Method and device for laser processing a workpiece

Abstract

The invention relates to a method for laser processing a workpiece (104), having a transparent material (102), wherein an input laser beam (108) is divided into a plurality of sub-beams (116) by means of a beam splitting element (106), sub-beams (116) coupled out of the beam splitting element (106) are focused, wherein multiple focus elements (120) are formed by focusing the sub-beams (116), the material (102) of the workpiece (104) is applied with the focus elements (120) for the laser processing and the focus elements (120) are moved relative to the material (102) in a feed direction (126), characterised in that a sub-quantity of the formed focus elements (120a) are arranged in a first plane (141a) and a sub-quantity of the formed focus elements (120b) are arranged in at least one other plane (141b), wherein the first plane (141a) and the at least one other plane (141b) are spaced apart in parallel with the feed direction (126) and wherein the first plane (141a) and the at least one other plane (141b) are orientated perpendicular to the feed direction (126).

Description

[0001] Method and device for laser processing a workpiece

[0002] The invention relates to a method for laser processing a workpiece which comprises a transparent material, in which an input laser beam is split into a plurality of partial beams by means of a beam splitting element, partial beams coupled out of the beam splitting element are focused, wherein a plurality of focus elements are formed by focusing the partial beams, the material of the workpiece is subjected to the focus elements for laser processing and the focus elements are moved relative to the material in a feed direction.

[0003] Furthermore, the invention relates to a device for laser processing of a workpiece which has a transparent material, comprising a beam splitting element for splitting an input laser beam into a plurality of partial beams, a focusing optic for focusing partial beams coupled out of the beam splitting element, wherein by focusing the partial beams a plurality of focus elements for laser processing of the workpiece are formed, and a feed device for carrying out a relative movement of the focus elements relative to the material of the workpiece in a feed direction.

[0004] WO 2022 / 167254 A1 and WO 2022 / 167257 A1 each disclose methods and devices for laser processing of a transparent workpiece, wherein the workpiece is subjected to a plurality of focus elements for laser processing.

[0005] From DE 10 2014 116 958 A1, a diffractive optical beam-shaping element for imprinting a phase profile on a laser beam intended for laser processing of a material that is largely transparent to the laser beam is known, said element comprising a phase mask that is designed to imprint a plurality of beam-shaping phase profiles on the laser beam falling on the phase mask, wherein at least one of the plurality of beam-shaping phase profiles is assigned a virtual optical image that can be imaged in at least one elongated focus zone for forming a modification in the material to be processed.

[0006] EP 3 597 353 A1 discloses a method for separating a transparent material by means of an elongated focus zone of a laser beam.

[0007] From JP 2020 004 889 A a method for separating and in particular beveling a transparent material is known, wherein a plurality of focus points for laser processing of the material are generated by means of a spatial light modulator.

[0008] US 2020 / 0147729 A1 and US 2020 / 0361037 A1 each disclose methods for forming a bevelled edge region on a transparent material by means of a laser beam.

[0009] WO 2016 / 089799 A1 discloses a method for separating a transparent material using several parallel non-diffracting laser beams.

[0010] The invention is based on the object of providing a method and a device as mentioned above, by means of which material modifications can be formed in the material of the workpiece, which enable a separation of the material with an improved quality and in particular a reduced roughness at the separation surface.

[0011] This object is achieved according to the invention in the method mentioned at the outset in that a subset of the formed focus elements is arranged in a first plane and a subset of the formed focus 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 processing of the workpiece using the method according to the invention, material modifications are formed in the material of the workpiece, which in particular enable a separation of the material. By arranging focus elements both in the first plane and in the at least one further plane, an effective distance between the focus elements oriented perpendicular to the feed direction can be reduced. As a result, adjacent material modifications in the material of the workpiece can be formed with a particularly small distance, which in turn increases the density of the material modifications formed in the material. This makes it possible to improve the separability of the material. In addition, the quality of a separation surface resulting from the separation of the material can be increased, wherein the separation surface can be designed in particular with reduced roughness and / or increased smoothness.This results in increased edge stability of the workpiece material at the cutting surface after the cutting process.

[0013] If the actual distance between adjacent focus elements becomes too small, undesirable interference effects can arise between adjacent focus elements, which can, for example, result in beat effects in the intensity of the focus elements. This can make it difficult to control the formation of the material modifications and, in particular, to form similar material modifications. In the solution according to the invention, the focus elements are arranged "offset" in the feed direction to form the material modifications, resulting in a significantly reduced effective distance with a sufficiently large actual distance between the focus elements.

[0014] The distance or real distance between focus elements is the actual distance between these focus elements in three-dimensional space. The effective distance between the focus elements is the distance from perpendicular projections of the focus elements into a projection plane oriented perpendicular to the feed direction.

[0015] A spatial position and / or arrangement of a specific focal element is understood to mean, in particular, that of its center and / or center of gravity within the material. In particular, the distance and the effective distance are related to the corresponding centers of the focal elements in the material, i.e., they are center-to-center distances.

[0016] By relative movement of the focus elements arranged in the first plane and the at least one further plane with respect to the material in the feed direction, material modifications are formed at least in sections of the material, which are spaced apart by the effective distance.

[0017] With the method according to the invention, the material modifications can be formed in such a way that adjacent material modifications overlap within the material. This results in a crack connection between the adjacent material modifications, which enables particularly good separability of the material by etching or thermal treatment.

[0018] By applying the focus elements to the material of the workpiece at a specific time, material modifications are formed which are arranged in the material at positions at which the focus elements are positioned in the material at that time.

[0019] In particular, all focus elements assigned to the first level and / or the at least one further level are present simultaneously.

[0020] For example, two or more planes oriented perpendicular to the feed direction can be provided, each of which contains a subset of the formed focus elements. The provided planes are each oriented parallel to one another and / or spaced apart from one another in the feed direction.

[0021] In particular, it can be provided that a distance between the first plane and the at least one further plane is at least 2 pm and / or at most 200 pm. For example, the distance is approximately 10 pm. In particular, it can be provided that the formed focus elements are positioned such that, when viewing the focus elements in a projection plane oriented perpendicular to the feed direction, at least a subset of the focus elements assigned to the first plane and the focus elements assigned to the at least one further plane are arranged at different spatial positions in the projection plane. This makes it possible to reduce the effective distance between adjacent focus elements, so that a distance between formed adjacent material modifications is correspondingly reduced.

[0022] In particular, it can be provided that the formed focus elements are positioned such that, when viewing the focus elements in a projection plane oriented perpendicular to the feed direction, at least a subset of the focus elements assigned to the first plane and the focus elements assigned to at least one further plane are positioned in the projection plane along a processing line. Material modifications are formed in the material by the relative movement of the focus elements with respect to the material in the feed direction, which material modifications are arranged along the processing line. By means of the processing line, in particular, an edge geometry and / or a cross-sectional geometry of a separation surface resulting from the separation of the material at the material modifications can be defined.

[0023] For example, the at least one processing line has a total length between 10 pm and 10,000 pm, and in particular between 100 pm and 1,000 pm, and in particular between 400 pm and 600 pm. This allows workpieces with a thickness within the specified range to be processed and, in particular, cut.

[0024] The material of the workpiece has, for example, a thickness between 10 pm and 10,000 pm and preferably between 100 pm and 1,000 pm, for example approximately 500 pm.

[0025] In particular, it can be provided that the processing line is spatially continuous over a thickness of the material of the workpiece and / or over a thickness of a workpiece segment to be separated from the workpiece.

[0026] The processing line is not necessarily spatially continuous, but may comprise various spatially separated sections. In particular, the processing line may have interruptions in which no focus elements are arranged.

[0027] In particular, the relative movement of the focus elements in the material creates material modifications along a processing surface corresponding to the processing line. The material modifications are then arranged along the processing line, particularly when viewed in a cross-section through the processing surface oriented perpendicular to the feed direction. After the workpiece has been separated at the material modifications arranged along the processing surface, a shape and / or cross-sectional shape of the separation surface formed during the separation corresponds, in particular, to a shape and / or cross-sectional shape of the (previous) processing surface.

[0028] It can be advantageous if adjacent focus elements arranged along the processing line have an effective spacing of at least 2 pm and / or at most 200 pm in the projection plane. This allows the cutting surface to be produced with particularly high quality and / or reduced roughness.

[0029] The focus elements arranged along the processing line and / or viewed in the projection plane are understood to be the focus elements which are assigned to the first plane and to at least one further plane.

[0030] In particular, the effective distance of the focus elements along the machining line corresponds at least approximately to a distance of material modifications which are formed on the machining surface corresponding to the machining line and are positioned in a cross-section through the machining surface oriented perpendicular to the feed direction.

[0031] In particular, it can be provided that an effective distance between adjacent focus elements arranged along the processing line in the projection plane and / or an intensity of the focus elements is selected such that by applying the focus elements to the material and relative movement of the focus elements with respect to the material in the feed direction, material modifications are formed in the material which enable a separation of the material.

[0032] In particular, it can be provided that at least a subset of adjacent focus elements arranged along the processing line are spaced apart from one another in the projection plane at least approximately by the same effective distance.

[0033] It may be advantageous for at least a subset of adjacent focus elements arranged along the processing line to be spaced apart by an effective distance, wherein the effective distance has an effective distance component that is non-zero and oriented parallel to a thickness direction of the workpiece, and / or has a further effective distance component that is non-zero and oriented perpendicular to the thickness direction of the workpiece. This allows, for example, a perpendicular cut to be made on the workpiece or the workpiece to be chamfered at a specific angle.

[0034] The thickness direction of the workpiece is to be understood in particular as a direction which is oriented transversely and in particular perpendicular to an outer side of the workpiece, through which the focus elements and / or a laser beam are coupled into the material to form the focus elements.

[0035] The thickness direction is oriented in particular transversely or perpendicularly to a beam propagation direction of a laser beam from which the focus elements are formed.In particular, it can be provided that at least a subset of mutually adjacent focus elements which are arranged along the processing line are spaced apart by an effective distance, wherein the effective distance has an effective distance component which is different from zero and is oriented parallel to a beam propagation direction of a laser beam from which the focus elements are formed, and / or that at least a subset of mutually adjacent focus elements which are arranged along the processing line are spaced apart by an effective distance, wherein the effective distance has an effective distance component which is different from zero and is oriented perpendicular to a beam propagation direction of a laser beam from which the focus elements are formed.

[0036] For the same reason, it may be advantageous if the angle of attack between the processing line and an outer side of the workpiece, through which the focus elements for laser processing are coupled into the workpiece material, is at least partially at least 1° and / or at most 90°, and in particular at most 89°. Depending on the selected angle of attack, this allows, for example, a vertical cut to be made on the workpiece or the workpiece to be chamfered at a specific angle.

[0037] The fact that the processing line has a certain angle of attack or angle of attack range at least in sections is to be understood in particular that the processing line has at least one section with this angle of attack or angle of attack range.

[0038] 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°, particularly preferably at least 40° and / or at most 50°.

[0039] In particular, it can be provided that the angle of attack of the processing line is constant at least in sections, and / or that the processing line has several sections with different angles of attack. In particular, it can be provided that the processing line is a straight line at least in sections, and / or that the processing line is a curve at least in sections.

[0040] By executing the machining line as a curve, rounded segments can be cut off from the workpiece, for example, creating rounded edges.

[0041] When the machining line is designed as a curve, for example, the machining line is assigned a specific angle of attack range which the machining line has with respect to the outside of the workpiece.

[0042] It may be advantageous if the formed focus elements are positioned such that, when viewed in a projection plane oriented perpendicular to the feed direction, gaps are formed between adjacent focus elements assigned to the first plane, wherein focus elements assigned to the at least one further plane are present and arranged in the gaps. This allows the effective spacing between adjacent focus elements to be reduced and / or the density of material modifications formed in the material to be increased.

[0043] In particular, it can be provided that a distance between adjacent focus elements which are assigned to the first plane is at least 3 pm and / or at most 70 pm and in particular at least 5 pm and / or at most 10 pm.

[0044] In particular, it can be provided that a distance between adjacent focus elements which are assigned to the at least one further plane is at least 3 pm and / or at most 70 pm and in particular at least 5 pm and / or at most 10 pm.

[0045] In particular, it may be provided that a division of the

[0046] The input laser beam is split by means of the beam splitting element by phase imprinting on a beam cross-section of the input laser beam or by phase imprinting on a beam cross-section of the input laser beam. This allows the focus elements to be formed, for example, as copies of one another. In particular, this allows the focus elements to be introduced into the workpiece material in a technically simple manner at different positions and / or at different distances.

[0047] It can be provided that the division of the input laser beam is carried out exclusively by phase imposition on the beam cross-section of the input laser beam.

[0048] In particular, the phase imprint 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.

[0049] Alternatively or additionally, the input laser beam can be split by the beam splitting element through polarization beam splitting or by polarization beam splitting. This allows, for example, adjacent focus elements to be formed with different polarization states. This, in particular, prevents interference between adjacent focus elements, allowing them to be arranged at a particularly close distance from one another.

[0050] It is fundamentally possible for the input laser beam to be split using both phase imprinting and polarization beam splitting.

[0051] In particular, the input laser beam and / or a laser beam from which the focus elements are formed is a pulsed laser beam, and in particular an ultrashort pulse laser beam. By applying the focus elements to the material, laser pulses, and in particular ultrashort laser pulses, are introduced into the material. The material modifications introduced into transparent materials by ultrashort laser pulses are divided into three different classes, see K. Itoh et al., "Ultrafast Processes for Bulk Modification of Transparent Materials," 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 a so-called void. The type of material modification created by a specific focus element depends on the laser parameters of the laser beam from which the corresponding focus element is formed, such as:the pulse duration, wavelength, pulse energy, and repetition frequency of the laser beam. Furthermore, the type of modification depends on the material's properties, including its electronic structure and thermal behavior.

[0052] Expansion coefficient of the material, as well as the numerical aperture (NA) used to focus the laser beam into the corresponding focus element.

[0053] Type I isotropic refractive index changes are attributed to localized melting by the laser pulses and rapid resolidification of the transparent material. For example, in fused silica, the density and refractive index of the material are higher when the fused silica is rapidly cooled from a higher temperature. Thus, if the material melts in the volume covered by the focus element and then cools rapidly, the fused silica exhibits a higher refractive index in the modified areas than in the unmodified areas.

[0054] Type II birefringent refractive index changes can arise, for example, from interference between an ultrashort laser pulse and the electric field of the plasma generated by the laser pulse. This interference leads to periodic modulations in the electron plasma density, which, upon solidification, results in a birefringent property—i.e., direction-dependent refractive indices—of the transparent material. A type II modification, for example, is also associated with the formation of so-called nanogratings. The voids (cavities) of type III modifications can be created, in particular, with high laser pulse energy. The formation of the voids is attributed to an explosive expansion of highly excited, vaporized material from the focal volume into the surrounding material. This process is also referred to as a microexplosion.Because this expansion occurs within the bulk of the material, the microexplosion leaves behind a less dense or hollow core (the void), or a microscopic defect at the submicrometer or atomic level, surrounded by a dense material shell. The densification at the shock front of the microexplosion creates stresses in the transparent material, which regularly lead to or promote spontaneous crack formation.

[0055] Therefore, when a Type III modification is introduced, a less dense or hollow core, or a defect, is always present. For example, in sapphire, a Type III modification does not create a cavity through microexplosion, but rather a region of lower density.

[0056] In particular, the formation of voids can also be accompanied by Type I and Type II modifications. For example, Type I and Type II modifications can arise in the less stressed areas around the applied laser pulses. The formation of Type I and Type II modifications cannot be completely prevented or avoided by introducing Type III modifications. Therefore, the discovery of "pure" Type III modifications is unlikely.

[0057] It can be advantageous if, by applying the focus elements to the workpiece material, material modifications are formed in the material, wherein the material modifications are accompanied by crack formation in the material and / or wherein the material modifications are Type III material modifications. In particular, these material modifications can be used to separate the material.

[0058] It may be advantageous if material modifications are formed in the material by applying the focus elements to the workpiece material, wherein the material modifications are accompanied by a change in the refractive index of the material, and / or wherein the material modifications are Type I material modifications and / or Type II material modifications. In particular, these material modifications can be used to separate the material.

[0059] In particular, it can be provided that the material of the workpiece is separable or is separated after laser processing, wherein it can be provided in particular that the material is separable or is separated on a processing surface on which material modifications were formed by means of laser processing.

[0060] In particular, it can be provided that the material of the workpiece is separable or is separated by applying thermal stress and / or mechanical tension and / or by etching using at least one wet chemical solution. For example, the etching takes place in an ultrasonic-assisted etching bath. The thermal stress can be applied, for example, using a CO2 laser.

[0061] According to the invention, it is provided in the device mentioned at the outset that the beam splitting element and the focusing optics are designed to arrange the focus elements in such a way that a subset of the formed focus elements is arranged in a first plane and a subset of the formed focus 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.

[0062] 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 already been explained in connection with the method according to the invention. In particular, the method according to the invention can be carried out using the device according to the invention or the method according to the invention is carried out using the device according to the invention.

[0063] It may be advantageous if the beam splitting element is designed as a 3D beam splitting element or comprises a 3D beam splitting element. In this case, the splitting of the input laser beam can be achieved by phase imprinting on a beam cross-section of the input laser beam, and in particular exclusively by phase imprinting on the beam cross-section of the input laser beam.

[0064] It may be advantageous if the beam splitting element is designed as a polarization beam splitting element or comprises a polarization beam splitting element.

[0065] For example, the beam splitting element comprises multiple components and / or functionalities. It can be provided that the beam splitting element comprises both a 3D beam splitting element and a polarization beam splitting element.

[0066] In particular, the device comprises a laser beam source for providing the input laser beam, wherein the input laser beam is in particular a pulsed laser beam and / or an ultrashort pulse laser beam.

[0067] A transparent material is understood to mean, in particular, a material through which at least 70% and in particular at least 80% and in particular at least 90% of a laser energy of the input laser beam and / or a laser energy of a laser beam from which the focus elements are formed is transmitted.

[0068] In particular, a focus element is understood to be a radiation area with a specific spatial extent and intensity distribution. To determine the spatial dimensions of a specific focus element, such as the diameter of the focus element, only intensity values ​​of the intensity distribution that lie above a certain intensity threshold are considered. The intensity threshold is chosen, for example, such that values ​​below this intensity threshold have such a low intensity that they are no longer relevant for interaction with the material to form material modifications. For example, the intensity threshold is 50% of a global intensity maximum of the focus element.

[0069] In particular, a specific focus element is assigned a spatial interaction area in which the focus element interacts with the material of the workpiece when it is introduced into it.

[0070] In particular, the focus elements introduced into the material interact with the material through nonlinear absorption. In particular, the focus elements create material modifications in the material due to nonlinear absorption.

[0071] In particular, it can be provided that the respective focus elements according to the above definition have a maximum spatial extent of at least 0.5 pm and / or at most 30 pm, preferably at least 2 pm and / or at most 10 pm. In particular, a maximum spatial extent of an interaction region associated with a specific focus element with the material of the workpiece is at least 0.5 pm and / or at most 30 pm, and preferably at least 2 pm and / or at most 10 pm.

[0072] The maximum spatial extent of a particular focus element is understood to mean, in particular, the largest spatial extent of the focus element in any spatial direction.

[0073] In particular, a respective maximum spatial extent of the focus elements is less than 20% and preferably less than 10% and particularly preferably less than 5% of a thickness of the material.

[0074] In particular, the focus elements have a diffractive beam profile. In particular, the focus elements are designed to be diffraction-limited. For example, a specific focus element has a Gaussian shape and / or a Gaussian intensity profile.

[0075] In particular, the input laser beam and / or a laser beam from which the focus elements are formed has a diffractive beam profile and / or a Gaussian beam profile.

[0076] For example, a wavelength of the input laser beam and / or the laser beam from which the focus elements are formed is at least 300 nm and / or at most 1500 nm. For example, the wavelength is 515 nm or 1030 nm.

[0077] In particular, the input laser beam and / or the laser beam from which the focus elements are formed has an average power of at least 1 kW to 1 kW. For example, the laser beam comprises pulses with a pulse energy of at least 10 pJ and / or at most 50 mJ. The laser beam can be provided as individual pulses or bursts, with the bursts having 2 to 20 subpulses and, in particular, a time interval of approximately 20 ns.

[0078] The statement "at least a subset of the focus elements" can be understood to mean either a subset of the focus elements or a total set of the focus elements, i.e. all focus elements.

[0079] In particular, the terms "at least approximately" or "approximately" generally mean a deviation of no more than 10%. Unless otherwise stated, the terms "at least approximately" or "approximately" specifically mean that an actual value and / or distance and / or angle deviates by no more than 10% from an ideal value and / or distance and / or angle.

[0080] The following description of preferred embodiments, in conjunction with the drawings, serves to explain the invention in more detail. Figure 1 shows a schematic representation of an embodiment of a device for laser processing a workpiece;

[0081] Fig. 2 is a schematic cross-sectional view of a portion of a material of the workpiece in which the material is subjected to a plurality of focus elements for laser processing;

[0082] Fig. 3 is a schematic cross-sectional view of a section of the workpiece in which material modifications were produced by applying focus elements to the workpiece, which modifications are accompanied by crack formation in the material;

[0083] Fig. 4 shows an arrangement of focus elements designed for laser processing of the workpiece, wherein a projection of the focus elements is shown in a projection plane oriented perpendicular to the feed direction;

[0084] Fig. 5a shows an arrangement of focus elements designed for laser processing of the workpiece in a cross-section oriented parallel to the feed direction and the thickness direction of the workpiece;

[0085] Fig. 5b the focus elements according to Fig. 5a in a cross-section oriented parallel to the feed direction and perpendicular to the thickness direction of the workpiece;

[0086] Fig. 6 shows the focus elements according to Fig. 5a and 5b in a perspective view;

[0087] Fig. 7a shows a cross-sectional view of a simulated intensity distribution of focus elements for laser processing of the workpiece, wherein adjacent focus elements are each spaced apart by a distance of approximately 17.5 μm; Fig. 7b shows a cross-sectional view of a simulated intensity distribution of focus elements for laser processing of the workpiece, wherein adjacent focus elements are each spaced apart by a distance of approximately 8.0 μm;

[0088] Fig. 8a is a schematic perspective view of a workpiece with material modifications formed thereon, which extend along a machining line and / or machining surface; and

[0089] Fig. 8b is a schematic perspective view of two workpiece segments formed by separating the workpiece according to Fig. 8a along the machining line and / or machining surface.

[0090] Identical or functionally equivalent elements are provided with the same reference numerals in all figures.

[0091] An embodiment of a device for laser processing a workpiece is shown in Fig. 1 and designated by 100. Using the device 100, localized material modifications, such as defects in the submicrometer range or atomic range, can be created in a material 102 of the workpiece 104, which result in a weakening of the material. The workpiece 104 can be separated at these material modifications, whereby, for example, a workpiece segment can be separated from the workpiece 104.

[0092] In particular, by means of the device 100, material modifications can be introduced into the material 102 at an angle of incidence, so that by separating a workpiece segment from the workpiece 104, an edge region of the workpiece 104 can be chamfered or beveled.

[0093] The device comprises a beam splitting element 106, into which a particularly collimated input laser beam 108 is coupled. This input laser beam 108 is provided by a laser beam source 110. In particular, the input laser beam 108 is a pulsed laser beam and / or an ultrashort pulse laser beam.

[0094] It can be provided that the laser beam source 110 comprises a hollow-core fiber (not shown) from which a laser beam generated by the laser beam source emerges. This laser beam is then collimated, for example, by means of collimation optics (not shown) of the laser beam source 110 to form the collimated input laser beam 108.

[0095] The input laser beam 108 is understood, in particular, to be a beam bundle comprising a plurality of, in particular, parallel beams. The input laser beam 108 has, in particular, a transverse beam cross-section 112 and / or a transverse beam extension with which the input laser beam 108 impinges on the beam splitting element 106. The input laser beam 108 impinging on the beam splitting element 106 has, in particular, at least approximately planar wavefronts 114.

[0096] By means of the beam splitting element 106, the input laser beam 108 is split into a plurality of partial beams 116 and / or partial beam bundles. In the example shown in Fig. 1, two mutually different partial beams 116a and 116b are indicated.

[0097] In particular, the beam splitting element 106 is designed as a far-field beam shaping element. The partial beams 116 or partial beam bundles coupled out of the beam splitting element 106 have, in particular, a divergent beam profile and / or propagate in a spherical wave pattern.

[0098] To focus the partial beams 116 coupled out of the beam splitting element 106, the device 100 comprises a focusing optics 118 into which the partial beams 116 are coupled. The focusing optics 118 comprises, for example, one or more lens elements. For example, the focusing optics 118 is designed as a microscope objective. For example, the focusing optics 118 has a focal length between 5 mm and 50 mm.

[0099] The beam splitting element 106 is in particular arranged at least approximately in a rear focal plane of the focusing optics 118.

[0100] In particular, different partial beams 116 impinge on the focusing optics 118 with a spatial offset and / or angular offset. These partial beams 116 are focused by the focusing optics 118, forming a plurality of focus elements 120, each arranged at different spatial positions. It is generally possible for adjacent focus elements to spatially overlap in sections.

[0101] For example, one or more partial beams 116 and / or partial beam bundles are assigned to a specific focus element 120. For example, a respective focus element 120 is formed by focusing one or more partial beams 116 and / or partial beam bundles.

[0102] A focus element 120 is understood, in particular, to be a focused radiation region, such as a focus spot and / or a focal point. In particular, the focus elements 120 each have a specific geometric shape and / or a specific intensity profile, wherein the geometric shape is understood, for example, to be a spatial shape and / or spatial extent of the respective focus element 120.

[0103] The geometric shape and / or intensity profile of a specific focus element 120 is referred to below as the focus distribution 121 of the focus element 120. The focus distribution 121 is a property of the respective focus elements 120 and describes their respective shape and / or intensity profile. In particular, multiple focus elements 120 or all formed focus elements 120 have the same focus distribution.

[0104] The focus distribution of the formed focus elements 120 is defined by the input laser beam 108, the focus elements 120 being formed by splitting the input laser beam 108 by means of the beam splitting element 106. If the input laser beam 108 were focused before being coupled into the beam splitting element 106, a single focus element would be formed with the focus distribution associated with the input laser beam 108.

[0105] For example, the input laser beam 108, when provided, for example, by the laser beam source 110, has a Gaussian beam profile. By focusing the input laser beam 108, a focus element would be formed in this case, which has a focus distribution with a Gaussian shape and / or a Gaussian intensity profile.

[0106] Alternatively, it may be provided, for example, that a Bessel-like beam profile is assigned to the input laser beam 108, so that by focusing the input laser beam 108, a focus element would be formed which has a focus distribution with a Bessel-like shape and / or a Bessel-like intensity profile.

[0107] The focus distribution of the input laser beam 108 is assigned to the partial beams 116 and / or partial beam bundles formed by splitting the input laser beam 108 by means of the beam splitting element 106 in such a way that by focusing the partial beams 116, the focus elements 120 are formed with this focus distribution and / or with a focus distribution based on this focus distribution.

[0108] In the example shown in Fig. 1, the input laser beam 108 has a Gaussian beam profile, i.e., a focus distribution with a Gaussian shape and / or Gaussian intensity profile is assigned to the input laser beam 108. The focus elements 120 then each have, for example, the focus distribution 121 with this Gaussian shape and / or this Gaussian intensity profile or with a shape and / or intensity profile based on this Gaussian shape and / or this Gaussian intensity profile (see also Figs. 5a and 5b).

[0109] If, for example, a Bessel-type beam profile is assigned to the input laser beam 108, the focus elements 120 configured for laser processing the workpiece 104 each have a focus distribution 121 with this Bessel-type beam profile or with a beam profile based on this Bessel-type profile. The focus elements 120 can thus be configured, for example, with a focus distribution having an elongated shape and / or an elongated intensity profile.

[0110] It can be provided that the device 100 has a beam-shaping device 122 for beam-shaping the input laser beam 108 (indicated in Fig. 1). For example, this beam-shaping device 122 is arranged upstream of the beam-splitting element 106 with respect to a beam propagation direction 124 of the input laser beam 108 and / or arranged between the laser beam source 110 and the beam-splitting element 106.

[0111] The beam propagation direction is understood to mean, in particular, a main beam propagation direction and / or a mean propagation direction of a laser beam and / or beam bundle. The beam propagation direction corresponds, in particular, to the direction of a Poynting vector associated with the laser beam or beam bundle.

[0112] By means of the beam shaping device 122, a specific beam profile can be assigned to the input laser beam 108, which defines the focus distribution 121 of the focus elements 120.

[0113] The beam-shaping device 122 can, for example, be configured to form a laser beam with a quasi-non-diffracting and / or Bessel-like beam profile from a laser beam with a Gaussian beam profile. For this purpose, the beam-shaping device 122 is or comprises, for example, an axicon element.

[0114] The input laser beam 108 coupled into the beam splitting element 106 then has the quasi-non-diffracting and / or Bessel-like beam profile. Accordingly, 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. Regarding the definition and realization of quasi-non-diffracting and / or Bessel-like beams, reference is made to the book "Structured Light Fields: Applications in Optical Trapping, Manipulation and Organization," by M. Wördemann, Springer Science & Business Media (2012), ISBN 978-3-642-29322-1, as well as to the scientific publications "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: 1911.03103vl [physics. optics], November 8, 2019.

[0115] By beam splitting by means of the beam splitting element 106, the focus elements 120 are in particular each formed identically to one another and / or each formed as copies of one another.

[0116] Each of the formed focus elements 120 is assigned a specific local position xo, yo, zo, at which a respective focus element 120 is arranged relative to the material 102 of the workpiece 104 (Fig. 2). For example, the local position of a focus element 120 is understood to be the position of its spatial center and / or center of gravity.

[0117] Furthermore, in particular, each of the formed focus elements 120 is assigned a specific intensity I. By means of the beam splitting element 106, the local position xo, yo, zo and in particular also the intensity I of the respective focus elements 120 can be defined.

[0118] In particular, several or all focus elements 120 designed for laser processing of the workpiece 104 have the same intensity I. However, it is also possible for several of the focus elements 120 designed to have different intensities I.

[0119] In particular, by means of the beam splitting element 106, a respective distance d and / or a respective spatial offset between adjacent focus elements 120 can be adjusted component by component in three spatial directions and / or spatial dimensions (in the example shown in Fig. 1 in the x-, y- and z-directions).

[0120] Preferably, the beam splitting element 106 is designed as a 3D beam splitting element or comprises a 3D beam splitting element. The focus elements 120 can thus be designed, for example, such that they are identical to one another and / or that they represent copies of one another.

[0121] Regarding the technical implementation and properties of the beam splitting element 106, which is designed as a 3D beam splitting element, reference is made to the scientific publication "Structured light for ultrafast laser micro- and nanoprocessing" by D. Flamm et al., arXiv:2012.10119vl [physics. optics], December 18, 2020. This publication is expressly incorporated by reference in its entirety.

[0122] To perform the beam splitting, in one embodiment of the beam splitting element 106, in which the beam splitting element 106 is designed, for example, as a 3D beam splitting element, a defined transverse phase distribution is impressed on the transverse beam cross-section 112 of the input laser beam 108. A transverse beam cross-section or a transverse phase distribution is understood to mean, in particular, a beam cross-section or a phase distribution in a plane oriented transversely and, in particular, perpendicularly to the beam propagation direction 124 of the input laser beam 108.

[0123] The focus elements 120 are formed by interference of the focused partial beams 116, wherein, for example, constructive interference, destructive interference or intermediate cases thereof may occur, such as partially constructive or destructive interference.

[0124] To form the focus elements 120 at the respective position xo, yo, zo and / or with the respective distance d, the phase distribution imposed by the beam splitting element 106 has a specific optical grating component and / or optical lens component for each focus element 120. Due to the optical grating component, after focusing the partial beams 116, a corresponding spatial offset of the formed focus elements 120 results in a first spatial direction and / or second spatial direction, e.g., in the x- and / or y-direction. Due to the optical lens component, partial beams 116 or partial beam bundles impinge on the focusing optics 118 at different angles or with different convergence or divergence, which, after focusing, results in a spatial offset in a third spatial direction, e.g., in the z-direction.

[0125] The intensity I of the respective focus elements 120 is determined by the phase positions of the focused partial beams 116 relative to one another. These phase positions can be defined by the aforementioned optical grating components and optical lens components and can be selected relative to one another during the design of the beam splitting element 106 such that the focus elements 120 each exhibit a desired intensity.

[0126] Alternatively or additionally, the beam splitting element 106 may be configured as a polarization beam splitting element or comprise a polarization beam splitting element. In this case, the beam splitting element 106 performs a polarization beam splitting of the input laser beam 108 into beams each having one of at least two different polarization states.

[0127] In particular, the polarization states mentioned are to be understood as linear polarization states, wherein, for example, two different polarization states are provided and / or polarization states oriented perpendicular to each other are provided.

[0128] In particular, the polarization states are such that an electric field is oriented in a plane perpendicular to the beam propagation direction of the polarized rays (transverse electric).

[0129] For polarization beam splitting, the beam splitting element 106 comprises, for example, a birefringent lens element and / or a birefringent wedge element. The birefringent lens element and / or the birefringent wedge element are, for example, made of a quartz crystal or comprise a quartz crystal.

[0130] With regard to the functionality and design of the beam splitting element 106 as a polarization beam splitting element, reference is made to the German patent application with file number 10 2020 207 715.0 (filing date: June 22, 2020) of the same applicant and to DE 10 2019 217 577 A1.

[0131] By splitting the polarization beams, in particular, the partial beams 116 can be formed with different polarization states. By focusing these partial beams 116 using the focusing optics 118, the focus elements 120 can each be formed from beams with a specific polarization state. The focus elements 120 can thus each be assigned a specific polarization state and / or designed with a specific polarization state.

[0132] In particular, by polarization beam splitting by means of the beam splitting element 106, the focus elements 120 can be arranged and formed such that adjacent focus elements 120 each have different polarization states.

[0133] For laser processing of the workpiece 104, the focus elements 120 are introduced into the material 102 of the workpiece 104 and moved relative to the material 102 in the feed direction 126, wherein the focus elements 120 are moved in the feed direction 126, in particular, at a specific feed rate. In the example shown, the feed direction 126 corresponds to the y-direction.

[0134] To perform a relative movement of the focus elements 120 to the material 102, the device 100 comprises a feed device 127 (indicated in Fig. 1). The feed device 127 is configured to move the focus elements 120 in the feed direction 126 at a defined feed rate through the material 102. For example, the feed device can be implemented by means of a workpiece holder configured to move the workpiece 104 arranged thereon relative to the focus elements 120.

[0135] The coupling of the focus elements 120, which are introduced into the material 102 for laser processing of the workpiece 104, takes place, for example, through a first outer side 130 of the workpiece 104.

[0136] For example, the workpiece 104 is plate-shaped and / or panel-shaped and / or disc-shaped. A second outer side 132 of the workpiece 104 is arranged at a distance from the first outer side 130, for example, in the thickness direction 134 and / or depth direction of the workpiece 104.

[0137] 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 pm.

[0138] The feed direction 126 is oriented transversely and in particular perpendicularly to the beam propagation direction 124 and / or to the thickness direction 134 of the workpiece 104.

[0139] The formed focus elements 120 are preferably arranged such that they are positioned along a defined processing line 136 in a projection onto a projection plane 139 oriented transversely and in particular perpendicularly to the feed direction 126 (see Fig. 2 and Fig. 4). This projection is understood, in particular, to mean an orthogonal projection of the focus elements 120 onto the projection plane.

[0140] The processing line 136 corresponds at least in sections to a target processing geometry with which the laser processing of the material 102 and in particular a subsequent separation of the material 102 is to be carried out.

[0141] The focus elements 120 are spaced apart from one another by an effective distance deff in the projection plane 139 and / or along the processing line 139. The respective effective distances deff and intensities I of the focus elements 130 arranged along the processing line 136 are selected such that, by applying the focus elements 120 to the material 102 and moving the focus elements 120 through the material 102, material modifications 138 are formed (Fig. 3), which enable a separation of the material along this processing line 136 and / or along a processing surface corresponding to this processing line 136.

[0142] In particular, it can be provided that the processing line 136 extends between the first outer side 130 and the second outer side 132 and in particular continuously and / or uninterruptedly between the first outer side 130 and the second outer side 132 of the workpiece 104.

[0143] It can be provided that the processing line 136 has a plurality of different sections 140. For example, in the example shown in Fig. 2, the processing 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.

[0144] The processing line 136 is not necessarily continuous and / or differentiable. For example, the processing line 136 may have discontinuities. It may be provided that the processing line 136 has interruptions and / or gaps, at which, in particular, no focus elements 120 are arranged.

[0145] The processing line 136 and / or different sections 140 of the processing line 136 can be designed, for example, as a straight line or a curve.

[0146] Preferably, two or more mutually spaced planes 141 are provided, in each of which different subsets of the formed focus elements 120 are arranged, wherein the planes 141 are spaced parallel to the feed direction 126. For example, the planes 141 are each oriented parallel to the projection plane 139 and / or transversely and in particular perpendicularly to the feed direction 126.

[0147] In the example shown in Figs. 5a, 5b and 6, a subset of the formed focus elements 120 is positioned in a first plane 141a and a further plane, which in the illustrated embodiment is referred to as the second plane 141b. The first plane 141a and the second plane 141b are spaced from one another in the feed direction 126 and are oriented parallel to one another, for example. The focus elements 120 assigned to the first plane 141a are referred to below as focus elements 120a, and the focus elements 120 assigned to the second plane 141b are referred to below as focus elements 120b. Fig. 4 shows a total set of focus elements 120a and 120b in the form of a projection of these focus elements 120a and 120b onto the projection plane 139.

[0148] In particular, focus elements 120a and focus elements 120b are present, which are arranged in the projection plane 139 at different positions xo, zo.

[0149] A distance d0 between the first plane 141a and the second plane 141b is, for example, between 5 pm and 20 pm. Typically, the distance d0 is approximately 10 pm.

[0150] The distance d already mentioned above is basically to be understood as the real distance between adjacent focus elements 120 in the three spatial directions x, y, z and / or spatial dimensions.

[0151] It is intended that the respective distance d between adjacent focus elements 120 is between 3 pm and 70 pm, preferably between 5 pm and 10 pm. In particular, the respective distance d between adjacent focus elements 120 arranged within a specific plane 141 lies within the aforementioned ranges.

[0152] Gaps 143 are formed between adjacent focus elements 120, which are assigned to a specific plane 141, as shown in Fig. 5a using the example of the focus elements 120a of the first plane 141a.

[0153] The second plane 141b contains in particular focus elements 120b, which are positioned such that they lie in the gaps 143 when viewed in the projection plane 139.

[0154] The respective effective distance deff of the focus elements 120 provided for laser processing of the workpiece 104 can be selected differently for different focus elements 120 and / or different pairs of focus elements 120. However, it is also fundamentally possible for the respective distance d to be at least approximately identical for all focus elements 120 provided for laser processing of the workpiece 104.

[0155] For example, it can be provided that different sections 140 of the processing line are each assigned focus elements 120 with different effective distances deff. In particular, the respective distances deff of the focus elements 120 assigned to a specific section 140 are then at least approximately constant.

[0156] In particular, an effective distance component dz,eff of the effective distance deff oriented parallel to the thickness direction 134 of the material 102 and / or perpendicular to the feed direction 126 is different from zero for all focus elements 120 and / or for all pairs of mutually adjacent focus elements 120.

[0157] In particular, all adjacent focus elements 120 are spaced apart in the thickness direction 134 by an effective distance component dz,eff that is non-zero.

[0158] Furthermore, the machining line 136 and / or the respective sections 140 of the machining line 136 are assigned a specific angle of attack α and / or angle of attack range, which the machining line 136 or the respective section 140 encloses with the first outer side 130 of the workpiece 104. In the case of an angle of attack between 1° and 89°, the adjacent focus elements 120 each have a further effective distance component dx,eff of the effective distance deff that is different from zero and is oriented perpendicular to the feed direction 126 and perpendicular to the effective distance component dz,eff.

[0159] The effective distance component dz,eff and the effective distance component dx,eff each lie in a plane oriented perpendicular to the feed direction 126.

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

[0161] By applying and / or introducing the focus elements 120 into the material 102, localized material modifications 138 are formed, which are arranged at the respective local positions xo, yo, zo of the corresponding focus elements 120 in the material 102 (Fig. 3). By appropriately selecting processing parameters, such as the respective distances d between the focus elements 120, their respective intensities I, the feed rate oriented in the feed direction 126, and the laser parameters of the input laser beam 108, the material modifications 146 can be formed, for example, as Type III modifications, which 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.

[0162] Alternatively, it is also possible, by appropriately selecting the processing parameters, to form the material modifications 146 as Type I and / or Type II modifications, which are accompanied by a heat accumulation in the material 102 and / or a change in the refractive index of the material 102. The formation of the material modifications 146 as Type I and / or Type II modifications is associated with a heat accumulation in the material 102 of the workpiece 104. In particular, to form these material modifications 146, the respective distance d between the focus elements 120 is selected to be so small that this heat accumulation occurs when the material 102 is exposed to the focus elements.

[0163] Fig. 7a shows a simulated intensity distribution of a plurality of focus elements 120, wherein the distance d for these focus elements 120 is approx.

[0164] 17.5 |jm. In the grayscale representation shown, brighter areas represent higher intensities.

[0165] Fig. 7b shows a simulated intensity distribution of a plurality of focus elements 120, where the distance d is approximately 8.0 |jm.

[0166] The laser processing of the workpiece 104 by means of the device 100 works as follows:

[0167] To carry out the laser processing, the material 102 of the workpiece 104 is subjected to the focus elements 120 and the focus elements 120 are moved in the feed direction 126 relative to the workpiece 104 through its material 102.

[0168] The material 102 is a material, such as a glass material, that is transparent to a wavelength of the laser beams from which the focus elements 120 are formed. In the example shown, the focus elements are formed by beam shaping the input laser beam 108.

[0169] By applying the focus elements 120 to the material 102, material modifications 138 are formed in the material 102, which are arranged along the processing line 136 in a cross-section oriented perpendicular to the feed direction 126 (Fig. 8a). In the example shown in Fig. 8a, material modifications 138 are formed continuously across the entire thickness D of the material 102.

[0170] By moving the focus elements 120 relative to the material 102 along a predetermined trajectory 142, a processing surface 144 corresponding to the processing line 136 is formed, on which the material modifications 138 are arranged. This results in a planar formation and / or arrangement of the material modifications 146 along the processing surface 144.

[0171] The trajectory 142 can generally have straight and curved sections. In the case of curved sections, the processing line 136 is rotated during laser processing in particular such that it always lies in a plane oriented perpendicular to the feed direction 126. This can be achieved, for example, by correspondingly rotating the beam splitting element 106 or by rotating the entire device 100 relative to the workpiece 104.

[0172] A distance between adjacent material modifications 138 in the feed direction 126 can be defined, for example, by setting a pulse duration of the input laser beam 108 and / or by setting the feed rate.

[0173] The material modifications 146 formed along the processing line 136 result, in particular, in a reduction in the strength of the material 102. This allows the material 102 to be separated into two different workpiece segments 146a, 146b after the material modifications 146 have been formed on the processing surface 144, for example by applying a mechanical force (Fig. 8b).

[0174] In the example shown, the workpiece segment 146a is a workpiece segment with a parting surface 148, which has a shape corresponding to the shape of the machining line 136. In this case, the workpiece segment 154a is a residual workpiece segment and / or a waste segment.

[0175] The material 102 of the workpiece 104 is, for example, quartz glass.

[0176] For example, to form the material modifications 138 as Type I and / or Type II modifications, a laser beam from which the focus elements 120 are formed has a wavelength of 1030 nm and a pulse duration of 1 ps. Furthermore, a numerical aperture assigned to the focusing optics 118 is 0.4, and a pulse energy assigned to a single focus element 120 is 50 to 200 nJ. To form the material modifications 138 as Type III modifications, with all other parameters remaining the same, the pulse energy assigned to a single focus element 120 is 500 to 2000 nJ.

[0177] List of reference symbols a angle of attack d distance do distance deff effective distance dx,eff effective distance component dz,eff effective distance component

[0178] D Thickness

[0179] I Intensity xo Position in x-direction yo Position in y-direction

[0180] ZO Position in z-direction

[0181] 100 device

[0182] 102 Materials

[0183] 104 Workpiece

[0184] 106 beam splitting element

[0185] 108 input laser beam

[0186] 110 Laser beam source

[0187] 112 beam cross-section

[0188] 114 Wavefront

[0189] 116 partial beams

[0190] 116a Partial beam

[0191] 116b partial beam

[0192] 118 Focusing optics

[0193] 120 focus element

[0194] 120a, b Focus element

[0195] 121 Focus distribution

[0196] 122 Beam shaping device

[0197] 124 Beam propagation direction

[0198] 126 Feed direction

[0199] 127 Feed device

[0200] 130 first outside

[0201] 132 second outer side thickness direction

[0202] processing line

[0203] crack

[0204] Material modification

[0205] Projection plane

[0206] Section a first section b second section c third section Level a first level b second level

[0207] Trajectory

[0208] gap

[0209] Machining surfacea Workpiece segmentb Workpiece segment Separation surface

Claims

Patent claims Method for laser processing a workpiece (104) comprising a transparent material (102), in which an input laser beam (108) is split into a plurality of partial beams (116) by means of a beam splitting element (106), partial beams (116) coupled out of the beam splitting element (106) are focused, wherein by focusing the partial beams (116) a plurality of focus elements (120) are formed, the material (102) of the workpiece (104) is subjected to the focus elements (120) for laser processing and the focus elements (120) are moved relative to the material (102) in a feed direction (126), characterized in that a subset of the formed focus elements (120a) is arranged in a first plane (141a) and a subset of the formed focus elements (120b) is arranged in at least one further plane (141b),wherein the first plane (141a) and the at least one further plane (141b) are spaced 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). Method according to claim 1, characterized in that the formed focus elements (120) are positioned such that, when viewing the focus elements (120) in a projection plane (139) oriented perpendicular to the feed direction (126), at least a subset of the focus elements (120) assigned to the first plane (141a) and the focus elements (120) assigned to the at least one further plane (141b) are arranged at different spatial positions (xo, yo, zo) in the projection plane (139). Method according to claim 1 or 2, characterized in that the formed focus elements (120) are positioned such thatthat when viewing the focus elements (120) in a projection plane (139) oriented perpendicular to the feed direction (126), at least a subset of the first plane (141a) assigned, Focus elements (120a) and the focus elements (120b) assigned to at least one further plane (141b) are positioned in the projection plane (139) along a processing line (136), wherein material modifications (138) are formed in the material (102) by relative movement of the focus elements (120) with respect to the material (102) in the feed direction (126), said material modifications being arranged along the processing line (136). Method according to claim 3, characterized in that material modifications (138) are formed in the material (102) by the relative movement of the focus elements (120) along a processing surface (144) corresponding to the processing line (136), wherein in particular the material modifications (138) are arranged along the processing line (136) in a cross-section through the processing surface (144) oriented perpendicular to the feed direction (126).Method according to claim 3 or 4, characterized in that adjacent focus elements (120) arranged along the processing line (136) have an effective distance (deff) of at least 2 pm and / or at most 200 pm in the projection plane (139). Method according to one of claims 3 to 5, characterized in that an effective distance (deff) between adjacent focus elements (120) arranged along the processing line (136) in the projection plane (139) and / or an intensity (I) of the focus elements (120) is selected such that by applying the focus elements (120) to the material (102) and by relative movement of the focus elements (120) with respect to the material (102) in the feed direction (126), material modifications (138) are formed in the material (102), which enable a separation of the material (102).Method according to one of claims 3 to 6, characterized in that at least a subset of adjacent focus elements (120) which are arranged along the processing line (136) are in the. Projection plane (139) are spaced from one another at least approximately by an equal effective distance (deff). Method according to one of claims 3 to 7, characterized in that at least a subset of adjacent focus elements (120) arranged along the processing line (136) are spaced from one another by an effective distance (deff), wherein the effective distance (deff) has an effective distance component (dz,eff) that is different from zero and is oriented parallel to a thickness direction (134) of the workpiece (104), and / or has a further effective distance component (dx,eff) that is different from zero and is oriented perpendicular to the thickness direction (134) of the workpiece (104).Method according to one of claims 3 to 8, characterized in that an angle of incidence (o) between the processing line (136) and an outer side (130) of the workpiece (104), through which the focus elements (120) for laser processing are coupled into the material (102) of the workpiece (104), is at least in sections at least 1° and / or at most 90° and in particular at most 89°. Method according to one of the preceding claims, characterized in that the formed focus elements (120) are positioned such that, when viewing the focus elements (120) in a projection plane (139) oriented perpendicular to the feed direction (126), gaps (143) are formed between mutually adjacent focus elements (120a) which are assigned to the first plane (141a), wherein focus elements (120b) assigned to the at least one further plane (141b) are present and are arranged in the gaps (143).Method according to one of the preceding claims, characterized in that a distance (d) between mutually adjacent focus elements (120a) which are assigned to the first plane (141a) is at least 3 pm and / or at most 70 pm and in particular at least 5 pm and / or at most 10 pm, and / or that a distance (d). of mutually adjacent focus elements (120b) assigned to the at least one further plane (141b) is at least 3 |jm and / or at most 70 |jm and in particular at least 5 |jm and / or at most 10 |jm. Method according to one of the preceding claims, characterized in that a division of the input laser beam (108) by means of the beam splitting element (106) takes place by phase imposition on a beam cross-section (112) of the input laser beam (108) or comprises a phase imposition on a beam cross-section (112) of the input laser beam (108).Method according to one of the preceding claims, characterized in that by applying the focus elements (120) to the material (102) of the workpiece (104), material modifications (138) are formed in the material (102), wherein the material modifications (138) are accompanied by crack formation in the material (102), and / or wherein the material modifications (120) are type III material modifications. Method according to one of the preceding claims, characterized in that by applying the focus elements (120) to the material (102) of the workpiece (104), material modifications (138) are formed in the material (102), wherein the material modifications (138) are accompanied by a change in a refractive index of the material (102), and / or wherein the material modifications (138) are type I material modifications and / or type II material modifications.Device for laser processing a workpiece (104) which has a transparent material (102), comprising a beam splitting element (106) for splitting an input laser beam (108) into a plurality of partial beams (116), a focusing optics (118) for focusing partial beams (116) coupled out from the beam splitting element (106), wherein the focusing of the partial beams (116) results in a plurality of focus elements (120). Laser processing of the workpiece (104), and a feed device (127) for carrying out 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 splitting element (106) and the focusing optics (118) are designed to arrange the focus elements (120) such that a subset of the formed focus elements (120a) is arranged in a first plane (141a) and a subset of the formed focus elements (120b) is 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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