Method and device for laser machining workpieces

Abstract

The invention relates to a method for laser processing a workpiece (104) having a transparent material (102), in which an input laser beam (108) is split into a plurality of sub-beams (116) by means of a beam splitting element (106), the sub-beams (116) decoupled from the beam splitting element (106) are focused, in which a plurality of focus elements (120) are formed by focusing the sub-beams (116), the material (102) of the workpiece (104) is loaded with a focus element (120) for laser machining and the focus element (120) is moved relative to the material (102) in a feed direction (126), characterized in that a partial quantity (120a) of the formed focus element is arranged in a first plane (141a) and a partial quantity (120b) of the formed focus element is arranged in at least one further plane (141b), the first plane (141a) and the at least one further plane (141b) are spaced apart parallel to the feed direction (126), and wherein the first plane (141a) and the at least one further plane (141b) are oriented perpendicular to the feed direction (126).

Description

Technical Field

[0001] The present invention relates to a method for laser processing a workpiece having a transparent material, wherein an input laser beam is split into a plurality of sub-beams by means of a beam splitting element, and the sub-beams coupled out from the beam splitting element are focused, wherein a plurality of focal elements are formed by focusing the sub-beams, the material of the workpiece is loaded with the focal elements for laser processing, and the focal elements are moved relative to the material in a feed direction.

[0002] Furthermore, the present invention relates to an apparatus for laser processing a workpiece having a transparent material, comprising: a beam splitting element for splitting an input laser beam into a plurality of sub-beams; a focusing optical device for focusing the sub-beams coupled out from the beam splitting element, wherein a plurality of focal elements for laser processing the workpiece are formed by focusing the sub-beams; and a feed device for performing a relative movement of the focal elements relative to the material of the workpiece in a feed direction. Background Art

[0003] WO 2022 / 167254 A1 and WO 2022 / 167257 A1 each disclose a method and an apparatus for laser processing a transparent workpiece, wherein the workpiece is loaded with a plurality of focal elements for laser processing.

[0004] DE 10 2014 116 958 A1 discloses a diffractive optical beam shaping element for imposing a phase distribution on a laser beam by means of a phase mask, the laser beam being provided for laser processing a material that is substantially transparent to the laser beam, the phase mask being formed for imposing a plurality of phase distributions for beam shaping on the laser beam incident on the phase mask, wherein at least one of the plurality of phase distributions for beam shaping is assigned a virtual optical image, which can be imaged in at least one elongated focusing region to form a modified portion in the material to be processed.

[0005] A method for severing / splitting a transparent material using an elongated focusing region of a laser beam is known from EP 3 597 353 A1.

[0006] A method for severing a transparent material and in particular for beveling a transparent material is known from JP 2020 004 889A, wherein a spatial light modulator is used to generate a plurality of focal points for laser processing the material.

[0007] A method for forming a beveled edge region on a transparent material using a laser beam is known from US2020 / 0147729 A1 and US2020 / 0361037 A1, respectively.

[0008] A method for cutting a transparent material using a plurality of parallel non-diffracting laser beams is known from WO 2016 / 089799 A1. SUMMARY OF THE INVENTION

[0009] OBJECT OF THE INVENTION

[0010] It is an object of the present invention to provide a method and an apparatus as described above, by means of which a material modification can be formed in the material of a workpiece, which material modification enables the material to be cut with improved quality and in particular enables the roughness at the cut surface to be reduced.

[0011] In the method mentioned at the beginning, this object is achieved according to the invention in such a way that a partial amount of the formed focal elements is arranged in a first plane and a partial amount of the formed focal elements is arranged in at least one further plane, wherein the first plane and the at least one further plane are spaced apart parallel to the feed direction, and wherein the first plane and the at least one further plane are oriented perpendicular to the feed direction.

[0012] During laser machining of a workpiece by means of a method according to the invention, a material modification is generated in the material of the workpiece, which material modification in particular enables the material to be cut.

[0013] By arranging the focal elements in both the first plane and the at least one further plane, the effective distance of the focal elements oriented perpendicular to the feed direction can be reduced. This enables adjacent material modifications to be generated in the material of the workpiece with a particularly small distance, which in turn increases the density of the material modifications formed in the material. This improves the cutability of the material. In addition, the quality of the cut surface generated during material cutting can be improved, wherein the cut surface can in particular be implemented with reduced roughness and / or increased smoothness. Thereby, after successful cutting, a higher edge stability of the workpiece material at the cut surface is obtained.

[0014] If the actual distance between adjacent focal elements becomes too small, an undesired interference effect may thereby occur between the adjacent focal elements, which may have consequences such as a beat frequency effect with respect to the intensity of the focal elements. This may make it difficult to control the formation of the material modification and in particular make it difficult to form identical material modifications. In the solution according to the invention, the focal elements for forming the material modification are arranged "staggered" in the feed direction, whereby a significant reduction in the effective distance is caused when the actual distance between the focal elements is large enough.

[0015] The distance between the focal elements or the actual distance is to be understood as the actual distance in three-dimensional space between these focal elements. The effective distance between the focal elements is the distance between the perpendicular projections of the focal elements in a projection plane oriented perpendicular to the feed direction.

[0016] The spatial position and / or arrangement of a particular focal element is to be understood in particular as the spatial position and / or arrangement of its center point and / or center of gravity within the material. In particular, the distance and the effective distance are with respect to the corresponding center points of the focal elements in the material, i.e., the center point distance is involved.

[0017] By the relative movement of the focal elements arranged in the first plane and the at least one further plane relative to the material in the feed direction, material modifications spaced apart by the effective distance are produced at least in a section of the material.

[0018] Using the method according to the invention, it is possible in particular to form material modifications such that adjacent material modifications in the material overlap. Thereby, a crack connection between adjacent material modifications is obtained, which enables the material to be separated particularly well by etching or applying heat.

[0019] By loading the material of the workpiece with the focal elements at a specific point in time, material modifications are formed, which are arranged in the material at the position where the focal elements are located in the material at this point in time.

[0020] In particular, all focal elements assigned to the first plane and / or the at least one further plane are present simultaneously.

[0021] For example, it is possible to provide two or more planes oriented perpendicular to the feed direction, in which partial amounts of the formed focal elements are respectively arranged. The provided planes are respectively oriented parallel to each other and / or spaced apart from each other in the feed direction.

[0022] In particular, it can be provided that the distance between the first plane and the at least one further plane can be at least 2 μm and / or at most 200 μm. For example, this distance is approximately 10 μm.

[0023] In particular, it can be provided that the formed focal elements are positioned such that when the focal elements are observed in a projection plane oriented perpendicular to the feed direction, at least one partial amount of "the focal elements assigned to the first plane and the focal elements assigned to the at least one further plane" is arranged at different spatial positions in the projection plane. This enables the effective distance between adjacent focal elements to be reduced, such that the distance between the formed adjacent material modifications is correspondingly reduced.

[0024] In particular, it can be arranged that the formed focus elements are positioned such that when the focus elements are observed in a projection plane oriented perpendicular to the feed direction, at least some of the focus elements assigned to the first projection plane and the focus elements assigned to the at least one further projection plane are positioned along a processing line in the projection plane, wherein, by the relative movement of the focus elements relative to the material in the feed direction, material modifications arranged along the processing line are produced in the material. In particular, the edge geometry and / or cross-sectional geometry of the parting plane caused by the material separation at the material modification can be defined by means of the processing line.

[0025] For example, the total length of the at least one processing line is 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. Thus, workpieces having a thickness within this range can be machined and in particular parted.

[0026] For example, the material of the workpiece has a thickness between 10 μm and 10,000 μm, and preferably between 100 μm and 1,000 μm, for example approximately 500 μm.

[0027] In particular, it can be arranged that the processing line is formed spatially continuously over the thickness of the material of the workpiece and / or over the thickness of the workpiece section to be separated from the workpiece.

[0028] The processing line does not have to be constructed spatially continuously, but can have different, spatially separated sections. In particular, the processing line can have interruptions at which no focus elements are arranged.

[0029] In particular, by the relative movement of the focus elements in the material, material modifications are produced along a processing surface corresponding to the processing line. Then, in particular when observed in a cross-section of the processing surface oriented perpendicular to the feed direction, the material modifications are arranged along the processing line. After the workpiece has been parted at the material modifications arranged along the processing surface, the shape and / or cross-sectional shape of the parting plane formed in the case of the parting then corresponds in particular to the shape and / or cross-sectional shape of the (previous) processing surface.

[0030] It can be advantageous if the adjacent focus elements arranged along the processing line have an effective distance of at least 2 μm and / or at most 200 μm in the projection plane. Thereby, a parting plane with particularly high quality and / or reduced roughness can be implemented.

[0031] The focus elements arranged along the processing line and / or observed in the projection plane are to be understood as meaning the focus elements assigned to the first plane and the at least one further plane.

[0032] In particular, the effective distance of the focal elements along the processing line at least approximately corresponds to the distance of the following material modification sections, which are formed on the processing surface corresponding to the processing line and are located in a section of the processing surface oriented perpendicular to the feed direction.

[0033] In particular, it can be arranged that the effective distance of adjacent focal elements arranged along the processing line in the projection plane and / or the intensity of the focal elements are selected such that by loading the material with the focal elements and the relative movement of the focal elements relative to the material in the feed direction, material modification sections are generated in the material, which enable the material to be severed.

[0034] In particular, it can be arranged that at least some of the adjacent focal elements arranged along the processing line are spaced apart from each other in the projection plane by at least approximately the same effective distance.

[0035] It can be advantageous that at least some of the adjacent focal elements arranged along the processing line are spaced apart by an effective distance, where this effective distance has a non-zero effective distance component oriented parallel to the thickness direction of the workpiece and / or has another non-zero effective distance component oriented perpendicular to the thickness direction of the workpiece. Thereby, for example, a vertical cut can be performed on the workpiece, or the workpiece can be chamfered at a specific angle.

[0036] The thickness direction of the workpiece is to be understood in particular as the direction oriented transversely and in particular perpendicular to the outer side / surface of the workpiece, through which the focal element and / or the laser beam used to form the focal element is coupled into the material.

[0037] The thickness direction is in particular oriented transversely or perpendicular to the beam propagation direction of the laser beam forming the focal element.

[0038] In particular, it can be arranged that at least some of the adjacent focal elements arranged along the processing line are spaced apart by an effective distance, where this effective distance has a non-zero effective distance component oriented parallel to the beam propagation direction of the laser beam forming the focal element, and / or at least some of the adjacent focal elements arranged along the processing line are spaced apart by an effective distance, where this effective distance has a non-zero effective distance component oriented perpendicular to the beam propagation direction of the laser beam forming the focal element.

[0039] For the same reason, it can be advantageous that the angle of attack between the processing line and the outer side of the workpiece is at least sectionally at least 1° and / or at most 90° and in particular at most 89°, through which the focal element is coupled into the material of the workpiece for laser processing. Depending on the choice of the angle of attack, for example, a vertical cut can be performed on the workpiece, or the workpiece can be chamfered at a specific angle.

[0040] The processing line has a specific angle of attack or range of angles of attack at least in sections, and in particular it is to be understood that the processing line has at least one section which has this angle of attack or range of angles of attack.

[0041] 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°.

[0042] In particular, it can be arranged that the angle of attack of the processing line is at least in sections constant, and / or the processing line has a plurality of sections which have different angles of attack.

[0043] In particular, it can be arranged that the processing line is at least in sections straight, and / or the processing line is at least in sections curved.

[0044] For example, by implementing the processing line as a curve, a rounded section can be separated from the workpiece. For example, a rounded edge can thus be created.

[0045] When the processing line is implemented as a curve, the processing line is assigned, for example, a specific range of angles of attack, the specific range of angles of attack which the processing line has with respect to the outer side of the workpiece.

[0046] It can be advantageous if the formed focus elements are positioned such that when the focus elements are observed in a projection plane oriented perpendicular to the feed direction, a gap is respectively formed between adjacent focus elements assigned to the first plane, and there are focus elements assigned to the at least one further plane which are arranged in the gap. This makes it possible to reduce the effective distance between adjacent focus elements and / or increase the density of the material modification parts formed in the material.

[0047] In particular, it can be arranged that the distance between adjacent focus elements assigned to the first plane is at least 3 μm and / or at most 70 μm, and in particular at least 5 μm and / or at most 10 μm.

[0048] In particular, it can be arranged that the distance between adjacent focus elements assigned to the at least one further plane is at least 3 μm and / or at most 70 μm, and in particular at least 5 μm and / or at most 10 μm.

[0049] In particular, it can be arranged that the splitting of the input laser beam by means of the beam splitting element is carried out by or includes the phase addition to the beam cross section of the input laser beam. Thus, the focus elements can for example be formed as copies of one another. In particular, the focus elements can thus be introduced into the material of the workpiece at different positions and / or with different spacings in a technically simple manner.

[0050] It can be set that the splitting of the input laser beam is achieved only by imposing a phase on the beam cross-section of the input laser beam.

[0051] In particular, the phase imposition occurs 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.

[0052] Alternatively or additionally, it can be set that the splitting of the input laser beam by means of a beam splitting element is carried out by polarization beam splitting or includes polarization beam splitting. Then, the adjacent focal elements can each be formed, for example, with different polarization states. This makes it possible to prevent interference between adjacent focal elements, which means that they can be arranged at a particularly small distance from each other.

[0053] In principle, the splitting of the input laser beam can be carried out by means of both phase imposition and polarization beam splitting.

[0054] In particular, the input laser beam and / or the laser beam forming the focal element is a pulsed laser beam and especially an ultrashort pulsed laser beam. Thereby, by loading the material with the focal elements, in particular laser pulses and especially ultrashort laser pulses are introduced into the material.

[0055] The material modifications introduced into the transparent material by ultrashort laser pulses are subdivided into three different classes, see "Ultrafast Processes for Bulk Modification of Transparent Materials" by K. Itoh et al., MRS Bulletin, Vol. 31, p. 620 (2006): Type I is an isotropic refractive index change; Type II is a birefringent refractive index change; and Type III is voids or cavities. The type of material modification produced by a specific focal element depends on the laser parameters of the laser beam forming the corresponding focal element, such as the pulse duration, wavelength, pulse energy, and repetition rate of the laser beam. In addition, the type of modification depends on the properties of the material, such as especially the electronic structure and thermal expansion coefficient of the material, and on the numerical aperture (NA) used when focusing the laser beam to the corresponding focal element.

[0056] The refractive index change is attributed to the locally confined melting by the laser pulse and the 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 mastered by the focal element melts and then cools rapidly, the fused silica has a higher refractive index in the region of the material modification than in the unmodified region.

[0057] The refractive index change of type-II birefringence can occur, for example, due to the interference between an ultrashort laser pulse and the electric field of a plasma generated by the laser pulse. This interference results in a periodic modulation of the electron plasma density, which leads to the birefringence properties of the transparent material during solidification, that is, a direction-dependent refractive index. For example, type-II modification is also accompanied by the formation of so-called nanogratings.

[0058] In particular, voids (cavities) of type-III modification can be generated using high laser pulse energies. Here, the formation of the voids is attributed to the explosive expansion of the 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 material mass, the microexplosion leaves a less dense or hollow core (void), or rather, minute defects in the submicron or atomic range, which are surrounded by a cladding of compressed material. The compression at the shock wave front of the microexplosion generates stress in the transparent material, which regularly leads to the formation of spontaneous cracks or promotes crack formation.

[0059] Therefore, when it comes to introducing type-III modification, there will in any case be a less dense or hollow core or rather a defect. Exemplarily, in sapphire in the case of type-III modification, less dense regions rather than voids are generated by microexplosions.

[0060] In particular, the formation of voids can also be accompanied by type-I modification and type-II modification. Exemplarily, type-I modification and type-II modification can 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 modification and type-II modification. Therefore, it is unlikely to find a "pure" type-III modification.

[0061] It can be advantageous to generate a material modification in the material by loading the material of the workpiece with a focal element, 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 material can be segmented by means of these material modifications.

[0062] It can be advantageous to form a material modification in the material by loading the material of the workpiece with a focal element, where the material modification is accompanied by a change in the refractive index of the material, and / or the material modification is a type-I material modification and / or a type-II material modification. In particular, the material can be segmented by means of these material modifications.

[0063] In particular, it can be arranged that after the laser machining is completed, the material of the workpiece is segmentable or segmented, where, in particular, it can be arranged that at the machining surface where the material modification is formed by means of laser machining, the material is segmentable or segmented.

[0064] In particular, it can be set such that, by implementing thermal loading and / or mechanical stress and / or by etching with the aid of at least one wet chemical solution, the material of the workpiece is separable or is separated. For example, the etching is carried out in an ultrasonically assisted etching bath. For example, the thermal loading can be achieved by means of a CO2 laser.

[0065] According to the invention, in the device mentioned at the beginning, it is provided that the beam splitting element and the focusing optics are configured to arrange the focal elements in such a way that a partial amount of the formed focal elements is arranged in a first plane, and a partial amount of the formed focal elements is arranged in at least one further plane, the first plane and the at least one further plane being spaced apart parallel to the feed direction, and wherein the first plane and the at least one further plane are oriented perpendicular to the feed direction.

[0066] In particular, the device according to the invention has one or more further features and / or advantages of the method according to the invention. Advantageous embodiments of the device according to the invention have been illustrated in connection with the method according to the invention.

[0067] In particular, the method according to the invention can be carried out by means of the device according to the invention, or the method according to the invention is carried out by means of the device according to the invention.

[0068] It can be advantageous if the beam splitting element is formed as a 3D beam splitting element or comprises a 3D beam splitting element. Then, it can be set that the splitting of the input laser beam is carried out by phase imposition on the beam cross-section of the input laser beam, in particular only by phase imposition on the beam cross-section of the input laser beam.

[0069] It can be advantageous if the beam splitting element is formed as a polarization beam splitting element or comprises a polarization beam splitting element.

[0070] For example, the beam splitting element comprises a plurality of components and / or functions. It can be set that the beam splitting element comprises both a 3D beam splitting element and a polarization beam splitting element.

[0071] In particular, the device comprises a laser beam source for providing an input laser beam, wherein the input laser beam is in particular a pulsed laser beam and / or an ultrashort pulsed laser beam.

[0072] In particular, a transparent material should be understood to mean a material that transmits at least 70%, and in particular at least 80%, and in particular at least 90% of the laser energy of the input laser beam and / or of the laser beam forming the focal element.

[0073] In particular, a focal element should be understood as a radiation region having a specific spatial extent and intensity distribution. To determine the spatial dimensions, such as the diameter of a specific focal element, only the intensity values of the intensity distribution above a specific intensity threshold are considered. Here, the intensity threshold is selected, for example, 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.

[0074] In particular, each specific focal element is assigned a spatially interacting region in which the focal element interacts with the material when the focal element is introduced into the material of the workpiece.

[0075] In particular, the focal element introduced into the material interacts with the material by non-linear absorption. In particular, a material modification is produced in the material by means of the focal element based on non-linear absorption.

[0076] In particular, it can be provided 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 specific focal element that interacts 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.

[0077] The maximum spatial extent of a specific focal element is to be understood in particular as the maximum spatial extent of the focal element in any spatial direction.

[0078] Specifically, the corresponding 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.

[0079] In particular, the focal element has a diffracted beam profile. In particular, the focal element is designed to be diffraction-limited. For example, a specific focal element has a Gaussian shape and / or a Gaussian intensity profile.

[0080] In particular, the input laser beam and / or the laser beam forming the focal element has a diffracted beam profile and / or a Gaussian beam profile.

[0081] For example, the wavelength of the input laser beam and / or the laser beam forming the focal element is at least 300 nm and / or at most 1500 nm. For example, the wavelength is 515 nm or 1030 nm.

[0082] In particular, the input laser beam and / or the laser beam forming the focus element has an average power of at least 1 W to 1 kW. For example, the laser beam comprises pulses having a pulse energy of at least 10 μJ and / or at most 50 mJ. It can be arranged that the laser beam comprises single pulses or pulse trains, where the pulse trains have 2 to 20 sub-pulses, and in particular, the time interval is approximately 20 ns.

[0083] The expression "at least a portion of the amount of the focus element" can represent a partial amount of the focus element or the total amount of the focus element, i.e., all the focus elements.

[0084] In particular, the expressions "at least approximately" or "approximately" are to be generally understood as having a deviation of at most 10%. Unless otherwise stated, the expressions "at least approximately" or "approximately" should be understood as particularly meaning that the actual value and / or distance and / or angle deviate from the ideal value and / or distance and / or angle by no more than 10%. Description of the Drawings

[0085] The following description of the preferred embodiments serves to explain the present invention in more detail in conjunction with the drawings.

[0086] In the drawings:

[0087] Figure 1 A schematic view of an embodiment of an apparatus for laser machining of a workpiece is shown;

[0088] Figure 2 A schematic cross-sectional view of a section of the workpiece material is shown, in which the material is loaded with a plurality of focus elements for laser machining;

[0089] Figure 3 A schematic cross-sectional view of a section of the workpiece is shown, in which a material modification part is generated by loading the workpiece with focus elements, and crack formation in the material accompanies the material modification part;

[0090] Figure 4 An arrangement of focus elements configured for laser machining of a workpiece is shown, in which the projection of the focus elements in a projection plane oriented perpendicular to the feed direction is shown;

[0091] Figure 5a An arrangement of focus elements configured for laser machining of a workpiece in a cross-section oriented parallel to the feed direction and the workpiece thickness direction is shown;

[0092] Figure 5b Shown in a cross-section oriented parallel to the feed direction and perpendicular to the thickness direction of the workpiece according to Figure 5a of the focus elements;

[0093] Figure 6is shown in a perspective view according to Figure 5a and Figure 5b focus elements;

[0094] Figure 7a shows a cross-sectional view of the simulated intensity distribution of a focus element for laser machining of a workpiece, wherein adjacent focus elements are each spaced apart by a distance of approximately 17.5 μm.

[0095] Figure 7b shows a cross-sectional view of the simulated intensity distribution of a focus element for laser machining of a workpiece, wherein adjacent focus elements are each spaced apart by a distance of approximately 8.0 μm.

[0096] Figure 8a shows a schematic perspective view of a workpiece on which material modification portions are formed, and these material modification portions extend along a machining line and / or a machining surface; and

[0097] Figure 8b shows a schematic perspective view of two workpiece segments, and these two workpiece segments are formed by dividing the workpiece according to

[0098] / or machining surface; Figure 8a is formed by dividing the workpiece;

[0099] Elements that are the same or have equivalent functions in all the figures are provided with the same reference numerals. Detailed Description

[0100] An embodiment of a device for laser machining of a workpiece is shown in Figure 1 and is designated as 100 in the figure. The device 100 can be used to generate local material modification portions in the material 102 of the workpiece 104 that cause the material to be weakened, such as defects in the sub-micron range or atomic range. At these material modification portions, the workpiece 104 can be divided, and a workpiece segment can be separated from the workpiece 104, for example.

[0101] In particular, the device 100 can be used to introduce the material modification portions into the material 102 at an angle of attack such that the edge region of the workpiece 104 can be chamfered or beveled by separating the workpiece segment from the workpiece 104.

[0102] The device includes a beam splitting element 106, and in particular, a collimated input laser beam 108 is coupled into the beam splitting element. The input laser beam 108 is provided by a laser beam source 110, for example. In particular, the input laser beam 108 is a pulsed laser beam and / or an ultrashort pulsed laser beam.

[0103] It can be set such that the laser beam source 110 includes a hollow core optical fiber (not shown), and the laser beam formed by the laser beam source exits from the hollow core optical fiber. Then, for example, the laser beam is collimated by a collimating optical device (not shown) of the laser beam source 110 to form a collimated input laser beam 108.

[0104] In particular, the input laser beam 108 should be understood to mean a beam cluster that includes a plurality of beams that extend parallel to each other in particular. The input laser beam 108 particularly has a transverse beam cross-section 112 and / or a transverse beam extension, and the input laser beam 108 irradiates the beam splitting element 106 with this transverse beam cross-section and / or transverse beam extension. The input laser beam 108 irradiating the beam splitting element 106 particularly has at least an approximately planar wavefront 114.

[0105] The input laser beam 108 is split by the beam splitting element 106 into a plurality of sub-beams 116 and / or sub-beam clusters. In Figure 1 the example shown, two different sub-beams 116a and 116b are schematically shown.

[0106] In particular, the beam splitting element 106 is configured as a far-field beam shaping element. The sub-beams 116 or sub-beam clusters coupled out from the beam splitting element 106 particularly have a divergent beam profile and / or propagate in the manner of a spherical wave.

[0107] To focus the sub-beams 116 coupled out from the beam splitting element 106, the device 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.

[0108] For example, the focusing optical device 118 has a focal length between 5 mm and 50 mm.

[0109] The beam splitting element 106 is particularly arranged at least approximately in the back focal plane of the focusing optical device 118.

[0110] In particular, the different sub-beams 116 irradiate the focusing optical device 118 with a position offset and / or an angular offset. These sub-beams 116 are focused by the focusing optical device 118 such that a plurality of focal elements 120 are formed, and the plurality of focal elements are each arranged at different spatial positions. In principle, adjacent focal elements can partially overlap in space.

[0111] For example, a respective focal element 120 is assigned one or more sub-beams 116 and / or sub-beam clusters. For example, the corresponding focal element 120 is formed by focusing one or more sub-beams 116 and / or sub-beam clusters.

[0112] The focal element 120 is in particular understood as a focused radiation region, such as a focal spot and / or a focus. In particular, the focal elements 120 each have a specific geometry and / or a specific intensity profile, where the geometry is understood, for example, as the spatial shape and / or the spatial extent of the focal element 120.

[0113] The geometry and / or the intensity profile of a defined focal element 120 is hereinafter referred to as the focal distribution 121 of the focal element 120. The focal distribution 121 is an attribute of the corresponding focal element 120 and describes the corresponding shape and / or intensity profile of the focal element. In particular, the plurality of formed focal elements 120 or all focal elements 120 have the same focal distribution.

[0114] The focal distribution of the formed focal elements 120 is defined by the input laser beam 108, and the splitting of the input laser beam by means of the beam splitting element 106 forms 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.

[0115] For example, if the input laser beam 108 is provided, for example, by means of a laser beam source 110, the input laser beam has a Gaussian beam profile. In this case, by focusing the input laser beam 108, the following focal elements will be formed, the focal distribution of which has a Gaussian shape and / or a Gaussian intensity profile.

[0116] Alternatively, it can be provided here, for example, that the input laser beam 108 is provided with a Bessel-like beam profile, such that by focusing the input laser beam 108, focal elements will be formed having a focal distribution having a Bessel-like shape and / or a Bessel-like intensity profile.

[0117] The sub-beams 116 and / or the sub-beam clusters formed by the splitting of the input laser beam 108 by means of the beam splitting element 106 are assigned the focal distribution of the input laser beam 108, such that by focusing the sub-beams 116, focal elements 120 are formed having this focal distribution and / or having a focal distribution based on this focal distribution.

[0118] In Figure 1 the example shown, the input laser beam 108 has a Gaussian beam profile, that is, the input laser beam 108 is assigned a focal distribution having a Gaussian shape and / or a Gaussian intensity profile. Here, the focal elements 120 each have, for example, a focal distribution 121 having this Gaussian shape and / or this Gaussian intensity profile or having a shape or intensity profile based on this Gaussian shape and / or this Gaussian intensity profile (see also Figure 5a andFigure 5b )。

[0119] For example, if the input laser beam 108 is assigned a Bessel-like beam profile, the focus elements 120 for the laser machining of the workpiece 104 each have a focus assignment 121, which has this Bessel-like beam profile or a beam profile based on this Bessel profile. Thus, the focus elements 120 can be formed, for example, each having a focus assignment that has an elongated shape and / or an elongated intensity profile.

[0120] It can be provided that the device 100 has a beam shaping device 122 for the beam shaping of the input laser beam 108 (as Figure 1 schematically shown). 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 between the laser beam source 110 and the beam splitting element 106.

[0121] The beam propagation direction is in particular understood to mean the main beam propagation direction and / or the average propagation direction of the laser beam and / or the beam cluster. The beam propagation direction in particular corresponds to the direction of the Poynting vector assigned to the laser beam or the beam cluster.

[0122] By means of the beam shaping device 122, the input laser beam 108 can be assigned a specific beam profile, which defines the focus assignment 121 of the focus elements 120.

[0123] The beam shaping device 122 can for example 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 an axicon element or includes an axicon element.

[0124] Here, the input laser beam 108 coupled into the beam splitting element 106 has a quasi-non-diffracting and / or Bessel-like beam profile. Correspondingly, the focus elements 120 then also have this quasi-non-diffracting and / or Bessel-like beam profile or a beam profile based on this beam profile.

[0125] Regarding the definition and implementation of quasi-non-diffracting and / or Bessel-like beams, reference is made to the following book: “Structured Light Fields: Applications in Optical Trapping, Manipulation and Organisation”, M. Springer Science&Business Media (2012), ISBN 978 - 3 - 642 - 29322 - 1, and also refer to the scientific publication "Bessel - like optical beams with arbitrary trajectories" by I Chremmos et al., Optics Letters, Vol. 37, No. 23, December 1, 2012, and "Generalized axicon - based generation of nondiffracting beams" by K.Chen et al., arXiv:1911.03103v1 [physics.optics], November 8, 2019.

[0126] By splitting the beam using the beam - splitting element 106, these focal elements 120 are in particular constructed to be congruent with each other respectively and / or are respectively constructed as copies of each other.

[0127] Each of the formed focal elements 120 is assigned a specific site position x0, y0, z0, and the corresponding focal element 120 is arranged at the site position relative to the material 102 of the workpiece 104 ( Figure 2 ). For example, the site position of the focal element 120 is understood to mean the position of its spatial center point and / or center of gravity.

[0128] In addition, in particular, each of the formed focal elements 120 is assigned a specific intensity I. The beam - splitting element 106 can be used to adjust the spatial positions x0, y0, z0 and in particular also the intensity I of the respective focal elements 120.

[0129] In particular, multiple or all of the focal elements 120 configured for laser processing of the workpiece 104 have the same intensity I. However, it is also possible that multiple of the formed focal elements 120 have different intensities I.

[0130] In particular, by means of the beam - splitting element 106, in three spatial directions and / or spatial dimensions (in Figure 1 the example shown, in the x, y, and z directions), the corresponding distance d and / or the corresponding spatial offset between adjacent focal elements 120 can be adjusted component - by - component.

[0131] The beam - splitting element 106 is preferably configured as a 3D beam - splitting element or includes a 3D beam - splitting element. Thus, the focal elements 120 can be formed, for example, such that they are identical to each other respectively and / or they respectively constitute copies of each other.

[0132] Regarding the technical implementation and properties of the beam splitter element 106 implemented as a 3D beam splitter element, reference is made to the scientific publication by D. Flamm et al., "Structured light for ultrafast laser micro-and nanoprocessing", arXiv:2012.10119v1 [physics.optics], December 18, 2020. Herein, the entire content thereof is expressly incorporated by reference.

[0133] In one embodiment of the beam splitter element 106, the beam splitter element 106 is implemented, for example, as a 3D beam splitter element. In this embodiment, in order to split the beam, a defined transverse phase distribution is imposed on the transverse beam cross-section 112 of the input laser beam 108. The transverse beam cross-section or transverse phase distribution is particularly understood to mean the beam cross-section or phase distribution in a plane oriented transversely to the beam propagation direction 124 of the input laser beam 108 and particularly perpendicular to the beam velocity propagation direction of this input laser beam.

[0134] The focal element 120 is 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.

[0135] In order to form the focal element 120 at the corresponding position x0, y0, z0 and / or at the corresponding distance d, the phase distribution imposed by means of the beam splitter element 106 has a specific grating component and / or optical lens component for each focal element 120.

[0136] Due to the grating component, after the focusing of the sub-beams 116, a corresponding site shift of the formed focal element 120 is produced in the first spatial direction and / or the second spatial direction (for example, in the x direction and / or in the y direction). Due to the optical lens component, the sub-beams 116 or the sub-beam clusters impinge on the focusing optical device 118 at different angles or with different degrees of convergence or divergence, which produces a site shift in the third spatial direction, for example, in the z direction, after focusing.

[0137] The intensity I of the respective focal element 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 above-mentioned grating component and optical lens component and can be selected relative to each other when designing the beam splitter element 106 such that each focal element 120 has the desired intensity.

[0138] Alternatively or additionally, it may be provided that the beam splitting element 106 is formed as a polarization beam splitting element or comprises a polarization beam splitting element. In this case, the beam splitting element 106 is used to perform polarization splitting of the input laser beam 108 into beams each having one of at least two different polarization states.

[0139] In particular, the aforementioned polarization states are to be understood as meaning linear polarization states, wherein, for example, two different polarization states are provided and / or polarization states oriented perpendicularly to one another are provided.

[0140] 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).

[0141] For polarization beam splitting, the beam splitting element 106 comprises, for example, a birefringent lens element and / or a birefringent wedge element. For example, the birefringent lens element and / or the birefringent wedge element is made of or comprises a quartz crystal.

[0142] Regarding the working mode and implementation scheme of the beam splitting element 106 as a polarization beam splitting element, reference is made to the German patent application of the same applicant, index number 10 2020 207 715.0 (filing date: June 22, 2020), and reference is made to DE 102019 217 577A1.

[0143] In particular, by polarization beam splitting, sub-beams 116 with different polarization states can be formed. By focusing these sub-beams 116 with the aid of focusing optics 118, focal elements 120 can be formed from beams with a specific polarization state. Therefore, focal elements 120 can each be assigned a specific polarization state and / or can be implemented with a specific polarization state.

[0144] In particular, by polarization splitting by means of the beam splitting element 106, the focal elements 120 can be arranged and formed such that the focal elements 120 adjacent to each other each have a different polarization state.

[0145] For laser processing of workpiece 104, focus element 120 is introduced into material 102 of workpiece 104 and moved relative to material 102 along feed direction 126, wherein focus element 120 is moved in particular at a specific feed rate along feed direction 126. In the example shown, feed direction 126 corresponds to the y direction.

[0146] In order to perform the relative movement of the focal element 120 with respect to the material 102, the apparatus 100 includes a feeding device 127 (e.g. Figure 1As briefly shown). The feed device 127 is configured to move the focus element 120 through the material 102 in the feed direction 126 at a defined feed rate. For example, the feed device can be implemented by means of a workpiece holder, which is configured to move the workpiece 104 arranged thereon relative to the focus element 120.

[0147] The coupling-in of the focus element 120 introduced into the material 102 for laser processing of the workpiece 104 takes place, for example, through the first outer side 130 of the workpiece 104.

[0148] For example, the workpiece 104 is configured as plate-shaped and / or sheet-shaped and / or disk-shaped. The second outer side 132 of the workpiece 104 is arranged, for example, spaced apart from the first outer side 130 in the thickness direction 134 and / or depth direction of the workpiece 104.

[0149] The material 102 of the workpiece 104 has, for example, an at least approximately constant thickness D with respect to the thickness direction 134. The thickness D is, for example, 500 μm.

[0150] The feed direction 126 is transverse to the beam propagation direction 124 and / or the thickness direction 134 of the workpiece 104 and is in particular oriented perpendicular to the beam propagation direction and / or the thickness direction of the workpiece.

[0151] The formed focus elements 120 are preferably arranged such that in their projection onto a projection plane 139 which is transverse to the feed direction 126 and in particular perpendicular to the feed direction, they are positioned along a defined processing line 136 (see Figure 2 and Figure 4 ). The aforementioned projection is in particular understood to mean the orthogonal projection of the focus element 120 onto the projection plane.

[0152] The processing line 136 at least sectionally corresponds to the target processing geometry with which the laser processing of the material 102 is to be carried out and in particular the subsequent breaking of the material 102.

[0153] The focus elements 120 are spaced apart from one another by an effective distance d in the projection plane 139 and / or along the processing line 139 eff . The corresponding effective distance d eff and the intensity I of the focus elements 130 arranged along the processing line 136 are selected such that by loading the material 102 with the focus elements 120 and moving the focus elements 120 through the material 102, a material modification 138 ( Figure 3 ) is produced, which enables the material to be broken along the processing line 136 and / or along the processing surface corresponding to the processing line.

[0154] In particular, it can be set such that the machining line 136 can extend between the first outer side 130 and the second outer side 132 of the workpiece 104, and in particular, it extends continuously and / or without interruption between the first outer side 130 and the second outer side 132.

[0155] It can be set such that the machining line 136 has a plurality of different sections 140. For example, in Figure 2 the example shown, the machining line 136 has a first section 140a, a second section 140b, and a third section 140c, wherein, in terms of the thickness direction 134, the second section 140b is connected to the first section 140a and the third section 140c is connected to the second section 140b.

[0156] The machining line 136 does not necessarily have to be constructed as continuous and / or differentiable. For example, the machining line 136 can have discontinuities. It can be set such that the machining line 136 has interruptions and / or gaps, at which in particular no focus elements 120 are arranged.

[0157] The machining line 136 and / or the different sections 140 of the machining line 136 can for example be formed as straight lines or curves.

[0158] Preferably, two or more planes 141 spaced apart from each other are provided, in which different partial amounts of the formed focus elements 120 are respectively arranged, wherein these planes 141 are spaced apart parallel to the feed direction 126. For example, the planes 141 are each parallel to the projection plane 139 and / or transverse to the feed direction 126 and in particular perpendicular to the feed direction.

[0159] In Figure 5a 、 Figure 5b and Figure 6 the example shown, a partial amount of the formed focus elements 120 is respectively located in the first plane 141a and in a further plane, which in the shown embodiment is referred to as the second plane 141b. The first plane 141a and the second plane 141b are spaced apart from each other in the feed direction 126 and are for example oriented parallel to each other. The focus elements 120 assigned to the first plane 141a are hereinafter referred to as focus elements 120a, and the focus elements 120 assigned to the second plane 141b are hereinafter referred to as focus elements 120b. In Figure 4 the total amounts of the focus elements 120a and 120b are shown in the form of their projections on the projection plane 139.

[0160] In particular, there are focus elements 120a and focus elements 120b, which are arranged at different positions x0, z0 in the projection plane 139.

[0161] The distance d0 between the first plane 141a and the second plane 141b is, for example, between 5 μm and 20 μm. Generally, the distance d0 is approximately 10 μm.

[0162] The distance d mentioned above should in principle be understood as the actual distance between adjacent focus elements 120 in three spatial directions x, y, z and / or in spatial dimensions.

[0163] It is set such that the corresponding distance d between adjacent focus elements 120 is between 3 μm and 70 μm, preferably between 5 μm and 10 μm. In particular, the corresponding distance d between adjacent focus elements 120 arranged in a specific plane 141 lies within the mentioned range.

[0164] As Figure 5a shown by way of example with the focus elements 120a of the first plane 141a, gaps 143 are respectively formed between adjacent focus elements 120 assigned to a specific plane 141.

[0165] The second plane 141b particularly contains focus elements 120b which are positioned such that when viewed in the projection plane 139, they are located in the gaps 143.

[0166] The respective effective distance d of the focus elements 120 used for laser machining of the workpiece 104 can be selected differently for different focus elements 120 and / or different pairings of focus elements 120. eff . However, in principle it is also possible that in all focus elements 120 used for laser machining of the workpiece 104, the distances d are at least approximately the same.

[0167] For example, it can be set such that different sections 140 of the machining line are respectively assigned focus elements 120 with different effective distances d eff . In particular, here, the corresponding distance d of the focus elements 120 assigned to a specific section 140 eff is at least approximately constant.

[0168] In particular, the effective distance component d eff of the effective distance d oriented parallel to the thickness direction 134 of the material 102 and / or perpendicular to the feed direction 126 z,eff is non - zero for all focus elements 120 and / or for all pairings of adjacent focus elements 120. In particular, all adjacent focus elements 120 are spaced apart in the thickness direction 134 by a non - zero effective distance component d z,eff .

[0169] Furthermore, 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, and the processing line 136 or the corresponding section 140 forms the specific angle of attack and / or the angle-of-attack range with the first outer side 130 of the workpiece 104.

[0170] In the case where the angle of attack is between 1° and 89°, the adjacent focus elements 120 respectively have an effective distance d eff and an additional non-zero effective distance component d x,eff which is perpendicular to the feed direction 126 and perpendicular to the effective distance component d z,eff and is oriented.

[0171] The effective distance component d z,eff and the effective distance component d x,eff are each located in a plane oriented perpendicular to the feed direction 126.

[0172] In the illustrated embodiment, the angle of attack α of the first section 140a and the third section 140c is 45° numerically, and the angle of attack α of the second section 140b is 90°.

[0173] By loading and / or introducing the focus elements 120 into the material 102, local material modifications 138 are respectively formed, and these local material modifications are arranged at the corresponding location positions x0, y0, z0 of the corresponding focus elements 120 in the material 102 ( Figure 3 ). By appropriately selecting processing parameters, such as the corresponding distance d between the focus elements 120, their corresponding intensity I, the feed rate oriented along the feed direction 126, and the laser parameters of the input laser beam 108, for example, material modifications 146 of type III modification can be generated, and the material modifications are associated with the spontaneous formation of cracks 137 in the material 102 of the workpiece 104. In particular, cracks 137 are formed between adjacent material modifications 146.

[0174] Alternatively, here, the material modifications 146 can also be configured as type I and / or type II modifications by appropriately selecting processing parameters, and these modifications are accompanied by heat accumulation in the material 102 and / or a change in the refractive index of the material 102. Configuring the material modifications 146 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 modifications 146, the corresponding distance d between the focus elements 120 is selected to be small so that heat accumulation occurs when the material 102 is loaded with the focus elements.

[0175] Figure 7aThe simulated intensity distribution of a plurality of focal elements 120 is shown, wherein the distance d between these focal elements 120 is approximately 17.5 μm. In the grayscale image shown, the brighter regions represent higher intensities.

[0176] Figure 7b The simulated intensity distribution of a plurality of focal elements 120 is shown, wherein the distance d is approximately 8.0 μm.

[0177] The laser machining of the workpiece 104 by means of the device 100 is carried out as follows:

[0178] For performing laser machining, the material 102 of the workpiece 104 is loaded with the focal elements 120, and the focal elements 120 are moved relative to the workpiece 104 in the feed direction 126 through the material 102 of the workpiece.

[0179] Here, the material 102 is a material that is transparent to the wavelength of the laser beam that respectively forms the focal elements 120, such as a glass material. In the example shown, the focal elements are formed by beam shaping of the input laser beam 108.

[0180] By loading the material 102 with the focal elements 120, material modifications 138 are generated in the material 102, and these material modifications are arranged along the machining line 136 in a cross-section oriented perpendicular to the feed direction 126 ( Figure 8a ). In Figure 8a the example shown, the material modifications 138 are formed continuously over the entire thickness D of the material 102.

[0181] By the relative movement of the focal elements 120 relative to the material 102 along a pre-given trajectory 142, a machining surface 144 corresponding to the machining line 136 is formed, and the material modifications 138 are arranged on this machining surface. Thereby, a surface-like structure and / or arrangement of the material modifications 146 along the machining surface 144 is obtained.

[0182] The trajectory 142 can in principle have straight sections and / or curved sections. In the case of a curved section, the machining line 136 is rotated during laser machining, in particular, such that it always lies in a plane oriented perpendicular to the feed direction 126. This can be achieved, for example, by a corresponding rotation of the beam splitter element 106 or by a relative rotation of the entire device 100 relative to the workpiece 104.

[0183] The distance between adjacent material modifications 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 rate.

[0184] The material modification section 146 formed along the machining line 136 particularly results in a reduction in the strength of the material 102. This allows, after the material modification section 146 has been produced on the machining surface 144, for example by applying mechanical force, the material 102 to be broken into two workpiece sections 146a, 146b that are different from each other( Figure 8b ).

[0185] In the example shown, the workpiece section 146a is a finished workpiece section with a fracture surface 148 that has a shape corresponding to the shape of the machining line 136. In this case, the workpiece section 146b is a remaining workpiece section and / or a waste section.

[0186] For example, the material 102 of the workpiece 104 is quartz glass. Here, in order to configure the material modification section 138 as a type-I and / or type-II modification, the laser beam forming the focal element 120 has, for example, a wavelength of 1030 nm and a pulse duration of 1 ps. In addition, the numerical aperture assigned to the focusing optics 118 is 0.4, and the pulse energy assigned to a single focal element 120 is 50 nJ to 200 nJ.

[0187] In order to configure the material modification section 138 as a type-III modification, with other parameters being the same, the pulse energy assigned to a single focal element 120 is 500 nJ to 2000 nJ.

[0188] List of reference numerals

[0189] α angle of attack

[0190] d distance

[0191] d0 distance

[0192] d eff effective distance

[0193] d x,eff effective distance component

[0194] d z,eff effective distance component

[0195] D thickness

[0196] I strength

[0197] x0 position in the x direction

[0198] y0 position in the y direction

[0199] z0 position in the z direction

[0200] 100 device

[0201] 102 material

[0202] 104 workpiece

[0203] 106 beam splitter element

[0204] 108 input laser beam

[0205] 110 laser beam source

[0206] 112 beam cross-section

[0207] 114 wavefront

[0208] 116 sub-beam

[0209] 116a sub-beam

[0210] 116b sub-beam

[0211] 118 focusing optical device

[0212] 120 focus element

[0213] 120a,b focus element

[0214] 121 focus distribution

[0215] 122 beam shaping device

[0216] 124 beam propagation direction

[0217] 126 feed direction

[0218] 127 feed device

[0219] 130 first outer side

[0220] 132 second outer side

[0221] 134 thickness direction

[0222] 136 machining line

[0223] 137 crack

[0224] 138 material modification part

[0225] 139 projection plane

[0226] 140 section

[0227] 140a first section

[0228] 140b second section

[0229] 140c third section

[0230] 141 plane

[0231] 141a first plane

[0232] 141b Second plane

[0233] 142 Locus

[0234] 143 Gap

[0235] 144 Machined surface

[0236] 146a Workpiece section

[0237] 146b Workpiece section

[0238] 148 Split surface

Claims

1. A method for laser processing a workpiece (104) having a transparent material (102), wherein, An input laser beam (108) is split into a plurality of sub - beams (116) by means of a beam - splitting element (106), the sub - beams (116) coupled out from the beam - splitting element (106) are focused, wherein a plurality of focal elements (120) are formed by focusing the sub - beams (116), the material (102) of a workpiece (104) is loaded with the focal elements (120) for laser processing, and the focal elements (120) are moved relative to the material (102) in a feed direction (126). It is characterized in that a partial amount (120a) of the formed focal elements are arranged in a first plane (141a), and a partial amount (120b) of the formed focal elements are arranged in at least one additional plane (141b), wherein the first plane (141a) and the at least one additional plane (141b) are spaced apart parallel to the feed direction (126), and wherein the first plane (141a) and the at least one additional plane (141b) are oriented perpendicular to the feed direction (126).

2. The method according to claim 1, wherein The formed focal elements (120) are positioned such that when the focal elements (120) are observed in a projection plane (139) oriented perpendicular to the feed direction (126), the focal elements (120) assigned to the first plane (141a) and at least a partial amount of the focal elements (120) assigned to the at least one additional plane (141b) are arranged at different spatial positions (x0, y0, z0) in the projection plane (139).

3. The method according to claim 1 or 2, characterized in that The formed focal elements (120) are positioned such that when the focal elements (120) are observed in a projection plane (139) oriented perpendicular to the feed direction (126), the focal elements (120a) assigned to the first plane (141a) and at least a partial amount of the focal elements (120b) assigned to the at least one additional plane (141b) are positioned along a processing line (136) in the projection plane (139), wherein by the relative movement of the focal elements (120) relative to the material (102) in the feed direction (126), a material modification portion (138) arranged along the processing line (136) is formed in the material (102).

4. The method according to claim 3, wherein By the relative movement of the focal elements (120) in the material (102), a material modification portion (138) is formed along a processing surface (144) corresponding to the processing line (136), wherein, in particular, the material modification portion (138) is arranged along the processing line (136) in a cross - section of the processing surface (144) oriented perpendicular to the feed direction (126).

5. The method according to claim 3 or 4, characterized in that, Adjacent focus elements (120) arranged along the processing line (136) have an effective distance (d) of at least 2 μm and / or at most 200 μm in the projection plane (139). eff ) 6. The method according to any one of claims 3 to 5, characterized in that The effective distance (d eff ) between adjacent focus elements (120) arranged along the processing line (136) in the projection plane (139) and / or the intensity (I) of the focus elements (120) are selected such that by loading the material (102) with the focus elements (120) and relative movement of the focus elements (120) relative to the material (102) in the feed direction (126), a material modification (138) is formed in the material (102), which enables the material (102) to be segmented.

7. The method according to any one of claims 3 to 6, characterized in that At least a portion of adjacent focus elements (120) arranged along the processing line (136) are spaced apart from one another in the projection plane (139) at least approximately at the same effective distance (d eff ).

8. The method according to any one of claims 3 to 7, characterized in that, At least some of the focus elements (120) arranged adjacent to one another along the processing line (136) are spaced apart by an effective distance (d eff ), wherein the effective distance (d eff ) has a non-zero effective distance component (d z,eff ) oriented parallel to the thickness direction (134) of the workpiece (104), and / or has another non-zero effective distance component (d x,eff ) oriented perpendicular to the thickness direction (134) of the workpiece (104).

9. The method according to any one of claims 3 to 8, characterized in that, The angle of attack (α) between the processing line (136) and the following outer side surface (130) of the workpiece (104) is at least sectionally at least 1° and / or at most 90°, in particular at most 89°, and the focus element (120) is coupled into the material (102) of the workpiece (104) through the outer side surface for laser processing.

10. The method according to any one of the preceding claims, characterized in that, The formed focus element (120) is positioned such that when observing the focus element (120) in a projection plane (139) oriented perpendicular to the feed direction (126), gaps (143) are respectively formed between adjacent focus elements (120a) assigned to the first plane (141a), and there are focus elements (120b) assigned to the at least one other plane (141b) and arranged in the gaps (143).

11. The method according to any one of the preceding claims, characterized in that, The distance (d) between adjacent focus elements (120a) assigned to the first plane (141a) is at least 3 μm and / or at most 70 μm, and in particular at least 5 μm and / or at most 10 μm, and / or the distance (d) between adjacent focus elements (120b) assigned to the at least one other plane (141b) is at least 3 μm and / or at most 70 μm, and in particular at least 5 μm and / or at most 10 μm.

12. The method according to any one of the preceding claims, characterized in that, The splitting of the input laser beam (108) by means of the beam splitting element (106) is carried out by phase addition on the beam cross-section (112) of the input laser beam (108), or the splitting of the input laser beam by means of the beam splitting element includes phase addition on the beam cross-section (112) of the input laser beam (108).

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

14. The method according to any one of the preceding claims, characterized in that, A material modification (138) is formed in the material (102) by loading the material (102) of the workpiece (104) with the focus element (120), wherein the material modification (138) is accompanied by a change in the refractive index of the material (102), and / or, wherein the material modification (138) is a type I material modification and / or a type II material modification.

15. An apparatus for laser processing a workpiece (104) having a transparent material (102), comprising: A beam splitting element (106) for splitting an input laser beam (108) into a plurality of sub-beams (116); Focusing optical means (118) for focusing a sub-beam (116) coupled out from the beam splitter element (106), wherein a plurality of focus elements (120) for laser machining the workpiece (104) are formed by focusing the sub-beam (116); and a feed device (127) for performing a movement of the focus elements (120) relative to the material (102) of the workpiece (104) in a feed direction (126), characterized in that the beam splitter element (106) and the focusing optical means (118) are configured to arrange the focus elements (120) such that: focus elements of a partial amount (120a) of the formed focus elements are arranged in a first plane (141a), and focus elements of a partial amount (120b) of the formed focus elements are arranged in at least one further plane (141b), wherein the first plane (141a) and the at least one further plane (141b) are spaced apart parallel to the feed direction (126), and wherein the first plane (141a) and the at least one further plane (141b) are oriented perpendicular to the feed direction (126).

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