DE102020102077B4 - Laser processing device and method for laser processing a workpiece - Google Patents

Abstract

Laser processing device for processing predetermined processing points (1) of a workpiece (2), comprisinga. a laser radiation source (3) which is set up to generate a laser beam (L) and to emit it along an optical path (4) in the direction of the workpiece (2);b. a beam splitting unit (5) which is arranged downstream of the laser radiation source (3) in the beam direction and is set up to split the laser beam (L) into a bundle of partial beams (T); c. an optical control unit downstream of the beam splitting unit (5) in the beam direction, comprising a reflective optical functional unit (8) formed from an array (14) of reflective microscanners (15), wherein the optical control unit is set up to • from the bundle of partial beams (T ) to select any number of partial beams in any spatial combination and to direct them onto the workpiece (2),• at least one, preferably each, of the partial beams (T) directed onto the workpiece (2) using a partial beam (T ) to position and/or move the associated microscanners (15) of the array (14) of microscanners (15) within a predetermined partial beam scanning area (ST) of the respective partial beam (T), characterized in that the laser processing device has an optical functional unit (7) comprises, which is arranged between the beam splitting unit (5) and the reflective optical functional unit (8), where in which the optical functional unit (7) comprises a lens array (11) of lenses (12), the partial beams (T) belonging to the bundle of partial beams (T) traveling on a first beam path until they are reflected at the reflective optical functional unit (8) through the pass through the lens array (11), and after being reflected at the reflective optical functional unit (8), at least some of the partial beams (T) reflected there again pass through the lens array (11) on a second beam path, namely in such a way that a respective partial beam (T ) on the second beam path through a lens (12) of the lens array (11) which is arranged adjacent to a lens (12) of the lens array (11) through which the partial beam (T) passes on the first beam path.

Description

The present invention relates to a laser processing device and a method for laser processing a workpiece at predetermined processing points using the laser processing device according to the invention.

The processing points mentioned can be, for example, defects in a workpiece which are subjected to a repair or correction carried out by means of laser processing. In this context, the workpieces mentioned can be displays or display surfaces, for example. Furthermore, the laser processing device proposed with the invention or the method proposed with the invention for processing a workpiece by way of a "laser induced forward transfer" (abbreviated: LIFT) process can be used, i.e. for processing predetermined processing points of a workpiece. A further field of application of the invention is the laser drilling of printed circuit boards for the production of plated through holes (via holes, blind VIA holes or through VIA holes). The workpiece is provided with holes at various points.

The advantages associated with laser drilling compared to other drilling methods are in particular that the drilling process can be carried out without contact and wear, with high precision and at high speed. Furthermore, even the smallest diameters and high aspect ratios are accessible. For example, bore diameters of up to 20 μm can be formed. Furthermore, the bores formed by laser drilling generally have sharp edges and freedom from material at the borehole entry and exit.

In the case of laser drilling, percussion drilling and trepanning are used in particular. The number of laser pulses required to form the bore increases in the order mentioned. With percussion drilling, the hole is formed by applying a series of consecutive individual pulses to the area to be processed. One speaks of trepanning when the laser beam is guided along a circular contour over the workpiece surface and the hole is cut out by the pulsed laser beam. The procedure thus corresponds to percussion drilling with subsequent circular cutting. The present invention can relate to all of the variants of laser drilling described above.

As already mentioned, the present invention can be used in particular to form laser bores in a workpiece. As already mentioned, the laser drilling process is particularly suitable for the formation of vias (so-called VIA holes) between the conductor track levels of a printed circuit board. Printed circuit boards are often multi-layered and comprise an upper and lower electrically conductive metal layer enclosing an electrically insulating intermediate layer made of plastic, ceramic or a composite material (e.g. FR4, which comprises an epoxy resin and glass fiber fabric). By using laser radiation, a hole can be formed in a predetermined processing area of the printed circuit board, i.e. both the metal layers and the insulating intermediate layer can be removed by means of laser drilling. The VIA hole can protrude completely through the workpiece (so-called through VIA holes), but a VIA hole can also be formed in such a way that only one of the metal layers and the intermediate layer in the area of the hole is removed (so-called blind VIA holes) . It should be expressly emphasized at this point that the invention can be provided for forming both through via holes and blind via holes. Laser drilling is suitable for processing printed circuit boards with a thickness of one to several millimeters, but laser drilling can also be carried out on thin printed circuit boards with a thickness of a few micrometers, for example 50 - 60 µm. Holes can also be formed on flexible foils by means of laser processing. The film thickness can vary from a few micrometers to the millimeter range, but this does not stand in the way of processing such a film with the device according to the invention or the method according to the invention. Otherwise, printed circuit boards can also be designed as foils. The latter can also be processed with the device and the method according to the invention.

However, other applications are not excluded, in which the laser processing device proposed with the invention or the method proposed with the invention is used.

A possible field of application of the laser processing device proposed according to the invention or the method proposed according to the invention relates to the production of graphic displays such as displays, OLED (organic light emitting diode) displays or mini LED displays are mentioned here by way of example. Production-related defects may occur during production. Such defects are in To be understood within the framework of the terminology used here as "processing points". These imperfections can occur in certain pixels of the display, for example in the electrical contacts. Undesirable deviations with regard to the surface structure (e.g. homogeneity, layer thickness, planarity, etc.) can be present in those imperfection areas.

Since such imperfections are usually not distributed homogeneously on the display surface and often occur on a large number of display pixels, it is desirable to subject the imperfections to a repair or correction process that, on the one hand, allows multiple imperfections to be processed at the same time and, on the other hand, is flexible can be adapted to a defect distribution present on a specific display. Laser processing techniques are particularly suitable for such correction of defects, because such techniques ensure pixel-by-pixel, high-resolution and, as it were, fast (removing) processing. Machining defects of this type with individual laser beams is generally known from the prior art, but is associated with disadvantages in terms of the method and the duration of the method. Accordingly, processes that allow parallel processing of several defects are of particular interest. From the U.S. 9,592,570 B2 parallel processing provided via beam selection is known, but only that individual spot rows or columns can be selected.

It should be expressly emphasized at this point that the present invention is not only suitable for processing or repairing defects in a display Allow removing (ablating) processing. At the same time, the present invention--as mentioned at the outset--is suitable for forming laser bores at predetermined or desired processing points on a workpiece, e.g. a printed circuit board. The processed material must therefore be able to be ablated by laser radiation. Furthermore, the present invention is suitable for use in the LIFT method already mentioned above. Pulsed laser beams (e.g. in point-and-shoot mode) are directed onto a coated substrate in order to transfer material to a second substrate in the direction of the laser radiation. LIFT processes can be used for the production of thermoelectric transfer materials, polymers and for printing on substrates. Accordingly, within the scope of the invention, the “processing points” can also be understood to mean those points on a first substrate (a workpiece within the meaning of the invention) at which a material transfer by way of the LIFT method to a second substrate (e.g. coplanar to the first substrate) is arranged Substrate is to be carried out, in particular around those points of a first substrate (workpiece) which are to be irradiated with laser beams. Depending on the requirements of the workpiece to be processed, a predetermined processing pattern (transfer pattern) can be formed at defined processing points or pixels of a workpiece using the LIFT process. Within the scope of the present invention, partial beams of a divided laser beam can be directed in point-and-shoot mode onto predetermined processing points of a workpiece.

As a result of the continuously advancing development of laser technology, it has been known for many years to use lasers to process a wide variety of materials, for example in the field of manufacturing electronic components, printed circuit boards or display elements.

When processing materials with laser radiation (e.g. laser ablation, laser welding, laser soldering, laser cleaning, laser drilling, laser sintering or laser melting), laser radiation with a Gaussian intensity distribution is currently mostly used. For many of these processes, however, it is advantageous to adapt the intensity distribution in the machining area of the workpiece to the specific machining process or the material to be machined. Therefore, optimization of the laser process by changing the intensity distribution in the processing plane is increasingly being investigated. In order to adapt the intensity distribution, it is known to subject the laser radiation generated by a laser radiation source to beam shaping, which offers considerable potential for optimizing the development of the laser process.

As already mentioned, the laser radiation generated by a laser radiation source typically has a Gaussian intensity distribution or a Gaussian beam profile in relation to its beam cross section. However, laser beams can be shaped by changing the intensity distribution using suitable beam shaping techniques. In order to form an intensity distribution of a laser beam, either its phase, its amplitude or both can be modulated together. Accordingly, phase modulators, amplitude modulators or phase and amplitude modulators are used, for example in the form of diffractive beam shapers. Diffractive beam shapers (Diffractive Optical Elements, abbreviated DOE) for adjusting far-field intensities NEN can be produced as phase elements in glass or other transparent materials.

Furthermore, the shape of an intensity distribution can take place through refraction and reflection at optical elements. Correspondingly, shaped refractive or reflective elements such as deformed or deformable mirrors or transmissive elements with a geometric deformation of the surface or shape are used. The individual partial beams of a laser beam incident on the refractive or reflective optical element fall on differently curved surfaces and are reflected or refracted on them. After being formed by the element, the totality of the partial beams forms a new intensity distribution. An example of such beam shaping is the transformation of a Gaussian laser beam into a top-hat shaped laser beam, also known as a Gaussian-to-Top-Hat beam shaper. Such a beam shaper can also be used in the laser processing device according to the invention. The geometric deformation of the surface required for beam formation can be calculated using analytical, numerical or iterative methods (e.g. superimposition of Zernike polynomials).

However, diffractive beam-shaping elements can also be in the form of beam splitters (in the context of the present invention, the function of the DOE as a beam splitter is decisive). Binary grids or blazed gratings are mentioned as examples in this context. Due to the geometry of the diffractive structure, constructive interference occurs on a rectangular grating in spatial frequency space (k-space). Various arrangements of active diffraction orders (constructive interference) can be realized using numerical algorithms. Here, the angular separation of the diffraction orders must be large enough compared to the far-field divergence of the incident laser radiation, since otherwise interference disturbs the arrangement of the active diffraction orders.

However, such unchangeable DOEs are increasingly being replaced by programmable modulation units for dynamic shaping of the laser radiation. The spatial and temporal intensity distribution of laser radiation emitted by a laser radiation source can be adjusted with programmable modulation units. Such programmable modulation units are also referred to as "spatial light modulator (SLM)". In principle, spatial light modulators can also be used for beam splitting.

A wide variety of laser radiation sources can be used in laser processing. For precise material removal, the aim should be as small a focus as possible with a laser that has the shortest possible wavelength. Today, nanosecond lasers in the IR, VIS or UV range are used as standard. For efficient material processing, laser radiation must be used with a wavelength that is absorbed by the material to be removed from the workpiece to be processed. Laser radiation with wavelengths in the near infrared and VIS range are less suitable for some materials, unless short pulse durations in the picosecond and femtosecond range are used.

So-called solid-state lasers, in particular Nd:YAG lasers, are often used, for example, for laser processing. These lasers can be precisely tailored to the respective application in terms of the achievable pulse duration, pulse energy and wavelength.

A major challenge in the laser processing of workpieces is to use laser radiation with higher average power and to apply it to the workpiece in the form of laser spots. This is opposed to heat effects, e.g. heat accumulation in the workpiece. In order to avoid this, either the generated laser power can be distributed over a large area and quickly (e.g. by fast scanning) on the workpiece, or the power is directed - e.g. in the form of beam splitting - to several processing points on the workpiece. The present invention makes use of both possibilities. To this end, it is known to reflect laser radiation on mirrors and to deflect it onto specific points on a workpiece surface to be machined. An arrangement of several mirrors of this type can be combined in one structural unit and form a mirror scanner. For example, galvanometrically driven mirror scanners (galvanometer scanners) are known, the associated mirrors of which can be rotated by a defined angle via a rotary drive. In this way, a laser beam incident on such a mirror can be directed at different points on the workpiece.

As mentioned, laser processing techniques that allow workpieces to be processed in parallel are generally known. The laser processing devices used for this can also be referred to as multi-beam systems, in particular because they are based on the division of a laser beam generated by a laser radiation source into a plurality of partial beams. The workpiece is therefore not processed with the output beam generated by the laser radiation source, but with the partial beams. The partial beams projected onto the workpiece are shown in a defined spot pattern on the workpiece. at With the known processing methods, the partial beams, and thus the spot pattern, are moved simultaneously and synchronously over the workpiece to be processed. Although it is known to decouple individual partial beams at various points on the workpiece and to adapt the spot pattern to the processing points present, such a procedure can basically only be used to process periodic structures or implement periodic processing patterns.

In addition to the processing of periodic structures or processing patterns, there are often non-periodic or partially periodic structures (ie there are non-periodic or partially periodic processing points) that cannot be processed with the known laser processing techniques of multi-beam processing, especially in the field of electronics can only be dealt with insufficiently. The advantage of such a multi-beam processing lies in the multiplication of the processing speed due to the parallel processing that is made possible. Accordingly, there is a great need to extend this advantage to multi-beam laser processing of non-periodic structures.

The following prior art appears to form the technical background of the present invention:

the U.S. 2005/0 056 626 A1 discloses an apparatus for applying laser energy to a workpiece, comprising at least one laser energy source that provides at least one laser beam, a plurality of laser beam modules arranged to selectively direct the at least one laser beam to a plurality of target portions on a workpiece that together cover a target area, the plurality of laser beam modules additionally acting to focus the at least one laser beam onto the workpiece without an intervening f-theta lens.

From the U.S. 2003/0 019 854 A1 a system for applying energy to a substrate is known, comprising at least one dynamically steerable source of radiant energy providing a plurality of beams, each beam propagating in a dynamically selectable direction; and a plurality of independently positionable beam steering elements, some of the beam steering elements receiving the plurality of beams and directing them to selectable locations on the substrate.

From the DE 103 08 708 A1 discloses a device for applying laser radiation to an object, comprising a laser light source for generating laser radiation, a two-dimensional array of influencing elements which can deflect and/or let through the laser radiation emanating from the laser light source in such a way that predeterminable locations on the object are exposed to laser radiation , A two-dimensional array of lens elements that can focus the laser radiation or parts of the laser radiation onto the surface of the object to be acted upon, the array of lens elements being arranged between the laser light source and the array of influencing elements.

the U.S. 2006/0 055 905 A1 discloses a lithographic apparatus comprising an illumination system that provides a beam of radiation; a diffraction grating splitting the beam into a plurality of sub-beams; an array of individually controllable elements configured to direct the plurality of sub-beams of radiation onto associated individually controllable elements in the array of individually controllable elements to pattern the beam; and a projection system that projects the patterned beam onto a target portion of a substrate.

the U.S. 7,227,618 B1 relates to a pattern creation system for generating two-dimensional images on a surface, comprising a light source and one or more zone plate modulator (ZPM) arrays. The ZPM arrays consist of zone plate modulation diffractive elements capable of either diffracting or reflecting incident light according to the image data. In a high-resolution pattern creation system, ZPM arrays are used as spot array generators. A complete, high-resolution image is generated by scanning individual points of light in the spot array using a subfield scanner.

Based on the foregoing, it is the object of the present invention to provide a laser processing device and a method for laser processing a workpiece, which allows rapid and parallel processing of multiple processing points of the workpiece even with a non-periodic or partially periodic distribution of processing points on the workpiece is enabled.

The stated object is achieved with a device having the features of patent claim 1 and a method having the features of patent claim 34.

1. a. eine Laserstrahlungsquelle, die dazu eingerichtet ist, einen Laserstrahl zu erzeugen und entlang eines optischen Pfades in Richtung des Werkstücks auszusenden;
2. b. eine der Laserstrahlungsquelle in Strahlrichtung nachgeordnete Strahlteilungseinheit, die dazu eingerichtet ist, den Laserstrahl in ein Bündel von Teilstrahlen aufzuteilen;
3. c. eine der Strahlteilungseinheit in Strahlrichtung nachgeordnete optische Steuereinheit, umfassend eine aus einem Array von reflektiven Mikroscannern gebildete reflektive optische Funktionseinheit, wobei die optische Steuereinheit dazu eingerichtet ist,
   • • aus dem Bündel von Teilstrahlen eine beliebige Anzahl von Teilstrahlen in beliebiger räumlicher Kombination zu selektieren und auf das Werkstück zu richten,
   • • zumindest einen, vorzugsweise einen jeden, der auf das Werkstück gerichteten Teilstrahlen unter Einsatz eines dem jeweiligen Teilstrahl zugeordneten Mikroscanners des Arrays von Mikroscannern innerhalb eines vorgegebenen Teilstrahl-Scanbereichs des jeweiligen Teilstrahls zu positionieren und/oder zu bewegen.

The laser processing device on which the invention is based is provided for processing predetermined processing points of a workpiece. The laser processing device includes

1. a. a laser radiation source configured to generate and emit a laser beam along an optical path toward the workpiece;
2. b. a beam splitting unit which is arranged downstream of the laser radiation source in the beam direction and is set up to split the laser beam into a bundle of partial beams;
3. c. an optical control unit arranged downstream of the beam splitting unit in the beam direction, comprising a reflective optical functional unit formed from an array of reflective microscanners, the optical control unit being set up for this purpose,
   • • select any number of partial beams in any spatial combination from the bundle of partial beams and direct them onto the workpiece,
   • Positioning and/or moving at least one, preferably each, of the partial beams directed onto the workpiece using a microscanner of the array of microscanners assigned to the respective partial beam within a predetermined partial beam scanning range of the respective partial beam.

The laser processing device according to the invention is characterized in that the laser processing device comprises an optical functional unit which is arranged between the beam splitting unit and the reflective optical functional unit, the optical functional unit comprising a lens array of lenses, the partial beams (T) belonging to the bundle of partial beams pass through the lens array on a first beam path up to reflection at the reflective optical functional unit, and after reflection at the reflective optical functional unit, at least some of the partial beams reflected there again pass through the lens array on a second beam path, namely in such a way that a respective partial beam appears the second beam path passes through a lens of the lens array which is arranged adjacent to a lens of the lens array through which the partial beam passes on the first beam path.

The microscanners are preferably each set up to change or manipulate a beam path of a partial beam impinging on a respective microscanner and reflected there in two independent coordinate directions. With a laser processing device according to the invention, complex folding of the partial beams in the beam path can be avoided. Furthermore, the array arrangement of the microscanners enables dense packing, as a result of which the structure of the laser processing device can be made more compact overall, since the beam paths would otherwise be very long with small beam divergence. Compared to similar systems known from the prior art, the present design of the laser processing device is therefore significantly more compact. Furthermore, individual components can be adjusted more easily. Above all, it is possible in a particularly simple manner to implement 2D distributions of laser spots in combination with an individual scan function for each partial beam.

Furthermore, the optical assemblies are clearly grouped and not randomly distributed over the structure, which makes the laser processing device significantly more robust and therefore more process-stable.

First of all, it should be noted that the laser processing device according to the invention, due to the (at least partially) reflective design, takes up less installation space than comparable laser processing devices designed to be purely transmissive.

Optionally, the laser processing device can also include a beam positioning unit, in particular in the form of a galvanometer scanner, a pivot scanner or a two-axis single-mirror scanner, which is set up to carry out a rough positioning of the partial beams directed onto the workpiece relative to the workpiece, namely by positioning a the master scan area including the partial beam scan areas relative to the workpiece and/or is set up to move the partial beams directed onto the workpiece over the workpiece, preferably synchronously and simultaneously, namely by moving the master scan area including the partial beam scan areas relative to the workpiece.

The master scan area is a spatially spanned area on the workpiece, which includes the maximum number of partial beams that can be generated on the workpiece by the beam splitting unit. The size of the master scan area is essentially determined by the division of the laser beam into partial beams by the beam splitting unit predetermined. Furthermore, the master scan area includes all sub-beam scan areas of the maximum number of sub-beams imaged on the workpiece. Depending on the application, however, it can be provided that only a predetermined number of partial beams are actually directed onto the workpiece. A partial beam scanning area is understood to be an area in which a respective partial beam can be individually positioned and/or moved on the workpiece, for example using the optical control unit, in particular the reflective optical functional unit. The part Beam scan areas are smaller than the master scan area. The sub-beam scan areas located within the master scan area can be arranged at a distance from one another, adjoin one another or overlap. The partial beams located within the master scan area and directed onto the workpiece can be moved together (preferably simultaneously and synchronously) over the workpiece, the master scan area can therefore be directed (scanned) to different locations on the workpiece. A respective sub-beam can therefore experience two scanning or positioning movements, for example, namely when aligning the master scan area on the workpiece and when positioning or moving within the respective sub-beam scan area.

As explained above, the beam positioning unit can be an "optional" component of the laser processing device according to the invention. Even without a beam positioning unit, different points of a workpiece can be processed with the laser processing device according to the invention, for example by arranging a workpiece to be processed in a workpiece holder (e.g. on an xy table) and positioning it relative to the laser processing device according to the location to be processed. The laser processing device can also be positioned and/or moved relative to a workpiece arranged in a fixed position, for example by means of a corresponding axis arrangement. Then, at the corresponding points, the partial beams directed onto the workpiece can be positioned or moved within the respective partial beam scanning areas. It is also possible to approach the workpiece locations to be machined from a combined infeed of the workpiece relative to the laser machining device on the one hand and positioning of the partial beams within the master scan range relative to the workpiece on the other.

A laser processing device comprising a beam positioning unit makes it possible to move the partial beams or associated laser spots directed onto the workpiece simultaneously and synchronously over the workpiece for positioning and processing. On the one hand, the partial beams or associated laser spots within the master scan area can be shifted and positioned relative to the workpiece. However, it also enables simultaneous and synchronous (scanning) processing of different parts of the workpiece. Alternatively, however, individual partial beams can also undergo a scanning movement—which is carried out independently of the beam positioning unit—within the respective partial beam scanning regions. However, the laser processing device can also be used without further ado for parallel point-and-shoot processing of a plurality of processing points. In point-and-shoot processing, a laser beam (here a specified number of partial beams) is directed at different processing points on the workpiece (“point”), as the term itself already expresses. Processing is carried out at these points by applying ("shooting") laser pulses. A positioning or processing movement of the laser spots during the laser processing (application of laser pulses) on the workpiece is therefore not absolutely necessary, even a one-off alignment can (depending on the processing task) be sufficient. At the same time, different parts of the workpiece can also be processed by means of point-and-shoot processing. Because between the point-and-shoot steps, the workpiece can be positioned relative to the laser processing device or vice versa in order to direct the laser spots to different areas to be processed. The same can also be done with a beam positioning unit, with which a realignment of the spot pattern lying within the master scan area on the workpiece can be carried out at a point on the workpiece after processing has taken place.

A decisive advantage of the present invention is that non-periodic or part-periodic processing patterns (i.e. non-periodic or part-periodic processing points distributed on a workpiece) can also be processed with the laser processing device according to the invention, either by way of a simultaneous and synchronous The movement of the partial beams or associated laser spots directed onto the workpiece is carried out over the workpiece or by way of the above-mentioned point-and-shoot processing. With the laser processing device according to the invention, the individual partial beams of a multi-beam system directed at the workpiece can be positioned individually on the workpiece in a partial beam scan area on the one hand, and on the other hand the number and the spatial distribution of the partial beams in a master scan area (this is defined by the lateral extent of a the area including the partial beams directed onto the workpiece) can be adjusted in a targeted manner.

With the laser processing device according to the invention, workpieces with a defined or predetermined pattern of imperfections, laser holes or other areas to be machined (the imperfections, laser holes or other areas to be machined can be arranged periodically, non-periodically or semi-periodically) with greater flexibility edit be served. Accordingly, “processing points” are generally referred to below, whereby “processing points” can mean both defects, laser drilling and other processing points (e.g. the points to be machined in the LIFT process or the points to be machined with laser drilling). In both cases, the workpiece to be machined can have a periodic, non-periodic or part-periodic structure in relation to the machining points on the workpiece surface, ie the machining points on the surface are based on a two-dimensional view in a planar periodic, non-periodic or part- arranged in periodic patterns. Scanning processing of a workpiece is also made possible with the laser processing device according to the invention, ie the partial beams are moved over the workpiece via a beam positioning unit or using the optical control unit, while laser pulses are applied to the workpiece

The bundle of partial beams provided by the beam splitting unit of the laser processing device initially likewise preferably provides a periodic arrangement of partial beams. Instead of periodically arranged distributions of the partial beams, the bundle of partial beams can also include any spatial combination of partial beams or such a free spatial arrangement can be set with the beam splitting unit. Only with the optical control unit can a wide variety of partial beams be deflected from the optical path, so that the partial beams can be selected in such a way that a desired number of partial beams (or associated laser spots) on the workpiece in any spatial arrangement based on a spot pattern imaged on the workpiece is mapped. If a bundle of partial beams can be generated from the laser beam by the beam splitting unit, which in principle enables laser spots arranged in a spot matrix, for example a 4 by 4 spot matrix of laser spots, to be imaged on the workpiece, the optical control unit can be used to set whether a certain partial beam or laser spot of the 4 by 4 spot matrix is actually forwarded in the direction of the workpiece and imaged on the workpiece. Accordingly, it can be freely set which of the partial beams providing the spot matrix of 4 by 4 laser spots is actually imaged on the workpiece in the form of a laser spot. The spatial arrangement or pattern of the laser spots is therefore in any permutation, taking into account the basic matrix predefined by the beam splitting unit freely adjustable. In contrast to the prior art described at the beginning, with the present invention not only individual rows or columns of a spot matrix imaged on the workpiece can be selected (or the partial beams corresponding thereto), but also any permutations of an m × n matrix of laser spots ( or associated partial beams). It is not necessary to specify a specific spatial pattern or a number of partial beams; rather, any partial beams of the bundle of partial beams can be selected via the optical control unit and forwarded in the direction of the workpiece. With the laser processing device proposed here, parallel processing of different processing points within a master scan area is made possible on the one hand, and on the other hand individual positioning of each partial beam in a partial beam scan area is made possible, with the partial beam scan area having a smaller lateral extent than the aforementioned master scan area. The master scan area thus includes a number of partial beam scan areas corresponding to the number of partial beams directed onto the workpiece.

Depending on the size of the area to be processed, it may be sufficient to position the workpiece once relative to the laser processing device, for example in the case where the area comprising the processing points is smaller than the master scan area accessible with the laser processing device, i.e. the area that the laser spots can be achieved by positioning using the beam positioning unit (without relative displacement between the workpiece and the laser processing device). For such a preferred embodiment of the invention (i.e. the possibility of selecting the master scan area as large as possible, the system must be able to compensate for the distortion of a lens (e.g. an F-theta lens) that is also associated with the laser processing device, which presently made possible with the laser processing device according to the invention or the method on which this is based.This will be explained in more detail later.

If, on the other hand, the area of the workpiece to be processed is larger than the master scan area, it is necessary to calculate a processing path or displacement path related to a relative displacement between the workpiece and the laser processing device. The displacement path can contain a number of different machining positions (ie relative positions between the workpiece and the laser machining device). The required number of processing positions corresponds to the number of required processing steps. After positioning the workpiece relative to the laser processing device (according to one of the processing positions), the number and spatial position of the images on the workpiece determined laser spots or partial beams based on the number and arrangement (i.e. the pattern) of the processing points present in this processing area. In the case of non-periodic or partially periodic patterns of processing points, individual positioning of one or more partial beams can also be carried out. The optical control unit makes it possible to position all of the partial beams individually and autonomously within a predetermined partial beam scanning area. In this way, the partial beams can be directed exactly onto the processing points of the workpiece, even in the case of non-periodic or part-periodic processing patterns. Furthermore, the optical control unit makes it possible to set an individual movement (ie scanning) of the partial beams directed onto the workpiece in the partial beam scanning area. The beam positioning unit can therefore initially be used for coarse positioning or a coarse scan of the partial beams within the master scan area relative to the workpiece. Furthermore, using the optical control unit, individual positioning (fine positioning) or movement of the partial beams directed at the workpiece within a partial beam can be carried out -Scan area take place. It should be emphasized at this point that a rough positioning in no way means that the resolution during positioning is low. Rather, very precise positioning can already take place during the rough positioning (eg using the beam positioning unit). For example, the coarse positioning can also be understood in the sense of an "initial positioning" of the partial beams or associated laser spots projected onto the workpiece, after which fine positioning (this can be as further positioning, individual positioning or secondary positioning) of the partial beams or associated laser spots can take place . However, "fine positioning" does not necessarily mean that the positioning is more precise or takes place with a higher spatial resolution.

On the basis of an input data record, which reflects the processing points present or specified on the workpiece or their spatial distribution, the necessary processing path, the number of processing steps, as well as the number and position of the individual processing steps required for processing the processing points present there laser spots or partial beams projected on the workpiece can be determined. The aforementioned determination can be carried out, for example, under the premise of the fastest and most efficient method management or processing possible.

As already mentioned, the laser processing device according to the invention comprises a laser radiation source which is set up to generate a laser beam and emit it along an optical path in the direction of the workpiece. The emitted laser beam can pass through optical components between the laser radiation source and the workpiece and be reflected, refracted, divided or deflected by them. In the present case, the generated and emitted laser beam can be understood to mean a continuous laser beam, but in particular a laser pulse. Short-pulse or ultra-short-pulse lasers can preferably be used as laser radiation sources in the laser machining device proposed with the invention. In principle, the use of continuous-wave (cw) lasers as a laser radiation source can also be considered.

According to the invention, the device also comprises a beam splitting unit arranged downstream of the laser radiation source in the beam direction. This is set up to split the laser beam into a bundle of partial beams. The partial beams are distributed in a predetermined spatial pattern. Starting from the laser radiation source, a collimated laser beam therefore impinges on the beam splitting unit. The beam splitting unit splits the laser beam into a bundle of identical partial beams, each of which has a defined angle to one another. In addition, a beam shaping element can be provided between the laser radiation source and the beam splitting unit, with which a large number of partial beams with a predetermined intensity distribution, for example a top-hat intensity distribution or a ring-shaped intensity distribution. In this way, a multi-tophat pattern of laser spots can be generated on the workpiece.

In this context, the term "beam direction" refers to the course of the laser beam. The specification of the beam splitting unit "downstream" in relation to the laser radiation source in the beam direction means that the beam splitting unit is arranged along the optical path behind the laser radiation source. The laser beam is therefore first generated and only then enters the beam splitting unit or impinges on it. However, the use of the term “beam direction” here does not rule out the possibility that individual optical components of the laser processing device are passed through several times by the partial beams.

The beam splitting unit can be a diffractive optical element (DOE), for example. For the relevant details, reference is made to the introductory part of the description. In principle, however, there is also a use of a principle from the prior art Technology known "spatial light modulators" considered as a beam splitting unit, as long as beam splitting is guaranteed with the latter. A spatial light modulator is an optical component that varies the phase and/or the amplitude of a laser beam locally as a function of location. Thanks to the Spatial Light Modulator, an incoming laser beam is phase and/or amplitude modulated. Spatial light modulators for transmission are known from the prior art, which locally generate a phase delay in a laser beam passing through the spatial light modulator. Furthermore, spatial light modulators are known which locally generate an amplitude weakening in a laser beam passing through the spatial light modulator. Both types of spatial light modulators act as diffractive elements, behind which diffraction images result, which depend on the exact spatial arrangement of the delaying or attenuating areas. The generated diffraction pattern, ie the rays of different orders on which the diffraction pattern is based, can also be regarded as partial rays in the sense of the present invention. However, it should be emphasized that it is preferred according to the invention to use a beam splitting unit based on a DOE.

Furthermore, variable spatial light modulators are known from the prior art, in which the intensity distribution of the modulated laser beam that results on the workpiece can be adjusted electronically. Such variable spatial light modulators can also be based on a locally varying phase delay and/or amplitude attenuation. As a rule, such spatial light modulators are not transmitted through, but used in a reflection configuration. Spatial light modulators, which are based on a reflection of laser radiation on a semiconductor surface in front of which a liquid crystal layer is arranged, may be mentioned as examples at this point. The birefringent properties of the liquid crystal layer can be adjusted locally in a targeted manner, for example by applying an electric field via microstructured electrodes. Corresponding spatial light modulators are marketed by the company Hamamatsu under the name LCOS (“Liquid Crystal on Silicon”) spatial light modulator. Furthermore, transmitting variable spatial light modulators are also known, which are sold, for example, by Jenoptik under the designation “Liquid Crystal Light Modulators Spatial Light Modulator-S”. The diffraction images generated with such variable spatial light modulators can also be regarded as partial beams within the meaning of the invention, but the previously described variant of the design of the beam splitting unit in the form of a diffractive beam splitter is to be preferred.

Furthermore, amplitude-modulated variable spatial light modulators are mentioned, which are based on micromechanical micromirror arrays. The individually controllable micro-mirrors make it possible to selectively "hide" spatial areas from the cross-section of a laser beam. A diffraction pattern then results from the diffraction of the incident laser radiation on a "grating" in a reflection arrangement. Diffraction images generated in this way can basically also be regarded as partial beams within the meaning of the present invention.

As already mentioned, any number of partial beams in any spatial combination can be selected from the bundle of partial beams with the optical control unit also associated with the laser processing device and directed onto the workpiece. A first number of partial beams can be forwarded along the optical path in the direction of the workpiece. Furthermore, a second number of partial beams can be deflected or absorbed from the optical path by a corresponding component of the optical control unit or a beam selection unit, which means that the second number of partial beams do not impinge on the workpiece. The amount of those of the first and second number (i.e. the partial beams transmitted in the direction of the workpiece and the partial beams derived or absorbed from the optical path) depends on the number of processing points of the workpiece area that are in the area of the master scan area in a specific processing step . For example, if the beam splitting unit makes it possible to divide the laser beam into a 16 by 16 partial beam array and align it with a workpiece, and if there are only four processing points or defects in the area of the workpiece accessible to the master scan area, then only four partial beams need to be processed to be provided. The excess partial beams can then be deflected or removed (e.g. absorbed) from the optical path with the optical control unit or a beam selection unit.

As mentioned, the optical control unit includes a reflective optical functional unit. It is not excluded that the optical control unit or the reflective optical functional unit associated with the control unit has a plurality of components or components. A reflective optical functional unit is to be understood within the meaning of the invention that partial beams impinging on the reflective optical functional unit or components thereof are reflected or deflected. The reflective optical function The device is preferably designed such that each partial beam impinges on a reflective component of the reflective optical functional unit, the reflective component being a reflective beam direction manipulation unit. This will be explained in more detail later.

In the case of non-periodic or semi-periodic processing patterns, it may also be necessary to individually adjust individual partial beams that are directed at the workpiece and lie within the master scan area according to the position of the processing point to be processed with the respective partial beam within a specified partial beam scan area position. The optical control unit can also be used to carry out an individual movement (scanning movement) of the partial beams directed onto the workpiece within the respective partial beam scanning area.

As mentioned, the laser processing device can also (optionally) include a beam positioning unit, in particular in the form of a galvanometer scanner, a pivot scanner or a two-axis single-mirror scanner, which is set up to carry out a rough positioning of the partial beams directed onto the workpiece relative to the workpiece, namely by positioning a master scan area including the sub-beam scan areas relative to the workpiece. At the respective positions of the master scan areas (and thus the partial beams) set via the coarse positioning, individual fine positioning of the partial beams within predetermined partial beam scan areas of the respective partial beams can take place after the coarse positioning. A beam positioning unit designed as a galvanometer scanner can have one or more rotary drive(s) which are set up to move mirrors provided in the beam positioning unit for the purposeful deflection and positioning of the partial beams. Galvanometer scanners for use in laser processing apparatus are well known. With the beam positioning unit, all partial beams directed onto the workpiece are infed. The use of a pivot scanner or a two-axis single-mirror scanner, ie a beam deflection system that enables virtual or real beam deflection in two spatial directions from one point in space, can be advantageous when using an F-sin-theta lens or an F-sin-theta lens, in particular to reduce distortion errors. An F-sin-theta lens or an F-sin-theta objective is to be understood as an objective with a rotationally symmetrical correction or distortion corresponding to the function F-sin(theta).

Alternatively or additionally, the beam positioning unit is set up to move the partial beams directed onto the workpiece over the workpiece, preferably synchronously and simultaneously, namely by moving the master scan region including the partial beam scan regions relative to the workpiece.

The beam positioning unit is subordinate to the optical control unit with regard to the beam direction or the beam path, so the beam path of the partial beams is designed in such a way that the partial beams are only directed to the Beam positioning unit impinge. The beam positioning unit can in particular be set up to image laser spots corresponding to the first number of partial beams in cooperation with the focusing unit on the workpiece. Furthermore, the beam positioning unit can be set up to move the laser spots simultaneously and synchronously over the workpiece for positioning and/or for processing. The positioning can precede the processing. Both steps can be repeated for the individual processing steps after the workpiece has been positioned relative to the laser processing device. However, it is also possible to machine a workpiece at a predetermined number of points without performing a machining movement, e.g. B. in point-and-shoot mode. It should be expressly emphasized at this point that although the partial beams directed onto the workpiece or the associated laser spots can be positioned and/or moved with the beam positioning unit, the beam positioning unit can only carry out a common positioning or processing movement of all partial beams. The individual positioning and/or movement of individual partial beams within a predetermined partial beam scanning area, on the other hand, takes place independently of the beam positioning unit, namely via the optical control unit.

As mentioned, the beam positioning unit can be, for example, a galvanometer scanner. Such a galvanometer scanner can have one or more mirrors, each of which can be rotated by a defined angle about an axis of rotation. As a result, partial beams reflected by the mirrors (or an associated master scan area) can be directed to a desired location on the workpiece within an accessible scan field. In particular when using an ultrashort pulse laser as the laser radiation source, however, the use of a polygon scanner can also be provided as the beam positioning unit. Polygon scanners are suitable in in a special way for high-resolution processing of a workpiece. With a scanner, the process times for workpiece processing can be significantly reduced. Alternatively, however, a beam positioning unit can also be provided, which is set up to statically align the partial beams or associated laser spots on the workpiece or to position the partial beams or associated laser spots on the workpiece.

As already mentioned at the outset, the invention is directed not only to the laser processing device, but also to a method for laser processing a workpiece at predetermined processing points, but using the laser processing device according to the invention. In order to avoid repetition, the features of the method according to the invention and advantageous refinements of the method proposed with the invention have already been described at this point. Of course, the features described here within the scope of the proposed method can also be used as advantageous configurations of the laser machining device proposed with the invention. The laser processing device or components thereof can therefore be set up and/or designed to carry out the method steps and/or features mentioned below.

According to the invention, a method is proposed for laser processing a workpiece at predetermined processing points using a laser processing device according to the invention, wherein after a laser beam has been generated with a laser radiation source, the laser beam is split into a bundle of partial beams and at a predetermined number of points using an optical control unit predetermined number of partial beams of the bundle of partial beams is directed onto the workpiece in any spatial combination, and wherein the partial beams directed onto the workpiece are positioned and/or moved within a predetermined partial beam scanning range.

It should be emphasized that within the scope of the terminology used in the present patent application, positioning of partial beams directed onto the workpiece (regardless of whether this is coarse or fine positioning) means that positioning with the laser (laser radiation source) switched off is carried out, i.e. no laser spot is imaged on the workpiece during the actual positioning. Only then is the laser radiation source switched on and laser radiation (in the form of partial beams directed at the workpiece or associated laser spots) is applied to the workpiece. Laser radiation (e.g. in the form of laser pulses) is only applied in a second step (after positioning). Such a modulation can be carried out via a control unit or the laser radiation source.

1. a. Positionieren des Werkstücks relativ zu der Laserbearbeitungsvorrichtung, oder
2. b. Positionieren der auf das Werkstück gerichteten und innerhalb eines Master-Scanbereichs liegenden Teilstrahlen relativ zu dem Werkstück unter Einsatz einer Strahlpositionierungseinheit, oder
3. c. Positionieren des Werkstücks relativ zu der Laserbearbeitungsvorrichtung und der auf das Werkstück gerichteten und innerhalb eines Master-Scanbereichs liegenden Teilstrahlen mit einer Strahlpositionierungseinheit.

According to an advantageous embodiment of the method according to the invention, prior to positioning the partial beams in the respective partial beam scanning areas, the partial beams directed onto the workpiece can be roughly positioned at a predetermined number of points, in particular by arranging the workpiece in a workpiece holder and

1. a. Positioning the workpiece relative to the laser processing device, or
2. b. positioning the partial beams directed at the workpiece and lying within a master scan range relative to the workpiece using a beam positioning unit, or
3. c. Positioning of the workpiece relative to the laser processing device and the partial beams directed onto the workpiece and lying within a master scan area with a beam positioning unit.

The workpiece holder can be a component of the laser processing device as such, and the workpiece holder can also be designed as a separate component. In the simplest case, the workpiece holder can be designed in the form of a support plate or a table, on which the workpiece can be positioned based on weight. Other configurations of the workpiece holder are also conceivable, as is the provision of suitable fastening or positioning means for fastening or positioning the workpiece in the workpiece holder. The workpiece holder can also be an xy table that can be moved in a horizontal plane. Correspondingly, the workpiece can be moved over the xy table in a horizontal plane or work plane.

According to the method, a number of processing steps (this corresponds to the number of points at which the partial beams directed onto the workpiece - in particular the partial beams lying within the master scan area - must be positioned relative to the workpiece), a relative position of the workpiece to the laser processing device required to carry out the respective processing steps, a processing path comprising the relative positions of the respective processing steps and the respective processing steps for processing the processing points required number of partial beams, the spatial arrangement of the partial beams or associated laser spots of a spot matrix and the individual position of each partial beam in the specified partial beam scanning area are determined and defined. It is noteworthy that there can often be a number of possible solutions (different processing paths, spot patterns at different processing points, etc.). An efficient processing strategy that takes the aforementioned aspects into account can be determined using a suitable algorithm. At this point, efficient means that a strategy is determined in which, on average, as many partial beams as possible are positioned on the workpiece in order to reduce the total processing time for the respective processing task. This can be carried out using a control unit (this can comprise a data processing unit), it being possible for the control unit to be part of the laser processing device or to be an external control unit. The control unit is preferably connected to the optical control unit in terms of control technology. The control unit can include sub-control units that can be assigned to the respective components (eg the reflective optical control unit) of the laser processing device.

1. a. Erzeugen eines Laserstrahls von der Laserstrahlungsquelle und Aussenden des Laserstrahls entlang eines optischen Pfades in Richtung des Werkstücks;
2. b. Selektieren einer beliebigen Anzahl von Teilstrahlen in beliebiger räumlicher Kombination aus dem Bündel von Teilstrahlen und richten der selektierten Teilstrahlen auf das Werkstück, wobei dies unter Einsatz einer eine reflektive optische Funktionseinheit umfassenden optischen Steuereinheit erfolgt;
3. c. Positionieren und/oder Bewegen eines jeden auf das Werkstück gerichteten Teilstrahls innerhalb eines vorgegebenen Teilstrahl-Scanbereichs des jeweiligen Teilstrahls.

After positioning the workpiece relative to the laser processing device and/or vice versa, the following steps can be performed:

1. a. generating a laser beam from the laser radiation source and emitting the laser beam along an optical path toward the workpiece;
2. b. selecting any number of partial beams in any spatial combination from the bundle of partial beams and directing the selected partial beams onto the workpiece, this being done using an optical control unit comprising a reflective optical functional unit;
3. c. Positioning and/or moving each sub-beam directed onto the workpiece within a predetermined sub-beam scanning range of the respective sub-beam.

It should be emphasized at this point that according to the aforementioned method step c. a desired number of sub-beams directed onto the workpiece can be positioned and/or moved within the respective predetermined sub-beam scanning areas. It is therefore not absolutely necessary to subject all of the partial beams directed onto the workpiece to a fine positioning or a scanning movement within the respective partial beam scanning area. A one-time positioning of a partial beam (by way of a rough positioning via the beam positioning unit) can already be considered as positioning in the sense of step c. to be understood, but also a positioning of the partial beam in the partial beam scanning area carried out via the reflective optical functional unit.

Furthermore, it can be advantageous within the scope of the method according to the invention that the optical control unit is set up to, following the rough positioning and the positioning of the partial beams directed at the workpiece within the specified partial beam scanning range, at least for one of the partial beams directed at the workpiece, an individual to perform a scanning movement. Such an individual scanning movement can advantageously be carried out by means of the control unit for any number of the partial beams directed onto the workpiece, for example for all partial beams or a predetermined number of partial beams. An "individual scanning movement" means that a respective partial beam is moved within the partial beam scanning area along a specified movement path over the workpiece, so that, for example, a specified contour is "traversed" or scanned, which ultimately leads to local processing of the workpiece leads.

According to a further advantageous embodiment of the method proposed by the invention, it can be provided that, using the beam positioning unit, subsequent to the rough positioning and the positioning of the partial beams directed at the workpiece within the specified partial beam scanning range for the partial beams directed at the workpiece, a simultaneous and synchronous scanning movement is carried out. In this case, all of the partial beams directed onto the workpiece are moved simultaneously and synchronously within the respective partial beam scanning area. In this way, too, a predetermined movement path of the respective partial beams within the respective partial beam scan areas can be implemented, so that within the partial beam scan areas, for example, a predetermined contour can be "traversed" or scanned, which ultimately leads to local processing of the workpiece .

According to a further advantageous embodiment of the method proposed by the invention, it can be provided that using the optical control unit and/or the beam positioning unit following the rough positioning and, if necessary, the positioning of the partial beams directed onto the workpiece within the predetermined partial beam scanning area for a predetermined Number of partial beams directed at the workpiece a positioning correction of Positioning errors, in particular resulting from distortion errors of an optical functional element, is performed.

The optical control unit can therefore be used to correct optical positioning errors of the partial beams on the workpiece, which can arise due to the distortion of an F-theta lens or lenses that have been corrected in some other way. In addition to the positioning of the respective partial beams on the workpiece (e.g. in order to carry out a laser drilling), a correction of positioning errors can also be carried out according to the method described here or with the laser processing device described here. In the event that, for example, a 2 x 2 matrix of laser spots (partial beams) projected onto the workpiece is scanned (moved) over the workpiece with a beam positioning unit through an F-theta objective (an F-theta lens) or an otherwise corrected objective, then the matrix of the laser spots (partial beams) can be distorted at certain scan angles, especially at scan angles > (0.0) with respect to the axis of symmetry of the lens. The matrix of the laser spots or partial beams is then rotated and the distances between the laser spots change due to the optical distortion of the said F-theta lens and the present configuration of the beam positioning unit. With the method described here or the laser processing device described here, this effect can be actively compensated, e.g. by adjusting the spot positions for each scan angle set with the beam positioning unit by means of a fine positioning of the laser spots or partial beams carried out (by the control unit and/or the beam positioning unit). (this can also be referred to as using a correction matrix) so that the positions of the matrix of laser spots are corrected for scan angle adjustment with scan angles of (0,0). In order to be able to use a (relatively large) scan field (master scan area) of the beam positioning unit in the best possible way for parallel processing, the position errors of the laser spots or partial beams must be actively compensated. As described above, this is made possible by using the optical control unit, in particular the reflective optical functional unit (in particular using a correction matrix) and a beam positioning unit. In this way, positioning errors can be compensated individually for each partial beam as a function of the scan angle with a fixed configuration of beam positioning unit and F-theta lens. The mentioned correction matrix can be determined using an optical measuring system, which can preferably be a measuring system arranged in the focus of the F-theta lens.

The correction matrix mentioned contains the necessary corrections of the fine positioning system (the reflective optical functional unit) to correct position errors of the partial beams that are induced by the beam positioning unit and an associated F-theta lens. The error depends on the scanning angle of the beam positioning unit.

Taking the above into account, it can be stated that the partial beam scan range of a partial beam directed onto the workpiece is composed of a scan vector for correcting the stated position error of the partial beam and a scan vector for positioning the partial beam on the target position.

According to a further advantageous embodiment of the method, it can be provided that using the beam positioning unit, following the rough positioning and the positioning of the partial beams directed at the workpiece within the specified partial beam scanning area, a simultaneous and synchronous scanning movement for the partial beams directed at the workpiece along a predetermined scanning path is carried out, with the execution of the scanning movement using the optical control unit, in particular the reflective microscanner, for a predetermined number of the partial beams directed onto the workpiece, a dynamic positioning correction of positioning errors, in particular resulting from distortion errors of an optical functional element, is carried out, preferably under Use of a correction matrix. When performing a scanning movement, the laser radiation source is switched on (in contrast, the laser radiation source is switched off during positioning - be it coarse positioning or fine positioning), so that the partial beams directed onto the workpiece can be moved over it accordingly. This allows "long vectors" to be scanned (executed the scan movement) across the workpiece using the beam positioning unit, while at the same time being able to correct distortion errors more dynamically. Subsequent to the aforementioned rough positioning with the beam positioning unit, the partial beams directed onto the workpiece can then be positioned within the respective partial beam scanning regions. Following such positioning and any correction of static positioning errors of the partial beams (see the previous description), according to this embodiment, the partial beams can be moved using the beam positioning unit along a scan path that can include the entire master scan area, wherein the optical control unit detects the positioning error/distortion error of each Partial beams compensated dynamically using the correction matrix (real-time compensation).

This is explained using the following example: With the laser processing device, a 1×4 matrix of partial beams or associated laser spots is arranged on the workpiece. Then 4 parallel lines are scanned across the workpiece. The length of the parallel lines corresponds to the length of the master scan area. The beam positioning unit carries out the scanning movement, while the optical control unit, i.e. the respective microscanner, dynamically compensates for the position errors of the partial beams along the scanning path.

Advantageous configurations of the laser processing device proposed with the invention, in particular those advantageous configuration variants specified in the dependent claims, are explained in detail below. The dependent claims relate to advantageous refinements and developments of the present invention. The features mentioned in the subclaims can be used in any combination to develop the laser processing device according to the invention and the method according to the invention, insofar as this is technically possible. This also applies if such combinations are not expressly clarified by corresponding back references in the claims. In particular, this also applies beyond the category boundaries of the patent claims. The configuration features described in connection with the laser processing device according to the invention can also be used as possible advantageous configurations of the method according to the invention. For reasons of clarity, advantageous configurations relating to the optionally present beam positioning unit have already been explained above. Nevertheless, this can also be combined with the other technical configurations described below or with the features specified in the dependent claims.

1. a. eine Fokussiereinheit, die insbesondere aus einer oder mehreren hintereinander angeordneten Linsen, Linsensystemen, Spiegeln oder einer Kombination daraus gebildet ist,
2. b. einen beabstandet zur Fokussiereinheit angeordneten Linsenarray von Linsen.

According to a first configuration of the invention, the laser processing device can have an optical functional unit, which is arranged between the beam splitting unit and the reflective optical functional unit, and comprises a group of optical functional elements arranged one behind the other. In particular, it can be provided that the group of optical functional elements arranged one behind the other comprises:

1. a. a focusing unit, which is formed in particular from one or more lenses, lens systems, mirrors or a combination thereof arranged one behind the other,
2. b. a lens array of lenses arranged at a distance from the focusing unit.

A two-dimensional lens array, for example, always requires one more “row” or “column” of lenses than the array of microscanners of the reflective optical functional unit. If, for example, an arrangement of 4 by 4 microscanners is provided, an arrangement of 5 by 4 or 4 by 5 lenses in the lens array would be required.

The number of lenses in the lens array is measured in particular according to the number of lenses required to ensure that the partial beams on the second beam path (after reflection at the reflective optical functional unit) each have one in comparison to the first beam path (i.e. the beam path of the partial beams before impinging on the reflective optical functional unit) can pass directly or not directly adjacent lens.

Within the meaning of the invention, the optical functional unit can be understood in particular as an optical functional unit whose components (the focusing unit and the lens array) can be passed through by the partial beams, ie are designed to be transmissive. However, this does not rule out the possibility that individual elements of the optical functional unit can also be designed to be reflective.

According to a further advantageous embodiment of the invention, a laser processing device designed to that effect can be provided, in which the partial beams associated with the bundle of partial beams pass through the optical functional unit, in particular the focusing unit and the lens array, on a first beam path up to reflection at the reflective optical functional unit, as well as after the reflection at the reflective optical functional unit, at least some of the partial beams reflected there pass again on a second beam path through the optical functional unit, in particular the lens array and the focusing unit. When passing through the focusing unit and the lens array, the partial beams can be optically refracted. Following the beam splitting in the beam splitting unit, the partial beams accordingly propagate as bundles of collimated partial beams in the direction of the focusing unit.

Preferably, the laser processing device can also be designed such that on the first beam path each partial beam of the bundle of partial beams passes through a lens of the lens array assigned to the respective partial beam and on the second beam path at least at least part of the partial beams reflected at the reflective optical functional unit passes through a lens of the lens array assigned to the respective partial beam. On the second beam path--as will be explained later--a respective partial beam passes through a different, in particular adjacent, lens compared to the first beam path. In this context, an “assignment” is not to be understood as meaning that a partial beam passes through one and the same lens on the first beam path and the second beam path.

Provision can be made for each partial beam of the bundle of partial beams to pass through the focusing unit on the first beam path and for at least some of the partial beams reflected on the reflective optical functional unit to pass through the focusing unit again on the second beam path.

It can be provided that not all of the partial beams that have passed through the focusing unit and the lens array on the first beam path arrive in the direction of the workpiece, but rather are deflected or removed from the beam path beforehand (preferably on the second beam path) by suitable means. Accordingly, provision can be made for a predetermined number of partial beams to be deflected or absorbed from the optical path, preferably on the second beam path, so that the deflected partial beams do not impinge on the workpiece. This can be done either via a beam selection unit provided specifically for this purpose or via the reflective optical functional unit. Depending on the number of partial beams required for processing at a given position of the master scan area on the workpiece, the corresponding number of partial beams that are not required can be deflected or removed from the beam path of the partial beams.

The focusing unit can, for example, be designed as a single lens, e.g. as an asphere. In practice, however, the use of complex lens systems has proven to be advantageous, since this allows aberrations to be corrected better.

According to an advantageous embodiment of the invention, it can be provided that the bundle of the plurality of partial beams has a partial beam bundle axis before and after passing through the focusing unit on the first beam path, with respect to which the plurality of partial beams are preferably arranged symmetrically. Furthermore, it can be advantageous if the partial beam bundle axis is preferably perpendicular to a microscanner plane in which the reflective microscanners are arranged. A certain basic geometric order of the partial beams projected onto the workpiece is predetermined by such a beam splitting, it being possible with the laser processing device according to the invention to position each of the partial beams individually within a predetermined partial beam scanning range. As the partial beams pass through the focusing unit, the partial beams are made parallel to one another and focused.

According to a further advantageous embodiment of the present invention, it can be provided that the focusing unit is arranged in such a way that the axis of the partial beam bundle is offset before the partial beams impinge on the focusing unit on the first beam path in relation to an axis of symmetry of the focusing unit running along the optical path . An offset is to be understood in particular as a parallel offset by a predetermined distance. At this point, parallel offset means that the partial beam bundle axis is offset parallel to the axis of symmetry of the focusing unit. The offset of the bundle of partial beams or the partial beam axis to the axis of symmetry of the focusing unit causes the partial beam axis to run at an angle to the axis of symmetry of the focusing unit after the partial beams have passed through the focusing unit on the first beam path.

According to a further advantageous embodiment of the present invention, it can be provided that the focusing unit is arranged in such a way (the arrangement in relation to the beam splitting unit is particularly decisive) that the bundle of partial beams before and/or after passing through the focusing unit on the first beam path has a telecentric has beam path. This applies in particular after the partial beams have passed through the focusing unit on the first beam path. The telecentric property of the focusing unit has the effect that the bundle of partial beams, after passing through the focusing unit, initially propagates along the first beam path in such a way that the optical axes of each partial beam are parallel to one another. This means the following: The respective sub-beams of the bundle of sub-beams each have a bundle of a predetermined number of sub-beams (the sub-beams are focused on the workpiece). A telecentric beam path is to be understood here as meaning that these sub-beams can each be described by a main beam (the sub-beam), with the main beams being parallel to one another after passing through the focusing unit. In particular, the principal rays are aligned parallel to an axis that is tilted with respect to the axis of symmetry of the focusing unit. The axis tilting results from the offset of the partial beam tubes del axis with respect to the axis of symmetry of the focusing unit before passing through the focusing unit on the first beam path.

On the second beam path, ie on the beam path following the reflection of the partial beams at the reflective optical functional unit, the beam path or beam profile of the partial beams can be telecentric or non-telecentric at least in sections. In the case of a telecentric beam path or beam path, the reflective optical functional unit is arranged in such a way that the optical axes of the partial beams on the second beam path for the scanning angles of the partial beams set with the reflective optical functional unit, in particular the associated microscanners, result in the partial beams being again passing through the lens array parallel to each other. The maximum scan range that can be set by the microscanner is therefore necessarily limited to a range that is smaller than the diameter of the lens associated with the lens array. For the scanning function performed with the reflective optical functional unit with regard to the partial beams, this means that the respective scan field of a partial beam is smaller or significantly smaller than the distance between the partial beams on the workpiece. The degree of filling of the scan field or master scan area on the workpiece is therefore limited. In the case of a non-telecentric beam path or beam path, the arrangement of the microscanner (or the reflective optical functional unit) and the lens array is selected in such a way that the optical axes of the partial beams on the second beam path are not parallel after passing through the lens array, i.e. the optical axes describe a certain angular space. This means that the scanning area that can be set by the microscanner is or can be larger than the diameter of the respective lenses of the lens array. In this way, the scan area of each partial beam can be enlarged, the degree of filling of the scan area on the workpiece increases, and at most the scan area can even be completely covered with partial beams. However, a non-telecentric beam path behind the lens array leads to an offset of the partial beams in the entrance pupil of a focusing objective of the beam positioning unit when scanning with the partial beams with the microscanners. This leads to partial beams on the workpiece that do not hit the workpiece perpendicularly but at an angle of <90°, which can be disadvantageous for some applications but tolerable for other applications. In particular, however, the angle depends on the positioning of the focusing optics with respect to the entrance pupil of the focusing objective of the beam positioning unit. The decisive factor here is that the change in the position of the partial beam in the entrance pupil of the lens results in a change in the angle of incidence of the partial beam on the workpiece.

As already mentioned, according to a further advantageous embodiment of the present invention it can be provided that the optical partial beam axis runs at an angle to the axis of symmetry of the focusing unit after the partial beams have passed through the focusing unit on the first beam path. This is due to the fact that the focusing unit has a non-zero focal length and the partial beam axis is offset from the symmetry axis of the focusing unit.

According to a further advantageous embodiment of the present invention, it can be provided that the partial beams of the bundle of partial beams are focused on the first beam path in a plane arranged perpendicular to the optical path or to the axis of symmetry of the focusing unit, the plane preferably being between the focusing unit and the lens array is arranged. The partial beams can also easily be focused in a virtual focal plane. It can also be advantageous on the second beam path to focus the partial beams of the bundle of partial beams after passing through the lens array in said plane.

According to a further advantageous embodiment of the invention, it can be provided that the lens array comprises a lateral arrangement of lenses or lens systems (e.g. doublet lenses or triplet lenses), which are preferably arranged in a common lens plane, with the lens plane being perpendicular to the optical path or .is arranged to the axis of symmetry of the focusing unit. The lenses or lens systems associated with the lens array are preferably identical lenses or identical lens systems. The lenses or lens systems can be arranged in the lens plane in particular in the form of a lattice arrangement or hexagonal arrangement. As mentioned, the lenses of the lens array are arranged in such a way that each partial beam of the bundle of partial beams passes through a respective lens. It applies here that a partial beam passes through a lens on the first beam path and passes through another lens (preferably an adjacent lens) on the second beam path. However, it is essential that each partial beam passes through a different (own) lens on the way there, i.e. no lens is passed through by two partial beams on the way there. On the way back, each partial beam also passes through a different (own) lens, which is not identical to the lens through which it passed on the way there, but is preferably an adjacent lens.

Such an arrangement enables the partial beams to be separated into separate optical channels. Each partial beam passing through the lens array or the individual lenses is collimated by the respective lens of the lens array on the first beam path. The distance between the focusing unit and the lens array is selected such that the partial beams are essentially collimated after passing through the lens array. After the partial beams have passed through the lens array, the partial beams propagate in the respective optical channels on the first beam path until they impinge on the reflective optical functional unit.

As already mentioned, it is provided according to the invention that the reflective optical functional unit is formed from an array of reflective microscanners. The array of reflective microscanners can include a lateral arrangement of reflective microscanners, which are preferably arranged in a common microscanner plane, the microscanner plane being arranged perpendicular to the optical path or to the axis of symmetry of the focusing unit. The reflective microscanners are arranged in such a way that a partial beam is reflected by a microscanner. The angle of incidence of each partial beam on the respective reflective microscanner corresponds approximately to the initially mentioned angle between the axis of the partial beam bundle and the axis of symmetry of the focusing unit. Correspondingly, the number of reflective microscanners corresponds to the number of partial beams running along the first beam path. After a respective partial beam impinges on a reflective microscanner, the partial beam is reflected on this microscanner.

Each microscanner is preferably set up to assume a basic position and at least one first deflection position, with a microscanner located in the first deflection position being set up to deflect a partial beam impinging on the microscanner in the direction of the second beam path. Provision can also be made for each microscanner to be set up to assume a second deflection position, with a microscanner located in the second deflection position being set up to deflect a partial beam impinging on the microscanner from the optical path. If it is provided that the respective microscanners can assume two deflection positions, it can be advantageous if the respective partial beams are deflected in the first and second deflection positions of the respective microscanners along a first and second spatial direction, with the first and second spatial direction perpendicular to the Run axis of symmetry of the focusing unit.

Furthermore, it can be provided that a deflection angle can be set flexibly and dynamically with the respective microscanners for the respective partial beam impinging on the microscanner. A dynamic setting means that each microscanner can be based on its own scan program, which includes, for example, a large number of microvectors (relating to the alignment of the microscanner). In this case, the microscanners can be adjusted in particular electromechanically, with the deflection angles being adjusted in particular via a control unit connected to the array of microscanners or the individual microscanners.

Using the microscanner, an additional angular deflection can be added to each partial beam, which, after the partial beams have passed through the lens array on the second beam path, leads to an offset of the respective focal point of the partial beams in the said plane (meaning the common focal plane between lens array and focusing unit). . Consequently, the angular deflection induced with the microscanners affects the position of the partial beams directed at the workpiece. Accordingly, they can be positioned and/or moved within a predetermined partial beam scanning area.

According to a further embodiment it can be provided that the lens plane of the lens array has the same inclination as the microscanner plane of the array of reflective microscanners, and that the lenses or lens systems in the lens plane are arranged in the same arrangement symmetry, for example a Cartesian arrangement as the microscanners in the microscanner level.

As already mentioned, the respective collimated partial beams propagate again to the lens array along the second beam path following the reflection at the microscanners. Depending on the angular deflection on the reflective array of microscanners, the respective partial beams now have an additional angular deflection compared to a partial beam that is reflected on a microscanner in the basic position. The bundle of collimated partial beams in turn impinges on the lens array. In this case, an essentially collimated partial beam passes through exactly one lens or one lens system of the lens array. Conversely, each lens or each lens system of the lens array is penetrated by exactly one partial beam of the partial beam bundle reflected at the array of microscanners. On the first ray path (i.e. from the ray path from the focusing lens to the lens array) and the second ray path (i.e. from the ray path from the array from microscanners to the lens array), a partial beam thus penetrates the lens array twice with a different, in particular opposite, direction of propagation.

As already mentioned, it can be advantageous within the scope of the invention that the partial beams reflected on the array of microscanners pass through the lens array again on the second beam path, with a respective partial beam on the second beam path passing through a lens of the lens array that is arranged adjacent is to a lens of the lens array, through which the partial beam passes on the first beam path. The partial beams therefore pass through a different lens of the lens array on the first beam path (this can also be referred to as the outward path of the partial beams to the reflective optical functional unit) than on the second beam path (this can also be referred to as the return path of the partial beams from the reflective optical functional unit ). Preferably, the lenses traversed by a single sub-beam on the first and second beam paths are arranged adjacent to one another. Only in this way is it possible to separate the channels into different spatial directions on the outward and return path from the array of microscanners in an otherwise telecentric arrangement. In this context, "adjacent" can be understood to mean an immediately adjacent (lenses are arranged, for example, next to one another or one above the other) arrangement of the lenses, but also an arrangement that is not immediately adjacent (i.e. the lenses are not directly next to one another, one above the other, etc.).

According to a further advantageous embodiment of the invention, it can be provided that the array of microscanners is an array of micromirrors or MEMS mirrors/MEMS scanners, each microscanner being set up to deflect a partial beam impinging on it in two coordinate directions. A coordinate direction can be understood as a direction (e.g. vertical or horizontal) in a plane spanned in space. In the case of an array of micromirrors, it is a DMD arrangement. As is well known, the acronym MEMS stands for micro-electro-mechanical systems. The acronym DMD designates a "digital micromirror device". Both components are known from the prior art, which is why reference is made to general specialist knowledge at this point. MEMS mirrors consist of a single mirror substrate and can be operated either resonantly or quasi-statically. Such mirrors are two-dimensional elements for deflecting radiation. Possible scan frequencies range from 0.1 kHz to 50 kHz. The microscanners (micromirrors or MEMS mirrors) arranged in the array of microscanners can be individually controlled and tilted or moved via the control unit in order to be able to deflect each partial beam individually or apply an additional deflection angle.

According to a further advantageous embodiment, it can be provided that the microscanners are at least partially provided with a dielectric coating. In comparison to a metallic surface, a dielectric coating prevents the microscanner from heating up as a result of residual absorption of the laser radiation impinging on the microscanner. Provision can be made for each microscanner to be completely dielectrically coated, or only partially.

According to a further advantageous embodiment, it can be provided that the partial beams on the second beam path pass through the focusing unit again as a bundle of partial beams, with the partial beam bundle axis before the partial beams impinge on the focusing unit on the second beam path in relation to that along the optical Path running axis of symmetry of the focusing unit is offset and / or tilted.

According to a further advantageous embodiment, a beam selection unit, in particular in the form of an array of aperture stops, can be provided, which is set up to derive, eg reflect or absorb, a predetermined number of partial beams from the optical path, preferably on the second beam path , so that the deflected partial beams do not impinge on the workpiece, wherein the beam selection unit is preferably arranged downstream of the reflective optical functional unit with respect to the beam path. Equally, the aperture stop can also be arranged between the array of microscanners and the lens array. If the beam selection unit is designed in the form of an array of aperture diaphragms, the array of aperture diaphragms is designed in such a way that a partial beam hits the aperture diaphragm for a specific deflection angle of the partial beam set via a microscanner and is absorbed by it, or is reflected in a beam dump . For other deflection angles, the partial beam propagates unhindered through the aperture stop.

The number of partial beams impinging on the workpiece can be set flexibly via the interaction of the reflective optical functional unit and the beam selection unit. This relates not only to the number of partial beams, but also to their spatial selection in relation to a two-dimensional partial beam bundle provided by the beam splitting unit. From the latter, the partial beams can be in any com bination with respect to their position and assigned to the above first or second number of partial beams.

According to a further advantageous embodiment of the invention, it can be provided that the beam selection unit is designed to be reflective, in particular as a micromirror or MEMS mirror. In this case, individual partial beams can be deflected by the respective microscanners in the direction of the reflective beam selection unit. Furthermore, the beam selection unit can be designed in such a way that it comprises a fixed array of mirrors or micromirrors, which direct a predetermined number of partial beams (also a specific partial beam) into a beam dump. At the same time, the array of microscanners or each microscanner can also act as a beam selection unit (by deflecting partial beams from the optical path in the direction of a secondary path). The beam selection unit can also comprise an array of micromirrors or MEMS mirrors. The mirrors arranged in the beam selection unit can be controlled and tilted or moved individually via a control unit in order to be able to deflect each partial beam individually. As already mentioned, a first number of the partial beams can be forwarded or deflected along the optical path in the direction of the workpiece, or removed from the optical path or deflected (the partial beams deflected from the optical path do not impinge on the workpiece) .

According to a further advantageous embodiment, it can be provided that the mirrors arranged in the beam selection unit are at least partially provided with a dielectric coating. Compared to a metallic surface, a dielectric coating prevents the mirror from heating up due to residual absorption of the laser radiation hitting the mirror. Provision can be made for each mirror to be completely dielectrically coated, or only partially.

As already described above, in an alternative embodiment, the beam selection unit can also be designed to be transmissive or absorptive, in particular as at least one blocking element arranged on a chip.

However, such chips are freely available on the market (see for example https://www.preciseley.com/mems-optical-shutter.html). Said blocking element can be moved within a chip plane at least from a first to a second position. In the first position, transmission (that is, passage) of a partial beam impinging on the blocking element is made possible. In the second position, on the other hand, a partial beam impinging on the blocking element is prevented from passing through (absorption). The switching of the blocking element can be controlled via the control unit, and accordingly such a chip (or an array of such chips) is also suitable for use with the present invention. Such a blocking unit can be provided for one or more partial beams and can be arranged between the focusing unit and the lens array or between the lens array and the array of microscanners.

According to a further advantageous embodiment of the invention, it can be provided that a beam-shaping element is arranged between the laser radiation source and the beam splitting unit, which is set up to convert a Gaussian intensity distribution of the laser beam into an intensity distribution that deviates therefrom, in particular into a top-hat intensity distribution or an annular one intensity distribution.

According to a further advantageous embodiment of the invention, it can be provided that the beam splitting unit is set up to split the laser beam into a bundle of partial beams, the partial beams preferably being equidistantly spaced (in angular space). The partial beams can also be divided into a hexagonal bundle by the beam splitting unit, ie the partial beams are arranged in a hexagonal distribution in a cross section. An offset of the partial beams that is provided in this way can be changed by adding an angular deflection via the reflective optical control unit, in particular the array of microscanners. The angular deflection that can be set for each partial beam via the respective microscanner (in particular MEMS mirror) leads to an additional beam offset of a respectively manipulated partial beam on the workpiece, namely to a position shift within the respective partial beam scanning area.

According to a further advantageous embodiment of the invention, a control unit can be provided which is set up to use predefined data to determine a processing path for a rough positioning of the partial beams directed onto the workpiece by positioning the master scanning area at different points on the workpiece, wherein the control unit is connected in terms of control technology to the beam positioning unit.

According to a further advantageous embodiment of the invention it can be provided that the control unit continues to be control-technically connected to the optical control unit, in particular to the Array of microscanners, and the beam selection unit is connected.

1. a. eine erste Anzahl und räumliche Anordnung der auf das Werkstück gerichteten Teilstrahlen zu ermitteln;
2. b. eine zweite Anzahl und räumliche Anordnung der aus dem optischen Pfad abzuleitenden oder zu absorbierenden Teilstrahlen zu ermitteln;
3. c. die Ableitung bzw. Absorption der gemäß Schritt b. ermittelten Anzahl und räumlichen Anordnung von Teilstrahlen zu veranlassen;
4. d. für jeden der auf das Werkstück zu richtenden Teilstrahlen innerhalb des vorgegebenen Teilstrahl-Scanbereichs des jeweiligen Teilstrahls eine Position zu ermitteln und über eine entsprechende Auslenkung des dem jeweiligen Teilstrahl zugeordneten Mikroscanners des Arrays von Mikroscannern einzustellen und/oder für eine vorgegebene Anzahl an Teilstrahlen einen Scanpfad zu ermitteln und eine Scanbewegung der jeweiligen Teilstrahlen durch Ansteuern der den jeweiligen Teilstrahlen zugeordneten Mikroscanner auszuführen.

According to a further advantageous embodiment of the invention, it can be provided that the control unit is set up for the various points of the master scan area on the workpiece

1. a. to determine a first number and spatial arrangement of the partial beams directed onto the workpiece;
2. b. to determine a second number and spatial arrangement of the partial beams to be derived or absorbed from the optical path;
3. c. the derivation or absorption according to step b. determined number and spatial arrangement of partial beams;
4. i.e. to determine a position for each of the partial beams to be directed onto the workpiece within the specified partial beam scanning range of the respective partial beam and to adjust it via a corresponding deflection of the microscanner of the array of microscanners assigned to the respective partial beam and/or to create a scan path for a specified number of partial beams determine and carry out a scanning movement of the respective partial beams by controlling the microscanner assigned to the respective partial beams.

The under the preceding numbers a. and b. The conditions described define the shape of a two-dimensional spot array required for processing at a specific position. The number of partial beams directed onto the workpiece or the laser spots imaged thereon, as well as the spatial arrangement or distribution of the laser spots, depends in particular on the number of processing points on the workpiece or their two-dimensional spatial distribution. For this purpose, the control unit can be set up to control the optical control unit and/or the beam selection unit. Only in this way can the laser processing device according to the under a. to c. described conditions are operated. For example, the control unit can be used to cause a partial beam to be deflected in the direction of a beam selection unit via a microscanner associated with the optical control unit, in particular by adjusting a position of the microscanner. Likewise, the beam selection unit can also be controlled by the control unit in such a way that a partial beam is deflected from the beam path, absorbed or otherwise removed, for example by inserting an aperture or a beam trap into the beam path of a partial beam reflected on the reflective optical functional unit.

According to a further advantageous embodiment of the invention, it can be provided that the control unit is set up to control the beam splitting unit, the reflective optical functional unit and the beam positioning unit. Depending on the processing task and the required number of partial beams to be directed at a certain point on the workpiece, the control unit controls the beam splitting unit, the reflective optical functional unit, in particular each individual microscanner and the beam positioning unit. Alternatively or additionally, the control unit is also able to position and/or move a positioning unit (e.g. an xy table) connected to a workpiece holder.

According to a further embodiment of the invention, focusing optics arranged downstream of the beam positioning unit in relation to the second beam path can be provided, which are set up to focus the partial beams (directed onto the workpiece) to form laser spots on the workpiece. For example, the focusing optics can be designed as a lens, preferably as an F-Theta lens, which is also referred to as a plane field lens. An F-Sin(theta) corrected lens can also be used as focusing optics. In this context, a lens is also to be understood as meaning a complex lens system composed of a plurality of lenses. The laser processing device according to the invention is also suitable for compensating for any distortion errors of the f-theta lens by appropriate positioning of the partial beams.

The laser machining device proposed with the invention can have a laser radiation source with which a pulsed laser beam can be generated. Typical pulse repetition rates are in the range between a few Hertz and a few Megahertz. For high-quality material processing, it has proven to be advantageous if the pulse duration is less than 100 ns, preferably less than 10 ns, in particular less than 1 ns. In this pulse duration range, thermally induced effects predominate during material processing. The pulses can be applied with average powers of more than 10 W, even more than 40 W. Depending on the application, average powers of a few 50 - 500 mW but also average powers of 10-50 W can be present per partial beam.

If pulsed laser radiation with a shorter pulse duration is used, effects that are associated with the deposition of comparably high amounts of energy in a very short time, ie with high peak powers, gain in influence. With these Effects can be, in particular, sublimation effects in which the material of the workpiece abruptly vaporizes locally, ie effects in which material is removed instead of being redistributed. The use of pulsed laser radiation with a pulse duration of less than 100 ps, particularly preferably less than 10 ps and very particularly preferably less than 1 ps has proven to be advantageous here. In particular, pulse durations in the range of a few hundred femtoseconds up to around 10 ps allow targeted material removal by sublimation. Typical pulse repetition rates are between 50 and 2000 Hz. The pulse energies used within the scope of the present invention can be in the range from 5 to 5000 μJ for the laser beam before beam splitting.

Laser radiation sources with even shorter pulse durations that will be available in the future can also be used advantageously in connection with the laser processing device according to the invention or the method according to the invention.

However, the use of pulsed laser radiation with pulse durations even longer than the 100 ns mentioned above can also be useful, for example if certain wavelengths are required for the processing task, or if slower energy deposition is advantageous, for example to achieve targeted local heating to initiate a local processing reaction, which can also be of a chemical nature, such as triggering a polymerization reaction, while at the same time avoiding premature material removal.

Although the present invention is not limited to the use of a laser with a specific wavelength, it is advantageous to use a UV laser as the laser radiation source in repair processes for defects, with the laser radiation source preferably being a laser beam with a wavelength of 355 nm, 343 nm, 266 nm nm or 257 nm generated. In the ablating processing of a workpiece with a laser processing device according to the invention, the wavelength can be selected such that the laser radiation is absorbed by the material to be ablated. Laser radiation with wavelengths in the near infrared and VIS range is less suitable for repair processes unless short pulse durations in the picosecond and femtosecond range are used. The laser radiation source is preferably set up to generate monochromatic laser radiation. Depending on the processing task, however, broadband laser radiation sources can also be advantageous. The use of IR (in particular 1030 nm, 1064 nm) lasers and VIS (515 nm, 532 nm) lasers is advantageous for the application of the laser processing device or the method in laser drilling, which is also covered by the present invention.

According to a further embodiment of the present invention, a mask can be arranged between the beam splitting unit and the focusing unit, which mask is set up to filter out partial beams of a higher or undesired order. The mask can also be provided and set up to filter out non-diffracted portions of the laser radiation.

According to a further advantageous embodiment of the laser processing device according to the invention, the laser processing device can have a quarter-wave delay element. This delay element allows the polarization direction of the generated laser radiation to be adjusted, for example from linear polarization to circular polarization.

With the laser processing device according to the invention or by means of the method according to the invention, an array of processing points (foci) which have an identical z-focus position can be formed on a workpiece to be processed by the partial beams directed onto the workpiece. The positions of the individual processing points (partial beams or the associated laser spots) from the array of processing points have a basic order that is predetermined by the angular distribution of the beam splitting unit. Due to the possibility of individually deflecting each partial beam by means of the array of microscanners, each processing point can be moved or positioned over the workpiece in a certain area (the partial beam scanning area). Due to the principle of the telecentric beam guidance, the partial beam scanning area of each partial beam is always smaller than the distance between two processing points. In contrast to this, the partial beam scan areas can overlap with non-telecentric beam guidance on the workpiece. Furthermore, a specific processing point can be completely hidden by deflecting a partial beam into the beam selection unit. This results in a flexible arrangement of laser spots on the workpiece.

According to a further embodiment of the invention, it can be provided that those components associated with the laser processing device, in particular the beam splitting unit, the focusing unit, the lens array and the array of microscanners, are arranged or designed with regard to their spacing and focal lengths such that a Beam splitting unit present beam splitting level is mapped to the individual microscanner and continue the micro scanner plane is imaged in a common plane, with individual optical channels assigned to the partial beams intersecting at a crossing point in the plane, even if an individually set partial beam direction is changed.

According to a further embodiment of a laser processing device proposed with the invention, it can be provided that the beam positioning unit and/or the focusing optics is/are arranged in such a way that the entrance pupil of the focusing optics is arranged at the crossing point or a crossing region of the partial beams. The place where the partial beams (ideally) converge (point of intersection) is the ideal place to choose the entrance pupil of the focusing optics, especially the F-theta lens. Instead of a defined crossing point, however, the partial beams can also extend over a spatially extending crossing area.

In a further alternative of the invention, it can be advantageous that the optical functional unit comprises a staircase mirror, which is provided instead of or in combination with the focusing unit, the staircase mirror being set up to generate a focal plane tilted to the propagation direction of the partial beams. A bundle of partial beams can be deflected by a stair mirror in the convergent (or divergent) beam path in such a way that the plane of the foci has an angle to the (parallel) direction of propagation. This means that the function of the focusing unit with an offset beam can also be solved using a stair mirror. The distances between the individual foci of the partial beams can be scaled without increasing the spectral error of the partial beams. The structure of the stair mirror is designed in such a way that the individual mirror facets are parallel to one another, but not in one plane. For a telecentric bundle of partial beams, this also allows the bundles to be focused in a plane which has an angle deviating from the perpendicular to the direction of propagation of the bundles. For a two-dimensional arrangement of partial laser beams, two deflections arranged at an angle to one another by the facets of a stair mirror are required for each partial beam.

• 1 eine schematische Darstellung einer mit der erfindungsgemäßen Laserbearbeitungsvorrichtung oder dem erfindungsgemäßen Verfahren bearbeitbaren Werkstückoberfläche mit einer periodischen Anordnung von Bearbeitungsstellen, wobei nur eine vorgegebene Anzahl der Bearbeitungsstellen einer Bearbeitung unterzogen werden sollen (z.B. Fehlstellen oder Bohrungen) sowie einer zweidimensionalen Laserspotanordnung, die mit einer erfindungsgemäßen Laserbearbeitungsvorrichtung auf der Werkstückoberfläche abgebildet werden kann;
• 2 eine schematische Ansicht einer zweidimensionalen Laserspotanordnung, die mit der erfindungsgemäßen Laserbearbeitungsvorrichtung auf der Werkstückoberfläche abgebildet werden kann, wobei dargestellt ist, dass erfindungsgemäß eine beliebige Anzahl von Laserspots in beliebiger räumlicher Anordnung auf dem Werkstück abgebildet werden kann;
• 3 eine schematische Ansicht einer zweidimensionalen Laserspotanordnung, die mit der erfindungsgemäßen Laserbearbeitungsvorrichtung auf der Werkstückoberfläche abgebildet werden kann, wobei dargestellt ist, dass erfindungsgemäß ein jeder Teilstrahl bzw. ein zugehöriger Laserspot innerhalb eines Teilstrahl-Scanbereichs an unterschiedlichen Positionen positioniert werden kann, nämlich an den tatsächlich zu bearbeitenden Stellen;
• 4 eine schematische Ansicht einer zweidimensionalen Laserspotanordnung, die mit der erfindungsgemäßen Laserbearbeitungsvorrichtung auf der Werkstückoberfläche abgebildet werden kann, wobei dargestellt ist, dass die Teilstrahlen bzw. zugehörigen Laserspots simultan und synchron einer gemeinsamen Scanbewegung unterzogen werden;
• 5 eine schematische Ansicht einer zweidimensionalen Laserspotanordnung, die mit der erfindungsgemäßen Laserbearbeitungsvorrichtung auf der Werkstückoberfläche abgebildet werden kann, wobei dargestellt ist, dass die Teilstrahlen bzw. zugehörigen Laserspots einer individuellen Scanbewegung unterzogen werden;
• 6a den schematischen Aufbau einer Laserbearbeitungsvorrichtung gemäß der Erfindung;
• 6b ein Beispiel eines möglichen Strahlverlauf in einer Laserbearbeitungsvorrichtung gemäß 6a;
• 7, 8 eine schematische Ansicht zum Funktionsprinzip jener der Laserbearbeitungsvorrichtung zugehörigen optischen Steuereinheit, insbesondere der Mikroscanner.

Further advantages, configurations and developments, which are related to the laser processing device according to the invention and the method according to the invention, are explained in more detail using an exemplary embodiment described below. This should explain the invention to the person skilled in the art and enable him to carry out the invention, but without restricting the invention. The features described with reference to the exemplary embodiment can also be used to develop the laser processing device according to the invention as well as the method according to the invention. The embodiment is explained in more detail with reference to the figures. There shows:

• 1 a schematic representation of a workpiece surface that can be processed with the laser processing device according to the invention or the method according to the invention, with a periodic arrangement of processing points, with only a predetermined number of processing points being processed (e.g. defects or bores) and a two-dimensional laser spot arrangement, which can be processed with a laser processing device according to the invention the workpiece surface can be imaged;
• 2 a schematic view of a two-dimensional laser spot arrangement that can be imaged with the laser processing device according to the invention on the workpiece surface, showing that according to the invention any number of laser spots can be imaged in any spatial arrangement on the workpiece;
• 3 a schematic view of a two-dimensional laser spot arrangement that can be imaged on the workpiece surface with the laser processing device according to the invention, showing that according to the invention each partial beam or an associated laser spot can be positioned at different positions within a partial beam scanning area, namely at the actually processing bodies;
• 4 a schematic view of a two-dimensional laser spot arrangement that can be imaged with the laser processing device according to the invention on the workpiece surface, it being shown that the partial beams or associated laser spots are subjected to a common scanning movement simultaneously and synchronously;
• 5 a schematic view of a two-dimensional laser spot arrangement that can be imaged with the laser processing device according to the invention on the workpiece surface, it being shown that the partial beams or associated laser spots are subjected to an individual scanning movement;
• 6a the schematic structure of a laser processing device according to the invention;
• 6b an example of a possible beam path in a laser processing device according to FIG 6a ;
• 7 , 8th a schematic view of the functional principle of the optical control unit associated with the laser processing device, in particular the microscanner.

The laser processing device proposed by the invention and the associated method are suitable for simultaneously processing or repairing a plurality of processing points 1 in a workpiece 2 or on an associated surface. In particular, the present invention relates to the repair of displays or display components, for example OLED displays or miniLED displays. The present invention (laser processing device, method) is particularly preferably also suitable for carrying out drilling processes (for example on ceramic materials). On the one hand, static machining processes can be carried out at the mentioned machining points, but on the other hand, scanning machining can also be carried out. The possible uses of the invention mentioned here are not exhaustive.

As already described above, the laser processing device according to the invention and the associated method is particularly suitable for processing processing points 1 of a workpiece 2, for example defects or drilling positions). Before the details of the laser processing device according to the invention are discussed in detail, let the basic principle be the basic processing principle on which the invention is based, generally with reference to FIG 1 until 5 explained.

the 1 1 schematically shows a workpiece 2 to be machined with a (periodic) grid or pattern of a plurality of machining points 1 that can basically be machined. The machining points 1 that can basically be machined can represent a periodic structure of pixels of the workpiece 2, for example. A matrix of possible machining points 1 is shown, of which certain machining points 1 are intended for machining (eg for repairs or for performing a drilling process at the points mentioned). In the present example, three of the processing points 1 or pixels that can basically be processed are marked with a cross, which is intended to represent that a corresponding laser processing is to be carried out at these points. The processing points 1 can have sub-structures (not shown). It is assumed below that the marked processing points 1 have to be processed by laser processing (e.g. repaired or drilled), for example due to local material inhomogeneities, layer thickness deviations or a desired drilling etc.

the 1 also shows a configuration of laser spots 17, or a two-dimensional array of three times three laser spots 17, which are arranged within a master scan area S _M and imaged on the workpiece 2. The master scan area S _M defines an area that is basically accessible to laser processing by projecting the partial beams T onto the workpiece surface, ie without additional positioning of the workpiece 2 relative to the laser processing device or vice versa. However, this does not preclude the partial beams T or laser spots 17 lying within the master scan area S _M together (i.e. the master scan area S _M ) from being positioned in relation to the workpiece 2 or the workpiece 2 in relation to the master scan area S _M or the partial beams T arranged therein (or laser spots 17) can be shifted. This can be done, for example, using a beam positioning unit 9 with which the partial beams T lying within the master scan range S _M can be displaced synchronously and simultaneously on the surface of the workpiece 2 . It is also possible to image only a predetermined number of partial beams T on the workpiece 2 and to move and/or position them synchronously and simultaneously on the surface of the workpiece 2 (this can also be done via a beam positioning unit 9). It should be emphasized that a relative shift of laser spots 17 imaged on the workpiece 2 can also take place by moving or positioning the workpiece 2 relative to statically aligned (or moving) partial beams T.

According to the invention, the laser spots 17 result from a beam splitting of a laser beam L carried out in the laser processing device with a beam splitting unit 5 (see 6 ). One of the core ideas of the invention is to select only those laser spots 17 from the array of laser spots 17 via a corresponding partial beam selection and to image them on the workpiece 2, which are necessary for processing the processing points 1 present, in the example 2 i.e. three laser spots 17. As mentioned, it is also possible to carry out parallel processing at the processing points 1 of a periodic processing pattern with the maximum number of partial beams T or the associated laser spots 17 (the maximum number is defined by the beam splitting unit 5). .

In the example after 1 However, if the three times three laser spots 17 imaged on the workpiece 2 are not on the processing points to be processed (see those marked with a cross recorded processing points 1) addressed. However, as mentioned, the laser processing device is set up to direct only a predetermined number of partial beams T (or associated laser spots 17) of a maximum possible number of partial beams T (or laser spots 17) onto the workpiece 2. In the 2 only those partial beams T (or the associated laser spots 17) are directed onto the workpiece 2 in whose partial beam scanning range S _T the points to be machined (marked with a cross) fall. The partial beam scanning area S _T is that area of a partial beam T in which this or an associated laser spot 17 (independently of the other partial beams T) is individually and flexibly positioned and/or scanned via an optical control unit associated with the laser processing device can. The scan area 20 is in the 1 illustrated schematically with an arrow. With a positioning of the laser spots 17 true to the 2 it would not be possible to process the processing points 1 marked with a cross. Accordingly, the laser spots 17 or partial beams T can be individually positioned within the respective partial beam scanning areas S _T (cf. 3 ), namely in the area of the actual jobs to be processed.

After the positioning of the laser spots 17, the areas to be processed can be processed. However, it is also easily possible to subject the partial beams T or laser spots 17 to a processing movement. In a first variant, this can be done as shown by the arrows in 4 illustrated - run synchronously and simultaneously. Like in the 4 shown, only a predetermined number of the partial beams T or associated laser spots 17 directed onto the workpiece 2 can be subjected to the said movement. Such a synchronous and simultaneous movement of partial beams T or laser spots 17 is preferably provided via a beam positioning unit 9 . Likewise, the workpiece 2 can also be moved relative to static or moving partial beams T. Alternatively, it is also possible to subject the respective partial beams T directed onto the workpiece 2 to an individual processing movement (scanning movement) within the partial beam scanning region S _T . The movement then does not take place synchronously, but individually for each partial beam T. This is illustrated in FIG 5 , in which the different movement paths of the scanning movement of the individual partial beams T or laser spots 17 are indicated with the arrows or sequences of arrows pointing in different directions. As will be explained below, the individual scanning movement is carried out with the optical control unit.

Any configuration of laser spots 17 can therefore be imaged on the workpiece 2 (in adaptation to a pattern of processing points or defects), limited by the maximum number of partial beams T that can be generated via the beam splitting unit 5. Without a beam selection, a beam splitting is predefined Spot array (e.g. a 3 by 3 array) imaged on workpiece 2 ( 1 ).

The method according to the invention and the laser processing device according to the invention are characterized, among other things, by the fact that such processing points 1 can be processed simultaneously in a parallelized processing process, specifically in any spatial configuration. Based on the example of defect repair, the method described with the present invention is cheaper and faster compared to repair techniques based on single-beam laser processing.

As in the 1 until 4 reproduced, the laser processing device proposed with the present invention can project a plurality of partial beams T formed from a laser beam L onto the workpiece 2 to be processed. The number and the spatial arrangement of the partial beams T imaged on the workpiece 2 can be set flexibly. The partial beams T can therefore be switched flexibly, ie only individual partial beams T belonging to the array can be directed onto the workpiece 2 ( 2 ). With the laser processing device according to the invention, it is therefore possible to selectively apply laser radiation (or the laser spots formed by the partial beams T) to the workpiece 2 at specific processing points 1, at which points to be processed (see, for example, the processing points 1 marked with a cross in 2 and 3 ) are trained. In the case of a defect repair, for example, excess material of the workpiece 2 present at these processing points 1 can be ablated by means of laser processing. It is therefore possible to process processing points 1 of the workpiece 2 both within a predetermined master scan range S _M (this means a processing range spanned by the partial beams T projected onto the workpiece 2) and beyond this scan range. The latter is possible in particular by moving the workpiece 2 relative to the stationary laser processing device, alternatively also by moving the master scan area S _M in relation to the workpiece surface (e.g. via a beam positioning unit 9), shown e.g 4 . Also a combination of a relative displacement of the workpiece 2 to the laser processing device and a scanning movement of the master scan region S _M including the partial beams T directed onto the workpiece 2, which is carried out by the laser processing device, in particular a beam positioning unit 9, is possible.

In contrast to the laser processing devices or methods known from the prior art, the laser processing device proposed with the present invention (and the method) is not limited to the imaging of individual rows or columns of an array of partial beams T on the workpiece 2, but can be geometrically arbitrary Combinations of spot arrangements on the workpiece 2 are provided. It is not necessary to specify a specific spatial pattern or a number of partial beams T; instead, any partial beams T of a bundle of partial beams T provided by the beam splitting unit 5 can be selected via the optical control unit (which can also include a beam selection unit 16) and directed in the direction of the workpiece 2 are forwarded.

Another core feature of the invention relates to the individual positioning of each partial beam T in a partial beam scanning area S _T ( 3 , 5 ), wherein the sub-beam scan area S _T includes a smaller lateral extent than the aforementioned master scan area S _M . The master scan range S _M therefore includes a number of partial beam scan ranges S _T corresponding to the number of partial beams T directed onto the workpiece 2 . As below with reference to the description of the structural design of the laser processing device in relation to 5 explained in more detail, an optical control unit can be used to position each of the partial beams T directed onto the workpiece 2 individually at different points within a partial beam scanning range S _T ( 3 ) or move within this range ( 5 ). The individual positioning or movement of each sub-beam T within the respective sub-beam scanning regions S _T takes place independently of the other sub-beams T. Each of the sub-beams T can be controlled individually via the optical control unit. Accordingly, the laser processing device proposed with the invention is suitable not only for processing periodically arranged processing patterns or processing points 1, but also for processing non-periodically or partially periodically arranged processing points 1. In FIG 3 the individual positionability of the laser spots 17 associated with the partial beams T is indicated, with the laser spots 17 not being arranged centered in the partial beam scanning area S _T , but rather in those areas of the points to be processed (processing points 1 marked with a cross). 5 illustrates that the partial beams T directed onto the workpiece 2 or the associated laser spots 17 can also experience an individual scanning movement, which is carried out within the respective partial beam scanning regions S _T . The scanning movements of the individual partial beams T or laser spots 17 can follow different movement paths (represented by the arrow sequences).

In the 6a shows the schematic structure of the laser processing device according to the invention. The representation there is a schematic illustration. In the 6b However, the specific beam path is reproduced in detail using an exemplary example, namely for a beam splitting of a laser beam L generated by a laser radiation source 3 into three partial beams T, which in turn each comprise three sub-partial beams Ts. The sub-beams Ts (shown only for one of the sub-beams T) are focused on the workpiece 2 onto a laser spot, which is why in the present description under a sub-beam T or a laser spot associated with the sub-beam T, it must be taken into account that the beam path is refers to a number of sub-beams Ts. In the 6b the detailed course of the partial beams T or sub-partial beams Ts, starting from a beam splitting unit 5 to a beam positioning unit 9, is reproduced.

For processing a workpiece 2 with a laser processing device according to the invention, the workpiece 2 is arranged in a workpiece holder, not shown. The workpiece holder can be designed in the form of an xy table that can be moved in a horizontal plane.

Like in the 6a shown, the laser processing device initially comprises a laser radiation source 3 with which a laser beam L is generated and emitted along an optical path 4 in the direction of the workpiece 2, in particular in the form of laser pulses. A beam splitting unit 5 is arranged downstream of the laser radiation source 3 in the beam direction. The beam splitting unit 5 is set up to split the laser beam L into a multiplicity of partial beams T. The beam splitting unit 5 can be a—per se known—diffractive optical element (DOE) or an SLM. The number of partial beams T can already be preset with the beam splitting unit 5 . A rough setting of the distances between the laser spots of the partial beams T in a plane of the workpiece 2 can already be set with the beam splitting unit 5 . The beam splitting unit 5 can be used to split a laser beam L into partial beams T, which provide a two-dimensional spatial pattern of laser spots 17 on the workpiece 2 . Like in the 6b recognizable, each partial beam T comprises a number (here three) of sub-beams Ts, which, however, can be collectively referred to as sub-beams T or main beams Hs. In the 6a only the course of the main rays Hs is shown.

Starting from the laser radiation source 3 , a collimated laser beam L impinges on the beam splitting unit 5 . The beam splitting unit 5 splits the laser beam into a bundle of identical partial beams T, each of which has a defined angle to one another.

A beam shaping element (not shown) can be provided between the laser radiation source 3 and the beam splitting unit 5, with which a large number of partial beams T with a predetermined intensity distribution can be generated on the workpiece from a laser beam L with a Gaussian intensity distribution, in combination with the beam splitting unit 5 , for example a top-hat intensity distribution or a ring-shaped intensity distribution.

The in the 6a and 6b The laser processing device shown has an optical functional unit 7 which is arranged between the beam splitting unit 5 and a reflective optical functional unit 8 . In this case, the optical functional unit 7 (this can - but does not have to - be designed to be transmissive, for example) and a group of optical functional elements 10, 12 arranged one behind the other arranged lenses or lens systems) and a lens array 11 of lenses 12 arranged at a distance from the focusing unit 10. The lens array 11 always has one “row” or “column” of lenses 12 more in relation to the number of microscanners 15 in the array 14.

A transmissive optical functional unit 7 is to be understood within the meaning of the invention that the partial beams T pass through the components belonging to the transmissive optical functional unit (the focusing unit 10 and the lens array 11). On the other hand, the partial beams T are reflected at the reflective optical functional unit 8 .

The partial beams T associated with the bundle of partial beams T pass on a first beam path through the focusing unit 10 and the lens array 11 until they are reflected at the reflective optical functional unit 8 (see, for example, the propagation of the lower partial beam T _H in 6a or the upper partial beam T together with sub-partial beams Ts in 6b) . After the partial beams T have been reflected at the reflective optical functional unit 8, at least some of the partial beams T reflected there pass through the optical functional unit 7 again on a second beam path, in particular the lens array 11 and the focusing unit 10. Following the beam splitting in the beam splitting unit 5, the partial beams T accordingly propagate as a bundle of collimated partial beams T in the direction of the focusing unit 10. The partial beams T are collimated and focused by the focusing unit 10.

As, for example, based on the course of the partial beam T _H in 6a or the partial rays T in 6b can be seen, on the first beam path, each partial beam T of the bundle of partial beams T passes through a lens 12 of the lens array 11 assigned to the respective partial beam T. The sub-partial beams Ts of a respective partial beam T also pass through a common lens 12 ( 6b) . On the second beam path, at least part of the partial beams T reflected on the reflective optical functional unit 8 again passes through a lens 12 of the lens array 11 assigned to the respective partial beam T. Depending on the number of partial beams T to be imaged onto the workpiece 2, some of the reflected partial beams T can be deflected by the reflective optical control unit 8 in the direction of a beam selection unit 16, as a result of which the partial beam T is removed from the beam path or absorbed. It can therefore be provided that not all of the partial beams T that have passed through the focusing unit 10 and the lens array 11 on the first beam path arrive in the direction of the workpiece 2, but instead are deflected or diverted from the beam path beforehand (preferably on the second beam path) by suitable means . A partial beam T can be removed or deflected from the beam path either via a beam selection unit 16 provided specifically for this purpose (this can deflect a partial beam T from the beam path, e.g. in the direction of a beam trap), or a partial beam T is detected by the reflective optical functional unit 8 directed in the direction of a beam selection unit 16 or a beam trap. As a result, a corresponding number of partial beams T required for processing at a given position of the master scan region S _M on the workpiece 2 can be deflected or removed from the beam path of the partial beams T or removed.

As the 6a and 6b can also be seen, the focusing unit 10 is arranged in such a way that a partial beam bundle axis _{AB is offset before the partial beams T impinge on the focusing unit 10 on the first beam path in relation to an axis of symmetry A F of} the focusing unit 10 running along the optical path 4 is. The offset of the bundle of partial beams T or the part beam axis AB to the axis of symmetry A _F of the focusing unit 10 causes the partial beam axis _{AB to run at an angle to the axis of symmetry A F of the} focusing unit 10 after passing through the focusing unit 10, impressively shown in 6b .

It can also be seen that the bundle of partial beams T has a telecentric beam path after passing through the focusing unit 10 on the first beam path. This can be seen particularly well in the detailed representation of the 6b . As shown there, the sub-beams T (a bundle of three sub-beams T is shown here as an example) each consist of a bundle of a predetermined number of sub-beams Ts (shown for the upper sub-beam T). A telecentric beam path means that the sub-partial beams Ts can each be described by a main beam Hs, with the main beams Hs being parallel to one another after passing through the focusing unit 10 . The main beams Hs are composed of sub-beams Ts.

The partial beams T of the bundle of partial beams T are focused on the first beam path in a plane E arranged perpendicular to the optical path 4 or to the axis of symmetry A _F of the focusing unit 10, the plane E preferably being arranged between the focusing unit 10 and the lens array 11. It can also be advantageous on the second beam path to focus the partial beams T of the bundle of partial beams T after passing through the lens array 11 in the said plane E.

The lens array 11 comprises a lateral (two-dimensional) arrangement of lenses or lens systems 12, which are arranged in a common lens plane 19, the lens plane 19 being arranged perpendicular to the optical path 4 or to the axis of symmetry A _F of the focusing unit 10. The lenses 12 of the lens array 11 are arranged in such a way that each partial beam T (including sub-partial beams Ts) of the bundle of partial beams T passes through a lens 12 in each case. Such an arrangement enables the partial beams to be separated into separate optical channels. Each partial beam T passing through the lens array 11 or the individual lenses 12 is collimated by the respective lens 12 of the lens array 11 . The distance between the focusing unit 10 and the lens array 11 is selected such that the partial beams T are essentially collimated after passing through the lens array 11 . After the partial beams T have passed through the lens array 11, the partial beams T propagate in the respective optical channels on the first beam path until they strike the reflective optical functional unit 8. Overall, the distances and focal lengths of the optical components are selected such that a beam splitting plane in the beam splitting unit is imaged on the individual microscanners 15 and the microscanners 15 are also imaged in a common plane. This is done by combining the focusing unit 10 and the lens array 11. The second image mentioned means that the individual optical channels intersect in one plane—even if an individually set partial beam direction changes.

The reflective optical functional unit 8 is formed from an array 14 of reflective microscanners 15. The array 14 of reflective microscanners is preferably formed in a lateral two-dimensional arrangement of reflective microscanners 15, with the microscanners 15 being arranged in a common microscanner plane 36 . The microscanner plane 36 runs perpendicularly to the optical path 4 or to the axis of symmetry A _F of the focusing unit 10. The reflective microscanners 15 are arranged in such a way that one partial beam T (or the associated sub-partial beams Ts) from each microscanner 15 is reflected. The angle of incidence α of each partial beam T on the respective reflective microscanner 15 corresponds approximately to the above-mentioned angle between the partial beam bundle axis _AB and the axis of symmetry _AF of the focusing unit 10. Accordingly, the number of reflective microscanners 15 corresponds to the number along the first Partial beams T running along the beam path. After a respective partial beam T impinges on a reflective microscanner 15, the partial beam T is reflected on this microscanner 15.

As in particular in the 7 and 8th illustrated, with a respective microscanner 15 a partial beam T incident on the microscanner can be compared to a simple reflection according to the principle of angle of incidence α=angle of emergence β ( 7 ) an additional angular contribution x must be added ( 8th ). This can be done by tilting the microscanner 15 from a basic position. Like in the 8th shown, the microscanner 15 can be tilted with its microscanner axis 36 relative to a microscanner plane 18 . The additional angle addition ultimately enables an additional offset of the laser spots 17 imaged on the workpiece 2 and the ability to position or move the laser spots 17 within the respective partial beam scanning regions S _T .

A deflection angle of the partial beams T can thus be set flexibly with the respective microscanners 15 . The microscanners are preferably set mechanically, with the deflection angles being set using an array 14 of microscanners 15 or the individual microscan nern 15 connected control unit (not shown) takes place.

After the partial beams T have again passed through the lens array 11 on the second beam path, the aforementioned angle addition leads to a lateral offset of the respective focus point of the partial beams T in the plane E. Consequently, the angular deflection induced with the microscanners 15 affects the position of the Workpiece 2 directed sub-beams T from. In this case, the plane E (this can also be referred to as the intermediate focal plane) is imaged in the processing plane of a lens associated with the beam positioning unit 9 .

Following the reflection at the microscanners 15, the respective collimated partial beams T propagate again along the second beam path to the lens array 11. The partial beams T now have - depending on the angular deflection at the reflective array 14 of microscanners 15 - an additional angular deflection compared to a partial beam T of the on a microscanner 15 in the basic position (according to 7 ) is reflected. The bundle of collimated partial beams T in turn impinges on the lens array 11 . A substantially collimated partial beam T passes through exactly one lens 12 of the lens array 11. Conversely, each lens 12 of the lens array 11 is penetrated by exactly one partial beam T of the partial beam bundle reflected on the array 14 of microscanners 15. On the first beam path (ie from the beam path from the focusing lens 10 to the lens array 11) and the second beam path (ie from the beam path from the array 14 of microscanners 15 to the lens array 11), a partial beam T thus penetrates the lens array 11 twice with a different, in particular opposite direction of propagation.

As in the 6a and 6b illustrated, a partial beam T _R (including sub-partial beams Ts, see 6b ) through a lens 12' of the lens array 11, which is arranged adjacent to a lens 12 of the lens array 11, through which the partial beam T _H passes on the first beam path. The partial beams T therefore pass through a different lens 12 of the lens array 11 on the first beam path (this can also be referred to as the outward path of the partial beams T to the reflective optical functional unit 8) than on the second beam path (this can also be referred to as the return path of the partial beams T from of the reflective optical functional unit 8). The lenses 12, 12′ through which a single partial beam T passes on the first and second beam path are preferably—but not necessarily—arranged adjacently. This is the only way in which, in an otherwise telecentric arrangement, is it possible for the channels to be separated (which is to be understood here as a separation in solid angle directions) on the outward and return path from the array 14 of microscanners 15 .

As already mentioned, and in the 6a and 6b shown, the partial beams T on the second beam path pass through the focusing unit 10 again as a bundle of partial beams T, with the partial beam bundle axis _AB before the partial beams T impinge on the focusing unit 10 on the second beam path in relation to that along the optical Path 4 running axis of symmetry A _F of the focusing unit is offset. It should be emphasized at this point that the focusing unit 10 converges the partial beams T of the partial beam bundle passing through the focusing unit 10 on the second beam path, i.e. the optical axes of the partial beams T converge (in the case of the telecentric beam path mentioned at the outset, the partial beams even meet at one space point). However, the symmetry of the arrangement of the partial beams about the common partial beam bundle axis _AB is broken in the general case, since each partial beam can have a different angle (due to the individual angle addition by the reflective optical functional unit 8). The focusing unit 10 preferably collimates each partial beam T passing through the focusing unit 10 .

According to the embodiment 6a and 6b The laser processing device shown also includes a beam positioning unit 9, in particular in the form of a galvanometer scanner, which is set up to carry out a rough positioning of the partial beams T directed onto the workpiece 2 relative to the workpiece 2, namely by positioning a master scan region including the partial beam scan regions S _T S _M relative to the workpiece 2. At the respective positions of the master scan areas S _M (and thus the partial beams T) set via the coarse positioning, an individual fine positioning of the partial beams T within predetermined partial beam scan areas S _T of the respective Partial beams T take place. The beam positioning unit 9 is therefore used to deliver all partial beams T directed onto the workpiece 2.

With the beam positioning unit 9, the partial beams T directed onto the workpiece 2 can be moved over the workpiece 2, preferably synchronously and simultaneously, namely by moving the master scan region S _M enclosing the partial beam scan regions S _T relative to the workpiece 2.

The beam positioning unit 9 is arranged downstream of the optical control unit 6 in relation to the beam direction or the beam path, the beam path of the partial beams T is therefore to that effect designed such that the partial beams T impinge on the beam positioning unit 9 only after the reflection at the reflective optical control unit 6 . As mentioned several times, individual scanning programs or scanning movements can also be executed for the individual partial beams T or laser spots 17 imaged on the workpiece 2 .

In relation to the second beam path, focusing optics 13 are arranged downstream of the beam positioning unit, with which the partial beams T (directed onto the workpiece 2) are focused, forming laser spots 17 on the workpiece 2. For example, the focusing optics 13 can be designed as a lens, preferably as an F-Theta lens, which is also referred to as a plane field lens.

Reference List

1

processing point

2

workpiece

3

laser radiation source

4

optical path

5

beam splitting unit

7

optical functional unit

8th

reflective optical functional unit

9

beam positioning unit

10

focusing unit

11

lens array

12

lens

13

Focusing optics, F-theta lens

14

array

15

microscanner

16

beam selection unit

17

laser spot

18

microscanner level

19

lens plane

20

scan area

36

microscanner axis

40

workpiece holder

L

laser beam

T

partial beam

th

partial beam

TR

partial beam

ts

sub beam

AWAY

sub-beam axis

AF

axis of symmetry

E

level

HS

main beam

ST

Partial beam scan area

SM

master scan area

a

angle of incidence

β

drop angle

x

additional angle

Claims (41)

Laser processing device for processing predetermined processing points (1) of a workpiece (2), comprising a. a laser radiation source (3) which is set up to generate a laser beam (L) and to emit it along an optical path (4) in the direction of the workpiece (2); b. a beam splitting unit (5) which is arranged downstream of the laser radiation source (3) in the beam direction and is set up to split the laser beam (L) into a bundle of partial beams (T); c. an optical control unit downstream of the beam splitting unit (5) in the beam direction, comprising a reflective optical functional unit (8) formed from an array (14) of reflective microscanners (15), wherein the optical control unit is set up to, • from the bundle of partial beams (T ) to select any number of partial beams in any spatial combination and to direct them onto the workpiece (2), • at least one, preferably each, of the partial beams (T) directed onto the workpiece (2) using a partial beam (T ) assigned microscanners (15) of the array (14) of microscanners (15) within a predetermined partial beam scanning range (S _T ) of the respective partial beam (T) to be positioned and/or moved, characterized in that the laser processing device has an optical functional unit (7 ) comprises, which is arranged between the beam splitting unit (5) and the reflective optical functional unit (8). t, wherein the optical functional unit (7) comprises a lens array (11) of lenses (12), wherein the bundle of partial beams (T) associated partial beams (T) on a first beam path up to reflection at the reflective optical functional unit (8) pass through the lens array (11), and after being reflected at the reflective optical functional unit (8), at least some of the partial beams (T) reflected there again pass through the lens array (11) on a second beam path, namely in such a way that a respective partial beam (T) on the second ray path passes through a lens (12) of the lens array (11) which is arranged adjacent to a lens (12) of the lens array (11) through which the partial beam (T) passes on the first beam path. Laser processing device claim 1 , characterized by a beam positioning unit (9) in the form of a galvanometer scanner, a pivot scanner or a two-axis single-mirror scanner, which is set up to roughly position the partial beams (T) directed onto the workpiece (2) relative to the workpiece (2) to be carried out, namely by positioning a master scan region (S _M ), which includes the partial beam scan regions (S _T ), relative to the workpiece (2) and/or is set up to project the partial beams (T) directed onto the workpiece (2) over the To move the workpiece (2), namely synchronously and simultaneously, namely by moving the sub-beam scan areas (S _T ) enclosing the master scan area (S _M ) relative to the workpiece (2). Laser processing device according to one of the preceding claims, characterized by a laser processing device designed to that effect, in which on the first beam path each partial beam (T) of the bundle of partial beams (T) passes through a lens (12) of the lens array (11 ) and on the second beam path at least part of the partial beams (T) reflected on the reflective optical functional unit (8) passes through a lens (12) of the lens array (11) assigned to the respective partial beam (T). Laser processing device according to one of the preceding claims, characterized by a laser processing device designed to that effect, in which on the first beam path each partial beam (T) of the bundle of partial beams (T) passes through the focusing unit (10) and on the second beam path at least part of the the partial beams (T) reflected by the reflective optical functional unit (8) again passes through the focusing unit (10). Laser processing device according to one of the preceding claims, characterized by a beam selection unit (16) in the form of an array (30) of aperture stops, which is set up to deflect a predetermined number of partial beams (T) on the second beam path from the optical path (4). or to absorb, so that the deflected partial beams (T) do not impinge on the workpiece (2), wherein the beam selection unit (16) is preferably arranged downstream of the reflective optical functional unit (8) with respect to the beam path. Laser processing device claim 5 , characterized in that the beam selection unit (16) is reflective, namely as a micro mirror or MEMS mirror. Laser processing device claim 5 , characterized in that the beam selection unit (16) is absorptive. Laser processing device according to one of the preceding claims, characterized in that the bundle of the plurality of partial beams (T) before and after passing through the focusing unit (10) on the first beam path has a partial beam bundle axis (A _B ) in relation to which the A plurality of partial beams (T) are arranged symmetrically. Laser processing device according to one of the preceding claims, characterized in that the focusing unit (10) is arranged such that the partial beam bundle axis (A _B ) before the impingement of the partial beams (T) on the focusing unit (10) on the first beam path in relation to an axis of symmetry (A _F ) of the focusing unit (10) running along the optical path (4). Laser processing device according to one of the preceding claims, characterized in that the focusing unit (10) is arranged in such a way that the bundle of partial beams (T) has a telecentric beam path before and/or after passing through the focusing unit (10) on the first beam path. Laser processing device according to one of the preceding claims , characterized in that the optical partial beam bundle axis (A _B ) after the partial beams (T) have passed through the focusing unit (10) on the first beam path at an angle to the axis of symmetry (A _F ) of the focusing unit (10) runs. Laser processing device according to one of the preceding claims, characterized in that the partial beams (T) of the bundle of partial beams (T) on the first beam path are arranged in a plane perpendicular to the optical path (4) or to the axis of symmetry (A _F ) of the focusing unit (10). (E) are focused, the plane (E) being arranged between the focusing unit (10) and the lens array (11). Laser processing device according to one of the preceding claims, characterized in that the lens array (11) comprises a lateral arrangement of lenses (12) or lens systems which are arranged in a common lens plane (19), the lens plane (19) is arranged perpendicular to the optical path (4) or to the axis of symmetry ( _AF ) of the focusing unit (10). Laser processing device according to one of the preceding claims, characterized in that the array (14) of reflective micro-scanners (15) comprises a lateral arrangement of reflective micro-scanners (15) which are arranged in a common micro-scanner plane (18), the micro-scanner Level (18) is arranged perpendicular to the optical path (4) or to the axis of symmetry (A _F ) of the focusing unit (10). Laser processing device according to one of the preceding claims, characterized in that the lens plane (19) of the lens array (11) has the same inclination as the microscanner plane (18) of the array (14) of reflective microscanners (15), and that the lenses ( 12) or lens systems in the lens plane (19) are arranged in the same arrangement symmetry as the microscanners (15) in the microscanner plane (18). Laser processing device according to one of the preceding claims, characterized in that a respective partial beam (T) is reflected by a respective microscanner (14). Laser processing device according to one of the preceding claims, characterized in that each microscanner (14) is set up to assume a basic position and at least one first deflection position, a microscanner (14) located in the first deflection position being set up to place a beam on the microscanner ( 14) to deflect the incident partial beam (T) in the direction of the second beam path. Laser processing device according to one of the preceding claims, characterized in that each microscanner (14) is set up to assume a second deflection position, a microscanner (14) located in the second deflection position being set up to project a partial beam impinging on the microscanner (14). (T) from the optical path (4) deflect. Laser processing device according to one of the preceding claims, characterized in that a deflection angle can be set flexibly and dynamically with the respective microscanners (14) for the respective partial beam (T) impinging on the microscanner (14). Laser processing device according to one of the preceding claims, characterized in that the array (13) of micro-scanners (14) is an array of micro-mirrors or MEMS mirrors / MEMS scanners, each micro-scanner (14) being set up to impinge thereon a partial beam (T) in two coordinate directions. Laser processing device according to one of the preceding claims, characterized in that the partial beams (T) on the second beam path as a bundle of partial beams (T) again pass through the focusing unit (10), the partial beam bundle axis (A _B ) before the partial beams impinge (T) on the focusing unit (10) on the second beam path in relation to the axis of symmetry (A _F ) of the focusing unit (10) running along the optical path (4) and/or is tilted. Laser processing device according to one of the preceding claims, characterized in that the beam splitting unit (5) is a diffractive optical element. Laser processing device according to one of the preceding claims, characterized in that between the laser radiation source (3) and the beam splitting unit (5) a beam shaping element is arranged, which is set up to convert a Gaussian intensity distribution of the laser beam (L) into a different intensity distribution, namely in a top-hat intensity distribution or a ring-shaped intensity distribution. Laser processing device according to one of the preceding claims, characterized in that the beam splitting unit (5) is set up to split the laser beam (L) into a bundle of partial beams (T), the partial beams (T) being equidistantly spaced. Laser processing device according to one of the preceding claims, characterized by a control unit which is set up to use predetermined data to define a processing path for a rough positioning of the partial beams (T) directed onto the workpiece (2) by positioning the master scan region (S _M ) to be determined at various points on the workpiece, the control unit being connected to the beam positioning unit in terms of control technology. Laser processing device according to one of the preceding claims, characterized in that the control unit is also connected in terms of control technology to the optical control unit, namely to the array (13) of microscanners (14) and the beam selection unit (15). Laser processing device according to one of the preceding _claims , characterized in that the control unit is set up to a. to determine a first number and spatial arrangement of the partial beams (T) directed onto the workpiece (2), b. to determine a second number and spatial arrangement of the partial beams (T) to be derived or absorbed from the optical path (4), c. the derivation and/or absorption of the according to step b. determined number and spatial arrangement of partial beams (T); i.e. to determine a position for each of the partial beams (T) to be directed onto the workpiece (2) within the specified partial beam scanning range (S _T ) of the respective partial beam (T) and via a corresponding deflection of the microscanner ( 14) of the array of microscanners (14) and/or to determine a scan path for a predetermined number of partial beams (T) and to carry out a scanning movement of the respective partial beams (T) by controlling the microscanners (15) assigned to the respective partial beams (T). . Laser processing device according to one of the preceding claims, characterized in that the control unit is set up to control the beam splitting unit (5), the reflective optical functional unit (8) and the beam positioning unit (9). Laser processing device according to one of the preceding claims, characterized by focusing optics (13) which are arranged downstream of the beam positioning unit (9) in relation to the second beam path and are designed to focus the partial beams (T) onto the workpiece (2). Laser processing device claim 29 , characterized in that the focusing optics (13) is an F-Theta lens or an F-Sin-theta corrected lens. Laser processing device according to one of the preceding claims, characterized in that those components associated with the laser processing device, namely the beam splitting unit (5), the focusing unit (10), the lens array (11) and the array (14) of microscanners (15), with respect to their spacing and focal lengths are arranged and designed in such a way that a beam splitting plane present in the beam splitting unit (5) is imaged onto the individual microscanners (15) and the microscanner plane (18) is also imaged in a common plane, with individual, den Intersect optical channels assigned to partial beams (T) - even when changing an individually set partial beam direction - at a crossing point in the plane. Laser processing device Claim 31 , characterized in that the beam positioning unit (9) and/or the focusing optics (13) is/are arranged such that the entrance pupil of the focusing optics (13) is arranged at the crossing point or a crossing area of the partial beams (T). Laser processing device according to one of the preceding claims, characterized in that the optical functional unit (7) comprises a staircase mirror which is provided instead of or in combination with the focusing unit (10), the staircase mirror being set up to have a direction of propagation of the partial beams (T) to generate a tilted focal plane. Method for laser processing a workpiece (2) at predetermined processing points (1) using a laser processing device according to patent claim 1 , wherein after generating a laser beam (L) with a laser radiation source (3), a beam splitting of the laser beam (L) into a bundle of partial beams (T) is carried out and at a predetermined number of points using an optical control unit (6) a predetermined number of sub-beams (T) of the bundle of sub-beams (T) is directed onto the workpiece (2) in any spatial combination, and wherein the sub-beams (T) directed onto the workpiece (2) are positioned within a predetermined sub-beam scanning range (S _T ). and/or be moved. procedure after Claim 34 , characterized in that prior to the positioning of the partial beams (T) in the respective partial beam scanning areas (S _T ), a rough positioning of the partial beams (T) directed onto the workpiece (2) is carried out at a predetermined number of points, namely by arranging the workpiece (2) in a workpiece holder (40) and a. Positioning the workpiece (2) relative to the laser processing device, or b. Positioning the partial beams (T) directed towards the workpiece (2) and lying within a master scan area (S _M ) relative to the workpiece (2) using a beam positioning unit (9), or c. Positioning of the workpiece (2) relative to the laser processing device and the partial beams (T) directed towards the workpiece (2) and lying within a master scan area (S _M ) with a beam positioning unit (9). procedure after Claim 34 or 35 , characterized in that using the optical control unit following the rough positioning and the positioning of the partial beams (T) directed onto the workpiece (2) within the predetermined partial beam scanning range (S _T ) for a predetermined number of the partial beams aimed at the workpiece (2 ) directed partial beams (T) an individual scanning movement is carried out. Procedure according to one of Claims 34 until 36 , characterized in that using the beam positioning unit (9) following the rough positioning and the positioning of the partial beams (T) directed onto the workpiece (2) within the predetermined partial beam scanning range (S _T ) for the onto the workpiece (2) directed partial beams (T) a simultaneous and synchronous scanning movement is carried out. Procedure according to one of Claims 34 until 37 , characterized in that using the optical control unit and / or the beam positioning unit following the coarse positioning and optionally the positioning of the part beams t directed on the workpiece (2), within the predetermined partial beam scan area (S _t ) for a predetermined number of the workpiece (2) directed partial beams (T) a positioning correction of positioning errors, namely resulting from distortion errors of an optical functional element, is carried out, namely using a correction matrix. procedure after Claim 38 , characterized in that the correction matrix is determined using an optical measuring system, namely a measuring system arranged in the focus of a T-theta lens. Procedure according to one of Claims 34 until 39 , characterized in that using the beam positioning unit (9) following the rough positioning and the positioning of the partial beams (T) directed onto the workpiece (2) within the predetermined partial beam scanning range (S _T ) for the onto the workpiece (2) directed partial beams (T), a simultaneous and synchronous scanning movement is carried out along a predetermined scanning path, with the execution of the scanning movement using the optical control unit, namely the reflective microscanner (15), for a predetermined number of the partial beams directed onto the workpiece (2) (T ) a dynamic positioning correction of positioning errors, namely resulting from distortion errors of an optical functional element, is carried out, namely using a correction matrix. Procedure according to one of Claims 34 until 40 , characterized in that the method using a laser processing device according to one of claims 2 until 33 is performed.

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