Laser machining system for machining a workpiece by means of an 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 arrangement (10), an advancement device (60) and a control device (70).

Description

[0001] Title: Laser processing system for processing a

[0002] workpiece using an output laser beam

[0003] Description

[0004] The invention relates to a laser processing system for processing a workpiece by means of an output laser beam, which comprises a feed device for feeding the workpiece relative to an optical arrangement of the laser processing system.

[0005] Such a laser processing system is known, for example, from DE3711905A1. In the laser processing system therein, an optical arrangement with a polygon wheel is used to laser process a material web that is moving relative to the optical arrangement.

[0006] With such laser processing systems from the state of the

[0007] Technology allows compensation of the relative movement of the material path relative to the optical arrangement by moving the polygon wheel accordingly.

[0008] The object of the invention is to provide an improved laser processing system for processing a workpiece that is moved relative to its optical arrangement, which is in particular more flexible and provides a higher processing quality than is the case in the prior art.

[0009] The object is achieved by a laser processing system according to claim 1. Accordingly, a laser processing system for processing a workpiece by means of an output laser beam is proposed, wherein the laser processing system has a laser beam source for generating an input laser beam. Furthermore, the laser processing system has an optical arrangement for converting the input laser beam into an output laser beam for processing the workpiece, which output laser beam propagates along a propagation direction and which, in a working region, has a beam cross-section extended along a long axis of the optical arrangement, wherein the optical arrangement has: an LA focusing optics for focusing a beam path within the optical arrangement between the input laser beam and the output laser beam along the long axis,an LA scanner component for scanning the beam path with at least one LA scanning direction component along the long axis, a KA focusing optic for focusing the beam path along a short axis of the optical arrangement running perpendicular to the long axis, optionally a KA beam shaping optic for beam shaping the beam path along the short axis, and a KA scanner component for scanning the beam path with at least one KA scanning direction component along the short axis. Furthermore, the laser processing system has a feed device for advancing the workpiece relative to the optical arrangement in a feed direction and a control device for synchronizing the scanning of the beam path along the LA scanning direction component with the scanning of the beam path along the KA scanning direction component.

[0010] In particular, the synchronization by means of the control device can be set up to compensate for a relative movement between the workpiece and the optical arrangement resulting from the feed of the workpiece in the feed direction by scanning the beam path with the KA scanner component.

[0011] According to the invention, a solution is thus provided in which separate scanner components are provided for the short axis and the long axis, which are, however, synchronized with each other in their scanning movement, in particular in such a way that the compensation of the relative movement between the workpiece and the optical arrangement can be carried out flexibly by means of corresponding control instructions from the control device to the KA scanner component, wherein the scanning with the LA scan direction component is not significantly influenced thereby. In particular, the compensation can be carried out solely by KA scanning with the KA scan direction component, so that KA scanning is also used solely for compensating the relative movement. In addition to the flexible

[0012] Reactivity of the inventive

[0013] According to the invention, a laser processing system can achieve a better representation of the beam cross-section or beam profile, which in turn improves the processing and thus improves the overall quality of the laser-processed workpiece.

[0014] Very particularly, a beam profile with a preferred direction can be used, which is in particular positioned exactly in relation to the workpiece and aligned with a preferred processing direction related to the workpiece. For processing continued on the workpiece along a line, in particular a preferred processing line, the optical arrangement and the LA scanning direction component are aligned, in particular in line with the long axis, preferably parallel to the preferred processing line of the workpiece. If there is a relative movement between the optical arrangement and the workpiece during laser processing which deviates from the LA direction, this can advantageously be compensated for by a particularly superimposed KA scanning movement in the KA scanning direction component, in particular in line with the short axis, wherein this KA scanning movement can preferably be adjusted independently of the LA scanning movement, as will be explained in more detail later.Preferably, the KA scanner component is positioned in a corresponding KA far-field region and separated from the LA scanner component in the beam propagation direction.

[0015] The short axis and the long axis of the optical arrangement and thus of its optics are in particular perpendicular to one another. In the proposed astigmatic optical arrangement the beam cross section can change both in terms of size and shape during propagation. In the working region on the workpiece the output laser beam can have an elliptical beam profile, in particular with an aspect ratio of short axis to long axis of for example at least 1:3, in particular at least 1:5 and furthermore in particular 1:10, so that reference is made here to a line-like beam cross section extended along the long axis LA. In particular line optics extended in the LA spatial direction can be used for focusing in the KA spatial direction.

[0016] Components such as optics, (spatial) directions, regions or other information are supplemented herein by "KA-" for short axis or "LA~" for long axis in order to indicate their correlation with the respective axis, for example the optical effect of an optic on the short axis or long axis, and thus to differentiate between the short axis and the long axis. The components are preferably aligned with their preferred directions in the respective KA or LA spatial direction. The beam cross-section, also referred to as the beam profile, is typically extended in the LA spatial direction, particularly along its greatest extent, and very particularly in a linear manner at least in the broadest sense. Depending on the configuration, other extensions are also conceivable in which the beam cross-section is extended lengthwise in a direction deviating from the LA spatial direction.The beam path refers to the laser beam within the optical arrangement, i.e., between the entrance of the optical arrangement, where it is referred to as the input laser beam, and the exit of the optical arrangement, where it is referred to as the output laser beam. A far-field region of the beam path can be located within the optical arrangement, while a near-field region of the beam path or the output laser beam, in contrast, is linked to the working region, and is located in particular in or on the workpiece in the working region.

[0017] The LA focusing optics and / or the KA focusing optics are preferably designed as an astigmatic / anamorphic optical component or group of components, possibly as a cylindrical optic, i.e., their optical functionality is limited to the LA spatial direction or the KA spatial direction, respectively. The LA and KA scanner components can, for example, each be a mirror scanner with a galvanometer drive and / or a rotating polygon mirror scanner.

[0018] The feed device can, for example, be a conveyor belt or a rotating deflection roller, on which a particularly continuous workpiece or a workpiece path is provided in front of the optical arrangement. A workpiece path as a workpiece can be processed accordingly, for example, divided, by the output laser beam.

[0019] The control device can be a cross-component control device of the laser processing system or can be provided in one or more components of the laser processing system, for example part of the optical arrangement, in particular the KA scanner component.

[0020] Although reference is made here to one input laser beam and one output laser beam, it is conceivable and possible for the optical arrangement to generate a plurality of output laser beams or partial beams (from one or more input laser beams), in particular in the KA spatial direction in the working region, which are parallel or moved in parallel. The output laser beams or partial beams can be offset in the working region with regard to location and / or angle. This can be achieved by partial beam profiles that are separated in the KA spatial direction in the working region or by means of multiple beam interference of overlapping partial beam profiles with KA angular offset in the working region. The use of partial beams allows the width of the output laser beam to be increased or parallel line processing to be carried out when offset in the KA spatial direction. For example, such parallel line processing can be used for dicing electronic chips (so-called"Dicing"), multi-line engraving of electrical sheets, descaling of metal surfaces or structuring of battery foils.

[0021] In particular, the LA scanner component and the KA scanner component can be independently functional scanner components. This functional independence of the scanner components from each other, which can be separate components or not functionally dependent on each other, provides maximum flexibility for positioning the output beam in the processing region and, in particular, for compensating for the relative movement between the workpiece and the optical assembly resulting from the workpiece feed.

[0022] Furthermore, in particular, the LA scanner component can be configured to scan the beam path or output laser beam along a preferred processing direction parallel to the long axis, in particular a preferred line direction, such that a first angle a > 0 ° exists between an LA scanning direction or preferred processing direction and the feed direction. The first angle a can in particular be 0 ° < a < 180 °, for example a = 90 °. The preferred processing direction of the beam profile can in particular be oriented in the LA direction and / or the KA direction.

[0023] In particular, the first angle a can be > 90°. In the case of such a deviation of the preferred machining direction from being orthogonal to the feed direction, an LA scanning direction with partial compensation of the relative movement is set in order to reduce the required scanning field, the required scanning speed, etc.

[0024] In addition, the LA scanner component can be configured for at least an average LA scanning speed v LA = B b / ( t s • sin (α) ) + v R • cos (a) and / or the KA scanner component at least for an average KA scanning speed (in the coordinate system of the arrangement) VRA = v r • sin (a) be set up, where B b a machining width on the workpiece perpendicular to the feed direction, t s a processing time for the processing length B b = B b / sin (a) (from machining start to machining end of the machining length during a scanning process) and v Ris the feed rate in the feed direction. The effective scanning speed is related to the relative movement between the laser beam and the workpiece, so that it can also be referred to as a processing speed. With such a design, it is possible to achieve rectilinear processing on the workpiece, in particular a minimum line width and / or edge steepness of the effective beam cross-section (while maintaining the other parameters). The effective LA scanning speed is essentially relevant for the processing effect, while the KA scanning speed serves solely to compensate for the relative movement. The quotient of processing width and processing time B b / t s can be defined as (average) processing speed v B = B b / t s = B b ■ sin (a) / t sperpendicular to the feed direction. The feed B s of the workpiece over the machining time t s represents the minimum period of the machining operations in the feed direction (assuming that no multiple partial beams are being used simultaneously and that the system dead time is 0%, i.e. the start of the next machining operation occurs instantaneously after the end of the previous machining operation).

[0025] In this case, it can be provided that the LA scanner component for an LA scan field length S L A > B b / sin (a) + B s • cos (a) and / or the KA scanner component for a KA scan field width SKA h B s • sin (oc) is set up, where B s a length swept during the scan and in particular during the processing time t s and where B sparticularly oriented in the feed direction. In this case, processing can be performed with the optical arrangement perpendicular to the feed direction without any offset. Otherwise, the specifications regarding the scanning range refer particularly to the center of the beam profile.

[0026] Furthermore, the optical arrangement can be designed such that the beam cross-section is formed by a multi-spot profile. Due to the astigmatic focusing of the optical arrangement, such a multi-spot profile is stretched along a resulting line direction, thus generating the beam cross-section on the workpiece.

[0027] The multi-spot profile can be configured to have spots distributed along both the short and long axes. Alternatively, it is also possible to align the spots of the multi-spot profile only along the short axis or along the long axis. The spots can also be arranged in an overlapping pattern, as explained in more detail later.

[0028] In particular, it can be provided that the multi-spot profile, with a line direction of the beam cross-section resulting from astigmatic focusing of the optical arrangement, is set at an angle of incidence > 0 ° with respect to the LA scan direction component, which angle coincides in particular with the long axis. Such a selection enables simplified assurance of the z-position tolerance by limiting machining to a short area in the feed direction. In this way, for example, in a roll-to-roll application, machining can also take place in an area in which the workpiece rests on a deflection roller.

[0029] Furthermore, the control device can be configured to adapt the laser power of the output laser beam to the speed of the beam movement of the output laser beam on the workpiece and / or the scanning of the beam path. By adapting the laser power to the workpiece-specific, effective scanning speed, a typically fluctuating, but now reproducible, machining result can be achieved. The advantage of this is accordingly improved reproducibility with increased flexibility and tolerance.

[0030] In addition, it can be provided that the laser beam source is a pulsed, in particular ultrashort pulsed, laser beam source. A pulsed laser beam source allows extended control of the laser processing, in particular with regard to the heat accumulation generated. Relevant in this case are the typically achievable spatial and temporal gradients of the effect in the workpiece. A threshold intensity or threshold fluence is often required, and the intensity and fluence must be selected within suitable windows. With a CW laser beam source, such thresholds or ranges can often only be achieved with difficulty, as the power, beam shape, and beam dynamics must be selected accordingly. However, the pulsed laser beam source has proven to be advantageous in the present application and is preferred over a CW laser beam source. This makes it possible to provide processing that can be modulated with precise position in the respective scanning direction.An ultrashort pulsed laser beam source is particularly advantageous when an intensity threshold is present or when working via a dynamic thermomechanically induced mechanism. Even with high beam dynamics, precise positioning is possible, and the beam movement on the workpiece is negligible over the pulse duration.

[0031] In this case, the control device can be configured to adapt a pulse repetition frequency to the effective scanning speed of the laser scanner component. This allows the respective laser pulse parameters, the energy per unit length, and the overlap or modification distance to be maintained on the workpiece. Adaptation to a speed that varies across the scanning range, resulting in a deflection-dependent speed on the workpiece, is also possible.

[0032] Furthermore, the control device can be configured for position-synchronized pulse triggering along the long axis. This means that the laser pulses are triggered based on specific positions on the long axis, i.e., synchronized with these. This allows for greater precision compared to adjusting the repetition frequency, since the position can also be controlled. Furthermore, position-synchronized pulse triggering is suitable for increased dynamics, e.g., for machining under acceleration using a galvo scanner as the LA scanner component.

[0033] Furthermore, it can be provided that the control device is set up for position-adapted selection of laser processing parameters along the long axis. This means that the laser processing parameters are selected as a function of the position on the long axis. This allows in particular an adaptation of the laser processing parameters to deflection-dependent beam properties, such as distortion, by e.g. adjusting the pulse energy and repetition frequency. This also allows an adaptation to workpiece properties or processing specifications that vary in the scanning direction. For example, in dicing, other laser processing parameters can be used in edge coatings or at intersection points of ablation lines aligned perpendicular to one another.

[0034] Furthermore, it can be provided that the LA scanner component carries a measuring beam path of an optical sensor. The LA scanner component can therefore also be used for diagnosis at the same time, in particular it can precede, accompany and / or follow the processing. Advantageously, a correlation to the beam path for processing can be used. Possible options include, for example, precedent position detection, distance and / or depth detection (preceding and / or following), in particular for adapting the laser processing parameters in the current or subsequent pass, process observation, e.g. emission, reflection, OCT, WIM, . . . , in particular during a follow-up pass, and / or e.g. the detection of the respective process phase, for example by means of spectroscopy, e.g. the achievement of a back-side coating.

[0035] Furthermore, it is possible for the optical arrangement to further comprise KA relay optics for imaging a KA far-field region of the beam path within the optical arrangement along the short axis. Such an optical arrangement therefore permits an astigmatic optical concept with particularly strong focusing in the particularly high-resolution short axis (KA) or the KA spatial direction and a large working field in the long axis (LA) or the LA spatial direction. This permits improved control of the beam distribution in an enlarged working field in the KA spatial direction by, in particular, the KA relay optics and / or optionally the KA relay optics between the scanner component scanning at least in the LA spatial direction as a scanning direction component and the KA focusing optics.one or more further KA optics are integrated with additional optical functionality that supports influencing the angular and / or spatial distribution in a KA far-field region corresponding to the working region of the output laser beam.

[0036] The relay optics ensure in particular a KA-

[0037] Far-field imaging between the KA scanner component, which in particular images a KA far-field region assigned to the working region via the KA focusing and localized after the (LA) scanner component backwards in the beam propagation direction into a region closer to the beam entrance into a corresponding KA far-field region. This corresponding KA far-field region is preferably located in front of the LA focusing and / or the LA scanner component. The KA beam distribution in the area of ​​the corresponding KA far-field region is influenced in particular by means of the KA beam former optics. The KA scanner component is arranged in particular in the area of ​​a corresponding KA far-field region and preferably essentially influences the KA angular distribution in this region. A component of the KA far-field imaging or KA relay optics are preferably arranged between KA focusing and LA focusing and / or the LA scanner component.The KA far-field imaging preferably includes a further component, which is preferably arranged in front of the LA scanner component. The KA relay optics preferably comprises a 4 f-.

[0038] Telescope with cylindrical optics. The KA relay optics can, for example, be implemented in a known manner using two correspondingly aligned aspherical lenses or optics, which are also referred to herein as relay lenses. In particular, it can be a KA-4 f relay optic.

[0039] In particular, it is possible for the KA relay optics to be positioned behind the KA beamformer optics in the beam path. The KA relay optics thus allows the KA far field to be controlled after beam formation by the KA beamformer optics.

[0040] It is also possible for the KA focusing optics to be positioned behind the KA relay optics in the beam path. This allows the KA focusing optics to focus the output laser beam directly onto the workpiece in the working region from the KA far-field region of the KA relay optics.

[0041] Furthermore, it is possible and preferred that the KA focusing optics are arranged in the beam path behind the LA scanner component. In this way, the KA focusing optics can focus the output laser beam directly onto the workpiece in the working field. In particular, the distance of the KA focusing optics from the working region is thus smaller than the distance of the LA scanner component from the working region; for example, the distance of the KA focusing optics from the working region can be half or less of the distance of the LA scanner component from the working region. The extent of the aperture of the KA focusing optics preferably corresponds to at least half the LA working field length in the working region.

[0042] It is also possible and preferred for the KA scanner component to be positioned in front of the LA scanner component in the beam path. This allows LA beam shaping to occur in or before the corresponding KA far-field region.

[0043] Furthermore, it is possible for the LA focusing optics to be arranged behind the LA scanner component in the beam path. Alternatively, it is possible for the LA focusing optics to be arranged in front of the LA scanner component in the beam path.

[0044] In other words, the LA scanner component can advantageously be used as a post (objective) scanner component with respect to the LA spatial direction, even if the LA scanner component is arranged in front of the KA focusing optics.

[0045] It is also possible for the optical arrangement to further comprise an LA beam former optic for shaping the beam path along the long axis. The LA beam former optic, like a possible additional KA beam former optic, can include or provide, for example, multiplexing, mapping, a superimposed scanning movement and / or further KA beam former functionalities or LA beam former functionalities. Furthermore, several input beams can also be provided. In this case, the LA beam former optic could align the resulting partial beams with respect to one another.

[0046] The LA beamforming optics can be positioned in the beam path upstream of the LA scanner component. This allows LA beamforming to occur in an LA far-field region. Furthermore, the LA beamforming optics and any additional KA beamforming optics can be combined as a single beamforming optic. This allows beamforming with a preferred direction that differs from the LA spatial direction and the KA spatial direction.

[0047] Otherwise, it is possible for the LA scanner component to be arranged in the beam path of the KA relay optics. In other words, scanning in the LA spatial direction can occur in the same area of ​​the beam path as the relay in the KA spatial direction. In other words, scanning in the LA spatial direction and imaging or the relay in the KA spatial direction occur essentially in the same area of ​​the beam path. The same can apply to the LA focusing optics and / or the LA beamforming optics.

[0048] It is also possible for the LA focusing optics and / or the KA focusing optics to be configured for telecentric focusing of the beam path. With a telecentric concept, the angle of incidence of the output beam(s) does not change in the corresponding spatial direction across the working field of the working region. This simultaneously avoids or at least limits distortion.

[0049] Furthermore, it can be provided that the KA focusing optics is a line optic, wherein in particular a length of the line optics along the long axis exceeds a focal length of the KA focusing by at least a factor of 2, preferably of 4 or 8, and / or the usable LA working field exceeds the KA working field by at least a factor of 2, preferably of 4 or 8. In this way, strong focusing with an extended working field in the LA direction is possible compared to optics with a rotationally symmetric effect in the KA direction. It can also be provided that the (KA) line optics is designed as a refractive optic, reflective optic, diffractive optic, geometric phase optic or as a combination of the above. Refractive optics can advantageously be designed as on-axis systems, but often require dispersion compensation and can be more complex with regard to...Performance limitations, thermal and nonlinear propagation influences, can have a limiting effect. Reflective optics can offer a higher numerical aperture and better performance and are typically achromatic. Disadvantages compared to refractive systems are their higher alignment sensitivity and increased demands on shape fidelity, often coupled with increased complexity due to an off-axis design.

[0050] Focusing is advantageously carried out in the KA and / or LA spatial direction with largely negligible field curvature on the workpiece side. These concepts, which can be implemented separately for each spatial direction, do not require any z-tracking caused by field curvature in the scan field if the work region, in particular a work field, is flat and vertically aligned in the respective spatial direction. The field curvature can also be reduced and dynamic z-tracking avoided by combining focusing in front of the LA scanner component with a component arranged after the LA scanner component (field flattener). In contrast to a telecentric concept, an f-theta concept allows a scan field that is larger than the free opening of the optics thanks to a parking angle that increases towards the edge and has a vanishing field curvature. In addition to or alongside the previously described adjustment of the scanning speed orMachining speed on the workpiece can also be provided that the feed rate v. R of the workpiece is varied to compensate for the relative movement between the workpiece and the optical assembly resulting from the feed of the workpiece in the feed direction. This can, moreover, be done at a substantially constant machining speed.

[0051] A scan can also be used to vary the LA scanning speed. For example, to enable machining during the acceleration times of a possible galvo scanner or to enable machining on the workpiece despite the position-dependent speed resulting from the constant angular velocity of a polygon scanner.

[0052] A combination of KA and LA scanner components to form the effective fluence profiles and KA functionality beyond pure compensation are also possible.

[0053] It is also possible to provide a (fast) switch in the laser processing system for switching the input beams on / off and / or switching over to different output beams.

[0054] Further details and advantageous configurations of the

[0055] The invention can be found in the following description, which describes and explains exemplary embodiments of the invention in more detail. They show:

[0056] Figure 1 is a schematic sketch of an optical

[0057] Arrangement for the laser processing system of Fig. 5 according to a first embodiment of the invention divided into the influencing of the beam path along a short axis and a long axis of a generated line-like output laser beam;

[0058] Figure 2 is a schematic sketch to explain the

[0059] Beam path in the optical arrangement of Fig. 1;

[0060] Figure 3 is a schematic sketch of an optical

[0061] Arrangement according to a second embodiment of the invention;

[0062] Figure 4 is a schematic sketch to explain the

[0063] Ray path along the long axis in the optical arrangement of Fig. 1;

[0064] Figure 5 is a schematic view of a

[0065] Laser processing system according to an embodiment of the invention, comprising one of the optical arrangements of Fig. 1 or

[0066] 3;

[0067] Figures 6, 7 are schematic sketches of embodiments of laser processing with the laser processing system of Fig. 5;

[0068] Figures 8-12 schematic sketches of a

[0069] Example of a pulsed

[0070] Laser processing with the

[0071] Laser processing system of Fig. 5; and

[0072] Figures 13-24 schematic sketches of a

[0073] Example of a multi-spot profile laser processing with the

[0074] Laser processing system of Fig. 5.

[0075] In the following description and in the figures, the same reference symbols are used for identical or corresponding features.

[0076] Figure 1 shows a first embodiment of an optical arrangement 10 for a laser processing system 100 (see Fig. 5) for converting an input laser beam 1 into an output laser beam 3 extending in a working region 40 or on a workpiece 42 along a long axis LA. The beam path 2 of the input laser beam 1 within the optical arrangement 10 propagates along a propagation direction z (see beam path in Fig. 2 for a telecentric case with respect to the short axis KA, in which the propagation direction z coincides with the optical axis of the optical arrangement 10) and has an elliptical beam cross-section in the working region 40 which extends linearly along the long axis LA.

[0077] In addition to the linear extension along the long axis LA in the working region 40, the generated output laser beam 3 on the workpiece 42 also has an extension along a short axis KA running orthogonally to the long axis LA. An aspect ratio of the short axis KA to the long axis LA can be, for example, 1:10.

[0078] For the sake of better understanding, Fig. 1 shows the optical manipulation of the beam path 2 between the input laser beam 1 and the output laser beam 3 with effect for the short axis KA and the long axis LA separately and in parallel. Furthermore, within the beam path 2 in the propagation direction, a distinction can be made between far-field regions related to the working region 40 and near-field regions. A corresponding far-field region is located close to the input laser beam 1 or at the KA input 20 for the short axis KA and the LA input 30 for the long axis LA, i.e. away from the working region 40 and the workpiece 42 positioned there, which is to be processed by the output laser beam 3, and in particular within the optical arrangement 10. The near-field region is located in the working region 40 in which the workpiece 42 is located, and in particular coincides with this.

[0079] 1 has a KA scanner component 22 for scanning the beam path 2 after entry through the entrance 20 with a KA scanning direction component along the short axis KA. The angle-deflecting KA scanner component 22 dynamically influences the KA position of the output laser beam 3 in the working region 40. In this case, the beam path 2 or output laser beam 3 in the working region 40 can be deflected in the corresponding KA far-field region and optionally additionally shaped by KA beam former optics by changing the angular distribution of the beam path 2 there, which then affects the spatial distribution of the output laser beam 3 in the working region 40. For example, additional KA beam former optics can be used for this purpose, e.g. a diffractive element that generates a KA multispot profile, as will be explained in more detail later in Fig.13 to 24. It is also possible to alternatively / supplementarily influence the spatial distribution in the far-field region and thus to influence the angular distribution in the working region 40, e.g. in the form of an interference-modulated profile by means of multi-beam interference. With regard to the long axis LA, an LA beam former optic 32 follows in the beam path 2 for beam shaping or LA shaping of the beam path 2 along the long axis LA, in particular including static, flexible and / or dynamic beam guidance. Dynamic beam shaping can, for example, comprise a deflection superimposed on the deflection imposed by the LA scanner component 22. This can also generate an LA multi-spot profile, in particular a KA and LA multi-spot profile, as will be shown in more detail later with reference to Figs. 13 to 24.

[0080] With regard to the short axis KA, an optional KA relay optic 24 follows in the beam path 2, which in the beam path 2 within the optical arrangement 10 the corresponding KA-

[0081] Far-field region, in which the KA scanner component 22 is arranged, is imaged into the KA far-field region in front of the KA focusing optics 28. Relay lens 25 initially performs KA intermediate focusing and then relay lens 26 performs KA re-collimation. In the present case, a KA-4 f relay optics is shown, but it can also be designed as a KA-2 f relay optics with only one relay lens 26. This enables high resolution in the KA direction, as the KA relay optics 24 allows control of the KA far-field region between the relay lens 26 and the KA focusing optics 28, with a larger usable angular range. The relay optics 24 supports this high-resolution control even with long focal length LA focusing and large LA extension of the working region 40, and allows the LA scanner component 36 to be arranged between the KA scanner component 22 and the particularly short focal length KA focusing optics 28.In the same area of ​​the beam path 2, with respect to the long axis LA in the optical arrangement 10, there are an LA focusing optics 34 for LA focusing and a scanner component 36 for scanning the beam path 2 along the long axis LA between the two relay lenses 25, 26.

[0082] Finally, in the beam path 2 behind the aforementioned optics, a KA focusing optic 28 with respect to the short axis KA is provided in the optical arrangement 10, which focuses the output laser beam 3 along the short axis KA onto the working region 40 with the workpiece 42.

[0083] Fig. 2 shows the beam path 2 unfolded with respect to the short axis KA and the long axis LA. The indicated scanning of the LA scanner component 36 can be carried out up to an angle ßmax. Furthermore, a telecentric post-scanner KA focusing takes place here, i.e. KA focusing optics 28 in the beam path 2 behind the LA scanner component 36 and the KA scanner component 22, with a focal length fKA. The LA focusing is in turn a pre-scanner LA focusing with the LA focusing optics 34 in front of the LA scanner component 36 with the focal length fLA. Also visible is the LA-

[0084] Image field curvature at the distance Lscan from LA scanner component 36 to the working region 40 .

[0085] The embodiment of Fig. 3 shows a modification of the optical arrangement 10 of Fig. 1, in which both KA and LA focusing are designed according to the post-scanner concept, i.e. the LA focusing optics 34 and the KA focusing optics 28 are arranged in the beam path 2 behind the LA scanner component 36 and the KA scanner component 22. This concept allows advantageous approaches in both directions with reduced field curvature, such as by means of f-theta optics, and in particular also a telecentric approach with further reduced variation of the angle of the output beams in the processing region. With such a concept, for example, the KA re-collimation by relay lens 26 and the LA focusing optics 34 can be combined, thus reducing the number of components with a large required aperture.

[0086] Fig. 4 shows an associated beam path 2 of the optical arrangement 10 of Fig. 3 with respect to the long axis LA. Visible here is the telecentric LA focusing (fLA) downstream of the LA scanner component 36. This provides vanishing LA field curvature and a uniform LA angle of incidence on the workpiece 42 across the LA working field. The LA scanner component 36 and the KA scanner component 22 are designed here as individual angle-deflecting, reflective scanner components, e.g., as galvo scanner components, rotating polygon mirrors, etc.

[0087] The KA scanning upstream of the LA scanner component 36 by the KA scanner component 22 takes place in or near the KA far-field region. The optical components acting on the short axis KA as well as the KA far-field regions are symbolized in the LA beam path 2 by means of broken lines (cf. Fig. 2). The KA beam shaping or beam deflection takes place in a further KA far-field plane upstream of the LA scanner component 36. A KA-4 f-relay image is generated, with the re-collimating relay lens 26 coinciding with the LA focusing optics 34. The KA focusing takes place telecentrically with a short focal length of the short axis fKA compared to the focal length of the long axis fLA.

[0088] Figure 5 schematically shows a laser processing system 100 for processing the workpiece 42 on the working region 40 by means of the linear output laser beam 3 of the optical arrangement 10 in the laser processing system 100. The laser processing system 100 has a laser beam source 50, in particular an ultrashort pulse laser beam source, which provides the input laser beam 1 to the optical arrangement 10, which is converted into the output laser beam 3 and is aligned with the workpiece 42 by means of the optical arrangement 10.

[0089] Furthermore, the laser processing system 100 has a feed device 60, for example in the form of a conveyor belt, which advances the workpiece 42, which can be present, for example, as a workpiece belt, in a feed direction VR relative to the optical arrangement 10 and thus to the output laser beam 3. In order to compensate for a relative movement between the workpiece 42 and the optical arrangement 10 resulting from the feed of the workpiece 42, a control device 70 of the laser processing system 100 is also configured to coordinate the scanning of the beam path with the KA scanner component 22 in the KA scanning direction component relative to the feed.

[0090] Because the LA scanner component 36 and the KA scanner component 22 are independently functional scanner components, but can be synchronized via the control device 70, a high degree of flexibility and quality of the laser processing of the workpiece is achieved.

[0091] 42 achieved under the feed .

[0092] Examples of laser processing with feed of the workpiece 42 are shown in Fig. 6 and 7. In Fig. 6, laser processing in the form of removal over a processing width Bb at a feed rate v R in the feed direction VR within a processing or scanning time t s in a single pass on a continuous line in a (arrangement-related) scanning direction (along the scanning path S S c) , which here runs at an angle a to the preferred machining direction VBR along the workpiece 42 , with a first angle a ( 0 ° < a < 180 ° ) to the feed direction VR by means of a beam cross-section or beam profile SP with LA preferred machining direction and scan area SB . This results in a workpiece-related machining length Bi = Bb / sin (a) . To compensate for the feed B s = v R• t s is achieved by an additional KA scanning movement of the KA scanner component 22 with a scanning range SKA = B s • sin (a) the scanning direction and scanning speed v s adapted. For machining over the full machining width Bb or machining length Bi, an LA scanning area S LA = Bl + B s • cos (a) = B b / sin (a) + B s • cos (a) is used.

[0093] As can be seen from Fig. 6 and 7, for a > 90 ° with a smaller LA working field (AF) the same machining width Bb can be covered. For a > 90 ° the same effective scanning speed or process speed v p with lower scanning speed v LA To limit the KA scan width and also the offset of consecutively scanned processing lines, the LA scan speed v LA relative to the feed rate v Radapted: v LA = v R • [B b / (B s • sin(a) ) + cos (a) ] = B b / (t s -sin(oc) ) + v R -cos(a) .

[0094] Since the processing strength depends on the scanning speed without further adjustments, the parameters v R , B b , B s and a to choose appropriately and other process parameters (e.g.

[0095] Repetition frequency, LA profile extension, etc.) to adapt to it.

[0096] For a V 90°, a > 90° is preferably selected to reduce the required LA scanning speed and working field (AB) size compared to a < 90°. A mirrored alignment of the machining geometry on the workpiece relative to the feed direction can be achieved by reversing the direction of the LA scanning movement. To ensure the z-position, it is advantageous to select parameters that allow an effective scanning direction with scanning speed v sorthogonal to the feed direction VR (first angle α > 90°, shown second angle β = 90°), so that the z-position only needs to be ensured in a short range overall in the feed direction VR. The latter is particularly advantageous if the workpiece is guided on a deflection roller in the machining region.

[0097] Figures 8 to 12 show schematic sketches of an embodiment of a pulsed laser processing with the

[0098] Laser processing system 100 of Fig. 5 at a > 90°. Fig. 8 shows the different speeds with their directions for processing, and Figs. 9 to 12 show the respective laser processing at the start of processing or scanning at t a , to the middle of the processing at t m and at the end of processing at t e , where Fig. 12 shows a variant with removal of several lines at t mwhose distance significantly exceeds the line width. In this case, the LA scanning speed V LA the process speed v p corresponds to the feed rate v R the KA scanning speed VKA and the processing width B b the LA scan length S LA The desired movement of the output laser beam 3 in the LA direction with the velocity v LA on which relative to arrangement with the speed v R The workpiece moving in the KA direction is arranged in the scanning direction SR with the scanning speed v by means of a scanning movement of the output laser beam 3 s achieved .

[0099] Suitable laser processing parameters (such as wavelength, fluence, pulse duration, etc.) are selected for ablation. The ablation depth is then controlled via the accumulated energy density at the location, e.g., the number of laser pulses acting at the location during one pass. For this purpose, the effective profile length, repetition frequency, and scanning speed v are particularly important. s adjusted accordingly. If the effective scanning direction and the feed direction are orthogonal, the scan area and the working field are each SKA = B s and s LA = B b= Bi. A working field corresponding to the scan field plus the beam shape extension in the respective direction is required as a minimum. As Fig. 12 shows, the laser processing system 100 is particularly suitable in conjunction with beam profiles of large KA extension PKA, e.g., for ablating multiple lines whose spacing significantly exceeds the line width. Such an application requires a large KA working field extension aKA = PKA + SKA - compared to the extension of a single unshaped partial beam profile.

[0100] In the schematic representations of the following Figs. 13 to 23, a multi-spot distribution with non-astigmatic focusing is shown on the left, with the profiles arranged in a line. In the representation to the right of the center, it is assumed that the astigmatic focusing compresses the profile in the KA direction, here by way of example to one fifth. On the right, next to the scanning direction SR, the resulting line direction LR of the beam cross-section or beam profile SP in the astigmatic system is symbolized. To the left of the center, fluence profiles integrated in the scanning direction SR and thus effective during feed are illustrated with and without astigmatic focusing. A coherent effective fluence profile can be achieved by rotating the line direction LR, even with spatially separated partial beam profiles.

[0101] As Fig. 13 shows, in addition to compressing the partial profiles, the astigmatic system also changes the line direction LR if this does not correspond to the KA or LA direction. In addition, the rotation results in a beam profile SP that is extended in the LA direction, without this having a positive effect on the effective fluence integrated under feed. The examples in Figs. 13 to 19 are without relative movement between the workpiece 42 and the optical arrangement 10 (the scanning direction corresponds to the preferred machining direction or effective scanning direction, as is typical for dicing, for example). Under relative movement (cf. Figs. 19 - 21), the effective scanning direction is typically selected to correspond to the LA direction. Furthermore, it is then advantageous to select the preferred direction of the generated line of the laser beam parallel or perpendicular to the LA direction so that no distortion or change in angle occurs.To machine a narrow line with a profile like the one shown in Fig. 13 while feeding, the effective scanning direction can be selected in the LA or LR direction. However, even in the latter case, a line as narrow as that achieved with an alignment of the machining line in the LA direction (in a direction deviating from the LA direction) cannot be achieved. By using only telecentric design, rotation of the line direction under propagation and thus a reduced z-position tolerance can be avoided.

[0102] Alternatively, as shown in Fig. 14, effectively connected intensity profiles with separated partial profiles can also be achieved by several beam profiles SP aligned in the KA direction and offset in the LA and KA directions without the influence of the astigmatic system on the line direction LR, and in addition with reduced extension in the LA direction and increased edge steepness.

[0103] As Fig. 15 shows, by overlapping, preferably avoiding intensity-modulating coherence effects, the LA extension can be further reduced, and an actually and not only effectively coherent intensity profile of increased edge steepness can be realized.

[0104] As shown in Fig. 16, the beam shaping can be performed simultaneously in both the KA and LA directions with a directional component and at the same time in a directionally flexible manner by preferably arranging it in an overlapping (corresponding) KA-LA far-field region or KA-LA near-field region.

[0105] In the example of Fig. 17, two overlapping multi-spot profiles are realized in the processing zone by means of polarization splitting. By varying the angle of the splitting direction, the width of the effective beam profile SP acting in the LA direction during feed is achieved while maintaining the flank steepness. The splitting can be realized by a beam splitting component, which causes an angular offset for mutually perpendicularly polarized partial beams and is preferably divided into a KA-LA-

[0106] Far-field region is rotatably arranged. Alternatively, a component rotatably arranged in an overlapping KA-LA near-field region can be used, which causes a spatial offset between perpendicularly polarized partial beams.

[0107] Beam shaping of partial spots of a multi-spot profile in both spatial directions, here combined with an intensity modulation-reducing polarization superposition (superposition of partial spots of mutually perpendicular polarization states, separated wavelength ranges and / or offset in time), can also be realized by arranging the shaping preferably in an LA-KA far-field region. In the examples in Figs. 16 to 18, the multi-spot profiles have a preferred processing direction related to the optical arrangement 10 that corresponds to the KA orientation and is oriented to the effective scanning direction. This preferred processing direction is advantageously essentially retained even when the polarization splitting is rotated.

[0108] Frequently, a preferred direction of machining or preferred machining direction on the workpiece 42 is desired. Figs. 19 to 24 show, by way of example, machining in the form of a machining line that is as narrow as possible and continues scanning, using multi-spot profiles.

[0109] Typically, the LA direction is selected along the machining line. The preferred machining direction of the multi-spot line is influenced by the astigmatic focusing (either reduced (Figs. 14 - 18) or, preferably, increased (Figs. 19 - 22)). A distance in the feed direction VR can be used to reduce disruptive effects such as heat accumulation and shielding. Without relative movement between the optical arrangement and the workpiece that deviates from the LA direction, scanning is preferably carried out in the LA direction (cf. Figs. 19, 22). Under relative movement with a directional component that deviates from the LA direction, the multi-spot profile, the LA direction and the machining line are also preferably oriented parallel and the relative movement is compensated by an adapted scanning direction SR (cf. Figs. 20, 23, 24). A variation of the relative movement speed , e . g . by changing the feed rate v Rand / or LA scan speed v LA , can be compensated for by the scan angle while maintaining the parallel alignment and the scan speed, i.e. an adjustment of the KA scan speed.

[0110] If, on the other hand, scanning is restricted to the LA direction, it is necessary to compensate for the relative movement by means of a scanning direction SR that deviates from the line and to align the multi-spot profile at an angle to the LA direction, as shown in Fig. 21. As explained in connection with Fig. 13, this results in an increased requirement for the tolerances to be maintained and, in addition to an increased machining width with reduced flank steepness, reduced flexibility in compensating for varying feed rates. The design of the optical arrangement 10 with beam shaping to form a preferred machining direction deviating from the LA or KA direction, here as an example as a line with direction LR, therefore represents a possible solution. However, the preferred machining directions are preferably oriented in the KA direction and / or LA direction.

[0111] Figs. 23 and 24 are an example of full-surface machining. The machining geometry on the workpiece 42 does not have a preferred machining direction, so the LA direction can be freely selected. It is therefore advisable to select this in an LR direction so that the scanning direction SR in the optical arrangement 19 is oriented orthogonally to the feed direction VR. This means that machining can take place in an area within the laser processing system 100 that is minimized in the feed direction. In order to increase the effect per scan with a minimized LA profile length and process-adapted fluence, or to achieve the appropriate effective fluence distribution even with a slight overlap of successive pulses and / or scans, customized beam profiles can also be advantageously used.

[0112] As an example, a connected multispot line with reduced intensity modulation in the LA direction is shown (cf. Fig. 15, 18).

[0113] Furthermore, a FlatTop beam profile can be used for full-surface machining with process-adapted fluence distribution and minimized pulse overlap, i.e., essentially single-pulse machining. In this case, the preferred machining direction does not result directly from the desired machining geometry, but indirectly: The scanning direction is selected perpendicular to the feed direction to minimize the system-specific expansion of the machining region. This results in an LA alignment adapted to the beam shape, feed rate, and other parameters, and a coupled preferred machining direction.

Claims

Patent claims 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 beam source (50) for generating an input laser beam (1); - an optical arrangement (10) for converting the input laser beam (1) into an output laser beam (3) for processing the workpiece (42), which output laser beam (3) propagates along a propagation direction (z) and which, in a working region (40), has a beam cross-section extended along a long axis (LA) of the optical arrangement (10), wherein the optical arrangement (10) comprises: • an LA focusing optics (34) for focusing a beam path (2) within the optical arrangement (10) between the input laser beam (1) and the output laser beam (3) along the long axis (LA), • an LA scanner component (36) for scanning the beam path (2) with at least one LA scanning direction component along the long axis (LA), • a KA focusing optics (28) for focusing the beam path (2) along the short axis (KA), and • a KA scanner component (22) for scanning the beam path (2) with at least one KA- Scan direction component along the short axis (KÄ); - a feed device (60) for feeding the workpiece (42) relative to the optical arrangement (10) in a feed direction (VR); and - a control device (70) configured to synchronize the scanning of the beam path (2) along the LA scanning direction component with the scanning of the beam path (2) along the KA scanning direction component. The laser processing system (100) according to claim 1, wherein the synchronization by means of the control device (70) is configured to compensate for a relative movement between the workpiece (42) and the optical arrangement (10) resulting from the advance of the workpiece (42) in the advance direction (VR) by scanning the beam path (2) with the KA scanner component (22). The laser processing system (100) according to claim 1 or 2, wherein the LA scanner component (36) and the KA scanner component (22) are scanner components that function independently of one another.Laser processing system (100) according to one of the preceding claims, wherein the LA scanner component (36) is configured to scan the beam path (2) along a preferential processing direction (VBR) parallel to the long axis (LA) such that a first angle a > 0°, in particular a > 90°, exists between an LA scanning direction and the feed direction (VR). Laser processing system (100) according to claim 4, wherein the LA scanner component (36) is configured to be at least for an average LA scanning speed v LA = B b / (t s • sin(a) ) + v R • cos (a) and / or the KA scanner component (22) at least for an average KA scanning speed v I<A = v r • sin(a) is set up, where B b a machining width on the workpiece (42) perpendicular to the feed direction (VR), t s a processing time for the processing length B b = B b / sin(a) and v Ra feed rate in the feed direction (VR). Laser processing system (100) according to claim 5, wherein the LA scanner component (36) for an LA scan field length s LA h B b / sin(a) + B s • cos (a) and / or the KA scanner component (22) for a KA scan field width SRA h B s • sin(a) is set up, where B s is a length swept during the scan. Laser processing system (100) according to one of the preceding claims, wherein the optical arrangement (10) is designed such that the beam cross-section is formed by a multi-spot profile. Laser processing system (100) according to claim 7, wherein the multi-spot profile has spots distributed along the short axis (KA) and the long axis (LA). Laser processing system (100) according to claim 7 or 8, wherein the multi-spot profile is provided with a beam cross-section that changes due to astigmatic focusing of the optical arrangement (10). resulting line direction of the beam cross-section in a Angle of attack > 0° relative to the LA scanning direction component. Laser processing system (100) according to one of the preceding claims, wherein the control device (70) is configured to adapt the laser power of the output laser beam (3) to the speed of scanning of the beam path (2). Laser processing system (100) according to one of the preceding claims, wherein the laser beam source (50) is a pulsed, in particular ultrashort pulsed, laser beam source (50). Laser processing system (100) according to claim 11, wherein the control device (70) is configured to adapt a pulse repetition frequency to the speed of the beam movement of the output laser beam (3) on the workpiece (42) and / or the scanning with the LA scanner component (36). 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).Laser processing system (100) according to one of claims 11 to 13, wherein the control device (70) is configured for position-adapted selection of laser processing parameters along the long axis (LA). Laser processing system (100) according to one of the preceding claims, wherein the LA scanner component carries a measuring beam path of an optical sensor system.

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