WO2020239846A1

WO2020239846A1 - Laser machining apparatus and method for simultaneously and selectively machining a plurality of machining points of a workpiece

Info

Publication number: WO2020239846A1
Application number: PCT/EP2020/064722
Authority: WO
Inventors: Stephan Eifel; Jens Holtkamp; Joachim Ryll
Original assignee: Pulsar Photonics Gmbh
Priority date: 2019-05-27
Filing date: 2020-05-27
Publication date: 2020-12-03
Also published as: DE102019114191A1

Abstract

The present invention relates to a laser machining apparatus and a method for the machining of machining points of a workpiece. The laser machining apparatus comprises: a. a laser radiation source (3), which is configured to generate a laser beam (10) and emit same 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 which is configured to split the laser beam (10) into a plurality of partial beams (T) which are distributed in a predefined spatial pattern; c. a beam selection unit (6), which is arranged downstream of the beam splitting unit (5) in the beam direction and which is configured ° to forward a first number (A1) of the partial beams (T) along the optical path (4) in the direction of the workpiece (2), ° to deflect a second number (A2) of the partial beams (T) out of the optical path (4), the beam selection unit (6) further being configured to select partial beams (T) in any spatial combination from the spatial pattern of the partial beams (T) and allocate them to the first number (A1) and to the second number (A2); d. a beam positioning unit (9), which is arranged downstream of the beam selection unit (6) in the beam direction and which is configured to map, on the workpiece (2), laser spots (18) corresponding to the first number (A1) of partial beams (T), and is further configured to simultaneously and synchronously move the laser spots (18) over the workpiece optionally for positioning and/or machining. Said laser machining apparatus and the method described in the invention for machining a workpiece enable several machining points to be machined quickly and in parallel.

Description

Laser processing device and method for the simultaneous and selective processing of a plurality of processing points of a

Workpiece

The present invention relates to a laser processing device and a method for processing processing points on a workpiece. The processing points can, for example, be defects in a workpiece that 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 by the invention or the method proposed by the invention for processing a workpiece by way of a "Laser Induced Forward Transfer" (LIFT for short) processes can be used, ie for processing predetermined processing points on a workpiece.

During the production of graphic displays such as displays, OLED (organic light emitting diode) displays or mini LED displays, for example, production-related defects can occur. Such flaws are to be understood in the context of the terminology used here as "processing points". These flaws can occur at certain pixels of the display, for example in the electrical contacting An organic light-emitting diode (OLED) is a luminous thin-film component made of organic semiconducting materials, which differs from so-called inorganic light-emitting diodes (LED) in that the electrical current and luminance is lower and there are no single crystals Materials are required. Displays based on OLEDs are installed in smartphones, tablet computers, televisions or computer monitors, among other things. The present invention can be used both for processing OLED displays and for processing LED displays (eg ni LED displays) can be used.

Since such defects are usually not distributed homogeneously on the display surface and often occur on a large number of display pixels, it is It is desirable to subject the defects to a repair or correction process which, on the one hand, enables several defects to be processed simultaneously and, on the other hand, can be flexibly adapted to a distribution of defects on a specific display. Laser processing techniques are particularly suitable for such correction of defects, because with such a pixel-by-pixel, high-resolution and, at the same time, fast (erosive) processing is guaranteed. To process such defects with individual laser beams is generally known from the prior art, but associated with disadvantages in procedural management and process duration. Correspondingly, methods that allow several defects to be processed in parallel are of particular interest. From US Pat. No. 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; in principle, any workpieces or materials with defects can be processed with the laser processing device according to the invention or with the associated method Allow ablative processing. The processed material must therefore be ablatable by laser radiation. Furthermore, the present invention is suitable for use in the LIFT method already mentioned above. Pulsed laser beams (eg 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 substrates. Correspondingly, in the context of the invention, the "processing points" can also be understood as those points on a first substrate (a workpiece in the sense of the invention) at which a material transfer by way of the LIFT method to a second (for example co-planar to the first Substrate) arranged substrate is to take place, in particular around those points of a first substrate (workpiece) that are to be irradiated with laser beams.Depending on the requirements of the workpiece to be processed, a predetermined processing point or pixels of a workpiece can be defined using the LIFT method Processing patterns (transfer pattern) are formed in the context of the present invention Partial beams of a split laser beam can be directed in point-and-shoot mode to given processing points on a workpiece.

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

When processing materials with laser radiation (for example 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, optimizations of the laser process by changing the intensity distribution in the processing plane are increasingly being investigated. 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 optimization potential for laser process development. The resulting advantages of beam shaping are, for example, higher process speeds or better processing results.

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. Using suitable beam shaping techniques, however, laser beams can be shaped while changing the intensity distribution. In order to form an intensity distribution of a laser beam, either its phase, its amplitude or both quantities can be modulated together. Phase modulators, amplitude modulators or phase and amplitude modulators are used accordingly, for example in the form of diffractive beam shapers. Diffractive beam formers (Diffractive Optical Elements, DOE for short) for setting far-field intensities can be produced as phase elements in glass or other transparent materials. Furthermore, the form of an intensity distribution can take place by refraction and reflection on optical elements. Correspondingly shaped refractive or reflective elements such as, for example, deformed or deformable mirrors or transmissive elements with a geometrical 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. The totality of the partial beams forms a new intensity distribution after being formed by the element. An example of such a beam shaping is the reshaping of a Gaussian laser beam into a top hat-shaped laser beam, also called a Gauss-to-top hat beam shaper. Such a beam shaper can also be used in the laser processing device according to the invention. The geometrical deformation of the surface necessary for beam shaping can be calculated with analytical, numerical or iterative methods (eg superposition of Zernike polynomials).

Diffractive beam-shaping elements can, however, also be designed as beam splitters (within the scope of the present invention, the function of the DOE as a beam splitter is decisive). Binary grids or blazed gratings may be mentioned as examples in this context. Due to the geometry of the diffractive structure, constructive interference occurs on a rectangular grid in the spatial frequency space (k-space). A wide variety of arrangements of active diffraction orders (constructive interference) can be implemented using numerical algorithms. The angular separation of the diffraction orders must be large enough in relation to the far field divergence of the incident laser radiation, since otherwise interference disturbs the arrangement of the active diffraction orders.

Such unchangeable DOEs are increasingly being replaced by programmable modulation units for dynamic shaping of the laser radiation. With programmable modulation units, the local and temporal intensity distribution of the laser radiation emitted by a laser radiation source can be adjusted. Such programmable modulation units are also referred to as “spatial light modulators (SLM)”. Spatial light modulators can also basically 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 with as short a wave as possible. In the course of the development of more powerful and long-lasting laser radiation sources for the UV range, CO2 lasers are only used relatively rarely. Excimer lasers are also rarely used these days. However, UV nanosecond lasers 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 this unless short pulse durations in the picosecond and femtosecond range are used.

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

In order to increase the processing speed during laser processing, it is known to reflect laser radiation on mirrors and to deflect it onto certain points on a workpiece surface to be processed. An arrangement of several such mirrors can be combined in one structural unit and form a mirror scanner. For example, there are known galvanometrically driven mirror scanners (galvanometer scanners) whose associated mirrors can be rotated through a defined angle by means of a rotary drive. In this way, a laser beam incident on such a mirror can be directed onto different parts of the workpiece.

Based on the foregoing, it is the object of the present invention to provide a laser processing device and a method for processing a workpiece (e.g. in the LIFT method) or for correcting imperfections in a workpiece, thus enabling fast and parallel processing of multiple processing points on the workpiece is made possible. The stated object is achieved with a device with the features of patent claim 1 and a method with the features of patent claim 24.

The device on which the invention is based is provided for machining predetermined machining locations on a workpiece. The device comprises a. a laser radiation source which is set up to generate a laser beam and to emit it along an optical path in the direction of the workpiece;

b. a beam splitting unit which is arranged downstream of the laser radiation source in the beam direction and which is set up to split the laser beam into a plurality of partial beams which are distributed in a predetermined spatial pattern;

c. a beam selection unit arranged downstream of the beam splitting unit in the beam direction, which is set up to

• forward a first number of partial beams along the optical path in the direction of the workpiece,

• deflect a second number of partial beams from the optical path, the beam selection unit also being set up to select partial beams from the spatial pattern of the partial beams in any spatial combination and assign them to the first number and the second number;

d. a beam positioning unit downstream of the beam selection unit in the beam direction, which is set up to map laser spots corresponding to the first number of partial beams on the workpiece, and is also set up to move the laser spots simultaneously and synchronously over the workpiece for positioning and / or machining, if necessary to move;

e. a control unit which is set up to process a number of processing steps, a relative position of the workpiece required to carry out the respective processing steps, on the basis of an input data set with regard to the processing points present on the workpiece or their spatial distribution Laser processing device, a processing path comprising the relative positions of the respective processing steps, as well as the number and position of partial beams required for the respective processing steps for processing the processing points, the control unit being set up for the individual processing steps

- to determine the first number and spatial arrangement of the partial beams forwarded by the beam selection unit in the direction of the workpiece,

- To determine the second number and spatial arrangement of the sub-beams derived from the beam section from the optical path, and

- To determine a positioning and processing path for a positioning and processing movement executed by the beam positioning unit of the first number of partial beams or the associated laser spots on the workpiece; wherein the beam selection unit comprises a mirror arrangement which comprises an array of MEMS mirrors or a micromirror array, with each partial beam impinging on the beam selection unit being assigned exactly one mirror of the array of MEMS mirrors or of the micromirror array, and each mirror being assigned to it is set up to assume an on position and an off position, a mirror being in the on position being set up to deflect a partial beam out of the optical path, and a mirror being in the off position being set up for this purpose is to forward a partial beam in the direction of the workpiece.

As in feature d. Coming to the expression, it can be provided to move the laser spots for positioning and for processing simultaneously and synchronously over the workpiece. However, the laser processing device can easily be used for parallel point-and-shoot processing of several processing points. A positioning or processing movement of the laser spots on the workpiece is therefore not absolutely necessary; a one-time alignment can also be sufficient (depending on the processing task). With the laser processing device according to the invention, workpieces can be processed with a defined or predetermined pattern of imperfections or of points to be processed (eg in the LIFT method). Correspondingly, the following generally refers to “processing points”, where “processing points” can mean both flaws and other processing points (eg the points to be processed in the LIFT method). In both cases, the workpiece to be processed can be built up periodically in relation to the workpiece surface, ie the surface is made up of pixels distributed in a two-dimensional manner in relation to a two-dimensional plan view. The large number of partial beams provided by the beam splitting unit of the laser processing device initially also provide a periodic arrangement of partial beams. Only with the beam selection unit can the most varied of partial beams be deflected from the optical path, so that any combinations and patterns of partial beams can be passed on along the optical path in the direction of the workpiece. In contrast to the prior art described at the beginning, with the present invention not only individual rows or columns of an array of the partial beams can be selected for projection onto the workpiece, but also any geometrical combination. It is not necessary to specify a specific spatial pattern or a number of partial beams; rather, any partial beams belonging to the periodic arrangement of the partial beams (provided via the beam splitting unit) can be selected via the beam selection unit and passed on in the direction of the workpiece.

Depending on the size of the area to be processed, a single positioning of the workpiece relative to the laser processing device may be sufficient, for example in the case in which the area comprising the processing points is smaller than the scan field accessible with the laser processing device, i.e. the area that the laser spots can achieve via positioning by means of the beam positioning unit (without relative displacement between the workpiece and the laser processing device). If, on the other hand, the area of the workpiece to be processed is larger than the scan field, 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 plurality of different machining positions (that is to say relative positions between the workpiece and the laser machining device). The required number of machining positions corresponds to the number 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 laser spots or partial beams imaged on the workpiece are determined based on the number and arrangement (i.e. the pattern) of the defects present in this processing area. After a first positioning, the partial beams directed at the workpiece can be adapted to the period on which the partial beams are based (this means the distance between the partial beams) exactly to the period of the pixels of the workpiece (this means the distance between the pixels) will. The distance between the partial beams can be set to a multiple of the pixel period, for example to ten times the period of the pixels. More precise specifications for the zoom unit will be explained in more detail at a later point. Thereafter, a positioning movement carried out via the beam positioning unit can initially result in further positioning of the partial beams or laser spots on the workpiece. The laser spots can then be processed on the workpiece. The positioning movement and processing movement carried out by the beam positioning unit takes place simultaneously and synchronously for all spots. In particular, those defects can be processed with the device according to the invention which have a similar or identical defect or material deformation. With the processing movement, it is possible to process individual sections of the workpiece across pixel boundaries.

On the basis of an input data record that reproduces 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 required for the individual processing steps for processing the processing points present there can be determined from Laser spots or partial beams formed on the workpiece can be determined. The aforementioned determination can take place, for example, under the premise of the fastest or most efficient process management or processing possible.

As mentioned at the beginning, the invention is not only directed to the laser processing device, but also to a method for processing pre-given ner processing points of a workpiece, but using the laser processing device according to the invention. In a first process step a. As mentioned, a number of processing steps, 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 is based on an input data record relating to the processing points on the workpiece or their spatial distribution as well as the number and position of partial beams required for the respective processing steps for processing the processing points.

In a further process step b. the workpiece is arranged in a workpiece recording. 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 force. Other designs of the workpiece holder are also conceivable, as well as 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 which can be moved in a horizontal plane. Accordingly, the workpiece can be moved on the xy table in a horizontal plane or working plane.

In a further process step c. a first processing step is then carried out, wherein

• the workpiece is positioned relative to the laser processing device;

• a laser beam is generated by the laser radiation source and emitted along the optical path in the direction of the workpiece;

• the laser beam is split by the beam splitting unit into a multiplicity of partial beams which are distributed in a predetermined spatial pattern;

• using the beam selection unit i. a first number of the sub-beams along the optical

Path is forwarded in the direction of the workpiece, and

ii. a second number of the partial beams are deflected from the optical path,

where partial beams are selected from the spatial pattern of the partial beams in any spatial combination and assigned to the first number and the second number, and where the first number of partial beams corresponds to the number (A) of partial beams required in the respective processing step for processing the processing points ;

• using the beam positioning unit, an arrangement of laser spots corresponding to the first number of partial beams is imaged on the workpiece and positioned in accordance with the position of the processing points to be processed in the first processing step;

• If necessary, a simultaneous and synchronous machining movement of the laser spots is carried out on the workpiece using the beam positioning unit.

In the case of processing in point-and-shoot mode, no processing movement of the laser spots has to take place on the workpiece. This is expressed through the aforementioned use of the term “if applicable.

In a further process step d. the in process step c. be described steps according to the number of specified processing steps, taking into account the in step a. specified conditions repeatedly. The design features described in connection with the laser processing device according to the invention can also be used as possible advantageous designs of the method according to the invention.

As already mentioned, the device according to the invention comprises a laser beam source which is set up to generate a laser beam and to emit it along an optical path in the direction of the workpiece. Between the Laser radiation source and the workpiece, the emitted laser beam can pass through optical functional elements, reflected, refracted, divided and deflected. Under the generated and emitted laser beam, a continuous laser beam, but in particular a laser pulse, can be present.

According to the invention, the device further 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 number of partial beams that are distributed in a predetermined spatial pattern. In addition, a beam shaping element can be provided between the laser beam source and the beam splitting unit, with which a large number of parallel partial beams with a predetermined intensity distribution can be generated from a laser beam with Gaussian intensity distribution in combination with the beam splitting unit on the workpiece, for example a top hat Intensity distribution or an annular intensity distribution.

The term "beam direction" refers in this context to the course of the laser beam. The indication of the beam splitting unit "downstream" in relation to the laser beam source means that the beam splitting unit is arranged along the optical path behind the laser radiation source. The laser beam is thus initially generated and only then enters the beam splitting unit or strikes it.

The beam splitting unit can, for example, be a diffractive optical element (DOE). For the relevant details, reference is made to the introductory part of the description. In principle, however, it is also possible to use a "spatial light modulator" known from the prior art as a beam splitting unit, as long as the latter ensures beam splitting. A spatial light modulator is to be understood as an optical component which the phase and / or the amplitude of a laser beam varies locally depending on the location. By virtue of 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 cause a phase delay in a through the Spatial light modulator generate a laser beam passing through Known modulators 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 there are diffraction patterns that depend on the exact spatial arrangement of the delaying or attenuating areas. The diffraction image generated, ie the beams of different orders on which the diffraction image is based, can also be viewed as partial beams in the context of the present invention. 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 on the workpiece can be adjusted electronically. Such variable spa tial 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 irradiated, but rather 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 an example at this point. The birefringent properties of the liquid crystal layer can be set locally in a targeted manner, for example by applying an electric field via microstructured electrodes. Corresponding spatial light modulators are sold by the Hamamatsu company under the name LCOS ("Liquid Crystal on Silicon") - Spatial Light Modulator. Transmitting variable spatial light modulators are also known; these are, for example, sold by the Jenoptik company under the name " Liquid crystal light modulators Spatial Light Modulator-S "sold. The diffraction images generated with such variable spatial light modulators can also be viewed as partial beams within the meaning of the invention, but the variant of the design of the beam splitting unit in the form of a diffractive beam splitter described above is to be preferred.

Amplitude-modulated, variable spatial light modulators based on micromechanical micromirror arrays may also be mentioned. The individually controllable micromirrors make it possible to specifically "mask out" spatial areas from the cross-section of a laser beam. A diffraction image then results by diffraction of the incident laser radiation on a "grating" in one Reflection arrangement. Diffraction images generated in this way can in principle also be viewed as partial beams within the meaning of the present invention.

As already mentioned, the laser processing device proposed by the present invention comprises a beam selection unit. With this, a first number of the partial beams can be passed on or deflected along the optical path in the direction of the workpiece. Furthermore, a second number of partial beams can be deflected from the optical path, which means that the second number of partial beams do not impinge on the workpiece. The amount of that of the first and second number (i.e. the part that is diverted in the direction of the workpiece and the part of the rays that is diverted from the optical path) depends on the number of processing points in the workpiece area, which in a certain processing step lies in the area of the scan field. If, for example, the beam splitting unit makes it possible in principle to split the laser beam into a 16 by 16 partial beam array and align it with a workpiece, and if there are only four flaws in the area of the workpiece accessible to the scan field, only four partial beams have to be made available for processing . The excess partial beams can then be deflected out of the optical path with the beam selection unit.

As already mentioned, a further component of the laser processing device according to the invention is a beam positioning unit, which is arranged downstream of the beam selection unit in the beam direction and which is set up to image laser spots corresponding to the first number of partial beams on the workpiece. Furthermore, the beam positioning unit is set up to move the laser spots simultaneously and synchronously over the workpiece for positioning and processing. The positioning can be upstream of the machining. Both steps can be repeated for the individual processing steps after positioning the workpiece relative to the Laserbear processing device. However, it is easily possible to machine a workpiece at a predetermined number of locations without performing a machining movement, e.g. B. in point-and-shoot mode.

The beam positioning unit can be a galvanometer scanner, for example. Such a scanner can have one or more mirrors, each of which is rotated about an axis of rotation by a defined angle can be. As a result, the laser beam reflected by the mirrors can be directed as a laser spot within the accessible scan field to a desired location on the workpiece.

The subclaims relate to advantageous configurations and developments of the present invention. The features mentioned in the subclaims can be used in any combination to develop the Vorrich 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 made clear by corresponding references in the claims. In particular, this also applies beyond the category boundaries of the patent claims.

According to a first embodiment of the invention, a first relay unit can be arranged between the beam splitting unit and the beam selection unit, which relay unit is set up to focus the partial beams and align them in parallel. The first relay unit can for example be designed as a single lens, e.g. as an achromat. In practice, however, the use of complex lens systems has proven advantageous.

According to a further embodiment of the present invention, a mask can be arranged between the beam splitting unit and the first relay 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.

As already mentioned above, the beam splitting unit can be a diffractive optical element (DOE). The DOE can be designed as a rotating plate, for example, which can be controlled via a control unit.

According to a further embodiment of the laser processing device, it can be provided that the beam splitting unit, i.e. the DOE, splits the laser beam into a two-dimensional array of partial beams as a spatial pattern, the two-dimensional array being an equidistant array. To name just two examples (these are not, however, limiting understand), the beam splitting unit can split an incident laser beam into an array of 18 by 18 or 16 by 16 partial beams. The distance achieved on the workpiece between the associated laser spots of the partial beams can be preset via the beam splitting unit. The partial beams divided by means of the beam splitting unit are all in a fixed angular relationship to one another. Alternatively, the beam splitting unit can also split the laser beam into a one-dimensional array of partial beams, for example 1 × 50).

According to a further advantageous embodiment, provision can be made for a beam-shaping element to be 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 a different intensity distribution, in particular into a top-hat intensity distribution or a ring-shaped intensity distribution. In particular, it can thereby be achieved that a top hat intensity distribution or an annular intensity distribution of the partial beams or laser spots projected onto the workpiece is generated in a workpiece plane.

According to a further embodiment of the laser processing device according to the invention it can be provided that a second relay unit is arranged between the beam selection unit and the beam positioning unit, which is set up to collimate the first number of partial beams so that the collimated partial beams are arranged downstream the second relay unit arranged point converge. As a result, the optical axes of the respective partial beams intersect at the point mentioned, the point providing a focal point. The second relay unit can also be designed as a single lens or as a complex lens system. The partial beams can be converged with the second relay unit, which means that they can be deflected by the second relay unit in such a way that they converge on one another. The beam directions are changed in such a way that the distance between the partial beams in the direction perpendicular to an axis belonging to the optical path is reduced to a point of the smallest distance.

According to a further advantageous embodiment of the invention it can be provided that a mask is arranged between the first relay unit and the second relay unit, which mask is set up to capture partial beams from the zeroth and / or to filter out a higher order, wherein the mask can in particular be a static mask.

According to a further embodiment of the laser processing device according to the invention it can be provided that a zoom unit is arranged between the beam selection unit and the second relay unit, which is set up to set the alignment or the distance of the first number of partial beams to one another. The alignment or the setting of the spacing of the partial beams can take place simultaneously. An alignment is in particular the adaptation of the period of the laser spots present on the workpiece to the period of the workpiece, for example a period of the pixels to be processed. In summary, it should be noted that the first relay unit aligns the partial beams parallel to one another. The second relay unit converts the beam offset of the partial beams thus generated into an angle change, this angle change is then converted back into a distance in a focusing unit, which effectively results in the change in the mentioned spot period.

According to a further embodiment of the laser processing device according to the invention it can be provided that the partial beams derived from the optical path by the beam selection unit are deflected in the direction of a beam blocking unit, for example along an optical secondary path in which the beam blocking unit is arranged as an immovable unit. The number of partial beams incident on the workpiece can be flexibly adjusted via the interaction of the beam selection unit and the beam blocking unit. This relates not only to the number of partial beams, but also to their spatial selection based on a two-dimensional partial beam array provided by the beam splitting unit. From the latter, the partial beams can be selected in any combination with regard to their position and assigned to the first or the second number of partial beams.

As already mentioned at the beginning, the invention can provide that on the basis of an input data set with regard to the processing points present on the workpiece or their spatial distribution, a number of processing steps, a relative position of the workpiece required to carry out the (respective) processing steps to the laser processing device, a processing path comprising the relative positions of the respective processing steps, as well as the number and position of partial beams required for the respective processing steps for processing the processing points. This can be done via a control unit that is either integrated into the laser processing device or is external to it. In the case of external training, a signal and data connection between the control unit and the laser processing device must be guaranteed. The determination of the above-mentioned operating parameters depends on the specific pattern of the processing points or the distribution of the processing points on the workpiece to be processed and can vary from workpiece to workpiece. For each individual case, new optimal machining parameters must be calculated.

As already indicated above, it can be provided in a further advantageous embodiment of the invention that the workpiece is arranged on an xy table that can be moved in a horizontal plane, and that the control unit is set up to move the xy table to perform a relative movement of the To control the workpiece in relation to the laser processing device. The xy table can have a suitable mechanical movement unit (this can for example include an axis system) with which the table can move.

As already mentioned, the control unit can be set up for the individual processing steps

- To determine the second number and spatial arrangement of the partial beams derived from the optical path by the beam selection unit, and

- To determine a positioning and processing path for a positioning and processing movement performed by the beam positioning unit for the first number of partial beams or the associated laser spots on the workpiece.

The conditions described above 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 a pattern (or the spatial arrangement or Distribution) of the spots depends on the number of processing points on the workpiece or their two-dimensional spatial distribution. According to the invention, the control unit can be set up to control the beam selection unit and the beam positioning unit. Only in this way can the laser processing device according to the under a. to c. are operated.

According to a further embodiment of the invention, a focusing unit can be arranged downstream of the beam positioning unit. This can be designed to focus the first number of partial beams onto the workpiece while forming the laser spots. For example, the focusing unit can be designed as a lens, preferably as an F-theta lens, which is also referred to as a plane field lens. In this context, a lens is also to be understood as a complex lens system composed of several lenses.

According to a further advantageous embodiment of the invention, a pulsed laser beam can be generated with the laser radiation source. Typical pulse repetition rates are in the range between a few Hertz and a few Megahertz. For effective 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 in material processing. The pulses can be applied with powers of more than 10 W, even more than 40 W. A power of a few 50 - 500 mW can be present per telebeam.

If pulsed laser radiation with a shorter pulse duration is used, effects that are associated with the deposition of comparable very high amounts of energy in a very short time, ie with high peak powers, gain influence. These effects can in particular be sublimation effects in which the material of the workpiece suddenly evaporates locally, ie effects in which material is removed instead of material redistribution. 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 advantageous here. In particular, pulse durations in the range of a few hundred femtoseconds up to about 10 ps allow targeted material ablation by sublimation. Typical pulse repetition rates are between 50 and 2000 Hz. Those used in the context of the present invention Pulse energies can be in the range from 5 to 1000 pJ for the laser beam before beam splitting.

Laser radiation sources with even shorter pulse durations which will be available in the future can also be used advantageously in connection with the 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 above-mentioned 100 ns can also be useful, for example if certain wavelengths are required for the machining task, or if a slower energy deposition is advantageous, for example for targeted local heating to initiate a local one Processing reaction, which can also be of a chemical nature, such as triggering a polymerization reaction, to be achieved and at the same time to avoid premature material removal.

The present invention is not limited to the use of a laser with a specific wavelength, but the use of a UV laser as a laser radiation source is advantageous, the laser radiation source preferably being a laser beam with a wavelength of 355 nm, 343 nm, 266 nm or 257 nm generated. In the ablative machining of a workpiece with a laser machining device, the wavelength can be selected to the effect that 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 this 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, broadband laser radiation sources can also be advantageous.

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

According to a further advantageous embodiment of the invention, the Strahlpo sitioning unit can be designed as a mirror scanner, in particular as a Galvanometer scanner. Accordingly, the beam positioning unit can have one or have several rotary drive (s) which are set up to move mirrors provided in the beam positioning unit for the targeted deflection and positioning of the partial beams. Galvanometer scanners for use in laser processing devices are well known.

According to the invention, the beam selection unit comprises a mirror arrangement, for example an array of MEMS mirrors or a micromirror array (DMD arrangement). The acronym MEMS stands for micro-electro-mechanical systems. The acronym DMD denotes a "digital micromirror device". Both components are known from the prior art, which is why reference is made at this point to the general technical knowledge. A significant advantage of the invention is associated with the fact that everyone can access the beam selection unit The incident partial beam is assigned to exactly one mirror of the array of MEMS mirrors or of the micromirror array. According to the configurations described, the beam selection unit can be designed to be reflective. MEMS mirrors can be operated either resonantly or quasi-statically. Such mirrors are two-dimensional elements for deflecting radiation, possible scan frequencies ranging from 0.1 kHz to 50 kHz.

The mirrors arranged in the beam selection unit can be individually controlled and tilted or moved via a control unit in order to be able to deflect each partial beam individually. As already mentioned, a first number of partial beams can be guided or deflected along the optical path in the direction of the workpiece, or removed or deflected from the optical path (the partial beams deflected from the optical path do not hit the workpiece on).

It can be provided, for example, that the individual mirrors can assume two positions, in particular an ON position and an OFF position. In the ON position, the mirrors are switched off, for example, in the OFF position, on the other hand, the mirrors are deflected by a predetermined angle, for example 10 °, in relation to the ON position. Depending on the position of the mirrors, a partial beam impinging on such a mirror is passed on (deflected) along the optical path or a corresponding beam path, or along an optical secondary path (this deviates from the optical path). By doing A beam blocking unit can for example be arranged in the optical secondary path. The partial beams impinging there are therefore not deflected in the direction of the workpiece. In summary, it should be subsumed that each mirror is set up to assume an on position and an off position, with a mirror in the on position being set up to deflect a partial beam from the optical path, and one in the Off-position mirror is set up to forward a partial beam in the direction of the workpiece. With the aforementioned mirror arrangement, in contrast to the beam selection known from the prior art, see in particular US Pat. No. 9,592,570 B2 - based on a two-dimensional spot or partial beam pattern present after the beam splitting - any partial beams or spots for forwarding in the direction of the workpiece be selected. From US Pat. No. 9,592,570 B2 it is only known to select individual spot rows or columns. It should also be emphasized that the selection carried out with the beam selection unit proposed here is preferably carried out reflective. Each individual partial beam can be individually switched dynamically and selectively.

Depending on the position of the mirrors, a preconfigured pattern of laser spots or processing spots results on the workpiece. If all mirrors are switched to their ON position, a predefined spot array results (e.g. a 10 by 10 array), with all grid positions being occupied by a laser spot. The laser spots each have an approximately constant distance. If not all mirrors are in their ON position, a certain number of the grid positions remain spot-free. With such a method, a large number of different configurations of laser spots imaged on the workpiece can consequently be provided.

According to a further advantageous embodiment, it can be provided that the mirrors are at least partially provided with a dielectric coating. Compared to a metallic surface of a mirror, an electrical coating prevents the mirror from heating up due to residual absorption of the laser radiation striking the mirror. It can be provided that each mirror is coated completely dielectrically or only partially. As already described above, in an alternative embodiment the beam selection unit can also be designed transmissive or absorptive, in particular as at least one blocking element arranged on a chip. 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, a transmission (ie a passage) of a partial beam impinging on the blocking element is made possible. In the second position, however, a partial beam striking the blocking element cannot pass through (absorption). The switching of the blocking element can be controlled via a control unit; accordingly, such a chip (or an array of such chips) is also suitable for use with the present invention.

According to a further advantageous embodiment of the invention, it can be provided that the beam selection unit is provided with a cooling unit. The cooling unit can be based on water cooling, a Peltier element, or air cooling, for example. A combination of the cooling methods mentioned above is also possible. The cooling unit prevents the mirrors arranged in the beam selection unit from heating up due to the impact of the laser radiation. The resulting waste heat and the waste heat produced by electronic components of the jet selection unit can be dissipated by means of the cooling unit.

Further advantages, refinements and developments that are related to the laser processing device according to the invention or the method according to the invention are explained in more detail using an exemplary embodiment described below. This is intended to make the invention clear to the person skilled in the art and to enable him to carry out the invention without, however, limiting the invention. The features described with reference to the exemplary embodiment can also be used to develop the laser machining device according to the invention and the method according to the invention. The embodiment is explained in more detail with reference to the figures. There shows: La shows the basic principle of the present invention, namely a schematic view of a workpiece surface provided by a plurality of pixels, with a certain number of the pixels processing points (for example imperfections in the display);

Fig. Lb the basic principle of the present invention, namely a schematic view of a two-dimensional laser spot arrangement, which is provided via a beam division;

Fig. 1c shows the basic principle of the present invention, namely the processing of the processing points with laser spots selected via a selection unit;

2 shows the schematic structure of a laser machining device according to the invention;

Fig. 3 is a schematic view of the functional principle of that of the Laserbear processing device associated beam selection unit.

Fig. 4 is a schematic view of the functional principle of that of the Laserbear processing device associated beam selection unit in a second embodiment.

With the method on which the invention is based, defects present in a workpiece 2 or on an associated surface can be machined and / or repaired. In particular, the present invention relates to the repair of displays or display components, for example OLED displays or miniLED displays. At the same time, predetermined processing points of a workpiece 2 (for example a specific pattern of processing points) can be processed with the laser processing device according to the invention, for example by way of a LIFT processing. In the following, “processing points” will be mentioned in general terms, including both imperfections and other processing points. A laser processing device is used to carry out the method, the technical features and specifications of which are described in more detail below. As already described at the outset, the laser machining device according to the invention is particularly suitable for machining machining points 1 of a workpiece 2, for example the imperfections of a display. Before going into details of the laser processing device according to the invention in detail, the basic principle will be explained quite generally with reference to FIGS. La to lc.

As FIG. 1 a shows, a workpiece 2 to be machined can comprise a grid of a plurality of pixels 30 (FIG. 1). The pixels 30 can in turn have sub-structures (not shown). Individual or several of the pixels 30 can be defined as processing points 1 (e.g. as defects, for example due to local material inhomogeneities, layer thickness deviations, etc.). The processing points 1 can also be desired processing positions that are to be subjected to LIFT processing. In the present example of FIG. 1 a, the processing points (to be processed) are identified by a diagonal line which runs through the rectangles illustrating the pixels 30. FIG. 1b shows a configuration of laser spots 18, or a two-dimensional array of three times three laser spots 18, which results from a beam splitting of a laser beam 10 with a beam splitting unit 5 (see FIG. 2). The core idea of the invention is to select only those laser spots 18 from the array of laser spots 18 with a beam selection unit 6 via a corresponding partial beam selection and to map them on the workpiece 2, which are necessary for processing the present processing points 1, i.e. three laser spots in the present example 18. As shown in FIG. 1c, the three laser spots 18 can be directed onto the processing points and subjected to a processing movement. This runs - as illustrated by the arrows - synchronously and simultaneously.

Any pattern of laser spots or machining spots can be mapped onto the workpiece 2 (in adaptation to a pattern of machining locations or defects). Without selection with the beam selection unit, a predefined spot array is obtained (for example a 3 by 3 array), all of the grid locations of the workpiece 2 shown in FIG. 1 being occupied by a laser spot. The laser spots each have an approximately constant distance. Through an adequate selection of the partial beams T transmitted in the direction of the workpiece, a certain number of the grid positions remains spot-free. Just those grid places or processing points that must also be processed are thus processed.

The method according to the invention or the laser processing device according to the invention is characterized in that such processing points 1 can be processed simultaneously in a parallelized processing process, specifically in any spatial combination. Based on the example of the repair of defects, the method described with the present invention is cheaper and faster compared to repair techniques based on single-beam laser machining.

As shown in FIG. 2, the laser processing device proposed by the present invention can project a plurality of partial beams T formed from a laser beam 10 onto the workpiece 2 to be processed, i.e. an array of partial beams T can be imaged on the workpiece 2. The number and the position of the partial beams T imaged on the workpiece 2 can be set flexibly. Furthermore, the partial beams T can be switched flexibly, i.e. only individual ones of the partial beams T belonging to the array can easily be directed onto the workpiece 2. With the laser machining device according to the invention, it is thus possible to selectively apply laser radiation (or the laser spots formed by the partial beams T) to the workpiece 2 at those pixels at which the machining points 1 are formed. In the case of a defect repair, for example, excess display material present at these processing points 1 can be ablated by laser processing. This means that processing points 1 of workpiece 2 can be processed both within a specified scan area (this means a processing area spanned by the partial beams T projected onto workpiece 2) and across this scan area. The latter is possible in particular through a relative displacement of the workpiece 2 in relation to the fixed-position laser processing device.

At this point it should be emphasized that workpieces 2 of different types can be processed with the method according to the invention or the device according to the invention, so the invention is not limited to use in the repair of display defects. In principle, the invention can be used to repair defects in a wide variety of flat products, as long as the surface can be ablated by means of the laser radiation used. In particular for workpieces 2 based on organic materials or synthetic materials, the method according to the invention can be used or the laser processing device according to the invention can be used. At the same time, the method according to the invention or the device according to the invention can also be used for machining a workpiece 2 by way of a LIFT method.

The distance D2 between the laser spots imaged on the workpiece 2 can be set flexibly. The order of magnitude of the distance D2 can be measured according to the distance between the flaws 1 on the workpiece. This will be explained below.

In the figure 2, the schematic structure of the Laserbearbei processing device according to the invention is shown. The representation there is a schematic illustration, which means that even if the representation is able to convey that e.g. the partial beams T pass through the beam selection unit 6, the beam selection unit 6 is readily - and even preferably - reflective. From the figurative representation of FIG. 2, therefore, no information about the specific functional design of the components can be derived. The individual components of the laser processing device can be designed to be both transmissive and reflective.

The laser processing device can initially comprise a workpiece holder 40 for receiving or positioning a workpiece 2. The workpiece holder 40 can be designed in the form of an xy table that can be moved in a horizontal plane. The positioning of the workpiece 2 in or on the workpiece holder 40 can be based on the force of weight or using suitable fastening or positioning means (not shown). The workpiece holder 40 can also be arranged externally to the laser processing device.

The laser processing device initially comprises a laser radiation source 3 with which a laser beam 10 is generated and emitted along an optical path 4 in the direction of the workpiece 2, in particular in the form of laser pulses. The Laser radiation source 3 is a beam splitting unit 5 nachge in the beam direction. The beam splitting unit 5 is set up to split the laser beam 10 into a plurality of partial beams T. The beam splitting unit 5 can be a diffractive optical element (DOE) which is known per se. Already with the beam splitting unit 5, the number of partial beams T can be preset. A rough adjustment of the distances between the laser spots of the partial beams T lying in a plane of the workpiece 2 can already be adjusted with the beam splitting unit 5. With the beam splitting unit 6, a laser beam 10 can be split into partial beams which provide a two-dimensional spatial pattern of laser spots 18.

In relation to the beam path, a mask 8 is provided downstream of the beam splitting unit 5, with which mask undesired partial beams T of higher order can be filtered out. The mask is an optical mask. As shown in FIG. 2, a first relay unit 7 can be provided downstream of the mask 8. The relay unit 7 is set up to focus the partial beams T impinging on the relay unit 7 (these are the partial beams T not filtered out with the mask 8) and align them in parallel. The relay unit 7 can be an individual lens (i.e. the relay unit 7 can be designed, for example, as an achromatic lens), or it can be a complex lens system.

Downstream of the relay unit 7, a beam selection unit 6 is provided which is set up to forward or deflect a first number A1 of the partial beams T along the optical path 4 in the direction of the workpiece 2 to be processed. Furthermore, the beam selection unit 6 is set up to deflect a second number A2 of the partial beams T out of the optical path 4. The deflection can take place in the direction of an optical secondary path (not shown), for example in the direction of a beam blocking unit 13 (FIG. 3).

According to a first embodiment, the beam selection unit 6 can comprise a mirror arrangement 15 which is composed of an array of individual mirrors 16. The mirrors 16 can be MEMS mirrors or micromirrors. According to the invention, it is provided that each partial beam T impinging on the Strahlse lection unit 6 strikes a maximum or exactly one mirror 16. The mirrors 16 can be controlled individually via a control unit and are tilted or moved in order to be able to deflect each partial beam T individually. As already mentioned, a certain number A1 of the partial beams T can be passed on or deflected along the optical path 4 in the direction of the workpiece 2, or else can be removed from the optical path 4.

As schematically illustrated in FIG. 3, the mirrors 16 can, for example, assume two positions, in particular an ON position 100 and an OFF position 200. In the ON position 100, the mirrors 16 are switched off, for example, in the OFF position 200 however, the mirrors 16 are deflected by a predetermined angle, for example 10 °, with respect to the ON position 100. Depending on the position of the mirror 16, a partial beam T impinging on such a mirror 16 is guided (deflected) along the optical path 4 or a corresponding beam path or along an optical secondary path (this deviates from the optical path 4). A static beam blocking unit 13 can, for example, be arranged in the secondary optical path. The partial beams T impinging there are therefore not deflected in the direction of the workpiece 2 (in FIG. 3 the beams derived in the direction of the beam blocking unit 13 are shown in dashed lines). The ON position 100 therefore leads to a deflection of the partial beams T in the direction of the beam blocking unit 13, while the OFF position 200 leads to the relaying of the partial beams T along the optical path 4 in the direction of the workpiece 2.

Depending on the position of the mirror 16, a preconfigured pattern of laser spots or machining spots results on the workpiece 2. If all mirrors 16 are switched to their ON position 100, a predefined spot array results (e.g. a 10 by 10 array), with all grid positions being occupied by a laser spot. The laser spots each have an approximately constant distance. If all of the mirrors 16 are not in their ON position 100, a certain number of the grid positions remain spot-free. With such a method, a large number of different configurations of laser spots imaged on the workpiece 2 can consequently be provided.

As already described above, in an alternative embodiment the beam selection unit 6 can also be transmissive or absorptive (FIGS. 4a, 4b), in particular as at least one blocking element 13 arranged on a chip 19. However, such chips are freely available on the market (please refer e.g. https://www.preciseley.com/mems-optical-shutter.html). The mentioned blocking element 13 is movable within a chip plane at least from a first to a second position. In the first position (FIG. 4a), transmission (that is, passage through) of a partial beam T impinging on the blocking element 13 is enabled. In the second position (cf. FIG. 4b), on the other hand, a partial beam T impinging on the blocking element 13 is prevented from passing through (absorption). The switching of the blocking element 13 can be controlled via a control unit; accordingly, such a chip 19 (or an array of such chips) is also suitable for use with the present invention.

A further mask 17 can be provided between the first relay unit 7 and the second relay unit 11. The mask 17 can in particular be arranged in front of the beam selection unit 6 and provided for filtering out higher orders and the zero order, cf. the illustration according to FIG. 2.

As can also be seen from FIG. 2, a zoom unit 12 can be provided downstream of the beam selection unit 6. The zoom unit can be set up to simultaneously adapt the partial beams T in their alignment or inclination and their spacing relative to one another. Correspondingly, the adjustment of the partial beams T carried out via the zoom unit 12 also has an indirect effect on the alignment and the spacing of the laser spots projected onto the workpiece 2. As shown in FIG. 2, a distance D1 present between the partial beams and a distance D2 between the laser spots present on the workpiece 2 can be adjusted via the zoom unit 12.

A second relay unit 11 is arranged downstream of the zoom unit 12. The second relay unit 11 is set up to collimate the first number A1 of partial beams T so that the collimated partial beams T converge in a point 50 (a focal point) arranged downstream of the second relay unit 11. In fact, a bundle of partial beams is brought together in the focal point. The second relay unit 11 can - like the first relay unit 7 - also be an individual lens or a complex lens system. Furthermore, the laser processing device comprises a beam positioning unit 9, which can be a galvanometer scanner, for example, which is set up to image laser spots corresponding to the first number A1 of partial beams T on the workpiece 2. Depending on the pattern set via the beam selection unit 6, a defined spot pattern - or an arrangement of partial beams T - is projected onto the workpiece 2. According to the present spot pattern, both a simultaneous and synchronous positioning movement of the laser spots projected onto the workpiece 2 and a simultaneous and synchronous machining movement can be carried out by means of the beam positioning unit 9. The positioning movement can be carried out within a scan area accessible via the beam positioning unit 9. Sub-structures of individual pixels can also be processed using the processing movement described.

With regard to the machining method also proposed by the invention, it should be noted that a specific machining point of the workpiece 2 can be controlled via a relative displacement between workpiece 2 and laser machining device, i.e. the scan field is positioned in a specific sub-area of the workpiece surface. According to the distribution of the processing points 1 or the processing point pattern present in this partial area of the workpiece 2, processing is carried out which is adapted to this processing point distribution. This means that the number of partial beams T impinging on workpiece 2 or of the associated laser spots is adapted to the number of processing points 1 present in the section to be processed. The spatial arrangement of the laser spots 18 is also adapted to the spatial distribution of processing points in the respective section of the workpiece 2. The number and spatial arrangement of the partial beams T or the associated laser spots 18 can be set via a control unit which can be in a signal and data connection with the beam selection unit 6, the zoom unit 12 and the beam positioning unit 9. Furthermore, the control unit can also have a signal and data connection with the beam splitting unit 5.

A component of the beam positioning unit 9 can also be a focusing unit 14 that directs those partial beams T deflected by the galvanometer scanner onto the Workpiece 2 focused. The laser spots 18 of the partial beams T (corresponding to the set spot pattern) are imaged on the workpiece 2.

List of reference symbols

1 processing point

2 workpiece

3 laser radiation source

4 optical path

5 beam splitting unit

6 beam selection unit

7 first relay unit

8 mask

9 Beam positioning unit

10 laser beam

11 second relay unit

12 zoom unit

13 beam blocking unit

14 Focusing unit, F-theta lens

15 Mirror arrangement

16 mirrors

17 mask

18 laser spot

19 chip

30 pixels

40 workpiece holder

100 ON position

200 OFF position

T partial beam

Al first number

A2 second number

Dl distance

D2 distance

Claims

1. Laser processing device, in particular 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 (10) and to emit it along an optical path (4) in the direction of the workpiece (2);

b. a beam splitting unit (5) arranged downstream of the laser radiation source (3) in the beam direction, which is set up to split the laser beam (10) into a plurality of partial beams (T) which are distributed in a predetermined spatial pattern;

c. a beam selection unit (6) arranged downstream of the beam splitting unit (5) in the beam direction, which is set up to

• to forward a first number (Al) of the partial beams (T) along the optical path (4) in the direction of the workpiece (2),

• deflect a second number (A2) of the partial beams (T) from the optical path (4), the beam selection unit (6) also being set up to add partial beams (T) from the spatial pattern of the partial beams (T) in any spatial combination select and assign to the first number (A1) and the second number (A2);

d. a beam positioning unit (9) which is arranged downstream of the beam selection unit (6) and is configured to image laser spots (18) corresponding to the first number (A1) of partial beams (T) on the workpiece (2) and is also configured to do so to move the laser spots (18) simultaneously and synchronously over the workpiece (2) for positioning and / or processing, if necessary;

e. a control unit which is set up to, on the basis of an input data record with regard to the processing points (1) present on the workpiece (2) or their spatial distribution, a number of processing steps, one for executing the respective Processing steps required relative position of the workpiece (2) to the laser processing device, a processing path comprising the relative positions of the respective processing steps, as well as the number (A) and position of partial beams (T) required for the respective processing steps for processing the processing points (1), whereby the control unit is set up for each of the individual processing steps

- to determine the first number (Al) and spatial arrangement of the partial beams (T) forwarded by the beam selection unit (6) in the direction of the workpiece (2),

- to determine the second number (A2) and spatial arrangement of the partial beams (T) derived from the optical path (4) by the beam selection unit (6), and

- To determine a positioning and processing path for a positioning and processing movement carried out by the beam positioning unit (9) of the first number (Al) of the partial beams (T) or the associated laser spots on the workpiece (2); wherein the beam selection unit (6) comprises a mirror arrangement (15) which comprises an array of MEMS mirrors or a micromirror array, with exactly one mirror (16) of the array of MEMS for each part beam (T) impinging on the beam selection unit (6) Mirrors or the micromirror array is assigned, and each mirror (16) is set up to take an on position (100) and an off position (200), with a mirror in the on position (100) (16) is set up to deflect a partial beam (T) out of the optical path (4), and a mirror (16) in the off position (200) is directed to direct a partial beam (T) in the direction of the Forward workpiece (2).

2. Laser processing device according to claim 1, characterized by a first relay unit (7) arranged between the beam splitting unit (5) and the beam selection unit (6) which is set up to focus the partial beams (T) and align them in parallel.

3. Laser processing device according to one of claims 1 or 2, characterized by a marked between the beam splitting unit (5) and the first relay unit (7) arranged mask (8) which is set up to filter out partial beams (T) of higher order .

4. Laser processing device according to one of the preceding claims, characterized in that the beam splitting unit (5) is a diffractive optical element.

5. Laser processing device according to one of the preceding claims, characterized in that a beam shaping element is arranged between the laser radiation source (3) and the beam splitting unit (5), which is set up to convert a Gaussian intensity distribution of the laser beam (10) into a different intensity distribution , especially in a top-hat intensity distribution or a ring-shaped intensity distribution.

6. Laser processing device according to claim 4, characterized in that the beam splitting unit (5) is set up to split the laser beam (10) into a two-dimensional array of partial beams (T) as a spatial pattern, the two-dimensional array being an equi-distant one Array is.

7. Laser processing device according to one of the preceding claims, characterized in that between the beam selection unit (6) and the beam positioning unit (9) a second relay unit (11) is angeord net, which is set up to the first number (Al) of the partial beams (T) to collimate so that the collimated partial beams (T) converge in a point (50) arranged downstream of the second relay unit.

8. Laser processing device according to one of the preceding claims, characterized by a mask (17) which is arranged between the first relay unit (7) and the second relay unit (11) and is set up for partial beams (T) from zero and / or to filter out a higher order, the mask (17) being in particular a static mask.

9. Laser processing device according to one of the preceding and workman che, characterized by a between the beam selection unit (6) and the second relay unit (11) arranged zoom unit (12), which is set up to the alignment or the distance (Dl) the first number (Al) of the partial beams (T).

10. Laser processing device according to claim 9, characterized in that via the zoom unit (12) indirectly the alignment or the stand (D2) of the partial beams (T) or the partial beams (T) imaged on the workpiece (2) associated laser spots (18) can be adjusted to one another.

11. Laser processing device according to one of the preceding workman, characterized in that the partial beams (T) derived from the beam selection unit (6) from the optical path (4) are deflected in the direction of a beam blocking unit (13).

12. Laser processing device according to one of the preceding claims, characterized in that the partial beams (T) derived from the optical path (4) by the beam selection unit (6) are derived along a secondary optical path.

13. Laser processing device according to one of the preceding and workman surface, characterized in that the workpiece (2) is arranged on an xy table movable in a horizontal plane, and that the control unit is set up to perform a relative movement of the xy table Controlling the workpiece (2) in relation to the laser processing device.

14. Laser processing device according to one of the preceding claims, characterized in that the control unit is set up to control the beam selection unit (6) and the beam positioning unit (9).

15. Laser processing device according to one of the preceding claims, characterized by a downstream of the beam positioning unit (9) arranged focusing unit (14), which is set up to focus the first number (A1) of partial beams (T) on the workpiece (2) with the formation of the laser spots (18).

16. Laser processing device according to claim 15, characterized in that the focusing unit (14) is an F-theta lens.

17. Laser processing device according to one of the preceding claims, characterized in that the laser radiation source (3) is set up to generate a pulsed laser beam (10).

18. Laser processing device according to one of the preceding claims, characterized in that the laser radiation source (3) is a UV laser, the UV laser in particular a laser beam (10) with a wavelength of 355 nm, 343 nm, 266 nm or 257 nm generated.

19. Laser processing device according to one of the preceding claims, characterized in that the beam positioning unit (9) is designed as a mirror scanner, in particular as a galvanometer scanner.

20. Laser processing device according to one of the preceding claims, characterized in that the mirrors (16) are at least partially provided with a dielectric coating.

21. Laser processing device according to one of the preceding claims, characterized in that the beam selection unit (6) is reflective.

22. Laser processing device according to one of the preceding claims, characterized in that the beam selection unit (6) is designed to be transmissive or absorptive.

23. Laser processing device according to claim 22, characterized in that the beam selection unit (6) is designed as at least one blocking element arranged on a chip, the at least one blocking element being movable within a chip plane at least from a first to a second position, in which first position a transmission a partial beam (T) impinging on the blocking element is enabled, and in the second position a passage of a partial beam (T) impinging on the blocking element is prevented.

24. A method for processing predetermined processing points (1) of a workpiece (2) using a device according to claim 1, comprising at least the following steps: a. On the basis of an input data record with regard to the processing points (1) present on the workpiece (2) or their spatial distribution, a number of processing steps, a relative position of the workpiece (2) to the laser processing device required for executing the respective processing steps, is Rela tive positions of the respective processing steps comprehensive processing path as well as the number (A) and position of partial beams (T) required for the respective processing steps for processing the processing points (1) specified;

b. the workpiece (2) is arranged in a workpiece holder; c. a first processing step is carried out, wherein

• the workpiece (2) is positioned relative to the laser machining device;

• a laser beam (10) from the laser radiation source (3)

generates and is emitted along the optical path (4) in the direction of the workpiece (2);

• the laser beam (10) from the beam splitting unit (5) is divided into a plurality of partial beams (T), which are distributed in a given spatial pattern before;

• using the beam selection unit (6)

i. a first number (A1) of the partial beams (T) is passed along the optical path (4) in the direction of the workpiece (2), and

ii. a second number (A2) of the partial beams (T) is deflected from the optical path (4),

where partial beams (T) are selected from the spatial pattern of the partial beams (T) in any spatial combination and the first number (Al) and the second number (A2) are assigned, and the first number (Al) of the partial beams to the number (A) of the parts required in the respective processing step for processing the processing points (1) beam (T. ) corresponds;

• using the beam positioning unit (9), an arrangement of laser spots corresponding to the first number (A1) of partial beams (T) is mapped onto the workpiece (2) and is positioned according to the position of the processing points to be processed in the first processing step;

• if necessary using the beam positioning unit (9), a simultaneous and synchronous machining movement of the laser spots on the workpiece (2) is carried out;

d. in the process step c. The steps described are based on the number of specified processing steps, taking into account the steps in step a. specified conditions.

25. The method according to claim 24, characterized in that the method is carried out using a device according to one of claims 2 to 23.

26. The method according to claim 24 or 25, characterized in that the workpiece (2) is subjected to a positioning relative to the laser processing device for the execution of a respective processing step via a movement mediated by the xy table.

27. The method according to any one of claims 24 to 26, characterized in that the laser spots are subjected to positioning via the zoom unit (12) and / or the beam positioning unit (9).