WO2023194320A1

WO2023194320A1 - Device for generating a defined laser line on a working plane

Info

Publication number: WO2023194320A1
Application number: PCT/EP2023/058708
Authority: WO
Inventors: Andreas Heimes; Julian Hellstern; Christoph Tillkorn
Original assignee: Trumpf Laser- Und Systemtechnik Gmbh
Priority date: 2022-04-06
Filing date: 2023-04-03
Publication date: 2023-10-12
Also published as: DE102022108300A1

Abstract

The invention relates to a device (10) for generating a defined laser line on a working plane (24), having multiple laser light sources (12a, 12b), each of which is designed to generate a laser beam bundle (16a, 16b, 16c) with a defined divergence. The laser beam bundles (16a, 16b, 16c ) define a beam direction (z) which intersects the working plane (30) and are designed to overlap in front of the working plane (30) at a first distance (A) thereto, and the laser beam bundles (16a, 16b, 16c) have a beam profile in the region of the working plane (30), said beam profile having a long axis (LA) with a long axis beam width and a short axis (SA) with a short axis beam width perpendicularly to the beam direction (z). The device (10) additionally has a first optical assembly (14) which is designed to generate a defined beam profile in the short axis (SA) on the working plane (30). The device (10) is characterized in that it additionally comprises a second optical assembly (18) which has multiple separate second sub-units (18a, 18b, 18c) which are designed to generate a beam profile with a homogenous angle in the long axis (LA) on the working plane (30).

Description

Device for generating a defined laser line on a working plane

The present invention relates to laser systems for optically generating line-shaped illumination in a working plane.

[0002] Such a device is basically known from WO 2018/019374.

The line-shaped laser illumination of such a device can advantageously be used to thermally process a workpiece. The workpiece can, for example, be a plastic material on a glass plate that serves as a carrier material. The plastic material can in particular be a film on which organic light-emitting diodes, so-called OLEDs, and/or thin-film transistors are produced. OLED films are increasingly being used for displays in smartphones, tablet PCs, televisions and other devices with screen displays. After producing the electronic structures, the film must be removed from the glass carrier. This can be done with laser illumination in the form of a thin laser line, which is moved at a defined speed relative to the glass plate and thereby breaks the adhesive bond of the film through the glass plate. In practice, such an application is often referred to as LLO or Laser Lift Off.

Another widely used application for the sequential illumination of a workpiece with a defined laser line can be the line-by-line melting of amorphous silicon on a carrier plate. Here too, the laser line is moved at a defined speed relative to the workpiece surface. By melting and then cooling, the comparatively inexpensive amorphous silicon can be converted into higher-quality polycrystalline silicon. In practice, such an application is often referred to as Solid State Laser Annealing (SLA), Sequential Lateral Solidification (SLS) or Excimer Laser Annealing (ELA).

For such applications, a laser line is required on the working plane which is as long as possible in one direction in order to cover the widest possible working surface and which, in comparison, is very short in the other direction in order to be suitable for the respective process to provide the required energy density. Accordingly, it is desirable a long, thin laser line with a very large aspect ratio of line length to line width. For typical applications, a line length of 1000mm or even more, sometimes even over 2000mm, with a line width of the order of 20pm may be desirable. The direction in which the laser line runs is usually referred to as the long axis (LA) and the line width as the short axis (SA) of the so-called beam profile. As a rule, the laser line should have a defined intensity curve in both axes.

[0006] Line focus systems, as disclosed in WO 2018/019374 A1, generally include one or more large optics for generating long but thin laser lines. The extent of the large optics is typically greater than the length of the line in the working plane. The problem is that the large optics represent a significant cost item. The complexity associated with the production of such large-scale optics is increasing, particularly when producing very large line lengths. In addition, when generating laser lines of 1500mm or more when using large optics, there is often a space problem in terms of the size of typical test or working chambers.

[0007] Furthermore, it should be borne in mind that various other criteria also play a role for the various applications of line focus systems. In fact, an optical arrangement, such as that disclosed in WO 2018/019374 A1, in no way meets the requirements for a precise SLA application.

Against this background, it is an object of the present invention to provide an improved line focus system with which large line lengths can be produced without loss of quality but at lower costs, particularly for SLA applications.

According to one aspect of the present invention, to solve this problem, a device for generating a defined laser line on a working plane is proposed, with several laser light sources, each of which is set up to generate a laser beam bundle of predefined divergence, the laser beam bundles define a beam direction that intersects the working plane, and are designed to overlap at a first distance in front of the working plane, and wherein the laser beam bundle in the area of the working plane has a beam profile which has a long axis perpendicular to the beam direction with a long axis beam width and a short axis with a short-axis beam width, and a first optical arrangement which is set up to generate a predefined beam profile in the short axis in the working plane, characterized in that the device further comprises a second optical arrangement which has a plurality of separate second ones Has subunits that are designed to generate an angularly homogeneous beam profile in the long axis in the working plane.

[0010] The term “laser light source” does not necessarily mean a source in which the laser light is generated. This can be any arrangement from which laser light emanates in the form of a laser beam with a defined divergence.

The distance A is defined as the distance starting from the laser light sources.

Preferably, the second subunits are each designed to generate an angle-homogeneous beam profile in the long axis in the working plane.

The term “angularly homogeneous” is to be understood as meaning that the spectrum of the angles of incidence of the laser beams arriving on the working plane is homogeneous, i.e. that the angular distribution and/or the angular spectrum of the incident beams at every point of a laser line (to be stitched) along the long axis (or at least in a central area along the long axis) on or in the working plane is the same. The angle of incidence of the laser beams on the working plane is defined as an angle relative to a surface normal of the working plane. Preferably, the angle of incidence, typically referred to as angle 0, is 0 = 0°. In order to obtain such angles of incidence on the working plane, the second optical arrangement must have a telecentric (image-side) create a real image. The beam cones of the laser beams all hit the image plane or working plane perpendicularly. Depending on the application, other (homogeneous) angles of incidence are also conceivable.

Due to the homogeneous angular spectrum generated, the device mentioned is particularly suitable for SLA applications. For example, while the angle of incidence of the individual laser beams does not play an important role when annealing architectural glass using an infrared (lR) line, the SLA process is extremely sensitive to the angular spectrum of the incident light.

By using several laser light sources, which (each) generate long but thin laser lines, a laser line of great length is created when the sources are arranged accordingly in the working plane. The process of combining short laser lines into one long laser line is called “stitching”. In the present device, a high cost saving results from the use of several (correspondingly small) second subunits to generate the beam profile in the long axis. This means that the use of costly large optics that are supposed to work in the long axis can be dispensed with.

[0016] In view of this, the above-mentioned task is completely solved.

In particular, it can be provided that the laser beam bundles generated by different laser light sources do not pass through a common optical element which contributes to the overlap of the laser beam bundles and/or which influences the laser beam bundles in the long axis and/or which has an effect on the laser beam bundles in the has a long axis. In particular, the device according to the invention does not have such an optical element. This means that in particular several small optics can be used, which are assigned to the respective laser beam bundles. These are easier to handle and integrate than large-sized optics.

In a preferred embodiment of the invention, the second optical arrangement is arranged in the beam path of the plurality of laser beam bundles in the beam direction in front of the first distance. In other words, the second subunits are arranged at a location in the beam path where the individual beam bundles of the multiple laser light sources do not yet overlap. In this way, the beam profile of each individual beam bundle can be processed or influenced separately in the long axis. The arrangement mentioned creates several optical channels (beam channels) that can be addressed separately. In the event that due to a material defect or similar. If the line profile in the long axis in the working plane does not turn out as desired, it is sufficient to replace the corresponding faulty second subunit instead of having to replace an entire large optics system.

In a further embodiment, the laser light sources are arranged at an equidistant distance from one another and/or the second subunits are arranged at an equidistant distance from one another.

The distance can be a distance in the lateral direction, i.e. a direction transverse to the beam direction, or a distance in the direction of the beam path. Mixed forms are also conceivable. The laser light sources are preferably arranged at an equidistant distance in a line parallel to the x-direction or the working plane. Further preferably, at least some of the second subunits are arranged at an equidistant distance in a line parallel to the x-direction or the working plane. It is particularly conceivable that the second subunits are arranged in groups at equidistant intervals in a line parallel to the working plane.

With an arrangement in which both the laser light sources and the second optical subunits are arranged at an equidistant distance in a line parallel to the x-axis or the working plane, the laser lines from the individual beam bundles can easily form a long laser line be “stitched” together. Depending on the divergence of the beam bundles and the distance between the laser light sources, a homogeneous intensity curve of the stitched line in the working plane can be achieved.

In a further embodiment, the second subunits can be displaced and/or tilted in a direction parallel and/or perpendicular to the working plane.

This embodiment is advantageous in order to achieve the desired line profile on the working plane by adjusting corresponding subunits. In particular, this can It must be ensured that the beam profile of the laser line in the working plane is homogeneous in terms of angle and intensity.

In a preferred embodiment of the invention, the second subunits comprise a homogenizer which is designed to distribute laser beams of the laser beam bundle homogeneously, in particular angularly homogeneously, in the long axis. Preferably, the second subunits each comprise a homogenizer.

[0026] More specifically, the homogenizer is designed to generate both a homogeneous intensity spectrum and a homogeneous angular spectrum in the long axis. The homogenizer preferably acts in such a way that different beam segments of the laser beam striking it are mixed and/or superimposed on one another. For this purpose, the homogenizer can, for example, comprise at least one lens array, wherein the at least one lens array can have a plurality of cylindrical lenses extending along respective cylinder axes. Preferably, the cylindrical lenses are geometrically dimensioned such that the laser beam passes through a large number of cylindrical lenses lying next to one another. In principle, the homogenizer can be an imaging or a diffractive homogenizer.

In a further embodiment, the second subunits comprise a transformer which is designed to expand one of the laser beam bundles along the long axis.

With this embodiment, the aspect ratio of the laser beam bundle can be optimized (even further and/or more efficiently) with regard to the desired laser line in the working plane. The transformer can, for example, comprise a transparent, monolithic, plate-shaped element, the element having a front side and a back side parallel to the front side. The front and back preferably have a reflective coating, so that an incident laser beam experiences multiple reflections within the plate-shaped element before it emerges expanded on the back. In other exemplary embodiments, the transformer can be implemented as or with the aid of a diaphragm. Basically, the transformer leaves the angular distribution of a laser beam untouched. Accordingly, in devices that only have a transformer in a laser beam as a second optical arrangement (and in which no further optical arrangement influences the angular distribution in the long axis) a homogeneous angular spectrum in the working plane is only possible if the laser beam bundle entering the transformer is already angularly homogeneous.

In another embodiment, the second subunits comprise a beam splitter which is designed to divide one of the laser beam bundles into a plurality of partial beams.

In principle, the beam splitter leaves the angular distribution of a laser beam untouched. Accordingly, in devices which only have a beam splitter in a laser beam bundle as a second optical arrangement (and in which no further optical arrangement influences the angular distribution in the long axis), a homogeneous angular spectrum in the working plane is only possible if this is in the Beam splitter incoming laser beam bundle is already angularly homogeneous.

In a further embodiment, the first optical arrangement has a plurality of first subunits that are separate from one another. The first subunits can include, for example, a transformer or a beam splitter. Other optical devices, such as a focusing unit acting in the short axis, are also conceivable. Preferably, the first subunits can be displaced parallel and/or perpendicular to the working plane.

Preferably, the first subunits are each set up to generate a predefined beam profile in the short axis in the working plane. In particular, it is desirable that the first subunits generate a rectangular intensity profile (so-called top hat profile) or a Gaussian profile in the short axis. By separating both the beam bundles and the first optical arrangement into several subunits, the short-axis profile for each individual beam bundle can be influenced independently of the other beam bundles. This enables targeted creation of laser lines on the working plane.

In a further embodiment, only one or more further optical arrangements are arranged between the second optical arrangement and the working plane, which have no influence on the angular spectrum of the laser beam bundles in the long axis. This ensures that the homogeneous angular spectrum generated by the second optical arrangement is not destroyed in front of the working plane or before it hits the workpiece to be machined or that no inhomogeneities are introduced.

In principle, the order of the first, second and each further optical arrangement in the beam direction is arbitrary. For example, the first optical arrangement can be arranged in front of the second optical arrangement or behind the second optical arrangement, as long as it does not influence the angular spectrum of the laser beam bundle in the long axis. The only decisive factor is that the image generated by the second optical arrangement in the long axis towards the working plane is not destroyed by the first and/or a further optical arrangement. What is particularly crucial is that there is no arrangement downstream of the second optical arrangement that imprints a phase on the respective laser beams with respect to the long axis or that has a phase-changing effect in the long axis. In this respect, the presence of any protective glass downstream of the second optical arrangement and in front of the working plane or a workpiece located there is not a problem. In a further preferred embodiment, the laser light sources are UV sources, in particular UV sources whose laser beam bundles have a beam profile of the same intensity.

UV laser beams are particularly required in SLA applications. The same intensities of the laser beam bundles enable simpler optical arrangements, in particular a simpler third optical arrangement, since with this configuration a homogeneous intensity spectrum in the long axis is easier to achieve.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or alone, without departing from the scope of the present invention.

Embodiments of the invention are shown in the drawings and are explained in more detail in the following description. Show it:

1A shows a first exemplary embodiment of the new device, 1B shows the intensity profile of the laser line generated by the device shown in FIG. 1A in a first plane,

1C shows the intensity curve of the laser line generated by the device shown in FIG. 1A in a second plane,

1D shows the intensity curve of the laser line generated by the device shown in FIG. 1A in a third plane,

1E shows the intensity curve of the laser line generated by the device shown in FIG. 1A in a fourth plane,

2A shows a representation of an optical arrangement from the prior art,

2B shows a representation of another optical arrangement from the prior art

Technology,

3 shows a simplified, schematic representation of several identical sources and the laser beam bundles generated by the sources,

4 shows a representation of a second exemplary embodiment of the new device,

5A shows a first exemplary embodiment of an arrangement of beam splitters and a mirror,

5B shows a second exemplary embodiment of an arrangement of beam splitters and a mirror,

6A shows an exemplary embodiment of a transformer,

6B shows an exemplary embodiment of an arrangement of transformers,

7A shows a first exemplary embodiment of a homogenizer, and Fig. 7B shows a second embodiment of a homogenizer.

In Fig. 1A, a first exemplary embodiment of the new device is designated in its entirety by reference number 10. The device 10 has several laser light sources (not shown) which generate laser light in the ultraviolet range and radiate it in the z direction. The laser light sources are arranged at equal distances from one another on a line that runs parallel to the working plane 24 and the x-axis. The laser light sources emit laser beam bundles 16a, 16b and 16c of the same divergence and intensity in the direction of the working plane 30. The laser beam bundles 16a, 16b and 16c strike a second optical arrangement 18 in front of a first distance A (not shown). This comprises a total of six second subunits 18a, 18b, 18c, 18d, 18e and 18f, the three second optical subunits 18a, 18b and 18c include three transformers 24a, 24b and 24c and wherein the three second optical subunits 18d, 18e and 18f include three homogenizers 22a, 22b and 22c. The transformers are designed to expand the laser beam bundle directed at them with a predefined divergence in the x direction. This means that the transformers each generate a laser beam of predefined divergence. More precisely, the transformers generate a trapezoidal intensity profile of the laser beam bundles in the x direction. The three homogenizers 22a, 22b and 22c are each arranged in one of the three laser beam bundles 16a, 16b and 16c. In addition, the device includes a first optical arrangement, which is not shown in FIG. 1A, as are the laser light sources.

The device 10 generates a laser line (not shown here) in the area of the working plane 30 in order to process a workpiece (not shown here) that is placed in the area of the working plane 30. The laser line runs in a direction parallel to the x-axis. The laser line has a line width, which is viewed here in the direction of a y-axis running orthogonally to the x-axis (and z-axis). Accordingly, the x-axis corresponds to the long axis and the y-axis corresponds to the short axis of the beam profile formed on the working plane 30. In other words, the beam profile has a long axis LA with a long-axis beam width in the x-direction and a short axis SA with a short-axis beam width in the y-direction. The respective beam width can be, for example, the width of the intensity profile I (x, y) at 50% of the maximum intensity (FWHM, Full Width at Half Maximum) or, for example, the width between the 90% intensity values (Full Width at 90% Maximum, FW@90%) or defined in another way.

In some (preferred) embodiments, the workpiece may include a surface layer of amorphous silicon, which is converted to polycrystalline silicon using the laser line. For processing, the laser line can be moved in a direction of movement relative to the workpiece in the working plane of the working plane 30.

Due to the divergence of the laser beam bundles 16a, 16b and 16c, after a certain path length, the first distance A, the laser beam bundles 16a, 16b and 16c are superimposed downstream of the beam (i.e. in the z direction). In fact, from the first level 32 onwards, beam bundles 16a, 16b and 16c are superimposed. Downward from the beam towards the fourth level 36, the overlapping of the individual bundles increases more and more.

The position of the working plane 30 is chosen so that the laser beam bundles 16a, 16b and 16c are superimposed here in such a way that a homogeneous intensity profile of the laser line is created. In addition to the telecentric imaging of the laser beams on the working plane 30 by the homogenizers 22a, 22b and 22c, it is important that the intensity profile of the laser light on the working plane 30 is homogeneous. Due to the homogenizers 22a, 22b and 22c, the laser beam bundles 16a, 16b and 16c have a homogeneous intensity spectrum when viewed individually, but the superimposition of the beam bundles in the area of the fourth level creates 36 intensity peaks which destroy the homogeneous intensity curve. This can also be seen from FIG. 1 E, which shows the intensity spectrum of the laser line in the fourth plane 36 in the x direction. On the other hand, the intensity curve in the first and second levels 32 and 34 is also not completely homogeneous, since some areas in these levels are less illuminated than others. This can be seen in Figures 1B and 1C, which show the intensity curve in levels 32 and 34, respectively. Only in the third level or the working plane 30 is there not only a homogeneous angle spectrum but also a homogeneous intensity spectrum of the laser line (see FIG. 1 D).

1 B shows the intensity curve of the laser line generated by the device shown in FIG. 1 A in the first plane 32. The intensity curve l(x) is in particular along the long axis, i.e. in the x direction. The intensity profile of the individual laser beams 16a, 16b and 16c is trapezoidal along this axis. Because the intensity profile of the individual laser beam bundles 16a, 16b and 16c is trapezoidal and the overlap of the individual laser beam bundles 16a, 16b and 16c in the first plane 32 is still quite small, dips in intensity occur at the overlapping points.

1C shows the intensity curve of the laser line generated by the device shown in FIG. 1A in the second plane 34. The intensity curve l(x) is shown in particular along the long axis, i.e. in the x direction. Because the overlap of the individual laser beam bundles 16a, 16b and 16c in the second level 34 is slightly larger than in the first level 32, the intensity drops are somewhat smaller than in FIG. 1 B.

1D shows the intensity curve l(x) of the laser line generated by the device shown in FIG. 1A in the third plane or the working plane 30. Here the overlap of the laser beam bundles 16a, 16b and 16c is such that The resulting intensity profile l(x) is largely homogeneous (i.e. constant). This means that the intensity of the laser line at the locations of overlapping laser beam bundles is (essentially) the same as at the locations where there is no overlap.

1 E shows the intensity curve l(x) of the laser line generated by the device shown in FIG. 1 A in the fourth plane 36. In this plane, the overlap of the trapezoidal intensity curves of the individual laser beam bundles is already so large that intensity peaks arise in the intensity profile l(x) of the combined laser line.

2A shows an optical arrangement from the prior art. The optical arrangement includes a (non-imaging) homogenizer 22, comprising a microlens array and a focusing unit 28. A beam 16 hits the microlens array. The microlens array is set up to mix or superimpose individual beam segments of the laser beam bundle 16, so that the intensity curve is homogenized with respect to the direction in which the beam bundle cross section extends elongated (here x direction). The microlens array, which produces a telecentric image or a homogeneous angular spectrum, is followed downstream of the beam (ie in the z direction) by a plano-convex lens as a focusing unit 28. The distance a between the homogenizer 22 and the focusing unit 28 is dimensioned such that the Lens images the homogeneous angular spectrum on the working plane 30 or produces an image that is telecentric. In particular, the distance a just corresponds to the focal length of the lens (so-called “2f setup”). In other words, the distance a is selected such that the angular spectrum of the laser beams relative to the surface normal of the working plane 30 is the same at every point on the working plane 30. The problem with this optical arrangement is that the laser lines provided by such an arrangement cannot be stitched in a meaningful way. Due to the size of the lenses in comparison to the laser line imaged on the working plane, a laser line with homogeneous intensity cannot be achieved, even if several such optical arrangements are placed directly next to one another. Therefore, such an optical arrangement is not suitable for SLA applications, for example.

2B also shows an optical arrangement from the prior art. Like the optical arrangement shown in FIG. 2A, the optical arrangement shown here also consists of a homogenizer 22 and a focusing unit 28 in the form of a lens. In principle, the structure shown in Fig. 2B differs from the structure shown in Fig. 2A only in the size of the distance a between the homogenizer 22 and the focusing unit 28. The selected distance a causes the line length of the laser beam to be along the x- Direction on the working plane 30 is longer than the extent of the focusing unit in this dimension. This means that stitching with homogeneous intensity is fundamentally possible. However, the distance a chosen in Figure 2B is such that the image produced by the lens is not telecentric. The angular spectrum of the laser beams arriving on the working plane 30 is therefore not homogeneous. Shown as an example is a point on the working plane 30 at which the angle of incidence is 0>0°, as well as a point at which the angle of incidence is 0<0°. Such an arrangement is therefore not suitable for SLA applications.

3 shows a simplified, schematic representation of several identical sources 12a, 12b, 12c and 12d and the laser beam bundles 16a, 16b, 16c and 16d generated by the sources 12a, 12b, 12c and 12d. The sources 12a, 12b, 12c and 12d generate beams 16a, 16b, 16c and 16d with a Gaussian profile in the x-axis, the beams 16a, 16b, 16c and 16d each having the same divergence. The sources 12a, 12b, 12c and 12d are arranged at equidistant distances from one another along a line along the x-axis. Due to the divergence of the laser beam bundles 16a, 16b, 16c and 16d, it occurs in the z direction (ie downstream) from a certain distance away Sources to superimpose the individual, initially separated laser beam bundles. Shown in particular are the planes E1, E2, E3 and E4 that run parallel to the x-axis, as well as (schematically) the intensity profiles of the individual beam bundles that arise in these planes along the x-axis.

In the plane E1 of the sources 12a, 12b, 12c and 12d, the individual laser beam bundles 16a, 16b, 16c and 16d are still separated from one another. This means that in this level the Gaussian profiles are clearly separated from each other. In plane E2 there is already slight overlapping of the laser beam bundles, which is expressed in the intensity curve in the y-direction in plane E2 by a superposition of the Gaussian profiles. An envelope with a fluctuating intensity curve is created. In the plane E3, the overlays are such that the intensity profile of the envelope is essentially constant along the x-direction (except at the edges). The intensity spectrum in plane E3 is therefore homogeneous. In plane E4, the overlap of the individual beam bundles is already so large that several intensity maxima arise in the envelope. This means that in plane E4 the intensity spectrum along the x-axis is not homogeneous.

At the same time, the Gaussian beams generated by the laser light sources 12a, 12b, 12c and 12c are angularly homogeneous or generate an angularly homogeneous spectrum in the respective planes E1 to E4. Overall, however, there is only a spectrum that is homogeneous in terms of angle and intensity in plane E3. This means that only level E3 would be suitable as a working level for an SLA application.

With regard to the superimposition of the individual beam bundles, with such an arrangement it is advantageous to arrange any optical arrangements or units in a plane in which the bundles are still separated, i.e. in particular in a plane (downstream of the beam) in front of the plane E2. This is the only way to ensure that the individual beam bundles can be addressed by separate subunits in the beam bundles.

As far as the extent of the overall source is concerned, ie the extent of the sources 12a, 12b, 12c and 12d in their entirety, this is (approximately) equal to the (intensity-homogeneous) line length in the plane E3. At the same time, in plane E3 the angle spectrum has the same width at every point on the long axis. 4 shows a second exemplary embodiment of the new device 10. For the basic structure of the device 10, reference is made to the first exemplary embodiment in FIG. 4 shows in particular that the device 10 has a first optical arrangement 14 in addition to the second optical arrangement 18, consisting of the transformers 24a, 24b and 24c and the homogenizers 22a, 22b and 22c as six second optical subunits 18a to 18f , consisting of a total of nine first subunits 14a, 14b, 14c, 14d, 14e, 14f, 14g, 14h and 14i. The subunits form a focusing unit in beams with respect to the short axis (SA). In other words, the first subunits 14a, 14d and 14g form a focusing unit for the laser beam bundle 16a. The first subunits 14b, 14e and 14h form a focusing unit for the laser beam 16b and the first subunits 14c, 14f and 14i form a focusing unit for the laser beam 16c. The first optical arrangement 14 is arranged downstream of the beam (ie in the z direction) behind the second optical arrangement 18 (transformers and homogonizers). In particular, in addition to the second optical arrangement 18, the first optical arrangement 14 is also located in an area in which the individual beam bundles 16a, 16b and 16c do not yet overlap. In other words, in addition to the second optical arrangement, the first optical arrangement is also located in the z-direction in front of the first distance A. Consequently, the individual optical channels, comprising the optics in the respective beam bundles 16a, 16b and 16c, can be addressed separately. In particular, if a subunit malfunctions, it is sufficient to replace the corresponding subunit. The replacement of any large optics and the associated inconveniences and costs are therefore eliminated.

[0056] In this exemplary embodiment, the first optical arrangement 14 includes a focusing unit in the respective channels, which is set up to generate a Gaussian or Tophat profile in the short axis (i.e. in the y direction), the width of which is approximately 20pm .

[0057] In the device of the exemplary embodiment shown in FIG. 4, the individual first and second subunits are (each) adjustable separately from one another in lateral and longitudinal degrees of freedom. In particular, the subunits shown can be moved (each) in the x, y and z directions. In preferred embodiments, the subunits may further be tilted in one of these directions. The line profiles resulting from the individual optical channels on the working plane 30 can thus be in can be easily manipulated and stitched into a “smooth” overall line in the working plane, ie into an overall line which is homogeneous in terms of both intensity and angle in the working plane 30.

In principle, in order to realize an angle-homogeneous spectrum in the long axis of the respective laser beam bundles and to address the individual channels with respect to the long axis, it is not necessary to subdivide the first optical arrangement 18 into a plurality of first subunits. In principle, any large optics known from the prior art can be used for this.

5A shows a first exemplary embodiment of an arrangement of beam splitters and a mirror. In particular, FIG. 5A shows a first beam splitter 26a, which separates an incoming laser beam 16 into two partial beams or partial beam bundles. While one of the two partial beam bundles is guided in the z direction, the other partial beam bundle illuminates a second beam splitter 26b, which is located behind the first beam splitter in the x direction. This in turn divides the partial beam hitting it into two further partial beams. Another partial radiator 26c further separates the incident beam bundle. The laser beam bundle emanating from the beam splitter 26c in the x direction is then deflected in the z direction by a mirror 38. This creates a divided laser beam bundle 16 'from the partial beam bundles emitted by the beam splitters 26a, 26b and 26c in the z direction and from the partial beam bundle deflected by the mirror 38. The optical arrangement shown in FIG. 5A can therefore be used in combination with a source that emits an angle-homogeneous spectrum as a second subunit for the device 10 disclosed here. In principle, the use of a beam splitter is also conceivable in the first optical arrangement 18 of the device 10. Since a beam splitter has no influence on the angular spectrum of a laser beam, it can in principle also be placed downstream behind the second optical arrangement.

5B shows a second embodiment of an arrangement of beam splitters and a mirror. In contrast to the first exemplary embodiment shown in FIG. 5A, here the beam splitter 26a is irradiated not only with a laser beam 16 from the x-direction but also with a laser beam 17 from the z-direction. This allows the intensity of the outgoing laser beam bundles 16' to be increased. The arrangement of the second exemplary embodiment can also serve as a second optical subunit for the device 10. Nevertheless, the beam splitter can be used in other optical arrangements of the device 10.

6A shows an exemplary embodiment of a transformer 24. The transformer 24 expands an incoming laser beam bundle 16 into a wider laser beam bundle 16′. In this exemplary embodiment, the transformer 24 is implemented like the transformer that is described in detail in the aforementioned WO 2018/019374 A1. Accordingly, WO 2018/019374 A1 is incorporated herein by reference in relation to the transformer. The transformer of the exemplary embodiment shown comprises a transparent (for the incoming laser beam) monolithic plate-shaped element with a front side and a back side running parallel to the front side. The front and back have a reflective coating on the inside of the element, so that the incident beam 16 experiences multiple reflections within the element (not shown here) before it expands, i.e. as a much wider laser beam 16 ', exits on the back. In the event that an angle-homogeneous laser beam bundle 16 already impinges on it, the transformer 24 can be used in the device according to the invention as the sole component of a second optical subunit. Nevertheless, it can also simply be part of a second optical subunit, which further comprises, for example, a homogenizer.

6B shows an exemplary embodiment of an arrangement of transformers 24. Four transformers 24a, 24b, 24c and 24d are arranged in a row parallel to the x-axis. From the z direction, the transformers are each illuminated with a laser beam bundle 16a, 16b, 16c or 16d. The transformer 24a converts the laser beam 16a into a beam 16a'. The laser beam bundle 16a' has a significantly larger width along the x-axis. The aspect ratio of the incoming bundle was thus changed. The transformers 24b, 24c and 24d in turn expand the laser beams 16b, 16c and 16d into the laser beams 16b', 16c' and 16d' as well. The optical assembly shown in Figure 6B may be used as part of a second optical assembly 18 for the device 10. In particular, the transformers enable a homogenizer downstream of the beam to receive broad illumination, thus enabling easy stitching of adjacent laser lines. It is also conceivable that the transformers shown serve alone as a second optical arrangement 18. A homogeneous angular distribution on the working plane is But then only possible if the incoming laser beam bundles 16a, 16b, 16c and 16d are already angularly homogeneous.

7A shows a first embodiment of a homogenizer 22. In this embodiment, the homogenizer 22 includes a microlens array. A laser beam bundle 16 on the input side is separated into equidistantly separated beams or beam bundles of the same divergence via the microlens array.

7B shows a second exemplary embodiment of a homogenizer 22. In this exemplary embodiment, the (imaging) homogenizer 22 comprises two microlens arrays. The first microlens array, viewed downstream, is used to split the incident beam into multiple beams, while the second microlens array (viewed downstream) causes the images of the individual beams of the first array to be superimposed and projected onto the working plane (not shown). As with the homogenizer shown in FIG. 7B, an input-side laser beam bundle 16 is separated into equidistantly separated beams of the same divergence.

Claims

Claims Device (10) for generating a defined laser line on a working plane (30), with a plurality of laser light sources (12a, 12b, 12c), each of which is set up to generate a laser beam bundle (16a, 16b, 16c) of predefined divergence, the laser beam bundles (16a, 16b, 16c) define a beam direction (z) which intersects the working plane (30), and are designed to overlap at a first distance (A) in front of the working plane (30), and wherein the laser beam bundles (16a , 16b, 16c) in the area of the working plane (30) have a beam profile which has a long axis (LA) with a long-axis beam width and a short axis (SA) with a short-axis beam width perpendicular to the beam direction (z), a first optical arrangement ( 14), which is set up to generate a predefined beam profile in the short axis (SA) in the working plane (30), characterized in that the device (10) further comprises a second optical arrangement (18), which has several of each other has separate second subunits (18a, 18b, 18c), which are designed to generate an angularly homogeneous beam profile in the long axis (LA) in the working plane (30). Device (10) according to claim 1, characterized in that the laser beam bundles (16a, 16b, 16c) generated by different laser light sources (12a, 12b, 12c) do not pass through a common optical element which causes the laser beam bundles (16a, 16b, 16c) to overlap. contributes. Device (10) according to claim 1 or 2, characterized in that the second optical arrangement (14) is arranged in the beam path of the plurality of laser beam bundles (16a, 16b, 16c) in the beam direction in front of the first distance (A). Device (10) according to one of claims 1 to 3, characterized in that the laser light sources (12a, 12b, 12c) are arranged at an equidistant distance from one another and / or that the second subunits (18a, 18b, 18c) are at an equidistant distance are arranged to each other. Device (10) according to one of claims 1 to 4, characterized in that the second subunits (18a, 18b, 18c) can be displaced and/or inclined parallel and/or perpendicular to the working plane (30). Device (10) according to one of claims 1 to 5, characterized in that the second subunits (18a, 18b, 18c) comprise a homogenizer (22) which is designed to homogenize laser beams of the laser beam bundle (16) in the long axis, particularly angularly homogeneous. Device (10) according to one of claims 1 to 6, characterized in that the second subunits (18a, 18b, 18c) comprise a transformer (24) which is designed to move one of the laser beam bundles (16a, 16b, 16c) along the long axis (LA). Device (10) according to one of claims 1 to 7, characterized in that the second subunits (18a, 18b, 18c) comprise a beam splitter (26) which is designed to split one of the laser beam bundles (16a, 16b, 16c) into several Split partial beams. Device (10) according to one of claims 1 to 8, characterized in that the first optical arrangement (14) has a plurality of separate first subunits (14a, 14b, 14c). Device (10) according to one of claims 1 to 9, characterized in that only one or more further optical arrangements are arranged between the second optical arrangement (18) and the working plane (30), which have no influence on the angular spectrum of the laser beam bundles (16a , 16b, 16c) in the long axis (LA). Device (10) according to one of claims 1 to 10, characterized in that the laser light sources (12a, 12b) are UV sources, in particular UV sources whose laser beam bundles (16a, 16b) each have a beam profile of the same intensity.