Method and laser system for separating a workpiece

Abstract

The invention relates to a method for breaking a workpiece (104), in which a pulsed machining laser beam (119) is provided which forms a plurality of focal elements (120), the workpiece (104) comprising a material (102) which is transparent to the machining laser beam (119), the focal elements (120) being introduced into the material (102) of the workpiece (104) and being moved relative to the material (102) parallel to a predefined feed line (150), a material modification (138), which is arranged by a relative movement of a focal element (120) introduced into the material (102) along the machining surface (152), is formed in the material (102), and wherein the machining surface (152) protrudes in a main direction (160) relative to a partial region (162) of the workpiece (104), and wherein the material (102) is subjected to a heating laser beam (142), the material (102) of the workpiece (104) being opaque to the heating laser beam (142), the heating laser beam (142) is moved relative to the material (102) along a heating laser beam feed line (158), as a result of which the material (102) is broken along the machining surface (152), the heating laser beam feed line (158) extending parallel to the feed line (150) and being spaced apart from the feed line (150) by a location offset ([delta] d) that is anti-parallel to the main direction (160), and wherein the heating laser beam feed line (158) extends parallel to the feed line (150) and is offset ([delta] d) from the feed line (150) by a location offset ([delta] d) that is offset ([delta] d) from the main direction (160). The location offset ([Delta] d) is at least 10% and at most 50% of the diameter (d1) of the heating laser beam.

Description

Technical Field

[0001] The present invention relates to a method and a laser system for severing / splitting a workpiece. Background Art

[0002] WO 2022 / 167254 A1 and WO 2022 / 167257 A1 respectively disclose a method and a device for laser processing a transparent workpiece, wherein the workpiece is loaded with a plurality of focal elements for laser processing.

[0003] JP 2020 004 889A discloses a method for severing and in particular chamfering a transparent material, wherein a spatial light modulator is used to generate a plurality of focal points for laser processing the material.

[0004] US2020 / 0147729 A1 and US2020 / 0361037 A1 respectively disclose a method for forming an edge region with an inclined chamfer or a rounded corner on a transparent material using a laser beam.

[0005] EP 3 597 353 A1, EP 3 487 656 B1 and WO 2016 / 089799 A1 disclose a method for severing a transparent material using a non-diffracting laser beam. Summary of the Invention

[0006] It is an object of the present invention to provide the method and the laser system mentioned at the beginning, which enable high-quality severing of the material at the severing surface, wherein the severing surface has a pre-given geometry.

[0007] In the method mentioned at the beginning, according to the present invention, this object is achieved by: providing a pulsed processing laser beam that forms a plurality of focal elements, wherein the workpiece comprises a material that is transparent to the processing laser beam, the focal elements are introduced into the material of the workpiece and move relative to the material parallel to a pre-given feed line, wherein, by the relative movement of the focal elements introduced into the material, a material modification is formed in the material along the processing surface, and wherein the processing surface protrudes in a main direction (Vorzugsrichtung) relative to a partial region of the workpiece, and heating the material with a heating laser beam, wherein the material of the workpiece is opaque to the heating laser beam, wherein the heating laser beam moves relative to the material along a heating laser beam feed line, thereby severing the material along the processing surface, wherein the heating laser beam feed line extends parallel to the feed line and is spaced apart from the feed line by a location offset (Ortsversatz) that is anti-parallel to the main direction, and wherein the location offset is at least 10% and at most 50% of the heating laser beam diameter.

[0008] It has been shown that the incidence of the heating laser beam with the aforementioned site offset causes suitable crack formation between the material modification portions arranged on the machining surface. Then, this crack formation causes the material to be segmented along a segmentation plane, which has a geometry corresponding to the machining surface. In addition, the segmentation plane is formed with improved quality in this way, wherein the segmentation plane in particular has a reduced roughness.

[0009] In particular, it can be provided that the site offset of the heating laser beam feed line relative to the feed line of the focus element is at least 15%, and in particular at least 20%, and in particular at least 25% of the diameter of the heating laser beam. The aforementioned advantages are thereby achieved.

[0010] For the reasons mentioned above, it can be advantageous for the machining laser beam and / or the heating laser beam to be coupled into the material of the workpiece through the first outer side of the workpiece, wherein the thickness direction of the workpiece is oriented transversely to and in particular perpendicular to the first outer side.

[0011] In particular, the machining laser beam and / or the heating laser beam are directed onto the first outer side for coupling into the material. In particular, the heating laser beam incident on the first outer side is divergent or collimated, and in particular not focused and / or not converging.

[0012] In particular, the workpiece is configured in the form of a plate and / or a sheet and / or a disk. In particular, the workpiece has a first outer side and a second outer side spaced apart from the first outer side in the thickness direction of the workpiece, wherein the first outer side and the second outer side are parallel to each other or oriented transversely to each other, and / or wherein the first outer side and the second outer side are spaced apart from each other by the thickness of the workpiece and in particular by a constant thickness.

[0013] In particular, the first outer side is the outer side of the workpiece onto which the machining laser beam and / or the heating laser beam first impinge in terms of their respective beam propagation directions.

[0014] In particular, the machining laser beam is oriented perpendicular to the first outer side. In particular, the heating laser beam and in particular the longitudinal central axis of the heating laser beam are oriented perpendicular to the first outer side.

[0015] For the reasons mentioned above, it is advantageous to load the partial region (the machining surface projects in the main direction with respect to this partial region) with the heating laser beam. In particular, this ensures a compliant segmentation of the workpiece along the machining surface projecting in the main direction.

[0016] For the same reason, it is advantageous for the heating laser beam feed line to extend in the partial region (the machining surface projects in the main direction with respect to this partial region).

[0017] In particular, it can be set that the main direction is oriented perpendicular to a plane that is parallel to the feed line and extends parallel to the thickness direction of the workpiece to be severed.

[0018] In particular, the thickness direction is oriented parallel to the beam propagation direction of the machining laser beam and / or the heating laser beam.

[0019] In particular, the main direction points from the inside of the partial region (the machining surface protrudes in the main direction with respect to this partial region) towards the direction of the protrusion formed by the machining surface with respect to this partial region and / or towards the direction of the projection formed by the machining surface with respect to this partial region.

[0020] In particular, it can be set that the machining surface extends continuously between the first outer side and the second outer side of the workpiece, and the second outer side is spaced apart from the first outer side in the thickness direction. In particular, this enables the workpiece to be severed continuously along the machining surface.

[0021] In particular, material modification parts are arranged in the material on the machining surface, and these material modification parts enable the material to be continuously and / or uninterruptedly severed between the first outer side and the second outer side by means of the heating laser beam.

[0022] It can be advantageous that the heating laser beam has a diameter of at least 0.5 mm and at most 5 mm, and in particular at least 2 mm and at most 4 mm. This enables the workpiece to be severed with high quality at the severance surface. In particular, the diameter of the heating laser beam should be understood as the diameter at which the heating laser beam hits the workpiece and / or the diameter that the heating laser beam has on the first outer side of the workpiece.

[0023] For example, the position offset anti-parallel to the main direction is between 200 μm and 1.5 mm.

[0024] It can be advantageous that the machining laser beam has a wavelength of at least 300 nm and at most 1500 nm. For example, the wavelength is 1030 nm or 515 nm. This enables the focus element formed by means of the machining laser beam to be introduced into various materials such as glass materials and / or plastic materials that are transparent to laser beams in this wavelength range or having these wavelengths.

[0025] In particular, it can be set that the machining laser beam has ultrashort laser pulses. This enables the focus element to be used to form material modification parts in a technically simple manner, and these material modification parts enable the material to be severed using the machining laser beam. For example, the pulse duration of the laser pulse is between 10 fs and 50 ns.

[0026] It can be advantageous that the heating laser beam has a wavelength of at least 9 μm and at most 11 μm. This enables the workpiece to be effectively severed by loading the material of the workpiece with the heating laser beam.

[0027] In particular, it can be set that the heating laser beam is a pulsed laser beam. However, in principle, it can also be that the heating laser beam is a continuous-wave laser beam.

[0028] In particular, the power of the heating laser beam is between 20 W and 35 W.

[0029] In particular, the feed rate at which the heating laser beam moves along the feed line of the heating laser beam is between 2 m / min and 3 m / min.

[0030] In particular, it can be set that the workpiece to be severed has a thickness between 10 μm and 10 mm, preferably between 100 μm and 1 mm, and particularly preferably between 450 μm and 650 μm. The method according to the invention can be used to sever workpieces with a thickness in the mentioned range with a particularly good fracture surface.

[0031] For the same reason, it can be advantageous if the extension length of the machining surface oriented parallel to the main direction is at least 5% and at most 70%, preferably at least 15% and at most 35%, of the thickness of the workpiece to be severed. For example, the extension length is between 25 μm and 400 μm.

[0032] In particular, by severing the material of the workpiece along the machining surface, a workpiece section corresponding to the partial region of the workpiece (the machining surface projects in the main direction with respect to this partial region) is formed. This workpiece section has a fracture surface corresponding to the machining surface, wherein, in particular, the cross-sectional geometry of the machining surface corresponds to the cross-sectional geometry of the fracture surface.

[0033] In particular, it can be set that when observed in a section perpendicular to the feed line and / or in a projection perpendicular to the feed line, the focus element is arranged along a pre-given machining line that defines the cross-sectional shape of the machining surface and / or defines the cross-sectional shape of the fracture surface produced by severing the material along the machining surface.

[0034] It can be set that the angle of attack between the machining line and the first outer side of the workpiece is at least sectionally at least 1° and / or at most 90°, and in particular at most 89°. The machining laser beam is coupled into the material of the workpiece through this first outer side to form the focus element. Thus, depending on the selected angle of attack, for example, a vertical cut can be made on the workpiece, or the workpiece can be chamfered at a specific angle.

[0035] That the machining line has at least sectionally a specific angle of attack or an angle-of-attack range should in particular be understood as meaning that the machining line has at least one section that has this angle of attack or this angle-of-attack range.

[0036] In particular, the angle of attack can be at least 10° and / or at most 80°, preferably at least 30° and / or at most 60°, and particularly preferably at least 40° and / or at most 50°.

[0037] In particular, it can be provided that the angle of attack of the processing line is at least sectionally constant and / or the processing line comprises a plurality of sections with different angles of attack.

[0038] In particular, it can be provided that the processing line is at least sectionally straight and / or the processing line is at least sectionally curved.

[0039] For example, by configuring the processing line as a curve, a rounded section can be cut from the workpiece. For example, this enables rounded edges to be produced.

[0040] When the processing line is implemented as a curve, the processing line is assigned, for example, a specific range of angles of attack, which the processing line has with respect to the outer side of the workpiece.

[0041] For example, the at least one processing line has a total length between 10 μm and 10,000 μm and in particular between 100 μm and 1,000 μm and in particular between 400 μm and 600 μm. This enables workpieces with a thickness in the mentioned range to be severed.

[0042] It can be advantageous to form focus elements by splitting an input laser beam into a plurality of sub-beams by means of a beam splitting element and focusing the sub-beams coupled out from the beam splitting element. Thus, a plurality of focus elements can be formed by means of the input laser beam, where, in particular, the properties of the focus elements, such as their geometry and / or their intensity profile, are defined by and / or based on the input laser beam.

[0043] It can be advantageous that the splitting of the input laser beam by means of the beam splitting element is carried out by and / or includes phase imposition on the beam cross-section of the input laser beam. Thereby, for example, the focus elements can be formed as copies of one another. In particular, this enables the focus elements to be introduced into the workpiece material at different positions and / or at different distances in a technically simple manner.

[0044] It can be provided that the splitting of the input laser beam is carried out only by phase imposition on the beam cross-section of the input laser beam.

[0045] In particular, the phase imposition is carried out in the transverse direction of the input laser beam. The transverse direction lies in a plane oriented perpendicular to the beam propagation direction of the input laser beam.

[0046] Alternatively or additionally it can be provided that the splitting of the input laser beam takes place by polarization splitting by means of a beam splitting element or comprises polarization splitting. Here, for example, adjacent focus elements can each be formed with different polarization states. In particular, this prevents interference between adjacent focus elements, so that they can be arranged at a particularly short distance relative to one another.

[0047] In principle it is possible to use both phase addition and polarization splitting to split the input laser beam.

[0048] The material modifications introduced into the transparent material by the ultrashort laser pulses are divided into three different categories, see “Ultrafast Processes for Bulk Modification of Transparent Materials” by K. Itoh et al., MRS Bulletin, Volume 31, page 620 (2006): Type I is an isotropic refractive index change, Type II is a birefringent refractive index change, and Type III is the so-called “Void” or cavity. The type of material modification produced by a given focus element depends on the laser parameters of the laser beam forming the corresponding focus element, such as the pulse duration, wavelength, pulse energy and repetition frequency of the laser beam. In addition, the type of modification depends on the properties of the material, in particular such as the electronic structure and thermal expansion coefficient of the material, and on the numerical aperture (NA) used when the laser beam is focused into the corresponding focus element.

[0049] The isotropic refractive index change of Type I is attributed to locally limited melting by the laser pulse and rapid solidification of the transparent material. For example, in the case of fused silica, if the fused silica is rapidly cooled from a higher temperature, the density and refractive index of the material become higher. Thus, if the material in the volume controlled by the focus element is melted and then rapidly cooled, the fused silica has a higher refractive index in the region of the material modification than in the unmodified region.

[0050] The birefringent refractive index change of Type II can be caused, for example, by the interference between the ultrashort laser pulse and the electric field of the plasma generated by the laser pulse. This interference results in a periodic modulation of the electron plasma density, which leads to the birefringent properties of the transparent material, i.e., the direction-dependent refractive index, upon solidification. For example, Type II modification is also accompanied by the formation of so-called “nano gratings”.

[0051] Type III modified voids (cavities) can in particular be generated with high laser pulse energies. In this context, the formation of the voids is attributed to the explosively expanding highly excited evaporated material from the focal volume into the surrounding material. This process is also referred to as a microexplosion. Since this expansion occurs within the bulk of the material, the microexplosion leaves behind a less dense or hollow core (void), or microscopic defects in the sub-micron or atomic range, which is surrounded by a compressed material cladding. The compression at the shock front of the microexplosion generates stresses in the transparent material, which typically lead to the formation of spontaneous cracks or promote crack formation.

[0052] Thus, when it comes to the introduction of Type III modification, there is in any case a less dense or hollow core or rather a defect. Exemplarily, in sapphire in the case of Type III modification, regions of lower density are generated by microexplosion rather than voids.

[0053] In particular, the formation of voids may also be accompanied by Type I and Type II modifications. For example, Type I and Type II modifications may occur in regions with less stress around the introduced laser pulse. When introducing Type III modification, it is not possible to completely prevent or avoid the formation of Type I and Type II modifications. Thus, it is unlikely to find a "pure" Type III modification.

[0054] It can be advantageous to form a material modification in the material by loading the material of the workpiece with focal elements, where the material modification is accompanied by crack formation in the material, and / or where the material modification is a Type III material modification. In particular, the severance of the material can be achieved with the aid of these material modifications.

[0055] According to the invention, there is provided a laser system for severing a workpiece as mentioned at the beginning, the laser system comprising: a laser beam source, a beam splitting element, and a focusing optics, which together are configured to provide a processing laser beam that forms a plurality of focal elements for introduction into the material of the workpiece; a feed device for performing a relative movement of the focal elements relative to the material of the workpiece parallel to a pre-given feed line so as to form a material modification arranged along a processing surface in the material, wherein it is provided that: the processing surface protrudes in a main direction with respect to a partial region of the workpiece; a further laser beam source for providing a heating laser beam, wherein the feed device is configured to move the heating laser beam relative to the material along a heating laser beam feed line so as to sever the material along the processing surface, wherein the heating laser beam feed line extends parallel to the feed line and is offset from the feed line at a location anti-parallel to the main direction and spaced apart from the feed line, and wherein the location offset is at least 10% and at most 50% of the diameter of the heating laser beam.

[0056] In particular, the laser system according to the invention has one or more further features and / or advantages of the method according to the invention. Advantageous embodiments of the laser system according to the invention have been described in connection with the method according to the invention.

[0057] In particular, the method according to the invention can be carried out by means of the laser system according to the invention, or the method according to the invention is carried out by means of the laser system according to the invention.

[0058] In particular, the laser system according to the invention is suitable for severing the following workpieces, which have a material transparent to the machining laser beam and / or a material opaque to the heating laser beam.

[0059] It can be advantageous if the beam splitting element is configured as a 3D beam splitting element or includes a 3D beam splitting element. It can be provided here that the input laser beam is split by phase addition on the beam cross-section of the input laser beam, and in particular only by phase addition on the beam cross-section of the input laser beam.

[0060] It can be advantageous if the beam splitting element is configured as a polarization beam splitting element or includes a polarization beam splitting element.

[0061] For example, the beam splitting element includes a plurality of components and / or functions. It can be provided that the beam splitting element includes both a 3D beam splitting element and a polarization beam splitting element.

[0062] The transparent material should be understood as a material through which at least 70%, and in particular at least 80%, and in particular at least 90% of the laser energy of the machining laser beam is transmitted. For example, if the machining laser beam is directed onto the first outer side of the workpiece, at least 70%, and in particular at least 80%, and in particular at least 90% of the laser energy of the machining laser beam is transmitted at the second outer side of the workpiece, which is spaced apart from the first outer side in the beam propagation direction and / or the thickness direction.

[0063] The opaque and / or non-transparent material should be understood as a material through which at most 10%, and in particular at most 5%, and in particular at most 3% of the laser energy of the heating laser beam is transmitted. For example, if the heating laser beam is directed onto the first outer side of the workpiece, at most 10%, and in particular at most 5%, and in particular at most 3% of the laser energy of the machining laser beam is transmitted at the second outer side of the workpiece, which is spaced apart from the first outer side in the beam propagation direction and / or the thickness direction.

[0064] In particular, the focal element should be understood as a radiation region having a specific spatial extent and intensity distribution. For determining the spatial dimensions of a defined focal element, such as the diameter of the focal element, only the intensity values of the intensity distribution that exceed a specific intensity threshold are considered. In this regard, for example, the intensity threshold is selected such that the values below this intensity threshold have such a low intensity that they are no longer relevant for interacting with the material to form a material modification. For example, the intensity threshold is 50% of the global intensity maximum of the focal element.

[0065] In particular, a defined focal element is correspondingly assigned a spatially interacting region in which the focal element interacts with the material of the workpiece when the focal element is introduced into the workpiece.

[0066] In particular, the focal element introduced into the material interacts with the material by non-linear absorption. In particular, a material modification is generated in the material by means of the focal element based on non-linear absorption.

[0067] In particular, it can be set that, according to the foregoing definition, each focal element has a maximum spatial extent of at least 0.5 μm and / or at most 30 μm, preferably at least 2 μm and / or at most 10 μm. In particular, the maximum spatial extent of the interacting region assigned to a defined focal element and interacting with the material of the workpiece is at least 0.5 μm and / or at most 30 μm and preferably at least 2 μm and / or at most 10 μm.

[0068] The maximum spatial extent of a defined focal element should in particular be understood as the maximum spatial extent of the focal element in any spatial direction.

[0069] In particular, the respective maximum spatial extent of the focal element is less than 20% of the material thickness and preferably less than 10% of the material thickness and particularly preferably less than 5% of the material thickness.

[0070] In particular, the focal element has a diffracted beam profile. In particular, the focal element is configured to be diffraction-limited. For example, a defined focal element has a Gaussian shape and / or a Gaussian intensity profile. However, it can also be that the focal element has a non-diffracted and in particular Bessel-like beam profile.

[0071] In particular, the processing laser beam has a diffracted beam profile and / or a Gaussian beam profile.

[0072] In particular, adjacent focal elements have a distance of at least 3 μm and / or at most 70 μm, where the distance direction assigned to this distance is oriented perpendicular to the feed line of the focal element and / or perpendicular to the feed direction.

[0073] In particular, the material modification portions adjacent to each other on the machining surface have a distance between 3 μm and 70 μm, wherein the distance direction assigned to this distance is perpendicular to the feed direction of the focus element and / or oriented along the feed line.

[0074] In particular, the material modification portions adjacent to each other on the machining surface have a distance between 1 μm and 30 μm, wherein the distance direction assigned to this distance is parallel to the feed line of the focus element and / or oriented along the feed direction.

[0075] In particular, the material modification portions adjacent to each other on the machining surface have such a distance that crack formation occurs between the adjacent material modification portions and / or the material can be severed on the machining surface by means of a heating laser beam.

[0076] In particular, the machining laser beam has an average power of at least 1 W to 1 kW. For example, the machining laser beam comprises pulses having a pulse energy of at least 10 μJ and / or at most 50 mJ. It can be provided that the machining laser beam comprises single pulses or bursts, wherein the bursts have 2 to 20 sub-pulses and in particular have a time interval of approximately 20 ns.

[0077] The term "at least a portion of the focus elements" can mean a portion of the focus elements or the total amount of the focus elements, i.e. all focus elements.

[0078] In particular, the term "at least approximately" or "approximately" should generally be understood to mean a deviation of not more than 10%. Unless otherwise specified, the term "at least approximately" or "approximately" should in particular be understood to mean that the actual value and / or distance and / or angle deviate from the ideal value and / or distance and / or angle by not more than 10%. Description of the Drawings

[0079] The following description of the preferred embodiment serves to explain the present invention in more detail with reference to the drawings.

[0080] In the drawings:

[0081] Figure 1 A schematic representation of an embodiment of a laser system for severing a workpiece is shown;

[0082] Figure 2 A schematic cross-sectional representation of a cross-section of the material of the workpiece is shown, wherein the material is loaded with a plurality of focus elements to form material modification portions, wherein the focus elements are arranged along a machining line having different straight sections;

[0083] Figure 3 A schematic cross-sectional representation of a cross-section of the workpiece is shown, wherein material modification portions are generated by loading the workpiece with focus elements, and crack formation of the material is accompanied by the material modification portions;

[0084] Figure 4a shows a cross-sectional representation of the simulated intensity distribution of focus elements for laser machining of a workpiece, wherein,

[0085] adjacent focus elements are spaced apart from each other by a distance of approximately 17.5 μm;

[0086] Figure 4b shows a cross-sectional representation of the simulated intensity distribution of focus elements for laser machining of a workpiece, wherein,

[0087] adjacent focus elements are spaced apart from each other by a distance of approximately 8.0 μm;

[0088] Figure 5a shows a schematic perspective view of a workpiece formed with a material modification portion that extends along a machining line and / or a machining surface;

[0089] Figure 5b shows a schematic perspective view of two workpiece segments formed by Figure 5a severing the workpiece along a machining line and / or a machining surface; and

[0090] Figure 6 shows a schematic cross-sectional representation of a cross-section of the material of a workpiece, wherein the material is loaded with a plurality of focus elements to form a material modification portion, wherein the focus elements are positioned along an arcuate machining line.

[0091] In all the figures, elements that are the same or have equivalent functions are provided with the same reference numerals. The figures shown are not drawn to scale. Detailed Description

[0092] Figure 1 shows an embodiment of a laser system for severing a workpiece and is designated therein by 100. With the aid of the laser system 100, locally (lokalisierte) material modification portions, such as defects in the submicron or atomic range, can be generated in the material 102 of the workpiece 104, which lead to weakening of the material. The workpiece 104 can be severed at these material modification portions, wherein the workpiece 104 can, for example, be divided into two workpiece segments or a workpiece segment can be removed from the workpiece 104.

[0093] In particular, with the aid of the laser system 100, the material modification portions can be introduced into the material 102 at an attack angle such that the edge region of the workpiece 104 can be chamfered or beveled by removing a workpiece segment from the workpiece 104.

[0094] The laser system 100 includes a beam splitting element 106, into which an input laser beam 108, in particular a collimated input laser beam, is coupled. The input laser beam 108 is provided by a laser beam source 110 of the laser system 100. In particular, the input laser beam 108 is a pulsed laser beam and / or an ultrashort pulsed laser beam.

[0095] It can be provided that the laser beam source 110 includes a hollow fiber (not shown), from which the laser beam formed by the laser beam source 110 emerges. Then, for example, a collimating optical device (not shown) of the laser beam source 110 is used to collimate the laser beam to form the input laser beam 108.

[0096] The input laser beam 108 is to be understood as meaning a beam cluster, which includes a plurality of light beams, in particular a plurality of light beams extending in parallel. The input laser beam 108 has a transverse beam cross-section 112 and / or a transverse beam extension, and the input laser beam 108 impinges on the beam splitting element 106 with this transverse beam cross-section and / or transverse beam extension.

[0097] In particular, the input laser beam 108 impinging on the beam splitting element 106 has at least an approximately planar wavefront 114.

[0098] By means of the beam splitting element 106, the input laser beam 108 is split into a plurality of sub-beams 116 or sub-beam clusters. In the example shown in Figure 1 two different sub-beams 116a and sub-beam 116b or sub-beam clusters are schematically shown.

[0099] In particular, the beam splitting element 106 is configured as a far-field beam shaping element. In particular, the sub-beam cluster coupled out from the beam splitting element 106 has a divergent beam profile and / or propagates in the manner of a spherical wave.

[0100] In order to focus the sub-beams 116 coupled out from the beam splitting element 106, the laser system 100 includes a focusing optical device 118, into which the sub-beams 116 are coupled. For example, the focusing optical device 118 has one or more lens elements. For example, the focusing optical device 118 is configured as a microscope objective.

[0101] For example, the focusing optical device 118 has a focal length between 5 mm and 50 mm.

[0102] In particular, the beam splitting element 106 is arranged at least approximately in the back focal plane of the focusing optical device 118.

[0103] In particular, the different sub-beams 116 strike the focusing optical element 118 with a position offset and / or an angular offset. These sub-beams 116 are focused by means of the focusing optical element 118, where the sum of the sub-beams 116 focused by means of the focusing optical element 118 is referred to as the processing laser beam 119. By focusing the sub-beams, a plurality of focal elements 120 are formed, which are each arranged at different spatial positions. In principle, adjacent focal elements 120 can overlap spatially in sections.

[0104] Therefore, the processing laser beam 119 should be understood as encompassing the sub-beams emerging from the processing optical element 118 that form the focal elements 120.

[0105] In particular, a plurality of sub-beams 116 are respectively assigned to a specific focal element 120, that is, a specific focal element 120 is formed by a plurality of sub-beams 116 striking the focusing optical element 118.

[0106] In particular, the focal element 120 should be understood as a focused radiation region, such as a focal spot and / or a focus. In particular, each focal element 120 has a specific geometric shape and / or a specific intensity profile, where the geometric shape is understood, for example, as the spatial shape and / or the spatial extent of the respective focal element 120.

[0107] The geometric shape and / or the intensity profile of a specific focal element 120 is hereinafter referred to as the focal distribution 121 of the focal element 120. The focal distribution 121 is a property of the respective focal element 120 and describes the respective shape and / or the intensity profile of the focal element. In particular, the plurality of focal elements 120 formed or all focal elements 120 have the same focal distribution.

[0108] The focal distribution of the formed focal elements 120 is defined by the input laser beam 108, and the input laser beam is split using the beam splitting element 106 to form the focal elements 120. If the input laser beam 108 is focused before being coupled into the beam splitting element 106, a single focal element will thus be formed, which has the focal distribution assigned to the input laser beam 108.

[0109] For example, the input laser beam 108 can have a Gaussian beam profile. In this case, by focusing the input laser beam 108, a focal element is formed, the focal distribution 121 of which has a Gaussian shape and / or a Gaussian intensity profile.

[0110] Alternatively, for example, it can be provided that the input laser beam 108 is assigned a Bessel-like beam profile, such that by focusing the input laser beam 108, a focal element is formed, the focal distribution 121 of which has a Bessel-like shape and / or a Bessel-like intensity profile.

[0111] A sub - beam 116 or a cluster of sub - beams formed by splitting an input laser beam 108 by means of a beam - splitting element 106 is assigned a focus distribution of the input laser beam 108 such that by focusing the sub - beam 116, a focus element 120 having this focus distribution and / or having a focus distribution based on this focus distribution is formed.

[0112] In Figure 1 the example shown, the input laser beam 108 has a Gaussian beam profile, i.e., the input laser beam 108 is assigned a focus distribution having a Gaussian shape and / or a Gaussian intensity profile. Here, the focus elements 120 each have, for example, a focus distribution 121 which has this Gaussian shape and / or this Gaussian intensity profile or has a shape and / or intensity profile based on this Gaussian shape and / or this Gaussian intensity profile (see also Figure 4a and Figure 4b ).

[0113] For example, if the input laser beam 108 is assigned a Bessel - like beam profile, the focus elements 120 formed for laser - machining the workpiece 104 each have a focus distribution 121 which has this Bessel - like beam profile or has a beam profile based on this Bessel - like profile. Thus, the focus elements 120 can each be formed, for example, with a focus distribution having an elongated shape and / or an elongated intensity profile.

[0114] It can be provided that the laser system 100 has a beam - shaping device 122 (schematically shown in Figure 1 ) for beam - shaping the input laser beam 108. For example, the beam - shaping device 122 is arranged upstream of the beam - splitting element 106 with respect to the beam propagation direction 124 of the input laser beam 108 and / or is arranged between the laser beam source 110 and the beam - splitting element 106.

[0115] In the present case, the beam propagation direction should be understood as the main beam propagation direction and / or the average propagation direction of the laser beam or the beam cluster. The beam propagation direction corresponds in particular to the direction of the Poynting vector assigned to the laser beam or the beam cluster.

[0116] By means of the beam - shaping device 122, a specific beam profile can be assigned to the input laser beam 108, and the beam profile defines the focus distribution 121 of the focus element 120.

[0117] For example, the beam - shaping device 122 can be configured to form a laser beam having a quasi - non - diffracting and / or Bessel - like beam profile from a laser beam having a Gaussian beam profile. For this purpose, the beam - shaping device 122 is, for example, or includes a diffractive optical element and / or an axicon element and / or an axicon - like element.

[0118] Here, the input laser beam 108 coupled into the beam splitting element 106 has a quasi-non-diffracting or Bessel-like beam profile. Accordingly, the focal element 120 also has this quasi-non-diffracting or Bessel-like beam profile or a beam profile based on this beam profile.

[0119] Regarding the definition and implementation of quasi-non-diffracting and / or Bessel-like beams, reference is made to the publication “Structured Light Fields: Applications in Optical Trapping, Manipulation and Organisation”, M. Springer Science&Business Media (2012), ISBN 978-3-642-29322-1, and also to the scientific publications “Bessel-like optical beams with arbitrary trajectories”, I Chremmos et al., Optics Letters, Vol. 37, No. 23, December 1, 2012 and “Generalized axicon-based generation of nondiffracting beams”, K. Chen et al., arXiv:1911.03103v1 [physics.optics], November 8, 2019.

[0120] By splitting the beam using the beam splitting element 106, the focal elements 120 are formed to be identical to each other and / or to be copies of each other, respectively.

[0121] Each of the formed focal elements 120 is assigned a specific site position x0, y0, z0 at which the respective focal element 120 is arranged with respect to the material 102 of the workpiece 104 ( Figure 2 ). In particular, the site position of the focal element 120 is to be understood as the position of its spatial center point and / or center of gravity. In addition, each of the formed focal elements 120 is assigned a specific intensity I. Accordingly, the site positions x0, y0, z0 and the intensity I of the respective focal element 120 can be defined by means of the beam splitting element 106.

[0122] In particular, a plurality or all of the focal elements 120 formed for laser processing of the workpiece 104 have the same intensity I. However, it is also possible that a plurality of the formed focal elements 120 have different intensities I.

[0123] In particular, by means of the beam splitting element 106, the respective distances d and / or the respective positional offsets between adjacent focus elements 120 can be adjusted in components in three spatial directions and / or spatial dimensions (in the x, y, and z directions in the example shown in Figure 1 and Figure 2 ).

[0124] The distance d between adjacent focus elements 120 is, for example, between 3 μm and 70 μm.

[0125] The beam splitting element 106 is preferably configured as a 3D beam splitting element or includes a 3D beam splitting element. Thus, the focus elements 120 can be formed, for example, in such a way that they are identical to each other and / or they are copies of each other.

[0126] Regarding the technical implementation and properties of the beam splitting element 106 implemented as a 3D beam splitting element, reference is made to the scientific publication "Structured light for ultrafast laser micro-and nanoprocessing", D. Flamm et al., arXiv:2012.10119v1 [physics.optics], December 18, 2020. Herein, the entire content thereof is expressly incorporated by reference.

[0127] In one embodiment of the beam splitting element 106, the beam splitting element 106 is implemented, for example, as a 3D beam splitting element, in which, for beam splitting, a defined transverse phase distribution is assigned to the transverse beam cross-section 112 of the input laser beam 108. The transverse beam cross-section and the transverse phase distribution should be particularly understood as the beam cross-section and the phase distribution in the plane that is transverse and in particular perpendicular to the beam propagation direction 124 of the input laser beam 108.

[0128] The focus elements 120 are formed by the interference of the focused sub-beams 116, where, for example, constructive interference, destructive interference, or an intermediate case such as partial constructive interference or partial destructive interference can occur.

[0129] In order to form the focus elements 120 at the respective positions x0, y0, z0 and / or at the respective distances d, the phase distribution assigned by means of the beam splitting element 106 has a specific grating component and / or an optical lens component for each focus element 120.

[0130] Due to the grating component, after focusing the sub-beams 116, corresponding site offsets of the formed focus elements 120 are generated in the first spatial direction and / or the second spatial direction (such as in the x direction and / or the y direction). Due to the optical lens component, the sub-beams 116 or the sub-beam clusters strike the focusing optical device 118 at different angles or with different degrees of convergence or divergence, which generates a site offset in the third spatial direction, for example in the z direction, after focusing.

[0131] The intensity I of the corresponding focus elements 120 is determined by the phase positions of the focused sub-beams 116 relative to each other. These phase positions can be defined by the aforementioned grating component and optical lens component, and can be selected relative to each other when constructing the beam splitting element 106 such that the focus elements 120 respectively have a desired intensity.

[0132] Alternatively or additionally, it can be provided that the beam splitting element 106 is constructed as a polarization beam splitting element or can include a polarization beam splitting element. In this case, the input laser beam 108 is polarized and split into beams by means of the beam splitting element 106, and these beams respectively have one of at least two different polarization states.

[0133] In particular, the mentioned polarization states should be understood as linearly polarized states, where, for example, two different polarization states are set and / or polarization states oriented perpendicular to each other are set.

[0134] In particular, the polarization state is such that the electric field is oriented in a plane perpendicular to the beam propagation direction of the polarized beam (transverse electric field).

[0135] For polarization beam splitting, the beam splitting element 106 includes, for example, a birefringent lens element and / or a birefringent wedge element. The birefringent lens element and / or the birefringent wedge element are made of, for example, a quartz crystal or include a quartz crystal.

[0136] Regarding the working mode and implementation of the beam splitting element 106 as a polarization beam splitting element, reference is made to DE 102020207 715A1 and DE 10 2019 217 577 A1.

[0137] By polarization beam splitting, in particular, the sub-beams 116 can be formed to have different polarization states. By focusing these sub-beams 116 by means of the focusing optical device 118, the focus elements 120 can be formed respectively by beams having a specific polarization state. Therefore, the focus elements 120 can be respectively assigned a specific polarization state and / or can be implemented to have a specific polarization state.

[0138] In particular, by means of polarization beam splitting by the beam splitting element 106, the focal elements 120 can be arranged and formed in such a way that adjacent focal elements 120 have different polarization states, respectively.

[0139] For laser processing of the workpiece 104, the focal elements 120 are introduced into the material 102 of the workpiece 104 and moved relative to the material 102 in the feed direction 126, where the focal elements 120 are moved in particular in the feed direction 126 at a specific feed rate. In the example shown, the feed direction 126 corresponds to the y-direction.

[0140] To perform the relative movement of the focal elements 120 relative to the material 102, the laser system 100 includes a feed device 127 (schematically shown in Figure 1 ). The feed device 127 is configured to move the focal elements 120 through the material 102 in the feed direction 126 at a defined feed rate.

[0141] For example, the feed device 127 can be implemented by means of a workpiece support configured to move the workpiece 104 arranged thereon relative to the focal elements 120. In principle, it is also possible to move the focal elements 120 relative to the material 102. For this purpose, for example, the laser system 100 or components of the laser system 100 are moved relative to the material 102.

[0142] For example, the coupling-in of the focal elements 120 introduced into the material 102 for laser processing of the workpiece 104 is carried out through the first outer side 130 of the workpiece 104.

[0143] For example, the workpiece 104 is configured in the form of a plate and / or sheet and / or disk. For example, the second outer side 132 of the workpiece 104 is arranged spaced apart from the first outer side 130 in the thickness direction 134 and / or depth direction of the workpiece 104. The second outer side 132 is oriented parallel to or transverse to the first outer side 130.

[0144] The material 102 of the workpiece 104 has, for example, an at least approximately constant thickness D relative to the thickness direction 134, where the thickness D is, for example, 550 μm.

[0145] The thickness direction 134 should be understood as the direction of the distance between the first outer side 130 and the second outer side 132.

[0146] The feed direction 126 is oriented transversely to and in particular perpendicular to the thickness direction 134 of the workpiece 104 and / or the beam propagation direction 124.

[0147] The formed focal elements 120 are arranged such that they are positioned along a defined processing line 136 (see Figure 2), wherein the machining line 136 lies in a plane oriented perpendicular to the feed direction 126. The machining line 136 corresponds to the target geometry with which the material 102 is to be severed.

[0148] The respective distances d and intensities I of the focus elements 120 arranged along the machining line 136 are selected such that a material modification 138 is formed by loading the material 102 with the focus elements 120 and moving the focus elements 120 through the material 102 Figure 3 ), the material modification 138 enabling the material to be severed along this machining line 136 or along a machining surface corresponding to this machining line 136.

[0149] In Figure 2 and Figure 3 the focus element 120 and the material modification 138 are respectively shown in a section of the workpiece 104 oriented perpendicular to the feed direction 126.

[0150] It is provided that the machining line 136 extends continuously and / or without interruption between the first outer side 130 and the second outer side 132. The focus elements 120 are arranged continuously and / or without interruption along the machining line 136 in order to produce a material modification 138 arranged along the machining line 136, the material modification 138 enabling the material 102 to be severed continuously between the first outer side 130 and the second outer side 132.

[0151] The machining line 136 can have a plurality of different sections 140. For example, in the example shown in Figure 2 the machining line 136 has a first section 140a, a second section 140b and a third section 140c, wherein, with respect to the thickness direction 134, the second section 140b adjoins the first section 140a and the third section 140c adjoins the second section 140b.

[0152] The machining line 136 does not have to be constructed as continuous and / or differentiable. For example, the machining line 136 can have discontinuities.

[0153] For example, the machining line 136 and / or the different sections 140 of the machining line 136 can be formed as straight lines or curves. For example, the machining line can be formed as an arc or a circular arc.

[0154] The respective distances d of the focus elements 120 provided for laser machining of the workpiece 104 can be selected differently for different focus elements 120 and / or for different pairings of the focus elements 120. However, in principle it is also possible that for all focus elements 120 provided for laser machining of the workpiece 104 the respective distances d are at least approximately the same.

[0155] For example, it can be set that different sections 140 of the processing line 136 can be respectively assigned focus elements 120 with different distances d. Herein, in particular, the distances d of the focus elements 120 assigned to a certain section 140 are at least approximately the same.

[0156] In particular, for all focus elements 120 and / or for all pairs of adjacent focus elements 120, the distance component d of the distance d oriented parallel to the thickness direction 134 of the material 102 and / or perpendicular to the feed direction 126 z is different from zero. In particular, all adjacent focus elements 120 are spaced apart in the thickness direction 134 by a non-zero effective distance component d z apart.

[0157] In addition, the processing line 136 and / or each section 140 of the processing line 136 is assigned a specific angle of attack α and / or an angle-of-attack range, which is formed by the processing line 136 and / or each section 140 and the first outer side 130 of the workpiece 104.

[0158] When the angle of attack is between 1° and 89°, each adjacent focus element 120 respectively has another non-zero distance component d of the distance d x which is perpendicular to the feed direction 126 and perpendicular to the distance component d z oriented.

[0159] The distance component d z and the distance component d x are respectively located in a plane oriented perpendicular to the feed direction 126.

[0160] In the illustrated embodiment, the angle of attack α of the first section 140a and the third section 140c is numerically 45°, and the angle of attack α of the second section 140b is 90°.

[0161] It can be set that all the focus elements 120 formed for laser processing of the workpiece 104 are all located in a plane oriented perpendicular to the feed direction 126. For example, in Figure 2 the situation shown, for all focus elements 120, at a certain time point, the location position z0 relative to the z direction is the same.

[0162] However, in principle, it is also possible that at least a part of the formed focus elements are spaced apart and positioned parallel to the feed direction 126. Herein, for example, in Figure 2In the situation shown, there is a focus element 120, the location position z0 of which relative to the z-direction is different. In this case, the machining line 136 or the arrangement of the focus element 120 along the machining line 136 is defined by observing the focus element 120 in a projection plane oriented perpendicular to the feed direction 126.

[0163] In particular, at a defined point in time, all focus elements 120 formed for laser machining of the workpiece 104 are present simultaneously, and in particular are not formed successively in time.

[0164] By loading and / or introducing the focus element 120 into the material 102, local material modification portions 138 are respectively formed, which are arranged in the material 102 at the corresponding location positions x0, y0, z0 of the corresponding focus element 120 ( Figure 3 ). By appropriately selecting machining parameters, such as the corresponding distance d between the focus elements 120, their corresponding intensity I, the feed speed oriented in the feed direction 126, and the laser parameters of the input laser beam 108, the material modification portions 138 can be formed, for example, as type III modifications, and type III modifications are accompanied by the spontaneous formation of cracks 137 in the material 102 of the workpiece 104. In particular, cracks 137 are formed between adjacent material modification portions 138.

[0165] As an alternative thereto, it is also possible that, by appropriately selecting machining parameters, the material modification portions 138 are formed as type I modifications and / or type II modifications, and type I modifications and / or type II modifications are accompanied by heat accumulation in the material 102 and / or a change in the refractive index of the material 102. The formation of the material modification portions 138 as type I and / or type II modifications is associated with heat accumulation in the material 102 of the workpiece 104. In particular, in order to form these material modification portions 138, the corresponding distance d between the focus elements 120 is selected to be so small that this heat accumulation occurs when the material 102 is loaded with the focus element 120.

[0166] Figure 4a The simulated intensity distribution of a plurality of focus elements 120 is shown, wherein the distance d between these focus elements 120 is approximately 17.5 μm. In the shown grayscale image, the brighter areas represent higher intensities.

[0167] Figure 4b The simulated intensity distribution of a plurality of focus elements 120 is shown, wherein the distance d is approximately 8.0 μm.

[0168] It is arranged that, after the material modification portions 138 are successfully formed, the material 102 is loaded with the heating laser beam 142 in order to break up the material (see Figure 3 and Figure 6)。To provide the heating laser beam 142, the laser system 100 includes an additional laser beam source 144, which is configured, for example, as a CO2 laser or includes a CO2 laser.

[0169] For example, the wavelength of the heating laser beam 142 is between 9 μm and 11 μm. For example, the wavelength is 10.6 μm. Here, the power of the heating laser beam 142 is, for example, between 20 W and 35 W.

[0170] In particular, the heating laser beam 142 is a pulsed laser beam, where the frequency is between 10 kHz and 15 kHz, for example 12.5 kHz. In principle, it is also possible that the heating laser beam 142 is a continuous wave laser beam (cw-Laserstrahl).

[0171] The heating laser beam 142 is to be understood as a beam cluster including a plurality of beams. The heating laser beam 142 has a transverse beam cross-section 146 and / or a transverse beam extension, and the heating laser beam impinges on the first outer side 130 of the workpiece 104 with this transverse beam cross-section and / or transverse beam extension.

[0172] In particular, the heating laser beam 142 impinging on the first outer side 130 is divergent or collimated.

[0173] The longitudinal central axis 148 of the heating laser beam 142 is preferably oriented perpendicular to the first outer side 130. The longitudinal central axis 148 is to be understood in particular as the beam axis and / or the symmetry axis of the heating laser beam in the beam propagation direction. The longitudinal central axis 148 is oriented parallel to the beam propagation direction of the heating laser beam 142.

[0174] The diameter d1 of the heating laser beam 142 (schematically shown in Figure 6 is preferably between 2 mm and 4 mm. For example, the diameter d1 is 2.7 mm. In this regard, the diameter d1 of the heating laser beam 142 is defined using the second moment method according to ISO 11146-3.

[0175] The longitudinal central axis 148 of the heating laser beam 142 has a location offset Δd with respect to the material modification 138a closest to the first outer side 130, and this location offset is oriented parallel to the first outer side 130 and / or perpendicular to the feed direction 126. In the Figure 3 and Figure 6 example shown, the location offset Δd is oriented parallel to the x direction.

[0176] The laser machining of the workpiece 104 using the laser system 100 works as follows:

[0177] To perform laser machining, the material 102 of the workpiece 104 is loaded with the focus element 120, and the focus element 120 is moved relative to the workpiece 104 in the feed direction 126 through the material 102 of the workpiece.

[0178] Here, the material 102 is a material that is transparent to the wavelength of the laser beam that respectively forms the focus element 120, such as a glass material. In the example shown, the focus element 120 is formed by beam shaping of the input laser beam 108.

[0179] By loading the material 102 with the focus element 120, a material modification portion 138 is formed in the material 102, and the material modification portion is arranged along the machining line 136 in a cross section oriented perpendicular to the feed direction 126 ( Figure 5a ). For example, as Figure 5a shown, the material modification portion 138 is formed continuously over the entire thickness D of the material 102.

[0180] By the relative movement of the focus element 120 relative to the material 102 along a pre-given feed line 150, a machining surface 152 corresponding to the machining line 136 is formed, and the material modification portion 138 is arranged on this machining surface. Thus, a surface-like structure and / or arrangement of the material modification portions 138 along the machining surface 152 is obtained.

[0181] The feed line 150 is defined by the movement of the focus element 120a closest to the first outer side surface 130 relative to the material 102 (see Figure 2 ), and corresponds to the trajectory of this focus element 120a relative to the material 102. The movement of the focus element 120 along the feed line 150 should be understood as each focus element 120 moving along a trajectory parallel to the feed line 150 (and the focus element 120a moving along the same trajectory as the feed line 150). Therefore, the feed line 150 should be understood as a reference line and / or reference trajectory for all focus elements 120.

[0182] The feed direction 126 is always oriented tangentially to the feed line 150. The feed direction does not have to be constant, for example, as Figure 5a shown, but can in principle vary. Therefore, the feed line 150 can in principle have straight and curved sections. In the case of a curved section, during laser machining, the feed direction 126 changes, and the machining line 136 is rotated so that it is always in a plane oriented perpendicular to the feed direction 126. This can be achieved, for example, by rotating the beam splitting element 106 accordingly or by relative rotation of the components of the laser system 100 relative to the workpiece 104.

[0183] The distance between adjacent material modification portions 138 in the feed direction 126 can be defined, for example, by adjusting the pulse duration of the input laser beam 108 and / or by adjusting the feed speed.

[0184] In particular, the material modification part 138 formed along the machining surface 152 causes a reduction in the strength of the material 102. As a result, after the material modification part 136 is formed, the material 102 can be divided into two different workpiece sections 154a, 154b at the machining surface 152( Figure 5b ).

[0185] In the example shown, the workpiece section 154b is a finished product section with a breaking surface 156 having a shape corresponding to the shape of the machining line 136. In this case, the workpiece section 154a is a residual workpiece section and / or a waste section.

[0186] After the material modification part 138 arranged on the machining surface 152 is formed, the workpiece 104 is broken by means of the heating laser beam 142. For this purpose, the heating laser beam 142 is directed onto the first outer side 130 and moves relative to the workpiece 104 along the heating laser beam feed line 158, which is oriented parallel to the feed line 150 along which the focus element 120 previously moved relative to the workpiece 104. The heating laser beam feed line 158 extends at a location offset Δd spaced apart from the feed line 150.

[0187] The relative movement of the heating laser beam 142 relative to the material 102 of the workpiece 104 is realized, for example, by means of a feed device 127, which can be correspondingly configured for this purpose.

[0188] The heating laser beam feed line 158 corresponds to the position of the longitudinal central axis 148 of the heating laser beam 142 on the first upper side 130. Therefore, the heating laser beam feed line 158 corresponds to the trajectory of the longitudinal central axis 148 of the heating laser beam 142 moving on the first upper side 130.

[0189] The feed speed at which the heating laser beam 142 moves along the heating laser beam feed line 158 is, for example, 2.4 m / min.

[0190] It is provided that the machining surface 152 protrudes and / or arches outwards relative to a partial area 162 of the workpiece 104. In Figure 5a and Figure 5b the example shown, the partial area 162 corresponds to the workpiece section 154b formed after breaking. Due to the arching of the machining surface 152, after breaking, an outward bulge 164 and / or protrusion is obtained on the workpiece section 154.

[0191] Therefore, the machining surface 152 (and the resulting breaking surface 156) is assigned a main direction 160 (see Figure 5a and Figure 6), which points in the direction of the arching and / or bulging 164 of the machining surface 152 from the inside of the workpiece 104. The main direction 160 is oriented perpendicular to the plane 166, which is parallel to the thickness direction 134 and extends parallel to the feed line 150.

[0192] The main direction 160 is derived from the direction of the distance d0 oriented parallel to the normal of the plane 166 between the material modification part 138a closest to the first outer side 130 and the material modification part 138b having the maximum distance from the material modification part 138a parallel to the normal of the plane 166 (see Figure 6 ). Here, the material modification part 138 is observed in a cross-sectional plane oriented perpendicular to the feed direction 126 or perpendicular to the feed line 150.

[0193] Therefore, the main direction 160 corresponds to the direction component of the displacement vector from the material modification part 138a to the material modification part 138b that is oriented parallel to the normal of the plane 166.

[0194] The distance d0 between the material modification part 138a and the material modification part 138b corresponds to the extension length of the machining line 136 and / or the machining surface 152 and / or the parting surface 156 in the main direction 160.

[0195] In particular, the material modification part 138a closest to the first outer side 130 can be adjacent to the first outer side 130 and / or can penetrate the first outer side 130.

[0196] The direction of the location offset Δd is opposite to and / or anti-parallel to the direction of the main direction 160.

[0197] By thermally loading the material 102 with the heating laser beam 142, the material 102 is parted along the machining surface 152, thereby generating, for example, Figure 5b the workpiece segments 154a and 154b shown in

[0198] In Figure 6 the shown embodiment, the machining line 136 is formed in an arc shape, and in particular a circular arc shape, such that the machining surface 152 or the parting surface 156 that arches outwards correspondingly in an arc shape is generated.

[0199] In the embodiment according to Figure 6 the distance d0 between the material modification part 138a and the material modification part 138b is, for example, 140 μm. In the case where the diameter d1 of the heating laser beam is 2.7 mm, the location offset Δd is, for example, 1000 μm.

[0200] The material 102 of the workpiece 104 is, for example, aluminosilicate glass. For example, in order to form the material modification part 138 into a type III modification part, the laser beam forming the focal element 120 has a wavelength of 1030 nm and a pulse duration of 3 ps. In addition, the numerical aperture assigned to the focusing optical device 118 is 0.4, and the pulse energy assigned to a single focal element 120 is 50 nJ to 200 nJ.

[0201] List of reference numerals

[0202] α angle of attack

[0203] d distance

[0204] d x Effective distance component

[0205] d z Effective distance component

[0206] d0 distance / extension length

[0207] d1 diameter

[0208] Δd location offset

[0209] D thickness

[0210] I intensity

[0211] x0 position in the x direction

[0212] y0 position in the y direction

[0213] z0 position in the z direction

[0214] 100 laser system

[0215] 102 material

[0216] 104 workpiece

[0217] 106 beam splitter element

[0218] 108 input laser beam

[0219] 110 laser beam source

[0220] 112 beam cross section

[0221] 114 wavefront

[0222] 116 sub-beam

[0223] 116a sub-beam

[0224] 116b sub-beam

[0225] 118 focusing optical device

[0226] 119 Processing laser beam

[0227] 120 Focus element

[0228] 120a Focus element

[0229] 121 Focus distribution

[0230] 122 Beam shaping device

[0231] 124 Beam propagation direction

[0232] 126 Feed direction

[0233] 127 Feeding device

[0234] 130 First outer side

[0235] 132 Second outer side

[0236] 134 Thickness direction

[0237] 136 Processing line

[0238] 137 Crack

[0239] 138 Material modification part

[0240] 138a Material modification part

[0241] 138b Material modification part

[0242] 140 Section

[0243] 140a First section

[0244] 140b Second section

[0245] 140c Third section

[0246] 142 Heating laser beam

[0247] 144 Additional laser beam source

[0248] 146 Beam cross-section

[0249] 148 Longitudinal central axis

[0250] 150 Feed line

[0251] 152 Processing surface

[0252] 154a Workpiece section

[0253] 154b Workpiece section

[0254] 156 Split cross-section

[0255] 158 Heating laser beam feed line

[0256] 160 Main direction

[0257] 162 Partial area

[0258] 164 Protrusion

[0259] 166 Plane

Claims

1. A method for severing a workpiece (104), wherein, - a pulsed machining laser beam (119) is provided, which forms a plurality of focus elements (120), wherein the workpiece (104) comprises a material (102) that is transparent to the machining laser beam (119), - the focus elements (120) are introduced into the material (102) of the workpiece (104) and moved relative to the material (102) parallel to a pre-given feed line (150), wherein, by the relative movement of the focus elements (120) introduced into the material (102), a material modification portion (138) arranged along a machining surface (152) is formed in the material (102), and wherein the machining surface (152) protrudes in a main direction (160) relative to a partial region (162) of the workpiece (104), and - the material (102) is loaded with a heating laser beam (142), wherein the material (102) of the workpiece (104) is opaque to the heating laser beam (142), wherein, - the heating laser beam (142) is moved relative to the material (102) along a heating laser beam feed line (158), whereby the material (102) is severed along the machining surface (152), wherein, - the heating laser beam feed line (158) extends parallel to the feed line (150) and is spaced apart from the feed line (150) by a site offset (Δd) that is anti-parallel to the main direction (160), and wherein the site offset (Δd) is at least 10% and at most 50% of the diameter (d1) of the heating laser beam.

2. The method according to claim 1, wherein The site offset (Δd) is at least 15% and in particular at least 20% and in particular at least 25% of the diameter (d1) of the heating laser beam.

3. The method according to any one of the preceding claims, characterized in that, The machining laser beam (119) and / or the heating laser beam (142) is / are coupled into the material (102) of the workpiece (104) through a first outer side (130) of the workpiece (104), wherein the thickness direction (134) of the workpiece (104) is oriented transversely and in particular perpendicularly to the first outer side (130).

4. The method according to any one of the preceding claims, characterized in that, The machining surface (152) is loaded with the heating laser beam (142) relative to the partial region (162) that protrudes in the main direction (160) therefrom, and / or, the heating laser beam feed line (158) extends in the partial region (162) where the machining surface (152) protrudes in the main direction (160) therefrom.

5. The method according to any one of the preceding claims, characterized in that, The main direction (160) is oriented perpendicular to a plane (166) that is parallel to the feed line (150) and extends parallel to the thickness direction (134) of the workpiece (104) to be severed.

6. The method according to any one of the preceding claims, characterized in that, The machining surface (152) extends continuously between a first outer side (130) and a second outer side (132) of the workpiece (104), and the second outer side is spaced apart from the first outer side (130) in the thickness direction (134).

7. The method according to any one of the preceding claims, characterized in that, The heating laser beam (142) has a diameter (d1) of at least 0.5 mm and at most 5 mm, and in particular at least 2 mm and at most 4 mm.

8. The method according to any one of the preceding claims, characterized in that, The machining laser beam (119) has a wavelength of at least 300 nm and at most 1500 nm, and / or the machining laser beam (119) has ultrashort laser pulses.

9. The method according to any one of the preceding claims, characterized in that, The heating laser beam (142) has a wavelength of at least 9 μm and at most 11 μm.

10. The method according to any one of the preceding claims, characterized in that, The workpiece (104) to be severed has a thickness (D) between 10 μm and 10 mm, preferably between 100 μm and 1 mm, and particularly preferably between 450 μm and 650 μm.

11. The method according to any one of the preceding claims, characterized in that The extension length (d0) of the machining surface oriented parallel to the main direction (160) has at least 5% and at most 70%, and preferably at least 15% and at most 35% of the thickness (D) of the workpiece (104) to be severed.

12. The method according to any one of the preceding claims, characterized in that, When observed in a cross-section oriented perpendicular to the feed line (150) and / or in a projection oriented perpendicular to the feed line (150), the focal element (120) is arranged along a pre-given machining line (136), and the pre-given machining line defines the cross-sectional shape of the machining surface (152) and / or defines the cross-sectional shape of the severed surface (156) formed by severing the material (102) along the machining surface (136).

13. The method according to any one of the preceding claims, characterized in that, The focal element (120) is formed by splitting an input laser beam (108) into a plurality of sub-beams (116) by means of a beam splitting element (106) and focusing the sub-beams (116) coupled out from the beam splitting element (106), and it is characterized in particular that the splitting of the input laser beam (108) by means of the beam splitting element (106) is carried out by or includes imposing a phase on the beam cross-section (112) of the input laser beam (108).

14. The method according to any one of the preceding claims, characterized in that, By loading the material (102) of the workpiece (104) with the focal element (120), a material modification (138) is formed in the material (102), wherein the material modification (138) is accompanied by crack formation in the material (102), and / or wherein the material modification (138) is a type III material modification.

15. A laser system for severing a workpiece (104), comprising: - a laser beam source (110), a beam splitting element (106) and a focusing optical device (118), which together are configured to provide a machining laser beam (119) that forms a plurality of focal elements (120) for introduction into the material (102) of the workpiece (104), - A feed device (127) for performing a relative movement of the focus element (120) relative to the material (102) of the workpiece (104) parallel to a predefined feed line (150) in order to form a material modification portion (138) arranged along a machining surface (152) in the material (102), wherein it is provided that the machining surface (152) projects in a main direction (160) with respect to a partial region (162) of the workpiece (104). - A further laser beam source (144) for providing a heating laser beam (142), wherein the feed device (127) is configured to move the heating laser beam (142) relative to the material (102) along a heating laser beam feed line (158) in order to sever the material (102) along the machining surface (152), wherein - the heating laser beam feed line (158) extends parallel to the feed line (150) and is spaced apart from the feed line (150) by a location offset (Δd) that is anti-parallel to the main direction (160), and wherein the location offset (Δd) is at least 10% and at most 50% of the diameter (d1) of the heating laser beam.

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