EP3941679A1

EP3941679A1 - Device and method for producing a multiplicity of grooves

Info

Publication number: EP3941679A1
Application number: EP20713262.2A
Authority: EP
Inventors: Tobias Dyck
Original assignee: 4JET Microtech GmbH
Current assignee: 4JET Microtech GmbH
Priority date: 2019-03-22
Filing date: 2020-03-19
Publication date: 2022-01-26
Also published as: AU2020246943A1; KR20210142141A; WO2020193366A1; BR112021017371A2; CN113573841A; US20220152741A1; CA3134472A1; DE202019101652U1; JP2022524953A

Abstract

A laser machining device (100) for producing a multiplicity of grooves in a surface (110) has an optical diffraction arrangement (102), which is designed for receiving laser radiation (104) and for then producing output radiation (106), wherein the output radiation (106) has a multiplicity of intensity maxima. An actuator arrangement (108) is provided for producing a relative movement between the output radiation (106) and the surface (110), wherein each intensity maximum produces a groove of the multiplicity of furrows.

Description

Apparatus and method for creating a plurality of furrows

TECHNICAL AREA

The subjects disclosed herein relate to the field of laser machining of surfaces.

BACKGROUND

WO 2018/197555 Al discloses a method and a device for

Production of riblets, with the riblets being introduced into a surface, in particular into an already painted and cured surface, by means of laser interference structuring (DLIP - Direct Laser Interference Patterning). A component with the riblets produced in this way makes it possible to operate aircraft, ships and wind turbines with less flow resistance.

SUMMARY

In view of the situation described above, there is a need for a technique which allows laser machining of surfaces with improved characteristics.

This need is taken into account by the subjects of the independent claims. Advantageous embodiments are specified in the dependent claims.

MW: bm According to the first aspect of the subject matter disclosed herein, an apparatus is disclosed, in particular a laser processing apparatus for producing a plurality of furrows in a surface.

According to embodiments of the first aspect,

A laser processing device for generating a plurality of furrows in a surface discloses, the laser processing device comprising: an optical diffraction arrangement which is set up to receive a laser radiation and to generate an output radiation thereon, the output radiation having a plurality of intensity maxima; and an actuator arrangement for generating a relative movement between the output radiation and the surface, each intensity maximum (the plurality of intensity maxima) generating one of the plurality of furrows.

According to a second aspect of the subjects disclosed herein, a method is disclosed, in particular a method for creating a plurality of furrows in a surface.

According to embodiments of the second aspect, a method for creating a plurality of furrows in a surface is disclosed which

A method comprising: directing a laser beam onto an optical one

Diffraction arrangement for generating an output radiation, the output radiation having a plurality of intensity maxima; Directing the output radiation onto the surface; and creating relative motion between the output radiation and the surface, each

Intensity maxima (the plurality of intensity maxima) generates one of the plurality of furrows.

Various aspects and embodiments of those disclosed herein

Objects are based on the idea that laser machining Surfaces with improved characteristics can be provided by a plurality of intensity maxima from a laser beam (or the laser radiation) is generated directly through an optical diffraction arrangement (for example a diffractive optical element or a plurality of phase plates) and each intensity maximum of the plurality of

Intensity maxima is used to generate a furrow of the plurality of furrows.

According to embodiments of the first aspect, the

Laser processing device designed to provide the functionality of one or more of the embodiments disclosed herein and / or to provide the functionality as it is required for one or more of the embodiments disclosed herein, in particular the embodiments of the first or second aspect.

According to embodiments of the second aspect, the method is

configured to provide the functionality of one or more of the embodiments disclosed herein and / or to provide the functionality as it is for one or more of the embodiments disclosed herein

is required, in particular the embodiments of the first or second aspect.

Further advantages and features of the subject matter disclosed herein emerge from the following exemplary description of currently preferred embodiments, to which the present disclosure is not limited. The individual figures of the drawings of this application are only to be viewed as schematic and not necessarily true to scale. Rather, relative dimensions and angles may not be drawn to scale in order to clarify some embodiments of the subject matter disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows schematically a laser processing device according to

Embodiments of the subjects disclosed herein.

FIG. 2 shows the surface of the object from FIG. 1 viewed from the line II-II in FIG. 1.

Fig. 3 shows part of the plurality of furrows in Fig. 2 in one

Cross-sectional view along the line III-III in FIG. 2.

4 shows a laser processing device according to embodiments of the subjects disclosed herein.

FIG. 5 shows a plan view of a diffraction arrangement according to FIG

Embodiments of the subjects disclosed herein.

FIG. 6 shows the optical element of the diffraction arrangement from FIG. 5 in a cross-sectional view.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following are exemplary embodiments of the herein

disclosed objects described, for example on a

Laser processing device or a method is referred to. It should be emphasized that any combination of features from various aspects, embodiments and examples is of course possible.

In particular, some embodiments are described with reference to a method, while other embodiments are described with reference to a Laser machining device will be described. However, those skilled in the art from the preceding and following description, claims and drawings will appreciate that, unless otherwise indicated, features of various aspects, embodiments and examples

can be combined and such combinations of features are to be regarded as disclosed by this application. For example, even a feature that relates to a method can be combined with a feature that relates to a laser processing device, and vice versa. Further, a feature of an embodiment that relates to a

Laser processing device relates, can be combined with a corresponding feature, which relates to a method. With the disclosure of a method, an embodiment of a method or a function, one or more elements (for example optical elements) and / or actuators (for example in the form of an actuator arrangement) as well as a functionality of a control device that interacts with the actuators are to be regarded as disclosed, which for Execution of the method or the function are designed. Furthermore, with the disclosure of a function a

Device a corresponding method, which the function without

Device features defined as disclosed.

Unless otherwise stated, numerical values are to be understood as including a ± 5% window, i.e. H. For example, an indication of the number of 100 furrows comprises, according to one embodiment, a number of furrows within an interval of (100 ± 5%) = [95; 105] and one

According to one embodiment, a percentage of 50% comprises a

Percentage within an interval of 50% ± 5% = [47.5%;

52.5%]. According to a further embodiment are numerical values

including a ± 10% window.

According to one embodiment, a laser processing device is disclosed which is configured to produce a plurality of furrows in one surface. According to a further embodiment, the

Laser processing device has an optical diffraction arrangement which is set up to receive a laser radiation and to receive it

Generating an output radiation. According to a further embodiment, the laser processing device has an actuator arrangement for

Generating a relative movement between the output radiation and the surface. As a result, the output radiation (by removing material from the surface) creates the multitude of furrows in the surface. According to one embodiment, the output radiation has a plurality of

Intensity maxima, of which each intensity maximum generates a furrow of the plurality of furrows.

In accordance with embodiments of the subject matter disclosed herein, the laser processing device has a beam path which is set up to direct the output radiation onto the surface. The beam path can, for example, be a free space in which the

Propagates output radiation from the diffraction array to the surface. According to a further embodiment, the beam path can have one or more deflection elements, for example mirrors.

For example, the actuator arrangement can be set up to move the at least one deflection element and thereby generate the relative movement between the output radiation and the surface. According to a further embodiment, the actuator arrangement is set up to move the surface and / or the laser processing device or parts thereof.

According to a further embodiment, the beam path can have one or more focusing optical elements and / or one or more dispersing optical elements, for example optical lenses.

According to one embodiment, the plurality of intensity maxima only exist in a narrowly limited area along the beam path Beam path of the output radiation. It goes without saying that in this case the surface is positioned in this region of the beam path. In other words, according to one embodiment, the surface and the

Beam path positioned with respect to each other so that the surface lies in a region of the beam path in which the output radiation is the

Having a multitude of intensity maxima.

Accordingly, according to one embodiment, a method for

Creating a plurality of furrows in a surface can be one or more of the following embodiments. According to one embodiment, the method comprises directing a laser radiation onto an optical one

Diffraction arrangement for generating an output radiation which has a large number of intensity maxima. According to another

Embodiment, the method comprises directing the output radiation onto the surface. According to a further embodiment, the method includes generating a relative movement between the

Output radiation and the surface (for example, the

Output radiation generated during the relative movement). Through the

Relative movement between the output radiation and the surface, the plurality of furrows is generated, each intensity maximum generating one of the plurality of furrows.

According to one embodiment, directing the output radiation onto the surface comprises positioning the surface and the output radiation with respect to one another, so that the surface is in a region of the

The beam path lies in which the output radiation has the plurality of intensity maxima.

According to one embodiment, the optical element and / or the

Beam path and / or the actuator arrangement set up so that the plurality of grooves created by the output radiation are parallel grooves.

According to one embodiment, there is a cross-sectional dimension

(for example a depth) of 80% of the furrows, which is generated by the plurality of intensity maxima, to a mean value of

Cross-sectional dimension within a tolerance interval of ± 10% of the

Cross-sectional dimension. According to one embodiment, this is the

Mean value is the arithmetic mean over the relevant cross-sectional dimension of the plurality of furrows. According to one embodiment, the cross-sectional dimension can be a width of the furrows or a depth of the furrows.

According to one embodiment, the furrows in the surface form riblets, i. H. a structure which, compared to a smooth surface, reduces the flow resistance of the surface. In particular with regard to the application, the function, the shape, the dimensions, the properties, etc. of the riblets, express reference is made to WO 2018/197555 A1, the entire disclosure of which, in particular the dimensions and

Applications of the riblets, incorporated herein by reference.

As is customary for riblets, in one embodiment the furrows each have lateral walls. The adjacent walls of two adjacent furrows therefore form two mutually opposite flanks of a rib between the two furrows. In other words, according to one embodiment, the multiplicity of furrows creates a multiplicity of ribs on the surface, which, when dimensioned appropriately, act as riblets (ie reduce a flow resistance across the surface), for example as described in WO 2018/197555 A1 cited above is described. According to one embodiment, the flanks of the ribs enclose an acute angle. In particular, according to one embodiment, the ribs are tapered to a point. According to one embodiment, the ribs extend essentially parallel to one another and in particular parallel to a flow direction of an expected flow over the surface.

According to one embodiment, the diffraction arrangement has at least one optical element. If an optical element is mentioned below, it should be understood that, according to one embodiment, in the case of two or more optical elements, each of these optical elements can be configured according to one or more of the embodiments disclosed herein.

According to one embodiment, the at least one optical element (for example each optical element of the diffraction arrangement) is set up to generate a plurality of phase differences between a plurality of parts of the output radiation. According to a further embodiment, the at least one optical element is set up to pass through the

Generating the plurality of phase differences the plurality of

To generate intensity maxima in the output radiation. It goes without saying that the phase differences between each two parts of the

Output radiation for different parts of the output radiation im

Are generally different.

For example, according to one embodiment, the optical element is a diffractive optical element. For example, according to one embodiment, the diffractive optical element has a structure which generates the plurality of phase differences. According to a further embodiment, the diffraction arrangement has two or more diffractive optical elements. For example, in one embodiment, the diffraction arrangement has two or more (diffractive) optical elements (which, for example, are also referred to as phase masks), whereby the generation of Phase differences take place in several planes (Multi-Plane Light

Conversion, MPLC). According to a further embodiment, the

Diffraction arrangement a hologram. Starting from a desired intensity distribution of the output radiation, a diffractive optical element, an MPLC element or a hologram can be produced according to production methods known per se. The techniques described in the following documents may be mentioned here merely by way of example: EP 1 591 805 B1, US 5 073 007.

According to one embodiment, at least one of the at least one optical element of the diffraction arrangement is designed to generate the plurality of intensity maxima within a cross section of the output radiation that is smaller than the cross section of the laser radiation that falls on the diffraction arrangement. In other words, at least one of the at least one optical element of the diffraction arrangement is designed in order to achieve a focusing of the laser radiation as it falls on the diffraction arrangement. For example, according to one embodiment, the last optical element (viewed in the direction of propagation of the laser radiation) of the diffraction arrangement (i.e. the optical element which the

Output radiation generated) formed in this way. According to a

Embodiment, the cross section (also referred to herein as the beam diagonal) is defined by the greatest extent of the radiation perpendicular to the radiation direction.

Unless otherwise specified, the cross-section refers to the

Output radiation on the cross-section that the output radiation has on the surface. In other words, the cross section of the output radiation according to one embodiment corresponds to the cross section of the entire illumination spot (spot) that the output radiation generates on the surface (ie at a defined distance from the diffraction arrangement). The spot (i.e. the entire spot of illumination that the Output radiation generated on the surface) therefore includes the multitude of intensity maxima.

According to one embodiment, at least one further optical element, for example at least one focusing optical element and / or at least one diverging optical element, for example a lens, etc. can be arranged between the diffraction arrangement and the surface (i.e. in the beam path). For example, the at least one further optical element can be provided for at least one of the following functions: to focus or expand the output radiation; to scale the plurality of intensity maxima; in order to generate the intensity maxima in a desired configuration, if the diffraction arrangement was set up for generating the plurality of intensity maxima in the desired configuration with the at least further optical element; etc. According to one embodiment, the diffraction arrangement is set up (calculated) to generate the plurality of intensity maxima (in particular the spot with the plurality of intensity maxima) at a predetermined distance, possibly taking into account the at least one further optical element. According to one embodiment, the surface is arranged at the predetermined distance from the diffraction arrangement.

According to one embodiment, the plurality of intensity maxima (i.e. the plurality of intensity maxima which each generate one of the plurality of furrows) comprises at least 10 intensity maxima. For example, the plurality of intensity maxima comprises at least 50 intensity maxima or, according to other embodiments, at least 100, at least 200, at least 500 or at least 1000 intensity maxima. For example, the multitude of intensity maxima includes between 500 and 1500

Intensity maxima. According to one embodiment, the distance between the intensity maxima is nominally between 40 pm and 160 pm, for example 100 pm. It goes without saying that in the event that the furrows produce riblets in the surface, the spacing of the intensity maxima is adapted in order to achieve the desired spacing of the ribs. As explained, the desired spacing of the ribs (and thus the desired spacing of the intensity maxima, for example, depend on the flow velocity for which the riblets produce a desired reduction in flow resistance.

It goes without saying that the spacing of adjacent furrows of the plurality of furrows can in practice deviate from the nominal spacing of the intensity maxima, for example by ± 5%. For example, according to one embodiment, for a nominal spacing of the intensity maxima of 100 pm, a spacing between adjacent furrows can be between 90 pm and 110 pm.

According to one embodiment, the spot size is between 15 mm and 500 mm, for example between 30 mm and 200 mm. For example, the spot size for a 5 kW laser can be 120 mm. Furthermore can

for example the spot size is 70 mm, for example for a 2 kW laser. According to one embodiment, the spot has the spot size in a direction perpendicular to the relative movement.

According to one embodiment, the spot has a direction of minimum dimension and a direction of maximum dimension, the maximum dimension dmax according to one embodiment being a multiple of the minimum dimension dmin. For example, the maximum dimension dmax is F times the minimum dimension dmin, dmax = F * dmin, the factor F according to one embodiment being between 5 and 100, for example 40 (dmax = 40 * dmin). For example, the minimum dimension can be 3 mm and the maximum dimension 120 mm.

For example, according to one embodiment, the spot is essentially a rectangular or elliptical spot with the dimensions dmin * dmax, ie for example with a dimension of 3 mm * 120 mm. After the spot has the multiplicity of intensity maxima, denotes the spot size

(for example of an “essentially rectangular” spot) Dimensions (for example dmin, dmax) of a rectangle which can be circumscribed around the spot (or around the plurality of intensity maxima)

Embodiment, a spot size specified herein is the maximum

Dimension dmax of the spot.

According to one embodiment, the relative movement between the output radiation and the surface takes place in the direction of minimal dimension. This allows for a smaller minimum dimension for a given

Speed of the relative movement realizes a shorter illumination duration of the surface. The duration of illumination of the surface with the

According to one embodiment, output radiation is less than 40 ms, for example less than 10 ms. In particular, the

Illumination time of the surface with the output radiation less than 2 ms. According to one embodiment, the minimum dimension and the speed of the relative movement are adapted to the specified

Realize lighting duration. According to one embodiment, the speed of the relative movement is at least 100 mm / s,

for example in an interval between 100 mm / s and 2 m / s, in particular in an interval between 300 mm / s and 1 m / s. For example, the speed of the relative movement is nominally 500 mm / s or more.

According to one embodiment, the intensity maxima are arranged periodically, for example periodically in a row. According to a

Embodiment, each intensity maximum has a shape that deviates from a circular shape. For example, each intensity maximum of the plurality of intensity maxima has an elongated shape. The shape of a

The intensity maximum is defined here as usual, for example, by the shape of a line of equal intensity. According to one embodiment, the optical element is set up to work in reflection. In other words, according to one embodiment, the optical element is a reflective optical element. Through an optical element that works in reflection, a thermal

Load on the optical element can be reduced. In the case of an optical element which works in reflection, the structure which the

Phase difference generated, according to one embodiment

Be surface structure.

According to a further embodiment, the optical element has a body made of metal or of a semiconductor material. According to a

Embodiment, the body is formed from a metal with high electrical conductivity and / or a metal with high thermal conductivity, for example copper or gold. According to another

In the embodiment, the body is made of a corrosion-resistant metal (i.e. a metal that is resistant to corrosion),

for example from a suitable metal alloy or from a

Precious metal. According to a further embodiment, the body is formed from silicon. According to one embodiment, the body is formed from a single crystal. In this way, grain boundaries can have an influence on the

Properties of the optical element are avoided.

According to a further embodiment, the body is at least partially covered with a metal, in particular a corrosion-resistant metal

coated. According to one embodiment, the corrosion-resistant metal is a corrosion-resistant alloy or a noble metal, for example gold. Due to the corrosion-resistant metal, a high reflectivity of the optical element can be achieved over the long term. For example, the optical element can have a body made of silicon, which is connected to the metal

(e.g. gold) is coated. According to one embodiment, the body has a thickness in a range between 1 mm and 200 mm, for example between 5 mm and 50 mm. A greater thickness can allow a greater rigidity of the body and thus a higher accuracy of the optical element.

According to a further embodiment, the optical element has

(for example the body or, if a coating is arranged on the body, the coating) has a first surface with a cross section (for example a diameter) in a range between 20 mm and 500 mm, for example a diameter between 70 mm and 200 mm. According to one embodiment, the cross section (e.g. the

Diameter) defined by the largest extent of the first area

(for example a main surface of the optical element).

According to one embodiment, the optical element is structured on the first surface, wherein according to a further embodiment the structured surface is surrounded by a non-structured edge. According to a

Embodiment, the structured surface of the optical element can be formed by structuring the body (for example by engraving, etching, etc.), wherein a structure of the body obtained in this way is transferred to the coating according to one embodiment and thus the

Coating (if present) has a corresponding structure (i.e. the structured surface of the optical element). According to a

Embodiment, the width of the unstructured edge is between 2% and 20% of the cross section of the first surface. According to a

Embodiment, the structured surface is completely illuminated by the laser radiation. For this purpose, according to one embodiment, the

Laser radiation are expanded accordingly, for example under

Use of a beam expander, for example in the form of a

Lens group or in the form of a DOE. According to one embodiment, the laser processing device has a coolant flow path for cooling the optical diffraction arrangement (in particular for cooling the optical element), in particular a coolant flow path for a liquid coolant. For example, the optical element can have a cavity which forms at least part of the coolant flow path. According to another

Embodiment, the coolant flow path can be formed by a separate component which is connected to the optical element

is coupled in terms of heat transfer. According to one embodiment, the coolant flow path is arranged on a rear side of the body; H. on a second surface (for example a second main surface) of the body, which is arranged facing away from the structured first surface.

According to one embodiment, the output radiation forms an angle between 0 degrees and 50 degrees with a (mean) surface normal of the structured (first) surface of the body, for example an angle of 10 degrees.

According to one embodiment, the laser radiation forms with the

Surface normals of the structured (first) surface of the optical element an angle between 1 degree and 70 degrees, for example between 45 degrees and 60 degrees.

According to one embodiment, an angle between the laser radiation (i.e. an input radiation which strikes the diffraction arrangement) and the output radiation is between 20 degrees and 100 degrees, for example 50 degrees.

According to one embodiment, the optical element (in particular the last optical element in the direction of radiation is the optical Diffraction arrangement) calculated for a specific arrangement of the optical components of the laser processing device and the surface (in particular for a specific arrangement of the laser radiation, the optical element and the surface relative to one another). The calculation of the optical element for a specific arrangement of the optical components of the laser processing device and the surface is particularly advantageous if the optical diffraction arrangement consists of a single diffractive optical (DOE).

According to one embodiment, the laser radiation has a diffraction index M ² that is less than 1.5 (M ² <1.5). According to a further embodiment, the laser radiation has a diffraction index M ² <1.3 or M ² <1.1. The smaller the diffraction index, the more precise a desired one can be

Intensity pattern can be realized, showing the multitude of

Has intensity maxima.

According to one embodiment, the laser radiation is the laser radiation of a CO 2 laser. A CO2 laser has the advantage that it is available with high average powers, which in turn enables high processing speeds. For example, an average power of the laser radiation is at least 500 watts (W). According to a further embodiment, the average power of the laser radiation is at least 1 kilowatt (kW) or, according to yet another embodiment, at least 3 kW.

In return, however, a high average power requires a suitable design of the laser processing device and its parts in order to enable a reliable and stable operation of the laser processing device. Embodiments of the subject matter disclosed herein allow reliable and stable operation of the laser processing device at a high average power. According to one embodiment, the laser processing device has a laser source for generating the laser radiation. According to a further embodiment, however, it can also be provided that the

Laser processing device can be coupled to a laser source.

In summary, the present disclosure includes in particular the following embodiments and combinations of embodiments:

1. A laser processing device for producing a plurality of furrows in a surface, the laser processing device comprising:

an optical diffraction arrangement which is set up for

Receiving a laser radiation and then generating a

Output radiation, the output radiation being a variety of

Has intensity maxima;

an actuator arrangement for generating a relative movement between the output radiation and the surface, each intensity maximum generating one of the plurality of furrows.

2. The laser processing apparatus according to embodiment 1, wherein the

Diffraction arrangement has at least one optical element, in particular wherein the at least one optical element is set up to a

To generate phase difference between a plurality of parts of the output radiation.

3. Laser processing device according to embodiment 2, wherein the at least one optical element is set up to work in reflection.

4. Laser processing device according to embodiment 2 or 3, wherein the at least one optical element is a body made of metal or a

Has semiconductor material. 5. Laser processing device according to embodiment 4, wherein the body at least partially with a metal, in particular a

corrosion-resistant metal such as a corrosion-resistant alloy or a noble metal, is coated.

6. Laser processing apparatus according to any one of the preceding embodiments, wherein the optical element is a diffractive optical element.

7. Laser processing device according to any one of the preceding embodiments, wherein the plurality of intensity maxima comprises at least 10 intensity maxima, in particular at least 50 intensity maxima or at least 200 intensity maxima.

8. Laser processing apparatus according to any one of the preceding embodiments, further comprising:

a beam path configured to direct the output radiation onto the surface;

wherein the relative movement is a rectilinear movement; and the diffraction arrangement and / or the beam path are set up so that in each case two grooves of the plurality of grooves form a rib between them.

9. Laser processing device according to any one of the preceding embodiments, wherein the laser radiation is a CO 2 laser radiation.

10. Laser processing device according to any one of the preceding embodiments, an average power of the laser radiation being at least 500 W, in particular at least 1 kW. 11. Laser processing device according to any one of the preceding embodiments, further comprising a laser source for generating the laser radiation.

12. Laser processing device according to any one of the preceding embodiments, further comprising a coolant flow path for cooling the optical diffraction arrangement, in particular a coolant flow path for a liquid coolant.

13. A method of creating a plurality of furrows in a surface, the method comprising:

Directing laser radiation onto an optical diffraction arrangement for generating output radiation, the output radiation having a plurality of intensity maxima;

Directing the output radiation onto the surface; and

Producing a relative movement between the output radiation and the surface, each intensity maximum producing one of the plurality of grooves.

14. The method of embodiment 13, wherein generating the

Output radiation a reflection of the laser radiation on the optical

Includes diffraction arrangement.

15. The method according to any one of embodiments 13 or 14, wherein the plurality of intensity maxima comprises at least 10 intensity maxima.

16. Use of a laser processing device according to one of the

Claims 1 to 12 or a method according to one of Claims 13 to 15 for producing a plurality of parallel ribs, in particular riblets, on the surface. Embodiments of the objects disclosed herein allow a free choice of geometry for the furrows or the ribs between the furrows

(within the unit cell, for example, pointed tips of the ribs, flatter groove bottom). In contrast, the classic

Interference processing only ribs and furrows that are at least partially sinusoidal.

Furthermore, embodiments of the objects disclosed herein allow a more precise delimitation of the spot that the output radiation generates on the surface, in particular transversely to the processing direction. This can enable processing tracks of different spots to be strung together more effectively across the processing direction. In contrast to this, with classical interference with Gaussian rays, a Gaussian envelope is present. According to one embodiment, this envelope can be shaped into a rectangular function with the diffraction arrangement (or to a

Rectangular function approximated).

By generating the large number of intensity maxima in the

Output radiation through an optical diffraction arrangement (according to one embodiment through a single optical element, in particular a single diffractive optical element) can be compared to

conventional interference structuring (which in particular a

Beam splitting and a subsequent merging of the partial beams) result in a considerable simplification, since according to

Embodiments of the subjects disclosed herein, the beam shaping (the shaping of the envelope of the spot) and formation of the

Intensity maxima of fewer optical elements (for example only a single optical element) is caused.

In particular, the formation of the plurality of intensity maxima according to embodiments of the subject matter disclosed herein is not based on the generation of a path difference by individual ones, in a defined one Optical elements positioned at a distance from one another - in contrast to conventional interference structuring. This results in greater stability in an industrial environment, especially since fewer optical elements have to be held in a defined position relative to one another.

DETAILED DESCRIPTION

Exemplary embodiments of the subject matter disclosed herein are described below with reference to the drawings. It is noted that similar or identical elements or elements in different figures

Components are partially provided with the same reference numbers, or with reference numbers that differ only in the first digit. Features or components that are identical or at least functionally identical to the corresponding features or components in another figure are only described in detail when they appear for the first time in the following text and the description is replaced when these features and components (or the corresponding reference numbers) are not repeated. According to one embodiment, the above definitions apply to the following embodiments, and vice versa. Furthermore, the

Features and embodiments described above can be combined with the features and embodiments described below.

1 schematically shows a laser processing device 100 according to

Embodiments of the subjects disclosed herein.

According to one embodiment, the laser processing device 100 has an optical diffraction arrangement 102 which is set up for

Receiving a laser radiation 104 and generating a thereon

Output radiation 106. According to one embodiment, the

Laser radiation 104 with a mean surface normal of Diffraction arrangement 102 has an angle 103 which is between 1 degree and 70 degrees, for example an angle of 30 or 45 degrees. According to a

Embodiment, the direction of the surface normal is averaged over an active surface (for example a structured surface)

Diffraction arrangement 102, in particular (e.g. if the diffraction arrangement 102 has more than one active area) over an outer active area of the diffraction arrangement 102, which is illuminated by the laser radiation 104. As a result, the surface normal is also referred to herein as the mean surface normal. According to one embodiment, the output radiation 106 forms an angle 105 with the mean surface normal which is between 0 degrees and 70 degrees, for example an angle of 30 or 45 degrees.

The laser processing device 100 also has an actuator arrangement 108 for generating a relative movement between the output radiation 106 and a surface 110 of an object 112. According to one embodiment, the actuator arrangement 108 is arranged in a stationary manner, indicated at 114. According to a further embodiment, a processing assembly 116 is via a carrier 118 coupled to the actuator arrangement 108. According to a

Embodiment, the actuator arrangement 108 and / or the carrier 118 is formed by a robot arm. According to one embodiment, the

Actuator arrangement 108 and / or the carrier 118 on a movable

Stand for rough positioning (not shown in Fig. 1). This can be particularly advantageous in the case of large objects, for example aircraft parts. According to one embodiment, the lifting platform

have at least one actuator for moving the lift. According to one embodiment, the at least one actuator for moving the lifting platform can be part of the actuator arrangement 108. The means of

Actuator arrangement 108, the processing assembly 116 can be moved with respect to the object 112 or the surface 110 of the object 112 in order to move the output radiation 106 relative to the surface. According to another embodiment it can be provided that the object 112 is by means of an actuator arrangement is arranged movably, in addition or as an alternative to actuator arrangement 108.

For maintaining a distance between the diffraction arrangement 102 and the surface 110 in a predetermined distance range and / or for maintaining an orientation between the diffraction arrangement 102 and the surface 110 in a predetermined orientation range

A sensor arrangement 119 can be provided (pivoting range). According to one embodiment, the sensor arrangement has one or more sensors, for example at least one of a position sensor, a distance sensor, etc.

According to one embodiment, the object 112 is, for example, a part of an aircraft, for example a wing or a fuselage of the aircraft. According to another embodiment, the object 112 can be, for example, a rotor blade of a wind turbine. According to one embodiment, the object 112 is arranged in a stationary manner (indicated at 114), for example on a carrier (not shown in FIG. 1).

According to one embodiment, the laser processing device 100 has a laser output device 120 for outputting the laser radiation 104. According to one embodiment, a laser source for generating the

Laser radiation arranged in the laser delivery device 120. According to a further embodiment, the laser source is external to the

Laser delivery device 120 arranged. Especially with a

Embodiment in which the laser processing device 100, or a part of the laser processing device 100 is moved by the actuator arrangement 108 with respect to the surface 110, for example as shown in FIG. 1, the arrangement of the laser source can be external to the

Laser processing device (for example, for weight reasons) be useful. According to one embodiment, the laser processing device furthermore has a cooling device 124 for supplying the optical

Diffraction arrangement 102 or a coolant flow path 126 with a coolant 128.

Furthermore, according to one embodiment, the laser processing device 100 has a control device 122 for controlling further components of the laser processing device, for example the laser output device 120, the cooling device 124 and / or the actuator arrangement 108

The control of the further components by the control device 122 takes place according to one embodiment via a signal transmission coupling 130 of these further components to the control device 122,

for example as shown in FIG. According to one embodiment, the control device 122 is coupled to the sensor arrangement 119 for signal transmission (indicated at 130). According to a further embodiment, the control device 122 is set up to control one or more components of the laser processing device 100 in response to sensor signals 123 from the sensor arrangement 119. According to one embodiment, the control of components of the laser processing device (in particular the control of the further components and also in particular the

Control of the actuator arrangement) can be set up to maintain the distance between the diffraction arrangement 102 and the surface 110 in a predetermined distance range and / or maintain an orientation between the diffraction arrangement 102 and the surface 110 in a predetermined orientation range. According to one embodiment, the

Laser delivery device just a passive element. In this case, a signal transmission coupling with the control device can be dispensed with. According to one embodiment, the processing assembly 116 comprises one or more of the following components: the laser output device 120, the control device 122, the cooling device 124, the optical

Diffraction arrangement 102 and the sensor arrangement 119. For example, the processing assembly 116 comprises all of these components,

for example, as indicated schematically in FIG. 1 by the dashed line at 116.

According to one embodiment, the output radiation has a multiplicity of intensity maxima (not shown in FIG. 1), a cross section 132 of the output radiation 106 and in particular a cross section of the entirety of the multiplicity of intensity maxima being smaller than the cross section 134 of the laser radiation 104, which is incident on the diffraction optical assembly 102 falls. For example, according to one embodiment, the optical diffraction arrangement 102 has a focusing effect and thus reduces the cross section of the laser radiation 104 from the cross section 134 of the laser radiation 104 at the diffraction arrangement 102 to the cross section 132 of the output radiation 106 on the surface 110. According to one embodiment, the cross section 132 is also called Spot size of the output radiation 106 denotes. According to one embodiment, there is interference in the output radiation 106 and, as a result, the plurality of intensity maxima are formed.

It is pointed out that the diffraction arrangement 102, in addition to the output radiation 106, which has the multiplicity of intensity maxima, can also generate another radiation that is not used for processing the surface 110. The radiation that is not used (not shown in FIG. 1) can be masked out, for example, by suitable diaphragms so that it does not come out of the

Laser processing device 100 or the processing assembly 116 exits. FIG. 2 shows the surface 110 of the object 112 from FIG. 1 viewed from the line II-II in FIG. 1.

According to one embodiment, the output radiation 106 has a multiplicity of intensity maxima, some of which are labeled 136 in FIG. 2. As a result of the relative movement of the surface and the output radiation, indicated at 138 in FIG. 2, the intensity maxima 136 generate a multiplicity of parallel furrows in the surface, some of which are denoted by 140 in FIG. 2. The indicated direction 138 is the direction of movement of the output radiation 106 over the surface 110.

According to one embodiment, the shape of the intensity maxima deviates from a circular shape. In particular, according to one embodiment, one of the intensity maxima along a first direction 142, along which the intensity maxima are arranged next to one another according to one embodiment, has a first extension 143 that is smaller than a second

Extension 144 in a second direction 146, the second direction 146 being arranged perpendicular to the first direction 142. According to a

Embodiment, the relative movement 138 takes place between the

Output radiation 106 and the surface 110 along the second direction 146, for example as shown in FIG. 2.

According to one embodiment, the plurality of intensity maxima forms a spot of the output radiation or is formed by a spot of the output radiation. According to one embodiment, the spot has a minimum

Expansion in the second direction 146 (ie in the longitudinal direction of the groove 140) and has a maximum expansion perpendicular thereto (along the first direction 142). The greater the maximum extent of the spot in the first direction (perpendicular to the longitudinal direction of the furrows 140), the more furrows can be generated by the spot for a given furrow width. The more furrows a spot creates, the higher it can be Be the surface processing speed of the laser processing device 100.

FIG. 3 shows a portion of the plurality of grooves 140 of FIG. 2 in one

Cross-sectional view along the line III-III in FIG. 2.

According to one embodiment, the dimensions and the spacing of the furrows 140 are designed such that ribs 150 remain between the furrows 140. The ribs 150 are therefore formed from a material 148 which forms the surface 110 and which was removed in the region of the furrows 140 by the irradiation with the output radiation 106. According to one embodiment, the material 148 is a coating (for example a lacquer) which is arranged on a base part 152 of the object 112, for example as shown in FIG. 3.

4 shows a laser processing device 200 in accordance with embodiments of the subjects disclosed herein.

According to one embodiment, the laser processing device 200 has a cooling device 124 for cooling the diffraction arrangement 102.

According to one embodiment, the cooling device 124 is arranged externally to the machining assembly 116, for example as shown in FIG. 4. According to a further embodiment, the

Laser processing device coolant lines 127, through which coolant 128 can be conveyed to the diffraction arrangement 102. According to one embodiment, the laser processing device 200 has a

Heat exchanger 160 (for example a heat sink) with a coolant flow path 126 through which coolant 128 flows and is in thermal contact with diffraction arrangement 102

(for example, as shown in FIG. 4) in order to remove heat from the diffraction arrangement 102 with the coolant 128. According to one embodiment the heated coolant 128 is fed back to the cooling device 124 for cooling and again providing the coolant for the

Diffraction arrangement.

According to one embodiment, the laser processing device 200 has a laser source 162 which generates the laser radiation 104 and delivers it via a suitable light guide path 164 to the laser output device 120, from which the laser radiation 104 is directed to the diffraction arrangement 102

is delivered, for example as shown in FIG. According to a

In the embodiment, the light guide path 164 has a light guide and / or a suitable mirror arrangement for delivering the laser radiation 104 to the laser output device 120. For example, in the case of high powers of the

Laser radiation 104 and / or high requirements for maintaining the coherence of the radiation can be a mirror arrangement compared to a

Light guide be preferred. According to one embodiment, the laser source 162 is arranged externally to the processing assembly 116, for example as shown in FIG. 4.

According to one embodiment, the laser processing device 200 has one or more further optical elements 166, for example a focusing optical element 166 which focuses and / or focuses the output radiation 106 on a surface (not shown in FIG. 4)

Beam-expanding optical element 167, which expands the laser radiation 104 to the desired cross section 134 (see FIG. 1), for example at positions as shown in broken lines in FIG. 4.

The optical element 166 in FIG. 4 is an example of an optical element in a beam path 169 between the diffraction arrangement 102 and the surface on which the furrows are produced. For example, the optical element 166 can contribute to the fact that the beam path 169 is set up to direct the output radiation 106 onto the surface. For example, the at least one optical element 166 (which is also referred to herein as a further optical element) could be a mirror of a scanner, which moves the output radiation over the surface. In this case, the actuator arrangement would include at least one actuator of the scanner. According to another embodiment, the output radiation 106 is directed onto the surface exclusively by the

Diffraction arrangement 102. In other words, according to a

Embodiment of the beam path 169 free of optical elements, for example mirrors, lenses, etc.

According to one embodiment, the laser processing device 200 further comprises a control device 122, which is connected to components of the

Laser processing device 200 is coupled in terms of signal transmission (indicated by way of example in FIG. 4 for some components at 130).

According to one embodiment, the laser processing device 200 has an actuator arrangement 108 and a carrier 118. According to a

In the embodiment, the actuator arrangement 108 and the carrier 118 form at least part of a robot arm. According to one embodiment, connection paths between external components of the

Laser processing device 200 (e.g. cooling device 124, laser source 162, and control device 122) and the movable components of the laser processing device (e.g., the

Laser output device 120, the diffraction arrangement 102 and optional further optical elements 166, 167, in particular the components of the processing assembly 116) on the carrier 118 and / or the

Actuator arrangement 108 (for example on at least part of the

Robot arm) out, for example as shown schematically in Fig. 4.

By providing external components, for example the external components 122, 124, 162, a moving mass (ie the mass, which must be moved by the actuator arrangement 108) can be reduced. According to one embodiment, external components are components that are arranged externally with respect to the machining assembly 116. External components can, for example, be arranged (attached) to a base of a robot arm or also to the robot arm, in particular to a part of the robot arm which is arranged adjacent to the base of the robot arm (for example to one of the "lower" parts of the robot arm).

In general, it should be emphasized that while the placement of some components of the laser processing device described herein may be preferred for certain applications, within the scope of this disclosure the components of the laser processing device can be placed at any suitable location. For example, according to a

Embodiment, the diffraction assembly 102 removed from the

Machining assembly 116 be positioned, for example on a

Robotic arm or as an external component.

FIG. 5 shows a plan view of a diffraction arrangement 102 according to FIG

Embodiments of the subjects disclosed herein.

According to one embodiment, the diffraction arrangement 102 has a diffractive optical element 168 (hereinafter also referred to as an optical element for short). According to one embodiment, the diffractive optical element 168 has a first surface 172, which has an unstructured part 174 and a structured part 176. According to a

Embodiment, the unstructured portion 174 extends around the

structured part 176, for example as shown in FIG. 5 (and thus forms a non-structured edge in one embodiment). According to one embodiment, the diffractive optical element, in addition to generating the multiplicity of (relative) intensity maxima, also has a radiation-optical element Function, for example at least one of a focusing function, a beam directing function, etc.

FIG. 6 shows the optical element 168 of the diffraction arrangement 102 from FIG. 5 in a cross-sectional view.

According to one embodiment, at least the structured part 176 of the first surface 172 is formed from a metal, for example one

Coating 178. According to one embodiment, the optical element 168 has a body 170 and the coating 178 on the body 170. According to one embodiment, the body 170 is a structured one

Silicon wafer, wherein a surface structure 180 of the optical element 168 according to one embodiment is defined by the structure of the silicon wafer. It is pointed out that the surface structure 180 in FIG. 6 merely exemplarily and schematically shows the structured surface 176 of the optical element 168 and the surface 182 facing away from it

is intended to illustrate, but not necessarily a real one

Structuring an optical element 168 of the diffraction arrangement 102 in accordance with embodiments of the subjects disclosed herein.

According to one embodiment, the facing surface 182 is formed by a flat surface, for example by a flat surface of the body 170, for example as shown in FIG. 6. The flat, remote surface 182 can improve the thermal contact to a heat exchanger, for example a heat sink. According to one embodiment, the distance between structured surface 176 and facing surface 182 defines the thickness of optical element 168. According to one embodiment, the thickness of optical element 168 is averaged over structured surface 176 (mean thickness of optical element). According to one embodiment, the layer thickness of the coating 178 is less than 10% of the thickness of the body 170. Thus, according to one embodiment, the body 170 defines in

Essentially the thickness of the optical element 168. According to one embodiment, the area which the

Surface structure 180 forms, can be curved or, according to another embodiment, can be flat. In other words, before the surface structure 180 is produced, an initial surface can be curved or, according to another embodiment, can be flat. For example, a

Curvature of the output surface a beam-optical function of the optical element 168 can be achieved.

According to one embodiment, the diffraction arrangement 102 consists of a single diffractive optical element 168, for example a diffractive optical element, for example as shown with reference to FIGS. 5 and 6.

It should be noted that elements disclosed herein (such as

For example, a control device, a laser processing device, a laser output device, a cooling device, an actuator arrangement, an object, etc. are not limited to the dedicated entities as described in some embodiments. Rather, the subjects disclosed herein can be implemented in various ways while still providing the specific functionality disclosed.

It should be noted that each entity disclosed herein (for example device, element, feature and method step) is not limited to a dedicated entity as described in some embodiments. Rather, the articles described herein may be provided in various ways with various granularity at the device level or at the method level while still providing the

deliver specified functionality. It should also be noted that, according to embodiments, a separate entity for each of the herein

disclosed functions can be provided. According to others In embodiments, an entity can be configured to provide two or more functions as described herein. According to still other embodiments, two or more entities can be configured to together provide a function as described herein.

It is pointed out that the implementations described here in the drawings are only a limited selection of possible ones

Represent embodiment variants of the subjects disclosed herein. It is thus possible to combine the features of individual embodiments with one another in a suitable manner, so that for the person skilled in the art with the embodiment variants explicitly shown here, a large number of different embodiments can be viewed as disclosed. It should also be noted that terms such as “a” or “an” do not exclude a plurality. Terms such as “containing” or “having” do not exclude further features or method steps. The terms “comprising” or “containing” each encompass the two meanings “including, among other things,” and “consisting of”.

It should also be noted that while the exemplary

Laser processing device and the exemplary surface in the

Drawings shows a specific combination of several embodiments of the subject matter disclosed herein, any other combination of embodiments is also possible and is to be regarded as disclosed with this application.

An advantageous combination of embodiments of the subjects disclosed herein can be summarized as follows:

A laser processing device for producing a plurality of furrows in a surface has an optical diffraction arrangement which is set up to receive a laser radiation and to receive it

Generating an output radiation, the output radiation having a plurality of intensity maxima. An actuator arrangement is provided for generating a relative movement between the output radiation and the surface, each intensity maximum generating one of the plurality of furrows.

Claims

Patent claims

1. Laser processing device (100, 200) for producing a plurality of furrows (140) in a surface (110), the laser processing device (100, 200) comprising:

an optical diffraction arrangement (102) which is set up to receive a laser radiation (104) and to generate an output radiation (106) thereupon, the output radiation (106) having a plurality of intensity maxima (136);

an actuator arrangement (108) for generating a relative movement between the output radiation (106) and the surface (110), each intensity maximum (136) generating one of the plurality of furrows (140).

2. Laser processing device (100, 200) according to claim 1, wherein the diffraction arrangement (102) has at least one optical element (168), in particular wherein the at least one optical element (168) is set up to detect a phase difference between a plurality of parts of the

To generate output radiation (106).

3. Laser processing device (100, 200) according to claim 2, wherein the at least one optical element is set up to work in reflection.

4. Laser processing device (100, 200) according to claim 2 or 3, wherein the at least one optical element has a body (170) made of metal or a semiconductor material.

5. Laser processing device (100, 200) according to claim 4, wherein the body (170) at least partially with a metal (178), in particular a corrosion-resistant metal such as one

corrosion-resistant alloy or a precious metal, is coated.

6. Laser processing apparatus (100, 200) according to any one of

preceding claims, wherein the optical element (168) is a diffractive optical element.

7. Laser processing apparatus (100, 200) according to any one of

The preceding claims, wherein the plurality of intensity maxima comprises at least 10 intensity maxima (136), in particular at least 50

Intensity maxima (136) or at least 200 intensity maxima (136).

8. Laser processing apparatus (100, 200) according to any one of

preceding claims, further comprising:

a beam path (169), which is set up to the

Directing output radiation (106) onto the surface (110);

wherein the relative movement is a rectilinear movement; and the diffraction arrangement (102) and / or the beam path (169) are set up so that two furrows (140) of the plurality of furrows (140) form a rib (150) between them.

9. Laser processing device (100, 200) according to one of the preceding claims, wherein the laser radiation is a CO 2 laser radiation.

10. Laser processing apparatus (100, 200) according to any one of

preceding claims, wherein an average power of the laser radiation (104) is at least 500 W, in particular at least 1 kW.

11. Laser processing apparatus (100, 200) according to any one of

preceding claims, further comprising a laser source for generating the laser radiation (104).

12. Laser processing apparatus (100, 200) according to any one of

preceding claims, further comprising a coolant flow path (126) for cooling the optical diffraction arrangement (102), in particular a coolant flow path for a liquid coolant (128).

13. A method of creating a plurality of furrows (140) in one

Surface (110), comprising the method:

Directing a laser radiation (104) onto an optical one

Diffraction arrangement (102) for generating output radiation (106), the output radiation (106) having a plurality of intensity maxima (136);

Directing the output radiation (106) onto the surface (110); and generating a relative movement between the output radiation (106) and the surface (110), wherein each intensity maximum (136) generates one furrow (140) of the plurality of furrows.

14. The method of embodiment 13, wherein generating the

Output radiation (106) comprises a reflection of the laser radiation (104) on the optical diffraction arrangement (102).

15. Use of a laser processing device according to one of the

Claims 1 to 12 or a method according to one of Claims 13 to 14 for producing a plurality of parallel ribs, in particular riblets, on the surface (110).