Apparatus and method for laser processing a workpiece

Abstract

The invention relates to an apparatus for laser processing a workpiece (70), comprising a beam shaping device (16, 16') for forming a focal region (18) from an input laser beam (14) incident on the beam shaping device (16, 16'), and a telescope device (34, 34') for imaging the focal region (18) into a material (72) of the workpiece (70), wherein the beam shaping device (16, 16') is configured to phase-impose on a beam cross section of the input laser beam (14) such that the focal region (18) extends along a longitudinally central axis (40) which is at least section-wise curved, and the focal region (18) has an asymmetric cross section in a plane which is oriented perpendicularly with respect to the longitudinally central axis (40).

Description

TECHNICAL FIELD

[0001] The invention relates to an apparatus for laser machining a workpiece.

[0002] The invention also relates to a method for laser machining a workpiece. BACKGROUND

[0003] EP 2 859 984 B1 discloses a method for laser machining a transparent material, during the course of which a laser beam comprising a burst of laser pulses is provided and the pulses of the laser beam are focused, wherein the focusing is performed by means of one or more aberrated optical elements in order to form a beam waist at a location outside the transparent material in order to produce a dispersed focus inside the transparent material along a longitudinal axis of the laser beam, and wherein the focused laser beam has a sufficient energy density inside the transparent material to form and maintain a continuous laser filament in the transparent material, wherein the laser energy deposited along the continuous laser filament leads to an internal modification of the material, wherein the internal modification has a shape defined by the continuous filament.

[0004] US 10,173,916 B2 discloses a method for chamfering and / or beveling an edge of a glass substrate using a laser.

[0005] US 2020 / 0147729 A1 discloses a cutting method for forming beveled corners by means of different light patterns based on a Gaussian beam. SUMMARY

[0006] The task on which the invention is based is to provide the apparatus mentioned at the outset by means of which a workpiece can be laser machined along a curved machining line in a technically simple manner.

[0007] This task is achieved according to the invention in the apparatus mentioned at the outset by the beam shaping device for forming a focal region from an input laser beam incident on the beam shaping device and by the telescope device for imaging the focal region into the material of the workpiece, wherein the phase of the beam cross section of the input laser beam is imposed by means of the beam shaping device such that the focal region extends along a longitudinally centrally curved longitudinal center axis and the focal region has an asymmetric cross section in a plane oriented perpendicularly with respect to the longitudinal center axis.

[0008] By means of the beam shaping device it is made possible to achieve the mentioned focal region by correspondingly imposing the phase on the beam cross section of the input laser beam in a technically simple manner and with a small number of components.

[0009] In particular, the focal zone forms an interaction region, wherein the loading of this interaction region with material of the workpiece makes it possible to form a localized material modification, which in particular enables material separation.

[0010] Since the focal zone extends along the at least sectionally curved longitudinal center axis, it is possible, for example, to process the at least sectionally curved region on the workpiece in a single pass and / or without the use of optical units. This makes it possible, for example, to modify and / or separate the rounded region on the workpiece. For example, it is thereby possible to round the edge region of the workpiece.

[0011] By means of the asymmetric cross section of the focal zone, it is possible to control and / or optimize the formation of cracks between the modified regions adjacent to one another in the feed direction. In particular, it is thereby possible to orient the cracks at least approximately parallel to the shortest connecting line between the adjoining modified regions. It is thereby possible to achieve an optimized separation of the workpiece.

[0012] In particular, it can be provided that the phase distribution of the coupled-out sub-beams on the beam exit side of the beam shaping device is non-continuous and / or has jump sites. It is thereby possible to produce the focal zone having an asymmetric cross section by means of interference and in particular incomplete structure interference of the coupled-out sub-beams.

[0013] The asymmetric cross section is in particular to be understood as meaning that the diameter of the beam and / or of the focal zone has different diameters in the x direction and the y direction, wherein the x direction and the y direction are in particular oriented perpendicular to one another and / or lie in a plane oriented perpendicular to the beam propagation direction.

[0014] In order to determine the spatial dimensions of the focal zone, for example the length and / or the diameter of the focal zone, the focal zone is observed in a modified intensity distribution, which only has intensity values above a determined intensity threshold, wherein the intensity threshold is in particular 50% of the global intensity maximum of the actual intensity distribution. The length of the focal zone or the diameter of the focal zone is to be understood as meaning the maximum extension length and / or the maximum extension dimension of the focal zone obtained on the basis of the modified intensity distribution along the longitudinal center axis of the focal zone or in a plane oriented perpendicular to the longitudinal center axis.

[0015] In particular, the longitudinal center axis of the focal zone is curved and / or continuously curved and / or curved over the entire length of the focal zone.

[0016] The task mentioned at the outset is also achieved according to the application in the device mentioned at the outset, which comprises a beam-shaping device for forming a focal region from an input laser beam incident on the beam-shaping device; and a telescope device for imaging the focal region into the material of the workpiece, wherein the phase application onto the beam cross section of the input laser beam is achieved by means of the beam-shaping device in such a way that the focal region extends along an at least section-wise curved longitudinal center axis, wherein the telescope device is assigned a beam-splitting device for splitting the sub-beams coupled out of the beam-shaping device into a plurality of polarized sub-beams, which each have one of at least two different polarization states, wherein the telescope device with the beam-splitting device is configured for focusing the polarized sub-beams into a first sub-focal region formed by the first sub-beams having a first polarization state and a second sub-focal region formed by the second sub-beams having a second polarization state, so that the focal region is formed at least section-wise from the spatial overlap of the first sub-focal region and the second sub-focal region and has an asymmetric cross section in a plane oriented perpendicularly with respect to the longitudinal center axis.

[0017] In this variant of the application, the asymmetric cross section of the focal region is achieved by splitting the beam using the beam-splitting device. Thereby, the focal region is formed, inter alia, from the incoherent overlap and / or superposition of the first sub-beams having the first polarization state and the second sub-beams having the second polarization state.

[0018] In principle, it is also possible to form sub-beams having more than two different polarization states by means of the beam-splitting device and / or the focal region to be formed from more than two different sub-focal regions.

[0019] Overlap is to be understood, inter alia, as at least partial spatial overlap, wherein this is used, inter alia, to increase the intensity of the first sub-focal region and the intensity of the second sub-focal region.

[0020] Sub-beams having different polarization states are to be understood, inter alia, as linearly polarized sub-beams, wherein, inter alia, the polarization direction of the first sub-beams having the first polarization state and the polarization direction of the second sub-beams having the second polarization state are oriented at an angle of 90° with respect to one another.

[0021] It can be provided, inter alia, that the focal region is formed at least section-wise from the overlap of the spatial intensity distribution of the first sub-focal region and the spatial intensity distribution of the second sub-focal region. This makes it possible to form the focal region having an asymmetric cross section in a technically simple manner.

[0022] In principle, the focal region can also be formed completely from the spatial overlap of the first sub-focal region and the second sub-focal region.

[0023] It can be advantageous if the first sub-focal zone extends along a first longitudinal central axis and the second sub-focal zone extends along a second longitudinal central axis, wherein the first longitudinal central axis and the second longitudinal central axis each at least section-wise have a curved shape. Thereby, it is possible to form a focal zone having a curved shape and an asymmetric cross section.

[0024] For the same reason, it can be advantageous if the first longitudinal central axis and the second longitudinal central axis have a positional offset in a direction oriented perpendicularly with respect to the first longitudinal central axis and / or the second longitudinal central axis.

[0025] For the same reason, it can be advantageous if the first longitudinal central axis and the second longitudinal central axis at least approximately continue parallel to one another.

[0026] It can be provided, in particular, that the first sub-beam and the second sub-beam are incoherent with one another and / or that the first sub-beam and the second sub-beam do not have a fixed phase relationship with one another. Thereby, the focal zone is formed, in particular, by incoherent superimposition and / or superposition of the first sub-beam and the second sub-beam.

[0027] It can be provided, in particular, that the beam splitting device is arranged in a far field region of the telescope device and / or that the beam splitting device is at least approximately arranged in a focal plane of the telescope device. Thereby, the beam splitting device can be integrated in the telescope device in a technically simple manner.

[0028] The far field region is to be understood, in particular, as a region within the beam path of the telescope device in which there is an annular intensity distribution about the optical axis of the telescope device.

[0029] It can be provided, in particular, that the telescope device has a first lens element and a second lens element spaced apart from the first lens element in the beam propagation direction, wherein the beam splitting device is arranged between the first lens element and the second lens element and / or wherein the beam splitting device is at least approximately arranged in a focal plane of the first lens element and / or a focal plane of the second lens element.

[0030] It can be provided, in particular, that the beam splitting device is or comprises a beam splitting optical, in particular a polarization beam splitting optical. The beam splitting optical is made of or comprises, for example, a quartz crystal.

[0031] The beam splitting device has, for example, at least one birefringent element, in particular at least one birefringent wedge element.

[0032] It can be advantageous if the beam splitting device has a birefringent polarizer element by means of which a positional offset and an angular offset are produced between the first sub-beam and the second sub-beam coupled out of the beam splitting device.

[0033] In particular, the beam splitting device comprises a further optical element, for example an isotropic element or a further birefringent polarizer element, arranged downstream of the birefringent polarizer element in the longitudinal direction.

[0034] In particular, the further optical element is configured for modifying a positional offset and / or an angular offset between the first sub-beam and the second sub-beam coupled out of the beam splitting device.

[0035] Preferably, the further optical element is provided for orienting the first sub-beam parallel to the optical axis of the telescope device.

[0036] It can be advantageous if the beam splitting device is used for splitting the incident beam into sub-beams different from one another with different polarization states, respectively, wherein the sub-beams coupled out of the beam splitting device and having different polarization states have an angular offset. After the sub-beams have been imaged by means of the telescope device, the angular offset leads to a positional offset of the sub-beams having different polarization states.

[0037] In particular, it can be provided that the first sub-beam coupled out of the beam splitting device and having a first polarization state is oriented parallel to the optical axis of the telescope device. This leads to a reduced adjustment complexity.

[0038] The two above-mentioned variants of the device according to the application each have one or more of the features and / or advantages described below, in particular.

[0039] In particular, it can be provided that the focal region and / or the intermediate image assigned to the focal region is formed by interference, in particular constructively by interference, of the sub-beams coupled out of the beam shaping device.

[0040] In particular, it can be provided that the telescope device has a first lens element and a second lens element spaced apart from the first lens element in the beam propagation direction, wherein the first lens element is used for coupling the beam into the telescope device and / or the second lens element is used for coupling the beam out of the telescope device.

[0041] In particular, it can be provided that the telescope device has a first lens element and a second lens element spaced apart from the first lens element in the beam propagation direction, wherein the first lens element has a greater focal width than the second lens element.

[0042] In one embodiment, the first lens element of the telescope device is integrated in or provided on the beam shaping device. In particular, the function of the first lens element is integrated in the beam shaping device.

[0043] In particular, it can be provided that the longitudinal center axis of the focus region has at least section- wise a radius of curvature of at least 50 pm and / or at most 100 mm, and / or that the longitudinal center axis of the focus region has an average radius of curvature of at least 200 pm and / or at most 2 mm.

[0044] For example, the focus region and / or the longitudinal center axis of the focus region has a U-shaped shape and / or a C-shaped shape and / or a hyperbolic shape.

[0045] In particular, it can be provided that the focus region and / or the longitudinal center axis of the focus region extends at least approximately along an arcuate portion.

[0046] For example, the center point angle of the arcuate portion is at least 1° and / or at most 90°.

[0047] For example, the focus region and / or the longitudinal center axis of the focus region extends at least section- wise along a quarter circle.

[0048] In particular, it can be provided that the focus region has a spatially continuous design. In particular, the first sub-focus region and / or the second sub-focus region has a spatially continuous design.

[0049] In particular, the focus region and / or the longitudinal center axis of the focus region has a continuous and / or distinguishable shape. In particular, the focus region and / or the longitudinal center axis does not have any discontinuity and / or jump.

[0050] In particular, the focus region has a linear form and / or an elongated form and / or a long form.

[0051] For example, the length of the focus region is more than 10 times, in particular more than 50 times, the maximum diameter of the focus region.

[0052] In particular, it can be provided that the focus region has a length of at least 50 pm and / or at most 20 mm, in particular a length of at least 500 pm and / or at most 2 mm.

[0053] In particular, it can be provided that the maximum diameter of the focus region is at least 500 nm and / or at most 5 pm.

[0054] It can be advantageous if the maximum diameter of the focus region in a plane oriented perpendicularly with respect to the longitudinal center axis of the focus region is at least approximately constant along the longitudinal center axis. This makes it possible to achieve an approximately uniform machining of the material over the entire length of the focus region.

[0055] It can be advantageous that the quasi-non-diffracting beam and / or the Bessel-like beam can be generated by means of a beam shaping device or are generated by means of a beam shaping device. Thereby, inter alia, a focal region is provided which has a transversal intensity distribution which is at least approximately constant in the longitudinal direction, wherein the transversal intensity distribution is to be understood as the intensity distribution in a plane which is oriented perpendicularly with respect to a longitudinal center axis of the focal region.

[0056] In particular, the focal region has a quasi-non-diffracting beam profile and / or a Bessel-like beam profile.

[0057] The quasi-non-diffracting beam and / or the Bessel-like beam is to be understood in particular as meaning an average beam whose transversal intensity distribution is propagation-invariant. In particular, in the case of a quasi-non-diffracting beam and / or a Bessel-like beam, the transversal intensity distribution of the beam is essentially constant in the longitudinal direction and / or the beam propagation direction.

[0058] The transversal intensity distribution is to be understood as the intensity distribution in a plane which is oriented perpendicularly with respect to the longitudinal direction and / or the beam propagation direction of the beam.

[0059] With regard to the definition and properties of quasi-non-diffracting beams, reference is made to the following book: “Structured Light Fields: Applications in Optical Trapping, Manipulation and Organisation”, M. Wördemann, Springer Science & Business Media (2012), ISBN 978-3-642-29322-1.

[0060] With regard to the formation and properties of quasi-non-diffracting beams and / or Bessel-like beams having a curved shape, reference is made to the scientific publication “Bessel-like optical beams with arbitrary trajectories”, I. Chremmos et al., Optics Express, Vol. 37, No. 23, 1 December 2012.

[0061] With regard to the formation and properties of quasi-non-diffracting beams and / or Bessel-like beams having an asymmetric cross section, reference is made to the scientific publication “Generalized axicon-based generation of nondiffracting beams”, K. Chen et al., arXiv:1911.03103v1 [physics.optics], 8 November 2019.

[0062] In particular, it can be provided that the focal region has an elliptical cross section in a plane which is oriented perpendicularly with respect to a longitudinal center axis of the focal region. This makes it possible, in particular, to control the formation of cracks and / or the orientation of cracks formed during laser machining of the workpiece.

[0063] For the same reason, it can be advantageous for the largest diameter of the cross-sectional ellipse of the focal region to be oriented at least approximately parallel to the feed direction in which the workpiece is moved relative to the focal region in order to form the machining line and / or the machining surface. Thereby, in particular, cracks formed during laser machining are oriented at least approximately parallel to the feed direction.

[0064] In particular, it can be advantageous for an intermediate image of the focal region to be formed by means of a beam shaping device, wherein the focal region is formed by imaging the intermediate image by means of a telescope device. The telescope device can be used to adjust the length of the focal region, in particular, depending on the application.

[0065] In particular, it can be provided that the intermediate image is arranged, in the beam propagation direction, between the beam shaping device and a second lens element for coupling out the beam from the telescope device and / or between the beam shaping device and a beam splitting device for splitting the sub-beam coupled out of the beam shaping device into a plurality of polarized sub-beams.

[0066] It can be advantageous for the beam shaping device and / or the beam splitting device to be rotatable relative to the optical axis of the telescope device, in particular, about the optical axis of the telescope device. This makes it possible to adjust the orientation of the focal region relative to the workpiece.

[0067] In particular, it can be provided that the device comprises a laser source for providing the input laser beam, wherein, in particular, a pulsed laser beam or an ultrashort pulsed laser beam is provided by means of the laser source.

[0068] For example, the wavelength of the input laser beam is at least 300 nm and / or at most 1500 nm. For example, the wavelength is 515 nm or 1030 nm.

[0069] In particular, the machining beam has an average power of at least 1 W to 1 kW. For example, the machining beam comprises pulses having a pulse energy of at least 10 µJ and / or at most 50 mJ. It can be provided that the machining beam comprises individual pulses or burst pulses, wherein the burst pulses have 2 to 20 sub-pulses and, in particular, a time interval of approximately 20 ns.

[0070] It can be advantageous for the beam shaping device to have at least one diffractive optical element or to be in the form of a diffractive optical element.

[0071] In principle, the beam shaping device can also be in the form of a refractive and / or reflective optical element.

[0072] For example, the beam shaping device is or comprises an axicon element.

[0073] It can be advantageous if the phase distribution of the sub-beams coupled out on the beam exit side of the beam shaping device is non-symmetrical and / or non-rotationally symmetrical. In particular, the phase distribution is non-symmetrical and / or non-rotationally symmetrical with respect to the beam axis of the input laser beam and / or with respect to the optical axis of the beam shaping device. This makes it possible to produce a focus region in the form of, for example, a curved Bessel-like beam and / or an accelerated Bessel-like beam.

[0074] It can be advantageous if the device comprises a further telescope device for controlling the diameter of the input laser beam incident on the beam shaping device. This makes it possible to control and / or adjust the length of the focus region.

[0075] For example, the further telescope device is arranged upstream of the beam shaping device in the beam propagation direction.

[0076] According to the application, a method for laser machining a workpiece is provided, in the course of which a focus region is formed from an input laser beam incident on a beam shaping device using the beam shaping device, wherein the focus region is imaged or can be imaged into the material of the workpiece by means of a telescope device, and wherein the beam shaping device is used for phase imposition on a beam cross section of the input laser beam such that the focus region extends along an at least section-wise curved longitudinal central axis and the focus region has a non-symmetrical cross section in a plane oriented perpendicularly with respect to the longitudinal central axis.

[0077] According to the application, a further method for laser machining a workpiece is provided, in the course of which a beam shaping device is used to form a focus region from an input laser beam incident on the beam shaping device, wherein the focus region is imaged or can be imaged into the material of the workpiece by means of a telescope device, the beam shaping device is used for phase imposition on a beam cross section of the input laser beam such that the focus region extends along an at least section-wise curved longitudinal central axis, a beam splitting device assigned to the telescope device is used to split sub-beams coupled out from the beam shaping device into a plurality of polarized sub-beams, each of the plurality of polarized sub-beams having one of at least two different polarization states, the polarized sub-beams are focused into a first sub-focus region formed by first sub-beams having a first polarization state and a second sub-focus region formed by second sub-beams having a second polarization state, whereby the focus region is formed at least section-wise from a spatial overlap of the first sub-focus region and the second sub-focus region, and the focus region has a non-symmetrical cross section in a plane oriented perpendicularly with respect to the longitudinal central axis.

[0078] The method according to the application has in particular one or more features and / or advantages of the device according to the application described above. Advantageous configurations of the method according to the application have been explained in connection with the device according to the application.

[0079] In particular, it can be provided that the workpiece is made of and / or consists of a material which is transparent to the wavelength of the input laser beam and / or to the wavelength of the focus zone formed by the input laser beam. For example, the material of the workpiece is glass or comprises glass.

[0080] Transparent material is to be understood as meaning in particular a material which is transmissive to at least 70%, in particular at least 80%, in particular at least 90% of the laser energy of the machining beam.

[0081] In particular, it can be provided that the focus zone is applied to the workpiece to perform laser machining, and in particular the workpiece is moved along a machining line or machining surface relative to the focus zone. This makes it possible to form material modifications arranged along the machining line or machining surface in the workpiece.

[0082] In particular, it can be provided that, after the laser machining has been performed, the workpiece can be separated along the machining line and / or machining surface, or the workpiece is separated along the machining line and / or machining surface.

[0083] It can be advantageous that the material of the workpiece can be separated along the machining line and / or machining surface by applying a thermal load and / or mechanical stress and / or by etching by means of at least one wet-chemical solution, or that the material of the workpiece is separated along the machining line and / or machining surface by applying a thermal load and / or mechanical stress and / or by etching by means of at least one wet-chemical solution.

[0084] In particular, it can be provided that the input laser beam is a pulsed laser beam or an ultrashort pulsed laser beam, and / or the focus zone is formed by means of a pulsed laser beam or an ultrashort pulsed laser beam.

[0085] In particular, an axis system for moving and / or tilting the workpiece relative to the focus zone is provided.

[0086] Adjustment electronics for a spatially resolved pulse control, in particular containing on-demand pulses, can be provided to control the laser source for providing the input laser beam.

[0087] In particular, a workpiece mount for the workpiece is provided, which has in particular a non-reflective and / or strongly scattering surface.

[0088] The aforementioned properties of the focus zone essentially relate to the properties of the focus zone in air and / or the properties of the focus zone outside the workpiece, unless stated otherwise.

[0089] In particular, the indications "approximately" and "at least approximately" are generally to be understood as a deviation of not more than 10%. Unless stated otherwise, the indication "approximately" or "at least approximately" is to be understood as meaning, in particular, that the actual value and / or distance and / or angle deviates from the ideal value and / or distance and / or angle by not more than 10%. BRIEF DESCRIPTION OF DRAWINGS

[0090] The following description of preferred embodiments serves to explain the present application in greater detail,

[0091] In the drawings:

[0092] Figure 1 A schematic cross-sectional view of one embodiment of an apparatus for laser processing a workpiece is shown, in which two different variants are indicated;

[0093] Figure 2 A schematic cross-sectional view of a partial region of a further embodiment of an apparatus for laser processing a workpiece is shown, in which two different variants are indicated;

[0094] Figure 3 A schematic view of the phase distribution of the sub-beams on the beam exit side of a first embodiment of a beam shaping device of the apparatus is shown;

[0095] Figure 4 A simulated intensity distribution of a focal region having a curved profile in a z-x plane oriented parallel to the longitudinal central axis of the focal region is shown;

[0096] Figure 5 A simulated cross-sectional view of the intensity distribution of a focal region in an x-y plane oriented perpendicular with respect to the longitudinal central axis of the focal region is shown;

[0097] Figure 6 A schematic view of the phase distribution of the sub-beams on the beam exit side of a further embodiment of a beam shaping device of the apparatus is shown;

[0098] Figure 7 A schematic cross-sectional view of a first embodiment of a beam splitting device is shown;

[0099] Figure 8 A schematic cross-sectional view of a further embodiment of a beam splitting device is shown;

[0100] Figure 9a A schematic view of a focal region in a cross-section parallel to the longitudinal central axis of the focal region is shown, in which the focal region is formed by a spatial overlap of a first sub-focal region and a second sub-focal region;

[0101] Figure 9b A schematic view of a focal region in a cross-section parallel to the longitudinal central axis of the focal region is shown, in which the focal region is formed by a spatial overlap of a first sub-focal region and a second sub-focal region; Figure 9aa schematic cross-sectional view showing the intensity distribution of the focal region in an x-y plane oriented perpendicular to the longitudinal center axis of the focal region;

[0102] Figure 10 a schematic cross-sectional view showing the intensity distribution of the focal region in an x-y plane oriented perpendicular to the longitudinal center axis of the focal region;

[0103] Figure 10 b shows the intensity distribution of the focal region according to Figure 10 a in the x-direction at y = 0;

[0104] Figure 10 c shows the intensity distribution of the focal region according to Figure 10 a in the y-direction at x = 0;

[0105] Figure 11 a schematic cross-sectional view showing a workpiece being processed by means of a focal region along a processing line and / or a processing surface;

[0106] Figure 12a a perspective view showing an example of a workpiece being divided into two different sections along a processing line and / or a processing surface;

[0107] Figure 12b a perspective view showing a further example of a workpiece being divided into two different sections along a processing line and / or a processing surface;

[0108] Figure 13 a schematic cross-sectional view showing a partial area of a workpiece on a processing line and / or a processing surface, wherein cracks are formed between mutually spaced apart modified regions. DETAILED DESCRIPTION

[0109] In all embodiments, identical or functionally identical elements are denoted by identical reference signs.

[0110] A first embodiment of an apparatus for laser processing a workpiece is shown in Figure 1 and is denoted there with 10. By means of the apparatus 10 material modifications, for example sub-micron or atomic scale defects weakening the material, can be generated on a workpiece. Thereby it is made possible to separate the workpiece into two different sections from each other, for example in a subsequent step.

[0111] In particular, the apparatus 10 comprises a laser source 12 for providing an input laser beam 14. The input laser beam 14 is in particular a pulsed laser beam and / or an ultrashort pulsed laser beam. For example, the input laser beam 14 is a Gaussian beam and / or has a diffraction-limited beam profile.

[0112] The device 10 comprises a beam shaping apparatus 16 into which the input laser beam 14 can be coupled in. In particular, in the operating state of the device 10, the input laser beam 14 is coupled into the beam shaping apparatus 16.

[0113] The input laser beam 14 propagates along a longitudinal direction z. In particular, the longitudinal direction z is to be understood as the main beam propagation direction of the input laser beam 14 and / or of a beam formed by the input laser beam 14 through the device 10.

[0114] The wavelength of the input laser beam 14 is, for example, 515 nm or 1030 nm.

[0115] The beam shaping apparatus 16 applies a phase to a beam cross section of the input laser beam 14 to generate an elongated focal region 18. The cross section of the beam cross section is oriented perpendicular with respect to the longitudinal direction z and / or with respect to the beam propagation direction.

[0116] The input laser beam 14 impinges on the beam shaping apparatus 16 on a beam entry side 20 and is coupled into the beam shaping apparatus. On a beam exit side 22, which is positioned opposite the beam entry side 20, phase-modulated sub-beams 24 are coupled out of the beam shaping apparatus 16.

[0117] The sub-beams 24 coupled out of the beam shaping apparatus 16 are mutually coherent sub-beams, that is to say, the sub-beams 24, which differ from one another, have a fixed phase relationship with respect to one another.

[0118] The sub-beams 24 exiting from the beam shaping apparatus 16 are also inclined with a cone angle β1 with respect to the input laser beam 14 impinging on the beam shaping apparatus 16 and / or with respect to an optical axis 25 of the beam shaping apparatus 16. In particular, the sub-beams 24 have a conical profile and / or a conical envelope.

[0119] The interference of the sub-beams 24 leads to the formation of an intermediate image 26, which is attributed to the focal region 18 and is arranged downstream of the beam shaping apparatus 16 in the longitudinal direction z. The intermediate image 26 of the focal region 18 and / or the focal region 18 has an elongated and / or long shape.

[0120] In particular, the intermediate image 26 and / or the focal region 18 is oriented in the longitudinal direction z. For example, a main extension direction of the intermediate image 26 and / or a main extension direction of the focal region 18 is oriented along the longitudinal direction z and / or is oriented parallel to the optical axis 25.

[0121] The intermediate image 26 extends along a longitudinal center axis 27 (indicated by the dashed line in Figure 1 ). In this regard, the longitudinal center axis 27 is in particular an axis of symmetry of the intermediate image 26 in the longitudinal direction.

[0122] The first beamforming device 16 is in particular in the form of a diffractive optical element. For example, the first beamforming device is in the form of an axial tapered element.

[0123] The phase profile applied to the sub-beam 24 by means of the beamforming device 16 makes the intermediate image 26 and / or the focal region 18 have a quasi-non-diffractive beam profile and / or a Bessel-like beam profile.

[0124] Furthermore, the phase profile applied to the sub-beam 24 causes the intermediate image 26 and / or the focus region 18 to have a curved shape. Accordingly, the longitudinal central axis 27 has a curved shape, along which the intermediate image 26 extends.

[0125] Figure 3 An example of the phase distribution applied to the sub-beam 24 by means of the beamforming device 16 is shown. Figure 3 In the figure, the two-dimensional phase distribution of the sub-beam 24 emitted from the beamforming device 16 on the beam exit side 22 is depicted by means of grayscale profile, wherein the specified grayscale range is from white (phase + π) to black (phase - π).

[0126] The beam exit side 22 and / or phase distribution shown are located in a plane that is laterally oriented and, in particular, vertically oriented relative to the longitudinal direction z.

[0127] Each sub-beam 24 emitted from the beamforming device 16 at spatial positions X1 and Y1 on the beam exit side 22 is assigned a defined phase displacement value within the range of -π to +π, which is determined according to... Figure 3 The phase distribution shown here is visible in the example.

[0128] exist Figure 3 In the example shown, the phase distribution on the beam exit side 22 has an asymmetric profile, particularly a non-rotationally symmetric profile. This results in a phase profile being applied to the sub-beam 24, thereby creating a focused region with a curved profile through interference from the sub-beam 24. Consequently, the intermediate image 26 and / or the focused region 18 have curved profiles.

[0129] also, Figure 3 The phase distribution shown has one or more jump points 28, at which the phase profile between two adjacent partial regions 30a, 30b is discontinuous. For example, the phase shift and / or phase discontinuity between adjacent partial regions 30a, 30b has a value of π.

[0130] Jump point 28 should be understood as the dividing point and / or dividing line between the first part region 30a and the second part region 30b adjacent to the first part region 30a.

[0131] In particular, the phase difference between a first boundary point 32a, which is located on the jump site 28 in the first partial region 30a, and a second boundary point 32b, which is located on the jump site 28 in the second partial region 30b, is π.

[0132] In particular, the adjoining partial regions 30a, 30b are each a locally continuous partial region.

[0133] Due to the phase distribution being discontinuous and / or having a jump site, the phase profile imposed on the sub-beams 24 by means of the beam-shaping device 16 causes the intermediate image 26 and / or the focus region 18 to have an asymmetric beam cross-section. With regard to the intermediate image 26, the cross-sectional plane of the beam cross-section is oriented perpendicularly with respect to the longitudinal centre axis 27.

[0134] The apparatus 10 has a telescope device 34, which is arranged downstream of the intermediate image 26 in the beam propagation direction and / or in the longitudinal direction z. The focus region 18 is formed by the telescope device 34 imaging the intermediate image 26, wherein the telescope device 34 performs the imaging, in particular, with a reduced size.

[0135] The telescope device 34 has a first lens element 36 and a second lens element 38, which is spaced apart from the first lens element 36 in the longitudinal direction z.

[0136] The first lens element 36 is a telephoto lens element and / or an input lens element of the telescope device 34. The second lens element 38 is an output lens element and / or a short-focus lens element of the telescope device 34. The second lens element 38 is, in particular, in the form of and / or has the function of an objective.

[0137] The first lens element 36 and / or the second lens element 38 does not necessarily have to be formed in one piece. In particular, it can be provided that the first lens element 36 and / or the second lens element 38 is / are formed by and / or comprises a plurality of optical components in each case.

[0138] A first focal length f1 of the first lens element 36 is greater than a second focal length f2 of the second lens element 38. In particular, the ratio f1 / f2 is at least 5 and / or at most 50.

[0139] The telescope device 34 makes it possible to irradiate and / or image the focus region 18 into a workpiece to be machined. In particular, the telescope device 34 makes it possible to adjust the spatial dimensions of the focus region 18 to machine the workpiece.

[0140] In particular, the focus region 18 is to be understood as a focus region having at least approximately constant intensity and extending along a longitudinal centre axis 40 (indicated by the dashed line in Figure 1 In this regard, the longitudinal centre axis 40 is, in particular, an axis of symmetry of the focus region 18 in the longitudinal direction.

[0141] In particular, the focus region 18 has a focus area which extends along the longitudinal center axis 40 and which has an at least approximately constant intensity.

[0142] In particular, the focus region 18 has a spatially continuous design, that is to say, the focus intensity area of the focus region 18 has a spatially continuous design in each case.

[0143] However, it is also possible in principle for the intensity of the focus region 18 to vary along the longitudinal center axis and / or to be zero at isolated points.

[0144] In particular, the focus region 18 is to be understood as a focus area in which the intensity of the laser radiation is at least sufficiently large such that, when the focus region 18 is applied to the material of the workpiece, modified regions are produced within the material. In particular, the material can separate at these modified regions.

[0145] The longitudinal center axis 40 of the focus region 18 has an at least section-wise curved and / or continuously curved shape.

[0146] Figure 4 One embodiment of the focus region 18 is shown which exhibits an intensity distribution in the z-x plane which is oriented parallel to the longitudinal center axis 40. The lighter gray values represent greater intensities. In the embodiment according to Figure 4 The focus region 18 has an arcuate shape and / or a C-shaped shape in the embodiment according to

[0147] The focus region 18 is to be understood in particular as an overall maximum intensity distribution 42 which has a spatially continuous design in particular. In particular, only this overall maximum intensity distribution 42 is relevant for the interaction with the material to be machined for the purpose of forming a modification.

[0148] The maximum intensity distribution 42 is surrounded in particular by secondary intensity distributions 44. These secondary intensity distributions 44 are arranged in particular around and / or spaced apart from the maximum intensity distribution 42. The secondary intensity distributions 44 have in particular secondary maxima or comprise secondary maxima.

[0149] In particular, the secondary intensity distributions 44 are unimportant for the laser machining of the workpiece, since no and / or only negligible modifications are formed in the material of the workpiece due to the lower intensity.

[0150] The focus region 18 has an asymmetric beam cross section, wherein the cross section direction is oriented perpendicularly with respect to the longitudinal center axis 40. Figure 5 An example of the focus region 18 in the x-y plane which is oriented perpendicularly with respect to the longitudinal center axis 40 is shown.

[0151] In particular, the focal region 18 has a diameter dx along the x-direction and a diameter dy along a y-direction which is oriented perpendicular with respect to the x-direction, wherein the x-direction and the y-direction lie in a plane which is oriented perpendicular with respect to the longitudinal central axis 40.

[0152] In particular, it can be provided that the focal region 18 has an elliptical beam cross section. In this case, dx and dy are different. For example, dx is oriented parallel to a semi-major axis of the designated ellipse, while dy is oriented parallel to a semi-minor axis.

[0153] In a second variant of the apparatus 10, in comparison to the above-described first variant, the beam shaping device 16’ is configured to form an intermediate image 26’ which is attributed to the focal region 18 and which has an at least approximately symmetrical beam cross section.

[0154] The beam shaping device 16’ and the intermediate image 26’ have in particular one or more features and / or advantages of the above-described beam shaping device 16 and the above-described intermediate image 26, respectively.

[0155] The intermediate image 26’ extends along the longitudinal central axis 27 and has in particular a quasi-non-diffracting beam profile and / or a Bessel-like beam profile.

[0156] On the beam exit side 22, the sub-beams 24 which exit from the beam shaping device 16’ have a different phase distribution in comparison to the case of the above-described beam shaping device 16.

[0157] Figure 6 One example of a phase distribution which is imposed on the sub-beams 24 by means of the beam shaping device 16’ is shown in the form of a gray-scale distribution (analogous to Figure 3 ). The phase distribution on the beam exit side 22 has an asymmetric, in particular non-rotationally symmetric profile. This results in a phase-imposed profile on the sub-beams 24 such that, by interference of the sub-beams 24, a focal region having a curved profile is formed. Thereby, the intermediate image 26’ and / or the focal region 18 have a curved profile.

[0158] In particular, Figure 6 The shown phase distribution is continuous, in particular overall continuous. In particular, Figure 6 The shown phase distribution has no discontinuities and / or jump locations. This results in a phase-imposed profile on the sub-beams 24 such that, by interference of the sub-beams 24, a focal region having a symmetrical beam cross section is formed. Thereby, the intermediate image 26’ has a symmetrical beam cross section, wherein the cross section direction is oriented perpendicular with respect to the longitudinal central axis 27.

[0159] In order to realize an asymmetric beam cross section of the focal region 18, the apparatus 10 in the second variant comprises a beam splitting device 46 which is attributed to the telescope device 34 (by Figure 1(Indicated by the dashed line in the diagram). For example, beam splitting device 46 is part of telescope assembly 34 and / or disposed in the beam path of telescope assembly 34. For example, beam splitting device 46 is or includes a polarization beam splitting optical unit.

[0160] The beam splitting device 46 is particularly disposed in the far-field region 48 and / or in the focal plane 50 of the telescope assembly 34. For example, the focal plane 50 is the focal plane of the first lens element 36 and / or the focal plane of the second lens element 38.

[0161] Sub-beams 24 coupled from beamforming device 16' and / or beams originating from intermediate image 26' are incident beams 52 and irradiate beam splitting device 46. These incident beams 52 are each split into different sub-beams 54a, 54b with different polarization states by means of beam splitting device 46.

[0162] exist Figure 7 In the example of the beam splitting device 46 shown, the incident beam 52 is split into a first sub-beam 54a having a first polarization state and a second sub-beam 54b having a second polarization state by the beam splitting device 46.

[0163] The first polarization state and the second polarization state are particularly polarization states that are perpendicular to each other, and / or linear polarization states. In particular, the first sub-beam 54a and the second sub-beam 54b are polarized such that the electric field lies in a plane perpendicular to the longitudinal direction z and / or the beam propagation direction (lateral electric field).

[0164] The first sub-beam 54a has a positional offset Δx and an angular offset Δα relative to the second sub-beam 54b.

[0165] In particular, the first sub-beam 54a is oriented at least approximately parallel to the optical axis 56 of the telescope device 34, wherein the optical axis 56 is oriented, for example, parallel to or coincident with the optical axis 25 of the beamforming devices 16, 16'.

[0166] With the aid of telescope device 34 and / or with the aid of second lens element 38, the first sub-beam 54a coupled from beam splitting device 46 is imaged into first sub-focusing region 58a. Correspondingly, with the aid of telescope device 34 and / or with the aid of second lens element 38, the second sub-beam 54b coupled from beam splitting device 46 is imaged into second sub-focusing region 58b. Figure 9a and Figure 9b ).

[0167] Due to the angular offset between the first sub-beam 54a and the second sub-beam 54b, after focusing by means of the telescope device 34, the positions of the first sub-focusing region 58a and the second sub-focusing region 58b are offset by Δb in the direction perpendicular to the longitudinal central axis 40.

[0168] The first sub-focusing region 58a extends along the first longitudinal central axis 60a, while the second sub-focusing region 58b extends along the second longitudinal central axis 60b. The first longitudinal central axis 60a and the second longitudinal central axis 60b extend along the longitudinal direction z and / or the beam propagation direction.

[0169] In particular, the first sub-focusing region 58a and the second sub-focusing region 58b each have at least approximately symmetrical beam cross sections, wherein the cross section directions are respectively oriented perpendicular to the first longitudinal central axis 60a and the second longitudinal central axis 60b.

[0170] The focusing region 18 is formed by at least partial spatial overlap and / or superposition of the first sub-focusing region 58a and the second sub-focusing region 58b. The resulting focusing region 18 has an asymmetric, particularly elliptical, beam cross-section (see [reference]). Figure 9a and Figure 9b ).

[0171] The first sub-beam 54a and the second sub-beam 54b are mutually uncoordinated sub-beams and / or do not have a fixed phase relationship with each other, so in particular, the first sub-beam 54a and the second sub-beam 54b do not interfere with each other. Therefore, in the case of spatial overlap between the first sub-beam 54a and the second sub-beam 54b, it is thus the sum of the respective intensities of the first sub-beam 54a and the second sub-beam 54b.

[0172] exist Figure 9a and Figure 9b In the example shown, the first longitudinal central axis 60a is oriented at least approximately parallel to the second longitudinal central axis 60b. The longitudinal central axis 40 of the focal region 18 is symmetrical with respect to the first longitudinal central axis 60a and the second longitudinal central axis 60b and / or located at the center.

[0173] exist Figure 7 In the example shown, the beam splitting device 46 includes a birefringent polarizer element 62. The birefringent polarizer element 62 generates both a positional offset Δx and an angular offset Δα between the first sub-beam 54a and the second sub-beam 54b.

[0174] A beam incident side 64 and / or a beam incident surface of a beam splitting device 46 are formed on the birefringent polarizer element 62.

[0175] The optical axis 66 of the birefringent polarizer element 62 is oriented at an angle of, for example, 45° relative to the beam incident side 64 and / or relative to the optical axis 56 of the telescope assembly 34.

[0176] The beam splitting device 46 further comprises an isotropic element 68 which is arranged downstream of the birefringent polarizer element 62 along the longitudinal direction z. The first sub-beams 54a are oriented parallel to the optical axis 56 by means of the isotropic element 68.

[0177] The birefringent polarizer element 62 and / or the isotropic element 68 has, for example, a wedge design.

[0178] Figure 8 A further embodiment shown differs from the embodiment according to Figure 7 the main difference being that the first sub-beams 54a are oriented parallel to and lie in the optical axis 56 of the telescope device 34.

[0179] For the parallel orientation of the first sub-beams 54a relative to the optical axis 56 and the positioning of these first sub-beams on the optical axis 56, the embodiment according to Figure 8 comprises two birefringent polarizer elements 62 arranged one behind the other.

[0180] In all other respects, the embodiment according to Figure 8 substantially has the same structure and / or the same operating mode as the embodiment according to Figure 7 and thus in this respect reference is made to the description thereof above.

[0181] As far as the operating mode and design of the beam splitting device 46 is concerned, reference is made to the German patent application with the reference number 102020 207 715.0 (filing date: 22 June 2020) from the same applicant. The entire content of this document is expressly incorporated by reference.

[0182] A further embodiment of the device 10’ for laser machining a workpiece Figure 2 differs from the embodiments described above mainly in that an alternative variant of the telescope device 34’ is provided.

[0183] In the case of the telescope device 34’, the first lens element 36 is integrated in the beam shaping device 16, 16’ or is arranged on the beam exit side 22 of the beam shaping device. This makes it possible for the device 10’ to have, in particular, a particularly compact configuration and / or a configuration with a reduced number of individual components.

[0184] For example, the function of the first lens element 36 is integrated in the beam shaping device 16, 16’.

[0185] The intermediate image 26'' formed in the case of the device 10' and assigned to the focal region 18 does not necessarily have the properties of the intermediate images 26, 26' described above. In comparison with the intermediate images 26, 26', the intermediate image 26'' has a different form due to the modified beam profile in the present example. In particular, the intermediate image 26'' has a different shape in comparison with the intermediate images 26, 26' and / or the focal region 18.

[0186] In all other respects, the device 10' essentially has the same structure and the same mode of operation as the variant of the device 10 described above, and therefore reference is made thereto in this respect.

[0187] For determining the length l of the focal region 18 in the direction of the longitudinal central axis 40 and / or the diameters dx, dy in the x-direction and y-direction, respectively, oriented perpendicular with respect to the longitudinal central axis 28, the modified intensity distribution is considered which has only intensity values above a determined intensity threshold, wherein the intensity threshold is, in particular, 50% of the global intensity maximum of the actual intensity distribution. In Figure 10 a、 Figure 10 b and Figure 10 c schematically show the diameters dx, dy of the focal region 18.

[0188] The length l of the focal region 18 is to be understood, for example, to mean the maximum extension length and / or the maximum extension dimension of the focal region 18 along the longitudinal central axis 40 based on the modified intensity distribution. In Figure 9a In the example shown, the length l is, for example, the corresponding curve length and / or arc length and / or circular arc length of the focal region 18.

[0189] It can be provided that the device 10 comprises a further telescope arrangement 69 which is arranged in the longitudinal direction z between the laser source 12 and the beam shaping arrangement 16, 16'. This further telescope arrangement 69 can be used for controlling and / or adjusting the diameter do of the input laser beam 14 incident on the beam shaping arrangement 16, 16'.

[0190] By controlling and / or adjusting the diameter do, the length l of the focal region and / or the length of the intermediate image 26, 26' of the focal region 18 can be controlled and / or adjusted. The length l increases with increasing diameter do.

[0191] The device 10, 10' according to the application operates as follows:

[0192] For performing a machining operation on the workpiece 70 by means of the device 10, 10', the focal region 18 is applied to the material 72 of the workpiece 70 and the focal region 18 is moved relative to the material 72.

[0193] In particular, material 72 is a material that is transparent or partially transparent to the wavelength of the input laser beam 14 and / or the wavelength of the focusing region 18 formed by the input laser beam 14. For example, material 72 is a glass material.

[0194] The focal zone 18 moves particularly along the predetermined machining line 74 and / or machining surface. Figure 11 , Figure 12a and Figure 12b Processing line 74 may, for example, have straight and / or curved sections.

[0195] By applying the focal region 18 to the material 72, local material modification portions are formed on the material 72 on the processing line 74 and / or processing surface, which reduce the strength of the material 72 on the processing line 74 and / or processing surface.

[0196] This allows material 72 to be separated into two distinct segments, for example, by applying mechanical force after the material modification portion has been formed on the machining line 74 and / or machining surface.

[0197] Figure 11 , Figure 12a and Figure 12b For example, a first variation of the processing of material 72 is shown by means of a focal region 18a, which extends from a first outer side 76 to a second outer side 78 opposite to the first outer side 76, wherein the first outer side 76 and the second outer side 78 are spaced apart from the material thickness D of material 72. In the example shown, the first focal region 18a extends at least over the entire material thickness D. This allows, for example, a segment 80 extending over the entire material thickness D to be separated from material 72.

[0198] The second variant section of the focal region 18b extends through the material 72. This allows, for example, the segment 82 with a quarter-circle profile to be separated from the material 72. Figure 12b The focal region 18b allows, for example, the edge 84 of material 72 to be rounded.

[0199] The focus area 18 is oriented parallel to the feed direction 86 of the material 72 and the machining line 74.

[0200] Figure 13 Multiple modified regions 88 are shown, formed by the relative movement of the focal region 18 with respect to the material 72. In particular, the cross-section of the focal region 18 is oriented such that the long axis of the cross-section is at least approximately parallel to the feed direction 86 and / or the short axis of the cross-section is oriented laterally and, in particular, perpendicularly to the feed direction 86.

[0201] exist Figure 13 In the example shown, the focal region 18 has an elliptical cross-section. A larger semi-axis and / or a larger diameter dy are oriented at least approximately parallel to the feed direction 86.

[0202] This makes it possible to form the cracks 90 between the adjoining modified regions 88, in particular in a controlled manner, which thereby enables optimal separation of the material 72.

[0203] In particular, the cracks 90 are oriented at least approximately parallel to the shortest connecting lines between the adjoining modified regions 88.

[0204] List of reference signs

[0205] β1 cone angle Δx position offset

[0206] Δb position offset Δα angle offset

[0207] dx diameter in x direction

[0208] dy diameter in y direction

[0209] d0 diameter D material thickness

[0210] l length z longitudinal direction

[0211] 10, 10' apparatus 12 laser source

[0212] 14 input laser beam 16, 16' beam shaping device

[0213] 18 focal region 18a, 18b focal region

[0214] 20 beam entry side 22 beam exit side

[0215] 24 sub-beam

[0216] 25 optical axis

[0217] 26, 26', 26'' intermediate image

[0218] 27 longitudinal centre axis

[0219] 28 jump site

[0220] 30a first partial region

[0221] 30b second partial region

[0222] 32a first boundary point

[0223] 32b second boundary point

[0224] 34, 34' telescope device

[0225] 36 first lens element

[0226] 38 second lens element

[0227] 40 longitudinal center axis

[0228] 42 total maximum intensity distribution

[0229] 44 secondary intensity distribution

[0230] 46 beam splitting device

[0231] 48 far field region

[0232] 50 focal plane

[0233] 52 incident beam

[0234] 54a first sub-beam

[0235] 54b second sub-beam

[0236] 56 optical axis

[0237] 58a first sub-focal region

[0238] 58b second sub-focal region

[0239] 60a first longitudinal center axis

[0240] 60b second longitudinal center axis

[0241] 62 birefringent polarizer element

[0242] 64 beam entry side

[0243] 66 optical axis

[0244] 68 isotropic element

[0245] 69 further telescope device

[0246] 70 workpiece

[0247] 72 material

[0248] 74 processing line

[0249] 76 first outer side

[0250] 78 second outer side

[0251] 80 section

[0252] 82 section

[0253] 84 edge

[0254] 86 feed direction

[0255] 88 modified region

[0256] 90 crack

Claims

1. An apparatus for laser processing of a workpiece (70), the apparatus comprising: A beamforming device (16, 16') for forming a focused area (18) from an input laser beam (14) incident on the beamforming device (16, 16'); and a telescope device (34, 34') for imaging the focused area (18) onto the material (72) of the workpiece (70), wherein phase application on the beam cross-section of the input laser beam (14) is achieved by means of the beamforming device (16, 16') such that the focused area ( 18) Extending along a longitudinally curved central axis (40) at least in sections, wherein the telescope device (34, 34') is equipped with a beam splitting device (46) for splitting a sub-beam (24) coupled from the beamforming device (16, 16') into a plurality of polarized sub-beams (54a, 54b), each of the plurality of polarized sub-beams having at least two different polarization states, wherein the telescope device (34, 34') having the beam splitting device (46) is configured as follows: The purpose of focusing the polarized sub-beams (54a, 54b) into a first sub-focusing region (58a) formed by a first sub-beam (54a) having a first polarization state and a second sub-focusing region (58b) formed by a second sub-beam (54b) having a second polarization state is such that the focusing region (18) is formed at least sectionally by the spatial overlap of the first sub-focusing region (58a) and the second sub-focusing region (58b), and the focusing region (18) is oriented perpendicularly to the longitudinal central axis (40). The beam splitting device (46) has an asymmetrical cross-section in the plane, characterized in that the beam splitting device (46) has a birefringent polarizer element (62) by means of which not only a positional offset (Δx) but also an angular offset (Δα) is generated between the first sub-beam (54a) and the second sub-beam (54b) coupled from the beam splitting device (46), wherein the first sub-beam (54a) coupled from the beam splitting device (46) is oriented parallel to the optical axis (56) of the telescope device (34, 34').

2. The device according to claim 1, characterized in that, The first sub-focusing region (58a) extends along the first longitudinal central axis (60a), and the second sub-focusing region (58b) extends along the second longitudinal central axis (60b), wherein the first longitudinal central axis (60a) and the second longitudinal central axis (60b) each have a curved shape at least in sections.

3. The device according to claim 2, characterized in that, The first longitudinal center axis (60a) and the second longitudinal center axis (60b) have a positional offset (Δb) in a direction perpendicular to the orientation of the first longitudinal center axis (60a) and / or the second longitudinal center axis (60b).

4. The device according to any one of claims 1 to 3, characterized in that, The first sub-beam (54a) and the second sub-beam (54b) are relatively incoherent and / or the first sub-beam (54a) and the second sub-beam (54b) do not have a fixed phase relationship with each other.

5. The device according to any one of claims 1 to 3, characterized in that, The beam splitting device (46) is arranged in the far field region (48) of the telescope device (34, 34'), and / or the beam splitting device (46) is arranged at least approximately in the focal plane (50) of the telescope device (34, 34').

6. The device according to any one of claims 1 to 3, characterized in that, The beam splitting device (46) is or includes a beam splitting optical instrument, and / or the beam splitting device (46) has at least one birefringent element.

7. The device according to claim 6, wherein, The beam splitter is a polarization beam splitter.

8. The device according to claim 6, wherein, The at least one birefringent element is a birefringent wedge element.

9. The device according to any one of claims 1 to 3, characterized in that, The incident beam (52) is split into sub-beams (54a, 54b) with different polarization states by means of the beam splitting device (46), wherein the sub-beams (54a, 54b) coupled from the beam splitting device (46) and having different polarization states have an angular offset (Δα).

10. The device according to any one of claims 1 to 3, characterized in that, The longitudinal central axis (40) of the focusing area (18) has at least a radius of curvature of at least 50 μm and / or at most 100 mm in sections, and / or the longitudinal central axis (40) of the focusing area (18) has an average radius of curvature of at least 200 μm and / or at most 2 mm, and / or the focusing area (18) has a length (l) of at least 50 μm and / or at most 20 mm.

11. The device according to claim 10, wherein, The focusing region (18) has a length (l) of at least 500 μm and / or at most 2 mm.

12. The device according to any one of claims 1 to 3, characterized in that, The focusing region (18) has a quasi-non-diffractive beam profile and / or a Bessel-like beam profile.

13. The device according to any one of claims 1 to 3, characterized in that, The focusing area (18) has an elliptical cross-section in a plane that is oriented perpendicularly to the longitudinal central axis (40) of the focusing area (18).

14. The device according to claim 13, characterized in that, The maximum diameter (dx, dy) of the cross-sectional ellipse of the focal region (18) is oriented at least approximately parallel to the feed direction (86), and the workpiece (70) moves relative to the focal region (18) along the feed direction to form a machining line (74) and / or a machining surface.

15. The device according to any one of claims 1 to 3, characterized in that, A laser source (12) is provided for providing the input laser beam (14).

16. The device according to claim 15, wherein, A pulsed laser beam is provided by means of the laser source (12).

17. The device according to claim 16, wherein, The pulsed laser beam is an ultrashort pulse laser beam.

18. The device according to any one of claims 1 to 3, characterized in that, The phase distribution of the sub-beams (24) coupled out on the beam exit side (22) of the beamforming device (16, 16') is asymmetrical.

19. The device according to claim 18, wherein, The phase distribution is non-rotationally symmetric.

20. A method for laser processing of a workpiece (70), wherein a focused area (18) is formed by means of an input laser beam (14) incident on the beam forming apparatus (16, 16'), wherein, The focusing region (18) is imaged onto the material (72) of the workpiece (70) by means of a telescope device (34, 34'), and the beamforming device (16, 16') is used to apply phase to the beam cross-section of the input laser beam (14) such that the focusing region (18) extends along a longitudinal central axis (40) that is at least partially curved. The sub-beam (24) coupled from the beamforming device (16, 16') is split into a plurality of polarized sub-beams (54a, 54b) by means of a beam splitting device (46) associated with the telescope device (34, 34'), which has at least one of two different polarization states. These polarized sub-beams (54a, 54b) are focused onto a first sub-focusing region (58a) formed by a first sub-beam (54a) having a first polarization state and a region formed by a first sub-focusing region (58a) having a first polarization state. In the second sub-focusing region (58b) formed by the second sub-beam (54b) having a second polarization state, the focusing region (18) is formed at least sectionally by the spatial overlap of the first sub-focusing region (58a) and the second sub-focusing region (58b), and the focusing region (18) has an asymmetrical cross-section in a plane oriented perpendicular to the longitudinal central axis (40), characterized in that the beam splitting device (46) has a birefringent polarizer element (62) by means of which not only a positional offset (Δx) but also an angular offset (Δα) is generated between the first sub-beam (54a) and the second sub-beam (54b) coupled from the beam splitting device (46), wherein the first sub-beam (54a) coupled from the beam splitting device (46) is oriented parallel to the optical axis (56) of the telescope device (34, 34').

Images