Laser system and method for laser processing a workpiece

Abstract

The invention relates to a laser system for laser machining a workpiece (104) using an interference pattern (124), the laser system comprising: at least one laser beam source (106) for providing a plurality of coherent laser beams (112); an amplification device (118) for forming an amplified coherent laser beam (113) by amplifying the coherent laser beam (112); a phase adjustment device (114) for adjusting a corresponding phase difference between the coherent laser beam (112) and / or the amplified coherent laser beam (113); and a beam convergence region (130) in which an output laser beam (102) based on the amplified coherent laser beam (113) or corresponding to the amplified coherent laser beam (113) converges to form an interference pattern (104), in which at least a beam portion of a different output laser beam (102) converges in the beam convergence region (130).

Description

Technical Field

[0001] The present invention relates to laser systems and methods for laser processing of a workpiece using interference patterns. Background Art

[0002] DE 10 2008 037 042 A1 discloses an apparatus for shaping a laser beam, comprising: a symmetrization device, which can interact with the laser beam to be shaped so that after the interaction, at least two segments or sub-beams of the laser beam that are different in the transverse direction of the laser beam are spatially coherent with each other at least at a certain point or in a certain area; and a superposition device, which is used to superimpose the at least two segments or sub-beams with each other, wherein the superposition device is arranged downstream of the symmetrization device in the beam path of the laser beam.

[0003] DE 10 2018 105 254 B4 discloses a method for processing an object by means of an interfering laser beam, wherein a collimated laser beam is generated, the intensity distribution and / or the phase trend in a cross section of the laser beam is influenced, the laser beam is split into two sub-beams, and the sub-beams are deflected and focused so that the sub-beams overlap in the object material in a processing area, the deflection and focusing of the sub-beams including aberration correction. Summary of the invention

[0004] The invention is based on the object of providing a laser system and a method as described above, which can be used flexibly and variously and which enable a high degree of control over the characteristics of the interference pattern intended for laser processing of a workpiece.

[0005] According to the invention, this object is achieved in the laser system mentioned at the beginning in the following manner, which laser system comprises: at least one laser beam source, which is used to provide a plurality of coherent laser beams; an amplifying device, which is used to form an amplified coherent laser beam by amplifying the coherent laser beams; a phase adjustment device, which is used to adjust the corresponding phase differences between the coherent laser beams; and a beam convergence region, in which output laser beams based on the amplified coherent laser beams or output laser beams corresponding to the amplified coherent laser beams converge (konvergieren) to form an interference pattern, wherein, in the beam convergence region, at least "beam parts / beam shares" (Strahlanteile) of different and / or adjacent output laser beams converge.

[0006] Using the laser system and the interference pattern formed, laser processing of a workpiece can be carried out according to the principle of direct laser interference structuring, also referred to as Direct Laser Interference Patterning (DLIP).

[0007] For example, laser processing of a workpiece is performed in the region of an outer side and / or surface of the workpiece using the provided interference pattern. For laser processing, the outer side or surface is loaded with the interference pattern in order to produce a surface material modification with predetermined properties. For example, by loading the outer side of the workpiece with the interference pattern, material can be removed or a depression or "dimple-like" structure can be produced.

[0008] Using the laser system according to the present invention, for example, a workpiece formed of or including a glass material and / or a plastic material and / or a metal material can be processed.

[0009] The laser system according to the invention makes it possible, for example, to split an input laser beam provided by a laser beam source into a plurality of coherent laser beams and then to amplify the individual coherent laser beams, and in particular to amplify the coherent laser beams separately from one another in space. For example, separate amplification elements can be used to amplify the coherent laser beams. This enables the amplified coherent laser beams, based on which the output laser beam is formed, to be flexibly positioned and oriented in space.

[0010] “At least beam sections of different and / or adjacent output laser beams converge” is to be understood as meaning that sections of different output laser beams or different output laser beams converge and / or converge towards each other to form an interference pattern. More precisely, the Poynting vectors assigned to the sections of different output laser beams converge or the Poynting vectors assigned to different output laser beams converge.

[0011] The coherent laser beam and / or the amplified coherent laser beam and / or the output laser beam is in particular in the form of a sum of sub-beams and / or a beam cluster with a specific spatial extension. In particular, the beam cluster or the sub-beams are each assigned a Poynting vector with a specific direction or are each assigned several Poynting vectors with different directions.

[0012] Different output laser beams are to be understood in particular as output laser beams which are formed and / or obtained from different and / or adjacent amplified coherent laser beams.

[0013] In particular, it can be provided that the phase adjustment device and the amplification device and / or the beam splitting device of the laser system are designed as separate components of the laser system.

[0014] In particular, the coherent laser beam and / or the amplified coherent laser beam is guided at least in sections in an optical waveguide and in particular in a single-core waveguide within the laser system. In particular, the coherent laser beam is guided between the beam splitter and the phase adjustment device and / or between the phase adjustment device and the amplifier element in an optical waveguide and in particular in a single-core waveguide, respectively. This enables, in particular, the amplified coherent laser beam and / or the output laser beam to be positioned and / or oriented particularly flexibly.

[0015] In particular, it can be provided that mutually adjacent output laser beams present in the beam convergence region have at least beam sections which enclose an angle of at least 0.2° and / or at most 40° and preferably at least 1° and / or at most 5°. This allows the formation of an interference pattern in a technically simple manner.

[0016] Mutually adjacent output laser beams are to be understood as output laser beams directly adjacent to each other and / or output laser beams closest to each other and / or output beams of neighbors closest to each other. In particular, no further output laser beams are arranged between mutually adjacent output laser beams.

[0017] In particular, it can be provided that, in the region of beam convergence, mutually adjacent output laser beams have beam sections which enclose a first, non-zero angle assigned to the first angular coordinate, wherein the first angle is at least 0.2° and / or at most 40° and preferably at least 1° and / or at most 5°. This allows, for example, two-dimensional formation of interference patterns.

[0018] It can be provided that in the region of beam convergence, mutually adjacent outgoing laser beams have beam sections which enclose a second, non-zero angle assigned to a second angular coordinate different from the first angular coordinate, wherein the second angle is at least 0.2° and / or at most 40° and preferably at least 1° and / or at most 5°. In this case, in particular, both adjacent outgoing laser beams enclosing a first, non-zero angle with respect to one another and outgoing laser beams enclosing a second, non-zero angle with respect to one another are present in the region of beam convergence.

[0019] “Beam sections of adjacent output laser beams enclose a non-zero angle” is to be understood as meaning that the Poynting vectors assigned to at least the beam sections of adjacent output laser beams enclose the aforementioned non-zero first angle or second angle relative to each other.

[0020] The first angle extends in a first direction and / or about a first angular coordinate. The second angle extends in particular in a second direction and / or about a second angular coordinate (with reference to a specific output laser beam, the first angle and the second angle relative to adjacent output laser beams are measured with reference to the specific output laser beam as a starting point). The second direction or the second angular coordinate is different from the first direction or the first angular coordinate of the first angle α. In particular, the first direction or the first angular coordinate is oriented transversely or perpendicularly to the second direction or the second angular coordinate.

[0021] For example, when describing the orientation of the output laser beam in spherical coordinates, the first angle corresponds to the polar angle and the second angle β corresponds to the azimuthal angle.

[0022] In particular, it can be provided that adjacent output laser beams present in the beam convergence region and in particular all adjacent output laser beams present in the beam convergence region are oriented relative to one another in such a way that in each case two adjacent output laser beams either have beam portions which enclose a non-zero first angle or have beam portions which enclose a non-zero second angle. In this case, in particular, in each case two adjacent output laser beams which enclose a non-zero first angle have a second angle of zero or, conversely, in each case two adjacent output laser beams which enclose a non-zero second angle have a first angle of zero. This can be achieved, for example, in that a two-dimensional array of amplified coherent laser beams is incident on a focusing device to form the output laser beams.

[0023] In particular, it can be provided that the output laser beam is present in the beam convergence region as a collimated beam bundle and / or a plane wave. In particular, the output laser beam is a collimated Gaussian beam or a collimated Gaussian-like beam in the beam convergence region.

[0024] In particular, the corresponding output laser beam does not exist as a converging beam in the beam convergence region. This means that a particular output laser beam does not have converging beam portions and / or sub-beams. In particular, a particular output laser beam is not focused to a point.

[0025] Each output laser beam is then assigned a unique Poynting vector with a unique orientation. The corresponding Poynting vector is then used as a reference for specifying the first angle and / or the second angle between two adjacent output laser beams. In particular, in this case, the Poynting vector of a specific output laser beam corresponds to the main propagation direction of the output laser beam.

[0026] In particular, when the output laser beams exist as a collimated beam cluster, the output laser beams converge toward each other in a beam convergence region to form an interference pattern, wherein output laser beams adjacent to each other in the beam convergence region enclose a non-zero first angle assigned to a first angular coordinate, and / or output laser beams adjacent to each other in the beam convergence region enclose a non-zero second angle assigned to a second angular coordinate.

[0027] Alternatively, it can be provided that the output laser beam is present in the beam convergence region as a diverging beam bundle and / or a spherical wave and / or a partial spherical wave. A partial spherical wave is a geometrical sub-region and / or a part of a spherical wave.

[0028] Each output laser beam is then assigned in particular a plurality of Poynting vectors, wherein the direction of the Poynting vectors is different for different beam sections of a particular output laser beam. The Poynting vectors are then used as a reference for specifying the first angle and / or the second angle between beam sections of two adjacent output laser beams. The main propagation direction of a particular output laser beam then corresponds in particular to the average direction of all non-zero Poynting vectors of the output laser beam.

[0029] In the case of the output laser beams being present as diverging beam clusters, these output laser beams in particular have only beam portions which converge towards each other in the beam convergence region to form an interference pattern, wherein in the beam convergence region only beam portions of mutually adjacent output laser beams enclose a first non-zero angle assigned to a first angular coordinate, and / or wherein in the beam convergence region only beam portions of mutually adjacent output laser beams enclose a second non-zero angle assigned to a second angular coordinate. In particular, in this case, adjacent output laser beams also have further beam portions which do not converge towards each other and / or do not enclose the first angle and / or the second angle.

[0030] The output laser beam is formed in particular by collimation and / or deflection of the amplified coherent laser beam. In particular, the deflection takes place in such a way that the output laser beam converges to form an interference pattern.

[0031] The amplified coherent laser beam coupled out of the amplifier device and / or coupled out of the amplifier element of the amplifier device is present in particular as a diverging beam bundle and / or a spherical wave and / or a partial spherical wave.

[0032] Advantageously, the laser system has a focusing device for collimating and / or deflecting the amplified coherent laser beam incident on the focusing device. For example, this enables the amplified coherent laser beam present as a divergent beam cluster to be collimated so as to provide a collimated output laser beam.

[0033] In principle, the focusing device can have one or more focusing elements for collimating and / or deflecting the amplified coherent laser beam. For example, the focusing element is an F-theta objective or comprises an F-theta objective.

[0034] In one embodiment, the focusing device comprises a focusing element and in particular a single focusing element, wherein a plurality of amplified coherent laser beams and in particular all present amplified coherent laser beams are incident on the focusing element and wherein the amplified coherent laser beams are collimated and deflected by means of the focusing element in order to provide the output laser beam. This allows the laser system to be compact and have a reduced number of optical elements.

[0035] In particular, a positional deviation of the amplified coherent laser beam incident on the focusing element is converted into an angular deviation by means of the focusing element.

[0036] For example, adjacent amplified coherent laser beams incident on the focusing element are positioned with a positional offset with respect to a first spatial direction and / or with respect to a second spatial direction, wherein the second spatial direction is oriented transversely and in particular perpendicularly to the first spatial direction. From this positional offset, an angular offset between adjacent outgoing laser beams is then formed by means of the focusing element. These outgoing laser beams correspond in particular to the outgoing laser beams. Thus, an angle and / or a first angle and / or a second angle can be formed between the outgoing laser beams.

[0037] For example, adjacent amplified coherent laser beams incident on the focusing element are positioned in a one-dimensional or two-dimensional array with respect to the first spatial direction and / or the second spatial direction.

[0038] In a further embodiment, the focusing device has a plurality of focusing elements, wherein each of the amplified coherent laser beams is assigned to a focusing element, and wherein each of the amplified coherent laser beams is collimated by means of the assigned focusing element.

[0039] In particular, then, the amplified coherent laser beams incident on the focusing element and emerging from the focusing element have the same main propagation direction. Adjacent amplified coherent laser beams incident on the focusing element and / or emerging from the focusing element have, for example, a position offset with respect to the first spatial direction and / or the second spatial direction and are in particular positioned as an array with respect to the first spatial direction and / or the second spatial direction.

[0040] In order to then deflect the amplified coherent laser beam emerging from the respective focusing element, a beam deflection device can in particular be provided in order to form an output laser beam which converges in a beam convergence region.

[0041] In one variant, it is provided that both the amplified coherent laser beam incident on the focusing element and the laser beam emerging from the focusing element are positioned in a convergent manner. Here, for example, the amplifying element and / or the focusing element of the amplifying device are positioned in a circular and / or spherical manner. This means that no separate beam deflection device is required.

[0042] In particular, it can be provided that the existing focusing element and / or the amplified coherent laser beam incident on the existing focusing element are configured and arranged in such a way that the laser beam emerging from the focusing element forms a beam convergence region and corresponds to the output laser beam. In particular, the laser beam emerging from the focusing element does not undergo further deflection and / or beam shaping.

[0043] In particular, it can be provided that the focusing element and / or the amplified coherent laser beam incident on the focusing element are configured and arranged such that the laser beam emerging from the focusing element converges to form an interference pattern. In particular, then, no separate beam deflection device is required. The emerging laser beam then forms a beam convergence region and corresponds to the output laser beam.

[0044] It can be arranged that the laser system has a beam deflection device for deflecting the amplified coherent laser beam so as to form an output laser beam that converges in the beam convergence region. The beam deflection device, for example, comprises a plurality of mirror elements, which are configured and arranged to deflect the amplified coherent laser beam entering the beam deflection device.

[0045] In one variant, it can be provided that the amplified coherent laser beam coupled out of the amplification device is present as a diverging beam cluster, wherein the main propagation directions of adjacent amplified coherent laser beams are oriented parallel or transversely, and wherein the amplified coherent laser beams correspond to the output laser beam. In this variant, by arranging adjacent coherent laser beams transversely relative to one another, it is possible, in particular, to increase the beam portion of the output laser beam that contributes to the formation of the interference pattern.

[0046] In particular, it can be provided that the interference pattern has at least one interference element for laser processing of a workpiece, which interference element is repeated within the interference pattern and in particular is repeated at regular distances and in particular is repeated at equal distances. For example, this enables the creation of regular and / or periodic structures on the workpiece.

[0047] In principle, interference patterns can be constructed in one, two or three dimensions. For example, the interference elements are repeated in one, two or three spatial dimensions.

[0048] For example, the interference element is at least one focus point and / or at least one focus line or a pattern comprising at least one focus point and / or at least one focus line, such as points and / or lines, which are used for laser processing of a workpiece and in particular have an intensity higher than a threshold required for performing laser processing of a workpiece.

[0049] It may be advantageous if the interference element is repeated within the interference pattern at least 10 times and in particular at least 100 times and in particular at least 1000 times. This enables large-area periodic structures to be created on a workpiece in one or a small number of working steps.

[0050] In particular, it can be provided that the phase adjustment device is configured to adjust the phase difference between all existing coherent laser beams, and in particular to adjust the phase difference separately and independently. In particular, the phase adjustment device is configured to adjust the phase position of each coherent laser beam individually.

[0051] In particular, the phase adjustment device comprises a plurality of phase adjustment elements, wherein preferably one phase adjustment element is associated with each coherent laser beam. The phase position of a particular coherent laser beam can then be adjusted, for example, by means of the phase adjustment element associated with the particular coherent laser beam.

[0052] It can be advantageous if at least one property of the interference pattern and / or the interference elements is variable or altered by setting and / or controlling the phase difference between the coherent laser beams by means of a phase setting device. This enables, for example, dynamic machining of workpieces. This also makes it technically easy to adapt the interference pattern to different applications.

[0053] The at least one property comprises, in particular, the distance between the interference elements and / or the periodicity of the interference elements and / or the peak intensity of the interference elements and / or the intensity distribution of the interference elements and / or the geometry of the interference elements.

[0054] For example, it can be provided that during operation of the laser system at least a subset of the interference elements of the interference pattern are moved relative to the workpiece and / or scanned over the workpiece by controlling, and in particular only by controlling, phase differences between the coherent laser beams.

[0055] In particular, it can be provided that the interference pattern extends over an extent of at least 0.5 mm and preferably at least 1 mm and in particular preferably at least 2 mm with respect to at least one spatial direction. For example, the interference pattern extends over an extent of at most 10 mm in at least one spatial direction.

[0056] In particular, the interference pattern is uniform or quasi-uniform over its extent with respect to its properties, such as, for example, the peak intensity and / or the intensity distribution and / or the geometry of the interference elements of the interference pattern.

[0057] In particular, the interference pattern is constructed statically in time (with parameters that are static in time and are related to the corresponding phase differences between the coherent laser beams). In particular, the interference pattern is completely formed with respect to its extension at a specific point in time. In particular, all interference elements of the interference pattern are present at the same time.

[0058] It can be advantageous if the amplification device is arranged downstream of the phase adjustment device with respect to the main propagation direction of the coherent laser beams. In particular, the corresponding phase differences between the coherent laser beams can thereby be adjusted by means of the phase adjustment device at a lower power (compared to the power of the amplified coherent laser beams). This allows the phase adjustment device to be realized more simply in terms of technology.

[0059] However, it is also possible in principle to arrange the phase adjustment device downstream of the amplification device.

[0060] It can be advantageous if the amplification device has a plurality of amplification elements for amplifying the corresponding coherent laser beams and is particularly characterized in that the amplification elements are rod-shaped and / or are designed as fiber amplifiers. The amplification elements can be arranged in particular in a geometrically flexible manner. For example, they can be arranged in an array. This allows the amplified coherent laser beams coupled out of the amplification elements to be geometrically flexible and simple to position and orient.

[0061] In particular, the amplifier elements are each associated with a specific coherent laser beam. In particular, the main propagation direction of the amplified coherent laser beam coupled out of the corresponding amplifier element is oriented parallel to the main direction and / or the longitudinal center axis of the amplifier element.

[0062] In particular, it can be provided that the amplifier device is designed to adjust the output power of the corresponding amplified coherent laser beam, and in particular to adjust the output power of each amplified coherent laser beam individually. For example, the output power of a specific amplified coherent laser beam can be adjusted by means of an amplifier element assigned to the specific amplified coherent laser beam.

[0063] Preferably, the output power can then be controlled from zero to a maximum value.By selecting an output power of zero, the corresponding amplified coherent laser beam and in particular the output laser beam formed therefrom can be deactivated so that said laser beam no longer participates in forming the interference pattern.

[0064] It may be advantageous if the laser system has a beam splitting device for splitting an input laser beam provided by the laser beam source into a plurality of coherent laser beams. For example, this enables the use of a single laser beam source to provide the coherent laser beams present.

[0065] In principle, it is also possible for the laser system to have a plurality of laser beam sources, wherein one or more coherent laser beams are provided by means of each laser beam source.

[0066] In particular, it can be provided that the laser system has a feed device for adjusting the position and / or orientation of the workpiece relative to the interference pattern. In particular, the feed device is configured to perform a movement of the workpiece relative to the interference pattern.

[0067] In particular, the workpiece can be arranged and / or fixed to a workpiece holder of a laser system in order to perform laser processing.

[0068] The laser beam source in particular provides pulsed laser radiation, and in particular ultrashort pulsed laser radiation. In particular, the input laser beam and / or the coherent laser beam and / or the amplified coherent laser beam and / or the output laser beam provided by the laser beam source is a pulsed laser beam, and in particular an ultrashort pulsed laser beam.

[0069] According to the present invention, in the method mentioned at the beginning, it is arranged that a plurality of coherent laser beams are provided by means of at least one laser beam source, amplified coherent laser beams are formed by amplifying the coherent laser beams by means of an amplifying device, and corresponding phase differences between the coherent laser beams are adjusted by means of a phase adjusting device, and output laser beams based on or corresponding to the amplified coherent laser beams are formed, the output laser beams converge in a beam convergence region to form an interference pattern, wherein, in the beam convergence region, at least beam portions of different output laser beams converge.

[0070] The method according to the invention has in particular one or more further features and / or advantages of the laser system according to the invention. Advantageous embodiments have been described in conjunction with the laser system.

[0071] The method according to the invention can be carried out in particular by means of a laser system according to the invention. In particular, the method according to the invention is carried out by means of a laser system according to the invention.

[0072] Here, the first device and / or the first element of the laser system is arranged downstream of the second device and / or the second element of the laser system, which is to be understood as follows: the laser beam guided in the laser system, for example the input laser beam and / or the coherent laser beam and / or the amplified coherent laser beam, first impinges on the second device and / or the second element and then on the first device and / or the first element. The second device and / or the second element is then arranged upstream of the first device and / or the first element. These statements are always related to the main propagation direction of the corresponding laser beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The following description of the preferred embodiments is used to explain the present invention in more detail with reference to the accompanying drawings.

[0074] In the accompanying drawings it is shown:

[0075] Figure 1 A schematic representation of an embodiment of a laser system is shown, wherein a beam path in a first cross-sectional plane is schematically illustrated;

[0076] Figure 2 Shown according to Figure 1Schematic representation of a portion of a laser system of , wherein a beam path in a second section plane oriented perpendicular to the first section plane is schematically illustrated;

[0077] Figure 3 An embodiment of a laser system having a focusing element for collimating and deflecting an amplified coherent laser beam is shown.

[0078] Schematic representation of a part;

[0079] Figure 4 shows a schematic representation of a portion of an embodiment of a laser system having a plurality of focusing elements for collimating an amplified coherent laser beam and a beam deflecting device for deflecting the amplified coherent laser beam;

[0080] Figure 5 shows a schematic representation of a portion of another embodiment of a laser system having multiple focusing elements;

[0081] Figure 6 shows a schematic representation of a portion of an embodiment of a laser system without a focusing element;

[0082] Figure 7 shows a schematic representation of a portion of another embodiment of a laser system without a focusing element;

[0083] Figures 8a to 8c Grayscale images at different scales showing examples of interference patterns intended for laser processing of a workpiece;

[0084] Figures 9a to 9c shows a grayscale image at different scales of another example of an interference pattern intended for laser processing of a workpiece;

[0085] as well as

[0086] Fig.10 A grayscale image of another example of an interference pattern intended for laser machining of a workpiece is shown.

[0087] In all the figures, elements which are identical or have equivalent functions are provided with the same reference signs. DETAILED DESCRIPTION

[0088] exist Figure 1 , Figure 2 and Figure 3Schematically, an embodiment of a laser system is shown in FIG. 1 and is denoted in the figure by 100. During operation of the laser system 100, a plurality of output laser beams 102 are provided, which form an interference pattern, which is provided for laser processing of a workpiece 104. The interference pattern formed is based in particular on the principle of Direct Laser Interference Patterning (DLIP).

[0089] In the exemplary embodiment shown, the laser system 100 comprises a laser beam source 106 , by means of which an input laser beam 108 is provided, wherein the input laser beam 108 is split into a plurality of coherent laser beams 112 by means of a beam splitting device 110 .

[0090] The laser beams provided by the laser beam source 106 (eg, the input laser beam 108 and / or the coherent laser beam 112) are, for example, linearly polarized laser beams. In particular, these laser beams have high beam quality, wherein the beam quality factor and / or M 2 The value is less than 1.5.

[0091] In particular, each of the coherent laser beams 112 has an average power in the range of 10 W to 500 W.

[0092] In particular, the laser beams provided by the laser beam source 106 are pulsed laser beams, wherein the laser pulses of these laser beams preferably have a pulse duration between 10 ps and 1000 ps and / or a repetition rate between 100 kHz and 1 MHz.

[0093] The beam splitting device 110 can be realized, for example, using optical fibers and / or include at least one optical fiber beam splitter. An optical fiber beam splitter includes, for example, an input waveguide to which, on the output side, further waveguides for beam splitting are connected, in particular by splicing.

[0094] In principle, it is also possible for a plurality of laser beam sources 106 to be present for providing these coherent laser beams 112. In this case, for example, one or more coherent laser beams 112 are provided by means of a respective laser beam source 106.

[0095] The coherent laser beam 112 coupled out of the beam splitting device 110 is preferably guided in an optical waveguide and / or an optical fiber, wherein the coherent laser beam 112 can be guided, for example, in a single-core waveguide, such as in Figure 1 In principle, a multi-core waveguide can also be provided to guide the coherent laser beam 112.

[0096] In order to adjust the corresponding phase differences between the individual coherent laser beams 112, a phase adjustment device 114 is provided, which preferably comprises a plurality of phase adjustment elements 116. By means of a specific phase adjustment element 116, the phase of the coherent laser beam 112 assigned to this specific phase adjustment element can be adjusted.

[0097] For example, a plurality of or all coherent laser beams 112 are each assigned a phase adjustment element 116. In the case of N coherent laser beams 112, the phase adjustment device 114 comprises, for example, N-1 or N phase adjustment elements 116. In particular, this enables the corresponding phase differences between all coherent laser beams 112 present to be adjusted.

[0098] The phase setting device 114 and / or the phase setting element 116 may, for example, be integrated into an optical waveguide guiding the coherent laser beam 112 .

[0099] In order to amplify the corresponding coherent laser beam 112, the laser system 100 includes an amplification device 118, which preferably includes a plurality of amplification elements 120. For example, each of these amplification elements 120 is assigned to a specific coherent laser beam 112. By amplifying the coherent laser beam 112 by means of the amplification device 118, an amplified coherent laser beam 113 is formed.

[0100] The amplifier device 118 or the amplifier element 120 is arranged downstream of the phase adjustment device 114 or the phase adjustment element 116 with respect to the main propagation direction 122 , ie the corresponding coherent laser beam 112 first passes through the phase adjustment element 116 and then through the amplifier element 120 .

[0101] The main propagation direction 122 is to be understood as the main direction and / or average direction along which the input laser beam 108 or the coherent laser beam 112 or the amplified coherent laser beam 113 or the output laser beam 102 propagates through the laser system 100. In particular, the respective main propagation direction 122 corresponds to the main direction and / or average direction of the Poynting vector associated with the respective laser beam.

[0102] In particular, the coherent laser beams 112 coupled out of the phase adjustment device 114 are coupled into the amplification device 118. In particular, before the coherent laser beams 112 are coupled into the amplification device 118, the phase adjustment device 114 is used to adjust the corresponding phase differences between the coherent laser beams.

[0103] In particular, the amplifying elements 120 can be arranged and / or oriented individually and / or spatially separated relative to one another. The amplifying elements 120 are, for example, rod-shaped and / or are designed as fiber amplifiers. For example, the amplifying element 120 is or comprises a "rod-type photonic crystal fiber amplifier", for example as known from J. Limpert et al., "High-power rod-type photonic crystal fiber laser", Opt. Express 13, 1055 to 1058 (2005).

[0104] It is also possible for the amplifier device 118 and / or the amplifier element 120 to be designed as a multicore waveguide and / or to be integrated into a multicore waveguide. The individual coherent laser beams 112 and / or the amplified coherent laser beams 113 are then separated from one another, in particular in the far field.

[0105] All amplifier elements 120 present are advantageously designed in the same manner and / or as identical components.

[0106] The output laser beam 102 of the laser system 100 is to be understood as a coherent laser beam which, during operation of the laser system 100, is amplified by the amplification device 118 and is constructed and / or configured such that it forms an interference pattern 124 provided for laser processing of the workpiece 104. The output laser beam 102 is therefore a laser beam which contributes and / or is configured to form the interference pattern 124.

[0107] The output laser beam 102 converges toward the interference pattern 124 and / or converges from different directions. The output laser beam 102 extends in particular in a beam convergence region 130 of the laser system 100 associated with the interference pattern 124 or forms the beam convergence region 130 of the laser system 100 associated with the interference pattern 124.

[0108] Therefore, the output laser beam 102 is a laser beam that contributes to the formation of the interference pattern 124. Depending on the embodiment, the output laser beam 102 is based on the coherent laser beam 113 amplified by the amplification device 118 or corresponds to the coherent laser beam 113 amplified by the amplification device 118.

[0109] The interference pattern 124 formed by means of the provided output laser beam 102 extends, for example, in a plane or in a three-dimensional volume.

[0110] The workpiece 104 is configured to be loaded with the interference pattern 124 for laser processing. The laser system 100 may have a workpiece holder 126 on which the workpiece 104 may be arranged and / or fixed so as to be loaded with the interference pattern 124 .

[0111] Furthermore, the laser system 100 may have a feeding device 128, which is configured to adjust the position and / or orientation of the workpiece 104 relative to the interference pattern 124, and / or is configured to perform a movement of the workpiece 104 relative to the interference pattern 124. For example, the feeding device 128 is configured to move the workpiece holder 126 and the workpiece 104 arranged thereon relative to the interference pattern 124, and in particular to move the workpiece holder and the workpiece along a predetermined trajectory.

[0112] To form the interference pattern 124, it is necessary that the output laser beams 102 that contribute to forming the interference pattern are directed to converge with each other and have a non-zero angle relative to each other. More specifically, the corresponding main propagation directions 122 and / or Poynting vectors 132 of adjacent output laser beams 102 have a non-zero angle relative to each other.

[0113] In a first variation of the laser system 100, all output laser beams 102 are arranged in a common plane or face (see, for example, Figure 1 The three output laser beams 102 are shown, wherein adjacent output laser beams 102 form a non-zero first angle α relative to each other and converge with each other at the first angle α, that is, adjacent output laser beams 102 converge with each other at the first angle α in the direction of the interference pattern 124 to be formed.

[0114] The first angle α extends in particular in a first direction and / or about a first angular coordinate.

[0115] The interference pattern 124 obtained in this case extends two-dimensionally in the common plane of the outgoing laser beams 102 and in particular only in this plane ( Figure 1 Extends in the zx plane in the example shown.

[0116] In accordance with Figure 1 In the example of , the first variant is achieved as follows: the amplified coherent laser beams 113 emitted from the amplifying elements 120 are positioned to be spaced apart from each other in the first spatial direction x and are coupled into the focusing device 134 of the laser system 100. The focusing device 134 has one or more focusing elements 136, which respectively include focusing optics and / or F-theta objectives or are constructed as focusing optics and / or F-theta objectives. The amplified coherent laser beams 113 incident on the focusing device 134 extend, for example, parallel to each other and / or in a plane parallel to the first spatial direction x. For example, the amplifying elements 120 and / or the amplified coherent laser beams 113 emitted therefrom are arranged in an array with respect to the first spatial direction x.

[0117] The amplified coherent laser beam 113 emerges from the corresponding amplifying element 120, in particular as a divergent beam cluster 138 and / or a spherical wave or at least as a sub-region of a spherical wave (e.g. at Figure 6 1 (simplified in FIG. 1 ), and in this form are incident on the focusing device 134. The focusing device 134 is configured to collimate the corresponding amplified coherent laser beam 113 incident thereon. The output laser beams 102 formed by an amplified coherent laser beam 113 incident on the focusing device 134 are respectively emitted from the focusing device 134 as collimated beam clusters 140 and / or plane waves (for example, at Figure 3 (in brief).

[0118] exist Figure 1 , Figure 2 and Figure 3 In the example shown, all existing amplified coherent laser beams 113 are provided with a single focusing element 136. Adjacent amplified coherent laser beams 113 strike the focusing element 136 with a positional offset relative to the first spatial direction x, wherein the positional offset causes an angular offset between the output laser beams 102 formed by the amplified coherent laser beams 113 downstream of the focusing element 136 in the form of the first angle α between adjacent output laser beams 102.

[0119] The position offset of the amplified coherent laser beam 113 and / or the resulting first angle α may be the same for all amplified coherent laser beams 113 and / or the output laser beam 102 or may be the same for a subset of the amplified coherent laser beams and / or the output laser beam. However, it is also possible that the position offset and / or the first angle α between different adjacent amplified coherent laser beams 113 and / or the output laser beam 102 are selected differently.

[0120] In a second variant, there are multiple planes or surfaces in which the existing output laser beams 102 extend, wherein, in particular, different subsets of the output laser beams 102 are respectively assigned to different planes. The output laser beams 102 assigned to a specific subset then extend in the same plane or surface.

[0121] In accordance with Figure 1 , Figure 2 and Figure 3 In the example of , the second variant can be realized in that there are both amplified coherent laser beams 113 spaced apart from each other in a first spatial direction x and amplified coherent laser beams 113 spaced apart from each other in a second spatial direction y oriented transversely and in particular perpendicularly to the first spatial direction x. For example, the amplifying elements 120 and / or the amplified coherent laser beams 113 emitted therefrom are arranged in a two-dimensional array with respect to the first spatial direction x and the second spatial direction y.

[0122] Then, there are two output laser beams 102 ( Figure 1 ); and adjacent output laser beams 102 ( Figure 2 ).

[0123] The second angle β extends in particular in a second direction and / or about a second angular coordinate (with reference to a specific output laser beam 102, the first angle α and / or the second angle β are measured relative to an adjacent output laser beam 102 starting from the specific output laser beam). The second direction and / or the second angular coordinate are different from the first direction and / or the first angular coordinate of the first angle α. In particular, the first direction is oriented transversely or perpendicularly to the second direction.

[0124] For example, when describing the orientation of the output laser beam 102 in spherical coordinates, the first angle α corresponds to the polar angle and the second angle β corresponds to the azimuthal angle.

[0125] In the case of the second modification, the interference pattern 124 formed in the space (at Figure 1 In the example shown, it extends three-dimensionally in all three spatial directions (x, y and z).

[0126] Therefore, in the above-mentioned variant, the output laser beam 102 extending convergently in the beam convergence region 130 is achieved by means of the position shift of the amplified coherent laser beam 113 incident on the focusing element 136 and the resulting angular shift in the form of the first angle α and / or the second angle β.

[0127] In order to form the interference pattern 124, the angular offset between adjacent output laser beams must be within a certain range. The theoretically possible range in which the formation of the interference pattern 124 can occur is between 2° and 180°. Preferably, the first angle α and / or the second angle β have a value between 15° and 25°.

[0128] Figure 4 The example shown differs from the above examples in that the focusing device 134 includes a plurality of focusing elements 136 and the laser system 100 has a beam deflection device 142 to form an angular offset between the output laser beams 102. In other respects, the example has the same structure and / or working method as the above examples.

[0129] In the example shown, a focusing element 136 and in particular a single focusing element 136 is assigned to each of the amplification elements 120 and / or each of the amplified coherent laser beams 113 emerging from the amplification elements 120 .

[0130] The amplified coherent laser beam 113 emerges from the correspondingly assigned amplifying element 120 as a diverging beam bundle 138 and is converted into a collimated beam bundle 140 by means of a focusing element 136. The amplified coherent laser beams 113 emerging from the corresponding focusing element 136 are oriented parallel to one another, for example.

[0131] In this example, the focusing device 134 and / or the focusing element 136 therefore causes a collimation of the corresponding amplified coherent laser beam 113 and in particular does not cause a focusing thereof.

[0132] In order to form an output laser beam 102 that converges in the beam convergence region 130 and forms the interference pattern 124, the amplified coherent laser beam 113 emitted from the focusing element 136 is coupled into the beam deflection device 142. The beam deflection device is configured to form an output laser beam 102 having the above-mentioned angular offset from the coupled amplified coherent laser beam 113. Then, adjacent output laser beams 102 are directed to converge with each other and have a non-zero first angle α and / or a second angle β relative to each other.

[0133] The beam deflection device 142 can, for example, have a plurality of mirror elements 144 which are configured and arranged such that a converging output laser beam 102 is formed from the coupled-in amplified coherent laser beams 113 which are oriented, for example, parallel to one another.

[0134] exist Figure 5 In the example shown, according to Figure 4 The focusing device 134 has a plurality of focusing elements 136, wherein a specific focusing element 136 causes the amplified coherent laser beam 113 assigned to the specific focusing element 136 to be collimated. For example, one focusing element 136 is assigned to each amplifying element 120.

[0135] The focusing element 136 and / or the amplified coherent laser beam 113 impinging on the focusing element 136 are configured and arranged such that the laser beams emerging from the focusing element 136 already extend convergently relative to one another and have the angular offset relative to one another in order to form the interference pattern 124. These emerging laser beams thus correspond to the output laser beam 102 or have the characteristics of the output laser beam 102.

[0136] For example, the amplifying element 120 is arranged and / or configured such that the coherent laser beam 120 coupled out of it and impinging on the focusing element 136 already has the angular offset in the form of the first angle α and / or the second angle β. Accordingly, in this example, the output laser beams 102 coupled out of the focusing element 136 have an angular offset relative to each other so as to form the interference pattern 124.

[0137] The amplifying elements 120 are, for example, configured in a rod-shaped manner and / or as a “rod-type photonic crystal fiber amplifier”, wherein the corresponding main propagation direction 122 of the amplified coherent laser beam 113 emerging from a particular amplifying element 120 is parallel or at least approximately parallel to the longitudinal center axis 146 of the amplifying element 120. For example, the longitudinal center axes 146 of adjacent amplifying elements 120 are then oriented with an angular offset in the form of a first angle α and / or a second angle β relative to one another. The corresponding center points of the amplifying elements 120 are positioned, for example, in a circular and / or spherical manner.

[0138] In accordance with Figures 1 to 5 In the above-described embodiments, the output laser beam 102 is respectively present as a collimated beam cluster 140 and / or in the form of a plane wave. In this case, the output laser beam 102 is respectively assigned exactly one Poynting vector 132 corresponding to the main propagation direction 122. In this case, the Poynting vector 132 is a globally uniform characteristic of the corresponding collimated output laser beam 102.

[0139] exist Figure 6 and Figure 7 In the embodiment of the laser system 100 shown, the output laser beam 102 configured to form the interference pattern 124 is provided in the form of a diverging beam cluster 138 and / or a spherical wave. In this case, the Poynting vector 132 is always oriented perpendicularly to the direction of the wavefront of the spherical wave of the specific output laser beam 102 and is therefore oriented differently locally (at Figure 6 ). That is, the non-zero Poynting vectors 132 assigned to a specific output laser beam 102 cover a specific angular region. Then, the main propagation direction 122 of the output laser beam 102 is to be understood as the average direction of all non-zero Poynting vectors 132.

[0140] The amplifying element 120 is arranged and / or configured such that at least a beam portion of an adjacent laser beam coupled out therefrom has a Poynting vector 132 having an angular offset in the form of a first angle α and / or a second angle β.

[0141] For example, the amplifying element 120 is arranged and / or configured such that the output laser beam 102 coupled out of it and impinging on the focusing element 136 already has the aforementioned angular offset in the form of the first angle α and / or the second angle β. Accordingly, in this example, the beam portions of the output laser beam 102 coupled out of the focusing element 136 have a suitable angular offset relative to each other in order to form the interference pattern 124. Therefore, in this case, these laser beams emitted from the amplifying element 120 correspond to the output laser beam 102, or at least partially have the characteristics required for forming the interference pattern 124.

[0142] In particular, according to Figure 6 and Figure 7 In the embodiment of the present invention, the focusing device 134 and / or the focusing element 136 for collimating the laser beam emitted from the amplifying element 120 are not provided.

[0143] exist Figure 6 In the example shown, the longitudinal center axes 146 of the amplifying element 120 and / or the main propagation directions 122 of adjacent output laser beams 102 are oriented parallel or at least approximately parallel. In order to increase the corresponding beam portions of adjacent output laser beams 102 having a suitable angular offset in the form of the first angle α and / or the second angle β in order to form the interference pattern 124, the respective main propagation directions 122 of adjacent output laser beams 102 can be converged to each other at a certain angle ( Figure 7 ). The main propagation directions 122 of adjacent output laser beams 102 then have a non-zero first angle α and / or a second angle β relative to each other which may be, for example, between 1° and 180°.

[0144] A first example of an interference pattern 124 formed by the laser system 100 is Figure 8a , Figure 8b and Figure 8c , where lighter gray values ​​represent higher intensities. The interference pattern 124 has multiple repeated interference elements 150 in at least one spatial direction x, y, z, wherein the repeated interference elements 150 are spaced apart from one another in the at least one spatial direction and are arranged adjacent to one another, in particular at the same distance from one another. Figures 8a to 8c In the example shown, the interference element 150 is designed as a single point and / or focus.

[0145] For example, the interference element 150 is repeated in a planar manner in a first spatial direction x and a second spatial direction y, or in all three spatial directions as a three-dimensional volume. The interference element 150 forms, in particular, the interference pattern 124 .

[0146] exist Figures 9a to 9cIn the example shown, the interference elements 150 are formed in a fringe pattern and / or as a single focused fringe.

[0147] exist Fig.10 In the example shown, the interference element 150 includes a dot pattern and / or a plurality of focal spots.

[0148] The laser system 100 works as follows:

[0149] During operation of the laser system 100 , an interference pattern 124 is formed by means of the output laser beam 102 , and a workpiece 124 arranged on a workpiece holder 126 is impinged upon by the interference pattern 124 for laser processing.

[0150] Typical applications may for example consist in performing large-area machining of the workpiece 104 on and / or in the region of the outer side 152 of the workpiece 104. For example, the interference pattern 124 may be used to create a periodic structure on the outer side 152 with predetermined properties.

[0151] It may be provided that the workpiece 124 is positioned and / or oriented relative to the interference pattern 124 and / or is moved relative to the interference pattern 124 by means of the feed device 128 for laser processing.

[0152] By changing the phase difference between the coherent laser beams 112 by means of the phase adjustment element 116, the phase difference between the amplified coherent laser beams 113 and / or between the output laser beams 102 can be changed accordingly. The properties of the interference pattern 124 and / or the interference elements 150 of the interference pattern 124 can thereby be adapted.

[0153] During operation of the laser system 100, the distance 154 between mutually adjacent interference elements 150 can be adapted, for example, by changing the phase difference by means of the phase adjustment element 116. Furthermore, for example, the periodicity of the interference elements 150, for example, the regularity of the positioning of the interference elements 150 can be adapted. Furthermore, for example, the intensity distribution and / or the geometry of the interference elements 150 can be adapted. For example, the interference elements 150 and / or selected interference elements 150 can be scanned over the workpiece 104 by controlling the phase difference and in particular only by controlling the phase difference by means of the phase adjustment element 116.

[0154] Reference numerals list

[0155] α First angle

[0156] β Second angle

[0157] x first spatial direction

[0158] y Second spatial direction

[0159] 100 Laser Systems

[0160] 102 Output laser beam

[0161] 104 Workpieces

[0162] 106 Laser beam source

[0163] 108 Input laser beam

[0164] 110 beam splitter

[0165] 112 Coherent laser beam

[0166] 113 Amplified coherent laser beam

[0167] 114 Phase adjustment device

[0168] 116 Phase adjustment element

[0169] 118 Amplification Device

[0170] 120 Amplifier

[0171] 122 Main propagation direction

[0172] 124 Interference Pattern

[0173] 126 Workpiece holder

[0174] 128 Feeding device

[0175] 130 Beam convergence area

[0176] 132 Poynting vector

[0177] 134 Focusing device

[0178] 136 Focusing element

[0179] 138 Diverging Beam Cluster

[0180] 140 Collimated beam cluster

[0181] 142 Beam Deflection Device

[0182] 144 reflector element

[0183] 146 longitudinal centerline

[0184] 148 Center Point

[0185] 150 Interference Elements

[0186] 152 outer side

[0187] 154 Distance

Claims

1. A laser system for laser processing a workpiece (104) by means of an interference pattern (124), the laser system comprising: At least one laser beam source (106) for providing a plurality of coherent laser beams (112); an amplifying device (118) for forming an amplified coherent laser beam (113) by amplifying the coherent laser beams (112); a phase adjusting device (114) for adjusting corresponding phase differences between the coherent laser beams (112) and / or the amplified coherent laser beams (113); and a beam converging region (130), in which an output laser beam (102) based on the amplified coherent laser beams (113) or corresponding to the amplified coherent laser beams (113) converges to form the interference pattern (104), wherein at least beam portions of different output laser beams (102) converge in the beam converging region (130).

2. The laser system according to claim 1, characterized in that Mutually adjacent output laser beams (102) present in the beam convergence region (130) have at least beam portions which enclose an angle (α, β) of at least 0.2° and / or at most 40° and preferably at least 1° and / or at most 5°.

3. The laser system according to claim 1 or 2, characterized in that: Output laser beams (102) adjacent to each other in the beam convergence region (130) have beam portions which enclose a non-zero first angle (α) assigned to a first angular coordinate, wherein the first angle (α) is at least 0.2° and / or at most 40° and preferably at least 1° and / or at most 5°.

4. The laser system according to claim 3, characterized in that Output laser beams (102) adjacent to each other in the beam convergence region (130) have beam portions which enclose a non-zero second angle (β) assigned to a second angular coordinate different from the first angular coordinate, wherein the second angle (β) is at least 0.2° and / or at most 40° and preferably at least 1° and / or at most 5°.

5. The laser system according to claim 4, characterized in that Adjacent output laser beams (102) present in the beam convergence region (130) are oriented relative to each other such that each two adjacent output laser beams (102) either have beam portions enclosing a non-zero first angle (α) or have beam portions enclosing a non-zero second angle (β).

6. The laser system according to any one of the preceding claims, characterized in that The output laser beam (102) exists as a collimated beam cluster (140) in the beam converging region (130), or the output laser beam (102) exists as a divergent beam cluster (138) in the beam converging region (130).

7. The laser system according to any one of the preceding claims, characterized in that A focusing device (134) is provided, which is used to collimate and / or deflect the amplified coherent laser beam (113) incident on the focusing device (134).

8. The laser system according to claim 7, characterized in that The focusing device (134) has a focusing element (136), and in particular a single focusing element (136), wherein a plurality of amplified coherent laser beams (113), and in particular all present amplified coherent laser beams, are incident on the focusing element (136), and wherein the amplified coherent laser beams (113) are collimated and deflected by means of the focusing element (136) in order to provide the output laser beam (102).

9. The laser system according to claim 7, characterized in that The focusing device (134) has a plurality of focusing elements (136), wherein each of the amplified coherent laser beams (113) is assigned a focusing element (136), and wherein the amplified coherent laser beams (113) are collimated by means of the assigned focusing element (136).

10. The laser system according to any one of claims 7 to 9, characterized in that The existing focusing element (136) and / or the amplified coherent laser beam (113) incident on the existing focusing element (136) are configured and arranged so that the laser beam emitted from the focusing element (136) forms the beam convergence region (130) and corresponds to the output laser beam (102).

11. The laser system according to any one of the preceding claims, characterized in that A beam deflecting device (142) is provided for deflecting the amplified coherent laser beam (113) so as to form the output laser beam (102) converging in the beam converging region (130).

12. The laser system according to any one of the preceding claims, characterized in that The amplified coherent laser beam (113) coupled out of the amplification device (118) is present as a diverging beam cluster (138), wherein the main propagation directions (122) of adjacent amplified coherent laser beams (113) are oriented parallel or transversely, and wherein the amplified coherent laser beam (113) corresponds to the output laser beam (102).

13. The laser system according to any one of the preceding claims, characterized in that The interference pattern (124) has at least one interference element (150) for laser processing of the workpiece (104), which interference element is repeated within the interference pattern (124) and in particular is repeated at regular distances (154).

14. The laser system according to claim 13, characterized in that The interference element (150) is repeated at least 10 times, and in particular at least 100 times, and in particular at least 1000 times within the interference pattern (124).

15. The laser system according to claim 13 or 14, characterized in that By adjusting the phase difference between the coherent laser beam (112) or the amplified coherent laser beam (113) by means of the phase adjustment device (114), at least one characteristic of the interference pattern (124) and / or the interference element (150) is variable or changed, wherein the at least one characteristic particularly includes the distance (154) between the interference elements (150) and / or the periodicity of the interference elements (150) and / or the peak intensity of the interference elements (150) and / or the intensity distribution of the interference elements (150) and / or the geometric shape of the interference elements (150).

16. The laser system according to any one of the preceding claims, characterized in that The amplification device (118) has a plurality of amplification elements (120) for amplifying corresponding coherent laser beams (112) and is particularly characterized in that the amplification elements (120) are configured in the form of rods and / or as fiber amplifiers.

17. A method for laser processing a workpiece by means of an interference pattern (124), in which method a plurality of coherent laser beams (112) are provided by means of at least one laser beam source (106), amplified coherent laser beams (113) are formed by amplifying the coherent laser beams (112) by means of an amplification device (118), and corresponding phase differences between the coherent laser beams (112) and / or the amplified coherent laser beams (113) are adjusted by means of a phase adjustment device (114), wherein: An output laser beam (102) based on or corresponding to the amplified coherent laser beam (113) is formed, the output laser beam converges in a beam convergence region (130) to form the interference pattern (124), wherein at least beam portions of different output laser beams (102) converge in the beam convergence region (130).

Images