Abstract
A laser-machining device comprising a laser-radiation source to generate a laser beam and emit it along an optical path; a beam-splitting unit downstream of the laser-radiation source designed to split the laser beam into a bundle of partial beams; an optical control unit downstream of the beam-splitting unit comprising a reflective optical functional unit formed by an array of reflective microscanners, wherein the optical control unit is designed to select any desired number of partial beams in any desired spatial combination from the bundle of partial beams and direct them onto a workpiece, and to position and/or move at least one of those partial beams within a specified partial-beam scanning region of the respective partial beam using the microscanner of the array of microscanners assigned to the respective partial beam, and methods for laser machining a workpiece.
Claims
1. A laser processing device comprising: a. a laser radiation source (3) configured to generate a laser beam (L) and emit the laser beam (L) along an optical path (4) in a direction of a workpiece (2); b. a beam splitting unit (5) located downstream of the laser radiation source (3) in said beam direction and configured to split the laser beam (L) into a bundle of partial beams (T); and c. an optical control unit located downstream of the beam splitting unit (5) in the beam direction and comprising a reflective optical functional unit (8) including an array (14) of reflective microscanners (15), the optical control unit configured to select from the bundle of partial beams (T) an arbitrary number of partial beams in an arbitrary spatial combination and direct them towards the workpiece (2), and to position and/or move, within a predetermined partial beam scanning region (S.sub.T) of a respective partial beam (T), at least one, of the partial beams (T) directed towards the workpiece (2) using a microscanner (15) of the array (14) of microscanners (15) assigned to the respective partial beam (T).
2. (canceled)
3. The laser processing device according to claim 1, further including an optical functional unit (7) located between the beam splitting unit (5) and the reflective optical functional unit (8) and comprising a group of optical functional elements (10, 11) located one behind the other.
4. The laser processing device according to claim 3, wherein the group of optical functional elements (10, 11) located one behind the other comprises: a. a focusing unit (10) comprising one or several lenses, lens systems, mirrors located one behind the other, and/or any combination thereof, b. a lens array (11) of lenses (12) spaced apart from the focusing unit (10).
5. The laser processing device according to claim 4, configured so that the partial beams (T) defining the bundle of partial beams (T) pass through the focusing unit (10) and the lens array (11), along a first beam track until being reflected at the reflective optical functional unit (8) and, subsequent to being reflected at the reflective optical functional unit (8), at least some of the partial beams (T) reflected thereby pass, along a second beam track, through the optical functional unit (7), namely the lens array (11) and the focusing unit (10).
6. The laser processing device according to claim 5, configured so that each partial beam (T) defining the bundle of partial beams (T) passes along the first beam track through a lens (12) of the lens array (11) assigned to the respective partial beam (T), and at least some of the partial beams (T) reflected at the reflective optical functional unit (8) pass along the second beam track through a lens (12) of the lens array (11) assigned to the respective partial beam (T).
7. (canceled)
8. The laser processing device according to claim 6, further including a beam selecting unit (16) configured to deflect or absorb a predetermined number of partial beams (T) so that the deflected or absorbed partial beams (T) do not hit the workpiece (2).
9-15. (canceled)
16. The laser processing device according to claim 4, wherein the lens array (11) comprises a lateral assembly of lenses (12) or lens system.
17. The laser processing device according to claim 1, wherein each respective partial beam (T) is reflected by a respective microscanner (15).
18-20. (canceled)
21. The laser processing device according to claim 5, configured so that the partial beams (T) reflected at the microscanners (15) pass through the lens array (11) along the second beam track, wherein a respective partial beam (T), along the first beam track, passes through a lens (12) of the lens array (11) located adjacent to a lens (12) of the lens array (11) through which the partial beam (T) passes along the second beam track.
22-24. (canceled)
25. The laser processing device according to claim 5, further including a mirror device (42) located between the lens array (11) and the microscanners (15) and configured to deflect respective partial beams (T) passing through the lens array (11) along the first beam track in a direction of one of the microscanners (15), and to direct the respective partial beams (T) reflected at the microscanners (15) in a direction of the lens array (11) along the second beam track.
26. The laser processing device according to claim 25, wherein the mirror device (42) has a plurality of mirror surfaces (43), wherein each mirror surface (43) is configured to deflect a partial beam (T) passing through the lens array (11) along the first beam track in a direction of one of the microscanners (15), and to deflect a partial beam (T) reflected at one of the microscanners (15) in a direction of the lens array (11) along the second beam track.
27. (canceled)
28. The laser processing device according to claim 16, wherein the lateral assembly of lenses (12) or lens systems are located in a common lens plane (19) and the microscanners (15) are located among a plurality of different planes, wherein the different planes are each situated at an angle to the lens plane (19).
29. The laser processing device according to claim 25, wherein the mirror device (42) comprises a plurality of mirrors (44), wherein a first number of the mirrors (44) is located in a first mirror plane (S1) and a second number of the mirrors (44) in a second mirror plane (S2).
30. The laser processing device according to claim 29, wherein the mirrors (44) located in the mirror planes (S1, S2) are oriented at an angle to the mirror planes (S1, S2).
31. The laser processing device according to claim 29, wherein each mirror (44) of the mirror device is configured to deflect a partial beam (T) passing through the lens array (11) along the first beam track in a direction of one of the microscanners (15), and to deflect a partial beam (T) reflected at one of the microscanners (15) in a direction of the lens array (11) along the second beam track.
32. A method comprising: laser-processing a workpiece (2) at predetermined processing sites (1) using a laser processing device, wherein the laser processing device comprises a. a laser radiation source (3) configured to generate a laser beam (L) and emit the laser beam (L) along an optical path (4) in a direction of the workpiece (2); b. a beam splitting unit (5) located downstream of the laser radiation source (3) in said beam direction and configured to split the laser beam (L) into a bundle of partial beams (T); and c. an optical control unit located downstream of the beam splitting unit (5) in the beam direction and comprising a reflective optical functional unit (8) including an array (14) of reflective microscanners (15), the optical control unit configured to select from the bundle of partial beams (T) an arbitrary number of partial beams in an arbitrary spatial combination and direct them towards the workpiece (2), and to position and/or move, within a predetermined partial beam scanning region (S.sub.T) of a respective partial beam (T), at least one, of the partial beams (T) directed towards the workpiece (2) using a microscanner (15) of the array (14) of microscanners (15) assigned to the respective partial beam (T) wherein the method further comprises generating a laser beam (L) with the laser radiation source (3), and subsequent thereto, beam splitting the laser beam (L) into a bundle of partial beams (T), directing a predetermined number of partial beams (T) of the bundle of partial beams (T) in an arbitrary spatial combination towards the workpiece (2) at a predetermined number of sites using the optical control unit (6), and positioning and/or moving the predetermined number of partial beams (T) directed towards the workpiece (2) within a predetermined partial beam scanning region (S.sub.T).
33. The method according to claim 32, further including, prior to the positioning and/or moving step, rough positioning the predetermined number of partial beams (T) directed towards the workpiece (2) at the predetermined number of sites by placing the workpiece (2) in a workpiece holder and a. positioning the workpiece (2) relative to the laser processing device, or b. positioning the partial beams (T), which are directed towards the workpiece (2) and located within a master scanning region (SM), relative to the workpiece (2) using a beam positioning unit (9), or c. positioning the workpiece (2) relative to the laser processing device and the partial beams (T) directed towards the workpiece (2) and located within a master scanning region (S.sub.M) with a beam positioning unit (9).
34. The method according to claim 33, further including, subsequent to the rough positioning and the positioning and/or moving steps, performing an individual scanning movement of at least some of the predetermined number of the partial beams using the optical control unit.
35. The method according to claim 33, further including performing, using the beam positioning unit (9), a simultaneous and synchronous scanning movement for the predetermined number of partial beams (T) directed towards the workpiece (2) subsequent to the rough positioning and the positioning and/or moving steps.
36. The method according to claim 33, further including performing, using the optical control unit and/or the beam positioning unit, a positioning correction of positioning errors for the predetermined number of the partial beams (T) directed towards the workpiece (2) subsequent to the rough positioning step and, when necessary, subsequent to the positioning and/or moving step.
37. The method according to claim 36, further including determining a correction matrix using an optical measuring system, and performing the positioning correction step using the correction matrix.
38. The method according to claim 33, further including, subsequent to the rough positioning and the positioning and/or moving steps, performing (i) an individual scanning movement of at least some of the predetermined number of the partial beams using the optical control unit, and (ii) using the beam positioning unit (9), a simultaneous and synchronous scanning movement along a predetermined scanning track for the predetermined number of partial beams (T) directed towards the workpiece (2) and, when carrying out the individual scanning movement using the optical control unit, performing a dynamic positioning correction of positioning errors for the predetermined number of the partial beams (T) directed towards the workpiece (2).
39. (canceled)
Description
[0148] Other advantages, configurations and developments in connection with the laser processing device according to the invention or the method according to the invention are explained in more detail with reference to an exemplary embodiment described below. This is supposed to illustrate the invention to the person skilled in the art and make it possible for him to carry out the invention, without, however, limiting the invention. The features described with reference to the exemplary embodiment may also be used for developing the laser processing device according to the invention and the method according to the invention. The exemplary embodiment is explained in more detail with reference to the Figures. In the Figures:
[0149] FIG. 1 shows a schematic illustration of a workpiece surface, which can be processed with the laser processing device according to the invention or the method according to the invention, with a periodic arrangement of processing sites, wherein only a predetermined number of the processing sites is to be processed (e.g. flaws or bores), and a two-dimensional laser spot arrangement that can be imaged on the workpiece surface by means of a laser processing device according to the invention;
[0150] FIG. 2 shows a schematic view of a two-dimensional laser spot arrangement that can be imaged on the workpiece surface by means of the laser processing device according to the invention, wherein it is illustrated that, according to the invention, any number of laser spots can be imaged in any arrangement in space on the workpiece;
[0151] FIG. 3 shows a schematic view of a two-dimensional laser spot arrangement that can be imaged on the workpiece surface by means of the laser processing device according to the invention, wherein it is illustrated that, according to the invention, each partial beam or associated laser spot can be positioned within a partial beam scanning region at different positions, i.e. at the sites that are actually to be processed;
[0152] FIG. 4 shows a schematic view of a two-dimensional laser spot arrangement that can be imaged on the workpiece surface by means of the laser processing device according to the invention, wherein it is illustrated that the partial beams or associated laser spots are simultaneously and synchronously subjected to a joint scanning movement;
[0153] FIG. 5 shows a schematic view of a two-dimensional laser spot arrangement that can be imaged on the workpiece surface by means of the laser processing device according to the invention, wherein it is illustrated that the partial beams or associated laser spots are subjected to an individual scanning movement;
[0154] FIG. 6a shows the schematic structure of a laser processing device according to the invention;
[0155] FIG. 6b shows an example of a possible beam trajectory in a laser processing device according to FIG. 6a;
[0156] FIGS. 7, 8 show a schematic view regarding the functional principle of the optical control unit that is a part of the laser processing device, particularly of the microscanners;
[0157] FIG. 9 shows a schematic perspective view of a part of the laser processing device according to another embodiment of the invention;
[0158] FIG. 10 shows a schematic cross-sectional view of a part of the laser processing device according to another embodiment of the invention;
[0159] FIG. 11 shows a schematic cross-sectional view of a part of the laser processing device according to another embodiment of the invention.
[0160] The laser processing device proposed with the invention, or the associated method, are suitable for processing or repairing several processing sites 1 simultaneously in a workpiece 2 or associated surface. In particular, the present invention relates to the repair of displays or display components, e.g. OLED displays or mini LED displays. Particularly preferably, the present invention (laser processing device, method) is also suitable for carrying out drilling processes (e.g. in ceramic materials). On the one hand, static processing, but on the other hand also scanning processing can thus be carried out at the above-mentioned processing sites. The possibilities for an application of the invention mentioned here are not all-encompassing.
[0161] As was already described above, the laser processing device according to the invention, or the associated method, is suitable in particular for processing sites 1 of a workpiece 2, e.g. of flaws or bore positions. Before specifically discussing the details of the laser processing device according to the invention, the basic principle of the fundamental processing principle on which the invention is based will be explained in general terms with reference to the FIGS. 1 to 5.
[0162] FIG. 1 schematically shows a workpiece 2 to be processed with a (periodic) grid or pattern of a plurality of processing sites 1 that can be processed in principle. The processing sites 1 that can be processed in principle may constitute a periodic structure of pixels of the workpiece 2, for example. In the present case, a matrix of possible processing sites 1 is shown, of which certain processing sites 1 are intended to be processed (be it for repair, for example, or for carrying out a drilling process at the above-mentioned sites). In the present case, as an example, three of the processing sites 1 or pixels that can be processed in principle are labeled with a cross, which is supposed to represent that a corresponding laser processing is to be carried out at these sites. The processing sites 1 may include sub-structures (not shown). In the following, it may be assumed in one's mind that the labeled processing sites 1 have to be processed (e.g. repaired or drilled) by means of laser processing, e.g. because of local material inhomogeneities, layer thickness fluctuations or a desired bore, etc.
[0163] FIG. 1 further shows a configuration of laser spots 17, or a two-dimensional array of three-by-three laser spots 17, which are disposed within a master scanning region S.sub.M and imaged on the workpiece 2. The master scanning region S.sub.M defines a region which is in principle accessible for laser processing by projecting the partial beams T onto the workpiece surface, i.e. without additionally positioning the workpiece 2 relative to the laser processing device or vice versa. However, this does not preclude the possibility of the partial beams T or laser spots 17 located within the master scanning region S.sub.M being shifted together (i.e. the master scanning region S.sub.M) relative to the workpiece 2, or of the workpiece 2 being shifted relative to the master scanning region S.sub.M or the partial beams T (or laser spots 17) disposed therein. This may be done by using a beam positioning unit 9, for instance, with which the partial beams T located within the master scanning region S.sub.M can be synchronously and simultaneously shifted on the surface of the workpiece 2. It is also possible to image only a predetermined number of partial beams T on the workpiece 2 and move and/or position them synchronously and simultaneously on the surface of the workpiece 2 (this may also be carried out using a beam positioning unit 9). It may be emphasized that a relative displacement of laser spots 17 imaged on the workpiece 2 may also take place by moving or positioning the workpiece 2 relative to statically orientated (or moving) partial beams T.
[0164] According to the invention, the laser spots 17 result from a beam splitting of a laser beam L carried out with a beam splitting unit 5 in the laser processing device (in this respect, see FIG. 6). Selecting, by means of a corresponding partial beam selection, from the array of the laser spots 17 only those laser spots 17 that are necessary for processing the processing sites 1 provided and imaging them on the workpiece 2, i.e. three laser spots 17 in the example according to FIG. 2, is one of the core ideas of the invention. At the same time -as was already mentioned—it is also possible to carry out parallel processing on the processing sites 1 of a periodic processing pattern with the maximum number of partial beams T or the associated laser spots 17 (the maximum number is determined by the beam splitting unit 5).
[0165] In the example according to FIG. 1, however, the three-by-three laser spots 17 imaged on the workpiece 2 are not directed towards the processing sites to be processed (see the processing sites 1 labeled with a cross). As was already mentioned, however, the laser processing device is configured for directing also only a predetermined number of partial beams T (or associated laser spots 17) of a maximum possible number of partial beams T (or laser spots 17) towards the workpiece 2. In FIG. 2, only those partial beams T (or associated laser spots 17) are directed towards the workpiece 2 into whose partial beam scanning region S.sub.T the sites to be processed (labeled with a cross) fall. The partial beam scanning region S.sub.T is the region of a partial beam T in which the latter, or an associated laser spot 17, can be individually and flexibly positioned and/or scanned by means of an optical control unit associated with the laser processing device (independently of the other partial beams T). The scanning region 20 is schematically illustrated with an arrow in FIG. 1. Given a positioning of the laser spots 17 in accordance with FIG. 2, no processing of the processing sites 1 labeled with the cross would be possible. Accordingly, the laser spots 17 or the partial beams T can be individually positioned within the respective partial beam scanning regions S.sub.T (see FIG. 3), i.e. in the region of the sites that are actually to be processed.
[0166] After the laser spots 17 have been positioned, the processing of the sites to be processed can take place. However, it is also readily possible to subject the partial beams T or laser spots 17 to a processing movement. In a first variant - as is illustrated with the arrows in FIG. 4—this may proceed in a synchronous and simultaneous manner. As is shown in FIG. 4, also only a predetermined number of the partial beams T or associated laser spots 17 directed towards the workpiece 2 may in this case be subjected to the above-mentioned movement. Such a synchronous and simultaneous movement of partial beams T of laser spots 17 is preferably provided by a beam positioning unit 9. At the same time, the workpiece 2 may also be moved relative to static or moving partial beams T. Alternatively, it is also possible to subject the respective partial beams T directed towards the workpiece 2 to an individual processing movement (scanning movement) within the partial beam scanning region S.sub.T. In that case, the movement is not carried out synchronously but individually for each partial beam T. This is illustrated in FIG. 5, in which the different paths of movement of the scanning movement of the individual partial beams T or laser spots 17 are indicated with the arrows or arrow series therein, which point in different directions. As will be explained below, the individual scanning movement is carried out with the optical control unit.
[0167] Thus, an arbitrary configuration of laser spots 17 can be imaged on the workpiece 2 (adapted to a pattern of processing sites or flaws), limited in this case by the maximum number of partial beams T that can be generated by means of the beam splitting unit 5. A spot array (e.g. a 3×3 array) predefined by beam splitting is imaged on the workpiece 2 without a beam selection (FIG. 1).
[0168] Among other things, the method according to the invention or the laser processing device according to the invention is characterized in that such processing sites 1 can be simultaneously processed in a parallelized process, namely in an arbitrary spatial configuration. With respect to the example of repairing flaws, the method described with the present invention is more cost-effective and faster compared with repair techniques based on single-beam laser processing.
[0169] As is shown in FIGS. 1 to 4, the laser processing device proposed with the present invention is capable of projecting a plurality of partial beams T formed from a laser beam L onto the workpiece 2 to be processed; that is, an array or a bundle of partial beams T can be imaged on the workpiece 2. The number and arrangement in space of the partial beams T imaged on the workpiece 2 can be flexibly adjusted. Thus, the partial beams T are flexibly switchable; i.e., even only individual ones of the partial beams T associated with the array may readily be directed towards the workpiece 2 (FIG. 2). With the laser processing device according to the invention, it is thus possible to apply laser radiation (or the laser spots formed by the partial beams T) to the workpiece 2 selectively at certain processing sites 1, at which sites to be processed (see, for example, the processing sites 1 in FIGS. 2 and 3 labeled with a cross) are formed. In the case of flaw repair, excess material of the workpiece 2 present at these processing sites 1 can be ablated by means of laser processing, for example. Thus, processing sites 1 of the workpiece 2 can be processed both within a predetermined master scanning region S.sub.M (meaning a processing region spanned by the partial beams T projected onto the workpiece 2) and beyond this scanning region. The latter is possible particularly by a relative displacement of the workpiece 2 with respect to the positionally fixed laser processing device, alternatively also by displacing the master scanning region S.sub.M with respect to the workpiece surface (e.g. by means of a beam positioning unit 9), which is shown in FIG. 4, for example. A combination of a relative displacement of the workpiece 2 relative to the laser processing device and a scanning movement of the master scanning region S.sub.M including the partial beams T directed towards the workpiece 2, which is carried out by the laser processing device, particularly by a beam positioning unit 9, is also possible.
[0170] In contrast to the laser processing devices or methods known from the prior art, the laser processing device (and the method) proposed with the present invention is not limited to imaging individual lines or columns of an array of partial beams T on the workpiece 2, but rather, geometrically arbitrary combinations of spot arrangements can be provided on the workpiece 2. It is not necessary to commit to a certain spatial pattern or a number of the partial beams T; rather, any partial beams T of the bundle of partial beams T provided by the beam splitting unit 5 may be selected and transferred in the direction of the workpiece 2 by the optical control unit (the latter may also include a beam selecting unit 16).
[0171] Another core feature of the invention relates to the individual positionability of each partial beam T in a partial beam scanning region S.sub.T (FIGS. 3, 5), wherein the partial beam scanning region S.sub.T includes a smaller lateral extent than the above-mentioned master scanning region S.sub.M. Thus, the master scanning region S.sub.M includes a number of partial beam scanning regions S.sub.T corresponding to the number of partial beams T directed towards the workpiece 2. As will be explained in more detail below by describing the structure of the design of the laser processing device with reference to FIG. 5, each of the partial beams T directed towards the workpiece 2 can be individually positioned at different sites (FIG. 3) within a partial beam scanning region S.sub.T or moved within this region (FIG. 5) by means of an optical control unit. The individual positioning or movement of each partial beam T within the respective partial beam scanning region S.sub.T is carried out independently of the other partial beams T. Each of the partial beams T can be individually controlled by means of the optical control unit. Accordingly, the laser processing device proposed with the invention is not only suitable for processing periodically arranged processing patterns or processing sites 1, but also for processing non-periodically or partially periodically arranged processing sites 1. The capability for individually positioning laser spots 17 associated with the partial beams T is depicted in FIG. 3, wherein the laser spots 17 are not arranged centrally in the partial beam scanning region S.sub.T, but rather in the regions of the sites to be processed (processing sites 1 marked with a cross). FIG. 5 illustrates that the partial beams T directed towards the workpiece 2, or the associated laser spots 17, may also undergo an individual scanning movement, which is carried out within the respective partial beam scanning regions S.sub.T. In this case, the scanning movements of the individual partial beams T or laser spots 17 can traverse different movement paths (illustrated by the sequences of arrows).
[0172] The schematic structure of the laser processing device according to the invention is presented in FIG. 6a. The illustration therein is a schematic representation. Meanwhile, the specific beam trajectory is presented in detail in an exemplary example in FIG. 6b, namely for a beam splitting process of a laser beam L generated by a laser radiation source 3 into three partial beams T, which in turn comprise three sub-partial beams T.sub.S each. On the workpiece 2, the sub-partial beams T.sub.S (depicted for only one of the partial beams T) are focused on a laser spot, which is why, with respect to a partial beam T or a laser spot associated with the partial beam T, it must be taken into account in the present description that the beam trajectory relates to a number of sub-partial beams T.sub.S. FIG. 6b illustrates the detailed course of the partial beams T or sub-partial beams T.sub.S starting from a beam splitting unit 5 up to a beam positioning unit 9.
[0173] In order to process a workpiece 2 with a laser processing device according to the invention, the workpiece 2 is disposed in a workpiece holder, which is not depicted. The workpiece holder may be configured in the form of an xy-table that can be moved in a horizontal plane.
[0174] As shown in FIG. 6a, the laser processing device first of all comprises a laser radiation source 3, with which a laser beam L is generated and emitted along an optical path 4 in the direction of the workpiece 2, in particular in the form of laser pulses. A beam splitting unit 5 is disposed downstream of the laser radiation source 3 in the beam direction. The beam splitting unit 5 is configured for splitting the laser beam L into a plurality of partial beams T. The beam splitting unit 5 may be a diffractive optical element (DOE) known per se, or an SLM. The number of partial beams T can already be preset with the beam splitting unit 5. A rough adjustment of the distances between the laser spots of the partial beams T present in a plane of the workpiece 2 can also be already set with the beam splitting unit 5. A laser beam L can be divided with the beam splitting unit 5 into partial beams T that provide a two-dimensional spatial pattern of laser spots 17 on the workpiece 2. As can be seen in FIG. 6b, each partial beam T comprises a number (in this case three) of sub-partial beams T.sub.S, which in the present case may be referred to, as a combination, as partial beams T or main beams H.sub.S. Only the course of the main beams H.sub.S is shown in FIG. 6a.
[0175] Starting from the laser radiation source 3, a collimated laser beam L thus hits the beam splitting unit 5. The beam splitting unit 5 splits the laser beam into a bundle of identical partial beams T that each have a defined angle to one another.
[0176] A beam shaping element may be provided (not shown) between the laser radiation source 3 and the beam splitting unit 5, with which, in combination with the beam splitting unit 5, a plurality of partial beams T with a predetermined intensity distribution, e.g. a top-hat intensity distribution or ring-shaped intensity distribution, can be generated on the workpiece from a laser beam L with a Gaussian intensity distribution.
[0177] The laser processing device shown in FIGS. 6a and 6b includes an optical functional unit 7 disposed between the beam splitting unit 5 and a reflective optical functional unit 8. In this case, the optical functional unit 7 (which may be configured to be transmissive, but does not have to be) includes a group of optical functional elements 10, 12 disposed one behind the other. Thus, the (in this case transmissive) optical functional unit 7 comprises a focusing unit 10 (which may be formed of successively arranged lenses or lens systems, for example) and a lens array 11 of lenses 12 disposed at a distance from the focusing unit 10. In this case, the lens array 11 always comprises one more “line” or “column” of lenses 12 compared with the number of microscanners 15 in the array 14.
[0178] In the sense of the invention, a transmissive optical functional unit 7 is to be understood such that the components associated with the transmissive optical functional unit (the focusing unit 10 and the lens array 11) are penetrated by the partial beams T. In contrast, the partial beams T are reflected on the reflective optical functional unit 8.
[0179] On a first beam track up to being reflected on the reflective optical functional unit 8, the partial beams T associated with the bundle of partial beams T pass through the focusing unit 10 and the lens array 11 (see, for example, the propagation of the lower partial beam T.sub.H in FIG. 6a, or of the upper partial beam T including the sub-partial beams Ts in FIG. 6b). After the reflection T on the reflective optical functional unit 8, at least a portion of the partial beams T reflected thereon again passes through the optical functional unit 7 on a second beam track, particularly through the lens array 11 and the focusing unit 10. Subsequent to the beam splitting process in the beam splitting unit 5, the partial beams T accordingly propagate as a bundle of collimated partial beams T in the direction of the focusing unit 10. The partial beams T are collimated and focused by the focusing unit 10.
[0180] As can be seen from the course of the partial beam T.sub.H in FIG. 6a or of the partial beams T in FIG. 6b, for example, each partial beam T of the bundle of partial beams T, on the first beam track, passes through a lens 12 of the lens array 11 assigned to the respective partial beam T. The sub-partial beams T.sub.S of a respective partial beam T also pass through a common lens 12 (FIG. 6b). On the second beam track, at least a portion of the partial beams T reflected on the reflective optical functional unit 8 again pass through the lens 12 of the lens array 11 assigned to the respective partial beam T. Depending on the number of partial beams T to be imaged on the workpiece 2, a portion of the reflected partial beams T may be deflected by the reflective optical control unit 8 in the direction of a beam selecting unit 16, whereby the partial beam T is removed or absorbed from the beam path. Thus, it may be provided that not all of the partial beams T passing through the focusing unit 10 and the lens array 11 on the first beam track end up in the direction of the workpiece 2, but are previously (preferably on the second beam track) deflected or removed from the beam path by suitable means. A partial beam T can be removed or deflected from the beam path either by means of a beam selecting unit 16 provided specifically for this purpose (it may deflect a partial beam T from the beam path, e.g. in the direction of a beam dump), or a partial beam T is directed in the direction of a beam selecting unit 16 or of a beam dump by the reflective optical functional unit 8. In accordance with the number of partial beams T required for processing at a given position of the master scanning region S.sub.M on the workpiece 2, the corresponding number of non-required partial beams T can thus be deflected or removed from the beam path of the partial beams T.
[0181] As FIGS. 6a and 6b also make apparent, the focusing unit 10 is arranged in such a manner that a partial beam bundle axis A.sub.B, prior to the partial beams T hitting the focusing unit 10 on the first beam track, is offset relative to an axis of symmetry A.sub.F of the focusing unit 10 extending along the optical path 4. The offset of the bundle of partial beams T or of the partial beam bundle axis A.sub.B relative to the axis of symmetry A.sub.F of the focusing unit 10 causes the partial beam bundle axis A.sub.B to extend at an angle to the axis of symmetry A.sub.F of the focusing unit 10 subsequent to passing through the focusing unit 10, of which an impression is shown in FIG. 6b.
[0182] It can also be seen that the bundle of partial beams T, subsequent to passing through the focusing unit 10 on the first beam track, has a telecentric beam path. This can be seen particularly well in the detailed illustration of FIG. 6b. As is shown therein, the partial beams T (here, a bundle of three partial beams T is shown by way of example), is respectively composed of a bundle of a predetermined number of sub-partial beams T.sub.S (shown for the upper partial beam T). A telecentric beam path is understood to mean that the sub-partial beams T.sub.S can each be described by a main beam H.sub.S, wherein the main beams H.sub.S are parallel to one another after passing through the focusing unit 10. The main beams H.sub.S are composed of sub-partial beams T.sub.S.
[0183] The partial beams T of the bundle of partial beams T are focused on the first beam track in a plane E disposed perpendicular to the optical path 4 or to the axis of symmetry A.sub.F of the focusing unit 10, wherein the plane E is preferably disposed between the focusing unit 10 and the lens array 11. Also on the second beam track, it may be advantageous to focus the partial beams T of the bundle of partial beams T in the above-mentioned plane E after they have passed through the lens array 11.
[0184] The lens array 11 comprises a lateral (two-dimensional) assembly of lenses or lens systems 12, which are disposed in a common lens plane 19, wherein the lens plane 19 is disposed perpendicular to the optical path 4 or to the axis of symmetry A.sub.F of the focusing unit 10. In this case, the lenses 12 of the lens array 11 are arranged in such a way that each partial beam T (including the sub-partial beams T.sub.S) of the bundle of partial beams T passes through one lens 12 in each case. Such an assembly permits a separation of the partial beams into separate optical channels. Each partial beam T passing through the lens array 11 or the individual lenses 12 is collimated by the respective lens 12 of the lens array 11. The distance between the focusing unit 10 and the lens array 11 is selected such that the partial beams T are substantially collimated after passing through the lens array 11. After the partial beams T have passed through the lens array 11, the partial beams T propagate in the respective optical channels on the first beam track until they hit the reflective optical functional unit 8. On the whole, the distances and focal lengths of the optical components are selected in such a way that a beam splitting plane in the beam splitting unit is imaged onto the individual microscanners 15, and the microscanners 15 are equally imaged onto a common plane. This is done by combining the focusing unit 10 and the lens array 11. It is accomplished by the above-mentioned second imaging that the individual optical channels cross each other in a plane - even if an individually set partial beam direction is changed.
[0185] The optical functional unit 8 is formed from an array 14 of reflective microscanners 15. The array 14 of reflective microscanners 15 is preferably configured in a lateral two-dimensional assembly of reflective microscanners 15, wherein the microscanners 15 are disposed in a common microscanner plane 36. The microscanner plane 36 extends perpendicularly to the optical path 4 or to the axis of symmetry A.sub.F of the focusing unit 10. In this case, the reflective microscanners 15 are arranged in such a way that one partial beam T (or the associated sub-partial beams T.sub.S) is in each case reflected by one microscanner 15. The angle of incidence a of each partial beam T on the respective reflective microscanner 15 in this case approximately corresponds to the above-mentioned angle between the partial beam bundle axis A.sub.B and the axis of symmetry A.sub.F of the focusing unit 10. Accordingly, the number of the reflective microscanners 15 corresponds to the number of partial beams T extending along the first beam track. After a respective partial beam T has hit a reflective microscanner 15, the partial beam T is reflected on this microscanner 15.
[0186] As is illustrated, in particular, in FIGS. 7 and 8, an additional angle value x can be added (FIG. 8) with a respective microscanner 15 to a partial beam T incident on the microscanner, compared with a simple reflection according to the principle angle of incidence α=angle of reflection β (FIG. 7). This can be effected by tilting the microscanner 15 from a basic position. As is shown in FIG. 8, the microscanner 15 can in this case be tilted with its microscanner axis 36 relative to a microscanner plane 18. The additional addition of an angle in the end permits an additional offset of the laser spots 17 imaged on the workpiece 2 and a capability of the laser spots 17 to be positioned or moved within the respective partial beam scanning regions S.sub.T.
[0187] Thus, an angle of deflection of the partial beams T can be adjusted with the respective microscanners 15 in a flexible manner. In this case, the microscanners are adjusted preferably in a mechanical manner, wherein the deflection angles are adjusted by means of a control unit (not shown) connected to the array 14 of microscanners 15 or the individual microscanners 15.
[0188] After the partial beams T have passed through the lens array 11 on the second beam track, the above-mentioned addition of an angle results in a lateral offset of the respective focal point of the partial beams T in the plane E. Consequently, the angular deflection induced with the microscanners 15 has an effect on the position of the partial beams T directed towards the workpiece 2. In this case, the plane E (which may also be referred to as an intermediate focal plane) is imaged in the processing plane of an objective associated with the beam positioning unit 9.
[0189] The respective collimated partial beams T propagate along the second beam track back to the lens array 11 subsequent to being reflected at the microscanners 15. Depending on the angular deflection at the reflective array 14 of microscanners 15, the partial beams T now have an additional angular deflection compared with a partial beam T reflected on a microscanner 15 in the basic position (in accordance with FIG. 7). The bundle of collimated partial beams T again hits the lens array 11. In the process, a substantially collimated partial beam T passes through exactly one lens 12 of the lens array 11. Conversely, each lens 12 of the lens array 11 is penetrated by exactly one partial beam T of the bundle of partial beams reflected on the array 14 of microscanners 15. On the first beam track (i.e. the beam track from the focusing lens 10 to the lens array 11) and the second beam track (i.e. the beam track from the array 14 of microscanners 15 to the lens array 11), a partial beam T thus penetrates the lens array 11 twice with a different, in particular opposite, propagating direction.
[0190] As is illustrated in the FIGS. 6a and 6b, a partial beam T.sub.R (including sub-partial beams Ts, see FIG. 6b), on the second beam track, passes through a lens 12′ of the lens array 11, which is disposed adjacent to a lens 12 of the lens array 11 through which the partial beam Tx passes on the first beam track. Thus, the partial beams T on the first beam track (which may also be referred to as the forward journey of the partial beams T towards the reflective optical functional unit 8) pass through a different lens 12 of the lens array 11 than on the second beam track (which may also be referred to as the return journey of the partial beams T back from the reflective optical functional unit 8). The lenses 12, 12′ though which a single partial beam T passes on the first and the second beam track are preferably—but not necessarily—adjacently disposed. Only due to this fact is a separation (which is to be understood to be a separation into solid angle directions) of the channels on the forward and return journeys made possible by the array 14 of microscanners 15.
[0191] As was already mentioned and depicted in FIGS. 6a and 6b, the partial beams T again pass through the focusing unit 10 as a bundle of partial beams T on the second beam track, wherein the partial beam bundle axis A.sub.B, prior to the partial beams T hitting the focusing unit 10 on the second beam track, is offset relative to the axis of symmetry A.sub.F of the focusing unit extending along the optical path 4. At this point, it must be emphasized that the focusing unit 10 causes the partial beams T of the bundle of partial beams passing through the focusing unit 10 on the second beam track to converge; that is, the optical axes of the partial beams T run towards one another (in the case of the telecentric beam trajectory mentioned above, the partial beams even meet at a point in space). In the general case, however, the symmetry of the arrangement of the partial beams about the common partial beam bundle axis A.sub.B is broken, because each partial beam may have a different angle (because of the individual angle addition by the reflective optical functional unit 8). Preferably, the focusing unit 10 collimates every partial beam T passing through the focusing unit 10.
[0192] The laser processing device shown in the exemplary embodiment according to FIGS. 6a and 6b also includes a beam positioning unit 9, particularly in the form of a galvanometer scanner, which is configured for carrying out a rough positioning process, relative to the workpiece 2, of the partial beams T directed towards the workpiece 2, namely by positioning a master scanning region S.sub.M including the partial beam scanning regions S.sub.T relative to the workpiece 2. At the respective positions of the master scanning regions S.sub.M (and thus of the partial beams T) set by means of the rough positioning process, an individual fine positioning process of the partial beams T may be carried out within predetermined partial beam scanning regions S.sub.T of the respective partial beams T, subsequent to the rough positioning process. All of the partial beams T directed towards the workpiece 2 are thus delivered by means of the beam positioning unit 9.
[0193] With the beam positioning unit 9, the partial beams T directed towards the workpiece 2 can be moved, preferably synchronously and simultaneously, across the workpiece 2, namely by moving the master scanning region S.sub.M including the partial beam scanning regions S.sub.T relative to the workpiece 2.
[0194] The beam positioning unit 9 is downstream of the optical control unit 6 with respect to the beam direction or the beam path; thus, the beam path of the partial beams T is configured such that the partial beams T hit the beam positioning unit 9 only after being reflected at the reflective optical control unit 6. As was already mentioned several times, individual scanning programs or scanning movements can be executed also for the individual partial beams T or laser spots 17 imaged on the workpiece 2.
[0195] With respect to the second beam track, a focusing optics unit 13, with which the partial beams T (directed towards the workpiece 2) are focused on the workpiece 2 while forming laser spots 17, is disposed downstream of the beam positioning unit. For example, the focusing optics unit 13 may be configured as a lens, preferably as a F-theta lens, which is also referred to as a flat field lens.
[0196] FIG. 9 shows a schematic perspective view of a part of the inventive laser processing device according to another embodiment of the invention. What is shown is the beam trajectory or structure in the region between the lens array 11 and the reflective optical functional unit 8. Also shown is an assembly with a 2×2 assembly of microscanners 15.
[0197] As was already mentioned in the general part of the description, it is possible to deviate from arranging the micro scanners 15 in the form of an array 14 of microscanners 15 disposed in a microscanner plane 18 parallel to the lens array 11. This is done by carrying out an additional deflection of the partial beam bundles or partial beams T between the lens array 11 and the microscanners 15. The microscanners 15 may then be disposed at different positions in space.
[0198] As is shown in FIG. 9, a mirror device 42 is disposed between the lens array 11 and the microscanners 15, which is disposed and configured such that the partial beams T passing through the lens array 11 or the lenses 12 on the first beam track are respectively directed in the direction of one of the microscanners 15, and the partial beams T reflected at the microscanners 15 are each directed in the direction of the lens array 11 on the second beam track. With respect to the optical path 4, the partial beams T in the exemplary embodiment according to FIG. 9 are directed radially outward, for example, whereby the laser processing device can be given a more compact configuration (particularly in the direction of the optical path 4) and more construction space is available for arranging the microscanners.
[0199] The mirror device 42 shown in FIG. 9 has a plurality of mirror surfaces 43, wherein each mirror surface 43 is configured so as to deflect a partial beam T passing through the lens array 11 or a lens 12 of the same on the first beam track in the direction of one of the microscanners 15, and to deflect a partial beam T reflected at one of the microscanners 15 in the direction of the lens array 11 on the second beam track. In the example shown in FIG. 9, the mirror device 42 is a pyramid mirror. Such an arrangement makes it possible to dispose the microscanners 15 in different planes E1, E2, E3, E4 (indicated by chain-dotted lines), wherein the planes E1, E2, E3, E4 are each situated at an angle to the lens plane 19. Thus, construction space is saved and the laser processing device can be given a more compact configuration.
[0200] According to another variant (see FIG. 10), the deflection may take place in different planes along the beam propagation, so that the arrangement positions of the microscanners 15 (compared with the arrangement of the microscanners 15 in a common microscanner plane 18) can also be separated.
[0201] As is shown in FIG. 10, the mirror device 42 comprises for this purpose a plurality of mirrors 44, wherein a first number of the mirrors 44 is disposed in a first mirror plane S1 and a second number of the mirrors 44 in a second mirror plane S2, wherein the mirror planes S1, S2 are disposed preferably perpendicularly to the optical path 4 or to the axis of symmetry A.sub.F and spaced apart from each other. In the depicted example, the mirror planes S1, S2 are disposed parallel to the lens plane 19.
[0202] In this case, the mirrors 44 disposed in the mirror planes S1, S2 are disposed at an angle to the mirror planes S1, S2. Each mirror 44 is configured so as to direct a partial beam T passing through the lens array 11 on the first beam track in the direction of one of the microscanners 15, and to direct a partial beam T reflected at one of the microscanners 15 in the direction of the lens array 11 on the second beam track.
[0203] FIG. 11 shows another embodiment of the invention, in which galvanometer scanners are used as microscanners 15, instead of micromirrors or MEMS mirrors/MEMS scanners. The microscanners 15 configured in this manner have two mirror elements 45 with separate scanner axes. Each of the microscanners 15 is configured for deflecting in two coordinate directions a partial beam T hitting it. A perfect telecentricity cannot be achieved by separating the scanner axes to two mirror elements 45. However, even in the case of today's single-beam scanner systems, this small deviation does not constitute a great limitation.
[0204] As is shown in FIG. 11, a mirror device 42 in the form of several mirrors 44 is provided also in the case of such a configuration of the microscanners 15. The deflection of the partial beams T is depicted with dotted and continuous lines for two exemplary beam trajectories. The laser processing device can be given a compact configuration also in this exemplary embodiment, because the size of the lens array is largely uncoupled from the dimensions of the microscanners or the microscanner assembly.
LIST OF REFERENCE NUMERALS
[0205] 1 Processing site [0206] 2 Workpiece [0207] 3 Laser radiation source [0208] 4 Optical path [0209] 5 Beam splitting unit [0210] 7 Optical functional unit [0211] 8 Reflective optical functional unit [0212] 9 Beam positioning unit [0213] 10 Focusing unit [0214] 11 Lens array [0215] 12 Lens [0216] 13 Focusing optics unit, F-theta lens [0217] 14 Array [0218] 15 Microscanner [0219] 16 Beam selecting unit [0220] 17 Laser spot [0221] 18 Microscanner plane [0222] 19 Lens plane [0223] 20 Scanning region [0224] 36 Microscanner axis [0225] 40 Workpiece holder [0226] 42 Mirror device [0227] 43 Mirror surface [0228] 44 Mirror [0229] 45 Mirror element [0230] L Laser beam [0231] T Partial beam [0232] Tx Partial beam [0233] TR Partial beam [0234] Ts Sub-partial beam [0235] A.sub.B Partial beam bundle axis [0236] A.sub.F Axis of symmetry [0237] E Plane [0238] E1 Plane [0239] E2 Plane [0240] E3 Plane [0241] E4 Plane [0242] H.sub.S Main beam [0243] S.sub.T Partial beam scanning region [0244] S.sub.M Master scanning region [0245] S1 First mirror plane [0246] S2 Second mirror plane [0247] α Angle of incidence [0248] β Angle of reflection [0249] x Additional angle
