Method and device for laser processing a workpiece - Patent Application 20070122997

Abstract

The present invention provides a method for laser processing a workpiece (104) having a transparent material (102), comprising: splitting an input laser beam (108) into multiple sub-beams (116) by a beam splitting element (106); focusing the combined output sub-beams (116) from the beam splitting element (106); forming multiple focusing elements (120) by focusing the sub-beams (116); applying the focusing elements (120) to the material (102) of the workpiece (104) for laser processing; and 0) is moved in a feed direction (126) relative to the material (102), the method being characterized in that a portion of the formed focal elements (120a) is arranged in a first plane (141a) and a portion of the formed focal elements (120b) is arranged in at least one other plane (141b), the first plane (141a) and the at least one other plane (141b) are spaced apart parallel to the feed direction (126), and the first plane (141a) and the at least one other 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, in which an input laser beam is split into multiple sub-beams by a beam splitting element, the sub-beams combined out of the beam splitting element are focused, multiple focusing elements are formed by focusing the sub-beams, the focusing elements are applied to the workpiece material for laser processing, and the focusing elements are moved in a feed direction relative to the material.

[0002] The present invention further relates to a device 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 unit for focusing the sub-beams combined and output from the beam splitting element, wherein a plurality of focusing elements for laser processing of the workpiece are formed by focusing the sub-beams; and a feeding device for performing relative movement of the focusing elements with respect to the material of the workpiece in a feeding direction.

[0003] WO 2022 / 167254(A1) and WO 2022 / 167257(A1) each disclose a method and a device for laser processing of a transparent workpiece, in which multiple focusing elements are applied to the workpiece for laser processing.

[0004] DE 102014116958 A1 discloses a diffractive optical beam shaping element for applying a phase profile to a laser beam provided for laser processing of a material that is substantially transparent to the laser beam using a phase mask, the diffractive optical beam shaping element being formed to apply a plurality of beam-shaping phase profiles to a laser beam incident on the phase mask, at least one of the plurality of beam-shaping phase profiles being associated with a virtual optical image that can be imaged onto at least one elongated focal zone to form a modification in the material to be processed.

[0005] A method for cutting transparent materials using an elongated focal zone of a laser beam is known from EP 3597353 A1.

[0006] A method for cutting, in particular beveling, transparent materials is known from JP 2020-004889 A, in which multiple focal points for laser processing of the material are generated using a spatial light modulator.

[0007] Methods for forming beveled edge regions on transparent materials using a laser beam are known from US Patent Application Publication Nos. 2020 / 0147729 (A1) and 2020 / 0361037 (A1).

[0008] A method for cutting transparent materials using multiple parallel non-diffracting laser beams is known from WO 2016 / 089799 A1. [Background technology]

[0009] The present invention is based on the object of providing a method and a device as mentioned above, by which material modifications can be formed in the material of the workpiece, allowing the cutting of the material with improved quality, in particular with reduced roughness of the cutting surface.

[0010] Summary of the Invention This object is achieved according to the present invention in the method mentioned at the outset, in which a partial quantity of the formed focal elements is arranged in a first plane, a partial quantity of the formed focal elements is arranged in at least one further plane, the first plane and the at least one further plane are spaced apart parallel to the feed direction, and the first plane and the at least one further plane are oriented perpendicular to the feed direction.

[0011] During laser processing of a workpiece by the method according to the invention, material modifications are produced in the material of the workpiece, which in particular allow cutting of the material.

[0012] By arranging the focal elements in both the first plane and at least one further plane, the effective distance of the focal elements oriented perpendicular to the feed direction can be reduced. This allows adjacent material modifications to be created in the workpiece material with a particularly small distance between them, thus increasing the density of the material modifications formed in the material. This improves the cuttability of the material. Furthermore, the quality of the cut surface resulting from cutting the material can be increased; the cut surface can be specifically designed with reduced roughness and / or increased smoothness. This results in increased edge stability of the workpiece material at the cut surface after the cut is made.

[0013] If the actual distance between adjacent focal elements becomes too small, undesirable interference effects between adjacent focal elements may result, for example, in a beating effect in the intensity of the focal elements. This may make it difficult to control the generation of material modifications, and in particular to generate identical material modifications. In the solution according to the present invention, the focal elements for generating material modifications are arranged "offset" in the feed direction, so that the effective distance is significantly reduced when the actual distance between the focal elements is sufficiently large.

[0014] The distance between focal elements, i.e., the actual distance, is the actual distance between these focal elements in three-dimensional space. The effective distance between focal elements is the distance between the perpendicular projections of the focal elements in a projection plane oriented perpendicular to the feed direction.

[0015] The spatial location and / or position of a particular focal element should be understood specifically as being its center and / or centroid within the material. Specifically, the distances and effective distances relate to the corresponding centers of the focal elements within the material, i.e., they are center distances.

[0016] By relative movement of the focusing elements arranged in the first plane and at least one further plane with respect to the material in the feed direction, material modifications are produced in at least a portion of the material spaced apart by an effective distance.

[0017] Using the method according to the invention, material modifications can in particular be produced such that adjacent material modifications overlap within the material, which results in crack connections between adjacent material modifications and allows for particularly good cutting of the material by etching or applying heat.

[0018] A material modification is produced by applying a focal element to the material of the workpiece at a particular time, the material modification being located within the material at the location where the focal element is positioned within the material at that time.

[0019] In particular, all focal elements associated with the first plane and / or the at least one further plane are present simultaneously.

[0020] For example, two or more planes oriented perpendicular to the feed direction can be provided, in each of which a partial amount of formed focal elements is located, the intended planes being oriented parallel to one another and / or spaced apart from one another in the feed direction.

[0021] In particular, the distance between the first plane and the at least one further plane may be at least 2 μm and / or at most 200 μm, for example the distance is approximately 10 μm.

[0022] In particular, the formed focal elements can be positioned such that when the focal elements are viewed in a projection plane oriented perpendicular to the feed direction, at least a portion of the focal elements associated with the first plane and the at least one further plane are located at different spatial positions in the projection plane, which allows the effective distance between adjacent focal elements to be reduced, and accordingly the distance between adjacent formed material modifications to be reduced.

[0023] In particular, the formed focal elements can be positioned such that, when the focal elements are viewed in a projection plane oriented perpendicular to the feed direction, at least a portion of the focal elements associated with the first projection plane and the at least one further projection plane are positioned in the projection plane along a processing line, and relative movement of the focal elements with respect to the material in the feed direction produces a material modification in the material that is disposed along the processing line. In particular, the edge shape and / or cross-sectional shape of the cut surface resulting from cutting the material in the material modification can be defined by the processing line.

[0024] For example, at least one processing line has a total length of 10 μm to 10,000 μm, specifically 100 μm to 1,000 μm, specifically 400 μm to 600 μm. Workpieces having thicknesses within the above ranges can be processed, specifically cut, by this.

[0025] The material of the workpiece has a thickness of, for example, 10 μm to 10000 μm, preferably 100 μm to 1000 μm, for example approximately 500 μm.

[0026] In particular, the processing lines can be formed spatially continuous across the thickness of the workpiece material and / or across the thickness of the workpiece segment being cut from the workpiece.

[0027] The processing line does not necessarily have a spatially continuous design, but rather may have different spatially separated portions, in particular, the processing line may have interruptions in which no focal elements are located.

[0028] Specifically, a material modification along the processing surface corresponding to the processing line is generated by the relative movement of the focal element within the material. The material modification is then located along the processing line, particularly when viewed in a cross section through the processing surface oriented perpendicular to the feed direction. After the workpiece is cut with the material modification located along the processing surface, the shape and / or cross-sectional shape of the cutting surface formed during cutting specifically corresponds to the (former) shape and / or cross-sectional shape of the processing surface.

[0029] It can be advantageous if adjacent focal elements arranged along the processing line have an effective distance in the projection plane of at least 2 μm and / or at most 200 μm, which makes it possible to produce cutting surfaces of particularly high quality and / or reduced roughness.

[0030] Focal elements arranged along the processing line and / or visible in the projection plane are understood to mean focal elements associated with a first plane and at least one further plane.

[0031] Specifically, the effective distance of the focal element along the processing line corresponds at least approximately to the distance of the material modification formed on the processing surface corresponding to the processing line and positioned in a cross section through the processing surface oriented perpendicular to the feed direction.

[0032] In particular, the effective distance and / or strength of adjacent focal elements arranged along the processing line in the projection plane can be selected such that application of the focal elements to the material and relative movement of the focal elements with respect to the material in the feed direction produces a material modification in the material that enables cutting of the material.

[0033] In particular, at least a fraction of adjacent focal elements arranged along the processing line can be at least approximately spaced apart in the projection plane with the same effective distance from each other.

[0034] It may be advantageous for at least a portion of adjacent focal elements arranged along the processing line to be spaced apart by an effective distance, the effective distance having a non-zero effective distance component oriented parallel to the thickness direction of the workpiece and / or having a further non-zero effective distance component oriented perpendicular to the thickness direction of the workpiece, thereby enabling, for example, perpendicular cuts to be produced on the workpiece or for the workpiece to be chamfered at a particular angle.

[0035] The thickness direction of the workpiece should be understood to mean, specifically, a direction oriented transversely, specifically perpendicularly, to the outer side of the workpiece through which the focal element and / or the laser beam for forming the focal element is coupled into the material.

[0036] The thickness direction is specifically oriented transversely or perpendicular to the beam propagation direction of the laser beam from which the focal element is formed.

[0037] Specifically, at least one partial amount of mutually adjacent focal elements arranged along the processing line can be spaced apart by an effective distance having an effective distance component different from zero that is oriented parallel to the beam propagation direction of the laser beam along which the focal elements are formed, and / or at least one partial amount of mutually adjacent focal elements arranged along the processing line can be spaced apart by an effective distance having an effective distance component different from zero that is oriented perpendicular to the beam propagation direction of the laser beam along which the focal elements are formed.

[0038] For the same reason, it may be advantageous if the angle of attack between the processing line and the outer side of the workpiece, through which the focal element for laser processing is bonded to the material of the workpiece, is at least in some parts at least 1° and / or at most 90°, in particular at most 89°. Depending on the choice of the angle of attack, for example, a perpendicular cut can be performed on the workpiece or the workpiece can be chamfered at a certain angle.

[0039] A processing line having at least in some places a particular angle of attack or range of angles of attack is to be understood in particular to mean that the processing line has at least one portion with this angle of attack or range of angles of attack.

[0040] In particular, the angle of attack may 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°.

[0041] In particular, the angle of attack of the processing line may be constant at least in places and / or the processing line may have multiple portions with different angles of attack.

[0042] In particular, it is possible for the processing line to be at least partially straight and / or for the processing line to be at least partially curved.

[0043] By configuring the processing line as a curve, for example, rounded segments can be cut out of the workpiece, for example, this can create rounded edges.

[0044] When the machining line is configured as a curve, the machining line is associated with a particular range of angles of attack that the machining line has relative to the outer side of the workpiece, for example.

[0045] The formed focal elements may advantageously be positioned such that, when the focal elements are viewed in a projection plane oriented perpendicular to the feed direction, a gap is formed between mutually adjacent focal elements associated with a first plane and there is a focal element located within the gap associated with at least one further plane, which makes it possible to reduce the effective distance between adjacent focal elements and / or to increase the density of the material modification produced in the material.

[0046] In particular, the distance between adjacent focal elements associated with the first plane may be at least 3 μm and / or at most 70 μm, in particular at least 5 μm and / or at most 10 μm.

[0047] In particular, the distance between adjacent focal elements associated with at least one further plane may be at least 3 μm and / or at most 70 μm, in particular at least 5 μm and / or at most 10 μm.

[0048] In particular, the splitting of the input laser beam by the beam splitting element can be performed by or include phase imprinting into the beam cross section of the input laser beam. The focusing elements can thereby be formed, for example, as copies of each other. In particular, the focusing elements can thereby be introduced into the material of the workpiece at different positions and / or at different intervals in a technically simple manner.

[0049] Splitting of the input laser beam can only be achieved by phase imprinting onto the beam cross section of the input laser beam.

[0050] Specifically, the phase imprinting is performed in the transverse direction of the input laser beam, which lies in a plane oriented perpendicular to the beam propagation direction of the input laser beam.

[0051] Alternatively or additionally, the splitting of the input laser beam by the beam splitting elements can be performed by or include polarizing beam splitting, in which case adjacent focusing elements can be formed, for example, with different polarization states, which makes it possible to prevent interference between adjacent focusing elements, but means that these focusing elements can be arranged at a particularly small distance from each other.

[0052] In principle, splitting of an input laser beam can be done by both means: by phase imprinting and by polarization beam splitting.

[0053] In particular, the input laser beam and / or the laser beam from which the focusing element is formed is a pulsed laser beam, in particular an ultrashort pulse laser beam, and by applying the focusing element to the material, in particular a laser pulse, in particular an ultrashort laser pulse, is thereby introduced into the material.

[0054] The material modifications introduced into transparent materials by ultrashort laser pulses are subdivided into three different classes: Type I is an isotropic refractive index change, Type II is a birefringent refractive index change, and Type III is a void or cavity (see K. Itoh et al. "Ultrafast Processes for Bulk Modification of Transparent Materials" MRS Bulletin, vol. 31, p. 620 (2006)). The type of material modification produced by a particular focusing element depends on the laser parameters of the laser beam that the corresponding focusing element is formed with, 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, such as the material's electronic structure and thermal expansion coefficient, as well as the numerical aperture (NA) used to focus the laser beam onto the corresponding focusing element.

[0055] Type I isotropic refractive index changes are caused by spatially limited melting and rapid resolidification of transparent materials by laser pulses. For example, fused silica has a higher material density and refractive index when cooled rapidly from a higher temperature. Thus, if a material within the volume detected by the focal element is melted and then rapidly cooled, the fused silica will have a higher refractive index in the region of material modification than in the unmodified region.

[0056] Type II birefringence can occur, for example, due to interference between an ultrashort laser pulse and the electric field of the plasma generated by the laser pulse. This interference results in a periodic modulation of the electron plasma density, which, upon solidification, causes birefringence, i.e., a directionally dependent refractive index, in the transparent material. Type II modification can also involve, for example, the formation of nanolattices.

[0057] In particular, type III modified voids (cavities) can be produced using high laser pulse energy. The formation of voids in this case is due to the explosive expansion of highly excited vaporized material from the focal volume into the surrounding material. This process is also called microexplosion. Because this expansion occurs within the mass of the material, the microexplosion leaves behind a less dense or hollow core (void) or a microscopic defect in the submicrometer or atomic range, surrounded by a compressed material envelope. The compression at the shock front of the microexplosion creates stress in the transparent material, which typically causes or promotes spontaneous crack formation.

[0058] Thus, for the introduction of type III modifications, in either case there is a low density or hollow core or a defect. As an example, in the case of type III modifications in sapphire, regions of lower density, rather than voids, are created by microexplosion.

[0059] Specifically, the formation of voids may be accompanied by type I and type II modifications. As an example, type I and type II modifications can occur in low-stress regions around the introduced laser pulse. The formation of type I and type II modifications cannot be completely prevented or avoided when introducing type III modifications. Therefore, it is unlikely that a "pure" type III modification will be found.

[0060] It may be advantageous if application of the focal element to the material of the workpiece produces a material modification in the material, where the material modification involves the formation of cracks in the material and / or the material modification is a Type III material modification, particularly where these material modifications enable the material to be cut.

[0061] It may be preferred if the application of the focusing element to the workpiece material creates a material modification in the material, the material modification involving a change in the refractive index of the material and / or the material modification being a Type I and / or Type II material modification, in particular capable of cutting the material.

[0062] Specifically, the material of the workpiece is cuttable or severable after laser processing, specifically, the material is cuttable or severable within the processing surface where the laser processing has produced a material modification.

[0063] Specifically, the material of the workpiece can be cut or can be cut by applying heat and / or mechanical tension and / or by etching with at least one wet chemical solution. For example, etching is performed in an ultrasonically assisted etching bath. The application of heat can be achieved, for example, by a CO2 laser.

[0064] According to the present invention, in the device mentioned at the beginning, the beam splitting element and the focusing optical unit are configured to arrange the focusing elements so that a partial amount of the formed focusing elements is arranged in a first plane and a partial amount of the formed focusing elements is arranged in at least one other plane, the first plane and the at least one other plane being spaced apart parallel to the feed direction, and the first plane and the at least one other plane being oriented perpendicular to the feed direction.

[0065] 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 described in connection with the method according to the invention.

[0066] In particular, the method according to the invention can be implemented using the device according to the invention, or the method according to the invention is carried out using the device according to the invention.

[0067] It may be advantageous if the beam splitting element is formed as or comprises a 3D beam splitting element, in which case the splitting of the input laser beam can be performed by phase imprinting on the beam cross section of the input laser beam, in particular only by phase imprinting on the beam cross section of the input laser beam.

[0068] It may be preferred if the beam splitting element is formed as or comprises a polarizing beam splitting element.

[0069] For example, a beam splitting element may include multiple components and / or functions. It is possible for a beam splitting element to include both a 3D beam splitting element and a polarizing beam splitting element.

[0070] In particular, the device comprises a laser beam source for providing an input laser beam, the input laser beam being in particular a pulsed laser beam and / or an ultrashort pulsed laser beam.

[0071] In particular, a transparent material is understood to mean a material that transmits at least 70%, in particular at least 80%, in particular at least 90% of the laser energy of the input laser beam and / or the laser energy of the laser beam from which the focal element is formed.

[0072] Specifically, a focal element is understood as a radiation region having a specific spatial extension and intensity distribution. To determine the spatial dimensions of a specific focal element, such as the diameter of the focal element, only intensity values ​​of the intensity distribution that exceed a specific intensity threshold are taken into account. In this regard, the intensity threshold is selected, for example, so that values ​​below this intensity threshold have such low intensities that they are no longer relevant for interacting with the material in order to generate material modifications. For example, the intensity threshold is 50% of the overall intensity maximum of the focal element.

[0073] Specifically, a particular focal element is associated with a spatial region of interaction that the focal element interacts with when introduced into the material of the workpiece.

[0074] Specifically, a focusing element introduced into a material interacts with the material through nonlinear absorption, and specifically, material modifications are produced in the material due to the nonlinear absorption by the focusing element.

[0075] In particular, a focal element according to the previous definition may have a maximum spatial extension 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 extension of the region of interaction with the material of the workpiece associated with a given focal element is at least 0.5 μm and / or at most 30 μm, preferably at least 2 μm and / or at most 10 μm.

[0076] The maximum spatial extension of a given focal element is understood to mean in particular the maximum spatial extension of the focal element in any spatial direction.

[0077] In particular, the maximum spatial extension of the focusing element is less than 20%, preferably less than 10%, particularly preferably less than 5% of the thickness of the material.

[0078] In particular, the focusing elements have a diffractive beam profile. In particular, the focusing elements are designed to be diffraction limited. For example, certain focusing elements have a Gaussian shape and / or a Gaussian intensity profile.

[0079] In particular, the input laser beam and / or the laser beam from which the focusing element is formed has a diffractive beam profile and / or a Gaussian beam profile.

[0080] For example, the wavelength of the input laser beam and / or the laser beam from which the focusing element is formed is at least 300 nm and / or at most 1500 nm, for example the wavelength is 515 nm or 1030 nm.

[0081] Specifically, the input laser beam and / or the laser beam formed by the focusing element has an average power of at least 1 W to 1 kW. For example, the laser beam includes pulses having a pulse energy of at least 10 μJ and / or at most 50 mJ. The laser beam can include individual pulses or bursts, with bursts having 2 to 20 sub-pulses and specifically a time interval of approximately 20 ns.

[0082] The phrase "at least a partial amount of focal elements" can mean either a partial amount of focal elements or the total amount of focal elements, i.e., all focal elements.

[0083] Specifically, the statement "at least approximately" or "approximately" should generally be understood to mean a deviation of at most 10%. Unless otherwise specified, the statement "at least approximately" or "approximately" should be understood to mean specifically that the actual value and / or distance and / or angle deviates from the ideal value and / or distance and / or angle by 10% or less.

[0084] The following description of preferred embodiments serves to explain the invention in more detail with reference to the drawings. [Brief explanation of the drawings]

[0085] [Figure 1] 1 shows a schematic diagram of one exemplary embodiment of a device for laser processing a workpiece. [Figure 2] 1 shows a schematic cross-sectional view of a portion of a workpiece material where multiple focusing elements are applied to the material for laser processing. [Figure 3] 1 shows a schematic cross-sectional view of a portion of a workpiece in which a focal element has been applied to the workpiece to produce a material modification involving crack formation within the material. [Figure 4]1 shows an arrangement of focusing elements designed for laser processing of a workpiece, with the projection of the focusing elements shown on a projection plane oriented perpendicular to the feed direction. [Figure 5a] 1 shows the arrangement of focusing elements designed for laser processing of a workpiece in a cross section oriented parallel to the feed direction and thickness direction of the workpiece. [Figure 5b] 5b shows the focusing element according to FIG. 5a in a cross section oriented parallel to the feed direction and perpendicular to the thickness direction of the workpiece. [Figure 6] 5a and 5b show a focusing element in perspective view. [Figure 7a] 1 shows a cross-sectional view of a simulated intensity distribution of a focal element for laser processing of a workpiece, with adjacent focal elements each spaced apart by a distance of approximately 17.5 μm. [Figure 7b] 1 shows a cross-sectional view of a simulated intensity distribution of a focal element for laser processing of a workpiece, with adjacent focal elements each spaced apart by a distance of approximately 8.0 μm. [Figure 8a] 1 shows a schematic perspective view of a workpiece having a material modification created thereon, the material modification extending along a processing line and / or processing surface. [Figure 8b] 8b shows a schematic perspective view of two workpiece segments, which have been formed by cutting the workpiece according to FIG. 8a along processing lines and / or processing surfaces.

[0086] Elements that are the same or have equivalent functions are given the same reference numerals in all figures.

[0087] One exemplary embodiment of a device for laser processing a workpiece is shown in Figure 1, where it is designated 100. Localized material modifications, such as defects in the sub-micrometer or atomic range that result in weakening of the material, can be created in the material 102 of the workpiece 104 using the device 100. These material modifications can cut the workpiece 104, for example, workpiece segments can be cut from the workpiece 104.

[0088] Specifically, material modifications can be introduced into material 102 at an angle of attack using device 100, whereby edge regions of workpiece 104 can be chamfered or beveled by cutting workpiece segments from workpiece 104.

[0089] The device comprises a beam splitting element 106 into which an input, particularly collimated, laser beam 108 is coupled. This input laser beam 108 is provided, for example, by a laser beam source 110. In particular, the input laser beam 108 is a pulsed laser beam and / or an ultrashort pulsed laser beam.

[0090] The laser beam source 110 may comprise a hollow core fiber (not shown) from which emerges a laser beam formed by the laser beam source, which is then collimated by a collimation optical unit (not shown) of the laser beam source 110, for example, to form a collimated input laser beam 108.

[0091] In particular, the input laser beam 108 should be understood to mean a beam bundle that includes a plurality of parallel beams. The input laser beam 108 has a transverse beam cross section 112 and / or a transverse beam expansion where the input laser beam 108 enters the beam splitting element 106. The input laser beam 108 entering the beam splitting element 106 has an at least approximately flat wavefront 114.

[0092] An input laser beam 108 is split into multiple sub-beams 116 and / or sub-beam bundles by beam splitting element 106. In the embodiment shown in Figure 1, two different sub-beams 116a and 116b are shown.

[0093] In particular, the beam splitting element 106 takes the form of a far-field beam forming element, and the sub-beams 116 or bundles of sub-beams coupled out of the beam splitting element 106 in particular have diverging beam profiles and / or propagate like spherical waves.

[0094] To focus the sub-beams 116 coupled out of the beam splitting element 106, the device 100 includes a focusing optical unit 118 into which the sub-beams 116 are coupled. The focusing optical unit 118 has, for example, one or more lens elements. For example, the focusing optical unit 118 is formed as a microscope objective.

[0095] For example, the focusing optical unit 118 has a focal length of 5 mm to 50 mm.

[0096] The beam splitting element 106 is specifically positioned at least approximately at the back focal plane of the focusing optical unit 118 .

[0097] In particular, the different sub-beams 116 are incident on the focusing optical unit 118 with a positional and / or angular offset. These sub-beams 116 are focused by the focusing optical unit 118 such that multiple focusing elements 120 are formed, each located at a different spatial position. In principle, mutually adjacent focusing elements can partially spatially overlap.

[0098] For example, one or more sub-beams 116 and / or sub-beam bundles are each associated with a given focusing element 120. For example, a focusing element 120 is formed by focusing one or more sub-beams 116 and / or sub-beam bundles.

[0099] The focal elements 120 should be understood in particular as focused radiation areas such as focal spots and / or focal points. In particular, the focal elements 120 each have a specific geometric shape and / or a specific intensity profile, where the geometric shape should be understood as, for example, the spatial shape and / or spatial extension of the focal elements 120.

[0100] The geometric shape and / or intensity profile of a particular focal element 120 is hereinafter referred to as the focal distribution 121 of the focal element 120. The focal distribution 121 is a property of the focal elements 120 and describes their shape and / or intensity profile. Specifically, multiple or all of the formed focal elements 120 have the same focal distribution.

[0101] The focal distribution of the formed focal element 120 is defined by the input laser beam 108, the division of which using the beam splitting element 106 forms the focal element 120. If the input laser beam 108 is focused before being coupled into the beam splitting element 106, this will result in the formation of a single focal element having the focal distribution associated with the input laser beam 108.

[0102] For example, the input laser beam 108 has a Gaussian beam profile, for example, when provided by the laser beam source 110. Focusing the input laser beam 108 will, in this case, result in the formation of focal elements having a focal distribution with a Gaussian shape and / or a Gaussian intensity profile.

[0103] Alternatively, a Bessel-like beam profile can be associated with the input laser beam 108, for example, such that focusing the input laser beam 108 results in the formation of focal elements having a Bessel-like shape and / or a focal distribution with a Bessel-like intensity profile.

[0104] The focal distribution of the input laser beam 108 is related to the sub-beams 116 and / or sub-beam bundles formed by splitting the input laser beam 108 using the beam splitting element 106 such that by focusing the sub-beams 116, a focal element 120 is formed having this focal distribution and / or a focal distribution based on this focal distribution.

[0105] 1, the input laser beam 108 has a Gaussian beam profile, i.e., a focal distribution having a Gaussian shape and / or a Gaussian intensity profile is associated with the input laser beam 108. In this case, the focusing elements 120 each have a focal distribution 121, e.g., having this Gaussian shape and / or this Gaussian intensity profile, or having a shape and / or intensity profile based on this Gaussian shape and / or this Gaussian intensity profile (see also Figures 5a and 5b).

[0106] For example, if a Bessel-shaped beam profile is associated with the input laser beam 108, then the focal elements 120 formed for laser processing of the workpiece 104 each have a focal distribution 121 that has this Bessel-shaped beam profile or a beam profile based on this Bessel-shaped profile. Thus, the focal elements 120 can each be formed with a focal distribution that has, for example, an elongated shape and / or an elongated intensity profile.

[0107] The device 100 can include a beam former 122 for beam shaping of the input laser beam 108 (shown in FIG. 1 ), for example, the beam former 122 being located upstream of the beam splitting element 106 and / or between the laser beam source 110 and the beam splitting element 106 with respect to a beam propagation direction 124 of the input laser beam 108.

[0108] Beam propagation direction is understood to mean in particular the main beam propagation direction and / or the average propagation direction of the laser beam and / or beam bundle, which in particular corresponds to the direction of the Poynting vector associated with the laser beam or beam bundle.

[0109] The beam former 122 allows a particular beam profile to be associated with the input laser beam 108 , which particular beam profile defines the focal distribution 121 of the focusing element 120 .

[0110] The beam former 122 can be configured to form, for example, a laser beam having a Gaussian beam profile into a laser beam having a quasi-non-diffracting beam profile and / or a Bessel-like beam profile, for which purpose the beam former 122 can be, for example, or include, an axicon element.

[0111] The input laser beam 108 coupled into the beam splitting element 106 has a quasi-non-diffracting and / or Bessel-like beam profile, in which case the focusing element 120 also has this quasi-non-diffracting and / or Bessel-like beam profile or a beam profile based on this beam profile.

[0112] For the definition and implementation of quasi-non-diffracting beams and / or Bessel-like beams, please refer to the following books: "Structured Light Fields: Applications in Optical Trapping, Manipulation and Organization", M. Wordemann, Springer Science & Business Media (2012), ISBN 978-3-642-29322-1, and the scientific publications "Bessel-like optical beams with arbitrary trajectories", I. Chremmos et al., Optics Letters, Vol. 37, No. 23, December 1, 2012, and "Generalized axicon-based generation of nondiffracting beams", K. Chen et al., arXiv:1911.03103v1 [physics.optics], November 8, 2019.

[0113] The focusing elements 120 are each designed to be identical to one another, specifically by beam splitting using the beam splitting element 106, and / or are each designed as copies of one another.

[0114] A particular local location x0, y0, z0 is associated with each formed focal element 120 at which the focal element 120 is positioned relative to the material 102 of the workpiece 104 (FIG. 2). For example, the spatial location of a focal element 120 should be understood to mean the location of its spatial center and / or center of gravity.

[0115] Furthermore, a particular intensity I is specifically associated with each of the formed focal elements 120. The spatial position x, y, z and specifically the intensity I of the focal elements 120 can also be adjusted using the beam splitting element 106.

[0116] Specifically, multiple or all focal elements 120 formed for laser processing of workpiece 104 have the same intensity I. However, multiple focal elements 120 formed may have different intensities I.

[0117] Specifically, the beam splitting element 106 allows the distance d and / or spatial offset between adjacent focusing elements 120 to be adjusted component by component in three spatial directions and / or spatial dimensions (x, y, and z directions in the example shown in FIG. 1).

[0118] The beam splitting element 106 preferably takes the form of or includes a 3D beam splitting element, whereby the focusing elements 120 can be formed, for example, so that they are each identical to one another and / or so that they each constitute a copy of one another.

[0119] 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:2012.10119v1 [physics.optics], December 18, 2020, the entire contents of which are expressly incorporated by reference.

[0120] To perform beam splitting, in one embodiment of the beam splitting element 106, for example, where the beam splitting element 106 is embodied as a 3D beam splitting element, a defined transverse phase distribution is imprinted on the transverse beam cross section 112 of the input laser beam 108. The transverse beam cross section or transverse phase distribution should be understood to mean specifically the beam cross section or phase distribution in a plane oriented transversely, specifically perpendicular to the beam propagation direction 124 of the input laser beam 108.

[0121] The focal element 120 is formed by the interference of the focused sub-beams 116, which may result in, for example, constructive interference, destructive interference, or intermediate cases such as partially constructive interference or partially destructive interference.

[0122] To form the focal elements 120 at positions x0, y0, z0 and / or with distances d, the phase distribution imprinted by the beam splitting element 106 has specific optical grating components and / or optical lens components for each focal element 120.

[0123] Thanks to the optical grating components, after focusing of the sub-beams 116, a corresponding position offset of the formed focusing elements 120 is generated in a first spatial direction and / or a second spatial direction, e.g., in the x-direction and / or y-direction. Thanks to the optical lens components, the sub-beams 116 or sub-beam bundles are incident on the focusing optical unit 118 at different angles or with different convergences or divergences, which results in positions that are offset in a third spatial direction, e.g., in the z-direction, after focusing.

[0124] The intensity I of each focal element 120 is determined by the phase positions of the focused sub-beams 116 relative to one another. These phase positions can be defined by the optical grating and optical lens components mentioned above, and can be selected relative to one another when designing the beamsplitting element 106 so that each focal element 120 has a desired intensity.

[0125] Alternatively or additionally, the beam splitting element 106 can be formed as or include a polarizing beam splitting element, in which case polarizing beam splitting of the input laser beam 108 into beams each having one of at least two different polarization states is performed using the beam splitting element 106.

[0126] In particular, the aforementioned polarization states should be understood to mean linear polarization states, e.g., two different polarization states are provided and / or polarization states that are oriented perpendicular to each other are provided.

[0127] Specifically, 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).

[0128] For polarization beam splitting, the beam splitting element 106 may include, for example, a birefringent lens element and / or a birefringent wedge element, for example, made from or including quartz.

[0129] With regard to the operating mode and design of the beam splitting element 106 as a polarizing beam splitting element, reference is made to German Patent Application No. 1020202077150 (filing date: June 22, 2020) and German Patent Application Publication No. 102019217577 (A1) in the name of the same applicant.

[0130] In particular, the sub-beams 116 can be formed with different polarization states by polarization beam splitting. By focusing these sub-beams 116 by a focusing optical unit 118, the focusing elements 120 can be formed from beams with a specific polarization state in each case. Thereby, the focusing elements 120 can each be associated with and / or implemented with a specific polarization state.

[0131] Specifically, the focusing elements 120 can be arranged and formed by polarization beam splitting by the beam splitting element 106 such that adjacent focusing elements 120 each have a different polarization state.

[0132] For laser processing of the workpiece 104, the focal element 120 is introduced into the material 102 of the workpiece 104 and moved relative to the material 102 in a feed direction 126, specifically at a particular feed rate in the feed direction 126. In the illustrated embodiment, the feed direction 126 corresponds to the y-direction.

[0133] To effectuate the relative movement of focal element 120 with respect to material 102, device 100 includes a feeder 127 (shown in FIG. 1 ). Feeder 127 is configured to move focal element 120 through material 102 at a feed rate defined in feed direction 126. For example, the feeder can be realized by a workpiece holder configured to move workpiece 104 disposed thereon relative to focal element 120.

[0134] Coupling of the focusing element 120 into the material 102 for laser processing of the workpiece 104 is performed, for example, through a first outer side 130 of the workpiece 104 .

[0135] For example, the workpiece 104 may be plate-shaped and / or panel-shaped and / or disk-shaped. The second outer side 132 of the workpiece 104 may be spaced apart from the first outer side 130 in a thickness direction 134 and / or a depth direction of the workpiece 104, for example.

[0136] The material 102 of the workpiece 104 has, for example, an at least approximately constant thickness D in the thickness direction 134. The thickness D is, for example, 500 μm.

[0137] The feed direction 126 is oriented transversely, specifically perpendicularly, to the beam propagation direction 124 and / or the thickness direction 134 of the workpiece 104 .

[0138] The formed focal element 120 is preferably arranged so as to be positioned in a projection in a projection plane 139 that is oriented transversely, specifically perpendicularly, to the feed direction 126 along a defined processing line 136 (see FIGS. 2 and 4 ). Said projection is specifically understood to mean an orthogonal projection of the focal element 120 in the projection plane.

[0139] The processing line 136 corresponds, at least in part, to the target machined shape along which the laser processing of the material 102, and specifically the subsequent cutting of the material 102, will be performed.

[0140] The focusing element 120 has an effective distance d eff The focal elements 130 are spaced apart from one another by an effective distance d eff and intensity I are selected such that by applying focal element 120 to material 102 and moving focal element 120 through material 102, a material modification 138 is produced (FIG. 3), enabling cutting of the material along this processing line 136 and / or along a processing surface corresponding to this processing line 136.

[0141] Specifically, the processing line 136 may extend between the first outer side 130 and the second outer side 132, and specifically may extend continuously and / or without interruption between the first outer side 130 and the second outer side 132 of the workpiece 104.

[0142] 2, the process line 136 has a first portion 140a, a second portion 140b, and a third portion 140c, where the second portion 140b is adjacent to the first portion 140a and the third portion 140c is adjacent to the second portion 140b in the thickness direction 134.

[0143] The processing lines 136 are not necessarily designed to be regular and / or distinct. For example, the processing lines 136 can have irregularities. The processing lines 136 can have interruptions and / or gaps where the focal elements 120 are not located.

[0144] The processing line 136 and / or the different portions 140 of the processing line 136 may be formed, for example, as straight or curved lines.

[0145] Preferably, two or more spaced apart planes 141 are provided, in each of which a different portion of the formed focal element 120 is arranged, the planes 141 being spaced apart parallel to the feed direction 126. For example, the planes 141 are each oriented parallel to the projection plane 139 and / or transversely, in particular perpendicularly, to the feed direction 126.

[0146] 5a, 5b, and 6, the formed partial amount of focal elements 120 are positioned in a first plane 141a and a further plane, referred to in the illustrated exemplary embodiment as a second plane 141b. The first plane 141a and the second plane 141b are, for example, spaced apart from each other and oriented parallel to each other in the feed direction 126. The focal elements 120 associated with the first plane 141a are hereinafter referred to as focal elements 120a, and the focal elements 120 associated with the second plane 141b are hereinafter referred to as focal elements 120b. In FIG. 4, the total amount of focal elements 120a and 120b is shown in the form of a projection of these focal elements 120a and 120b onto the projection plane 139.

[0147] Specifically, there are focal element 120a and focal element 120b, which are located at different positions x0, z0 in the projection plane 139.

[0148] The distance d0 between the first plane 141a and the second plane 141b is, for example, 5 μm to 20 μm. Typically, the distance d0 is approximately 10 μm.

[0149] The distance d already mentioned above is to be understood as essentially the actual distance between adjacent focal elements 120 in the three spatial directions x, y, z and / or spatial dimensions.

[0150] The distance d between adjacent focal elements 120 is 3 μm to 70 μm, preferably 5 μm to 10 μm. Specifically, the distance d between adjacent focal elements 120 arranged in a certain plane 141 is within the mentioned range.

[0151] Gaps 143 are formed between adjacent focal elements 120 associated with a particular plane 141, as shown in FIG. 5a using the example of focal element 120a in a first plane 141a.

[0152] The second plane 141 b specifically includes a focal element 120 b that is positioned to be in the gap 143 when viewed in the projection plane 139 .

[0153] The effective distance d of each of the focal elements 120 provided for laser processing of the workpiece 104 eff can be selected to be different for different focal elements 120 and / or different pairs of focal elements 120. However, it is also possible that the respective distances d are at least approximately the same for all focal elements 120 provided for laser processing of the workpiece 104.

[0154] For example, different effective distances d eff Each focal element 120 having a distance d eff is at least approximately constant.

[0155] Specifically, the effective distance d oriented parallel to the thickness direction 134 of the material 102 and / or perpendicular to the feed direction 126 eff The effective distance component d z,effis different from zero for all focal elements 120 and / or all pairs of mutually adjacent focal elements 120. Specifically, all adjacent focal elements 120 have a non-zero effective distance component d z,eff are spaced apart by

[0156] Additionally, the processing line 136 and / or portion 140 of the processing line 136 is associated with a particular angle of attack α and / or range of angles of attack that the processing line 136 or portion 140 forms with the first outer side 130 of the workpiece 104 .

[0157] For angles of attack between 1° and 89°, adjacent focal elements 120 are each oriented perpendicular to the feed direction 126 and have a different effective distance component d z,eff Oriented perpendicular to the effective distance d eff The further effective range component d x,eff It has.

[0158] Effective distance component d z,eff and the effective distance component d x,eff Each lies in a plane oriented perpendicular to the feed direction 126 .

[0159] In the exemplary embodiment shown, the magnitude of the angle of attack α of first portion 140a and third portion 140c is 45°, and the magnitude of the angle of attack α of second portion 140b is 90°.

[0160] By applying and / or introducing focal elements 120 into material 102, a local material modification 138 is generated in each case, located at the local location x0, y0, z0 of the corresponding focal element 120 in material 102 ( FIG. 3 ). By suitably selecting processing parameters such as the distance d between focal elements 120, their intensity I, the feed rate oriented in feed direction 126, and the laser parameters of input laser beam 108, a material modification 146 can be generated, for example, as a type III modification associated with the spontaneous formation of cracks 137 in material 102 of workpiece 104. Specifically, cracks 137 are formed between mutually adjacent material modifications 146.

[0161] Alternatively, by suitable selection of processing parameters, it is possible to produce the material modification 146 as a Type I modification and / or a Type II modification involving heat accumulation in the material 102 and / or a change in the refractive index of the material 102. The production of the material modification 146 as a Type I modification and / or a Type II modification is associated with heat accumulation in the material 102 of the workpiece 104. Specifically, to produce these material modifications 146, the distance d between the focal elements 120 is selected to be small so that this heat accumulation occurs when the focal elements are applied to the material 102.

[0162] 7a shows the simulated intensity distribution of multiple focal elements 120, with the distance d being approximately 17.5 μm for these focal elements 120. In the greyscale value representation shown, lighter areas represent higher intensities.

[0163] FIG. 7b shows the simulated intensity distribution of multiple focal elements 120, with the distance d being approximately 8.0 μm.

[0164] Laser processing of workpiece 104 with device 100 works as follows.

[0165] To perform laser processing, the focal element 120 is applied to the material 102 of the workpiece 104 and the focal element 120 is moved through the material 102 in a feed direction 126 relative to the workpiece 104 .

[0166] In this case, material 102 is a material that is transparent to the wavelength of the laser light at which each of the focusing elements 120 is formed, for example a glass material. In the embodiment shown, the focusing elements are formed by beam shaping of an input laser beam 108.

[0167] Applying focal element 120 to material 102 creates a material modification 138 in material 102 that is located in a cross section oriented perpendicular to feed direction 126 along process line 136 (FIG. 8a). In the example shown in FIG. 8a, material modification 138 is created continuously throughout the thickness D of material 102.

[0168] A processing surface 144 corresponding to processing line 136 is formed by relative movement of focal element 120 with respect to material 102 along path 142, and material modification 138 is disposed thereon. This results in the planar formation and / or placement of material modification 146 along processing surface 144.

[0169] The path 142 can in principle have straight and curved sections. In the case of curved sections, the processing line 136 is specifically redirected during laser processing so 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 splitting element 106 or by a relative rotation of the entire device 100 with respect to the workpiece 104.

[0170] 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.

[0171] The material modification 146 created along the processing line 136 specifically results in a reduction in the strength of the material 102. This allows the material 102 to be cut into two distinct workpiece segments 146a, 146b after the material modification 146 has been created on the processing surface 144, for example by applying a mechanical force (FIG. 8b).

[0172] Workpiece segment 146a in the illustrated embodiment is a yield segment having a cutting surface 148 with a shape corresponding to the shape of process line 136. In this case, workpiece segment 154a is a remainder workpiece segment and / or a scrap segment.

[0173] For example, the material 102 of the workpiece 104 is fused silica. To produce the material modification 138, e.g., as a Type I modification and / or a Type II modification, the laser beam formed by the focusing element 120 has a wavelength of 1030 nm and a pulse duration of 1 ps. Furthermore, the numerical aperture associated with the focusing optical unit 118 is 0.4, and the pulse energy associated with a single focusing element 120 is 50-200 nJ.

[0174] To produce the material modification 138 as a Type III modification, the pulse energy associated with a single focal element 120 is 500-2000 nJ, with otherwise identical parameters. [Explanation of symbols]

[0175] α angle of attack d distance d0 distance d eff Effective distance d x,eff Effective distance component d z,eff Effective distance component D Thickness I strength Position in x0x direction Position in the y0y direction Position in z0z direction 100 devices 102 Material 104 workpieces 106 Beam Splitting Elements 108 input laser beam 110 Laser beam source 112 Beam cross section 114 Wavefront 116 Sub Beam 116a Sub Beam 116b Sub-Beam 118 Focusing Optical Unit 120 focal elements 120a, 120b focal element 121 Focal distribution 122 Beam former 124 Beam Propagation Direction 126 Feeding direction 127 Feeding device 130 first outer side 132 Second outer side 134 Thickness direction 136 Processing line 137 Crack 138 Material Modification 139 Projection plane 140 parts 140a First Part 140b Second part 140c Third Part 141 plane 141a First Plane 141b Second Plane 142 routes 143 Gap 144 Processed surface 146a Workpiece segment 146b Workpiece segment 148 Cutting surface

Claims

1. 1. A method for laser processing a workpiece (104) having a transparent material (102), comprising: splitting an input laser beam (108) into multiple sub-beams (116) by a beam splitting element (106); focusing the combined output sub-beams (116) from the beam splitting element (106); forming multiple focusing elements (120) by focusing the sub-beams (116); applying the focusing elements (120) to the material (102) of the workpiece (104) for laser processing; and a feed direction (126) relative to the material (102), the method being characterized in that a portion of the formed focusing elements (120a) is arranged in a first plane (141a) and a portion of the formed focusing elements (120b) is arranged in at least one other plane (141b), the first plane (141a) and the at least one other plane (141b) are spaced apart parallel to the feed direction (126), and the first plane (141a) and the at least one other plane (141b) are oriented perpendicular to the feed direction (126).

2. The formed focal elements (120) are arranged such that when the focal elements (120) are viewed in a projection plane (139) oriented perpendicular to the feed direction (126), at least one fraction of the focal elements (120) associated with the first plane (141 a) and the focal elements (120) associated with the at least one other plane (141 b) are positioned at different spatial positions (x) in the projection plane (139). ０ , y ０ , z ０ 2. The method of claim 1, wherein the sensor is positioned so as to be disposed on a surface of the sensor.

3. 3. The method of claim 1, wherein the formed focal elements are positioned such that, when the focal elements are viewed in a projection plane oriented perpendicular to the feed direction, at least a partial amount of the focal elements associated with the first plane and the focal elements associated with the at least one other plane are positioned in the projection plane along a processing line, and a relative movement of the focal elements with respect to the material in the feed direction produces a material modification in the material that is arranged along the processing line.

4. 4. The method of claim 3, wherein the relative movement of the focal element within the material produces a material modification along a processing surface corresponding to the processing line, the material modification being located in a cross section oriented perpendicular to the feed direction and passing through the processing surface along the processing line.

5. Adjacent focal 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 5. The method according to claim 3 or 4, characterized in that it comprises

6. The effective distance (d ｅｆｆ 6. The method according to claim 3, wherein the intensity (I) of the focusing element (120) and / or the force (I) of the focusing element (120) are selected such that application of the focusing element (120) to the material (102) and relative movement of the focusing element (120) with respect to the material (102) in the feed direction (126) results in the formation of a material modification (138) in the material (102) that enables cutting of the material (102).

7. At least a portion of adjacent focal elements (120) arranged along said processing line (136) are at the same effective distance (d ｅｆｆ 7. The method according to claim 3, wherein the projection plane (139) is at least approximately spaced apart with a distance (139) between the projection plane (139) and the projection plane (139).

8. At least a portion of the mutually adjacent focal elements (120) arranged along the processing line (136) have an effective distance (d ｅｆｆ ) and the effective distance (d ｅｆｆ ) has a non-zero effective distance component (d ｚ，ｅｆｆ ) and / or an additional effective distance component (d) different from zero oriented perpendicular to the thickness direction (134) of the workpiece (104). ｘ，ｅｆｆ 8. The method according to claim 3, wherein the hydroxyl group is hydroxypropyl methylcellulose.

9. 9. The method according to claim 3, wherein the angle of attack (α) between the processing line (136) and the outer side (130) of the workpiece (104), through which the focusing element (120) for laser processing is coupled into the material (102) of the workpiece (104), is at least in some parts at least 1° and / or at most 90°, in particular at most 89°.

10. 10. The method according to claim 9, wherein the formed focal elements (120) are positioned such that, when the focal elements (120) are viewed in a projection plane (139) oriented perpendicular to the feed direction (126), a gap (143) is formed between adjacent focal elements (120a) associated with the first plane (141a), and there is a focal element (120b) associated with the at least one other plane (141b) arranged within the gap (143).

11. 10. The method according to claim 1, wherein the distance (d) between adjacent focal elements (120a) associated with the first plane (141a) is at least 3 μm and / or at most 70 μm, in particular at least 5 μm and / or at most 10 μm, and / or the distance (d) between adjacent focal elements (120b) associated with the at least one other plane (141b) is at least 3 μm and / or at most 70 μm, in particular at least 5 μm and / or at most 10 μm.

12. 10. The method of claim 9, wherein the splitting of the input laser beam (108) by the beam splitting element (106) is performed by or includes phase imprinting of the input laser beam (108) into a beam cross section (112) of the input laser beam (108).

13. 10. The method of claim 1, wherein a material modification (138) is produced in the material (102) of the workpiece (104) by applying the focal element (120) to the material (102), the material modification (138) involving crack formation in the material (102), and / or the material modification (120) is a type III material modification.

14. 10. The method of claim 1, wherein a material modification (138) is created in the material (102) of the workpiece (104) by applying the focusing element (120) to the material (102), the material modification (138) involving a change in the refractive index of the material (102) and / or the material modification (138) being a type I material modification and / or a type II material modification.

15. A device 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); a focusing optical unit (118) for focusing the sub-beams (116) combined out of the beam splitting element (106), wherein a plurality of focusing elements (120) for laser processing the workpiece (104) are formed by focusing the sub-beams (116); and a focusing optical unit (118) for moving the focusing elements (120) relative to the material (102) of the workpiece (104) in a feed direction (126). and a feeding device (127) for applying a beam splitting element (106) to the beam splitting element (106), wherein the beam splitting element (106) and the focusing optical unit (118) are configured to position the focusing elements (120) such that a partial amount of the formed focusing elements (120a) is arranged in a first plane (141a) and a partial amount of the formed focusing elements (120b) is arranged in at least one other plane (141b), wherein the first plane (141a) and the at least one other plane (141b) are spaced apart parallel to the feeding direction (126), and the first plane (141a) and the at least one other plane (141b) are oriented perpendicular to the feeding direction (126).

Images