EP4347171A1

EP4347171A1 - Method and apparatus for laser processing of a workpiece

Info

Publication number: EP4347171A1
Application number: EP22730767.5A
Authority: EP
Inventors: Jonas Kleiner; Tim Hesse; Daniel FLAMM
Original assignee: Trumpf Laser und Systemtechnik GmbH
Current assignee: Trumpf Laser und Systemtechnik GmbH
Priority date: 2021-06-02
Filing date: 2022-05-23
Publication date: 2024-04-10
Also published as: US20240109150A1; KR20240007769A; WO2022253606A1

Abstract

The present invention relates to an apparatus for laser processing of a workpiece (104) by means of a focal zone (106), the workpiece (104) comprising a transparent material (102), the apparatus comprising a beam shaping device (110; 110') for forming the focal zone (106) from an input laser beam (112), the focal zone (106) having an elongate form in relation to a longitudinal axis (108) and the focal zone (106) having, perpendicular to the longitudinal axis (108), an asymmetric cross section (140) with a preferred direction (146), a final control element (184) for changing the preferred direction (146) during the laser processing of the workpiece (104), and a controller (186) for controlling the final control element (184) on the basis of a specified assignment rule in an open and/or closed loop control of the preferred direction (146) during the laser processing of the workpiece (104).

Description

TRUMPF Laser- und Systemtechnik GmbH Johann-Maus-Str. 2 71254 Ditzingen

Method and device for laser machining a workpiece

The invention relates to a device for laser processing a workpiece using a focus zone, the workpiece having a transparent material.

The invention further relates to a method for laser processing a workpiece by means of a focus zone, the workpiece having a transparent material.

EP 3 311 947 B1 discloses a method for laser processing a transparent workpiece such as a glass substrate, the workpiece being processed using a pulsed laser beam which has an elongated focal zone with a non-axisymmetric beam cross section.

DE 10 2020 103 884 A1 discloses a device for adjusting the processing optics of a laser processing machine.

DE 10 2019 128 362 B3 provides a diffractive optical beam-shaping element for impressing a phase distribution on a transverse beam profile of a laser beam.

Processing optics for workpiece processing are known from WO 2020/212175 A1, comprising a birefringent polarizer element for dividing at least one input laser beam into a pair of partial beams polarized perpendicularly to one another, and focusing optics arranged in the beam path after the polarizer element for focusing the partial beams focus zones.

The invention is based on the object of providing a device mentioned at the outset and a method mentioned at the outset, by means of which the formation of material modifications in the material of the workpiece is improved can be controlled in order in particular to realize a separation of the material with a smoother separation surface.

In the case of the device mentioned at the outset, this object is achieved according to the invention in that the device comprises a beam-shaping device for forming the focus zone from an input laser beam, the focus zone being elongate with respect to a longitudinal axis and the focus zone having an asymmetrical cross-section perpendicular to the longitudinal axis with a preferred direction, an adjusting device for changing the preferred direction during the laser processing of the workpiece, and a control device for activating the adjusting device on the basis of a predetermined assignment rule in order to control and/or regulate the preferred direction during the laser processing of the workpiece.

For the laser processing of the workpiece, it is provided that the focus zone is introduced into the material of the workpiece and is moved relative to the material. As a result, material modifications are formed along a processing surface on which the material of the workpiece can in particular be separated.

The preferred direction of the cross section of the focal zone is correlated with a preferred direction of a cross section of material modifications that are formed in the material of the workpiece by means of the focal zone. The preferred direction of the material modifications formed can be controlled by means of a provided control and/or regulation of the preferred direction of the focal zone. As a result, the material modifications can be arranged and designed in such a way that the workpiece can be separated with the smoothest possible separating surface.

In particular, the preferred direction of the focus zone can be used to control a preferred direction of material modifications that can be formed in the material by means of the focus zone, with a main direction of extension of cracks being able to be controlled in particular, which are associated with the respective material modifications. In particular, automated control and/or regulation of the preferred direction is provided by means of the control device.

In particular, the preferred direction of the asymmetrical cross section can be controlled over an angular range between 0° and 360°. For example, the assignment specification includes an assignment that allows the asymmetrical cross section to be controlled in an angular range between 0° and 360°.

For example, the preferred direction of the asymmetrical cross section can be controlled with an angle interval of approximately 1/10° and/or in approximately 1/10° increments.

In particular, the focal zone forms a spatially coherent interaction area which is brought into interaction with the material in order to form material modifications in the material of the workpiece.

In particular, the focal zone means a focused radiation area and in particular a spatially connected radiation area of a laser beam with a specific spatial extent. To determine the spatial dimensions of the focal zone, such as a diameter or a total length, only intensity values of the radiation area that are above a certain intensity threshold are considered. The intensity threshold is selected here, for example, in such a way that values lying below this intensity threshold have such a low intensity that they are no longer relevant for an interaction with the material for the formation of material modifications. For example, the intensity threshold is 50% of a global maximum intensity of the focal zone.

For example, the focal zone has a total length of between 50 pm and 5000 pm.

The beam shaping device is set up to form the focal zone from the input laser beam in an elongated manner and with an asymmetrical cross section, the asymmetrical cross section having a preferred direction. The fact that the focal zone is elongate means in particular that the focal zone extends in the direction of its longitudinal axis and/or that the focal zone is elongated and/or linear in the direction of the longitudinal axis. In particular, the focal zone has the greatest spatial extent in the direction of the longitudinal axis.

The longitudinal axis of the focal zone is in particular oriented parallel to a main propagation direction of a laser beam from which the focal zone is formed.

For example, the longitudinal axis of the focal zone can be curved and/or designed as a curve and/or straight.

The workpiece is, for example, plate-shaped and/or panel-shaped. In particular, during laser processing of the workpiece, the longitudinal axis of the focal zone is oriented parallel or transverse to a thickness direction of the workpiece.

A cross-sectional plane of the asymmetric cross-section of the focal zone is oriented perpendicular to the longitudinal axis of the focal zone.

The preferred direction of the asymmetrical cross section of the focal zone is to be understood in particular as a direction in which the cross section has the greatest spatial extent and/or the greatest diameter.

For example, the cross section of the focal zone is at least approximately designed as an ellipse, with the preferred direction of the cross section corresponding to a direction of a major semi-axis of the ellipse.

The assignment specification, on the basis of which the actuating device is controlled by the control device during the laser processing of the workpiece, is or includes, for example, an assignment table and/or a mathematical function. The assignment rule can, for example, also be or include a constant (offset value). It can be favorable if the control device is set up to align the preferred direction during laser processing at least approximately parallel to a feed direction in which the focus zone for laser processing of the workpiece is moved relative to the workpiece.

As a result, for example, cracks in the material of the workpiece associated with the formation of material modifications can be aligned at least approximately parallel to the feed direction. This results in particular in an overlapping of cracks in adjacent material modifications, which in particular enables a material separation with a smooth separation surface.

In particular, the control device is set up to automatically align the preferred direction during the laser processing of the workpiece.

In particular, it can be provided that the focal zone has a quasi-non-diffractive and/or Bessel-like beam profile. As a result, the focus zone is in particular elongate.

In particular, it can be provided that, in order to form the elongated focal zone and in particular to form the asymmetrical cross section of the elongated focal zone, a transverse phase imprint on a beam cross section of the input laser beam takes place by means of the beam shaping device.

In particular, it can be provided that the beam-shaping device has at least one beam-shaping element for the phase imposition of a transverse phase distribution on a beam cross-section of the input laser beam, the phase distribution being selected in order to make the focal zone elongate, and the at least one beam-shaping element being used in particular as a diffractive optical element and/or is designed as an axicon element.

In particular, the phase distribution is selected in order to form the focal zone with a quasi-non-diffracting and/or Bessel-like beam profile. A transverse direction lies in a plane oriented perpendicularly to the beam axis and/or main propagation direction of the input laser beam.

It can be favorable if the phase distribution is selected in such a way that the focus zone is formed with an asymmetrical cross section by impressing the phase distribution by means of the at least one beam-shaping element. As a result, the focal zone can be formed oblong and with an asymmetrical cross-section, for example, with the same element of the device. A rotation of the at least one beam-shaping element then causes, in particular, a change in the preferred direction of the asymmetrical cross section.

For example, an impressed phase distribution comprises a plurality of angle segments, with mutually adjacent angle segments having different azimuthal segment widths and/or a segment lattice phase difference.

It can be advantageous if the at least one beam-shaping element can be influenced by the adjustment device to change the preferred direction of the focal zone, and/or if the at least one beam-shaping element can be rotated by the adjustment device to change the preferred direction of the asymmetrical cross-section of the focal zone. As a result, the preferred direction can be changed and/or set in a technically simple manner.

For example, the at least one beam-shaping element can be rotated about an axis to change the preferred direction of the asymmetrical cross section, which is parallel or identical to the main propagation direction and/or to the beam axis of the input laser beam incident on the beam-shaping element.

It can be favorable if the beam-shaping device has a polarization beam-splitting element, by means of which partial beams are formed with at least two polarization states that differ from one another, with the focal zone having an asymmetrical by focusing the partial beams Cross section is formed. In particular, this allows the asymmetrical cross section of the focus zone to be formed based on the principle of polarization beam splitting.

In particular, the polarization states are linear polarization states. For example, partial beams with polarization states oriented perpendicularly to one another are formed by means of the polarization beam splitting element.

In particular, the polarization beam splitting element is designed to generate an angular offset and/or a spatial offset between the partial beams with different polarization states.

The polarization beam splitting element is arranged in particular in a far field area and/or in a focal plane of the beam shaping device. In particular, a far-field intensity distribution is formed in this far-field region and/or in this focal plane, which is focused to form the focal zone by means of focusing optics of the beam-shaping device.

A rotation of the polarization beam splitting element causes in particular a change in the preferred direction of the asymmetrical cross section of the focal zone.

It can be advantageous if the polarization beam splitting element can be influenced by the adjustment device to change the preferred direction of the focus zone, and/or if the polarization beam splitting element can be rotated by the adjustment device to change the preferred direction of the asymmetrical cross section of the focus zone.

For example, the at least one polarization beam splitting element can be rotated about an axis to change the preferred direction of the asymmetrical cross section, which is parallel or identical to the main propagation direction and/or to the beam axis of a laser beam incident on the polarization beam splitting element. It can be favorable if the beam-shaping device has a beam diaphragm to form the asymmetric cross-section of the focal zone, by means of which an angular range of a far-field intensity distribution formed by means of the beam-shaping device is blocked, with an unblocked portion of the far-field intensity distribution being used to form the elongated focal zone with an asymmetric cross-section is focused. In particular, focusing optics of the beam-shaping device are provided for focusing the unblocked portion of the far-field intensity distribution.

In particular, a rotation of the beam diaphragm causes a change in the unblocked portion of the far-field intensity distribution and/or a change in the preferred direction of the asymmetrical cross section of the focal zone.

In particular, the beam diaphragm is arranged in a far field area and/or in a focal plane of the beam shaping device.

It can be advantageous if the beam diaphragm can be influenced by means of the adjusting device to change the preferred direction of the asymmetrical cross section of the focal zone, in which case in particular an angular range of the far-field intensity distribution that is blocked and/or not blocked by the beam diaphragm can be changed by means of the adjusting device. Changing the blocked and/or unblocked angular range of the far-field intensity distribution causes a change in the preferred direction of the asymmetrical cross-section in particular.

For example, to change the blocked and/or unblocked angular range of the far-field intensity distribution, the beam stop can be rotated about an axis that is parallel or identical to the main propagation direction and/or to the beam axis of a laser beam incident on the beam stop. In this way, in particular, a change in the preferred direction of the asymmetrical cross section of the focal zone can be brought about.

It can be favorable if a far-field intensity distribution is formed by means of the beam-shaping device, with the focus zone being formed by focusing the far-field intensity distribution and with the for forming the focus zone focused far field intensity distribution can be influenced by means of the adjusting device in order to change the preferred direction of the asymmetrical cross section of the focus zone. The far-field intensity distribution can be influenced, for example, as described above, by means of a beam-shaping element and/or a beam diaphragm of the beam-shaping device.

In particular, the far-field intensity distribution is arranged in a far-field region assigned to the beam-shaping device.

The far-field intensity distribution includes, in particular, a ring structure and/or ring segment structure, which preferably has one or more concentric ring segments. In particular, the ring segments each have the same radius. For example, the ring segments are arranged and/or formed concentrically with respect to a beam axis of a laser beam guided through the beam shaping device.

In particular, those angular regions of the ring structure that are focused to form the focal zone can be influenced and/or defined by means of the adjusting device.

In particular, the beam-shaping device includes focusing optics and/or a telescopic device in order to form the focal zone and/or to introduce the focal zone into the material of the workpiece. For example, the far-field intensity distribution for forming the focal zone can be focused by means of the focusing optics. For example, a laser beam decoupled from a beam-shaping element of the beam-shaping device can be focused by means of the telescopic device to form the focus zone.

In particular, the device comprises a laser source for providing the input laser beam, wherein the input laser beam provided by the laser source is in particular a pulsed laser beam and/or an ultra-short pulsed laser beam. In particular, the device is designed to form the focal zone from the input laser beam and/or from an ultra-short pulse laser beam.

In particular, the focal zone is formed from an ultra-short pulse laser beam or is provided by means of an ultra-short pulse laser beam.

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

In particular, the input laser beam and/or the laser beam from which the focal zone is formed has an average power of at least IW to 1 kW. For example, the laser beam includes pulses with a pulse energy of at least 10 pJ and/or at most 50 mJ. It can be provided that the laser beam comprises individual pulses or bursts, the bursts having 2 to 20 sub-pulses and in particular a time interval of approximately 20 ns.

The fact that the workpiece is formed from a transparent material means in particular that the material of the workpiece is made from a material that is transparent to the input laser beam and/or to a laser beam from which the focal zone is formed.

A transparent material is to be understood in particular as a material through which at least 70% and in particular at least 80% and in particular at least 90% of a laser energy of a laser beam from which the focal zone is formed is transmitted.

In particular, the focal zone interacts with the material of the workpiece through non-linear absorption. In particular, material modifications are formed in the material by means of the focal zone due to non-linear absorption.

In particular, it can be provided that the focus zone is set up to produce material modifications in the material of the workpiece, which with a cracking in the material of the workpiece and/or which are Type III modifications.

The material modifications introduced into transparent materials by ultrashort laser pulses are divided into three different classes, see K. Itoh et al. "Ultrafast Processes for Bulk Modification of Transparent Materials" MRS Bulletin, vol. 31 p.620 (2006): Type I is an isotropic refractive index change; Type II is a birefringent refractive index change; and Type III is a so-called void. The material modification produced depends on the laser parameters of the laser beam from which the focal zone is formed, such as the pulse duration, the wavelength, the pulse energy and the repetition frequency of the laser beam, and on the material properties, such as the electronic structure and the thermal expansion coefficient, as well as on the numerical aperture (NA) of focusing.

The voids (cavities) of the type III modifications can be generated with a high laser pulse energy, for example. The formation of the voids is attributed to an explosive expansion of highly excited, vaporized material from the focus volume into the surrounding material. This process is also known as a micro-explosion. Because this expansion occurs within the bulk of the material, the microblast leaves behind a less dense or hollow core (the void), or submicron or atomic-scale microscopic defect, surrounded by a densified shell of material. Due to the compression at the impact front of the microexplosion, stresses arise in the transparent material, which can lead to spontaneous cracking or can promote cracking.

In one embodiment, the device comprises a detection device for optically detecting an actual preferred direction of the asymmetrical cross section of the focal zone formed, the detection device being or being able to be connected in particular to the control device in a signal-effective manner. In particular, the assignment rule can be determined by means of this detection device, on the basis of which the control device activates the actuating device for controlling and/or regulating the preferred direction.

It can be favorable if the detection device is set up for optical detection of the cross section of the focus zone formed and/or if the detection device is set up for optical detection of a respective cross section of material modifications produced in the material by impingement of the material of the workpiece with the focus zone. In this way, in particular, an actual preferred direction of the cross section of the focal zone formed can be determined as a function of different control signals with which the control device controls the actuating device.

In particular, provision can be made for the control device to include a database and/or for the control device to be assigned a database in which the assignment rule is stored.

For example, the control device includes a memory device and/or the control device is assigned a memory device in which the database with the assignment specification is stored.

In the method mentioned at the outset, the invention provides that the focal zone is formed from an input laser beam by means of a beam shaping device, the focal zone being elongated with respect to a longitudinal axis and the focal zone having an asymmetrical cross section perpendicular to the longitudinal axis with a preferred direction, the preferred direction during the Laser processing of the workpiece is changed or can be changed by means of an adjusting device, and the preferred direction is controlled and/or regulated during laser processing of the workpiece by means of a control device, the control device controlling the adjusting device on the basis of a predetermined assignment rule.

The method according to the invention has in particular one or more features and/or advantages of the device according to the invention. Advantageous embodiments of the method according to the invention have already been explained in connection with the device according to the invention. In particular, the method according to the invention can be carried out using the device according to the invention or the method according to the invention is carried out using the device according to the invention.

In particular, it can be provided that the material of the workpiece is acted upon by the focus zone and the focus zone is moved in a feed direction relative to the material. In this way, in particular, material modifications are formed, which are arranged in the material along a processing surface.

In particular, the focal zone and/or the processing area extend over the entire thickness of the material.

For example, the focus zone is coupled into the material through an outside of the workpiece, with the focus zone in particular being oriented transversely and in particular perpendicularly to this outside.

In particular, it can be provided that the material of the workpiece can be separated or is separated after laser processing has taken place, in particular by applying thermal stress and/or mechanical stress and/or by etching using at least one wet-chemical solution. For example, the etching takes place in an ultrasonically assisted etching bath. The workpiece is separated in particular at the material modifications formed and/or at the processing surface.

It can be favorable if the preferred direction is aligned at least approximately parallel to a feed direction by means of the control device during the laser processing of the workpiece, in which the focal zone for the laser processing of the workpiece is moved relative to the workpiece.

It can be advantageous if an actual preferred direction of the asymmetrical cross section of the focal zone formed is detected as a function of a control signal, with which the Control device controls the actuating device for controlling the preferred direction.

The actual preferred direction is to be understood in particular as a resultant preferred direction and/or an actual preferred direction of the asymmetrical cross section of the focal zone formed, which can be optically detected or is detected in particular by means of a detection device.

It can be advantageous if the actual preferred direction of the asymmetrical cross section of the focus zone formed is varied over a specific range of orientation values and/or with an interval of orientation values by actuating the actuating device by means of the control device in order to define the assignment rule.

For this purpose, in particular, the actuating device is activated by means of the control device with different control signals and in particular control signal values of the control signal.

It can be advantageous if, in order to determine the actual preferred direction, the cross section of the focal zone formed is optically recorded and the preferred direction of the optically recorded cross section is determined. In particular, the actual preferred direction is then determined based on the focal zone formed, which is or can be introduced into the material. For example, the actual preferred direction is determined by optical and/or automated evaluation of the recorded cross section, in particular by means of image recognition and/or image data analysis.

It can be favorable if, in order to determine the actual preferred direction, a preferred direction of a respective cross section of one or more material modifications is determined, which were produced in the material by subjecting the material of the workpiece to the focal zone.

In particular, the actual preferred direction is then determined based on a resulting interaction of the focus zone formed with the material of the workpiece. For example, the actual preferred direction is determined by optical and/or automated evaluation of the detected cross section of the material modification, in particular by means of image recognition and/or image data analysis.

It can be advantageous if the corresponding material modification is detected optically in order to determine the preferred direction of the cross section of a specific material modification.

In particular, it can be provided that the actual preferred direction of the cross section of a specific material modification is determined by optically detecting cracks which are assigned to this material modification. For example, a main extension direction of the cracks is determined to determine the preferred direction.

It has been shown that the preferred direction of the cross section of the material modifications actually formed can deviate from the actual preferred direction of the optically recorded cross section of the focal zone formed. The cause can be secondary maxima or optical aberrations around the asymmetrical focal zone. Deviations can also result from preferred directions of the material of the workpiece to be processed, e.g. in the case of a crystalline material. By determining the actual preferred direction on the basis of the preferred direction of the cross section of material modifications, which were produced by subjecting the material of the workpiece to the focal zone in the material, a particularly good controllability and reproducibility of the preferred direction of the formed material modifications and in particular the cracks of the formed Get material mods.

In particular, provision can be made for the assignment rule to be determined and/or adapted and/or optimized before, during or after the laser processing of the workpiece.

In particular, a part of the device referred to as an element in this application, such as a beam-shaping element or a polarization beam-splitting element, can each comprise a plurality of sub-components and/or sub-elements. In particular, the terms “at least approximately” or “approximately” generally mean a deviation of at most 10%. Unless otherwise stated, the terms “at least approximately” or “approximately” mean in particular that an actual value and/or distance and/or angle deviates by no more than 10% from an ideal value and/or distance and/or angle , and/or that an actual geometric shape deviates from an ideal geometric shape by no more than 10%.

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

Show it:

Fig. 1 is a schematic representation of an embodiment of a

Device for laser machining a workpiece;

FIG. 2 shows a schematic representation of a further exemplary embodiment of a device for laser machining a workpiece; FIG.

3a shows a simulated intensity distribution of an asymmetric

Cross-section of a focal zone for laser processing of the workpiece;

3b shows a schematic representation of the intensity distribution of the asymmetrical cross section of the focal zone;

4 shows a schematic sectional view of material modifications in a material of the workpiece, the material modifications being produced by subjecting the material to the focal zone;

FIG. 5a shows a transverse phase distribution associated with the intensity distribution according to FIG. 3a on a beam output side of a beam-shaping element of the device; FIG. 5b shows a transverse far-field intensity distribution assigned to the intensity distribution according to FIG. 3a, the focal zone being formed by focusing this transverse far-field intensity distribution;

Fig. 6 is a schematic cross-sectional view of a

Exemplary embodiment of a polarization beam splitting element for the formation of partial beams with mutually different polarization states;

Fig. 7 is a schematic cross-sectional view of a

Detection device for the optical detection of an actual preferred direction of the asymmetrical cross section of the focal zone formed;

8 shows a schematic representation of a detection device for the optical detection of a cross section of material modifications in the material of the workpiece, which are formed by impinging on the material with the focal zone;

9a shows a micrograph of material modifications arranged in the material of the workpiece, which are produced by subjecting the material to the focal zone; and

FIG. 9b shows a detailed view of partial area A according to FIG. 9a.

Identical or functionally equivalent elements are provided with the same reference symbols in all figures.

An exemplary embodiment of a device for laser machining a workpiece is shown in FIG. 1 and is denoted by 100 there. The device 100 can be used to produce localized material modifications in a material 102 of the workpiece 104, such as defects in the submicrometer range or at the atomic level, which result in a material weakening to have. The workpiece 104 can be separated at these material modifications. For example, a workpiece segment can be separated from the workpiece 104 by means of the material modifications formed.

A focal zone 106 is formed by means of the device 100 and is applied to the material 102 of the workpiece 104 to form material modifications. The focus zone 106 extends along a longitudinal axis 108. The focus zone 106 is elongated and/or elongated parallel to the longitudinal axis 108.

In particular, the focal zone 106 comprises a plurality of focal points adjacent to one another or is formed from a plurality of focal points adjacent to one another.

The workpiece 104 is, for example, plate-shaped and/or panel-shaped. For example, the workpiece 104 has a thickness D which, in particular, is at least approximately constant.

The workpiece 104 is made of a transparent material 102, i.e. the material 102 is transparent to a wavelength of a laser beam by means of which the focal zone 106 is formed.

In particular, the longitudinal axis 108 of the focal zone 106 is oriented parallel or transverse to a thickness direction of the thickness D of the workpiece 104 . For example, the focus zone 106 extends at least over the entire thickness D of the workpiece 104 and/or a workpiece segment to be separated. A total length of the focal zone 106 oriented parallel to the longitudinal axis 108 is, for example, greater than or equal to the total thickness D of the workpiece 104 and/or a workpiece segment to be separated.

To form the focal zone 106, the device 100 comprises a beam shaping device 110. An input laser beam 112, which is provided by a laser source 114, for example, is coupled into this beam shaping device 110. This input laser beam 112 has a Wavelength for which the material 102 of the workpiece 104 is transparent.

This input laser beam 112 is in particular a pulsed laser beam and in particular an ultra-short pulsed laser beam. For example, the input laser beam 112 is a Gaussian beam and/or has a Gaussian beam profile.

After being coupled into the beam-shaping device 110 , the input laser beam 112 propagates through the beam-shaping device 110 and is coupled out of the beam-shaping device 110 as a focused output laser beam 113 . The output laser beam 113 forms the focal zone 106 with which the material 102 of the workpiece 104 is impinged.

The part of the input laser beam 112 that propagates through the beam shaping device 110 is referred to below as the laser beam 116 .

The laser beam 116 has a main propagation direction 118 with which it propagates through the beam shaping device 110 . The main direction of propagation 118 is in particular oriented parallel to a beam axis 120 of the laser beam 116 . This beam axis 120 is to be understood in particular as a longitudinal central axis of the laser beam 116 .

In order to shape the beam of the laser beam 116, the beam-shaping device 110 comprises a beam-shaping element 121, which is embodied, for example, as a diffractive optical element and/or as an axicon element. In principle, it is also possible for the beam-shaping element 121 to be designed as a refractive or reflective element.

The beam-shaping element 121 is not necessarily limited to a single element and/or component. In principle, the beam-shaping element 121 can comprise a plurality of sub-elements and/or sub-components. Beam-shaping element 121 applies a phase to a transverse beam cross-section 122 of input laser beam 112 and/or laser beam 116, the phase imprint being such that laser beam 116 coupled out of beam-shaping element 121 has a quasi-non-diffracting and/or Bessel-like beam profile.

With regard to the definition and properties of quasi-non-diffracting rays, reference is made to the book "Structured Light Fields: Applications in Optical Trapping, Manipulation and Organisation", M. Wördemann, Springer Science & Business Media (2012), ISBN 978-3-642-29322- 1 and the scientific publication "Bessel-like optical beams with arbitrary trajectories" by I. Chremmos et al., Optics Leiters, Vol. 23 , December 1, 2012.

With regard to the formation and properties of quasi-non-diffractive and/or Bessel-like beams with an asymmetrical cross-section, reference is made to the scientific publication "Generalized axicon-based generation of non-diffracting beams" by K. Chen et al., arXiv: 1911.03103vl [physics. optics],

November 8, 2019, referenced.

A transverse direction is to be understood as meaning a direction which lies in a plane oriented perpendicularly to the main propagation direction 118 and/or to the beam axis 120 .

Provision can be made for the beam-shaping device 110 to have adjustment optics 124 for adjusting a diameter do of the beam cross section 122 . By adjusting the diameter do of the laser beam 116 incident on the beam-shaping element 121, the overall length of the focal zone 106 can be adjusted in particular. For example, the adjustment optics 124 is designed as a telescope or includes a telescope.

The adjustment optics 124 are arranged in front of the beam-shaping element 121 with respect to the main propagation direction 118 . The beam shaping device 110 includes focusing optics 126 in order to focus the laser beam 116 coupled out of the beam shaping element 121 in order to form the focal zone 106 .

The focusing optics 126 include, for example, one or more lens elements 127. For example, the focusing optics are designed as an objective.

In particular, the focusing optics 126 are part of a telescope device 128 of the beam shaping device 110 , the laser beam 116 coupled out of the beam shaping element 121 being focused into the focal zone 106 by means of this telescope device 128 .

In the exemplary embodiment according to FIG. 1, the telescope device 128 comprises lens optics 129 arranged at a distance from the focusing optics 126. This lens optics 129 is or comprises, for example, at least one lens element 130, which is designed, for example, as a converging lens.

With respect to the main propagation direction 118, the lens optics 129 are arranged in front of the focusing optics 126 and/or arranged between the beam-shaping element 121 and the focusing optics 126.

The lens optic 129 has a first focal length fi and the focusing optic 126 has a second focal length f2, the first focal length fi being greater than the second focal length f2.

A focal plane 132 is assigned to the focusing optics 126 and/or the telescope device 128 . This focal plane is positioned in a far-field region 134 associated with the focusing optics 126 and/or the telescope device 128 .

In particular, the focal plane 132 and/or the far-field region 134 are positioned between the lens optics 129 and the focusing optics 126 with respect to the main propagation direction 118 . The focal plane 132 is in particular a common focal plane of the lens optic 129 and the focusing optic 126. For example, the focal plane 132 is spaced from the lens optic 129 with the first focal length fi and is spaced from the focusing optic 126 with the second focal length f2.

In the embodiment of the beam-shaping device 110 shown in Fig. 1, an intermediate image 136 assigned to the focal zone 106 is formed, for example, which is arranged behind the beam-shaping element 121 and/or between the beam-shaping element 121 and the focusing optics 126, in particular with respect to the main propagation direction 118.

A further embodiment of a beam-shaping device 110′ shown in FIG. 2 differs from the embodiment of the beam-shaping device 110 described above essentially in that the lens optics

129 is integrated into the beam-shaping element 121 and/or forms a unit with the beam-shaping element 121.

For example, a functionality of lens optics 129 is integrated into beam-shaping element 121 . For example, the phase distribution impressed on the beam cross-section 122 by means of the beam-shaping element 121 is adapted for the integration of the lens optics 129 in the beam-shaping element 121 .

It can be provided that the lens optics 129 and/or a lens element

130 of the lens optics 129 is arranged on a beam exit side 138 of the beam shaping element 121 .

Otherwise, the beam-shaping device 110′ basically has the same structure and the same mode of operation as the beam-shaping device 110, so that in this respect reference is made to its description.

In particular, the beam shaping device 110 ′ has one or more further features and/or advantages of the beam shaping device 110 . The focal zone 106 formed by means of the beam shaping device 110 has an elongated and/or elongate shape with respect to its longitudinal axis 108 . This is realized by the phase imprinting by means of the beam-shaping element 121, with the phase imprinting by means of the beam-shaping element 121 in particular generating a quasi-non-diffracting and/or Bessel-like beam profile.

Furthermore, a cross section 140 of the focal zone 106 is asymmetrical, with a cross-sectional plane assigned to the cross section 140 being oriented perpendicularly to the longitudinal axis 108 .

A simulated intensity distribution of the asymmetrical cross-section 140 of the focal zone 106 is shown, for example, in FIG. 3a in the form of a gray scale representation. In this grayscale representation, lighter areas represent areas of higher intensities.

A modified intensity distribution is used to determine spatial dimensions of focal zone 106, such as its overall length in the direction of longitudinal axis 108 and/or a diameter dx, d _y of cross section 140 in an x-direction or y-direction oriented perpendicularly to longitudinal axis 108 considered, which only has intensity values that are above a certain intensity threshold. In particular, this intensity threshold is 50% of a global intensity maximum of the actual intensity distribution. This is illustrated schematically in FIG. 3b for the diameters dx, d _y of the cross section 140 of the focal zone 106 .

The total length of the focus zone is to be understood, for example, as a maximum extension length and/or a length of maximum extension of the focus zone 106 along the longitudinal axis 108 based on the modified intensity distribution mentioned. Correspondingly, the diameter dx or d _y is to be understood as meaning a maximum extension length and/or a length of maximum extension of the cross section 140 of the focal zone 106 in the x-direction or y-direction. The focal zone 106 is to be understood in particular as a global maximum intensity distribution 142 which is in particular spatially coherent. In particular, only this global maximum intensity distribution 142 is relevant for an interaction with the material 102 of the workpiece 104 for the formation of material modifications.

The maximum intensity distribution 142 is in particular surrounded by secondary intensity distributions 144 . These secondary intensity distributions 144 are in particular arranged around the maximum intensity distribution 142 and/or arranged at a distance from the maximum intensity distribution 142 . The secondary intensity distributions 142 are or include, in particular, secondary maxima.

In particular, the secondary intensity distributions 144 are insignificant for the laser processing of the workpiece 104, since their lower intensities result in no and/or negligible formation of material modifications in the material 102.

The asymmetrical cross section 140 of the focal zone 106 has a preferred direction 146 which lies in a plane oriented perpendicular to the longitudinal axis 108 of the focal zone 106 . In particular, the preferred direction 146 is to be understood as meaning a direction in which the asymmetrical cross section 140 has the greatest spatial extent and/or the greatest diameter.

In the example shown in FIGS. 3a and 3b, the largest spatial extent and/or the largest diameter of the cross section 140 are oriented parallel to the x-direction. Correspondingly, the preferred direction 146 is oriented parallel to the x-direction and/or parallel to a direction of the diameter dx.

In particular, cross section 140 is elliptical and/or at least approximately embodied as an ellipse. The preferred direction 146 then corresponds, for example, to a direction of a major semi-axis of the ellipse. For example, the diameter dx is then oriented parallel to the major semi-axis and the diameter d _y is oriented parallel to the minor semi-axis. For the laser processing of the workpiece 104, its material 102 is acted upon by the focal zone 106 and the focal zone 106 is moved in a feed direction 148 relative to the material 102 (FIG. 4).

By subjecting the material 102 to the focal zone 106, material modifications 150 are formed in the material 102, which are arranged and/or lined up along the longitudinal axis 108 of the focal zone 106.

By moving the focal zone 106 relative to the material 102, material modifications 150 spaced apart in the feed direction are formed. A distance between mutually adjacent material modifications 150 parallel to the feed direction 148 depends in particular on a feed speed at which the focal zone 106 is moved in the feed direction 148 relative to the material 102 .

Due to the loading of the material 102 with an elongate focal zone 106 and its movement relative to the material 102, material modifications 150 are formed along a processing surface along which the material 102 in particular can be separated. Material can be separated along the processing surface, for example, by exerting a mechanical force.

The material modifications 150 have a cross section 152 which has a shape corresponding to the cross section 140 of the focal zone 106 . A cross-sectional plane assigned to cross section 152 is oriented perpendicularly to longitudinal axis 108 and/or parallel to feed direction 148 of focal zone 106 with which corresponding material modification 150 was formed.

Furthermore, the cross section 152 of a specific material modification 150 has a preferred direction 154 which corresponds to the preferred direction 146 of the cross section 140 of that focal zone 106 with which the material modification 150 was formed. In particular, the material modification 150 has the greatest spatial extent and/or the greatest diameter in the direction of the preferred direction 154 . In the example shown in FIG. 4, the cross section 152 is designed as an ellipse and the preferred direction 154 corresponds to a direction of a major semi-axis of the ellipse.

In particular, the laser parameters assigned to the focal zone 106 are selected such that the material modifications 150 formed in the material 102 by means of the focal zone 106 are accompanied by the formation of cracks 156 in the material 102 . For example, Material Mods 150 are Type III Mods.

The cracks 156 extend in particular between adjacent material modifications 150 which are spaced apart from one another in the feed direction 148 . In particular, cracks 156 extend along a main extension direction 158, which are oriented at least approximately parallel to preferred direction 154 of material modification 150 associated with these cracks 156 and/or are oriented at least approximately parallel to preferred direction 146 of focal zone 106, by means of which these Cracks 156 associated material modification 150 was formed.

The main extension direction 158 is to be understood in particular as an average and/or averaged extension direction of the cracks 156 associated with a specific material modification 150 .

The beam-shaping device 110 comprises at least one preferred direction beam-shaping element 160 for forming the asymmetrical cross-section 140 of the focal zone 106 with the preferred direction 146. In particular, the preferred direction beam-shaping element 160 can be changed, preferably in a plane oriented perpendicularly to the longitudinal axis 108 of the focal zone 106 and/or adjustable.

It can be provided that the preferred direction beam-shaping element 160 and/or a functionality of the preferred direction beam-shaping element 160 is integrated into the beam-shaping element 121 . For example, the asymmetrical cross section 140 of the focal zone 106 is realized by the phase imprinting taking place by means of the beam-shaping element 121 .

The formation of a focus zone with an asymmetrical cross-section through phase imprinting is known, for example, from DE 10 2019 128 362 B3.

FIG. 5a shows an example of a transverse phase distribution which is impressed on the beam cross section 122 by means of the beam shaping element 121 in order to form the focal zone 106 with an asymmetrical cross section 140 . For example, laser beam 116 is coupled out at beam output side 138 of beam-shaping element 121 with this phase distribution.

For example, the phase distribution has a plurality of angle segments 162a, 162b, wherein mutually adjacent angle segments have different azimuthal segment widths Dbi, Db2 and/or have a segment lattice phase difference.

An example of a far-field transverse intensity distribution 164 formed in the focal plane 132 and/or the far-field region 134 of the beam-shaping device 110 is shown in FIG. 5b. This far-field intensity distribution 164 results from the phase imprinting performed by means of the beam-shaping element 121 .

The far-field intensity distribution 164 includes a ring structure. In this embodiment, the ring structure is designed in particular as a ring segment structure and/or comprises a plurality of ring segments 166 which are arranged in particular concentrically with respect to the beam axis 120 . In particular, all ring segments 166 of the ring structure have the same radius.

The ring structure of the far-field intensity distribution 164 includes one or more discontinuities 168 located between adjacent ring segments 166 . These interruptions 168 extend in particular in one or more azimuthal angular ranges ring structure. In particular, the intensity at these interruptions 168 is zero or the intensity is at least 90% less than an intensity of the adjacent ring segments 166.

The focal zone 106 is formed by focusing the far-field intensity distribution 164 by means of the focusing optics 126 and/or by means of the telescopic device 128 . Due to the ring structure with the interruptions 168, the focal zone 106 is formed with an asymmetrical cross section 140. FIG.

In this case, the preferred direction 146 of the asymmetrical cross section 140 can be changed and/or set, for example, by rotating the beam-shaping element 121 , with an axis of rotation being oriented in particular parallel to the beam axis 120 or corresponding to the beam axis 120 .

In a further specific embodiment, it is provided that the preferred direction beam-shaping element 160 is or includes a beam stop 170 in order to form the focal zone 106 with an asymmetrical cross section 140 . The beam stop 170 is configured to block one or more angular ranges of the ring structure of the far-field intensity distribution 164 , the blocked angular ranges of the ring structure in particular not being focused by means of the focusing optics 126 .

The beam diaphragm 170 is arranged in particular in the far-field region 134 and/or in the focal plane 132 .

For example, in this embodiment, the beam-shaping element 121 is designed to form the far-field intensity distribution 164 with a ring structure, which has a continuous and/or uninterrupted ring. Resulting interruptions 168 are then produced on this ring structure by blocking angular areas of the ring structure using the beam stop 170 . As a result, the ring structure focused by means of the focusing optics 126 then has, for example, the structure shown in FIG. 5b.

The preferred direction 146 of the asymmetrical cross-section 140 can be in this embodiment, for example, by changing the means of Change beam diaphragm 170 blocked angular areas of the ring structure of the far-field intensity distribution and / or adjust. For example, the blocked angular ranges can be changed by adjusting and/or rotating the beam stop 170, with an axis of rotation preferably being oriented parallel to or coincident with the beam axis 120.

In a further embodiment, it is provided that the preferred direction beam-shaping element 160 is or comprises at least one polarization beam-splitting element 172, an exemplary embodiment of the polarization beam-splitting element 172 being shown in FIG. The polarization beam splitting element 172 is arranged in particular in the far-field region 132 and/or in the focal plane 132 .

The laser beam 116 incident on the polarization beam splitting element 172 is split by means of the polarization beam splitting element 172 into mutually different sub-beams 174a, 174b with different polarization states.

In particular, the stated polarization states are to be understood as meaning linear polarization states, with two different polarization states being provided, for example, and/or polarization states oriented perpendicularly to one another being provided.

In particular, beams coupled out of the polarization beam splitting element 172 are polarized in such a way that an electric field is oriented in a plane perpendicular to the main propagation direction 118 (transversally electric).

The partial beams 174a, 174b have a spatial offset Dc and an angular offset Da, with one of the partial beams 174a, 174b in particular being oriented parallel to the beam axis 120 of the incident laser beam or coinciding with it.

For example, the polarization beam splitting element 172 comprises a birefringent polarizer element 176 and an isotropic element 178, which is arranged in particular behind the polarizer element 176 with respect to the main propagation direction 118. The polarizer element 176 and/or the isotropic element 178 are wedge-shaped, for example.

With regard to the functioning and design of the polarization beam splitting element 128, reference is made to the German patent application with file number 10 2020 207 715.0 (filing date: June 22, 2020) by the same applicant and to DE 10 2019 217 577 A1.

An optical axis 180 of polarizer element 176 is oriented, for example, at an angle of at least approximately 45° to a beam input side 182 of polarizer element 176 and/or to beam axis 120 .

After focusing by means of the focusing optics 126, the polarized partial beams 174a, 174b have a spatial offset. In particular, the partial beams 174a, 174b are focused in different partial areas of the focal zone 106, which overlap at least in sections. As a result, the focal zone 106 can be formed with an asymmetrical cross section 140 .

In this embodiment, the preferred direction 146 of the asymmetrical cross section 140 can be changed and/or set, for example, by rotating the polarization beam splitting element 172, preferably about the beam axis 120 or about an axis parallel to the beam axis 120.

The device 100 includes an adjusting device 184, by means of which the preferred direction 146 of the asymmetrical cross section 140 of the focal zone 106 can be changed during the laser processing of the workpiece 104. A change and/or setting of the preferred direction 146 is to be understood in particular as meaning that an orientation of the preferred direction 146 in a plane oriented perpendicular to the longitudinal axis 108 of the focal zone 106 is changed or set.

To change the preferred direction 146, the adjusting device 184 influences the preferred direction beam-shaping element 160, such as the beam-shaping element 121 and/or the beam stop 170 and/or the Polarization beam splitting element 172. In particular, the preferred direction beam shaping element 160 can be moved and/or rotated by means of the adjusting device 184 in order to change the preferred direction 146.

The device 100 further includes a control device 186 which is connected to the actuating device 184 in a signal-effective manner.

It is provided that the actuating device 184 is actuated by means of the control device 186 on the basis of an assignment specification. This assignment rule is stored in particular in a database 188 which is included in the control device 186 or to which the control device 186 is connected in a signal-effective manner.

During operation of the device 100, the preferred direction 146 is controlled by the control device 186 in particular in such a way that the preferred direction 146 is oriented parallel or approximately parallel to the feed direction 148. For this purpose, the control device 186 controls the setting device 184 on the basis of the assignment rule with a control signal in order to bring about the corresponding orientation of the preferred direction 146 .

The assignment rule is or includes an assignment table, for example, which contains an assignment of control signal values of the control signal to orientation values of the preferred direction 146 .

The orientation values of the preferred direction 146 can be specified, for example, as angle information of an angle Q to a reference direction 190 , the reference direction 190 lying in a plane oriented perpendicularly to the longitudinal central axis 108 .

The device 100 comprises a detection device 192, by means of which an actual preferred direction 194 (indicated in FIG. 7) of the cross section 140 of the focus zone 106 formed can be optically detected. The actual preferred direction 194 is to be understood, in particular, as an actual preferred direction of the cross section 140 as it is present, for example, in the material 102 and/or as determined by the detection device 192 .

In the example shown in FIG. 7 , the focus zone 106 is formed by means of the beam shaping device 110 and the work piece 104 is acted upon by the focus zone 106 . The focal zone 106 formed is optically detected by the detection device 192 .

For the optical detection of the formed focal zone 106, the detection device 192 comprises, in particular, an image recording device 196, which has an image sensor and/or a camera, for example. Furthermore, the detection device 192 comprises, in particular, imaging optics 198 in order to image the focal zone 106 formed by means of the beam shaping device 110 onto the image recording device 196 .

With respect to the main propagation direction 118 of the output laser beam 113 coupled out of the beam shaping device 110, the detection device 192 is arranged in particular behind the workpiece 104 and/or the focus zone 106 that has been formed.

The actual preferred direction 194 can be determined by evaluating image data recorded by means of the image recording device 196 , it being possible for the evaluation to be carried out by means of the control device 186 , for example. In particular, the detection device 192 is then connected to the control device 186 in a signal-effective manner.

A further embodiment of an optical detection device 192' is shown in FIG. 8 and differs from the detection device 192 described above essentially in that, in the case of the detection device 192', a material modification 150 formed in the material 102 of the workpiece 104 by means of the focal zone 106 is optically detected in order to determine their preferred direction 154 (cf. FIG. 4). Otherwise, the detection device 192′ has, in particular, one or more features and/or advantages of the detection device 192, so that reference is made to its above description in this respect.

In this embodiment, by detecting the preferred direction 154 of the cross section 152 of a material modification 150 formed by means of the focal zone 106, the actual preferred direction 194 of the focal zone 106 with which this material modification 150 was formed is inferred. Within the scope of this embodiment, the preferred direction 154 of the assigned material modification 150 corresponds to the actual preferred direction 194 and/or the actual preferred direction of the focal zone 106, by means of which this material modification 150 was formed.

The detection device 192 ′ includes, for example, the image recording device 196 and imaging optics 198 ′ in order to image the material modification 150 onto the image recording device 196 . In particular, the cross section 152 of the material modification 150 and/or the cracks 156 associated with the material modification 150 are optically recorded by means of the image recording device 196 .

The preferred direction 154 and/or the actual preferred direction 194 can be determined by evaluating image data recorded by means of the image recording device 196 . Provision can be made for the main extension direction 158 of cracks 156, which are associated with this material modification 150, to be used to determine the actual preferred direction 194 of a specific material modification 150.

In the exemplary embodiment according to FIG. 8, the material modifications 150 formed in the material 102 are detected in reflected-light microscopy.

For example, the focusing optics 126 of the beam-shaping device 110 serve as the objective of the imaging optics 198'. The rays incident from the workpiece 104 onto the focusing optics 126 are deflected in the direction of the image recording device 196, for example by means of a partially reflecting element 200 of the imaging optics 198'. Exemplary micrographs of the material 102 with material modifications 150 formed therein are shown in FIGS. 9a and 9b, the material modifications 150 being arranged in a circle in the example shown.

In particular, the main extension direction 158 of the cracks 156 of an associated material modification corresponds at least approximately to the preferred direction 154 of the cross section 152 of this material modification.

The device 100 works as follows:

In order to determine the assignment specification, on the basis of which the control and/or regulation of the preferred direction 146 takes place by means of the control device 186, the actuating device 184 is actuated by the control device 186 with different control signal values, for example, and the actual preferred direction 194 is determined for each of the different control signal values. The actual preferred direction 194 is determined here by means of the detection device 192, 192'.

As a result, the assignment rule is determined in the form of a relationship between different control signal values and orientation values of the actual preferred direction 194 . In particular, the assignment specification contains the information with which control signal value the actuating device 184 must be controlled in order to realize a specific actual preferred direction 194 .

In the case of detection device 192, the actual preferred direction 194 is determined, for example, by optically detecting and evaluating the cross section 140 of the focal zone 106 formed by the beam shaping device 110. The optical detection of the cross section 140 of the focal zone 106 can, for example, be inside or outside the material 102 of the workpiece 104 take place. For example, the cross section 140 is recorded in air. In the case of the detection device 192', the actual preferred direction 194 is determined, for example, by optical detection and evaluation of the cross section 152 of material modifications 150, which are or were formed by means of the focal zone 106 with different control signal values.

For example, several material modifications 150 are shown in FIG. 9 b , which are arranged at different positions in the material 102 of the workpiece 104 and were formed with different control signal values or preferential directions 146 . The actual preferred direction 194 is determined, for example, by optically detecting and evaluating the material modifications 150 formed in the material 102, whereby to determine the actual preferred direction 194 of a specific material modification, in particular its cross section 152 and/or the main direction of extension 158 of this material modification 150 are associated with cracks 156 is optically recorded and/or evaluated.

In principle, the assignment rule can be determined before or during the laser processing of the workpiece 104 .

To carry out the laser processing, the material 102 of the workpiece 104 is acted upon by the focal zone 106 and the focal zone 106 is moved in the feed direction 148 relative to the workpiece 104 through its material 102 .

The material 102 is a material that is transparent to a wavelength of the input laser beam 112 and/or the laser beam 116 from which the focal zone 106 is formed by means of the beam shaping device 110 . For example, material 102 is a glass material such as fused silica.

By moving the focal zone 106 relative to the material 102, material modifications 150 are formed, which are arranged along a processing surface as described above. The distance from material modifications 150 that are adjacent in the feed direction 148 can be defined, for example, by setting a pulse duration of the input laser beam 112 and/or by setting the feed rate.

The material modifications 150 formed along the processing surface result in particular in a reduction in the strength of the material 102 . As a result, the material 102 can be separated into two different workpiece segments after the material modifications 150 have formed on the processing surface, for example by exerting a mechanical force.

It is advantageous if the preferred direction 146 of the asymmetrical cross section 140 of the focal zone 106 is aligned parallel or approximately parallel to the feed direction 148 during the laser processing of the workpiece 104 . This results in a smoother separating surface when the workpiece 104 is separated along the processing surface.

In the case of the material modification 150a shown in FIG. 9b, the feed direction 148 was not oriented approximately parallel to the feed direction 148 when this material modification 150a was formed. In particular, the main extension direction 158 of the cracks 156 associated with the material modification 150a is then not oriented approximately parallel to the feed direction 148 either. Unevenness can result when the workpiece is separated.

In particular, it is therefore provided that the preferred direction 146 is controlled and/or regulated by the control device 186 in such a way that the preferred direction 146 is oriented parallel or approximately parallel to the feed direction 148 during the laser processing of the workpiece 104 . Cracks 156 in adjacent material modifications 150 then merge into one another at least approximately continuously and/or without interruption, so that in particular the workpiece can be separated with a smooth separating surface (see, for example, partial area 202 identified in FIG. 9a). Reference List

Since angular misalignment

Dbi azimuthal segment width

Db ₂ azimuthal segment width

D thickness dx diameter in x-direction d _y diameter in y-direction fi first focal length f ₂ second focal length

Q angle

Dc offset

100 device

102 materials

104 workpiece

106 focus zone

108 longitudinal axis

110 beam shaping device

110' beam shaping device

112 input laser beam

113 output laser beam

114 laser source

116 laser beam

118 main propagation direction

120 beam axis

121 beam shaping element

122 beam cross-section

124 customization optics

126 focusing optics

127 lens element

128 Telescope device

129 lens optics

130 lens element

132 focal plane far field range

intermediate image

beam exit side

Cross section maximum intensity distribution secondary intensity distribution

preferred direction

feed direction

Material modification a Material modification

cross-section

preferred direction

Crack

Main extension direction

Preferred direction beam-shaping elementa angular segment b angular segment

Far-field intensity distribution

ring segment

interruption

beam stop

Polarization beam splitting element a sub-beam b sub-beam

polarizer element isotropic element optical axis

beam entrance side

adjusting device

control device

Database

reference direction

Detection device ' detection device actual preferred direction Image recording device 'imaging optics partially reflecting element section

Claims

patent claims

1. A device for laser processing a workpiece (104) by means of a focus zone (106), wherein the workpiece (104) has a transparent material (102), comprising

- a beam shaping device (110; 110') for forming the focal zone (106) from an input laser beam (112), wherein the focal zone (106) is elongate with respect to a longitudinal axis (108) and wherein the focal zone (106) is perpendicular to the longitudinal axis (108 ) has an asymmetrical cross section (140) with a preferred direction (146),

- an adjusting device (184) for changing the preferred direction (146) during the laser processing of the workpiece (104), and

- A control device (186) for controlling the actuating device (184) on the basis of a predetermined assignment specification in order to control and/or regulate the preferred direction (146) during the laser processing of the workpiece (104).

2. Device according to claim 1, characterized in that the control device (186) is set up to align the preferred direction (146) during the laser processing at least approximately parallel to a feed direction (148) in which the focus zone (106) for the laser processing of the workpiece (104) is moved relative to the workpiece (104).

3. Device according to one of Claims 1 or 2, characterized in that the beam shaping device (110; 110') has at least one beam shaping element (121) for phase impressing a transverse phase distribution on a beam cross section (122) of the input laser beam (121), the phase distribution is selected in order to form the focal zone (104) in an elongate manner, and wherein the at least one beam-shaping element (121) is formed in particular as a diffractive optical element and/or as an axicon element.

4. Device according to one of the preceding claims, characterized in that the phase distribution is selected such that the focal zone (104) with an asymmetrical cross section (140) is formed by impressing the phase distribution by means of the at least one beam-shaping element (121).

5. The device according to claim 4, characterized in that the at least one beam-shaping element (121) can be influenced by means of the adjusting device (184) to change the preferred direction (146) of the focal zone (106), and/or that the at least one beam-shaping element (121) can be rotated by means of the adjusting device (184) to change the preferred direction (146) of the asymmetrical cross section (140) of the focal zone (106).

6. Device according to one of the preceding claims, characterized in that the beam shaping device (110; 110 ') has a polarization beam splitting element (172), by means of which partial beams (174a, 174b) are formed with at least two mutually different polarization states, wherein by focusing of the partial beams (174a, 174b), the focal zone (106) is formed with an asymmetrical cross section.

7. The device according to claim 6, characterized in that the polarization beam splitting element (172) can be influenced by means of the adjusting device (184) to change the preferred direction (146) of the focal zone (106), and/or that the polarization beam splitting element (172) can be rotated by means of the adjusting device (184) to change the preferred direction (146) of the asymmetrical cross section (140) of the focal zone (106).

8. Device according to one of the preceding claims, characterized in that the beam shaping device (110, 110') has a beam diaphragm (170) for forming the asymmetrical cross section (140) of the focal zone (106), by means of which an angular range of a beam shaping device ( 110, 110') formed far-field Intensity distribution (164) is blocked, with an unblocked portion of the far-field intensity distribution (164) to form the elongated focal zone (106) with an asymmetric cross-section (140) is focused.

9. The device according to claim 8, characterized in that the beam diaphragm (170) can be influenced by means of the adjusting device (184) to change the preferred direction (146) of the asymmetrical cross section (140) of the focal zone (106), in particular a means of the beam diaphragm ( 170) the blocked and/or non-blocked angular range of the far-field intensity distribution (164) can be changed by means of the adjusting device (184).

10. Device according to one of the preceding claims, characterized in that a far-field intensity distribution (164) is formed by means of the beam-shaping device (110; 110'), the focal zone (106) being formed by focusing the far-field intensity distribution (164) and wherein the far field intensity distribution (164) focused to form the focal zone (106) can be influenced by means of the adjusting device (184) in order to change the preferred direction (146) of the asymmetrical cross section (140) of the focal zone (106).

11. Device according to one of the preceding claims, characterized by a detection device (192; 192') for the optical detection of an actual preferred direction (194) of the asymmetrical cross section (140) of the focus zone (106) formed, wherein the detection device (192; 192') in particular is connected or can be connected to the control device (186) in a signal-effective manner.

12. The device according to claim 11, characterized in that the detection device (192, 192 ') for the optical detection of the cross section (140) of the formed focal zone (106) is set up, and / or that the detection device (192; 192') for the optical Detection of a respective cross-section (152) of the material (102) of the workpiece (104) with the focal zone (106) generated in the material (102). Material modifications (150) is set up.

13. A method for laser processing a workpiece (104) by means of a focus zone (106), wherein the workpiece (104) has a transparent material in which

- the focal zone (106) is formed from an input laser beam (112) by means of a beam-shaping device (110; 110'), the focal zone (106) being elongate with respect to a longitudinal axis (108) and the focal zone (106) perpendicular to the longitudinal axis ( 108) has an asymmetrical cross section (140) with a preferred direction (146),

- the preferred direction (146) is changed or can be changed during the laser processing of the workpiece (104) by means of an adjusting device (184), and

- the preferred direction (146) is controlled and/or regulated during the laser processing of the workpiece (104) by means of a control device (186), the control device (186) activating the actuating device (184) on the basis of a predetermined assignment rule.

14. The method according to claim 13, characterized in that the preferred direction (146) is aligned at least approximately parallel to a feed direction (148) by means of the control device (186) during the laser processing of the workpiece (104), in which the focal zone (106) Laser processing of the workpiece (104) is moved relative to the workpiece (104).

15. The method according to claim 13 or 14, characterized in that to define the assignment rule, an actual preferred direction (194) of the asymmetrical cross section (140) of the focal zone (106) formed is detected as a function of a control signal, with which the control device (186) controls the setting device (184) for controlling the preferred direction (146).

16. The method according to claim 15, characterized in that to determine the actual preferred direction (194), the cross section (140) of the focus zone (106) formed is optically detected and the preferred direction (146) of the optically detected cross section (140) is determined, and /or that, in order to determine the actual preferred direction (194), a preferred direction (154) of a respective cross section (152) of one or more material modifications (150) is determined, which is determined by subjecting the material (102) of the workpiece (104) to the focal zone ( 140) were generated in the material (102).

17. The method according to claim 16, characterized in that the actual preferred direction (154) of the cross section (152) of a specific material modification (150) is determined by optically detecting cracks (156) which are associated with this material modification (150).