Laser processing apparatus with optical device comprising a beam splitter

Abstract

The present application relates to a laser processing apparatus having: an optical device; wherein the optical device has an input for receiving a laser beam; wherein the optical device has a beam splitter which splits the laser beam into at least two sub-beams; wherein the optical device recombines the sub-beams together to form a laser spot and produce an interference pattern in the laser spot; wherein a first state of the laser beam at the input generates a first interference pattern and a second state of the laser beam generates a second interference pattern; wherein the first state and the second state differ by at least one of (i) a position of the laser beam at the input end and (ii) an angle of incidence of the laser beam relative to the input end; and wherein the optical device is configured such that the second interference pattern follows the first interference pattern in phase.

Description

[0001] This application is a divisional application of a patent application with an application date of June 19, 2020, application number 2020800481895, and invention name “Laser processing equipment having an optical device including a beam splitter”. Technical Field

[0002] The subject matter disclosed herein relates to the field of laser processing equipment. Background Art

[0003] Processing surfaces and components by laser radiation has a wide range of applications, such as surface structuring. For example, WO 2018 / 197555 A1 discloses a method and an apparatus for producing riblets, wherein the riblets are introduced into a surface, in particular an already painted and cured surface, by laser interference structuring (DLIP-Direct Laser Interference Patterning). Components with ribs produced in this way enable aircraft, ships and wind turbines to operate with less flow resistance. Summary of the invention

[0004] In view of the foregoing, there is a need for an improved technique which enables structuring of surfaces having improved properties.

[0005] The subject matter of the independent claim takes this need into account. Advantageous embodiments are given in the dependent claims.

[0006] According to a first aspect of the herein disclosed subject matter, an apparatus, in particular a laser processing apparatus, is disclosed.

[0007] According to an embodiment of the first aspect, a laser processing device is disclosed, which includes: an optical device; the optical device has an input end for receiving a laser beam; and wherein the optical device has a beam splitter that divides the laser beam into at least two sub-beams; and wherein the optical device recombine the sub-beams to form a laser spot and generate an interference pattern in the laser spot; wherein a position change of the laser beam at the input end and / or a change in the incident angle of the laser beam relative to the input end results in at least one of the following: (i) a distance change DP of the distance between the center of the laser spot and the interference maximum value of the interference pattern closest in a predetermined direction, (ii) a position change DS of the center position of the laser spot; wherein the optical device is configured so that the following conditions apply to continuous position changes:

[0008] DS+DP=n*L Equation 1

[0009] And wherein n is a natural number; wherein L is the distance between two adjacent interference maxima of the interference pattern in a predetermined direction, including a tolerance range of ±5%; and wherein the distance variation DP is defined by the difference between the first distance and the second distance; and wherein each of the first distance and the second distance is defined in a predetermined direction.

[0010] According to a second aspect of the herein disclosed subject matter, a method is disclosed.

[0011] According to an embodiment of the second aspect, a method for interference structuring of a surface is disclosed, the method comprising: generating a first interference pattern on the surface; generating a second interference pattern on the surface; wherein the first interference pattern and the second interference pattern are generated by a single optical device having an input end; wherein the first interference pattern and the second interference pattern are generated by the optical device changing the position of the laser beam relative to the input end and / or the incident angle of the laser beam relative to the input end, thereby (i) a distance change DP of a distance between the center of the laser spot and the interference maximum value of the interference pattern closest in a predetermined direction, and / or (ii) a position change DS of the center position of the laser spot; wherein the optical device is configured so that the following conditions apply to continuous position changes:

[0012] DS+DP=n*L Equation 1

[0013] And wherein n is a natural number; L is the distance between two adjacent interference maxima of the first interference pattern, including a tolerance range of ±5%; and wherein the distance variation DP is defined by the difference between the first distance and the second distance; and wherein each of the first distance and the second distance is defined in a predetermined direction.

[0014] According to an embodiment of the third aspect, a use is disclosed.

[0015] According to an embodiment of the third aspect, it is disclosed to use an optical device to change the position of the laser beam at the input end and / or change the incident angle of the laser beam relative to the input end to generate a first interference pattern and a second interference pattern, thereby causing at least one of the following: (i) a distance change DP of the distance between the center of the laser spot and the interference maximum value of the interference pattern closest in a predetermined direction, (ii) a position change DS of the center position of the laser spot; wherein the optical device is configured so that the following conditions apply to the continuous change of the position:

[0016] DS+DP=n*L Equation 1

[0017] wherein n is a natural number; L is the distance between two adjacent interference maxima of the interference pattern, including a tolerance range of ±5%; and wherein the distance variation DP is defined by the difference between the first distance and the second distance; and wherein each of the first distance and the second distance is defined in a predetermined direction.

[0018] According to a fourth aspect of the herein disclosed subject matter, a laser processing apparatus is disclosed.

[0019] According to an embodiment of the fourth aspect, a laser processing device is disclosed, which includes: an optical device; the optical device has an input end for receiving a laser beam; and wherein the optical device has a beam splitter that divides the laser beam into at least two sub-beams; and wherein the optical device recombine the sub-beams together to form a laser spot and generate an interference pattern in the laser spot; wherein a first state of the laser beam at the input end generates a first interference pattern and a second state of the laser beam generates a second interference pattern; wherein the first state and the second state differ in at least one of the following: (i) the position of the laser beam at the input end and (ii) the incident angle of the laser beam relative to the input end; and wherein the optical device is configured so that the second interference pattern continues the first interference pattern in phase.

[0020] According to a fifth aspect of the herein disclosed subject matter, a method is disclosed.

[0021] According to an embodiment of the fifth aspect, a method is disclosed, the method comprising: providing an optical device having a beam splitter, the beam splitter splitting a laser beam into at least two sub-beams, wherein the optical device recombine the sub-beams to form a laser spot; aligning the laser beam onto an input end of the optical device; wherein a first state of the laser beam at the input end generates a laser spot at a first position P1, wherein the laser spot has a first interference pattern; wherein a second state of the laser beam at the input end generates a laser spot at a second position P2, wherein the laser spot has a second interference pattern; wherein the first state and the second state differ in at least one of (i) the position of the laser beam at the input end and (ii) the incident angle of the laser beam relative to the input end; and wherein for a position change DS=P1-P2, the optical device provides a difference DI_AB=DI_A-DI_B between a first optical path length difference DI_A and a second optical path length difference DI_B, which results in a distance change DP between the center of the laser spot and the interference maximum of the interference pattern closest in a predetermined direction, so that the second interference pattern continues the first interference pattern in phase.

[0022] According to a sixth aspect of the subject matter disclosed herein, a laser processing apparatus is disclosed.

[0023] According to an embodiment of the sixth aspect, a laser processing device is disclosed, which includes: an optical device; wherein the optical device has an input end for receiving a laser beam; wherein the optical device has a beam splitter that splits the laser beam into at least two sub-beams; wherein the optical device recombines the two sub-beams to form a laser spot and generates an interference pattern in the laser spot; wherein a first state of the laser beam at the input end generates a first interference pattern and a second state of the laser beam generates a second interference pattern, wherein the first state and the second state are distinguished by at least one of the following: (i) a position of the laser beam at the input end and (ii) an incident angle of the laser beam relative to the input end; wherein a center of the first interference pattern and a center of the second interference pattern have a distance corresponding to a diameter of at least a single laser spot, in particular at least five times the diameter of the laser spot, further in particular at least ten times the diameter of the laser spot, and further in particular at least twenty times the diameter of the laser spot; wherein due to the state change from the first state to the second state, the change in the path length of the radiation path of each sub-beam is less than ±5%, in particular less than ±1%, and further in particular less than ±0.5% of the total path length from the beam splitter to the laser spot.

[0024] According to a seventh aspect of the herein disclosed subject matter, an object is disclosed.

[0025] According to an embodiment of the seventh aspect, an object is disclosed, having a surface with a periodic surface structure, wherein the surface structure is defined by circular lines, and wherein the circular lines at least segmentally on the circular line segments have a periodically repeated shape of basic elements, and wherein the periodicity of the surface structure is different from the periodicity of the circular line segments.

[0026] According to an eighth aspect of the herein disclosed subject matter, an object is disclosed.

[0027] According to an embodiment of the eighth aspect, an object is disclosed, having a surface having a surface structure; wherein the surface structure has a maximum depth relative to the surface; the depth extension of the surface structure from a first position at the edge of the surface structure to a second position increases to 80% of the maximum depth extension; and the distance between the first position and the second position is at least 100 μm.

[0028] The basic concept underlying the various aspects and embodiments of the subject matter disclosed herein is that the interference pattern of the laser spot continues beyond the laser spot in phase. This can be accomplished, for example, by appropriate adjustment of the phase, for example, by providing a suitable difference DI_AB between the optical path difference of the first state and the optical path difference of the second state. In addition, the inventors have found that, contrary to the opinions of relevant experts, at least for a specific optical device, it is also feasible to cause the interference pattern to continue "automatically" in phase outside the spatial range of the laser spot simply by the construction of the optical device. In any case, in applications where large-area processing by periodic patterns is advantageous, laser processing equipment can be configured extremely effectively by phase true continuation.

[0029] According to an embodiment of the first aspect, the laser processing equipment is designed to provide the functions of one or more embodiments disclosed herein and / or to provide the functions required by one or more embodiments disclosed herein, in particular the embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0030] According to an embodiment of the second aspect, the method is designed to provide the functionality of one or more embodiments disclosed herein and / or to provide the functionality required by one or more embodiments disclosed herein, in particular embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0031] According to an embodiment of the third aspect, the use is designed to provide the functionality of one or more embodiments disclosed herein and / or to provide the functionality required by one or more embodiments disclosed herein, in particular embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0032] According to an embodiment of the fourth aspect, the laser processing equipment is designed to provide the functions of one or more embodiments disclosed herein and / or to provide the functions required by one or more embodiments disclosed herein, in particular the embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0033] According to an embodiment of the fifth aspect, the method is designed to provide the functionality of one or more embodiments disclosed herein and / or to provide the functionality required by one or more embodiments disclosed herein, in particular embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0034] According to an embodiment of the sixth aspect, the laser processing equipment is designed to provide the functions of one or more embodiments disclosed herein and / or to provide the functions required by one or more embodiments disclosed herein, in particular the embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0035] According to an embodiment of the seventh aspect, the object is designed to provide the functionality of one or more embodiments disclosed herein and / or to provide the functionality required by one or more embodiments disclosed herein, in particular embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0036] According to an embodiment of the eighth aspect, the object is designed to provide the functionality of one or more embodiments disclosed herein and / or to provide the functionality required by one or more embodiments disclosed herein, in particular embodiments of the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects.

[0037] Further advantages and features of the subject matter disclosed herein emerge from the following exemplary description of currently preferred embodiments, to which, however, the disclosure is not limited.The various figures in the drawings of the present application are to be regarded as schematic only and are not necessarily drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The functional principle of an optical device according to an embodiment of the herein disclosed subject matter is schematically illustrated.

[0039] Figure 2 A laser processing apparatus according to an embodiment of the herein disclosed subject matter is shown.

[0040] Figure 3 A part of a laser processing device according to an embodiment of the herein disclosed subject matter is shown.

[0041] Figure 4 A part of a laser processing device according to an embodiment of the herein disclosed subject matter is shown.

[0042] Figure 5 Shown are a first interference pattern and a second interference pattern, which may be produced by a laser processing apparatus according to embodiments of the herein disclosed subject matter.

[0043] Figure 6 A part of an optical arrangement of a laser machining device according to an embodiment of the herein disclosed subject matter is shown in a cross-sectional view.

[0044] Figure 7 A part of an object according to an embodiment of the herein disclosed subject matter is shown.

[0045] Figure 8 A part of an object according to an embodiment of the herein disclosed subject matter is shown.

[0046] Fig. 9 A part of an object according to an embodiment of the herein disclosed subject matter is shown.

[0047] Fig.10 Shows Fig. 9 Part of the surface structure along Fig. 9 Sectional view of section line XX in.

[0048] Fig.11 A plan view of a portion of a surface structure according to an embodiment of the herein disclosed subject matter is shown.

[0049] Fig.12 and Fig.13 Shows Fig.11 The surface structure along Fig.11 Cross-sectional view along section lines XII-XII and XIII-XIII.

[0050] Fig.14 A laser processing apparatus according to an embodiment of the herein disclosed subject matter is shown. DETAILED DESCRIPTION

[0051] Exemplary embodiments of the subject matter disclosed herein are described below, which for example relate to laser processing equipment, methods, uses and objects. It should be emphasized that any combination of features of different aspects, embodiments and examples is of course possible. In particular, some embodiments are described with reference to methods or uses, while other embodiments are described with reference to equipment, especially with reference to laser processing equipment or objects. However, a person skilled in the art will infer from the above and following descriptions, claims and drawings that, unless otherwise stated, the features of various aspects, embodiments and examples can be combined and the combination of these features should be considered to be disclosed by the present invention. For example, even features related to methods or uses can be combined with features related to equipment (such as laser processing equipment or objects), and vice versa. In addition, features of embodiments related to equipment can be combined with corresponding features related to methods or uses. With the disclosed method, embodiments of methods or functions, one or more actuators, and control devices with functions interacting with actuators should also be considered to be disclosed, and the control devices are designed to perform the methods or functions. In addition, with the disclosure of equipment functions, corresponding methods that define functions without equipment features are also considered to be disclosed. Furthermore, the features of the interference pattern define similar features of the surface structure or processing point (surface area processed by the laser spot with the interference pattern).

[0052] A method can be implemented as a computer-readable instruction code using any suitable programming language (e.g., JAVA, C#, etc.) and can be stored on a computer-readable medium (removable disk, volatile or non-volatile memory, embedded memory / processor, etc.). The instruction code can be used to program a computer or any other programmable processor device to perform the intended function. The instruction code can be obtained from a network, such as the World Wide Web, from which the instruction code can be downloaded.

[0053] The subject matter disclosed herein can be realized by program elements or software. However, the purpose of the present disclosure can also be realized using one or more specific electronic circuits or hardware. In addition, the subject matter of the present disclosure can also be realized in a hybrid form, that is, realized by a combination of software modules and hardware modules.

[0054] Unless otherwise indicated, numerical values ​​are to be understood as including a window of ±5%, i.e., for example, an indication of a length of 10 mm includes, according to one embodiment, a length in the interval (10 mm ±5%) = [9.95 mm; 10.05 mm], and according to one embodiment, a percentage of 50% includes a percentage in the interval 50% ±5% = [47.5%; 52.5%]. According to another embodiment, numerical values ​​are to be understood as including a window of ±10%.

[0055] According to one embodiment, a device is disclosed. According to another embodiment, the device is a laser processing device. According to another embodiment, the device has an optical device having an input end for receiving a laser beam. According to another embodiment, the optical device has a beam splitter that splits the laser beam into two or more sub-beams, wherein the optical device recombine the sub-beams together to form a laser spot so as to produce an interference pattern in the laser spot. According to another embodiment, wherein a change in the position of the laser beam at the input end and / or a change in the incident angle of the laser beam relative to the input end results in at least one of the following: (i) a distance change DP of the distance between the center of the laser spot and the interference maximum value of the interference pattern closest in a predetermined direction, (ii) a position change DS of the center position of the laser spot. According to another embodiment, the optical device is configured so that the following conditions apply to the continuous position change DS:

[0056] DS+DP=n*L Equation 1

[0057] And wherein n is a natural number. L is here the distance between two adjacent interference maxima of the interference pattern in a predetermined direction, including a tolerance range of ±5%. In other words, according to one embodiment, this condition does not have to be fully satisfied, but a deviation of the order of ±5% from the exact value n*L is also acceptable, i.e., the deviation within the tolerance range also satisfies the condition. Typically, according to another embodiment, the tolerance range is ±3%, or according to yet another embodiment, ±1%. According to yet another embodiment, equation 1 (tolerance range 0%) is fully satisfied. In addition, the distance variation DP is defined by the difference between the first distance and the second distance, wherein each of the first distance and the second distance is defined in a predetermined direction. The first distance and the second distance respectively give the distance between the center of the laser spot in question and the interference maximum value of the nearest interference pattern in the predetermined direction. || is a well-known absolute value function, i.e., for x≥0, |x|=x, and for x<0, |x|=-x.

[0058] Accordingly, according to one embodiment, a method includes one or more of the following embodiments. According to one embodiment, a method for surface interference structuring includes one or more of the following features: generating a first interference pattern on a surface; generating a second interference pattern on a surface; wherein the first interference pattern and the second interference pattern are generated by a single optical device having an input end. According to one embodiment, the first interference pattern and the second interference pattern are generated by an optical device changing the position of the laser beam at the input end and / or the incident angle of the laser beam relative to the input end, thereby (i) achieving a distance change DP between the center of the laser spot and the interference maximum value of the nearest interference pattern in a predetermined direction, and / or (ii) achieving a position change DS of the center position of the laser spot.

[0059] According to another embodiment, the method includes one or more of the following features: providing an optical device having a beam splitter that separates a laser beam into at least two sub-beams, wherein the optical device recombines the laser sub-beams together to form a laser spot; aligning the laser beam onto an input end of the optical device; wherein a first state of the laser beam at the input end produces a laser spot at a first position P1, the laser spot having a first interference pattern; wherein a second state of the laser beam at the input end produces a laser spot at a second position P2, the laser spot having a second interference pattern; wherein the first state and the second state differ in at least one of (i) the position of the laser beam at the input end and (ii) the incident angle of the laser beam relative to the input end; and wherein the optical device (or the method according to another embodiment) provides a difference DI_AB=DI_A-DI_B between a first optical path length difference DI_A and a second optical path length difference DI_B for a position change DS=P1-P2, which provides a distance change DP between the center of the laser spot and the interference maximum of the interference pattern closest in a predetermined direction, so that the second interference pattern continues the first interference pattern in phase.

[0060] According to one embodiment, the optical arrangement is configured such that the condition according to equation 1 applies for the continuous position variation D.

[0061] The position of the laser beam at the input and / or the change of the angle of incidence of the laser beam relative to the input can also be described more generally as the state of the laser beam at the input. According to one embodiment, the input of the optical device is formed by a beam splitter. Of course, this does not exclude the fact that an optical element is arranged in front of the beam splitter, however, in this sense, the optical element does not belong to the optical device.

[0062] In this sense, according to one embodiment, a first state of the laser beam at the input generates a first interference pattern in the laser spot (in the first laser spot, the center of the first laser spot is located at a first position P1) and a second state of the laser beam at the input end generates a second interference pattern in the laser spot (in the second laser spot, the center of the second laser spot is at a second position P2), wherein the difference between the first state and the second state lies in at least one of (I) the position of the laser beam at the input end and (I) the incident angle of the laser beam relative to the input end.

[0063] In accordance with the foregoing statements, according to one embodiment, a use includes using an optical device for generating a first interference pattern and a second interference pattern by changing the position of a laser beam at an input end and / or changing the incident angle of the laser beam relative to the input end and thereby causing at least one of the following: (i) a distance change DP of the distance between the center of the laser spot and the interference maximum of the interference pattern nearest in a predetermined direction, (ii) a position change DS of the center position of the laser spot, wherein the optical device is configured such that the condition according to equation 1 is satisfied.

[0064] According to another embodiment, the laser processing equipment has one or more of the following features: an optical device; wherein the optical device has an input end for receiving a laser beam; and wherein the device has a beam splitter that divides the laser beam into at least two sub-beams; and wherein the optical device recombine the sub-beams together to form a laser spot and produce an interference pattern in the laser spot; wherein a first state of the laser beam at the input end produces a first interference pattern, and a second state of the laser beam at the input end produces a second interference pattern; and wherein the first state and the second state differ in at least one of the following aspects: (i) the position of the laser beam at the input end and (ii) the incident angle of the laser beam relative to the input end; and wherein the optical device is configured so that the second interference pattern continues the first interference pattern in phase.

[0065] A change in the state of the laser beam at the input, and in particular a change in the position of the laser beam at the input and / or a change in the angle of incidence of the laser beam relative to the input, does not exclude that the optical device and the surface can be moved relative to each other in order to structure the surface over a larger area. For example, in the case of 2-beam interference (which results in an interference pattern with a large number of parallel lines), the optical device can be moved in the direction of the longitudinal extension of the lines in order to achieve a large-area surface structuring, which is desirable, for example, in applications where the surface structure generated by the interference pattern forms so-called ribs on a fluid element, such as an aircraft component.

[0066] According to one embodiment, the optical arrangement is configured such that the second interference pattern continues the first interference pattern in phase.

[0067] According to one embodiment, the corresponding configuration of the optical device can be active, for example, by adjusting the distance change DP, for example by suitable actuator means, which act, for example, on a mirror device or an optical medium. For example, a wedge-shaped optical element can be used for this purpose, which further moves a beamlet in or out, whereby the path length of the beamlet within the wedge-shaped optical element can be increased or decreased and the phase (and DP) can be changed. The control signal of the actuator means can be generated, for example, by determining the state of the laser beam by a look-up table or, for example, also by a suitably trained artificial intelligence.

[0068] Furthermore, according to one embodiment, the configuration of the optical device for the phase continuation of the first interference pattern may have a passive configuration, for example, if the individual elements of the optical device and the interactions of the individual optical elements are configured such that, at least within a certain effective range, such as an effective range of the laser beam state (e.g. within a specific effective range of the position of the laser beam at the input end and / or the incident angle of the laser beam relative to the input end) or an effective range of the position change DS, the phase of the first interference pattern is truly continued only based on the (static) structure of the optical device. In general, according to one embodiment, equation 1 is satisfied at least within an effective range.

[0069] According to one embodiment, a first state of the laser beam at the input end defines a first interference pattern and a first position P1 of the center of the laser spot, and a second state of the laser beam at the input end defines a second interference pattern and a second position P2 of the center of the laser spot, wherein a pair of sub-beams including at least two sub-beams in the first state have a first optical path length difference DI_A and a pair of sub-beams in the second state have a second optical path length difference DI_B; and wherein for a corresponding position change DS=P1-P2, the optical device provides a difference DI_AB=DI_A-DI_B between the first optical path length difference DI_A and the second optical path length difference DI_B, which results in a distance change DP, so that the second interference pattern continues the first interference pattern in phase.

[0070] According to one embodiment, the predetermined direction defining both the first distance and the second distance is a direction away from the center of the laser spot and toward the nearest interference maximum in that direction (e.g., the first interference pattern, i.e., according to one embodiment, the first interference pattern defines the predetermined direction. As long as the interference pattern has, for example, a plurality of parallel interference lines (such as generated by interference of two light beams), according to one embodiment, the predetermined direction is a direction perpendicular to the interference lines. For example, in this case, the predetermined direction can be defined as a direction perpendicular to the interference lines and pointing to the right from the center of the laser spot.

[0071] As known to those skilled in the art, in the case of interference of three or more sub-beams, for example in the case of three sub-beams (three-beam interference), the interference pattern is for example a dot pattern. According to one embodiment, there are two predetermined directions which are linearly independent of each other, along which the interference pattern can be continuous in phase, which is particularly advantageous in the case of three-beam interference.

[0072] It goes without saying that, although only various distances, such as the first distance and the second distance, are referred to in some embodiments, the relevant embodiments are applicable to all distances as long as the specified conditions in Equation 1 are satisfied.

[0073] According to one embodiment, the condition specified in equation 1 is valid within a predetermined valid range, such as a valid range defined by the optical device. According to one embodiment, the condition in equation 1 applies at least to a position change value equal to the laser spot diameter. According to another embodiment, the condition in equation 1 applies to a continuous position change DS from a starting position (position change equal to zero) until the position change value. According to another embodiment, the position change value is equal to twice the laser spot diameter, or according to other embodiments, equal to five times, ten times or twenty times the laser spot diameter. According to one embodiment, the input end has a first area and a second area, and the laser processing device has an actuator device for positioning the laser beam in the first area and then in the second area.

[0074] For example, according to one embodiment, the actuator device is an actuator device of a laser scanner, by which the laser beam can be scanned over the input end, in particular the first area and the second area of ​​the input end. In this way, a continuous and phase-true continuation of the interference pattern of the laser spot is possible.

[0075] In the sense of the above-described embodiments, for example, the first state may correspond to a laser beam incident on a first area, and the second state may correspond to a laser beam incident on a second area.

[0076] According to one embodiment, the first interference pattern and the second interference pattern overlap. For example, according to one embodiment, the first interference pattern and the second interference pattern have a plurality of intensity maxima and intensity minima, which are arranged in sequence in the longitudinal direction. According to one embodiment, the second interference pattern is offset longitudinally (or parallel to the longitudinal direction) relative to the first interference pattern. In addition, according to one embodiment, the longitudinal direction corresponds to the predetermined direction.

[0077] If there are at least two linearly independent longitudinal directions (eg, in the case of 3-beam interference according to one embodiment), the predetermined direction defining the first distance and the second distance is parallel to at least one of the longitudinal directions.

[0078] According to one embodiment, the optical device has at least one optical element that works in transmission mode (in other words, the at least one optical element is a transmission optical element). According to one embodiment, the path length section of the radiation path of each sub-beam in the transmission optical element (i.e. from each sub-beam whose radiation path passes through the transmission optical element) varies by less than ±5%, in particular less than ±1%, further in particular less than ±0.5%, wherein the variation of the path length section causes a variation of the state of the laser beam at the input end. According to one embodiment (i.e. optionally but not necessarily), all of the at least two sub-beams (generated by the beam splitter via the laser beam) pass through the transmission optical element.

[0079] According to one embodiment, the above-described embodiments regarding the transmitting optical element apply to each transmitting optical element of the optical device.

[0080] According to one embodiment, each illuminated surface pair of each transmission optical element of the optical arrangement after the beam splitter, which is located in the radiation path of at least one sub-beam, encloses an angle of at most 10 degrees, in particular at most 5 degrees. It has been found in experiments that smaller angles can promote phase continuation of the interference pattern.

[0081] According to one embodiment, the optical device defines a radiation path for at least one of the at least two sub-beams to which the following conditions apply: for a first position of the laser spot, the radiation path defines a first path difference between an optical path length of the radiation path and a geometric path length of the radiation path; for a second position of the laser spot, the radiation path defines a second path difference between an optical path length of the radiation path and a geometric path length of the radiation path. And within the effective range of the condition, at least one of the following applies: (i) the deviation between the first path difference and the second path difference is small enough to satisfy the condition; (ii) the deviation between the first path difference and the second path difference is less than twenty times, in particular less than ten times, of the wavelength of the laser beam; (iii) both the first path difference and the second path difference are less than 10 mm, in particular less than 5 mm.

[0082] According to one embodiment, the optics after the beam splitter are free of prisms.

[0083] Without wishing to be bound by theory, it is the current understanding of the inventors that, when changing the state of the laser beam or changing the position of the laser spot, a large deviation in the path length difference between the optical path length of the radiation path and the geometric path length of the radiation path is detrimental to the effective range or even hinders the phase continuation of the interference pattern of the laser spot.

[0084] According to one embodiment, the deviation between the first path length difference and the second path length difference is sufficiently small in the above sense in the sense that the deviation is less than 10% of the wavelength of the laser beam or the deviation causes the interference pattern to shift from the ideal phase by less than 5% of the distance L between two adjacent interference maxima in a predetermined direction.

[0085] According to one embodiment, all optical elements of the optical device work in a reflective manner; in particular, according to one embodiment, all optical elements of the optical device work only in a reflective manner. In other words, according to another embodiment, all optical elements of the optical device, except the beam splitter, are reflective elements.

[0086] According to one embodiment, the term "operating in a reflective manner" in the present application means that the optical element in question has an optical function based on reflection of incident electromagnetic radiation and contributes to the overall function of the optical device through this optical function. In this sense, a semi-transparent mirror also operates in a reflective manner.

[0087] According to one embodiment, the beam splitter is a semi-transparent mirror. According to one embodiment, the semi-transparent mirror is an optical transmission medium with flat surfaces, wherein at least one layer, in particular a dielectric layer stack, is applied to one of the flat surfaces (on the input side) so that a specific part of the incident laser intensity is (intentionally) reflected and another part is (intentionally) transmitted. The part of the incident laser intensity that is reflected is also referred to herein as reflected laser radiation. The part of the incident laser intensity that is transmitted is also referred to herein as transmitted laser radiation. The incident laser intensity is also referred to herein as laser beam intensity. On the exit side of the optical transmission medium, optionally, according to one embodiment, a dielectric layer stack with an anti-reflective effect is also applied so that the intensity that has entered the medium can leave again with low losses. According to one embodiment, the transmitted and reflected radiation have similar (or even identical) beam shapes and / or similar (or even identical) beam profiles. Furthermore, according to one embodiment, the transmitted radiation and the reflected radiation have the same polarization. This has the advantage that the polarization does not have to be adjusted again in one of the beams later. According to one embodiment, in order to obtain good interference, the two sub-beams require the same polarization.

[0088] According to one embodiment, the semi-transparent mirror is configured such that a significant part (greater than 10%) of the incident laser intensity is reflected and a significant part (greater than 10%) of the incident laser intensity is transmitted. Advantageously, the optical transmission medium of the laser beam has low absorption.

[0089] According to one embodiment, the beam splitter is configured such that the intensity of the reflected laser radiation is of the same magnitude as the intensity of the transmitted laser radiation. This type of beam splitter is referred to as a 50:50 beam splitter. According to another embodiment, the beam splitter is a non-polarizing 50:50 beam splitter.

[0090] According to one embodiment, the radiation plate is configured and arranged so that the laser beam generates a first intensity distribution in at least two sub-beams when incident on a first area (of the input end), and generates a second intensity distribution in the at least two sub-beams when incident on a second area (of the input end). According to one embodiment, the first intensity distribution and the second intensity distribution differ from each other by less than 10%. In other words, according to one embodiment, the intensity distribution in the at least two sub-beams is independent of the state of the laser beam within a tolerance range of 10%.

[0091] According to one embodiment, an object is processed by the laser processing apparatus described herein or the method described herein to realize an object having a surface structure according to the embodiments disclosed herein.

[0092] According to one embodiment, an object has a surface with a periodic surface structure, wherein the surface structure defines a circumferential line as an envelope of the surface structure, and wherein the circumferential line has a periodically repeating shape of basic elements at least segmentally in the circumferential line segments, and wherein the periodicity of the surface structure is different from the periodicity of the circumferential line segments.

[0093] In particular, the edge region of the surface structure may reflect the cross-sectional shape of the laser spot (or the cross-sectional shape of the processing spot generated thereby).

[0094] According to one embodiment, the surface structure has at least one of the following features: (i) the surface structure has a plurality of parallel grooves; (ii) the basic element has at least one arc segment (for example, a single or two or more arc segments); (iii) the circular line segment is a first circular line segment, the basic element is a first basic element, and the circular line has a second circular line segment that is opposite to the first circular line segment and is a periodic repetition of the second basic element, and wherein the periodicity of the surface structure is different from the periodicity of the second circular line segment.

[0095] According to another embodiment, the object has a surface with a surface structure having a maximum depth extension relative to the surface; the depth extension of the surface structure from a first position at the edge of the surface structure to a second position increases to 80% of the maximum depth extension; the distance between the first position and the second position is at least 100 μm. In other words, the depth extension of the surface structure from a first position at the edge of the surface structure to a second position increases to at most 80% of the maximum depth extension, wherein the distance between the first position and the second position is 100 μm.

[0096] A slow increase in the depth extension of the surface structure starting from the edge of the surface structure (80% of the maximum depth extension is reached only after 100 μm or more) may be advantageous in terms of flow, in particular if the surface structure is a rib structure, in particular a rib structure as described herein. According to an embodiment, the slow increase in the depth extension takes place in at least one direction, for example parallel to the flow direction in which the surface structure is to flow, as described herein.

[0097] Detailed description

[0098] Exemplary embodiments of the subject matter disclosed herein are described below with reference to the accompanying drawings. It should be noted that in different figures, similar or identical elements or components partially have the same reference numerals, or have reference numerals that differ only in the first position. Features or components that are identical or at least functionally identical to corresponding features or components in another figure are described in detail only when they appear for the first time, and the corresponding reference numerals are not repeated. According to one embodiment, the preceding definitions apply to the following embodiments, and vice versa. In addition, the features and embodiments described above can be combined with the features and embodiments described below.

[0099] Figure 1 The functional principle of an optical device 100 according to an embodiment of the herein disclosed subject matter is schematically illustrated.

[0100] According to one embodiment, the optical device 100 has an input 101 for receiving a laser beam 102. According to one embodiment, the optical device 100 is configured to split the laser beam 102 into at least two (e.g., two) sub-beams 104, 204, and recombining the sub-beams 104, 204 together to form a laser spot 106 to generate an interference pattern therein. According to one embodiment, the radiation paths of the sub-beams have the same length or almost the same length, such as the same length within a tolerance window of ±5%. In practical structures with limited beam diameters, especially the angles between the sub-beams lead to interference.

[0101] According to one embodiment, the first beamlet 104 of the two beamlets has a first optical path length I1 and the second beamlet 204 of the beamlets has a second optical path length I2. This results in a path length difference DI=I2-I1 of the beamlets. As described herein, a change in this path length difference DI results in a distance change DP. According to one embodiment, the laser spot 106 is directed onto the surface 107.

[0102] Figure 2 A laser processing apparatus 108 is shown according to an embodiment of the subject matter disclosed herein.

[0103] According to one embodiment, the laser processing device 108 has an optical device 200. According to one embodiment, the optical device 200 has a beam splitter 110, which splits the laser beam 102 into two sub-beams 104, 204. According to one embodiment, the beam splitter 110 is a semi-transparent mirror, such as Figure 2 According to one embodiment, the input end 101 of the optical device 200 is formed by a beam splitter 110. According to another embodiment, the optical device 200 defines a radiation path 112, 212 for each of the sub-beams 104, 204. According to one embodiment, the at least two radiation paths include a first radiation path 112 and a second radiation path 212. According to another embodiment, at least one radiation path has (e.g. each radiation path 112, 212) at least one optical element, such as at least one mirror 114, 214. According to one embodiment, as in Figure 2 As shown in FIG. 1 , three mirrors 114, 214 may be provided. According to one embodiment, at least one mirror 114, 214 defines the route of the associated radiation path 112, 212 through the optical device 200. According to one embodiment, the optical device 200 is configured (e.g. by arranging and / or aligning at least one optical element) to recombine the sub-beams 112, 212 together to form the laser spot 106. According to one embodiment, the sub-beams are brought together by suitable optical elements, such as mirrors 214, such as Figure 2 shown.

[0104] According to one embodiment, the optical device 200 is positioned relative to the surface 107 of the object so that the laser spot 106 and the interference pattern are generated on the surface 107 so as to process the surface 107 with the interference pattern. For example, the surface 107 is structured with the interference pattern, which is also called direct interference structuring.

[0105] According to one embodiment, the laser processing device has a laser source 116 for generating the laser beam 102. According to another embodiment, the laser source 116 is arranged outside the laser processing device and can be coupled thereto.

[0106] According to one embodiment, the laser beam is a CO2 laser beam, in particular a CO2 laser beam having a power of at least 800W (800 Watts). Thus, according to one embodiment, the laser source is a CO2 laser source. According to one embodiment, the CO2 laser source is configured to operate in continuous wave or with a pulse duration of <1ms (less than 1 millisecond).

[0107] According to a further embodiment, the laser processing device is configured to structure a paint surface, in particular a cured paint surface.

[0108] According to another embodiment, the laser processing device has at least one movable mirror 314 and an actuator device 118 for controlling the at least one movable mirror 314. According to one embodiment, the at least one movable mirror 314 is arranged to change the state of the laser beam at the input end 101, for example, to change the position of the laser beam at the input end 101 and / or the incident angle of the laser beam 102 relative to the input end 101. For example, by rotating the at least one movable mirror 314, the position and the incident angle of the laser beam 102 relative to the input end can be changed, for example Figure 2 A first state of the laser beam at the input end (solid line at 102) and a second state of the laser beam at the input end (dashed line at 102) are shown. Here, the laser beam 102 is positioned in a first region 119 of the semi-transparent mirror 110 (which is considered as the input end of the optical device according to one embodiment) in the first state and in a second region 121 of the semi-transparent mirror 110 in the second state.

[0109] According to one embodiment, the optical device 200 is configured such that the first state produces a first interference pattern and the second state produces a second interference pattern, wherein the second interference pattern continues the first interference pattern in phase. According to one embodiment, this phase continuation of the (first) interference pattern occurs even if the state of the laser beam at the input end 101 changes continuously, thereby effectively enabling an interference pattern of increasing size while achieving a defined phase relationship of interference maximum and interference minimum while obtaining the interference pattern of increasing size. Compared to scattering a single laser spot, the phase-continuous interference pattern achieves more uniform processing, because a single laser spot typically has a Gaussian beam profile. According to one embodiment, uniform processing of the surface is achieved by a uniformly integrated total intensity per unit area, and the intensity maxima generated are in phase (phase real).

[0110] The resulting interference pattern can be generated, for example, by deflecting the laser beam 102 at the input 101 , that is to say, according to one embodiment, by deflecting the laser beam 102 at the beam splitter 110 .

[0111] According to one embodiment, an optical element 128, in particular an optical element for focusing the laser beam, is provided, for example as part of an optical device or as part of a laser processing apparatus. According to one embodiment, the optical element for focusing the laser beam is a lens, for example a lens arranged between the at least one movable mirror 314 and the beam splitter 110, for example Figure 2According to another embodiment, the optical element 128 is a focus shifter. According to another embodiment, an optical element 228 is arranged between the laser source and the at least one movable mirror 314 (e.g. as a replacement or in addition to the optical element 128), in particular an optical element for focusing the laser beam, for example, as indicated by two dashed lines.

[0112] According to another embodiment, the laser processing device 108 has a control device 120 for controlling components of the laser processing device (e.g. the actuator device 118 and, if present, the laser source 116) by means of control signals 122. According to one embodiment, the control device comprises a processor device 124 and a storage device 126 for storing a computer program executable on the processor device 124 for thereby implementing the functions of an embodiment of the subject matter disclosed herein.

[0113] According to a further embodiment, a further actuator device 130 is provided for positioning the optical device 200 and the surface 107 relative to each other. This may be advantageous, for example, in the case of large-area laser processing, where, for example, the generated interference pattern moves on the surface 107. According to one embodiment, the further actuator device 130 may be controlled by the control device 120 of the laser processing device via the control signal 122, or alternatively by an external control device ( Figure 2 107). It should be understood that the (further) actuator device 130 is shown in the figures only as an example, in particular with regard to the position. For example, it can be provided that the optical device and, if necessary, other components of the laser processing device, such as the at least one movable mirror 314, the actuator device 118, the optical element 128 or the optical element 228, can be moved relative to the laser source 116 and the surface 107. For example, the optical device 100 (and optionally the optical element 228) can be mounted on a robot arm for positioning (and, if necessary, moving) these components above the surface 107. In this case, the robot arm forms the actuator device 130 or a part of the actuator device 130.

[0114] Figure 3 FIG. 2 shows a portion of a laser processing device 208 according to an embodiment of the subject matter disclosed herein. The laser processing device 208 may have a reference Figure 2 One or more features of the laser processing apparatus 108 described herein, even if the relevant features are not described in Figure 3 Shown in.

[0115] According to one embodiment, the laser processing device 208 has an optical device 300. Figure 2Unlike the optical device 200 described above, the optical device 300 has two mirrors 114, 214 in each radiation path 112, 212. Furthermore, according to one embodiment, an optical element 228 for focusing the laser beam 102 in a beam direction is arranged in front of at least one movable mirror 314. Furthermore, according to one embodiment, between at least one movable mirror 314 and the beam splitter 110 (which can be implemented as a semi-transparent mirror, for example, Figure 3 No optical elements are arranged between the two surfaces.

[0116] Figure 4 A portion of a laser processing apparatus 308 is shown according to an embodiment of the subject matter disclosed herein.

[0117] The laser processing equipment 308 may have the Figure 2 One or more features of the laser processing apparatus 108 described herein, even if the relevant features are not described in Figure 4 Shown in.

[0118] According to one embodiment, the laser processing device 308 has an optical arrangement 400. According to one embodiment, the beam splitter 110 of the optical arrangement is formed by a diffractive optical element (DOE), which splits the laser beam 102 into at least two sub-beams 104, 204.

[0119] According to one embodiment, the diffractive optical element is configured such that at least two sub-beams 104, 204 emitted therefrom enclose an acute angle, for example Figure 4 as shown in .

[0120] According to one embodiment, each of the radiation paths 112 , 212 of the at least two sub-beams 104 , 204 has a single optical element, for example a single mirror 214 .

[0121] refer to Figure 3 and Figure 4 The described optical arrangement 300 , 400 requires relatively few optical elements in the radiation path 112 , 212 , however a disadvantage is that the angle of incidence on the last mirror 214 is very flat, which may lead to distortions of the associated sub-beams 104 , 204 .

[0122] Figure 5 Shown are a first interference pattern 108 and a second interference pattern 208 produced by a laser processing apparatus according to an embodiment of the herein disclosed subject matter.

[0123] According to one embodiment, the first interference pattern 108 is formed by the laser spot 106, whose center 132 is located at the first position 134, and the second interference pattern 208 is formed by the laser spot 106, whose center 132 is located at the second position 136. The expression "the center 132 of the laser spot 106 is located at a specific position (e.g., the first position 134)" is also abbreviated herein as the expression "the laser spot 106 is located at a specific position". Therefore, these two formulas are considered to be equivalent. According to one embodiment, the laser spot 106 is generated at the first position 134 and the second position 136, wherein the first state of the laser beam at the input end of the optical device is adjusted for the first position 134 (according to one embodiment, with respect to the position and the incident angle of the laser beam), and the second state of the laser beam at the input end of the optical device is adjusted for the second position 136 of the laser spot 106.

[0124] The change in state of the laser beam (eg, change in angle of incidence and position) thus results in a position change 142 (also referred to herein as DS) in the position of the center 132 of the laser spot 106 .

[0125] According to one embodiment, the optical arrangement of the generated laser spot 106 is configured such that the second interference pattern 208 continues the first interference pattern 108 in phase, for example Figure 5 In the case of two-beam interference, for example, a constant distance 138 (also referred to here as L) between two adjacent interference maxima "also extends beyond the boundaries of the individual beams", indicating a phase continuation of the interference pattern.

[0126] Therefore, the phase position of the interference maximum 140 of the second interference pattern 208 coincides with the phase position of the interference maximum 140 of the first interference pattern 108. In other words, the first distance 141 between the center 132 of the laser spot 106 and the interference maximum 240 immediately adjacent in the predetermined direction 144 at the first position 134 and the second distance 241 between the center 132 of the laser spot 106 and the interference maximum 240 immediately adjacent in the predetermined direction 144 at the second position 136 are changed by the optical arrangement. In this case, the difference between the first distance 141 and the second distance 241 corresponds to the distance change DP.

[0127] According to one embodiment, the optical arrangement ensures phase continuity of the first interference pattern for a continuous position change (at least within an effective region, e.g., an effective range of position change). Thus, when the position of the center 132 of the laser spot 106 is continuously changed from the first position 134 to the second position 136, a continuous overlap (kontinuierliches) is generated in the region between the first interference pattern 108 and the second interference pattern 208. ). While ensuring the phase accuracy of each position, there is also an interference maximum 340 between the first position and the second position (such as Figure 5 ), which has the same phase relationship with the interference maximum 140 of the first interference pattern 108 and the interference maximum 140 of the second interference pattern 208. In other words, all interference maxima 140, 240, 340 generated by the continuous position change between the first position 134 and the second position 136 are in phase, for example Figure 5 shown.

[0128] Figure 6 A portion of an optical device 100 of a laser processing apparatus according to an embodiment of the herein disclosed subject matter is shown in cross-section.

[0129] According to one embodiment, the optical device 100 has at least one transmission optical element 150, which is located, for example, Figure 1 In the radiation path 112 of at least one of the sub-beams 104 of the sub-beams. According to one embodiment, the transmission optical element 150 has a pair of transmission surfaces, which include a first surface 154 and a second surface 156. According to another embodiment, the pair of surfaces 154, 156 form an angle 158, which according to one embodiment is at most 10 degrees.

[0130] Figure 7 A portion of an object 160 is shown according to an embodiment of the herein disclosed subject matter.

[0131] According to one embodiment, the object has a surface 107 having a periodic surface structure 162. According to one embodiment, the surface structure 162 has a plurality of parallel grooves extending in a periodic manner. Figure 7 In the figure, it is shown by a plurality of parallel lines 164. It should be noted that the line 164 is not intended to represent the size of the grooves of the surface structure 162, but is only intended to illustrate the periodicity. In fact, according to one embodiment, for example in a rib application, the grooves are wider than the ribs retained between the grooves. In this sense, according to one embodiment, the line 164 can represent, for example, the center line (or center line) of the groove. According to one embodiment, the surface structure is a groove structure having a plurality of grooves, as described in WO 2018 / 197555A1, i.e., a surface structure that reduces the surface flow resistance compared to a smooth surface. In particular, with regard to the application, function, shape, size, characteristics, etc. of the ribs, explicit reference is made to WO 2018 / 197555 A1, the entire contents of which are hereby incorporated herein by reference.

[0132] As is generally the case with ribs, in one embodiment, each groove has side walls. Thus, the adjacent walls of two adjacent grooves form two mutually facing flanks of the rib between the two grooves. In other words, according to one embodiment, a plurality of grooves produce a plurality of ribs in the surface, which, when of suitable size, act as ribs (i.e. reduce the flow resistance on the surface), such as described in WO 2018 / 197555A1 as described above. According to one embodiment, the sides of the ribs enclose an acute angle. In particular, according to one embodiment, the rib tapers to a point.

[0133] According to one embodiment, the ribs extend substantially parallel to each other and in particular parallel to the flow direction of an expected flow over the surface.

[0134] According to one embodiment, the periodic surface structure 162 is generated by exposure to a laser spot, which Figure 7 The first position in the surface 107 is shown by the dashed line at 106. According to one embodiment, the surface structure 162 is generated by generating the laser spot 106 at different positions on the surface 107. According to one embodiment, the laser spot has an interference pattern at each position, which continues the interference pattern of the laser spot at the first position in phase, for example Figure 7 According to one embodiment, the surface 107 is processed by each interference pattern, wherein each interference pattern generates a processing spot 169 in the surface 107. According to one embodiment, the surface structure 162 is generated by the sequential arrangement of the interference patterns or processing spots 169. If the laser source is a pulsed laser source, then in the optical device ( Figure 7 When the laser beam is continuously moved at the input end of the optical device (not shown), discrete processing spots 169 are obtained, which overlap and can be distinguished from each other when, for example, the pulse frequency of the laser or the movement speed of the laser beam at the input end of the optical device is appropriately selected, for example Figure 7 shown.

[0135] According to one embodiment, the processing spot 169 can be generated along a straight line, for example, along a direction 167 above the surface 107, such as Figure 7 shown.

[0136] The overlapping processing spots 169 thus define a circumferential line 168 which is the envelope of the surface structure and which, according to one embodiment, is located at least in one circumferential line section, e.g. Figure 7 The circular line segment 170 shown in FIG. 1 has a periodically repeated shape of basic elements, some of which are composed of Figure 7 According to one embodiment, the basic element is arc-shaped at least in sections, for example, in the shape of a circular arc. Figure 7According to another embodiment, the basic element can be a segment of an ellipse or a basic element of a different shape. According to one embodiment, for example, if the surface structure 162 is subjected to a fluid, the arc-shaped basic element or the arc-shaped portion of the basic element can cause the fluid to enter the surface structure not along a straight line and thus in a very narrow input end area, but through an input end area extending in the flow direction. This is advantageous in terms of fluid technology.

[0137] According to one embodiment, the periodicity of the surface structure 162 is different from the periodicity of the circumferential line segments 170, for example Figure 7 According to one embodiment, the difference in the periodicity of the surface structure 162 and the circumferential line segments 170 is due to the fact that the periodicity of the surface structure 162 is defined by the interference of at least two beamlets, while the circumferential line segments 170 are defined by the size of the laser spot and the overlap of the resulting processing spot 169 .

[0138] Figure 8 A portion of another object 260 is shown according to an embodiment of the herein disclosed subject matter.

[0139] According to one embodiment, the surface 107 of the object 260 has a periodic surface structure 162, which is generated by moving the laser spot 106 in two linearly independent directions. For example, the laser processing device can be configured to move the laser spot 106 along a tortuous path 172, such as Figure 8 shown.

[0140] The movement of the laser spot 106 in two linearly independent directions can be achieved, for example, by positioning the laser spot along a first path section 174 parallel to the first direction 167 and positioning the laser spot along a second path section 176 inclined (for example, perpendicular) to the first path section 174. In addition, it can be provided that the movement of the laser spot 106 in two linearly independent directions has two parallel path sections, for example Figure 8 According to one embodiment, the movement is performed in opposite directions in the two parallel path sections. Figure 8 182, whereby, for example, a tortuous path can be realized, for example Figure 8 According to one embodiment, the movement of the laser spot in the parallel path segments is always performed in the same direction (in Figure 8 For the overlap of the laser spots on the parallel path segments, it is necessary (along the second path segment, Figure 8The laser beam is turned off during the return movement according to one embodiment, so that no laser spot is generated during the reverse movement. In addition, according to one embodiment, it can be provided that the laser beam is turned off along the second path section 176, so that no laser spot is generated along the second path section. For example, it can be provided that the laser beam is turned on only at the end point of the path section, for example at the end point of the second path section 176, and thus a laser spot is generated in the end point, for example, as Figure 8 as shown in .

[0141] According to one embodiment, the positioning of the laser spot along parallel path segments, such as parallel path segments 174, 178, is produced by moving the laser beam at the input of the optical device, while the movement of the laser spot oblique to the parallel path segments, such as along path segments 176, 180, is performed by moving the surface 107 relative to the reference point 180. This has the advantage that larger surfaces can be processed. The movement of the surface 107 relative to the optical device can be performed continuously, wherein according to one embodiment, in order to achieve a predetermined path (e.g. Figure 8 ), the laser processing device is configured to achieve the correct movement by movement of the optical device relative to the reference point 184 and thereby position the laser spot along the predetermined path. According to one embodiment, the surface 107 is no longer moved relative to the reference point 184, but the laser processing device is configured to generate a movement oblique to the parallel path segment (for example, perpendicular to the path segment) by moving the laser beam at the input end of the optical device. In summary, the actuator device 118 and the at least one movable mirror 314 can be configured, for example, to achieve movement of the laser beam 102 in two mutually linearly independent directions. According to one embodiment, the actuator device 118 and the at least one movable mirror 314 can be formed by a galvanometer scanner known per se.

[0142] According to one embodiment, the surface structure 162 defines a first circumferential line segment 170 that is an introduction to the circumferential line, wherein the circumferential line segment 170 has a periodically repeated shape of a basic element 171. According to another embodiment, the surface structure 162 has a second circumferential line segment 172 that has a periodically repeated shape of a basic element 171, wherein the second circumferential line segment 172 is opposite to the first circumferential line segment 170, e.g. Figure 8 According to one embodiment, the second circumferential line segment 172 is a mirror image of the first circumferential line segment 170, for example Figure 8 as shown in .

[0143] Of course, under certain conditions, the circular line segment does not have a (recognizable) periodically repeated shape of the basic element, for example, when the laser beam is continuously (not pulsed) output during the positioning of the laser spot 106 along the first path segment 174, or when the overlap of the interference patterns of the individual pulses is very high. However, in this case, for example, when the continuous laser beam is turned off when positioning the other circular line segment 185, 186 in the direction 188, the other circular line segment 185, 186 can completely have a periodically repeated shape of the basic element.

[0144] Fig. 9 A portion of an object 360 is shown according to an embodiment of the subject matter disclosed herein.

[0145] Similar to Figure 8 , Fig. 9 Also shown is an object 360 having a surface 107 with a periodic surface structure 162, which surface structure defines a circumferential line that is an envelope of the surface structure 162. According to one embodiment, the circumferential line 168 has a first circumferential line segment 170 and a second circumferential line segment 172, which are periodic repetitions of a basic element 171, wherein according to one embodiment, the basic element 171 consists of a single arc portion, such as Fig. 9 According to another embodiment, the third circumferential line segment 185 of the circumferential line 168 is a periodic repetition of a basic element 183, wherein the basic element 183 is composed of two arc segments, for example, as shown in Fig. 9 According to another embodiment, the circumferential line 168 has a fourth circumferential line segment 186, which is a periodic repetition of another basic element 187, wherein the other basic element 187 is composed of two arc-shaped parts, such as Fig. 9 shown.

[0146] Fig.10 Shows Fig. 9 A portion of the surface structure 162 along Fig. 9 Sectional view of section line XX in.

[0147] According to one embodiment, surface 107 is formed by a paint layer 109 formed on a body of object 360 (the body is not covered in the Fig.10 According to one embodiment, the paint layer 109 is a cured paint layer, such as a paint layer of an aircraft. According to one embodiment, the surface structure 162 has Fig.10 According to one embodiment, the surface structure and thus at least one groove 189 has a maximum depth (or depth) 190, which according to one embodiment is less than a thickness 191 of the paint layer 109.

[0148] According to another embodiment, the depth extension of the surface structure 162 increases to 80% of the maximum depth extension from a first position 198 at the edge of the surface structure 162 to the closest second position 199. In this sense, "closest" means that if there are multiple second positions (where the depth extension reaches 80% of the maximum depth extension), those second positions are selected that have the smallest distance to the first position 198. According to another embodiment, the distance 163 between the first position 198 and the second position 199 is at least 100 μm, for example at least 300 μm or at least 500 μm.

[0149] For example, according to one embodiment, the depth 190 decreases in an edge region 192 of the trench 189 and continuously approaches zero, ie, approaches the level of the surface 107, such as Fig.10 According to one embodiment, the design of the surface structure 162 in its edge region 192 is due to the puncturing behavior of the laser, because the intensity of the laser spot in the edge region is usually lower than the intensity in the center of the laser spot (the average value of the interference pattern of the laser spot), so the erosion of the laser spot in the edge region 192 is lower. For example, the puncturing behavior with the characteristics described herein can be achieved by forming a layer of paint on the surface and processing it with a CO2 laser.

[0150] According to one embodiment, the painted surface is a painted surface as described in WO 2018 / 197555 A1. In particular, the painted surface is formed by a polymer-based paint, in particular based on polyurethane or acrylic or epoxy resin. According to one embodiment, the paint is a varnish or a topcoat. According to one embodiment, the absorption spectrum of the paint overlaps with the emission spectrum of the CO 2 laser. According to one embodiment, the CO 2 laser can be operated at a wavelength in the range between 9 μm and 11 μm.

[0151] According to one embodiment, the paint contains a pigment that affects the color of the paint. Typically, topcoats contain such pigments. According to another embodiment, the pigment changes the absorption behavior of the paint to the laser beam. According to one embodiment, the piercing behavior of the laser can be influenced by the type and concentration of the pigment.

[0152] According to one embodiment, the paint is a first layer of paint arranged on a second layer of paint. The first layer of paint is therefore also referred to as a topcoat layer and the second layer of paint is therefore also referred to as a primer layer. According to one embodiment, the topcoat layer is a clearcoat layer or a topcoat layer, in particular based on polyurethane. According to another embodiment, the primer layer is made by an epoxy system (e.g. cured epoxy resin) or generally by plastic.

[0153] Fig.11 A plan view of a portion of a surface structure 162 is shown according to an embodiment of the herein disclosed subject matter.

[0154] As mentioned above, the surface structure 162 defines an envelope, also referred to herein as a circumference 168. Similar to the diagrams already explained above, in Fig.11 The surface structure 162 is only schematically shown by a plurality of parallel lines, wherein each line represents a groove 189 ( Fig.11 not shown).

[0155] Fig.12 and Fig.13 Shows Fig.11 The surface structure 162 along Fig.11 In addition, the arrow 193 indicates that the corresponding section lines are assigned to Fig.12 and Fig.13 .

[0156] According to one embodiment, the parallel grooves 189 have a shallower depth in the edge region 192 (at Fig.11 ), for example, Fig.11 Summary and Fig.13 and Fig.12 It can be seen.

[0157] The depth added from one edge of the surface structure can also be Fig.12 and Fig.13 It should be understood that if at 80% of the maximum depth extension, the surface structure has no depression, the second position 199 corresponding to 80% of the maximum depth extension can also be determined by interpolation or extrapolation. According to one embodiment, it can be provided, for example, that starting from the first position, the second position is determined in the direction of the maximum gradient of the depth extension along the surface structure.

[0158] Fig.14 A laser processing apparatus 408 is shown according to an embodiment of the subject matter disclosed herein.

[0159] According to one embodiment, the laser processing apparatus 408 has an optical device 500 formed according to one or more embodiments disclosed herein.

[0160] According to another embodiment, the laser processing device 408 has a scanning device 194, which can have, for example, an actuator device according to an embodiment of the object disclosed herein and at least one movable mirror. According to one embodiment, the scanning device 194 is constituted by a galvanometer scanner. According to one embodiment, the scanning device 194 is configured to direct the laser beam 102 onto the input end 101 of the optical device 500 or to move the laser beam 102 on the input end 101 of the optical device 500.

[0161] According to another embodiment, the laser processing device 408 has a laser input 195 that can be coupled to the laser source 116. According to one embodiment, the laser input 195 is formed by a scanning device 194, such as Fig.14 According to one embodiment, the laser source 116 is external to the laser processing device 408. For example, if the laser processing device 408 is mounted on a robotic arm, the laser source 116 can be positioned next to the robotic arm on the floor and optically coupled to the laser input end 195. According to another embodiment ( Fig.14 ), the laser source 116 is part of the laser processing equipment 408.

[0162] According to one embodiment, the optical arrangement causes the laser beam 102 to generate at least two sub-beams 112 , 212 , which generate an interference pattern in the laser spot 106 .

[0163] According to one embodiment, object 160 is positioned relative to optical device 500 such that laser spot 106 is located on surface 107 of object 160 .

[0164] According to one embodiment, a further actuator device 130 is assigned to the laser processing device, by which the optical device 500 and the object 160 can be moved relative to each other, for example in order to structure surface parts of the object 160 that cannot be covered merely by moving the laser beam 102 at the input end 101 of the optical device 500.

[0165] According to one embodiment, the further actuator device 130 has at least one first actuator 196, with which the object 160 can be moved relative to the reference point 184. According to one embodiment, the further actuator device 130 also has at least one second actuator 197, with which the laser processing device 408 is movable relative to the reference point 184. According to one embodiment, the at least one second actuator 197 is formed by a robot arm.

[0166] It should be noted that the entities disclosed herein (e.g., devices, features, method steps, control devices, actuator devices, optical devices, actuators, optical elements, etc.) are not limited to dedicated entities as described in some embodiments. Instead, the subject matter disclosed herein can be implemented in a variety of ways while still providing the specific functions disclosed.

[0167] In particular, the subject matter described in the present invention may be provided in different ways at the device level, at the method level, or at the software level while still providing the specified functionality. It should also be noted that, depending on the embodiment, a separate entity may be provided for each function disclosed in the present invention. According to other embodiments, an entity may be configured to provide two or more functions as described in the present invention. For example, according to one embodiment, Figure 2The functionality of the two reflectors 214 in the embodiment may be implemented by a single top cover edge reflector. According to other embodiments, two or more entities may be configured to together provide the functionality as described in the present invention.

[0168] It should be noted that the embodiments of the present invention described in the accompanying drawings represent only a limited selection of possible embodiment variants of the subject matter disclosed in the present invention. The features of the various embodiments can be combined with each other in a suitable manner, so that a person skilled in the art can consider that a plurality of different embodiments have embodiment variants described herein. It should also be mentioned that terms such as "one" or "a kind of" do not exclude pluralities. Terms such as "including" or "having" do not exclude further features or process steps. The terms "having" or "including" or "comprising" all include the two meanings of "having" and "consisting of...".

[0169] It should also be noted that although the example objects and elements (e.g., laser processing equipment, optical components, etc.) in the drawings show specific combinations of several embodiments of the objects disclosed in the present invention, any other combinations of the embodiments are also possible and considered to be disclosed by the present application.

[0170] Advantageous combinations of embodiments of the subject matter disclosed herein can be summarized as follows:

[0171] A laser processing device comprises: an optical device; wherein the optical device has an input end for receiving a laser beam; wherein the optical device has a beam splitter that splits the laser beam into at least two sub-beams; wherein the optical device recombine the sub-beams to form a laser spot and generate an interference pattern in the laser spot; wherein a first state of the laser beam at the input end generates a first interference pattern and a second state of the laser beam generates a second interference pattern; wherein the first state and the second state are distinguished by at least one of the following: (i) a position of the laser beam at the input end and (ii) an incident angle of the laser beam relative to the input end; and wherein the optical device is configured so that the second interference pattern continues the first interference pattern in phase.

Claims

1. An object (160, 260, 360) having a surface (107), the object having a periodic surface structure (162), wherein the surface structure (162) defines a circumferential line (168) as an envelope of the surface structure (162), and wherein the circumferential line (168) has a periodically repeating shape of basic elements (171, 183, 187) at least in sections in circumferential line segments (170, 172, 185, 186), and wherein the periodicity of the surface structure (162) is different from the periodicity of the circumferential line segments (170, 172, 185, 186), wherein the circumferential line (168) is defined by overlapping processing light spots (169), and the processing light spots (169) include a first processing light spot and a second processing light spot; wherein the surface structure (162) has a plurality of parallel grooves (189); wherein the surface structure (162) includes a first portion in the first processing light spot and a second portion in the second processing light spot, and the second portion of the surface structure (162) continues the first portion of the surface structure (162) in phase; A first distance between a center of the first processing spot and a groove closest to the predetermined direction is different from a second distance between a center of the second processing spot and a groove closest to the predetermined direction.

2. The object (160, 260, 360) according to claim 1, wherein the surface structure (162) has at least one of the following features: The basic element has at least one arc-shaped segment; The circumferential line segment is a first circumferential line segment (170, 185), the basic element is a first basic element (171, 183), and The circumferential line (168) has a second circumferential line segment (172, 186) opposite the first circumferential line segment (170, 185).

3. The object (160, 260, 360) according to claim 1 or 2, wherein the surface (107) is a painted surface.

4. The object (160, 260, 360) according to claim 3, wherein the surface (107) is formed by a paint layer (109), the paint layer (109) being formed on a body of the object (160, 260, 360).

5. The object (160, 260, 360) according to claim 4, wherein the maximum depth (190) of the surface structure is smaller than the thickness of the paint layer (109).

6. The object (160, 260, 360) according to claim 3, wherein the painted surface is formed by a polymer-based paint.

7. The object (160, 260, 360) according to claim 6, wherein the lacquer is based on polyurethane or acrylic or epoxy resin.

8. The object (160, 260, 360) according to claim 6, wherein the paint is a clear paint or a top paint.

9. The object (160, 260, 360) according to claim 1 or 2, wherein the depth of the parallel grooves (189) decreases in the edge region (192).

10. An object (160, 260, 360) according to any one of claims 1 or 2, wherein the circumferential line segments (185, 186) have a periodically repeated shape of the basic elements (171, 183, 187) because the continuous laser beam is turned off when the circumferential line segments (185, 186) are positioned in the direction (188).

11. The object (160, 260, 360) according to any one of claims 1 or 2, wherein the surface structure extends from the surface of the object to the depth of the object.

12. An object (160, 260, 360) having a surface, wherein The surface (107) has a surface structure (162); The surface structure (162) has a maximum depth extension (190) relative to the surface (107); The depth extension of the surface structure (162) increases from a first position (198) to a second position (199) at an edge of the surface structure (162) to 80% of the maximum depth extension (190); and The distance (163) between the first position (198) and the second position (199) is at least 100 μm.

13. The object (160, 260, 360) according to claim 12, wherein the surface structure comprises a plurality of parallel grooves.

14. The object (160, 260, 360) according to claim 12 or 13, wherein the adjacent walls of each two adjacent grooves form two mutually facing flanks of the rib between the two adjacent grooves.

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