DE102019116803A1 - Method and device for machining a workpiece - Google Patents

Abstract

The present invention relates to a method for processing at least one workpiece (110, 120), the workpiece (110, 120) being acted upon by a processing beam (2), preferably a pulsed laser beam, particularly preferably an ultrashort pulse laser beam, the processing beam (2 , 2 ', 2 ", 20, 22) is moved highly dynamically between at least two different spatial areas (220, 230) to form a process zone (200).

Description

Technical area

The present invention relates to a method for machining at least one workpiece with heat-accumulating processes, in particular for welding two workpieces by means of a machining beam, at least one of the workpieces being transparent to the machining beam. In particular, the invention also relates to the welding of two transparent workpieces such as glasses, ceramics or other crystalline or polymer-based materials using a pulsed laser beam.

State of the art

For laser welding workpieces made of transparent materials and in particular for welding workpieces made of glass or ceramics, it is known to use pulsed lasers and in particular ultrashort pulse lasers. The pulsed laser beam is focused in, on or below a workpiece in which the material of one or both of the workpieces of a process zone is melted due to the absorption of the laser energy and the gap between the two workpieces is bridged by the melt, so that in this way After the material has solidified again, a weld seam is formed between the two workpieces without any further use of material being necessary. In other words, welding takes place using the materials already present in the workpieces.

As a result of the transparency of at least one, both or all of the workpieces for the machining beam, welding can also be achieved in an area between the workpieces resting against one another. The processing beam is focused through one of the transparent workpieces between the workpieces so that the material can be melted at the interface between the workpieces.

When welding transparent materials together, the energy introduced into the process zone and the associated high temperatures within the material can lead to tensions and / or cracks, which can reduce the quality of the joined materials at least in the area of the weld seam.

It is therefore known to iteratively optimize laser welding processes for joining transparent materials, whereby different processing parameters such as the pulse duration and / or the pulse energy of the pulsed laser beam and / or the relative feed speed between the process zone or processing beam and the workpieces can be varied in order to achieve a subsequent quality control, for example by means of a microscope through microscopic examinations of the weld seams and the other areas of the joined workpieces after completion of the actual welding process to determine the quality level and then iteratively optimize the corresponding process parameters by varying them.

The processing beam is focused by appropriate optics and the associated beam shaping in the material of one of the workpieces, in both workpieces and / or in the area of an interface between the two adjacent workpieces, with the position and shape of the focus formed in this way Can be part of the optimization process.

One challenge in optimization is to reduce the stresses induced by the laser beam in the joint partners, which can prevent a stable connection between the joint partners.

Other laser machining processes based on heat accumulation such as the modification of workpiece surfaces or volumes as well as laser lift-off processes are also confronted with the problem of the stresses induced in the workpiece by the laser beam.

Presentation of the invention

Based on the prior art, it is an object of the present invention to provide a method and a device for performing the method for machining at least one workpiece, the method and the device intended to further improve the quality of the machined workpiece or the machined workpieces.

This object is achieved by a method with the features of claim 1. Advantageous further developments emerge from the dependent claims, the present description and the attached figures.

Accordingly, a method for processing at least one workpiece is proposed, the workpiece being acted upon by a processing beam, preferably a pulsed laser beam, particularly preferably an ultra-short pulse laser beam, the processing beam being highly dynamic to form a process zone is moved between at least two different spatial areas.

Due to the highly dynamic movement of the processing beam in at least two spatial areas of the process zone, it is possible to distribute the energy of the processing beam over a larger area or a larger volume of the material of the workpiece in order to prevent the occurrence of high temperature stresses in the material of the workpiece to reduce or distribute them and to achieve a more efficient processing of the material.

The purely local entry of thermal energy in a single focus into the material of the workpiece, known from the prior art, is thus distributed in a highly dynamic manner to a larger volume and / or a larger surface using the proposed method.

In the present case, the term process zone is understood to mean a limited material volume in the workpiece or a limited material volume which overlaps at least two workpieces and into which energy is entered by means of the laser pulses of the processing beam. An energy input thus takes place in the material volume forming the process zone, which leads to heat accumulation and thus to a material change in the material volume. The spatial areas into which the processing beam is moved are preferably so far apart that the respective foci do not overlap and therefore the conventional, purely local input of thermal energy is avoided. At the same time, however, the foci are so close to one another that the energy input through the processing beam moving into the different spatial areas leads to an energy accumulation in the process zone.

In other words, the individual spatial areas are spaced apart from one another, but coupled with one another to such an extent that heat accumulation is achieved.

For example, the material volume in the process zone can melt due to the accumulated heat input and, after renewed solidification, cause a permanent material change in the workpiece or in the workpieces.

The process zone can be defined accordingly by the positioning of the spatial areas into which the processing beam is moved. The process zone can move relative to the workpiece through a relative movement of the laser optics and the workpiece and / or by actively influencing the laser optics. This can be used to form a spatially extending material modification, for example to form a weld seam.

With the proposed method, inter alia, heat diffusion effects in the material of the workpiece or the workpieces can be better taken into account. In other words, the energy introduced into the process zone by means of the processing beam and thus the temperature increase can partially diffuse into the surrounding volumes of the workpiece while the workpiece is being exposed to the processing beam in another of the spatial areas of the process zone, so that the actual through the machining beam introduced focus resulting temperature gradient in the material of the workpiece is weakened and thus the occurrence of temperature stresses can be reduced.

The absorption behavior within the process zone or the melted material volume in the process zone depends on the intensity distribution and of course on the overall average laser energy input. The initial absorption of the laser energy by the material in the process zone initially takes place in the focus of the processing beam moved into the respective spatial area.

The process is based on the knowledge that in the laser processing of transparent materials, for example the welding of workpieces made of glass by means of the processing beams, for example pulsed laser beams, non-linear absorption effects can be achieved in the transparent material due to the high intensities that can be achieved in the respective beam focus. If corresponding repetition rates are used for the pulsed processing beam, the energy introduced into the separate spatial areas of the process zone by means of the respective pulses accumulates, so that the material melts locally due to corresponding heat accumulation effects. As a result, in the vicinity of the geometric focus of the machining beam moved into the respective spatial area, an absorbing plasma initially of the size of the respective focus volume is created.

However, increased absorption occurs on the plasma surface which delimits the process zone and in particular in the area of the plasma surface which is oriented in the direction of the respective processing beam impinging on the plasma and on which the processing beam strikes. The plasma volume can thus continue to generate energy due to the increased absorption of the machining beam and the resulting energy input into the plasma volume on the plasma surface absorb, so that the volume of the plasma can increase further, this increase in the plasma volume being directed mainly along the processing beam and extending in the direction of the beam source. In other words, the plasma can propagate in an elongated shape along the machining beam. From this, an elongated bubble formed by the plasma can be formed.

In this way, an absorption volume can be formed which can exceed the original focus volume many times over.

The nonlinear absorption of the machining beam by the plasma can result from the high electron temperature in the plasma. The electrons can release energy to the atomic cores, which can lead to lattice oscillations and additional heating of the material through heat accumulation.

The processing beam can preferably act on different spatial areas of the process zone. In this way, the greatest possible exposure to the process zone can be achieved, so that the temperatures occurring in the materials can be locally reduced in the individual foci of the processing beams, but the temperature required for melting the respective material is still generated in the process zone.

The processing beam can preferably impact different spatial areas of the process zone sequentially and / or randomly and / or chaotically. In other words, the foci of the processing beam move through the process zone in such a way that different spatial areas of the process zone are acted upon by one or more processing beams over time. In this way, too high energies can be avoided in a single location, so that the accumulation of voltages can be reduced.

Preferably, a processing beam emanating from a beam source can be moved by means of an acousto-optical deflector and / or divided into at least two separate processing partial beams. By using an acousto-optic deflector, the processing beam can be divided and deflected with high dynamics and any sequence, so that excessive energies can be avoided in a single location, so that the accumulation of voltages is reduced can.

Particularly preferably, the acousto-optic deflector can be acted upon by a sequentially and / or randomly and / or chaotically varying sound wave. In this way, the different spatial areas in the process zone can be acted upon in such a way that excessive energies can be avoided at a single location, so that the accumulation of voltages can be reduced.

Particularly preferably, two acousto-optical deflectors rotated by 90 ° relative to one another can be provided, by means of which the processing beam is deflected in a plane perpendicular to the processing beam. This allows the processing beams to be introduced into the process zone in a spatially very flexible manner.

The processing beam can preferably be shaped by means of a beam shaper before it acts on the different spatial areas. This enables an advantageous beam shape to be achieved by means of which the accumulation of stresses in the material of the workpieces can be reduced

A highly dynamic movement of the processing beam is understood here, inter alia, as one in which the processing beam is moved between the respective spatial areas of the process zone at a frequency of at least 100 kHz. In other words, the processing beam acts on the different spatial areas of the process zone at the stated frequency. The movement of the machining beam preferably takes place at a frequency of 100 kHz up to 10 MHz.

In an alternative view, a highly dynamic movement of the processing beam is understood to mean, among other things, one in which the movement from one spatial area of the process zone exposed to the processing beam to another spatial area of the process zone exposed to the processing beam takes a maximum of 10 μs. The movement of the processing beam preferably lasts between 10 μs and 0.1 μs from one spatial area to another spatial area of the process zone.

In a further alternative consideration, a highly dynamic movement of the processing beam is particularly advantageously understood here to mean, inter alia, one in which the movement from one spatial area of the process zone acted upon by the machining beam to another spatial area of the process zone acted upon by the machining beam is made possible, that initially at least one laser pulse, preferably a predetermined pulse train and / or all laser pulses of a burst, in one area the process zone is / are introduced into the material of the workpiece, then the processing beam is moved highly dynamically into the next spatial area of the process zone and then another laser pulse, preferably a predetermined further pulse train and / or all laser pulses of a further burst in this spatial area of the process zone is introduced into the material of the workpiece.

In other words, through the highly dynamic movement of the processing beam, laser pulses, preferably the laser pulses of a predetermined pulse train and / or all laser pulses from bursts, can be introduced one after the other in a defined manner into the different spatial areas of the process zone.

The movement of the processing beam is thus preferably interrupted until the laser pulse, preferably the predetermined pulse train and / or the laser pulses of a burst have been introduced into the spatial area of the process zone and is only then moved to the next spatial area of the process zone.

In this alternative consideration, the highly dynamic movement of the processing beam is preferably synchronized with the provision of the laser pulses and / or pulse trains and / or bursts, so that the highly dynamic movement of the processing beam only takes place in the pauses between the laser pulses and / or pulse trains and / or bursts.

In this way, the advantageous effects already described above can be achieved, which lead to an improvement in the quality of the machined workpiece and / or the joining process of two or more workpieces with one another.

The frequency of the movement of the highly dynamic processing can also be higher and, for example, above 10 MHz.

The highly dynamic movement of the processing beam between the different spatial areas for processing can be achieved, for example, by means of an acousto-optical deflector (AOD), preferably by means of two AODs arranged at an angle, preferably perpendicular to one another, and perpendicular to the beam direction, so that rapid movement of the machining beam can be achieved. By using two AODs arranged at an angle or preferably perpendicular to one another, a deflection can be achieved in the (two-dimensional) plane perpendicular to the processing beam, so that the highly dynamic movement of the processing beam takes place over the surface or through the volume of the workpiece or workpieces can. If only one AOD is used, movement along a (one-dimensional) line can be achieved.

In an alternative embodiment, a movement of the laser beam in one spatial direction can be achieved by means of an AOD and beam shaping or beam splitting can be achieved by means of a second AOD.

In a further alternative embodiment, a first AOD and a second AOD can be used to achieve a beam deflection in two spatial directions and one or two further AODs to achieve a beam splitting in one or two directions.

The movement of the processing beam and / or its shaping can also be achieved by means of an SLM (spatial light modulator) or diffractive optics.

By means of the highly dynamic movement of the processing beam, the individual spatial areas can be exposed to the processing beam in a predetermined sequence. In other words, a predetermined pattern of spatial areas can be traversed with the machining beam in a highly dynamic manner. The spatial areas can also be scanned in a highly dynamic manner with a chaotic or random pattern.

The individual spatial areas of the process zone can be arranged offset from one another by 1–10 µm, for example. In other words, after each laser pulse or each laser pulse train or each burst, the processing beam can be offset from one another by 1 - 10 µm within the process zone, in order to then apply the next laser pulse or the next laser pulse train or the next burst.

The workpieces can be processed, for example, in the form of joining, in particular welding, the workpieces to one another. By introducing the machining beam into the process zone, the material of the work piece (s) is / are melted and a weld seam is formed accordingly after the material has solidified again.

The proposed method can also be used to introduce further modifications to the surface of the material of the workpiece or of the workpieces.

A method for welding at least two workpieces is preferably proposed, with at least one of the workpieces transparent for a machining beam, preferably for a pulsed laser beam, particularly preferably for an ultra-short pulse laser beam, a weld seam being formed in the workpieces in a process zone acted upon by the machining beam.

Because the processing beam acts on different spatial areas of the process zone, it is possible to provide a distribution of the intensity of the introduced laser energy within the process zone in such a way that the stresses induced by the processing beam in the material of the workpieces can be reduced or at least redistributed to such an extent that a Improvement in the quality of the joined workpieces can be achieved and a large process zone can form.

In this way, several absorption areas can be addressed in the process zone by means of the processing beam, so that a more targeted initiation or guidance of the temperature induced by the processing beam and thus the respective melted areas can be achieved.

In conventional joining methods, a weld seam is made linearly and continuously, so that along this modification introduced by laser-induced melting areas, the temperature-induced stresses also accumulate in the materials of the joint partners. According to the proposed method, the accumulation of the temperature-induced stresses can be reduced by the exposure of different spatial areas of the process zone by the machining beam moved into the different spatial areas, since the temperature input does not take place continuously, but is interrupted by the application of the different spatial areas.

In other words, the temperature required for melting the material in the process zone is not introduced into the material starting from a single focus, but rather in spatial areas within the process zone which are spatially separated from one another and which are nevertheless thermally coupled to one another to the extent that heat can accumulate in the material.

The highly dynamic deflection of the processing beam, which acts on different spatial areas of the process zone and accordingly leads to spatially separated absorption areas within the process zone, which nevertheless influence each other thermally, the accumulated stresses occurring in the material of the workpieces can be reduced or these spatially be distributed in such a way that their influence on the stability of the joint is reduced. In this way, the occurrence of stresses induced by the machining beam in the joining partners can be reduced and an increased strength of the joint can be achieved.

Furthermore, it is also possible to weld with higher energies compared to conventional methods, since the stresses in the material do not accumulate so much. In this way the throughput can also be increased.

By applying the highly dynamic processing beam to different spatial areas of the process zone, the laser-induced heat that is introduced into the material can be individually adapted to the materials of the joining partners and to the other process parameters such as the geometry of the weld seam to be produced.

The process zone acted upon by the machining beam and the workpieces can preferably be moved relative to one another to form the weld seam. Applying a relative movement of the process zone with respect to the workpiece during the welding process results in a weld seam extending in the direction of movement after the previously melted material has solidified.

The processing beam is preferably divided into at least two separate processing partial beams and at least two processing partial beams then each act on different spatial areas of the process zone.

The processing partial beams can, as described above for the (individual) processing beam, also be moved highly dynamically into different spatial areas of the process zone.

The application of the different spatial areas of the process zone can then take place in a correspondingly highly dynamic manner.

In other words, a highly dynamic movement of the at least two processing partial beams can take place, so that in each case at least two different spatial areas of the process zone are exposed to the processing partial beams at the same time and then, for example after the two spatial areas have been subjected to a laser pulse or a laser pulse train or a burst, the machining partial beams are moved in a highly dynamic manner and correspondingly at least two further spatial areas of the process zone are exposed to the partial processing beams.

The above-mentioned object is also achieved by a device with the features of the independent device claim. Advantageous further developments emerge from the related subclaims, the present description and the attached figures.

Accordingly, a device for machining at least one workpiece is proposed, a beam source for providing a machining beam, preferably a pulsed laser beam, particularly preferably an ultrashort pulse laser beam, and an optical system for applying the machining beam to at least one workpiece, the optical system being designed for this purpose and is set up to move the machining beam in a highly dynamic manner between at least two different spatial areas of the at least one workpiece to form a process zone.

The advantageous effects mentioned above for the method can be achieved by means of the proposed device.

The configurations described above with regard to the method can also be included in the device in their respective device-like form in order to achieve the advantages described for the method and to further develop the device.

Figure list

• 1 eine schematische Darstellung eines Ausschnitts einer Vorrichtung zur Bearbeitung eines Werkstücks in einem ersten Ausführungsbeispiel;
• 2 eine schematische Darstellung der Beaufschlagung unterschiedlicher räumlicher Bereiche einer Prozesszone mittels Laserpulsen;
• 3 eine schematische Darstellung eines Ausschnitts einer Vorrichtung zur Durchführung eines Verfahrens zum Verschweißen von zwei Werkstücken in einem weiteren Ausführungsbeispiel; und
• 4 eine schematische Darstellung eines Ausschnitts einer Vorrichtung zur Durchführung eines Verfahrens zum Verschweißen von zwei Werkstücken in einem weiteren Ausführungsbeispiel.

Preferred further embodiments of the invention are explained in more detail by the following description of the figures. Show:

• 1 a schematic representation of a section of a device for machining a workpiece in a first embodiment;
• 2 a schematic representation of the application of different spatial areas of a process zone by means of laser pulses;
• 3 a schematic representation of a section of a device for performing a method for welding two workpieces in a further embodiment; and
• 4th a schematic representation of a section of a device for performing a method for welding two workpieces in a further embodiment.

Detailed description of preferred exemplary embodiments

Preferred exemplary embodiments are described below with reference to the figures. Identical, similar or identically acting elements are provided with identical reference numerals in the different figures, and a repeated description of these elements is partially dispensed with in order to avoid redundancies.

In 1 is a schematic section of a device 1 for machining one workpiece, here for machining two workpieces 110 , 120 shown. The device 1 is used to carry out a method for machining the workpieces 110 , 120 The processing can be, for example, a modification of the surface of the workpiece or a lift-off process. The proposed method can also be used to make further modifications to the material of the workpiece or the material of the workpieces 110 , 120 be introduced.

Machining for welding at least two workpieces is preferred 110 , 120 intended.

A machining beam 2 is provided by a beam source not shown here, the beam source preferably being provided in the form of a pulsed laser, preferably an ultra-short pulsed laser.

• - Wellenlänge zwischen 200 nm und 5000 nm
• - Repetitionsrate zwischen 100 Hz und 50 MHz (optional Bursts wobei die Repetitionsrate der Pulse im Burst zwischen 1 MHz und 50GHz liegen kann)
• - Laserpulsdauer zwischen 10 fs und 50 ps
• - Fokussierung so, dass Fluenz in den jeweiligen räumlichen Bereichen >0.01 J/cm2 (Modifikationsschwelle im Volumen typischerweise zwischen 1-5 J/cmz)
• - Relativer Vorschub des/der Werkstücke zum Bearbeitungsstrahl zwischen 0.01 und 1000 mm/s

The parameters of the beam source and the downstream optics can be selected as follows, for example:

• - Wavelength between 200 nm and 5000 nm
• - Repetition rate between 100 Hz and 50 MHz (optional bursts where the repetition rate of the pulses in the burst can be between 1 MHz and 50 GHz)
• - Laser pulse duration between 10 fs and 50 ps
• - Focusing so that fluence in the respective spatial areas> 0.01 J / cm2 (modification threshold in the volume typically between 1-5 J / cm2)
• - Relative advance of the work piece (s) to the machining beam between 0.01 and 1000 mm / s

The from the corresponding beam source, not shown, for example in the form of the above pulsed laser outgoing machining beam 2 is in the device 1 for performing machining of the material of the workpiece 110 or the workpieces 110 , 120 in a first optical element 30th , which in the embodiment shown as a lens 30th is symbolized, processed so that an acousto-optical deflector following in the beam path 32 can be operated appropriately.

The first optical element 30th can accordingly provide a beam expansion, a collimation, a focusing, a spatial and / or temporal beam shaping etc. which is suitable for the processing beam 2 prepare so that the acousto-optic deflector 32 can be operated appropriately.

Under an acousto-optic deflector, which is located in the in 1 shown embodiment as an acousto-optic deflector combined from two individual acousto-optic deflectors 320, 322 32 is shown very schematically, an active optical element is understood in the present case, in which a deflection of an incoming processing beam can be achieved by the introduction of sound waves. An acousto-optic deflector is also known as an AOD.

An acousto-optic deflector can be provided, for example, in the form of a transparent crystal cuboid, for example in the form of quartz glass or another crystal, into which structure-borne sound is entered by means of an acoustic coupler, for example by means of a piezo crystal. Due to the density fluctuations formed in the transparent cuboid by the structure-borne sound, an optical grating is formed correspondingly, on which diffraction of the incident light takes place.

In other words, in the acousto-optic deflector 32 diffraction of the light takes place at the optical grating formed in the crystal by the sound waves generated by the density fluctuations.

The actual deflection of the incident light or the diffraction of the incident light of the processing beam emanating from the beam source is therefore dependent on the frequency of the acousto-optic deflector 32 introduced acoustic oscillation or of the wavelength of the acoustic wave and thus of the lattice constant formed in this way of the density fluctuations formed in the cuboid. By varying the introduced frequency of the introduced acoustic oscillation and thus the lattice constant, the actual deflection of the incident light beam of the processing beam can be varied accordingly.

About the amplitude of the in the acousto-optic deflector 32 In contrast, with the acoustic oscillation introduced, an intensity modulation can also be achieved in such a way that, with a stronger amplitude, the corresponding density fluctuations are more pronounced and thus the diffraction orders are more pronounced.

In other words, in the acousto-optic deflector 32 Both a variable angular deflection of the light beam and a variation of the intensity of the individual diffraction orders can be achieved through the input of sound energy.

According to the embodiment in 1 is the acousto-optic deflector 32 (or the combination of the two acousto-optic deflectors 320, 322) correspondingly after the first optical element 30th arranged. The one through the first optical element 30th processed machining beam 2 is thus by the acousto-optic deflector 32 or the two acousto-optic deflectors 320, 322 according to the respective settings and in particular the introduced frequency and the introduced amplitude.

One through an initial setting of the acousto-optic deflector 32 deflected machining beam 2 ' and one by another setting of the acousto-optic deflector 32 deflected machining beam 2 " are in the 1 shown schematically for the respective first diffraction order. Those in higher diffraction orders are not shown in the figure for the sake of simplicity.

The two deflected machining beams 2 ' , 2 " in the 1 symbolize two of the many through the acousto-optical detector 32 possible distractions, each one after the other in a spatial area 220 , 222 of the process zone 200 in the material of the workpieces 110 , 120 be introduced. By introducing other frequencies into the AOD (s) 32 Of course, other deflections can also be achieved, so that other spatial areas of the process zone 200 can be acted upon with the then deflected machining beam.

The movement of the deflected machining beams 2 ' , 2 " so that they are in the different spatial areas 220 , 230 the process zone 200 can be introduced in a highly dynamic manner. This can be done particularly well by means of the acousto-optical deflector 32 (or the two acousto-optic deflectors 320, 322 connected one after the other), since these components allow movement with particularly high Frequencies is made possible. A distinction must be made between the (excitation) frequency of the acoustic wave that is generated in the acousto-optical deflector 32 the grid formation takes over, and the frequency movement of the machining beam. The frequency of the movement of the machining beam corresponds to a frequency of the change in the excitation frequency, that is to say a frequency of switching from one excitation frequency to a subsequent excitation frequency.

With a highly dynamic movement of the processing beam, for example by means of one or more AODs 32 , 320, 322 is understood, among other things, as one in which the deflected processing beam is moved between the respective spatial areas of the process zone at a frequency of at least 100 kHz (the excitation frequency of an AOD changes accordingly with this frequency). The movement of the deflected machining beam preferably takes place at a frequency of 100 kHz up to 10 MHz. Via a corresponding control of the AOD (s) 32 , 320, 322 with the frequencies mentioned, a movement of the deflected processing beam can thus be achieved.

The movement of one with the deflected machining beam 2 ' acted spatial area 220 the process zone 200 to another with the deflected machining beam 2 " acted spatial area 230 the process zone 200 preferably lasts at most 10 μs. In other words, the change in the excitation frequency of the AOD takes time 32 The movement of the deflected machining beam lasts particularly preferably at most 10 μs 2 ' , 2 " between 10µs and 0.1µs from a spatial area 220 to another spatial area 230 the process zone 200 .

The Indian 1 shown acousto-optic deflector 32 is accordingly constructed in two parts and two acousto-optical deflectors 320, 322 arranged one after the other in the beam path are provided, which in the embodiment shown are rotated by 90 ° to each other in order to deflect the processing beam in this way 2 in the perpendicular to the machining beam 2 lying plane (i.e. an X / Y plane). Of course, the two acousto-optic deflectors can 32 can also be aligned at a different angle to one another - however, the alignment at 90 ° enables easier control, whereby the deflection can then take place according to the desired X / Y deflection.

The acousto-optical deflector made up of the individual AODs 320, 3220 32 deflected machining beams 2 ' , 2 " are made by means of a second optical element 34 , which is also shown schematically in the form of a lens in the embodiment shown, prepared for further processing. For example, the machining beams 2 ' , 2 " by means of the second optical element 34 collimated for propagation into the far field.

The second optical element 34 can correspondingly, for example, a collimation of the acousto-optic deflector 32 outgoing machining beams 2 ' , 2 " to reach.

In such an arrangement of two acousto-optic detectors, a half-wave plate is preferably provided between the two acousto-optic deflectors.

Because in the acousto-optic deflector 32 no complete decoupling of the incoming processing beam 2 exclusively into the processing beam separated by the respective diffraction angle of the first diffraction order 2 , ' 2 " , but also in the zeroth diffraction order, i.e. collinear to the processing beam arriving from the beam source 2 , there is also still a beam intensity, is an aperture to eliminate the zeroth diffraction order 36 intended. The aperture 36 can also serve to eliminate rays in higher diffraction orders in order to achieve a clean decoupling of only the first diffraction order.

In other words is through the aperture 36 a jet cleaning element introduced into the beam path, by means of which undesired components can be removed from the jet.

By means of one in the beam path after the second optical element 34 and the aperture 36 arranged third optical element 38 which is in the 1 is also shown in the form of a lens, the processing beams which are spaced apart from the zeroth diffraction order, that is to say which have a spatial offset, are then used 2 ' , 2 " refocused. In other words, is through the third optical element 38 a focusing of the machining beams provided with a local offset 2 " , 2 " into the material of the workpiece 110 , 120 or in those in the workpieces 110 , 120 horizontal process zone 200 reached.

By using the acousto-optic deflector 32 can accordingly move the machining beam very quickly 2 ' , 2 " can be achieved with the machining beam 2 ' , 2 " then accordingly in different spatial areas 220 , 230 the process zone 200 can be introduced.

In 2 shows in a very schematic diagram the exposure to different spatial areas 220 , 230 the process zone 200 with laser pulses 250 shown. Here are the laser pulses 250 very schematically summarized in the diagram to form separate bursts 252 . The bursts 252 each last a period of time TB .

In the 2 becomes one burst at a time 252 to another spatial area 220 , 230 , 240 the process zone 200 brought in. The individual bursts 252 are moved to the different spatial areas one after the other 220 , 230 , 240 brought in.

In the breaks TP between bursts 252 the processing beam is activated by a corresponding control of an AOD 32 diverted so that successive bursts 252 in different spatial areas 220 , 230 , 240 be introduced into the workpiece.

The bursts are preferred 252 of the machining beam 2 and the control of the AODs is synchronized with one another in such a way that a change in the excitation frequency of the AODs in the respective pulse pauses TP between bursts 252 takes place. Accordingly, the new excitation frequency for the AODs is first set and only then is a laser pulse or a burst or a pulse train sent through the AODs.

In other words, due to the highly dynamic movement of the machining beam, laser pulses, preferably the laser pulses of a predetermined pulse train and / or all laser pulses of bursts, can be successively entered into the different spatial areas 220 , 230 , 240 the process zone 200 be introduced in a defined manner.

The movement of the machining beam is thus preferably interrupted until the laser pulse, preferably the predetermined pulse train and / or the laser pulses of a burst, enter the spatial area 220 the forming process zone 200 and only then becomes the next spatial area 230 the process zone 200 emotional.

In 3 is a schematic section of a device 1 for carrying out a method for welding two workpieces, also shown schematically 110 , 120 by means of a machining beam 2 shown.

With the workpieces 110 , 120 it can be transparent workpieces, with at least the workpiece lying on top in the beam direction 110 Must be transparent to the machining beam when at an interface 100 between the upper workpiece 110 and the lower workpiece 120 a welding is to be carried out.

The actual welding is here schematically in the form of a weld seam 210 shown, which in the embodiment shown has a substantially linear and continuous extension. But there are also differently shaped weld seams for joining the workpieces 110 , 120 conceivable, for example in a curved or curved shape or through the formation of individual segments or weld points.

In this context, a transparent workpiece is understood to be one which is intended for the machining beam 2 is transparent. In other words, the machining beam can 2 pass through a transparent workpiece without significant weakening or scattering.

The position of one between the workpieces 110 , 120 by means of the machining beam 2 generated weld seam 210 as well as the structure of the device 1 or 3 for carrying out the method for welding the workpieces 220 , 230 is related to the 4th shown again in detail.

In 3 is schematically a machining beam 2 shown, which emanates from a beam source not shown in the figure and which can be provided in the form of a pulsed laser beam. An ultrashort pulse laser for providing the machining beam can be particularly preferred 2 be used.

For example, a pulsed laser beam with wavelengths of 1030 nm or 1064 nm or 515 nm or 532 nm with pulses in the femtosecond range or picosecond range and with frequencies of the repetition rate of 100 kHz up to several MHz can be used. The laser for generating the pulsed laser beam can also be operated in burst mode.

The processing beam emanating from the beam source, not shown here, for example in the form of the said laser 2 is in the device 1 for performing the welding in a first optical element 30th , which in the embodiment shown as a lens 30th is symbolized, processed so that an acousto-optical deflector following in the beam path 32 can be operated appropriately. The first optical element 30th can accordingly provide a beam expansion, a collimation, a focusing, a beam shaping in the time domain, etc., which is suitable for the processing beam 2 prepare so that the acousto-optic deflector 32 can be operated appropriately.

Under an acousto-optic deflector, which in the exemplary embodiment has the reference number 32 is shown very schematically, an active optical element is understood in the present case, in which a deflection of an incoming processing beam can be achieved by the introduction of sound waves. An acousto-optic deflector is also known as an AOD.

An acousto-optic deflector can be provided, for example, in the form of a transparent crystal cuboid, for example in the form of quartz glass or another crystal, into which structure-borne sound is entered by means of an acoustic coupler, for example by means of a piezo crystal. Due to the density fluctuations formed in the transparent cuboid by the structure-borne sound, an optical grating is formed correspondingly, on which diffraction of the incident light takes place.

In other words, in the acousto-optic deflector 32 a diffraction of the light take place at the optical grating formed in the crystal by the sound waves generated by the density fluctuations.

The actual deflection of the incident light or the diffraction of the incident light of the processing beam emanating from the beam source is therefore dependent on the frequency of the acousto-optic deflector 32 introduced acoustic oscillation or of the wavelength of the acoustic wave and thus of the lattice constant formed in this way of the density fluctuations formed in the cuboid. By varying the introduced frequency of the introduced acoustic oscillation and thus the lattice constant, the actual deflection of the incident light beam of the processing beam can be varied accordingly.

About the amplitude of the in the acousto-optic deflector 32 In contrast, with the acoustic oscillation introduced, an intensity modulation can also be achieved in such a way that, with a stronger amplitude, the corresponding density fluctuations are more pronounced and thus the diffraction orders are more pronounced.

In other words, in the acousto-optic deflector 32 Both a variable angular deflection of the light beam and a variation of the intensity of the individual diffraction orders can be achieved through the input of sound energy.

According to the embodiment in 3 is the acousto-optic deflector 32 correspondingly after the first optical element 30th arranged. The one through the first optical element 30th processed machining beam 2 becomes thus of the acousto-optic deflector 32 in processing partial beams that are in the 3 schematically in the form of the processing partial beams 20th , 22nd of the first order of diffraction are shown split and deflected. Those in higher diffraction orders are not shown.

The by means of the acousto-optic deflector 32 deflected processing partial beams 20th , 22nd are made by means of a second optical element 34 , which is also shown schematically in the form of a lens in the embodiment shown, prepared for further processing. For example, the processing partial beams 20th , 22nd by means of the second optical element 34 collimated for propagation into the far field.

The second optical element 34 can correspondingly, for example, a collimation of the acousto-optic deflector 32 outgoing machining partial beams 20th , 22nd to reach.

Instead of the 3 shown an acousto-optic deflector 32 It is also possible to provide two acousto-optical deflectors arranged one after the other in the beam path, which are rotated by 90 ° to one another, for example, in order in this way to deflect perpendicular to the processing beam 2 to reach lying plane. Of course, the two acousto-optic deflectors can 32 can also be aligned at a different angle to one another - however, the alignment at 90 ° enables easier control.

In such an arrangement of two acousto-optic detectors, a half-wave plate is preferably provided between the two acousto-optic deflectors.

Because in the acousto-optic deflector 32 no complete decoupling of the incoming processing beam 2 exclusively into the partial beams separated by the respective diffraction angle of the first diffraction order 20th , 22nd takes place, but also in the zeroth diffraction order, that is, collinear to the processing beam arriving from the beam source 2 , there is also still a beam intensity, is an aperture to eliminate the zeroth diffraction order 36 intended. The aperture 36 can also serve to eliminate partial beams in higher diffraction orders in order to achieve a clean coupling out of only the first diffraction order.

By means of one in the beam path after the second optical element 34 and the aperture 36 arranged third optical element 38 which is in the 3 is also shown in the form of a lens, then the one spacing of the zeroth order of diffraction having, that is, processing partial beams having a spatial offset 20th , 22nd refocused. In other words, is through the third optical element 38 a focusing of the partial processing beams provided with a local offset 20th , 22nd reached.

The machining partial beams 20th , 22nd are on a beamformer 40 focused, which is provided, for example, in the form of a phase-sensitive element, for example a spatial light modulator (SLM) which is also referred to as a spatial modulator for light. The spatial structure of short laser pulses can be shaped via such an SLM. In particular, it can be used to form laser pulses in Bessel form or in the form of several Gaussian spots.

The beamformer 40 can also be another active optical element in order to shape the processing beam.

By means of the beam shaper 40 can the processing partial beams 20th , 22nd are shaped in their beam structure so that they have a predetermined spatial structure, for example. By means of the beam shaper 40 The patterns or structures for the application of the processing beam to the different spatial areas of the process zone can also be used 2 or the machining partial beams 20th , 22nd can be specified.

By means of the beam shaper 40 can the processing partial beams 20th , 22nd can also be divided into further processing partial beams, not shown in the schematic exemplary embodiment, or from each of the processing partial beams 20th , 22nd predetermined patterns or patterns can be generated.

After the beamformer 40 kick through the beamformer 40 appropriately shaped processing partial beams then through a further optical element 42 through that in the in 3 The embodiment shown is again shown in the form of a lens. By means of the further optical element 42 finds a focusing of each of the individual processing beams, which either only through the acousto-optical deflector 32 or additionally by the beam shaper 40 were divided into the forming process zone 200 instead of.

The individual optical elements 30th to 38 , 40 and 42 can in a common optical system 400 be organized. Except for the acousto-optic deflector 32 all other optical elements are optional.

The forming process zone 200 lies at least partially in one or in both of the workpieces 110 , 120 . By focusing the partial machining beams with a local offset 20th , 22nd into the process zone 200 by means of the further optical element 42 accordingly, the partial processing beams are also focused 20th , 22nd in different spatial areas 220 , 230 the process zone 200 instead of. In other words, it becomes one of the machining partial beams 20th in a first spatial area 220 the process zone 200 focused, while another of the processing partial beams 22nd in a second spatial area 230 the process zone 200 is focused.

That from the first processing sub-beam 20th acted spatial area 220 is at a distance from that of the second processing partial beam 22nd acted spatial area 230 because the machining partial beams 20th , 22nd also have a spatial offset to one another. The two of the machining partial beams 20th , 22nd exposed areas 220 , 230 but are preferably only spaced so far apart that there is a thermal coupling of the two areas 220 , 230 present. This can be achieved in the process zone 200 present material of one or both of the workpieces 110 , 120 by the input of the laser energy through the partial processing beams 20th , 22nd despite the spatial distance between the two areas 220 , 230 is melted.

The device 3 accordingly comprises the optical system 400 through which the pulsed machining beam 2 then in the form of the machining partial beams 20th , 22nd on the workpieces 110 , 120 hits. The machining partial beams 20th , 22nd are in the spatial areas 220 , 230 in one in one or both workpieces 110 , 120 lying process zone 200 focused, reducing the intensity of the machining partial beams 20th , 22nd in the in the process zone 200 lying foci is highest in each case, but lower in the respective surrounding areas. Material processing in the process zone 200 takes place because of the high intensity of the processing partial beams 20th , 22nd their respective foci lead to a melting of the in the process zone 200 present material comes. As a result, during the subsequent cooling process, two welds together beforehand in the process zone 200 material areas that are present separately and are now cohesively connected to one another by the melting can be achieved.

When using a pulsed machining beam 2 , especially when using an ultrashort pulse laser, are due to the very high intensities that can be achieved in the through the optical system 400 provided foci in the glass material of the at least one workpiece 110 , 120 nonlinear absorption effects achieved. When using suitable repetition rates of the pulsed machining beam 2 heat accumulation effects occur in the glass material, which leads to a local melting of the glass material in the process zone 200 comes.

The process is based on the knowledge that when welding workpieces 110 , 120 made of glass by means of a pulsed machining beam 2 , for example a pulsed laser beam, preferably an ultrashort pulse laser, by means of which high intensities that can be achieved in the respective beam focus, non-linear absorption effects can be achieved in the glass. If corresponding repetition rates are used for the pulsed machining beam, the amount accumulates in the process zone by means of the respective pulses 200 energy introduced, so that there is a local melting of the glass material due to corresponding heat accumulation effects. This creates in the vicinity of the respective geometric focus of the pulsed processing partial beams 20th , 22nd a highly absorbing plasma initially the size of the focus volume.

To connect the workpieces 110 and 120 to reach the process zone that is being formed 200 accordingly in the workpieces 110 , 120 placed that they are close to the interface 100 is arranged or the interface 100 includes. This is done by means of the appropriately designed and configured optical system 400 the machining partial beams 20th , 22nd processed accordingly and into the process zone that is being formed 200 focused into it.

In the process zone 200 Then the melting of the material of one, several or all workpieces takes place 110 , 120 instead of welding the workpieces after the previously melted material has solidified again 110 , 120 through the melted and then solidified material.

The positioning of the individual spatial areas 220 , 230 in the process zone 200 can be varied in that different deflections of the processing partial beams 20th , 22nd in the acousto-optic deflector 32 can be achieved in that in the acousto-optic deflector 32 varying sound waves are coupled. Both the frequencies and the intensities of the acousto-optical deflector can be used 32 coupled sound waves can be varied.

Through a corresponding sequence of in the acousto-optic deflector 32 Coupled frequencies can then be a corresponding sequence of deflections of the processing partial beams 20th , 22nd can be achieved, which in turn in a sequence of different local offsets of the processing partial beams, which in turn in a sequence of exposure to different spatial areas 220 , 230 the process zone 200 results.

This can be used to control the in the acousto-optical deflector 32 coupled sound waves are reached that the process zone 200 in a sequence of different spaced apart areas 220 , 230 with the processing partial beams 20th , 22nd is applied.

In other words, the volume of the process zone 200 by means of the acousto-optic deflector 32 be scanned.

The sequence of going into the acousto-optic deflector 32 Different frequencies coupled in can consist of a fixed sequence and / or be chaotic and / or random within predetermined limits.

In other words, the acousto-optic deflector functions 32 in the exemplary embodiment shown, like a scanner, by means of which a division of the processing beam originally emanating from the beam source 2 in two processing partial beams 20th , 22nd is made possible, which are processed accordingly in their beam shape via the subsequent optics and then in by means of the acousto-optical deflector 32 certain spatial areas 220 , 230 the process zone 200 hit. By varying the deflection of the partial beams 20th , 22nd in the acousto-optic deflector 32 can also change the position of the spatial areas 220 , 230 in the process zone 200 can be varied.

By appropriately designing the acousto-optical deflector 32 and the subsequent optics, especially the shape of the aperture 36 and the shape of the beam shaper 40 can furthermore be achieved that by means of the acousto-optic deflector 32 the different spatial areas 220 , 230 the process zone 200 one after the other or sequentially or simultaneously.

The high dynamics of the acousto-optic deflector 32 furthermore enables the respective deflection of the partial beams to be switched quickly 20th , 22nd such that the spatial areas 220 , 230 the process zone 200 can be moved quickly or different patterns or patterns can be followed one after the other.

Control of the acousto-optical deflector can be designed sequentially or chaotically or randomly or in some other way 32 lead to the fact that there is a sufficient amount of energy in the process zone that is being formed 200 is entered in order to melt the work piece or pieces 110 , 120 To achieve the necessary temperatures, which lead to a melting of the material, for example at an interface between the workpieces 110 , 120 leads. At the same time, however, the continuous and uninterrupted occurrence of high local temperatures over a period of time that is too long is avoided, so that temperature-induced stresses are introduced into the workpieces 110 , 120 and especially in to the process zone 200 or areas of the workpieces adjacent to the melting area 110 , 120 is reduced.

The on the work pieces 110 , 120 incident processing partial beams 20th , 22nd are in the direction of displacement X relative to the workpieces 110 , 120 slidable to in the work pieces 110 , 120 a linear or curved shaped weld 210 to move in. Either the workpieces can be used to form the shift 110 , 120 or the machining partial beams 20th , 22nd or both in opposite directions along the direction of displacement X be moved. There can be other movements parallel to that through the interface 100 trained level can be carried out to suitably more complex shapes of welds 210 to move in. Through the movement of the processing partial beams 20th , 22nd relative to the workpieces 110 , 120 can reduce the expansion of the weld 210 in the direction of movement X to be determined.

Since the one with the acousto-optic deflector 32 achievable scanning speeds are very high, the necessary energy can be entered into the material through a targeted entry of the laser energy and correspondingly targeted entry of the respective laser pulses, which can achieve reliable melting and thus a reliable connection of the workpieces with one another, but at the same time due to the distributed input of the energy and the avoidance of a consistently linear introduction of the laser energy along the desired weld seam 210 the avoidance of tension can be achieved.

Because the processing beam originally originating from the beam source 2 in at least two processing partial beams 20th , 22nd divided and the application of the processing beam in different spatial areas 220 , 230 the process zone 200 takes place, and in particular a dynamic loading of the different spatial areas 220 , 230 takes place, it can be avoided that the weld seam 210 introduces increased stresses into the joint partners through the introduction of a continuous, constant and uniform heating zone, as occurs when a continuous beam with a laser beam is introduced in conventional welding processes. Rather, in the proposed method, the local heating is repeatedly interrupted and moved to a different spatial area 220 , 230 within the process zone 200 shifted so that the heat input at a single spot, which is with the focus of the processing partial beam 20th , 22nd coincides, is interrupted and accordingly is also not continuously introduced at the one spot.

In other words, it becomes the process zone 200 in different spatial areas 220 , 230 which change sequentially and / or chaotically and / or randomly over the course of time and along the weld seam to be achieved, but are nevertheless supplied with the necessary energy to generate the weld seam.

The distance between the different spatial areas 220 , 230 the process zone 200 is usually chosen so that there is a thermal coupling between the different spatial areas 220 , 230 present. This can be achieved in the process zone 200 those for joining the workpieces 110 , 120 required melt is formed, a high local energy input along a single, continuous, continuous weld line is avoided.

In 4th is the device and the method for machining two workpieces 110 , 120 shown again in a second detailing.

In the embodiment shown, the workpieces are 110 , 120 made of glass, for example in the form of two glass panes - those on a common and between the two workpieces 110 , 120 arranged interface 100 are arranged next to each other and at a portion of the interface 100 are welded together. In other words, at least part of the bottom is located 114 of the 3 shown upper workpiece 110 at the top 122 of the lower workpiece 120 at. The top 122 of the lower workpiece 120 and the bottom 114 of the upper workpiece 110 accordingly together form the interface 100 in which the welding is to be made or was made.

The two workpieces 110 and 120 can in the area of the formation of the interface 100 be pressed against each other in order to position and fix the two workpieces beforehand 110 and 120 to achieve against each other.

Due to the nature of their material, namely glass, the two workpieces 110 , 120 essentially transparent to the pulsed machining beam 2 or the processing partial beams 20th , 22nd with which the welding of the two workpieces 110 , 120 should be carried out. This allows the pulsed processing partial beams 20th , 22nd , which are provided for performing the welding, through the workpieces 110 and 120 pass through and especially through the upper workpiece 110 through to the interface 100 get there. This means that the workpieces are welded together 110 and 120 within the by the two workpieces 110 , 120 jointly formed workpiece volume possible.

Such a welding within a workpiece volume formed by at least two workpieces is not possible in the case of materials that are opaque to a machining beam.

The lower workpiece 120 but can also be used for the machining beam 2 or the processing partial beams 20th , 22nd be made opaque. The machining partial beams 20th , 22nd but can still through the upper, for the processing partial beams 20th , 22nd transparent, workpiece 110 of glass through to the one between the two workpieces 110 , 120 lying interface 100 arrive to make a weld there.

The structure of the optical system 400 otherwise corresponds to the 3 described.

As far as applicable, all the individual features that are shown in the exemplary embodiments can be combined with one another and / or exchanged without departing from the scope of the invention.

List of reference symbols

1

Device for welding workpieces

100

Interface

110

(upper) workpiece

112

upper surface of the upper workpiece

114

lower surface of the upper workpiece

120

(lower) workpiece

122

upper surface of the lower workpiece

124

lower surface of the lower workpiece

2

Machining beam

2 '

deflected machining beam

2 "

deflected machining beam

20th

Machining partial beam

22nd

Machining partial beam

200

Process zone

210

Weld

220

spatial area of the process zone

230

spatial area of the process zone

240

spatial area of the process zone

250

Laser pulses

252

Burst

30th

first optical element (lens)

32

acousto-optic deflector

34

second optical element (lens)

36

cover

38

third optical element (lens)

40

Beam shaper

42

further optical element (lens)

400

optical system

X

Direction of movement

TP

Break

TB

Burst

Claims (15)

Method for processing at least one workpiece (110, 120), the workpiece (110, 120) being acted upon by a processing beam (2), preferably a pulsed laser beam, particularly preferably an ultrashort pulse laser beam, the processing beam (2, 2 ', 2 ", 20, 22) is moved highly dynamically between at least two different spatial areas (220, 230) to form a process zone (200). Procedure according to Claim 1 , characterized in that the processing beam (2) is moved between the two spatial areas (220, 230) at a frequency of 100kHz to 10MHz and / or that the processing beam is moved within 10µs to 0.1µs between the two spatial areas (220, 230) is moved. Procedure according to Claim 1 or 2 , characterized in that the processing beam (2) is moved by means of an acousto-optical element (32, 320, 322), preferably by means of two acousto-optical elements which are oriented at an angle to one another. Procedure according to Claim 3 , characterized in that the acousto-optical element (32) with a sequential and / or random and / or chaotically varying sound wave is applied. Method according to one of the preceding claims, characterized in that the machining beam (2) is a pulsed laser beam and the movement between the two spatial areas (220, 230) is carried out in the pulse pauses (TP). Method according to one of the preceding claims, characterized in that at least two workpieces (110, 120) are provided, at least one of the workpieces (110, 120) being transparent to the machining beam (2), and in the workpieces (110, 120) a weld seam (210) is formed in the process zone (200), the machining beam (2) being split in a highly dynamic manner into at least two separate machining partial beams (20, 22) and at least two machining partial beams (20, 22) each having different spatial areas (220, 230) ) act on the process zone (200) and / or the machining beam (2) is moved highly dynamically and at least two deflected machining beams (2 ', 2 ") act on different spatial areas (220, 230) of the process zone (200). Procedure according to Claim 6 , characterized in that each of the processing beams (2 ', 2 ", 20, 22) acts on a different spatial area (220, 230) of the process zone (200). Method according to one of the preceding claims, characterized in that two acousto-optical deflectors rotated by 90 ° against each other are provided, by means of which a deflection of the processing beams (2 ', 2 ", 20, 22) in a direction perpendicular to the processing beam (2) Level is carried out. Method according to one of the preceding claims, characterized in that the processing beam (2, 2 ', 2 ", 20, 22) strikes different spatial areas (220, 230) of the process zone (200) sequentially and / or randomly and / or chaotically . Method according to one of the preceding claims, characterized in that the processing beams (2 ', 2 ", 20, 22) are each shaped by means of a beam shaper (40) before they act on the different spatial areas (220, 230). Method according to one of the preceding claims, characterized in that the forming process zone (200) acted upon by the partial machining beams (20, 22) and the workpieces (110, 120) are moved relative to one another. Device (1) for processing at least one workpiece (110, 120), wherein a beam source for providing a processing beam (2), preferably a pulsed laser beam, particularly preferably an ultrashort pulse laser beam, and an optical system (400) for impinging on at least one workpiece (110,120 ) are provided with the processing beam (2), the optical system (400) being designed and set up to move the processing beam (2) in a highly dynamic manner between at least two different spatial areas (220, 230) to form a process zone (200). Device (1) according to Claim 12 , characterized in that at least two workpieces (110, 120) can be welded with it, at least one of the workpieces (110, 120) being transparent to the machining beam (2), the optical system (400) being designed and set up to Split the machining beam (2) into at least two separate machining partial beams (20, 22) and apply at least two machining partial beams (20, 22) to different spatial areas (220, 230) of the process zone (200). Device (1) according to Claim 12 or 13 , characterized in that the optical system (400) has an acousto-optical deflector (32) for the highly dynamic movement of the machining beam (2). Device (1) according to Claim 14 , characterized in that the optical system (400) has two acousto-optical deflectors, by means of which a deflection of the processing partial beams (20, 22) is made possible in a plane perpendicular to the processing beam (2).

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