minor or major axis, and thus to distinguish between the minor and major axes. Components are preferably aligned with their preferred direction in the minor or major axis spatial direction. The beam cross section, also referred to as the beam profile (particularly with respect to its maximum extent), typically extends in the major axis spatial direction, very particularly linearly, at least in its broadest sense. However, depending on the configuration, other extents of the beam cross section with respect to its length in directions other than the major axis spatial direction are also conceivable. In this context, the beam path refers to the laser beam within the optical device, i.e., between the input, referred to as the input laser beam, and the output, referred to as the output laser beam, of the optical device. The far-field region of the beam path can be located within the optical device, while the output laser beam or the near-field region of the beam path, on the other hand, is connected to the work area and, in particular, is located in or on a workpiece in the work area.

[0012] The long-axis focusing optical element and / or the short-axis focusing optical element are preferably designed as astigmatic / anamorphic optical components or component groups, possibly as cylindrical optics, i.e., their optical function is limited to the long-axis spatial direction or the short-axis spatial direction. The long-axis scanner component and the short-axis scanner component can, for example, each be a mirror scanner with a galvanometer drive and / or a rotating polygon mirror scanner.

[0013] The feed device can be, for example, a conveyor belt or a rotating guide roller, on which a particularly continuous workpiece or workpiece roll is provided in front of the optical device. The workpiece roll can be processed as a workpiece by the output laser beam, for example, cut into slices.

[0014] The control device may be a cross-component control device of the laser processing system and may be provided in one or more components of the laser processing system, for example as part of the optical device, in particular the short-axis scanner component.

[0015] Although reference is made here to one input laser beam and one output laser beam, it is conceivable and possible that the optical device generates a plurality of output laser beams or partial beams (from one or more input laser beams) which are parallel or which are displaced in parallel in the working area, in particular in the spatial direction of the minor axis. The output laser beams or partial beams can be offset in position and / or angle in the working area. This can be achieved by partial beam profiles separated in the spatial direction of the minor axis or by means of multi-beam interference of partial beam profiles with an angular offset of the minor axis that overlap in the working area. The use of partial beams makes it possible to increase the width of the output laser beam or to perform parallel line processing with an offset in the spatial direction of the minor axis. For example, this type of parallel line processing can be used for cutting electronic chips, multi-line engraving of electrical steel sheets, rust removal of metal surfaces or structuring of battery foils.

[0016] In particular, the long-axis scanner component and the short-axis scanner component can be scanner components that operate independently of one another. This functional independence of the scanner components, which can be separate components or functionally independent of one another, provides maximum flexibility for positioning the output beam in the processing area and, in particular, for compensating for relative movements between the workpiece and the optical device caused by the feeding of the workpiece.

[0017] Furthermore, in particular, the long-axis scanner component can be configured to scan the beam path or the output laser beam in a preferred processing direction, in particular a preferred linear direction, parallel to the long axis, such that a first angle α>0° exists between the long-axis scanning direction or preferred processing direction and the feed direction. In particular, the first angle α can be 0°<α<180°, for example, α=90°. The preferred processing direction of the beam profile can be oriented, in particular, in the long-axis direction and / or the short-axis direction.

[0018] More specifically, the first angle α may be >90°. In case of such deviation of the preferred machining direction from a straight line orthogonal to the feed direction, the long axis scanning direction with partial compensation for relative movement is set to reduce the required scanning field, the required scanning speed, etc.

[0019] Additionally, the long-axis scanner component may be configured for at least an average long-axis scanning velocity v LA =B b / (t s ·sin(α))+v R cos(α), and / or the short-axis scanner component may be configured for at least an average short-axis scanning velocity (in the coordinate system of the arrangement) v KA =v r sin(α), where B bis the machining width of the workpiece perpendicular to the feed direction, t s For processing length B l =B b / sin(α) processing time (from the start to the end of processing of the processing length during the scanning operation), and v R Is the feed speed in the feed direction. The effective scanning speed is related to the relative movement between the laser beam and the workpiece, so the effective scanning speed can also be called the processing speed. Through such a design, it is possible to achieve straight-line continuous processing of the workpiece, especially the minimum line width and / or edge steepness of the effective beam cross section (while maintaining other parameters). The effective long-axis scanning speed is basically related to the processing effect, while the short-axis scanning speed is specifically used only to compensate for the relative movement. The quotient of the processing width and the processing time B b / t s can be interpreted as the (average) machining speed v perpendicular to the feed direction B =B b / t S =B l sin(α) / t S The workpiece is processed during the processing time t s Feed B S represents the minimum time period of a machining operation in the feed direction (assuming that multiple partial beams are not used simultaneously and the system dead time is 0%, ie the next machining operation starts immediately after the previous machining operation ends).

[0020] In particular, the long-axis scanner component can be configured for a long-axis scan field length s LA ≥B b / sin(α)+B s cos(α), and / or the short axis scanner component can be configured for a short axis scan field width s KA ≥B s sin(α), where B s During scanning, especially during processing time t s The length of the sweep during the period, and where B s is oriented in particular in the feed direction. In this case, machining can be performed with the optical device without a deviation perpendicular to the feed direction. In other cases, the information about the scanning area relates in particular to the center of the beam profile.

[0021] Furthermore, the optical device can be designed such that the beam cross section is formed by a multi-point profile. Due to the astigmatic focusing of the optical device, such a multi-point profile is stretched in the direction of the generated line and thus produces a beam cross section on the workpiece.

[0022] It is possible to specify a multi-point profile with points distributed along both the minor axis and the major axis. Alternatively, it is also possible to align points of a multi-point profile only along the minor axis or only along the major axis. Points can also be arranged to overlap, as described in more detail below.

[0023] In particular, a multi-point profile with a line orientation of the beam cross section resulting from the astigmatic focusing of the optical system can be set to have an angle (Anstellwinkel) > 0° relative to the long-axis scanning direction component (in particular, coinciding with the long axis). This option makes it easier to ensure z-position tolerances by restricting the machining to a short region in the feed direction. For example, in roll-to-roll applications, machining can also be performed in the region where the workpiece rests on the deflection rollers.

[0024] Furthermore, the control device can be configured to match the laser power of the output laser beam to the beam movement speed and / or the scanning speed of the beam path of the output laser beam over the workpiece. By matching the laser power to the effective scanning speed relative to the workpiece, reproducible processing results can be achieved despite typical fluctuations. This has the benefit of improved reproducibility and increased flexibility and tolerance.

[0025] The laser radiation source can also be a pulsed laser radiation source, in particular an ultrashort pulsed laser radiation source. Pulsed laser radiation sources enable extensive control over the laser processing, in particular with regard to the generated heat buildup. The typical spatial and temporal gradients of the effect to be achieved in the workpiece are relevant here. Typically, a threshold intensity or threshold energy density is required, and the intensity and energy density must be selected within a suitable window. With CW laser radiation sources, such a threshold value or range may not usually be achievable, or can only be achieved with difficulty by selecting appropriate power, beam shape, and beam dynamics.

[0026] However, in this application, pulsed laser radiation sources have proven to be advantageous and preferred over CW laser radiation sources. They allow for machining operations that can be precisely modulated in terms of position in the scanning direction. Ultrashort-pulsed laser radiation sources are particularly advantageous when intensity thresholds are present or when effects are induced by dynamic thermomechanical mechanisms. Even with high beam dynamics, they can be operated with high positional accuracy, with only negligible beam movement on the workpiece during the pulse duration.

[0027] The control device can be configured to match the pulse repetition frequency to the effective scanning speed of the long-axis scanner component. This means that the laser pulse parameters, energy per unit length, and overlap or modified distance can be maintained across the workpiece. It can also match the varying speeds within the scan area, resulting in deflection-dependent velocities across the workpiece.

[0028] The control device can also be configured for position-synchronized pulse triggering along the longitudinal axis. This means that the laser pulses are triggered based on specific positions along the longitudinal axis, i.e., the laser pulses are synchronized with these positions. This enables more precise matching of the repetition rate, since the position can also be controlled. Furthermore, position-synchronized pulse triggering is suitable for increased dynamics, for example, even when accelerating machining using a galvanometer scanner as a longitudinal scanner component.

[0029] Furthermore, the control device can be configured to select laser processing parameters for positional adaptation along the longitudinal axis. This means that the laser processing parameters are selected based on the position along the longitudinal axis. This allows, for example, the laser processing parameters to be adapted to deflection-related beam properties, such as deformation, by adapting the pulse energy and repetition rate. This also enables adaptation to workpiece characteristics or processing specifications that vary in the scanning direction. For example, other laser processing parameters can be used to cut in edge coatings or at the intersection of vertically oriented ablation lines.

[0030] The long-axis scanner component can also carry the measurement beam path of the optical sensor system. This means that the long-axis scanner component can also be used for diagnostics, in particular before, during, and / or after processing. Advantageously, correlation with the beam path can be used for processing. Possible options include, for example, pre-position detection, distance and / or depth detection (before and / or after), in particular for adapting laser processing parameters in the current or subsequent pass; process monitoring, such as, in particular, simultaneous emission, reflection, OCT, WIM, etc.; and / or detection of processing stages, such as, for example, by means of spectroscopy, for example, for the implementation of backside coatings.

[0031] The optical device can also further comprise short-axis relay optics for imaging a short-axis far-field region of the beam path along the short axis within the optical device. Thus, such an optical device enables the implementation of an astigmatic optical concept with particularly strong, in particular high-resolution, focusing in the short axis (KA) or the short axis spatial direction, and a large working field in the long axis (LA) or the long axis spatial direction. This enables improved control of the beam profile within the expanded working field in the short axis spatial direction, in particular by integrating an additional optical function between the scanner component that scans at least in the long axis spatial direction as a scanning direction component and the short axis focusing optics by means of the short-axis relay optics and / or possibly one or more further short axis optics, which function supports influencing the angular and / or spatial distribution in the short axis far-field region corresponding to the working region of the output laser beam.

[0032] In particular, the relay optics ensure short-axis far-field imaging between the short-axis scanner components, which specifically images a short-axis far-field region that is associated with the working area via the short-axis focus and is positioned after the (long-axis) scanner component, backward in the beam propagation direction into a region closer to the beam input, into a corresponding short-axis far-field region. The corresponding short-axis far-field region is preferably located in front of the long-axis focus and / or the long-axis scanner component. The short-axis beam profile in the region of the corresponding short-axis far-field region is particularly influenced by the short-axis beam shaping optics. The short-axis scanner component is particularly located in the region of the corresponding short-axis far-field region and preferably substantially influences the short-axis angle distribution in this region. The components for short-axis far-field imaging or the short-axis relay optics are preferably arranged between the short-axis focus and the long-axis focus and / or the long-axis scanner component. The short-axis far-field imaging preferably includes further components, which are preferably arranged in front of the long-axis scanner component. The short-axis relay optics preferably include a 4f telescope with cylindrical optics. For example, the short axis relay optics may be designed in a known manner using two correspondingly aligned aspheric lenses or optics, also referred to herein as relay lenses. In particular, the short axis relay optics may be short axis 4f relay optics.

[0033] In particular, the short-axis relay optics may be arranged in the beam path after the short-axis beam shaping optics.The short-axis relay optics enable control of the short-axis far field after beam shaping by the short-axis beam shaping optics.

[0034] The short axis focusing optics can also be arranged in the beam path after the short axis relay optics. This enables the short axis focusing optics to focus the output laser beam from the short axis far field region of the short axis relay optics directly onto the workpiece in the working area.

[0035] The short-axis focusing optics can also, and preferably are, arranged in the beam path behind the long-axis scanner assembly. This enables the short-axis focusing optics to focus the outgoing laser beam directly onto the workpiece in the work field. In particular, the distance between the short-axis focusing optics and the work area is therefore less than the distance between the long-axis scanner assembly and the work area; for example, the distance between the short-axis focusing optics and the work area can be half or less of the distance between the long-axis scanner assembly and the work area. The aperture of the short-axis focusing optics preferably extends to at least half the length of the long-axis work area in the work area.

[0036] The short-axis scanner component can also and preferably be arranged in the beam path before the long-axis scanner component. This means that long-axis beam shaping may already be performed in or before the corresponding short-axis far-field region.

[0037] The long-axis focusing optics can also be arranged in the beam path after the long-axis scanner component. Alternatively, the long-axis focusing optics can be arranged in the beam path in front of the long-axis scanner component. In other words, even when the long-axis scanner component is arranged in front of the short-axis focusing optics, the long-axis scanner component can advantageously be used as a rear (objective lens) scanner component with respect to the long-axis spatial direction.

[0038] The optical device may also include long-axis beam shaping optics for beam shaping the beam path along the long axis. Like the possible additional short-axis beam shaping optics, the long-axis beam shaping optics may include or provide, for example, multiplexing, mapping, superimposed scanning movements, and / or additional short-axis beam shaping or long-axis beam shaping functions. Multiple input beams may also be provided. In this case, the long-axis beam shaping optics can align the generated partial beams with one another.

[0039] The long-axis beam-shaping optics can be arranged in the beam path ahead of the long-axis scanner assembly. This means that long-axis beam shaping can already be performed in the long-axis far-field region. Furthermore, the long-axis beam-shaping optics and any additional short-axis beam-shaping optics can be combined into a common beam-shaping optics. This enables beam shaping in a preferred direction that differs from the long-axis and short-axis spatial directions.

[0040] In other cases, the long-axis scanner assembly can be arranged in the beam path of the short-axis relay optics. In other words, scanning in the long-axis spatial direction can be performed in the same region of the beam path to the relay in the short-axis spatial direction. In other words, scanning in the long-axis spatial direction and imaging or relaying in the short-axis spatial direction essentially occur in the same region of the beam path. This also applies to the long-axis focusing optics and / or the long-axis beam shaping optics.

[0041] The long-axis focusing optics and / or the short-axis focusing optics can also be configured for telecentric focusing of the beam path. Due to the telecentric concept, the angle of the output or exit beam does not change in the corresponding spatial direction across the working area. This also avoids or at least limits distortion.

[0042] Furthermore, the short-axis focusing optics may also be linear optics, and in particular, the length of the linear optics along the long axis is greater than the short-axis focusing focal length, at least by a factor of 2, preferably by a factor of 4 or 8, and / or the available long-axis working area is greater than the short-axis working area, at least by a factor of 2, preferably by a factor of 4 or 8. Compared to optics having a rotationally symmetric effect in the short-axis direction, a stronger focusing is possible due to the extended working field in the long-axis direction.

[0043] (Short axis) linear optics can also be designed as refractive optics, reflective optics, diffractive optics, geometric phase optics, or a combination of the aforementioned. Advantageously, refractive optics can be designed as on-axis systems, but typically require dispersion compensation and may be limited in performance as well as thermal and nonlinear propagation effects. Reflective optics can provide higher numerical apertures and better performance and are typically achromatic. The disadvantage is a higher sensitivity to matching and increased requirements for dimensional accuracy compared to refractive systems, which is usually accompanied by increased complexity due to off-axis designs.

[0044] Advantageously, focusing in the short-axis and / or long-axis spatial directions occurs, with the field curvature on the workpiece side largely negligible. These concepts, implemented specifically for the spatial directions, do not require z-tracking in the scan field caused by field curvature if the working area, in particular the working field, is flat and oriented vertically in the spatial direction. Field curvature can also be reduced by combining focusing in front of the long-axis scanner component with a component (field flattener) arranged after the long-axis scanner component, and dynamic z-tracking can be avoided. In contrast to telecentric concepts, f-theta concepts, due to the increasing placement angle towards the edge, enable an enlarged scan field compared to the free aperture of the optics with no field curvature.

[0045] In addition to or in conjunction with the previously described adaptation of the scanning speed or processing speed of the workpiece, the feed speed of the workpiece can also be changed. VR , to provide compensation for the relative movement between the workpiece and the optical device caused by the feed of the workpiece in the feed direction. Incidentally, this can be done at a substantially constant processing speed.

[0046] Scanning can also be used to vary the long axis scan speed. This is, for example, to enable machining during the possible acceleration time of a galvanometer scanner, or to enable machining despite position-dependent speed on the workpiece due to the constant angular velocity of a polygon scanner.

[0047] It is also possible to combine short-axis scanner components with long-axis scanner components to form effective energy density profiles and short-axis functions beyond simple compensation.

[0048] It is also possible to provide a (fast) switch in the laser processing system for turning the input beam on / off and / or switching the input beam to a different output beam.

[0049] Further details and advantageous configurations of the invention can be found in the following description, based on which exemplary embodiments of the invention are described and explained in more detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The first exemplary embodiment of the present invention is shown. Figure 5 A schematic overview of the optical apparatus of the laser processing system in FIG. 1 , the schematic overview being divided into the effects of the beam path along the short axis and the long axis of the generated linear output laser beam;

[0051] Figure 2 Shown for showing Figure 1 Schematic overview of the beam paths in the optical device in;

[0052] Figure 3 shows a schematic outline of an optical device according to a second exemplary embodiment of the present invention;

[0053] Figure 4 Shown is a diagram showing the Figure 1 Schematic overview of the long axis beam path in the optical device;

[0054] Figure 5 shows a schematic diagram of a laser processing system according to an exemplary embodiment of the present invention,

[0055] The laser processing system includes Figure 1 or Figure 3 One of the optical devices in;

[0056] Figure 6 and Figure 7 Shown for use Figure 5 A schematic overview of an exemplary embodiment of laser processing using a laser processing system;

[0057] Figures 8 to 12 Shows the use Figure 5 A schematic overview of an exemplary embodiment of a laser processing system for performing pulsed laser processing; and

[0058] Figures 13 to 24 Shows the use Figure 5A schematic overview of an exemplary embodiment of a laser processing system in which multi-point contour laser processing is performed. DETAILED DESCRIPTION

[0059] In the following description and in the drawings, the same reference symbols are used in each case for identical or corresponding features.

[0060] Figure 1 A laser processing system 100 (see Figure 5 ) is a first exemplary embodiment of an optical device 10 for converting an input laser beam 1 into an output laser beam 3, which extends along a longitudinal axis LA in a working area 40 or on a workpiece 42. The beam path 2 of the input laser beam 1 within the optical device 10 propagates in a propagation direction z (see Figure 2 The beam path in the telecentric case for the short axis KA, wherein the propagation direction z coincides with the optical axis of the optical device 10), and has an elliptical beam cross section in the working area 40 extending linearly along the long axis LA.

[0061] In addition to a linear extension along the long axis LA in the working area 40 , the generated outgoing laser beam 3 on the workpiece 42 also has an extension along a short axis KA, which extends orthogonally with respect to the long axis LA. For example, the aspect ratio of the short axis KA to the long axis LA may be 1:10.

[0062] For better understanding, Figure 1 The optical manipulation and effects of the beam path 2 between the input laser beam 1 and the output laser beam 3 are shown separately and in parallel for the short axis KA and the long axis LA. Furthermore, a far-field region and a near-field region can be distinguished within the beam path 2 in the propagation direction, relative to the working region 40. The respective far-field region is located close to the input laser beam 1, or at the short-axis input 20 for the short axis KA and the long-axis input 30 for the long axis LA—i.e., away from the working region 40 and the workpiece 42 positioned therein and to be processed by the output laser beam 3, and in particular within the optical device 10. The near-field region is located in the working region 40, where the workpiece 42 is located, and in particular coincides with it.

[0063] To generate the output laser beam 3, Figure 1The optical device 10 in the embodiment of the present invention has a short-axis scanner component 22 for scanning the beam path 2 along the short axis KA with a short-axis scanning direction component after the beam path 2 has entered through the input 20. The angular deflection short-axis scanner component 22 dynamically influences the short-axis position of the output laser beam 3 in the working area 40. In the present case, the beam path 2 or the output laser beam 3 in the working area 40 can be deflected in a corresponding short-axis far-field region and optionally additionally shaped by short-axis beam shaping optics by changing the angular distribution of the beam path 2 there, which in turn influences the spatial distribution of the output laser beam 3 in the working area 40. For example, additional short-axis beam shaping optics can be used for this purpose, such as a diffraction element which generates a short-axis multi-point profile, as described below with reference to Figures 13 to 24 4. As shown in more detail. Alternatively / additionally, the spatial distribution in the far field region and thus the angular distribution in the working area 40 can also be influenced, for example in the form of an interferometric modulation profile using multi-beam interference. With respect to the long axis LA, the long axis beam shaping optics 32 follow the beam path 2 for beam shaping or long axis shaping of the beam path 2 along the long axis LA, in particular including static, flexible and / or dynamic beam steering. For example, dynamic beam shaping can include a deflection superimposed on a deflection applied by the long axis scanner part 22. This can also be used to generate long axis multi-point profiles, in particular short axis and long axis multi-point profiles, as will be described later in Figures 13 to 24 As shown in more detail in .

[0064] With respect to the short axis KA, an optional short axis relay optics 24 in the beam path within the optical device 10 images the corresponding short axis far field region 2 in which the short axis scanner component 22 is arranged, which short axis relay optics follows the beam path 2 into the short axis far field region upstream of the short axis focusing optics 28. Short axis intermediate focusing is first performed by the relay lens 25 and then short axis realignment is performed by the relay lens 26. A short axis 4f relay optics is shown here, but it can also be designed as a short axis 2f relay optics with only one relay lens 26. This enables high resolution in the short axis direction by allowing the short axis relay optics 24 to control the short axis far field region between the relay lens 26 and the short axis focusing optics 28 and, in particular, to have a larger usable angular range. The relay optics 24 support such high-resolution control even with long-focus long-axis focusing and a large long-axis extension of the working area 40 and allow the long-axis scanner component 36 to be arranged between the short-axis scanner component 22 and the special short-focus short-axis focusing optics 28. In the same region of the beam path 2 for the long axis LA in the optical device 10, the long-axis focusing optics 34 for long-axis focusing and the scanner component 36 for scanning the beam path 2 along the long axis LA between the two relay lenses 25, 26 are present.

[0065] Finally, short-axis focusing optics 28 are arranged in the optical device 10 in the beam path 2 downstream of the previously mentioned optics for the short axis KA and focus the outgoing laser beam 3 along the short axis KA onto a working area 40 with a workpiece 42 .

[0066] Figure 2 Beam path 2 is shown expanded relative to the short axis KA and the long axis LA. The indicated scan of long-axis scanner component 36 can be performed up to a maximum angle βmax. Furthermore, telecentric post-scanner short-axis focusing is performed, i.e., short-axis focusing optics 28 are located downstream of long-axis scanner component 36 and short-axis scanner component 22 in beam path 2, with a focal length fKA. However, long-axis focusing is pre-scanner long-axis focusing, with long-axis focusing optics 34 located upstream of long-axis scanner component 36, with a focal length fLA. Long-axis field curvature can also be seen at a distance Lscan from long-axis scanner component 36 to working area 40.

[0067] Figure 3 The exemplary embodiment shows Figure 1A modification of the optical device 10 in FIG. 1 is provided, in which both short-axis and long-axis focusing are implemented according to a post-scanner concept, i.e., long-axis focusing optics 34 and short-axis focusing optics 28 are arranged in beam path 2, downstream of long-axis scanner component 36 and short-axis scanner component 22. This concept allows for an advantageous method with reduced field curvature in both directions, for example, by means of f-theta optics, and in particular also allows for a telecentric method with further reduced angular variation of the output beam in the processing region. For example, this concept also allows for combining short-axis realignment via relay lens 26 with long-axis focusing optics 34, thereby reducing the number of components with large required apertures.

[0068] Figure 4 Shown Figure 3 1 and 2. The associated beam path 2 for the long axis LA in the optical device 10 in FIG. Here, the telecentric long axis focus (fLA) downstream of the long axis scanner component 36 can be seen. This provides equal long axis angles of incidence on the workpiece 42 via the long axis working field and a vanishing long axis field curvature. The long axis scanner component 36 and the short axis scanner component 22 are implemented here as separate angularly deflecting reflective scanner components, for example as galvanometer scanner components, rotating polygon mirrors, or the like.

[0069] Short-axis scanning is performed in or near the short-axis far-field region by the short-axis scanner component 22 upstream of the long-axis scanner component 36. In the long-axis beam path 2, the optical components acting on the short axis KA and the short-axis far-field region are indicated by dashed lines (see Figure 2 ). Short-axis beam shaping or beam deflection is performed in an additional short-axis far-field plane upstream of the long-axis scanner component 36. Short-axis 4f relay image generation and re-collimation relay lens 26 are consistent with long-axis focusing optics 34. The short-axis focus is telecentric, with a short-axis focal length fKA that is short compared to the long-axis focal length fLA.

[0070] Figure 5 A laser processing system 100 is schematically shown for processing a workpiece 42 in a working area 40 by means of a linear output laser beam 3 of an optical device 10 in the laser processing system 100. The laser processing system 100 has a laser radiation source 50, in particular an ultrashort pulse laser radiation source, which provides an input laser beam 1 at the optical device 10, which is converted into an output laser beam 3 and is aligned with the workpiece 42 by means of the optical device 10.

[0071] Furthermore, the laser processing system 100 has a feed device 60, for example in the form of a conveyor belt, which feeds the workpiece 42, which can be, for example, in the form of a workpiece tape, in a feed direction VR relative to the optical device 10 and, therefore, relative to the output laser beam 3. In order to compensate for relative movements between the workpiece 42 and the optical device 10 caused by the feeding of the workpiece 42, the control device 70 of the laser processing system 100 is also configured to coordinate the scanning of the beam path with the short-axis scanning direction component relative to the feed using the short-axis scanner part 22.

[0072] A high degree of flexibility during feeding of the workpiece 42 and the quality of the laser processing are ensured by the fact that the long-axis scanner section 36 and the short-axis scanner section 22 are scanner sections that can work independently of each other but can be synchronized via the control device 70 .

[0073] Figure 6 and Figure 7 An exemplary embodiment of laser processing during feeding of a workpiece 42 is shown in FIG. Figure 6 The scanning direction (along the scanning portion S) is shown. SC ) on a single continuous line Processing or scanning time t s In the internal feed direction VR, the feed speed v R In the processing width B b Laser processing in the form of ablation is performed on the workpiece 42, where the laser processing is performed by means of a beam cross section or beam profile SP with a preferred processing direction of the long axis and a scanning area SB extending along the workpiece 42 at an angle α relative to the preferred processing direction VBR at a first angle α (0°<α<180°) relative to the advancement direction VR. This results in a workpiece-related processing length B l =B b / sin(α). To compensate for feed B s =v R ·t s , with an additional short axis scanning movement S of the short axis scanner part 22 of the scanning area KA =B s sin(α) matches the scanning direction and scanning speed v S For the entire processing width B b Or processing length B l On the processing, use the long axis to scan the area S LA =Bl+B s cos(α)=B b / sin(α)+B s ·cos(α).

[0074] As from Figure 6 and Figure 7As can be seen from the figure, for α>90°, a smaller long axis working area (AF) can cover the same processing width B. b For α>90°, use a lower scanning speed v LA The same effective scanning speed or processing speed v can be achieved p .

[0075] In order to limit the short axis scanning width and also the deviation of the continuous scanning processing line, the long axis scanning speed v LA Relative to feed speed v R Matched: v LA =v R ·[B b / (B s sin(α))+cos(α)]=B b / (t s ·sin(α))+v R ·cos(α).

[0076] Since the processing intensity depends on the scanning speed without further matching, the parameter v must be chosen appropriately. R 、B B 、B s and α, and other processing parameters (such as repetition rate, long axis profile extension, etc.) must be matched relative to these parameters.

[0077] For α≠90°, α>90° is preferred in order to reduce the required long axis scanning speed and the size of the working field (AB) compared to α<90°. A mirror image orientation of the machining geometry on the workpiece relative to the feed direction can be achieved by reversing the direction of the long axis scanning movement. S The selection of parameters that results in an effective scanning direction that is orthogonal to the feed direction VR (first angle α>90°, second angle β shown =90°) is advantageous for ensuring the z position, which can therefore only be guaranteed over an overall short range and in the feed direction VR. The latter is particularly advantageous when the workpiece is guided on deflection rollers in the processing area.

[0078] Figures 8 to 12 Shows the use Figure 5 Schematic overview of an exemplary embodiment of pulsed laser processing performed by the laser processing system 100 in FIG. 1 , where α>90°. Figure 8 shows the different speeds and directions used for processing, and Figures 9 to 12 Shown at t a At the beginning of processing or scanning, at t m In the middle of processing and at t e Laser processing at the end of the process, where Figure 12Shown at t m A variation where several lines are ablated at a distance significantly greater than the line width. In this example, the long axis scanning speed V LA Corresponding to the processing speed v p , feed speed v R Corresponding to the short axis scanning speed v KA , and processing width B b Corresponding to the long axis scanning length S LA By outputting the laser beam 3 at a scanning speed v S The scanning movement relative to the device in the scanning direction SR realizes that the output laser beam 3 moves in the long axis direction at a speed v LA The desired movement of the workpiece in the direction of the minor axis relative to the workpiece with a speed v R The arrangement moves.

[0079] Appropriate laser processing parameters (e.g. wavelength, energy density, pulse duration, etc.) are selected for ablation. The ablation depth is then controlled by the cumulative energy density at a certain location, e.g. the number of laser pulses acting at that location during one pass. In particular, the effective profile length, repetition frequency, and scanning speed v S If the effective scanning direction and feed direction are orthogonal, the following applies in each case for the scanning area and the working field: KA =B s and s LA =B b =B l At least a working field corresponding to the scanning field is required, plus an extension of the beam shape in some direction.

[0080] like Figure 12 As shown, the laser processing system 100 is also particularly suitable for use with a large minor axis extension p KA For example, ablation of several lines with a distance significantly greater than the line width is possible with a beam profile of a different size. Such applications require a large short axis working field extension a compared to the extension of a single unshaped partial beam profile. KA =p KA +s KA .

[0081] The following Figures 13 to 23The schematic diagrams in each of the figures show the multi-point distribution for non-astigmatic focusing on the left, with the profiles arranged on a line. To the right of the center of the figure, it is assumed that astigmatic focusing compresses the profile in the short axis direction, in this example by a factor of five. On the right, near the scanning direction SR, the line direction LR of the beam cross section or beam profile SP generated in the astigmatic system is symbolically indicated. To the left of the center, the energy density distribution for non-astigmatic focusing and for astigmatic focusing, integrated in the SR scanning direction and thus effective during the feed, is shown. By rotating the line direction LR, a coherent effective energy density distribution with spatially separated partial beam profiles can also be obtained.

[0082] like Figure 13 As shown, the astigmatic system not only leads to a compression of the partial profile, but also to a change in the line direction LR (if the line direction does not coincide with the direction of the short or long axis). In addition, the rotation leads to a beam profile SP that is extended in the direction of the long axis, without which the effective energy density integrated during the feed would be positively affected.

[0083] Figures 13 to 19 An example of is the case where there is no relative movement between the workpiece 42 and the optical device 10 (the scanning direction coincides with the preferred processing direction or effective scanning direction, as is common in the case of cutting, for example). During relative movement (see Figures 19 to 21 ), the effective scanning direction is usually selected to coincide with the long axis direction. In addition, it is then advantageous to select the preferred direction of the generated line of the laser beam to be parallel or perpendicular to the long axis direction so that no distortion or angle change occurs. Figure 13 In order to machine narrow lines with contouring during feed, the effective scanning direction can be selected to be either in the long axis direction or in the line direction. However, in the second case (a direction different from the long axis direction), it is not possible to achieve lines as narrow as if the machining line were oriented in the long axis direction. Using a telecentric-only design, rotation of the line direction during propagation and the resulting reduced z-position tolerance can be avoided.

[0084] Alternatively, if Figure 14 As shown, it is also possible to achieve an effective coherent intensity profile with separated partial profiles by aligning multiple beam profiles SP in the short axis direction and offsetting in the long axis and short axis directions without being affected by the astigmatism system in the line direction LR, and reducing the extension in the long axis direction and increasing the edge steepness.

[0085] like Figure 15 It is shown that the long axis extension can be further reduced by overlapping, preferably by avoiding intensity modulation coherence effects, and an intensity profile with increased edge steepness can be achieved that is actually, not just effectively, coherent.

[0086] like Figure 16 As shown, beam shaping can be performed simultaneously with directional components in both the short axis direction and the long axis direction and in a directionally flexible manner by preferably arranging it in overlapping (corresponding) short axis-long axis far field regions or short axis-long axis near field regions.

[0087] exist Figure 17 In the example in [1], two overlapping multi-point profiles are achieved in the processing zone using polarization separation. By varying the angle of the separation direction, the width of the effective beam profile SP acting during feed in the direction of the long axis is adjusted while maintaining edge steepness. Separation can be achieved using a beam-splitting component that produces an angular offset for the mutually perpendicular polarized partial beams and is preferably arranged in a rotational manner in the short-axis-long axis far-field region. Alternatively, a component that is arranged in a rotational manner in the overlapping short-axis-long axis near-field region can be used, which produces a spatial offset between the mutually perpendicular polarized partial beams.

[0088] Beam shaping of partial points of a multi-point profile in two spatial directions can also be achieved by arranging the shaping preferably in the long-axis-short-axis far-field region, here combined with intensity modulation-reduced polarization superposition (superposition of partial light points with time offset, separate wavelength ranges and / or mutually perpendicular polarization states).

[0089] exist Figures 16 to 18 In the example of , the multi-point profile has a preferred process direction corresponding to the direction of the short axis for the optical device 10 and is oriented towards the effective scanning direction. This preferred process direction remains substantially the same even in case of polarization separation rotation.

[0090] A preferred direction of machining on the workpiece 42 or a preferred machining direction is generally desired. Figures 19 to 24 By way of example, machining is shown in the form of a machining line which is as narrow as possible and which is continuous during the scanning using a multi-point profile.

[0091] Typically, the long axis direction is chosen to be along the processing line. The preferred processing direction of the multipoint line is affected by astigmatic focusing (or reduced ( Figures 14 to 18 ), or preferably increase ( Figures 19 to 22 )). The distance in the feed direction VR can be used to reduce damaging effects such as heat buildup and shielding. Scanning is preferably performed in the long axis direction without relative movement between the optical device and the workpiece away from the long axis direction (see Figure 19 and Figure 22 During relative movements with a directional component deviating from the long axis direction, the multipoint profile, the long axis direction and the processing line are preferably also oriented in parallel, and the relative movement is compensated by the matched scanning direction SR (see Figure 20 、 Figure 23 and Figure 24 ). Changes in relative movement speed, for example due to changes in feed speed v R and / or long axis scanning speed v LA The induced variations can be compensated for, for example, by scanning the angles while maintaining parallel orientation and scanning speed, ie by matching the short axis scanning speed.

[0092] On the other hand, if the scanning is limited to the long axis direction, it is necessary to compensate for the relative movement by means of a scanning direction SR different from the line and to orient the multipoint profile at a certain angle relative to the long axis direction, e.g. Figure 21 As shown in Figure 13 As can be seen, the overall result is an increase in the tolerances that must be adhered to and, in addition to increasing the processing width and reducing the edge steepness, a reduction in the flexibility to compensate for different feed speeds. Therefore, configuring the optical device 10 with beam shaping to form a preferred processing direction that is different from the major or minor axis direction (here, exemplified by a line with direction LR) represents a possible solution. However, the preferred processing direction is preferably the minor axis direction and / or the major axis direction.

[0093] Figure 23 and Figure 24 Full surface processing ( The machining geometry on the workpiece 42 has no preferred machining direction, so the long axis direction can be freely selected. Therefore, it is advisable to select this direction in the line direction so that the scanning direction SR in the optical device 19 is oriented orthogonally with respect to the feed direction VR. This allows machining in areas within the laser machining system 100 where the feed direction is minimized.

[0094] To improve the effectiveness of each scan with minimized long axis profile length and process-matched energy density or to achieve a suitable effective energy density distribution even with a small overlap of consecutive pulses and / or scans, customized beam profiles can also be advantageously used.

[0095] By way of example, a coherent multipoint line with reduced intensity modulation in the direction of the long axis is shown here (see Figure 15 and Figure 18 ).

[0096] Furthermore, with minimal pulse overlap, i.e., essentially during single-pulse processing, a flat-top beam profile can be used for full-surface processing with a tailored energy density distribution. In this case, the preferred processing direction is not directly but indirectly derived from the desired processing geometry: the scanning direction is selected perpendicular to the feed direction to minimize the system-dependent extension of the processing area. This results in a long-axis direction that is tailored to the beam shape, feed rate, and other parameters, and a coupled preferred processing direction.

Claims

1. A laser processing system (100) for processing a workpiece (42) by means of an output laser beam (3), wherein: The laser processing system (100) comprises: - a laser radiation source (50) for generating the input laser beam (1); an optical device (10) for converting the input laser beam (1) into an output laser beam (3) for machining the workpiece (42), the output laser beam propagating in a propagation direction (z) and having a beam cross section in a working area (40) extending along a long axis (LA) of the optical device (10), the optical device (10) comprising: long axis focusing optics (34) for focusing the beam path (2) within the optical device (10) between the input laser beam (1) and the output laser beam (3) along the long axis (LA), a long axis scanner component (36) for scanning the beam path (2) along the long axis (LA) at least with a long axis scanning direction component, short axis focusing optics (28) for focusing the beam path (2) along a short axis (KA), and a short axis scanner component (22) for scanning the beam path (2) along the short axis (KA) at least with a short axis scanning direction component; - a feeding device (60) for feeding the workpiece (42) relative to the optical device (10) in a feeding direction (VR); and - a control device (70) arranged to synchronize the scanning of the beam path (2) along the long axis scanning direction component with the scanning of the beam path (2) along the short axis scanning direction component.

2. The laser processing system (100) according to claim 1, wherein The synchronization performed by means of the control device (70) is arranged to compensate for relative movements between the workpiece (42) and the optical device (10) caused by feeding the workpiece (42) in the feed direction (VR) by scanning the beam path (2) with the short-axis scanner component (22).

3. The laser processing system (100) according to claim 1 or 2, wherein: The long-axis scanner component (36) and the short-axis scanner component (22) are scanner components capable of operating independently of each other.

4. The laser processing system (100) according to any one of the preceding claims, wherein: The long axis scanner component (36) is arranged to scan the beam path (2) in a preferred processing direction (VBR) parallel to the long axis (LA) such that a first angle α>0°, in particular α>90°, exists between the long axis scanning direction and the feed direction (VR).

5. The laser processing system (100) according to claim 4, wherein: At least for the average long axis scanning speed v LA =B b / (t s ·sin(α))+v R cos(α) sets the long axis scanner component (36), and / or at least for an average short axis scanning speed v KA =v r ·sin(α) sets the short axis scanner component (22), wherein B b is the processing width of the workpiece (42) perpendicular to the feed direction (VR), t s For processing length B l =B b / sin(α) processing time, and v R is the feed speed in the feed direction (VR).

6. The laser processing system (100) according to claim 5, wherein: For the long axis scanning field length s LA ≥B b / sin(α)+B s cos(α) sets the long axis scanner component (36), and / or for the short axis scan field width s KA ≥B s ·sin(α) sets the short axis scanner component (22), wherein B s is the length swept during the scan.

7. The laser processing system (100) according to any one of the preceding claims, wherein: The optical device (10) is designed such that the beam cross section is formed by a multi-point profile.

8. The laser processing system (100) according to claim 7, wherein: The multi-point profile has points distributed along the minor axis (KA) and the major axis (LA).

9. The laser processing system (100) according to claim 7 or 8, wherein: The multi-point profile having the line direction of the beam cross section resulting from astigmatic focusing of the optical device (10) is set to have an angle >0° relative to the long axis scanning direction component.

10. The laser processing system (100) according to any one of the preceding claims, wherein: The control device (70) is configured to match the laser power of the output laser beam (3) to the speed of the scanning of the beam path (2).

11. The laser processing system (100) according to any one of the preceding claims, wherein: The laser radiation source (50) is a pulsed laser radiation source (50), in particular an ultrashort pulsed laser radiation source.

12. The laser processing system (100) according to claim 11, wherein: The control device (70) is configured to match the pulse repetition frequency to the speed of the beam movement of the output laser beam (3) on the workpiece (42) and / or the speed of scanning performed by the long-axis scanner component (36).

13. The laser processing system (100) according to claim 11 or 12, wherein: The control device (70) is configured for position-synchronized pulse triggering along the long axis (LA).

14. The laser processing system (100) according to any one of claims 11 to 13, wherein: The control device (70) is configured to select laser processing parameters in a position-adapted manner along the longitudinal axis (LA).

15. The laser processing system (100) according to any one of the preceding claims, wherein: The long-axis scanner component carries the measurement beam path of the optical sensor system.

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