Method and apparatus for laser processing a workpiece

Abstract

The invention relates to a method for laser processing a workpiece (104) having a material (102) which is transparent for the laser processing, in which method an input laser beam (108) is divided into a plurality of sub-beams (116) by means of a beam splitting element (106), wherein the division of the input laser beam (108) by means of the beam splitting element (106) is effected by imposing a phase on a beam cross section (112) of the input laser beam (108), the sub-beams (116) which are coupled out of the beam splitting element (106) are focused by means of focusing optics (118), a plurality of focal elements (120) is configured by focusing the sub-beams (116), and in the method at least one subset of the configured focal elements (120) is loaded onto the material (102) of the workpiece (104) for the laser processing. The phase imposition is effected by means of the beam splitting element (106) in such a way that at least two of the configured focal elements (120) have different intensities (I).

Description

TECHNICAL FIELD

[0001] The invention relates to a method for laser processing a workpiece having a material which is transparent to the laser processing, in which method an input laser beam is divided into a plurality of sub-beams by means of a beam splitting element, wherein the division of the input laser beam by means of the beam splitting element is effected by a phase imprinting of a beam cross section of the input laser beam, the sub-beams coupled out of the beam splitting element are focused by means of focusing optics, a plurality of focal elements are configured by focusing the sub-beams, and in which method at least one subset of the configured focal elements is loaded to the material of the workpiece for the laser processing.

[0002] Furthermore, the invention relates to an apparatus for laser processing a workpiece having a material which is transparent to the laser processing, comprising a beam splitting element for dividing an input laser beam coupled into the beam splitting element into a plurality of sub-beams, wherein the division of the input laser beam by means of the beam splitting element is effected by a phase imprinting of a beam cross section of the input laser beam, and focusing optics for focusing the sub-beams coupled out of the beam splitting element, wherein a plurality of focal elements are configured by focusing the sub-beams for laser processing the workpiece. BACKGROUND

[0003] From DE 10 2014 116 958 A1 a diffractive optical beam shaping element for applying phase curves to a laser beam which is provided for laser processing a material which is largely transparent to the laser beam is known, which diffractive optical beam shaping element has a phase mask which is configured for applying a plurality of beam shaping phase curves to a laser beam which is irradiated onto the phase mask, wherein at least one phase curve of the plurality of beam shaping phase curves is assigned a virtual optical image which can be imaged into an elongated focal region for configuring a modification in the material to be processed.

[0004] From JP 2020 004 889 A an apparatus and a method for cutting and in particular for cutting a substrate are known, wherein a plurality of focal points is generated by means of a spatial light modulator. SUMMARY

[0005] The task on which the invention is based is to provide a method as initially mentioned and an apparatus as initially mentioned by means of which the configuration of material modifications in the material of a workpiece can be better controlled and / or reproduced, so that in particular an improved material separation can be achieved.

[0006] In the method mentioned at the beginning, according to the present invention, the task is solved by applying phase using a beam-splitting element such that at least two of the constructed focal elements have different intensities.

[0007] It has been proven that the strength required to construct a material modification section near the surface (i.e., near the outer and / or upper side of the workpiece) is less than the strength required to construct a material modification section deep within the volume of the material (i.e., far from the closest outer and / or upper side of the workpiece). By constructing multiple focal elements with different strengths, material modification sections with the same type of properties can be constructed within the material of the workpiece, regardless of their depth location within the volume of the material. This, in particular, improves the homogeneity of the material modification section in the thickness and / or depth directions of the material. Consequently, material separation with improved quality and / or homogeneity can be achieved, in particular.

[0008] In particular, at least two of the constructed focal elements have different intensities, and the focal elements are applied to the material of the workpiece for laser processing.

[0009] In particular, the constructed focal elements are arranged in different spatial locations.

[0010] The different intensities of the focal element should be understood in particular as focal elements arranged in different spatial locations having different intensities.

[0011] In particular, the intensity of a defined focal element should be understood as the spatially averaged intensity or maximum intensity of that focal element.

[0012] In particular, the definition of the corresponding intensity of the focal element within a given medium is made while neglecting the absorption effect of that medium. For example, the intensity is defined for use in air and / or in glass.

[0013] In particular, the intensity of the constructed focal element is at least approximately constant over time during laser processing of the workpiece.

[0014] In particular, the focal elements that are different from each other are spaced apart and / or arranged in different spatial locations. In principle, it is possible for the focal elements that are different from each other to partially overlap in space.

[0015] The spatial position of a given focal element should be understood in particular as the position of the center point of the corresponding focal element.

[0016] Advantageously, the strength of the focal element is chosen such that by loading the focal element onto the material, the same type of material modification is generated in the material, and in particular, the same type of material modification is generated in the material regardless of the distance between the corresponding focal element and the outermost part of the workpiece closest to the corresponding focal element. This results in optimized separability of the material along the constructed material modification. Thus, separation can be achieved, for example, in a manner with increased homogeneity and / or with smoother separation edges.

[0017] The same type of material modification section should be understood in particular as a material modification section that has at least approximately the same selective etchability and / or the same spatial extension.

[0018] In particular, modified materials of the same type exhibit the same or similar etching properties. Therefore, optimized separation of materials can be achieved especially by etching with a wet chemical solution.

[0019] Advantageously, the intensity of the focal elements can be selected based on the spacing and / or the spacing region, with the corresponding focal elements spaced apart from the outer side of the workpiece, and especially from the outer side of the workpiece closest to the corresponding focal element, by said spacing and / or said spacing region. Thus, at least approximately the same type of material modification section can be constructed in the material regardless of its spacing and / or spacing region.

[0020] The spacing area should be understood in particular as the spacing within a defined range relative to the outer side of the workpiece, and especially to the outermost side of the workpiece.

[0021] In particular, each defined focal element is explicitly and uniquely assigned to a defined spacing region. Furthermore, different spacing regions do not overlap.

[0022] The spacing direction of the spacing or spacing region is particularly parallel to the thickness direction of the workpiece.

[0023] The workpiece is constructed, for example, in a plate-like or block-like shape.

[0024] Advantageously, as the distance between the corresponding focal element and the outermost point of the workpiece increases, the strength of the focal element is selected to be increasingly greater. Thus, the material modification section located deeper within the volume of the workpiece can be constructed in at least approximately the same manner as the material modification section with a shallower depth.

[0025] For the same reason, it is advantageous that as the center distance between the corresponding spacing region and the outermost point of the workpiece increases, the average strength of the corresponding focal element belonging to the defined spacing region is selected to be increasingly larger.

[0026] In particular, the relative intensity of the constructed focal element can be set to vary by a factor of at least 1.5 and / or at most 5.0, preferably at least 2.0 and / or at most 3.0, and especially preferably 2.5.

[0027] If the relative intensity of the constructed focal elements varies by a factor of 2.0, for example, this means that the constructed focal elements include at least one focal element with minimum intensity and at least one focal element with maximum intensity, wherein the intensity of the focal element with maximum intensity is greater than the intensity of the focal element with minimum intensity by a factor of 2.0.

[0028] Specifically, it can be configured with at least one spacing region, wherein the intensity of the corresponding focal element located within the at least one spacing region is at least approximately constant. For example, multiple spacing regions are provided, and the focal elements belonging to the spacing regions have different intensities. For example, the intensity of the focal elements varies in a stepwise manner.

[0029] Specifically, the configuration may include at least one spacing region, wherein the intensity of a corresponding focal element within this spacing region varies, particularly as the distance between the focal element and the outermost point of the workpiece increases. Specifically, the corresponding intensities of two or more, or all, of the focal elements within this spacing region may be different. For example, the intensities of adjacent focal elements may be different.

[0030] For example, a first spacing region and a second spacing region are provided, wherein the intensity of a corresponding focal element located within the first spacing region varies, and the intensity of a corresponding focal element located within the second spacing region is at least approximately constant. The first spacing region is then, for example, adjacent to or surrounding the outer side of the workpiece. The second spacing region is then, for example, entirely within the material of the workpiece and particularly adjacent to the first spacing region.

[0031] For example, the intensity of the focal element in another spacing region is greater than the intensity of the focal element in the first spacing region by a factor of at least 1.5 to 5.0, preferably 2.0 to 3.0, and particularly preferably 2.5.

[0032] Advantageously, different focal elements can be arranged along a pre-defined machining line, and in particular, these different focal elements are spaced apart and / or have such strength along the machining line that by loading these focal elements onto the workpiece material, material-modified portions are constructed in the material, which can achieve material separation along the machining line. Thus, during laser machining of the material, a structure is created where material-modified portions are formed along the machining line or along a machining surface corresponding to the machining line. In particular, the material can be separated along the machining line or the machining surface.

[0033] For example, at least one processing line has a total length between 50µm and 5000µm.

[0034] In particular, it can be configured such that the material of the workpiece can be separated by applying thermal loading and / or mechanical stress and / or by etching with the aid of at least one wet chemical solution. For example, the etching is performed in an ultrasonically assisted etching bath.

[0035] In particular, the processing line can be configured to be constructed continuously in the space within the thickness of the workpiece material.

[0036] The processing line is not necessarily constructed in a spatially connected manner, but can have different spatially separated sections. In particular, the processing line can have gaps and / or interruptions in which no focal elements are arranged.

[0037] In particular, a processing line is or includes a connecting line between adjacent focal elements.

[0038] Specifically, the angle of attack between the processing line and the outer side of the workpiece can be set to at least 1° and / or a maximum of 9°, through which the focal element is coupled into the workpiece material for laser processing. This allows, for example, vertical cutting to be performed on the workpiece or chamfering of the workpiece at a defined angle.

[0039] In particular, it can be configured such that the angle of attack of the processing line is constant at least in sections, and / or the processing line has multiple sections with different angles of attack.

[0040] Specifically, it can be set that the processing line is at least partially straight, and / or at least partially curved.

[0041] By implementing the machining line as a curve, such as a rounded section, it can be separated from the workpiece. This, for example, allows the creation of rounded edges.

[0042] When implementing a machining line as a curve, the machining line is assigned, for example, a defined angle of attack region, which the machining line has relative to the outer side of the workpiece.

[0043] Advantageously, one or more of the constructed focal elements are arranged at least partially and / or at least temporarily outside the material of the workpiece during laser processing. In particular, this enables the application of focal elements to the workpiece material in the outer region during laser processing, even in the event of thickness fluctuations and / or focal position fluctuations.

[0044] In particular, the processing line extends beyond at least one outer side of the workpiece in the thickness direction during laser processing and / or at least temporarily extends beyond the outer side of the workpiece.

[0045] For example, focal elements arranged outside the material of the workpiece are spaced apart from the outermost part of the workpiece that is closest to these focal elements.

[0046] For example, the section of the processing line outside the material is the tangential continuation of the processing line at the endpoints and / or end sections of the processing line within the material.

[0047] In particular, it can be configured such that, for laser processing of workpieces, the focal element moves relative to the workpiece material at a feed rate.

[0048] In particular, the machining line, together with the focal element, moves relative to the workpiece at a feed rate oriented in the feed direction for laser machining of the workpiece. Therefore, a machining surface corresponding to the machining line is specifically constructed, and the material modification section is arranged along this machining surface.

[0049] Preferably, the focal elements are located at least partially in a plane that is oriented particularly perpendicular to the feed direction. In particular, all the constructed focal elements are located in this plane.

[0050] Advantageously, polarization beam splitting can be performed using a polarization beam splitter, allowing the sub-beams to have at least one of two different polarization states. This is achieved by focusing the sub-beams using focusing optics to construct focal elements with different polarization states, particularly arranged adjacent to each other. This effectively prevents interference between adjacent focal elements. Furthermore, adjacent focal elements can be arranged with a very small spacing between them.

[0051] Material modification portions introduced into transparent materials via ultrashort laser pulses are categorized into three distinct types, see K. Itoh et al., “Ultrafast Processes for Bulk Modification of Transparent Materials”, MRS Bulletin, vol. 31 p. 620 (2006): Type I is isotropic refractive index change; Type II is birefringent refractive index change; and Type III is so-called voids or cavities. Here, the resulting material modification portion is related to the laser beam parameters (e.g., pulse duration, wavelength, pulse energy, and repetition frequency) and material properties (e.g., especially electronic structure and coefficient of thermal expansion), as well as the numerical aperture (NA) of the focused region formed by the laser beam.

[0052] The isotropic refractive index variation of Type I is attributed to localized confined melting caused by the laser pulse and rapid resolidification of the transparent material. For example, in the case of quartz glass, the material has a higher density and refractive index when the quartz glass is rapidly cooled from a higher temperature. That is, if the material melts in the focal volume and is subsequently rapidly cooled, the quartz glass has a higher refractive index in the modified region than in the unmodified region.

[0053] The refractive index change in Type II birefringence can be generated, for example, through interference between an ultrashort laser pulse and the electric field of the plasma generated by the laser pulse. This interference results in periodic modulation of the electron plasma density, which, upon solidification, leads to the birefringence properties of the transparent material, i.e., a direction-dependent refractive index. Type II modification is also accompanied, for example, by the formation of so-called nanogratings.

[0054] For example, high laser pulse energy can be used to generate voids (cavities) in Type III modified sections. Here, void formation is attributed to the explosive extension of highly excited, evaporated material from the focal volume into the surrounding material. This process is also known as micro-explosion. Because this extension occurs within the mass mass of the material, micro-explosions result in a less dense or hollow core (void) or microscopic defects in the submicron or atomic range, which are surrounded by a compressed encapsulated material. Considering the compression at the impact front of the micro-explosion, stresses are generated in transparent materials that may lead to spontaneous crack formation or may promote crack formation.

[0055] In particular, the formation of voids can also accompany Type I and Type II modifications. For example, Type I and Type II modifications can occur in smaller stress regions around the introduced laser pulse. Therefore, when it comes to introducing Type III modifications, there are in any case less dense or hollow cores or defects. For example, in sapphire, in the case of Type III modifications, micro-explosions do not produce cavities, but rather regions of lower density. Furthermore, due to the material stress present in the case of Type III modifications, such modifications are often accompanied by or promote crack formation. When introducing Type III modifications, the formation of Type I and Type II modifications cannot be completely suppressed or avoided. Therefore, it is unlikely to find “pure” Type III modifications.

[0056] With high repetition rates of laser beams, materials cannot be completely cooled between pulses, potentially leading to a cumulative effect of heat introduced from pulse to pulse that can influence material modification. For example, the repetition frequency of the laser beam can be higher than the reciprocal of the material's thermal diffusion time, causing heat accumulation at the focal element due to the gradual absorption of laser energy until the material's melting temperature is reached. Furthermore, due to heat transfer to the region surrounding the focal element, areas larger than the focal element can be melted. The rapid cooling of the heated material after the introduction of an ultrashort laser pulse causes the density and other structural properties of the material at high temperatures to be frozen to some extent.

[0057] In particular, it is possible to construct a material modification section in the material by loading a focal element onto the material of the workpiece, the material modification section being associated with crack formation in the material, and / or to construct a type III material modification section in the material by loading a focal element onto the material of the workpiece.

[0058] The construction of the material modification section is associated with crack formation, and it should be understood in particular that the construction of the material modification section is accompanied by crack formation in the material and / or crack formation occurs in the material when the material modification section is constructed.

[0059] In particular, it is possible to construct a material modification section in the material by loading a focal element onto the material of the workpiece, the material modification section being associated with a change in the refractive index of the material, and / or to construct a type I material modification section and / or a type II material modification section in the material by loading a focal element onto the material of the workpiece.

[0060] The construction of the material modification section is related to the change in refractive index. In particular, it should be understood that the construction of the material modification section is accompanied by a change in the refractive index in the material and / or a change in the refractive index in the material occurs when the material modification section is constructed.

[0061] In the aforementioned apparatus for laser processing of workpieces, according to the present invention, phase is applied by means of a beam-splitting element such that at least two of the constructed focal elements have different intensities.

[0062] The device according to the invention particularly possesses one or more features and / or advantages of the method according to the invention. Advantageous embodiments of the device according to the invention have been described in the context of the method according to the invention.

[0063] In particular, the device includes at least one polarization beam splitter element, which is arranged in front of or behind the beam splitter element relative to the beam propagation direction of the input laser beam. Polarization beam splitting is performed by means of the polarization beam splitter element, such that the sub-beams incident on the focusing optics each have one of at least two different polarization states, and the focusing optics are used to focus the sub-beams to construct focal elements with different polarization states.

[0064] In particular, the method according to the invention can be implemented using the device according to the invention, or the method according to the invention can be implemented using the device according to the invention.

[0065] In particular, the focal element is formed by the input laser beam, wherein the focal element is formed, in particular, by deformation and / or beamforming of the input laser beam.

[0066] Specifically, the input laser beam can be divided using a beam-splitting element by phase manipulation of the input laser beam's phase. In particular, the division of the input laser beam using a beam-splitting element is performed solely by phase manipulation of the input laser beam's phase.

[0067] Focusing optics are not necessarily constructed as separate optical elements. In principle, it is also possible for focusing optics to be integrated into other components of the device, such as into beam-splitting elements and / or into polarization beam-splitting elements.

[0068] In particular, the phase application of the beam cross-section of the first input beam performed by means of the beam splitter can be set and / or defined in a variable manner.

[0069] The beam splitter is particularly configured as a diffraction beam splitter and / or as a 3D beam splitter.

[0070] In particular, the device according to the invention includes a laser source for providing an input laser beam, which is in particular a pulsed laser beam and / or an ultrashort pulse laser beam.

[0071] In particular, the workpiece is made of a material that is transparent to the input laser beam and / or of a material that is transparent to the laser beam from which the focal element is formed.

[0072] Transparent materials should be understood in particular as materials through which at least 70% and especially at least 80% and especially at least 90% of the laser energy of a laser beam is transmitted, and the focal element is formed by the laser beam.

[0073] In particular, the focal element is constructed by or provided by an ultrashort pulse laser beam. This ultrashort pulse laser beam specifically includes ultrashort laser pulses.

[0074] For example, the input laser beam and / or the following laser beams have wavelengths of at least 300 nm and / or a maximum of 1500 nm: the focal element is formed by such laser beams. For example, the wavelength is 515 nm or 1030 nm.

[0075] In particular, the input laser beam and / or the following laser beams have an average power of at least 1W to 1kW: the focal element is formed by these laser beams. For example, the laser beam comprises pulses with pulse energies of at least 10μJ and / or at most 50mJ. The laser beam can be configured to comprise a single pulse or a short pulse train, wherein the short pulse train has 2 to 20 sub-pulses and, in particular, a time interval of approximately 20ns.

[0076] In particular, a focal element should be understood as a radiating region with a defined spatial extension. To determine the spatial dimension of a focal element, such as its diameter, only intensity values ​​greater than a defined intensity threshold are considered. Here, the intensity threshold is chosen, for example, such that values ​​less than the threshold have such low intensities that they are no longer critically relevant to the material-material interaction used to construct the material-modifying portion. For example, the intensity threshold is 50% of the maximum global intensity of the focal element.

[0077] In particular, the statement "at least approximate" or "approximate" should generally be understood as a deviation of up to 10%. Unless otherwise stated, the statement "at least approximate" or "approximate" should especially be understood as the actual value and / or spacing and / or angle deviating from the ideal value and / or spacing and / or angle by a maximum of 10%. Attached Figure Description

[0078] The following description of preferred embodiments is intended to illustrate the invention in more detail in conjunction with the accompanying drawings.

[0079] The attached diagram shows:

[0080] Figure 1A schematic diagram showing an embodiment of an apparatus for laser processing of workpieces;

[0081] Figure 2 A schematic cross-sectional view of a section of the workpiece is shown, with multiple focal elements loaded onto the workpiece for laser processing;

[0082] Figure 3 A cross-sectional schematic diagram of a section of a workpiece loaded with multiple focal elements is shown, wherein multiple focal elements are located outside the workpiece;

[0083] Figure 4 A schematic cross-sectional view of a section of the workpiece is shown, in which a material modification section is generated by loading a focal element onto the workpiece, the material modification section being accompanied by the formation of material cracks;

[0084] Figure 5a A schematic cross-sectional view showing the simulated intensity distribution of a focal element used for laser processing of a workpiece;

[0085] Figure 5b Showing the allocation according to Figure 5a The phase distribution of the intensity distribution;

[0086] Figure 6a A perspective view of a workpiece is shown, the workpiece having a material-modified portion constructed thereon, the material-modified portion extending along machining lines and / or machining surfaces; and

[0087] Figure 6b A schematic diagram of two workpiece segments is shown, the workpiece segments being separated by machining lines and / or machining surfaces according to... Figure 6a The workpiece is formed. Detailed Implementation

[0088] Identical or functionally equivalent elements are given the same reference numerals in all the figures.

[0089] An embodiment of a device for laser-processing workpieces Figure 1 It is shown in the diagram and indicated therein by 100. With the aid of device 100, localized material modification portions, such as defects in the submicron or atomic range, can be generated in the material 102 of workpiece 104, which result in material weakening. Workpiece 104 can be separated at these material modification portions, or a workpiece segment can be separated from workpiece 104, for example.

[0090] In particular, the material modification section can be introduced into the material 102 at an angle of attack using the equipment 100, so that the edge area of ​​the workpiece 104 can be chamfered or beveled by separating the corresponding workpiece section from the workpiece 104.

[0091] The device 100 includes a beam splitter element 106 into which an input laser beam 108 is coupled. The input laser beam 108 is provided, for example, by means of a laser source 110. For example, the input laser beam 108 is a pulsed laser beam and / or an ultrashort pulse laser beam.

[0092] The input laser beam 108 should be understood in particular as a beam focusing beam, which includes a plurality of beams that extend particularly in parallel. The input laser beam 108 particularly has a transverse beam cross section 112 and / or a transverse beam extension, by means of which the input laser beam 108 is incident on the beam splitting element 106.

[0093] The input laser beam 108 incident on the beam splitter 106 has, in particular, a wavefront 114 that is at least approximately planar.

[0094] The input laser beam 108 is divided into multiple sub-beams 116 and / or the sub-beams are focused using a beam-splitting element 106. Figure 1 In the example shown, two sub-beams, 116a and 116b, are labeled as different from each other.

[0095] The sub-beams 116 coupled from the beam splitter 106 have a particularly divergent beam profile.

[0096] In order to focus the sub-beam 116 coupled from the beam splitter 106, the device 100 includes a focusing optics 118 into which the sub-beam 116 is coupled. The focusing optics 116 is configured, for example, as a microscope objective and / or lens element.

[0097] In particular, the different sub-beams 116 are incident on the focusing optics 118 with location offset and / or angular offset.

[0098] The sub-beam 116 is focused by a focusing optics device 118, thereby constructing a plurality of focal elements 120, which are arranged at different spatial locations. In principle, it is possible for adjacent focal elements 120 to partially overlap in space.

[0099] For example, the corresponding focal element 120 is respectively associated with one or more sub-beams 116 and / or sub-beam focusing. For example, the corresponding focal element 120 constructs one or more sub-beams 116 and / or sub-beam focusing by focusing.

[0100] In order to laser process workpiece 104, a focal element 120 is introduced into the material 102 of workpiece 104 and the focal element is moved relative to the material 102.

[0101] The input laser beam 108 coupled into the beam splitter element 106 is associated with a defined focal distribution. This focal distribution describes the geometry and / or intensity profile of the focal element, which is constructed by focusing the input laser beam 108 before coupling it into the beam splitter element 106. In particular, the geometry should be understood as the spatial shape and / or spatial extension of the constructed focal element.

[0102] For example, when an input laser beam is provided, for instance, by means of a laser source 110, the input laser beam 108 has a Gaussian beam profile. In this case, a focal element is constructed by focusing the input laser beam 108 to have a focal distribution having a Gaussian shape and / or a Gaussian intensity profile.

[0103] Alternatively, the input laser beam 108 may be configured, for example, with a Bezier-shaped beam profile, such that by focusing the input laser beam 108, a focal element is constructed having a focal distribution having a Bezier-shaped shape and / or a Bezier-shaped intensity curve.

[0104] By dividing the input laser beam 108 with the sub-beams 116 and / or sub-beam focusing by the beam splitting element 106, the focal distribution of the input laser beam 108 is associated with such a focal distribution, such that by focusing the sub-beams 116, a focal element 120 having such a focal distribution and / or having a focal distribution based on such a focal distribution is constructed.

[0105] exist Figure 1 In the example shown, the input laser beam 108 has a Gaussian beam profile, meaning that the input laser beam 108 is associated with a focal distribution having a Gaussian shape and / or a Gaussian intensity curve. For example, focal elements 120 have focal distributions 121 that have the Gaussian shape and / or the Gaussian intensity curve, or have a shape and / or intensity curve based on the Gaussian shape and / or the Gaussian intensity curve.

[0106] The focal distribution 121 is a characteristic of the corresponding focal element 120 and describes the shape and / or intensity curve of the corresponding focal element.

[0107] If the input laser beam 108 is, for example, associated with a Bezier-shaped beam profile, then the focal elements 120 configured for laser processing the workpiece 104 each have a focal distribution 121 having either the Bezier-shaped beam profile or a beam profile based on the Bezier-shaped beam profile. Thus, the focal elements 120 can be configured, for example, to have a focal distribution with an elongated shape and / or an elongated intensity curve.

[0108] The device 100 can be configured to have a beamforming device 122 for beamforming the input laser beam 108 (in... Figure 1 (Illustrated). For example, the beamforming device 122 is arranged in front of the beam splitting element 106 and / or between the laser source 110 and the beam splitting element 106 with respect to the beam propagation direction 124 of the input laser beam 108.

[0109] With the help of the beamforming device 122, the input laser beam 108 can be fitted with a defined focal distribution and / or a defined beam profile.

[0110] The beamforming device 122 can be configured, for example, to construct a laser beam with a quasi-diffractive and / or Bezier-shaped beam profile from a laser beam having a Gaussian beam profile. Then, correspondingly, the input laser beam 108 coupled into the beam splitting element 106 has a quasi-diffractive and / or Bezier-shaped beam profile.

[0111] For the construction and properties of quasi-non-diffractive and / or Bessel-shaped beams with curved shapes, refer to the scientific publication “Bessel-like optical beams with arbitrary trajectories” by I. Chremmos et al., Optics Letters, Vol. 37, No. 23, December 1, 2012.

[0112] The beam splitting is performed using the beam splitter element 106, in particular, the focal elements 120 are each constructed as copies. In particular, one or more of the constructed focal elements have the same geometry and / or the same intensity profile.

[0113] In particular, the beam splitter 106 allows for the setting of corresponding spacing d and / or location offset between adjacent focal elements 120. Preferably, the spacing d, which can be set by the beam splitter 106, lies in a plane that is transverse to and, in particular, perpendicular to the feed direction 126 in which the focal elements 120 move relative to the workpiece 104 for laser processing. For example, the spacing d can be set in components in two spatial directions by the beam splitter 106, the two spatial directions being transverse to or located in the aforementioned plane (in... Figure 1 The example shown represents the x and z directions.

[0114] exist Figure 1 In the example shown, the feed direction 126 is oriented parallel to the y-direction, which is perpendicular to the x and z directions.

[0115] In particular, in order to set the spacing d, the sub-beam 116 is constructed such that the sub-beam is incident on the focusing optics 118 in a manner having a defined location offset and / or a defined convergence and / or divergence. The sub-beam 116 is then focused by means of the focusing optics 118, thereby constructing a focal element 120 having a corresponding spacing d and / or location offset.

[0116] Furthermore, a defined intensity I can be assigned to each of the constructed focal elements 120 by means of the beam splitter 106. In particular, the corresponding intensity I of the focal element 120 is set by means of the beam splitter 106, and especially by applying the set intensity I to the phase of the input laser beam. Then, by focusing the sub-beams 116 coupled out from the beam splitter 106, a focal element 120 with a defined intensity I is constructed.

[0117] In particular, the intensity I of the defined focal element 120 should be understood as the absolute intensity and / or average intensity of the corresponding focal element 120.

[0118] The beam is split by means of the beam splitting element 106 such that two or more focal elements in the constructed focal element 120 have different intensities I.

[0119] To perform beam splitting using beam splitter element 106, a defined transverse phase distribution is applied to the transverse beam cross-section 112 of the input laser beam 108. The transverse beam cross-section or transverse phase distribution should be understood in particular as the beam cross-section or phase distribution in a plane oriented transversely to and especially perpendicular to the beam propagation direction 124. Figure 1 An example of the lateral phase distribution for the beam coupled from the beam splitter element 106 is shown.

[0120] The focal element 120 is constructed by the interference of the focused sub-beam 116, wherein, for example, constructive interference, destructive interference, or an intermediate state between the two may occur, such as partially constructive interference or partially destructive interference.

[0121] In order to construct focal elements 120 with corresponding spacing d and / or location offset, phase is applied by means of beam splitting element 106 in such a way that the phase distribution associated with each focal element 120 has defined optical grating components and / or optical lens components.

[0122] After the sub-beam 116 is focused, the constructed focal element 120 experiences a corresponding location shift in the first spatial direction, for example, the x-direction, due to the optical grating component. Due to the optical lens component, the sub-beam 116 or the sub-beam convergence is incident on the focusing optics 118 at different angles or with different convergence or divergence, which, after focusing, results in a location shift in the second spatial direction, for example, the z-direction.

[0123] The intensity of the corresponding focal element 120 is determined by the phase position of the focused sub-beams 116 relative to each other. These phase positions can be defined by the aforementioned optical grating components and optical lens components. When designing the beam splitter 106, the phase positions of the focused sub-beams 116 can be selected relative to each other such that the focal elements 120 each have the desired intensity.

[0124] Regarding the technical implementation and characteristics of the beam splitter element 106, refer to the scientific publication "Structured light for ultrafast laser micro- and nanoprocessing" by D. Flamm et al., arXiv:2012.10119v1 [physics.optics], December 18, 2020. The entire contents of that publication are explicitly cited.

[0125] For example, beam splitter 106 is configured as a 3D beam splitter.

[0126] The device 100 may be configured to have a polarization beam splitter element 128. With the aid of the polarization beam splitter element 128, the input laser beam 108 and / or the sub-beams coupled from the beam splitter element 106 are polarized and split into beams having at least one of two different polarization states.

[0127] The polarization beam splitter 128 can be arranged, for example, in front of or behind the beam splitter 106, relative to the beam propagation direction 124 of the input laser beam 108.

[0128] In particular, the polarization state mentioned should be understood as a linear polarization state, where, for example, two different polarization states and / or polarization states oriented perpendicular to each other are provided.

[0129] In particular, the beam coupled from the polarizing beam splitter 128 is polarized in such a way that the electric field is oriented (transversely) in a plane perpendicular to the direction of beam propagation.

[0130] For polarization beam splitting, polarization beam splitting element 128 has, for example, a birefringent lens element and / or a birefringent wedge element. The birefringent lens element and / or birefringent wedge element are, for example, made of or comprise quartz crystal.

[0131] Regarding the operating principle and implementation scheme of the polarization beam splitter 128, reference is made to German patent applications with the same applicant, file number 102020 207 715.0 (filed June 22, 2020) and file number 10 2019 217 577.5 (filed November 14, 2019). The entire contents of the aforementioned German patent applications are expressly incorporated herein by reference.

[0132] By polarization beam splitting using the polarization beam splitter 128, the sub-beams incident on the focusing optics 118 each have, for example, one of at least two different polarization states. Therefore, by focusing these sub-beams 116 using the focusing optics 118, focal elements 120 can be constructed from beams having defined polarization states. Thus, each focal element 120 can be assigned a defined polarization state.

[0133] In particular, it is possible to set that adjacent focal elements 120 have different polarization states.

[0134] In particular, the beam splitter 106 and / or the polarization beam splitter 128 are respectively configured as far-field beamforming elements.

[0135] For laser processing of workpiece 104, at least a subset and / or selection of the constructed focal elements 120 are introduced into material 102. Figure 5b ).

[0136] Each of the constructed focal elements 120 is assigned a defined local position x0, z0, at which a corresponding focal element 120 is arranged relative to the material 102 of the workpiece 104. Furthermore, each of the focal elements 120 is assigned a defined intensity I.

[0137] In particular, the local positions of the corresponding focal elements 120 are located in a plane perpendicular to the feed direction 126. In particular, all the constructed focal elements 120 are located at least partially in a plane oriented perpendicular to the feed direction 126.

[0138] By using the beam splitter 106, not only can the local position of the corresponding focal element 120 be defined, but also the intensity I of the corresponding focal element 120 can be defined. To this end, the phase distribution applied to the beam cross section 112 of the input laser beam 108 by means of the beam splitter 106 is adjusted accordingly.

[0139] The coupling of the focal element 120 introduced into the material 102 for laser processing of the workpiece 104 is, for example, carried out through the first outer side 130 of the workpiece 104.

[0140] For example, workpiece 104 is plate-shaped and / or block-shaped. The second outer side 132 of workpiece 104 is arranged, for example, spaced apart from the first outer side 130 in the thickness direction 134 and / or depth direction of workpiece 104.

[0141] The feed direction 126 is oriented transversely to and in particular perpendicular to the thickness direction 134 of the workpiece 104.

[0142] In particular, the constructed focal element 120 is arranged along the defined machining line 136. This machining line 136 corresponds to the desired machining geometry, and the laser machining of the workpiece 104 should be performed with this desired machining geometry.

[0143] The corresponding spacing d and strength I of the focal elements 130 arranged along the processing line 136 are chosen such that by loading these focal elements 120 onto the material 102, a material modification section 138 is constructed. Figure 2 The material modification section can achieve material separation along the processing line 136 and / or processing surfaces corresponding to the processing line 136.

[0144] In particular, the machining line 136 may be configured to extend between the first outer side 130 and the second outer side 132, and especially coherently between the first outer side and the second outer side 132 of the workpiece 104.

[0145] It can be configured that the processing line 136 has multiple different sections 140. For example, in Figure 4 In the example shown, the processing line 136 has a first segment 140a, a second segment 140b and a third segment 140c, wherein, relative to the thickness direction 134, the second segment 140b is adjacent to the first segment 140a and the third segment 140c is adjacent to the second segment 140b.

[0146] However, the processing line 136 is not necessarily constructed in a continuous and / or differentiable manner. It may be configured such that the processing line 136 has interruptions and / or gaps, in particular without the focal element 120 arranged on the interruptions and / or gaps.

[0147] Processing line 136 and / or different sections 140 of processing line 136 can be constructed, for example, as straight lines or curves.

[0148] Furthermore, a defined angle of attack α and / or angle of attack region are assigned to the machining line 136 and / or the corresponding segment 140 of the machining line 136, and the machining line 136 or the corresponding segment 140 and the first outer side 130 of the workpiece 104 form the angle of attack and / or the angle of attack region.

[0149] In the illustrated embodiment, the angle of attack α of the first segment 140a and the third segment 140c is 45° in magnitude, and the angle of attack of the second segment is 90°.

[0150] The focal elements 120 belonging to the defined segment 140 can each have different intensities I.

[0151] The setting is configured such that the corresponding intensity I of the determined focal element 120 is selected based on the spacing d0 and / or the spacing region dr, and the corresponding focal element 120 is spaced apart from the outermost of the workpiece 104, 130, 132, of the workpiece 104 closest to the corresponding focal element 120 by the spacing and / or the spacing region dr. The spacing direction of the spacing d0 and / or the spacing region dr is specifically oriented parallel to the thickness direction 134 of the workpiece 104.

[0152] The outermost edge closest to the focal element 120 should be understood as the following outer edges 130, 132 of the workpiece: these outer edges have the shortest distance from the corresponding focal element 120, and especially with respect to the thickness direction 134. Figure 2 In the example shown, the outermost point closest to the focal element 120a is the first outermost point 130, and the outermost point closest to the focal element 120b is the second outermost point 132.

[0153] Assign a center spacing dr to each spacing region dr m Among them, the center spacing dr m It should be understood as the average spacing between the corresponding spacing region dr and the closest outermost parts 130, 132 of workpiece 104 and / or the spacing calculated on an average basis.

[0154] According to Figure 2 In the example, a first spacing region dr1 and a second spacing region dr2 are provided. The focal element 120 located in the first spacing region dr1 has a first intensity I1, and the focal element 120 located in the second spacing region dr2 has a second intensity I2, which is different from the first intensity I1. Here, intensity I2 is greater than intensity I1 (in...). Figure 2 (The winning bid is indicated).

[0155] For example, the first spacing region dr1 and the second spacing region dr2 are continuous and / or non-overlapping spacing regions. Thus, each focal element 120 is specifically and uniquely assigned to a defined spacing region dr.

[0156] exist Figure 2 In the example shown, the corresponding intensities I1 and I2 of the focal elements 120 located in the first spacing region dr1 and the second spacing region dr2 are at least approximately constant. However, it is also possible in principle to provide at least one spacing region dr in which two or more focal elements 120 located therein have intensities I that are different from each other.

[0157] A focal element 120 can be configured such that, during laser processing of the workpiece 104, it is arranged at least segmentally outside the workpiece 104 at a defined time point and / or at a defined location. In this case, the focal element 120 is arranged along a processing line 136 having at least one segment 142 in which the processing line 136 extends beyond a first outer side 130 and / or a second outer side 132 of the workpiece 104.

[0158] According to Figure 2 In the example, the processing line has two sections 142.

[0159] Section 142 is, for example, the tangential continuation of the processing line 136 at the endpoint 144 and / or end section of the processing line 136 within the material 102.

[0160] In particular, the arrangement of processing line 136 in section 142 outside material 102 at the maximum spacing d max The inner extension extends beyond the outermost segment 142 of the workpiece 104, at a distance d. max The spacing direction is oriented in the thickness direction 134.

[0161] In particular, the maximum spacing d max The spacing of the following focal element 120c arranged outside material 102 is: the focal element has the largest spacing with the nearest outermost 130, 132.

[0162] In particular, choosing the maximum spacing d in this way max This allows for compensation of thickness variations and / or axial tolerances in material 102.

[0163] If the thickness of material 102 increases, for example, in a defined region along the feed direction 126, then a focal element 120 is loaded onto material 102 in that region, the focal element being arranged in other regions outside of material 102.

[0164] By loading the focal element 120 and / or introducing the focal element 120 into the material 102, localized material modification parts 146 are constructed respectively, said material modification parts being arranged at the corresponding local positions x0, z0 of the corresponding focal element 120 in the material 102. Figure 3 ).

[0165] By appropriately selecting processing parameters, such as the corresponding spacing d between the focal elements 120, the corresponding intensity I of the focal elements, the feed rate oriented in the feed direction 126, and the laser parameters of the input laser beam 108, the material modification section 146 can be constructed, for example, as a type III modification section, which is accompanied by the spontaneous formation of cracks 148 in the material 102 of the workpiece 104. In particular, cracks 148 are constructed between adjacent material modification sections 146.

[0166] Alternatively, the material modification section 146 may be configured as a type I modification section and / or a type II modification section by appropriately selecting processing parameters, the type I modification section and / or type II modification section being accompanied by heat accumulation in the material 102 and / or accompanied by a change in the refractive index of the material 102.

[0167] The material modification section 146 is configured as a type I modification section and / or a type II modification section, which is associated with heat accumulation in the material 102 of the workpiece 104. In particular, in order to construct these material modification sections 146, the corresponding spacing d between the focal elements 120 is chosen to be so small that this heat accumulation occurs when the focal elements are loaded onto the material 102.

[0168] Figure 4 The simulated intensity distribution of multiple focal elements 120 is shown, wherein the focal elements arranged below in the z-direction have a smaller intensity I than the focal elements 120 arranged above. In the grayscale schematic shown, lighter-colored areas are used for higher intensities.

[0169] Figure 5a The assignment of the beam coupled from the beam splitter 106 is shown according to... Figure 5b The intensity distribution, where the grayscale scale ranges from white (phase + π) to black (phase - π).

[0170] The laser processing of workpiece 104 using equipment 100 is carried out in the following manner:

[0171] In order to perform laser processing, a focal element 120 is loaded onto the material 102 of the workpiece 104, and the focal element 120 moves relative to the workpiece 104 through the material 102 of the workpiece in the feed direction 126.

[0172] Here, material 102 is a material that is transparent with respect to the wavelength of the beams in which focal elements 120 are formed. For example, material 102 is a glass material.

[0173] By loading a focal element 120 into the material 102, a material modification section 146 is constructed in the material 102, which is arranged along the processing line 136. In the example shown in FIG6, the material modification section 146 is constructed continuously within a thickness D of the material 102 oriented in the thickness direction 134.

[0174] By moving the focal element 120 relative to the material 102 along a predetermined trajectory 150, a machining surface 152 corresponding to the machining line 136 is constructed, and a material modification part 146 is arranged on this machining surface. This results in the material modification part 146 being constructed and / or arranged along the plane of the machining surface 152.

[0175] The spacing between adjacent material modification sections 138 in the feed direction 126 can be defined, for example, by setting the pulse duration of the input laser beam 108 and / or by setting the feed speed.

[0176] The material modification portion 146 constructed along the machined surface 152 particularly results in a reduction in the strength of the material 102. Therefore, after the material modification portion 146 is constructed on the machined surface 152, for example by applying mechanical force, the material 102 can be divided into two distinct workpiece segments 154a and 154b. Figure 5a ).

[0177] In the example shown, workpiece segment 154b is a good workpiece segment with a desired edge shape that corresponds to the shape of machining line 136. In this case, workpiece segment 188b is a surplus workpiece segment and / or a scrap segment.

[0178] The material 102 of the workpiece 104 is, for example, quartz glass. For example, to construct the material modification section 146 as a Type I modification section and / or a Type II modification section, a laser beam with a wavelength of 1030 nm and a pulse duration of 1 ps is used to form a focal element 120. Furthermore, the numerical aperture of the focusing optics 118 is 0.4, and the pulse energy of the unique focal element 120 is 50 to 200 nJ.

[0179] In order to construct the material modification section 146 as a type III modification section, with all other parameters being equal, the pulse energy assigned to the unique focal element 120 is 500 to 2000 nJ.

[0180] Figure 6b List of reference signs

[0181] α Angle of attack

[0182] d Spacing

[0183] d0 spacing

[0184] d max Maximum spacing

[0185] dr spacing area

[0186] dr1 spacing area

[0187] dr2 spacing area

[0188] dr m center spacing

[0189] D Thickness

[0190] I Intensity

[0191] I1 strength

[0192] I2 strength

[0193] L (excess length)

[0194] Position of x0 in the x-direction

[0195] The position of z0 in the y direction

[0196] 100 devices

[0197] 102 Materials

[0198] 104 workpieces

[0199] 106 beam splitter elements

[0200] 108 Input laser beam

[0201] 110 laser source

[0202] 112 Beam cross-section

[0203] 114 Wavefront

[0204] 116 beamlets

[0205] 116a beamlet

[0206] 116b sub-beam

[0207] 118 Focusing Optics

[0208] 120 focal elements

[0209] 120a focal element

[0210] 120b focal element

[0211] 120c focal element

[0212] 121 Focal Distribution

[0213] 122 Beamforming device

[0214] 124 Beam propagation direction

[0215] 126 Feed direction

[0216] 128 Polarization beam splitter element

[0217] 130 First outer side

[0218] 132 Second outer side

[0219] 134 Thickness direction

[0220] 136 processing line

[0221] 138 Materials Modification Department

[0222] Section 140

[0223] 140a First Section

[0224] 140b Second Section

[0225] 140c Third Section

[0226] Section 142

[0227] 144 Endpoint / Terminal Section

[0228] 146 Materials Modification Department

[0229] 148 Cracks

[0230] 150 trajectory

[0231] 152 machined surface

[0232] 154a Workpiece Section

[0233] 154b Workpiece section

Claims

1. A method for laser-processing a workpiece (104), the workpiece having a material (102) transparent to the laser processing, wherein an input laser beam (108) is divided into a plurality of sub-beams (116) by means of a beam-splitting element (106), wherein, The division of the input laser beam (108) by means of the beam splitting element (106) is performed by applying a phase to the beam cross section (112) of the input laser beam (108), and the sub-beams (116) coupled from the beam splitting element (106) are focused by means of a focusing optics (118), and a plurality of focal elements (120) are constructed by focusing the sub-beams (116), and in the method, at least a subset of the constructed focal elements (120) is loaded onto the material (102) of the workpiece (104) for the laser processing, characterized in that the phase application is performed by means of the beam splitting element (106) such that at least two of the constructed focal elements (120) have different intensities (I).

2. The method according to claim 1, characterized in that, The intensity (I) of the focal element (120) is selected such that by loading the focal element (120) onto the material (102), the same type of material modification part (138) is generated in the material (102).

3. The method according to claim 1 or 2, characterized in that, The intensity (I) of the focal element (120) is selected according to the spacing and / or the spacing region (dr), and the corresponding focal element (120) is spaced apart from the outer side (130, 132) of the workpiece (104) by the spacing and / or the spacing region.

4. The method according to claim 3, characterized in that, As the distance between the corresponding focal element (120) and the nearest outer side (130, 132) of the workpiece (104) increases, the intensity (I) of the focal element (120) is selected to be larger and larger.

5. The method according to claim 3, characterized in that, With the corresponding spacing region (dr) and the center distance (dr) of the closest outer side (130, 132) of the workpiece m As the ) increases, the average intensity (I) of the corresponding focal element (120) belonging to the defined spacing region (dr) is selected to be larger and larger.

6. The method according to claim 3, characterized in that, At least one spacing region (dr) is provided, wherein the intensity (I) of the corresponding focal element (120) located within the at least one spacing region (dr) is at least approximately constant.

7. The method according to claim 3, characterized in that, At least one spacing region (dr) is provided, wherein the intensity (I) of the corresponding focal element (120) located within the at least one spacing region (dr) is varied.

8. The method according to claim 1 or 2, characterized in that, Different focal elements (120) are arranged along a pre-given processing line (136).

9. The method according to claim 8, characterized in that, The angle of attack (α) between the processing line (136) and the outer side (130, 132) of the workpiece (104) is at least 1° and / or at most 9°, and the focal element (120) is coupled into the material (102) of the workpiece (104) through the outer side for the laser processing.

10. The method according to claim 1 or 2, characterized in that, One or more of the constructed focal elements (120) are arranged at least partially and / or at least temporarily outside the material (102) of the workpiece (104) during laser processing of the workpiece (104).

11. The method according to claim 1 or 2, characterized in that, Polarization beam splitting is performed by means of a polarization beam splitter, such that the sub-beam (116) has one of at least two different polarization states, wherein the focal element (120) with different polarization states is constructed by focusing the sub-beam (116) by means of the focusing optics (118).

12. The method according to claim 1 or 2, characterized in that, By loading the focal element (120) onto the material (102) of the workpiece (104), a material modification section (138) is constructed in the material (102), the material modification section being associated with crack formation in the material (102), and / or by loading the focal element (120) onto the material (102) of the workpiece (104), a type III material modification section (138) is constructed in the material.

13. The method according to claim 1 or 2, characterized in that, By loading the focal element (120) onto the material (102) of the workpiece (104), a material modification section (138) is constructed in the material (102), the material modification section being associated with a change in the refractive index of the material (102), and / or by loading the focal element (120) onto the material (102) of the workpiece (104), a type I material modification section (138) and / or a type II material modification section (138) is constructed in the material.

14. The method according to claim 2, characterized in that, Regardless of the distance between the corresponding focal element (120) and the outermost (130, 132) of the workpiece (104) closest to the corresponding focal element (120), the same type of material modification part (138) is produced in the material (102).

15. The method according to claim 3, characterized in that, The corresponding focal element (120) is spaced apart from the outer side (130, 132) of the workpiece (104) closest to the corresponding focal element (120) by the spacing and / or the spacing region.

16. The method according to claim 7, characterized in that, As the distance between the focal element (120) and the outermost (130, 132) of the workpiece (104) increases, the intensity (I) of the focal element (120) located in the distance region (dr) increases.

17. The method according to claim 8, characterized in that, The distinct focal elements (120) are spaced apart along the machining line (136) and / or have such strength (I) that by loading the focal elements (120) onto the material (102) of the workpiece (104), a material modification section (138) is constructed in the material (102), which enables the separation of the material (102) along the machining line (136).

18. The method according to claim 11, characterized in that, Focal elements (120) with different polarization states are arranged adjacent to each other.

19. An apparatus for laser-processing a workpiece (104) having a material (102) transparent to the laser processing, the apparatus comprising a beam-splitting element (106) and a focusing optics (118), the beam-splitting element being used to divide an input laser beam (108) coupled into the beam-splitting element (106) into a plurality of sub-beams (116), wherein, The division of the input laser beam (108) by means of the beam splitting element (106) is performed by applying a phase to the beam cross section (112) of the input laser beam (108), the focusing optics being used to focus the sub-beams (116) coupled from the beam splitting element (106), wherein a plurality of focal elements (120) are constructed by focusing the sub-beams (116) for laser processing of the workpiece (104), characterized in that the phase is applied by means of the beam splitting element (106) such that at least two of the constructed focal elements (120) have different intensities (I).

20. The device according to claim 19, characterized in that, The division of the input laser beam (108) by means of the beam splitting element (106) is performed by phase manipulation.

21. The device according to claim 20, characterized in that, The division of the input laser beam (108) by means of the beam splitting element (106) is performed only by phase manipulation of the phase of the input laser beam (108).

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