Apparatus for generating a defined laser irradiation on a work plane

Abstract

An apparatus for generating a defined laser illumination (12) on a work plane (14) has a laser light source (20) that generates a raw laser beam (22). An optical assembly (24) receives the raw laser beam (22) and shapes it into an illumination beam (26) along an optical axis (40). The illumination beam (26) defines a beam direction (28) that intersects the work plane (14). The illumination beam (26) has a beam profile (42; 42') in a region of the work plane (14) that has a major axis (44) perpendicular to the beam direction (28) with a major axis beam width and a minor axis (46) with a minor axis beam width. The optical assembly (24) includes a beam transformer (30) with an exit aperture, a first set of optical elements (56, 60, 62, 64) for beam shaping on the major axis, and a second set of optical elements (34, 36, 38) for beam shaping on the minor axis. The beam transformer (30) widens the raw laser beam (22) on the major axis to generate a widened raw laser beam. The first set of optical elements (56, 60, 62, 64) includes a homogenizer (56) that homogenizes the widened raw laser beam on the major axis. The second set of optical elements (34, 36, 38) includes at least one lens (38) that images the exit aperture of the beam transformer (30) into the work plane. The first set of optical elements (56, 60, 62, 64) generates an intermediate image (66) behind the homogenizer (56) and further implements an imaging optical unit that images the intermediate image (66) into the work plane (14).

Description

Technical Field

[0001] This invention relates to an apparatus for generating a defined laser irradiation on a working plane. The apparatus includes a laser source configured to generate a raw laser beam and an optical assembly for receiving the raw laser beam and shaping it into an irradiation beam along an optical axis. The irradiation beam defines a beam direction intersecting the working plane and has a beam profile in a region of the working plane. The beam profile has a major axis and a minor axis perpendicular to the beam direction. The major axis has a major axis beam width, and the minor axis has a minor axis beam width. The optical assembly includes a beam converter with an exit aperture, a first set of optical elements for beam shaping along the major axis, and a second set of optical elements for beam shaping along the minor axis. The beam converter broadens the raw laser beam along the major axis to generate a broadened raw laser beam. The first set of optical elements includes a homogenizer that homogenizes the broadened raw laser beam along the major axis, and the second set of optical elements includes at least one lens that images the exit aperture of the beam converter onto the working plane. Background Technology

[0002] For example, such a device is described in WO 2018 / 019374 A1.

[0003] Specifically, linear laser irradiation from such a device can be used to process workpieces. For example, the workpiece can be a plastic material on a glass plate used as a carrier material. Specifically, the plastic material can be a film on which organic light-emitting diodes (known as OLEDs) and / or thin-film transistors are produced. OLED films are increasingly used in displays in smartphones, tablet PCs, televisions, and other devices with screen displays. After the electronic structure has been produced, the film must be separated from the glass carrier. Advantageously, this can be done using laser irradiation in the form of a fine laser line, which moves relative to the glass plate at a defined speed and in the process breaks the adhesive bond between the film and the glass plate. In practice, this application is often referred to as LLO or laser lift-off.

[0004] Another application of using a defined laser line to irradiate a workpiece can be the row-by-row melting of amorphous silicon on a carrier plate. In this case, the laser line also moves relative to the workpiece surface at a defined speed. Due to melting, relatively inexpensive amorphous silicon can be converted into more advanced polycrystalline silicon. In practice, this application is often referred to as solid-state laser annealing or SLA.

[0005] In a working plane, such applications require a laser line that is as long as possible in one direction to detect the widest possible work area, and that the laser line is relatively short in other directions to provide the energy density required for the corresponding process. Accordingly, long, thin laser lines with a large aspect ratio are desirable, for example, a linewidth of 10 μm and a length of 100 mm parallel to the working plane. The direction in which the laser line extends is generally referred to as the major axis of the so-called beam profile, and the linewidth is referred to as the minor axis of the so-called beam profile. Typically, the laser line should have a defined intensity distribution along both axes. For example, it is desirable for the laser line to have an intensity distribution that is as rectangular or trapezoidal as possible along the major axis, which may be advantageous when multiple such laser lines should be placed adjacent to each other to form a longer overall line. Depending on the application, a rectangular intensity distribution (so-called top hat profile), a Gaussian distribution, or any other intensity distribution is desired along the minor axis.

[0006] The opening citation, WO 2018 / 019374 A1, discloses a device of the type described in the opening and includes numerous details relating to the elements of the optical components. The optical components include a collimator for collimating the raw laser beam, a beam converter, a homogenizer, and a focusing stage. The beam converter receives the collimated raw beam and broadens it along its long axis. In principle, the beam converter can also receive multiple raw laser beams from multiple laser sources and combine them to form a broadened laser beam with higher power. The homogenizer generates the desired beam profile along its long axis. The focusing stage focuses the shaped laser beam at a defined position within a working plane region. This known device is suitable for both LLO and SLA applications. However, this device is not ideal for some specific LLO applications (e.g., when separating so-called μLEDs). In such cases, it is desirable to provide multiple individual top-hat-shaped intensity distributions. For example, an arrangement in which multiple individual top-hat-shaped intensity distributions are equidistant along a line might be desirable. The device with WO 2018 / 019374 A1 does not provide this information. Summary of the Invention

[0007] In view of this, the primary objective of the present invention is to provide an alternative device of the opening descriptive type, by which a defined laser line with a large aspect ratio can be generated cost-effectively. A secondary objective of the present invention is to provide an opening descriptive type device that is cost-effective and flexible enough to allow for multiple different irradiation patterns on the working plane.

[0008] In this context, according to one aspect of the invention, a device of the type described in the opening section is proposed, in which a first set of optical elements generates an intermediate image behind a homogenizer and further implements an imaging optical unit that images the intermediate image onto a working plane.

[0009] The first set of optical elements primarily exhibits optical refractive power along the long axis. Therefore, these optical elements primarily influence the beam profile along the long axis. In contrast, the second set of optical elements primarily exhibits optical refractive power along the short axis. Therefore, these optical elements primarily influence the beam profile along the short axis. In embodiments, the optical elements may each include cylindrical elements, particularly cylindrical lenses and / or cylindrical mirrors, each arranged such that they exhibit optical refractive power either along the long axis or the short axis. Therefore, in a preferred embodiment, beam shaping along the long axis and beam shaping along the short axis are separated, allowing beam shaping along the long axis and beam shaping along the short axis to be considered separately. This allows the intensity distribution of the beam profile to be sized and optimized largely separately along the long axis and the short axis. As a result, the novel device achieves defined laser illumination with an aspect ratio (the ratio of the beam profile's extension along the long axis to its extension along the short axis), for example, greater than 1000.

[0010] The exit aperture of the beam converter is a light-transmitting opening at the output end of the beam converter through which the broadened laser beam exits and is fed to the homogenizer. In some embodiments, the exit aperture may have an opening of approximately 1 mm on the minor axis, and more generally an effective opening between 0.5 mm and 10 mm relative to the minor axis. A second set of optics is capable of imaging this exit aperture in a reduced manner onto the working plane and is capable of generating a laser line with a very small linewidth and a top-hat-shaped intensity distribution on the minor axis. However, this reduced minor-axis imaging requires a relatively long path length along the optical axis. The first set of optics generates an intermediate image behind the homogenizer (as seen along the optical axis) and images this intermediate image onto the working plane. In a preferred embodiment, the first set of optics includes an imaging homogenizer that generates a major-axis beam profile in a defined plane along the optical axis. This plane serves as the intermediate image plane. The major-axis beam profile generated in the intermediate image plane is imaged onto the working plane by means of additional optics in the first set of optics. In some embodiments, the equalizer may include one or more microlens arrays along the optical axis, and the intermediate image is obtained by superimposing the multiple lens apertures of the first microlens array. More generally, the first set of optical elements generates an intermediate image of the long-axis beam profile at the output side of the equalizer by means of the equalizer, and this intermediate image is imaged onto the working plane by means of other optical elements in the first set of optical elements. This (additional) imaging can extend the relatively short extension of the long-axis imaging relative to the short-axis imaging to such an extent that the two image representations coincide in the working plane. As a result, the novel device efficiently achieves a large aspect ratio.

[0011] Therefore, the novel device can achieve a favorable top-hat-shaped intensity distribution on the short axis by reducing the aperture diameter, which can be >1 mm relative to the short axis. Such an aperture can be manufactured cost-effectively. However, to obtain a small linewidth, for example 10 μm, and further to make the homogenizer cost-effective in terms of manufacturing technology, it is advantageous to bridge the path length by performing multiple imaging operations on the long axis. The novel device achieves this by imaging intermediate images.

[0012] Furthermore, the intermediate image plane can be advantageously used to place the comb aperture, allowing for optional segmentation of the beam profile along the long axis. If necessary, this simplifies the design of novel devices to generate multiple individual illumination spots along the long axis. Thus, the structure of the novel device provides variability along the short axis (achieved by varying the linewidth through the exit aperture of the beam converter) and variability along the long axis (achieved by segmenting the laser line through a suitable aperture). These objectives are achieved in a simple and cost-effective manner.

[0013] In a preferred embodiment of the invention, the first set of optical elements further includes a first mask arranged in the region of the intermediate image.

[0014] In some embodiments, the first mask may be a comb-shaped aperture having a plurality of aperture holes arranged adjacent to each other. For example, a series of equidistant apertures. In another embodiment, the mask may include a mirror segmented with alternating high-reflectivity and anti-reflectivity layers. The apertures or alternating layers can advantageously segment the beam profile into individual illumination spots along the long axis. In principle, the distribution of the transparent or reflective regions and the opaque or non-reflective regions of the first mask can be freely chosen. In this configuration, the novel device advantageously uses a variable basic concept in a cost-effective manner to segment the beam profile along the long axis. This configuration is particularly advantageous for LLO applications using separated μLEDs or for laser-induced forward transfer (LIFT) (i.e., transferring separated μLEDs to another display).

[0015] In another configuration, the first mask is constructed as a replacement (Austauschteil).

[0016] In this configuration, a user of the novel device can optionally place or remove the first mask in or from the region of the intermediate image at the output of the equalizer. In some embodiments, the first mask can be held onto a carrier body that can be optionally moved in or out of the beam path of the optical assembly. In these embodiments, the first mask can be held in a translational and / or rotational manner and thus optionally pushed into and / or swung into the beam path. This configuration expands the application range of the novel device.

[0017] In another configuration, the second set of optical elements includes at least one second mask.

[0018] In this configuration, the novel device has a mask that allows for a simple and efficient acquisition of the desired intensity distribution of the beam profile along the minor axis. In some embodiments, a top hat-shaped profile along the minor axis is achieved by means of a second mask. Preferably, the aperture of the second mask is >1 mm, as this allows for a cost-effective implementation.

[0019] In another configuration, the at least one second mask is arranged in the region of the beam converter.

[0020] Placing the second mask in the region of the beam transformer allows for efficient realization of the desired intensity distribution on the short axis, particularly a top hat-shaped profile with steep sides (Flanke).

[0021] In another configuration, a second set of optical elements generates another intermediate image, with at least one second mask arranged in the region of this other intermediate image. Preferably, this other intermediate image is an intermediate image of the beam converter.

[0022] This configuration offers a favorable and variable alternative, especially when installation space is limited in the area of ​​the beam converter.

[0023] In another configuration, the at least one second mask is constructed as a replacement.

[0024] In this configuration, a user of the novel device can optionally place or remove the second mask in or from the beam path. In some embodiments, the second mask can be held onto a carrier body, which can be optionally moved in or out of the beam path of the optical assembly. The second mask can be held in a translational and / or rotational manner and thus optionally pushed into and / or swung into the beam path. This configuration expands the applicability of the novel device by rapidly and individually adapting the beam profile along its minor axis.

[0025] In another configuration, the imaging optical unit includes a folding optical unit (Faltungsoptik) having at least one mirror element, preferably having at least two mirror elements that enable multiple folding.

[0026] In this configuration, the imaging optics unit may specifically include one or more cylindrical mirrors that fold multiple times along the long axis of the beam path. This configuration achieves a compact new device while retaining the aforementioned advantages.

[0027] In another configuration, the second set of optical elements includes a projection lens arranged along the optical axis as close as possible to the working plane, and a folding optical unit arranged along the optical axis between the homogenizer and the projection lens.

[0028] In this configuration, the first set of optical elements is positioned to some extent between the second set of optical elements along the optical axis. This arrangement also contributes to a compact implementation. Furthermore, this arrangement achieves high beam quality along the minor axis.

[0029] In another configuration, the beam profile has a top hat-shaped intensity distribution along the short axis beam width.

[0030] The top hat-shaped intensity distribution is particularly advantageous for releasing μLEDs and other individual components.

[0031] It should be understood that the features described above and those explained below can be used not only in the specified combinations, but also in other combinations or individually, without departing from the scope of the invention. Attached Figure Description

[0032] Embodiments of the invention are illustrated in the accompanying drawings, and are explained in more detail in the following description. In the drawings:

[0033] Figure 1a A simplified schematic diagram of the long-axis beam path of an embodiment of the novel device is shown.

[0034] Figure 1b It shows Figure 1a A simplified schematic illustration of the short-axis beam path of an embodiment.

[0035] Figure 2 A simplified illustration of the beam profile according to an embodiment of the novel device is shown.

[0036] Figure 3 A plan view showing an advantageous beam profile according to some embodiments of the novel device is shown.

[0037] Figure 4 It shows Figure 1a and Figure 1bThe embodiments provide long-axis and short-axis beam paths and further details.

[0038] Figures 5a to 5c An exemplary intensity distribution according to an embodiment of the novel device is shown.

[0039] Figure 6 Details of a preferred embodiment of the novel device are shown, wherein the mirror is folded along the long axis beam path, and

[0040] Figure 7 It shows Figure 6 A schematic diagram of a folded mirror. Specific Implementation

[0041] The overall implementation of the new equipment is as follows Figure 1a and Figure 1b The reference numeral 10 indicates this. In this case, the device 10 generates a laser line 12 in the area of ​​the working plane 14 to process the workpiece 16 placed in the area of ​​the working plane 14. In this case, the laser line 12 extends in the x-axis direction and the linewidth is here regarded as being in the y-axis direction. Accordingly, the x-axis is referred to below as the line formed in the working plane 14 (see Figure 10). Figure 2 The major axis of the beam profile on the y-axis is represented by the y-axis, and the minor axis is represented by the y-axis.

[0042] In some embodiments, workpiece 16 may include a film layer having OLEDs disposed on a glass plate and intended to be separated from the glass plate by means of laser line 12. To process workpiece 16, laser line 12 may be moved relative to workpiece 16 in the direction of arrow 18.

[0043] The device 10 includes a laser source 20, which may be, for example, a solid-state laser that generates laser light in the infrared or UV range. For example, the laser source 20 may include an Nd:YAG laser with a wavelength on the order of 1030 nm. In other examples, the laser source 20 may include a diode laser, an excimer laser, or a solid-state laser, which generate laser light with wavelengths between 150 nm and 360 nm, between 500 nm and 530 nm, or between 900 nm and 1070 nm, respectively.

[0044] Laser source 20 generates a raw laser beam 22, which can be coupled into optical assembly 24, for example, via an optical fiber. The raw laser beam 22 is shaped by optical assembly 24 into an illumination beam 26, which defines a beam direction 28. The beam direction 28 intersects the working plane 14.

[0045] Optical component 24 includes a beam converter 30 that broadens the original laser beam 22 in the x-direction (corresponding to the major axis). In a preferred embodiment, beam converter 30 may be implemented as described in detail in WO 2018 / 019374 A1 cited at the outset. Therefore, WO 2018 / 019374 A1 is incorporated herein by reference with respect to the beam converter and homogenizer described below.

[0046] Specifically, the beam converter 30 may include a transparent, monolithic planar element having front and rear sides that are substantially parallel to each other. This planar element may be arranged at an acute angle to the original laser beam 22, such as... Figure 1b As described above, both the front and rear sides may have reflective coatings, causing the original laser beam 22, input to the inclined planar element on the front side, to undergo multiple reflections within the planar element before exiting at the rear side of the planar element and broadening in the x-axis direction. In other embodiments, the beam converter may be implemented as an aperture or by means of an aperture.

[0047] Optical assembly 24 includes a long-axis optical unit 32, which is illustrated only schematically herein, and shapes the broadened original laser beam along its long axis and images the shaped original laser beam onto the working plane 14. Specifically, the long-axis optical unit 32 may include one or more microlens arrays (not depicted herein) and one or more lenses having optical refractive power primarily along the long axis. The microlens arrays and the one or more lenses may be configured as cylindrical lenses whose cylindrical axes extend in the y-direction and these cylindrical lenses form an imaging equalizer that equalizes the original laser beam 22 along the long axis to obtain a defined, typically top-hat-shaped intensity distribution along the long axis.

[0048] The optical assembly 24 further includes a plurality of optical elements 34, 36, and 38 that shape the broadened original laser beam along its minor axis and focus the shaped original laser beam onto the working plane 14. The optical elements 34, 36, and 38 are arranged along the optical axis 40 and, in this case, include a first lens 34 and a second lens 36, which together form the telescope assembly. In this case, the optical element 38 is an objective lens having one or more lens elements that focuses the irradiated beam 26 onto the working plane 14 along its minor axis.

[0049] The optical assembly 24 is configured to generate an illumination beam 26 having a defined beam profile 42 in the region of the working plane 14. Figure 2An idealized representation of this beam profile 42 is shown. The beam profile 42 describes the laser radiation intensity I on the working plane 14 according to its corresponding positions along the x-axis and y-axis. As illustrated, the beam profile 42 has a major axis 44 and a minor axis 46, with the major axis having a major axis beam width in the x-direction and the minor axis having a minor axis beam width in the y-direction. The minor axis beam width 46 can be described, for example, as the width between half-maximum width at half maximum (FWHM) or 90% of the intensity values ​​(90% peak full width, FW@90%). In this case, the beam profile 42 has a top hat-shaped profile on the minor axis, having a first side 48, a second side 50, and a largely flat plateau 52 between the first side 48 and the second side 50. In principle, the beam profile 42, particularly on the minor axis 46, can have a different intensity distribution, such as a Gaussian intensity distribution.

[0050] As in Figure 2 The idealized beam profile 42 is desirable for some applications (e.g., separating a relatively large OLED film from a carrier substrate). In contrast, for other applications, it may be desirable to divide the beam profile 42 into multiple spaced-apart illumination spots 54a, 54b, 54c, etc. Figure 3 The segmented beam profile 42' is shown from above in a schematic plan view of the working plane 14. In a preferred embodiment, the optical components can generate the beam profile 42', wherein the illumination spots 54a, 54b, 54c... are equidistantly distributed along the long axis. In this case, preferably, the long axis extends on the order of 100 mm. Advantageously, in this case, the illumination spots 54a, 54b, 54c... each have a generally rectangular footprint, for example, 20 μm x 20 μm, and can be spaced apart from each other, for example, by 100 μm. Preferably, in this case, the illumination spots 54a, 54b, 54c... each have a top hat-shaped profile along the short axis. This segmented beam profile 42' is advantageous for LLO or LIFT applications, where multiple μLEDs need to be separated from a carrier plate. The novel device 10 readily and efficiently achieves this desired beam profile 42 in some embodiments, as further referenced below. Figures 4 to 7 Explanatory. Here, the same reference numerals denote the same elements as before.

[0051] Figure 4 It shows Figure 1a and Figure 1bThe long-axis optical unit 32 has further details. The long-axis optical unit 32 includes a homogenizer 56, which in some embodiments may include a first microlens array 58a and a second microlens array 58b, arranged at a defined distance from each other along the optical axis. In this case, the first optical element 60, the second optical element 62, and the third optical element 64 are arranged along a further path of the beam path. In some embodiments, one or more of elements 60, 62, and 64 may be Fourier lenses. In other embodiments, elements 60, 62, and 64 may be mirror elements, particularly cylindrical mirrors, as referenced below. Figure 6 and Figure 7 Explanation.

[0052] In this configuration, homogenizer 56 and optical elements 60, 62, and 64 form a first set of optical elements and shape the broadened original laser beam along the long axis. In contrast, optical elements 34, 36, and 38 form a second set of optical elements that shape the broadened original laser beam along the short axis. As explained above, in this configuration, optical element 60 generates an intermediate image 66 of the long-axis beam profile. The intermediate image 66 is imaged onto the working plane 14 by means of optical elements 62 and 64. Advantageously, in this configuration, a (first) mask 68 can be arranged in the region of the intermediate image 66. In particular, the mask 68 can be a comb-shaped aperture having multiple apertures arranged adjacent to each other. Using such a mask 68 allows for the shaping of the beam profile 42' ( Figure 3 Perform simple and efficient segmentation to obtain data based on... Figure 3 The mutually spaced illumination spots 54a, 54b, 54c...

[0053] Alternatively or as a supplement, in this case, another mask 70 may be arranged in the region of beam converter 30 and / or in the region of intermediate image 71 of beam converter 30. This other mask 70 may have an aperture >1 mm relative to the short-axis beam path of optical elements 34, 36, 38. With the aid of the mask 70, a top-hat-shaped intensity distribution with very steep sides and a largely flat top can be easily and efficiently obtained on the short axis. In this case, the long path length on the short-axis beam path advantageously reduces the imaging of the aperture on the working plane 14, in order to obtain illumination spots 54a, 54b, 54c… with a size of 20 μm on the short axis, which… Figure 3 The following is an example.

[0054] For example, Figure 5a The intensity distribution of the beam profiles 42, 42' relative to the minor axis is shown, as can be obtained by means of the aforementioned mask 70. Figure 5bThe intensity distribution of the beam profile 42 relative to the major axis is shown without the mask 68. Figure 5c The diagram shows an intensity distribution segmented along the major axis using the aforementioned mask 68, comprising two mutually spaced-apart line portions 72a and 72b. To obtain according to... Figure 5c The intensity distribution of the line portions 72a and 72b spaced apart is such that the mask 68 can have two spaced-apart apertures in the region of the intermediate image 66. Different masks 68 can be used (e.g., with...). Figure 3 (As shown) the beam profile is divided in different ways 42.

[0055] Figure 6 An optical assembly 24 of one embodiment is shown with further details. In addition to the previously mentioned optical elements 34, 36, 38, each in this embodiment of the short-axis optical unit as a cylindrical lens, and optical elements 60, 62, 64, each in this embodiment of the long-axis optical unit as a cylindrical lens, the optical assembly 24 in this embodiment also includes two additional lenses 74, 76 forming a telescope assembly. Lenses 74, 76 focus the raw laser beam onto the entrance aperture of the beam converter 30. Lenses 34, 36, together forming another telescope, are arranged at the output of the beam converter 30. In some embodiments, an optional spatial filter 78 may be arranged between lenses 34, 36, for example, to reduce possible diffraction artifacts. In this case, reference numeral 80 indicates an optional deflector that deflects the broadened raw beam to the equalizer 56. Advantageously, the deflector 80 contributes to a compact structure of the optical assembly 24. In this configuration, behind the homogenizer 56 (which may also include two microlens arrays 58a, 58b), the homogenized laser beam is guided to mirrors 60, 62 by means of another deflecting mirror (hidden in this case). In this configuration, mirrors 60, 62 reflect the laser beam multiple times, such as... Figure 7 The image is shown in a simplified manner, and an intermediate image is generated in the area of ​​mask 68. The intermediate image through the mask is guided to projection lens 38 by means of mirrors 60, 62, and 64. Projection optics unit 38 focuses the broadened laser beam as illumination beam 26 onto the working plane and generates laser line 12 therein, or, depending on mask 68, generates multiple illumination spots that can be distributed along the long axis. Here, the carrier is illustrated by reference numeral 82, and this carrier can move mask 68 into or out of the beam path according to the desired application.

Claims

1. An apparatus for generating a defined laser irradiation (12) on a working plane (14), the apparatus having a laser source (20) configured to generate a raw laser beam (22), and an optical assembly (24) for receiving the raw laser beam (22) and shaping the raw laser beam into an irradiation beam (26) along an optical axis (40), wherein, The irradiation beam (26) defines a beam direction (28) intersecting the working plane (14), wherein the irradiation beam (26) has a beam profile (42; 42') in a region of the working plane (14), the beam profile having a major axis (44) and a minor axis (46) perpendicular to the beam direction (28), the major axis having a major axis beam width and the minor axis having a minor axis beam width, wherein the optical component (24) includes a beam converter (30) having an exit aperture. The beam converter (30) comprises a first set of optical elements (56, 60, 62, 64) for beam shaping on the long axis and a second set of optical elements (34, 36, 38) for beam shaping on the short axis, wherein the beam converter (30) broadens the original laser beam (22) on the long axis to generate a broadened original laser beam, wherein the first set of optical elements (56, 60, 62, 64) includes a homogenizer (56) on the long axis. The broadened original laser beam is homogenized, wherein the second set of optical elements (34, 36, 38) includes at least one lens (38) that images the exit aperture of the beam converter (30) onto the working plane, characterized in that the first set of optical elements (56, 60, 62, 64) generates an intermediate image (66) behind the homogenizer (56) and further implements an imaging optical unit that images the intermediate image (66) onto the working plane (14), wherein the first set of optical elements (56, 60, 62, 64) further includes a first mask (68) arranged in the region of the intermediate image (66), wherein the first mask (68) is a comb aperture having a plurality of apertures arranged adjacent to each other, the comb aperture generating individual illumination spots (54a, 54b, 54c) in the region of the working plane (14).

2. The device according to claim 1, characterized in that, The first mask (68) is constructed as a replacement.

3. The device according to claim 1 or 2, characterized in that, The second set of optical elements (34, 36, 38) includes at least one second mask (70).

4. The device according to claim 3, characterized in that, The at least one second mask (70) is arranged in the region of the beam converter (30).

5. The device according to claim 3, characterized in that, The second set of optical elements (34, 36, 38) generates another intermediate image (71), wherein the at least one second mask is arranged in the region of the other intermediate image (71).

6. The device according to claim 3, characterized in that, The at least one second mask (70) is constructed as a replacement.

7. The device according to claim 1 or 2, characterized in that, The imaging optical unit includes a folding optical unit, which has at least one mirror element.

8. The device according to claim 7, characterized in that, The folding optical unit has at least two mirror elements, which enable multiple folding operations.

9. The device according to claim 7, characterized in that, The second set of optical elements (34, 36, 38) includes a projection lens (38) arranged along the optical axis (40) closest to the working plane (14), wherein the folding optical unit is arranged along the optical axis (40) between the homogenizer (56) and the projection lens (38).

10. The device according to claim 1 or 2, characterized in that, The beam profile (42; 42') has a top hat-shaped intensity distribution (48, 50, 52) over the short axis beam width.

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