DE102019204032A1 - Device for generating a spatially modulatable power density distribution from laser radiation - Google Patents

Abstract

In a device for generating a spatially modulatable power density distribution from several laser beams, a fiber holder with optical fibers arranged next to one another or a holder for several fiber plugs or fiber collimators with permanently connected optical fibers is used next to one another. Fiber exit surfaces of the optical fibers here form a one- or two-dimensional array. The laser beams emerging from the fiber exit surfaces are directed to a target plane via a common optical arrangement and a common scanning device and guided over the target plane. The device has a rotating device with which at least the fiber receptacle or receiving device or a corresponding distribution of the laser beams can be rotated about an axis running parallel to the laser beams. The device enables parallelized laser material processing with high flexibility.

Description

Technical field of application

The present invention relates to a device for generating a spatially modulatable power density distribution from laser radiation, in particular for laser material processing, in which several laser beams from optical fibers with an optical arrangement and a common scanning device can be directed onto a target plane and guided over the target plane.

In the area of laser material processing, the process speed is limited by various influences. On the one hand, the machining process itself can limit the speed. This is for example in the process of selective laser melting ( SLM ) the case in which the remelting of the metal powder can in practice take place at a maximum speed of approx. 1 m / s. On the other hand, the available laser power or the inertia of the scanning device can also limit the process speed. However, increasing the process speed is very important when laser processing is used in an industrial environment.

State of the art

The approach followed in laser material processing so far is to increase the process speed by parallelization, i.e. simultaneous processing with several laser beams. Different techniques are known for this parallelization.

It is known, for example, to split a laser beam into several partial beams by diffraction at a diffractive optical element (DOE) and to direct it onto the workpiece using a scanner. However, the partial beams cannot be modulated spatially and temporally separately from one another, so that the range of applications of this technology is limited.

For a broader application, processing based on several diode lasers arranged in parallel is also proposed. The beam is formed and guided for each diode laser using its own optical system and its own galvanometer scanner.

From the DE 102013011676 A1 a device and a method for additive component production are known in which a plurality of separate laser beams are guided in a machining head and directed next to one another and / or overlapping onto the machining plane. The processing head is moved over the processing plane with the aid of a movement device, while the intensity of the laser beams, which are separated from one another, can be modulated independently of one another in order to obtain the desired exposure geometry. A similar technique is also in the US 2017/0021454 A1 described.

The object of the present invention is to provide a device for generating a spatially modulatable power density distribution from laser radiation which enables parallelized laser material processing and which can be used even more flexibly.

Presentation of the invention

The object is achieved with the device according to claim 1. Advantageous configurations of the device are the subject of the dependent claims or can be found in the following description and the exemplary embodiments.

The proposed device has either a fiber arrangement of several optical fibers arranged next to one another in a fiber receptacle or a receiving device for several fiber plugs or fiber collimators with firmly connected optical fibers next to one another, with fiber exit surfaces of the optical fibers forming a one- or two-dimensional array in all cases. The device also has an optical arrangement with which laser beams emerging from the fiber exit surfaces of the optical fibers can be focused on a target plane, and a scanning device common to all laser beams, with which the laser beams can be guided or moved over the target plane. The device is characterized by a rotating device with which at least the fiber receptacle or receptacle device or a distribution of the laser beams resulting from the one- or two-dimensional array around an axis running parallel to the laser beams, preferably around an axis that is central to the distribution of the laser beams. Axis of symmetry, is rotatable.

With this structure, the proposed device enables the power density distribution of the laser radiation in material processing processes to be spatially scaled, for example during material removal by means of ultrashort pulse laser radiation or during selective laser melting or build-up welding, and in this way to increase the process speed. The laser material processing is carried out with several juxtaposed, possibly also at least partially overlapping, laser spots in the target plane, the individual laser beams being guided through a common beam shaping and using a common scanning device, for example a dynamic beam deflection unit, are guided over the target plane, which corresponds to the workpiece surface during laser material processing. The optical output power of the individual optical fibers can be individually modulated via the underlying laser sources or modulators connected upstream of them, so that individual laser spots can be switched on or off for processing. In this way, for example, the total track width of the intensity distribution generated in the target plane from the individual laser spots can be effectively varied.

In the proposed device, this intensity distribution or power density distribution in the target plane can be rotated by the rotating device and thus additionally adapted. This is particularly advantageous when generating an elongated power density or intensity distribution, in particular by using a correspondingly elongated or elongated single or multi-line array of the fiber exit surfaces of the optical fibers, since, for example, the total track width initially when guiding the intensity distribution in the target plane can be maintained unchanged in one direction and then in the direction perpendicular thereto by corresponding rotation of the intensity profile.

The rotation device can also be used to correct the rotation of the beam profile, which occurs as a side effect when the beam is deflected by rotating mirrors (e.g. 2D galvanometer scanner).

The rotation device can also be used to set the orientation of the beam profile in such a way that laser processing from two orthogonal directions is possible. This is the case with additive manufacturing processes such as Selective Laser Melting ( SLM ) advantageous to increase the strength of the additively manufactured components.

The rotating device can be, for example, a rotating device for the fiber receptacle or the receiving device for the fiber connector or fiber collimator, which then rotates it mechanically about a preferably central axis. A rotating device for the entire processing head is also possible. Another particularly advantageous possibility is to perform the rotation via an optical device which is arranged in the beam path of the laser beams and is rotated accordingly. This is preferably a Dove prism which is designed to be rotatable about its longitudinal axis by means of a suitable mechanism. Instead of the Dove prism, other optical arrangements can also be used, for example a suitable mirror arrangement which is designed to be rotatable accordingly. The rotation itself is preferably implemented using a suitable rotary drive, for example an electric motor.

The scanning device common to all laser beams can be a conventional dynamic beam deflection system such as a galvanometer or polygon scanner. A portal axis system can also be used to move the laser beams over the target plane. The scanning device can also be formed from a combination of different scanners.

In one embodiment of the proposed device, a fiber arrangement composed of several optical fibers running next to one another in a fiber receptacle is used. The optical fibers are arranged close to one another in the fiber receptacle, the distance between the fiber cores preferably being less than four times the thickness of the fiber cladding and preferably corresponding to twice the thickness of the fiber cladding. In such an embodiment, the optical arrangement then preferably has a collimator and focusing optics.

In an advantageous development, there are microlenses behind the fiber exit surfaces (in the direction of the laser beams), which are arranged and dimensioned in such a way that laser radiation emerging from the fiber exit surfaces overlaps in a first plane (in the beam direction of the laser beams) behind the microlenses. In this way, a coherent intensity distribution is generated from the individual laser beams in this first plane. This coherent intensity distribution is then preferably imaged in a reduced size on a second plane with the aid of first optics of the optical arrangement. Only after this second plane are the collimator and the focusing optics arranged for focusing in the direction of the target plane. In this way, a coherent intensity distribution is achieved in the target plane despite the distances between the individual optical fiber cores in the fiber receptacle and the associated reduced fill factor. The problem of a low fill factor occurs in particular when using singlemode fibers. When using multimode fibers, the fill factor is significantly higher due to the larger diameter of the fiber cores with the same distance between the individual fiber cores, so that in this case the arrangement of the microlenses and the first optical arrangement can be completely dispensed with.

The use of a fiber receptacle for many optical fibers lying close together has the disadvantage that an exchange of individual fibers is not possible or only possible with great effort. In a further embodiment of the proposed device, there is therefore a receiving device for several fiber plugs or fiber collimators with permanently connected optical fibers, i.e. for conventional connections to optical fibers, in particular permanently connected fiber collimators or standardized fiber stretchers (e.g. QBH). Following this recording device, an optical device is then arranged with which the mutual spacing of the laser beams emerging from the fiber exit surfaces of the optical fibers is reduced before they enter the optical arrangement and scanning device. This can be done for example by a suitable arrangement of several mirrors and / or prisms and / or lenses. This scaling device reduces the large distances between the fibers due to the conventional connections to the extent required for the proposed device. The particular advantage of this configuration is that the optical fibers and lasers remain modular and can be exchanged quickly if necessary.

The proposed device is particularly suitable for parallelized laser material processing. Of course, however, the device is not restricted to the field of laser material processing and can also be used for other applications in which parallel scanning of an object with laser radiation with a power density distribution that can be modulated is necessary or advantageous. By using a common beam deflection system or a common scanning device, the device has a low level of complexity, which is mechanically less susceptible, takes up less space and can be implemented more cost-effectively than arrangements with a large number of scanning devices. When using a polygon scanner, e.g. With a varying tilt angle of the individual mirror facets, a considerable increase in, for example, removal, structuring or marking processes can be achieved. This requires a corresponding modulation of the beam sources. The modulation can e.g. can be implemented using acousto or electro-optical switches that reach frequencies of over 1 MHz. The device is flexible with regard to the type of beam sources and thus also with regard to the field of application. For example, diode lasers coupled into multimode fibers, singlemode fiber lasers and ultra-short pulse lasers coupled into photonic fibers can be used.

Figure list

• 1 eine schematische Darstellung einer ersten Ausgestaltung der vorgeschlagenen Vorrichtung;
• 2 eine schematische Darstellung einer beispielhaften Faseranordnung in der Faseraufnahme der ersten Ausgestaltung;
• 3 eine schematische Darstellung der Faseranordnung der 2 mit zusätzlichen Mikrolinsen;
• 4 eine Querschnittsdarstellung der Anordnung der 3;
• 5 eine schematische Darstellung des optischen Systems bis zum Kollimator bei der Ausgestaltung der 3 und 4;
• 6 eine schematische Darstellung der Leistungsdichteverteilungen in den in 5 dargestellten Ebenen;
• 7 eine schematische Darstellung einer um die Symmetrieachse drehbaren Faseranordnung;
• 8 eine schematische Darstellung der Faseranordnung mit der Dreheinrichtung;
• 9 eine schematische Darstellung der parallelen Bearbeitung unter Einsatz eines Polygon-Scanners;
• 10 eine schematische Darstellung der Bearbeitungsspuren auf dem Werkstück bei der Bearbeitung gemäß 9;
• 11 eine schematische Darstellung der parallelen Bearbeitung unter Einsatz eines Galvanometer-Scanners;
• 12 eine schematische Darstellung der parallelen Bearbeitung unter Einsatz eines Portal-Achssystems;
• 13 eine schematische Darstellung zweier Beispiele der parallelen Bearbeitung unter Nutzung der Dreheinrichtung;
• 14 eine schematische Darstellung einer zweiten Ausgestaltung der vorgeschlagenen Vorrichtung;
• 15 eine schematische Darstellung einer dritten Ausgestaltung der vorgeschlagenen Vorrichtung;
• 16 eine schematische Darstellung der Ausgestaltungen der 14 und 15 mit der anschließenden Strahlskalierung und Drehung mit Hilfe eines Dove-Prismas;
• 17 eine zu 16 senkrechte Ansicht der Ausgestaltung der 14 und 15; und
• 18 eine schematische Darstellung der parallelen Bearbeitung beim Laserauftragsschweißen unter Einsatz einer Pulverdüse.

The proposed device is explained again in more detail below using exemplary embodiments in conjunction with the drawings. Here show:

• 1 a schematic representation of a first embodiment of the proposed device;
• 2 a schematic representation of an exemplary fiber arrangement in the fiber receptacle of the first embodiment;
• 3 a schematic representation of the fiber arrangement of FIG 2 with additional microlenses;
• 4th a cross-sectional view of the arrangement of 3 ;
• 5 a schematic representation of the optical system up to the collimator in the design of the 3 and 4th ;
• 6th a schematic representation of the power density distributions in the in 5 illustrated levels;
• 7th a schematic representation of a fiber arrangement rotatable about the axis of symmetry;
• 8th a schematic representation of the fiber arrangement with the rotating device;
• 9 a schematic representation of the parallel processing using a polygon scanner;
• 10 a schematic representation of the machining tracks on the workpiece during machining according to FIG 9 ;
• 11 a schematic representation of the parallel processing using a galvanometer scanner;
• 12 a schematic representation of the parallel processing using a portal axis system;
• 13 a schematic representation of two examples of parallel machining using the rotary device;
• 14th a schematic representation of a second embodiment of the proposed device;
• 15th a schematic representation of a third embodiment of the proposed device;
• 16 a schematic representation of the embodiments of 14th and 15th with the subsequent beam scaling and rotation with the help of a Dove prism;
• 17th one to 16 vertical view of the design of the 14th and 15th ; and
• 18th a schematic representation of the parallel processing during laser deposition welding using a powder nozzle.

Ways of Carrying Out the Invention

The proposed device enables laser material processing with several laser spots arranged next to one another, which are guided by a common beam shaping and are guided over the workpiece by means of a common deflection or scanning unit. 1 shows a schematic representation of a first exemplary embodiment of the proposed device. There are n optical fibers F _i arranged side by side in a one- or two-dimensional fiber arrangement. The ones made from these fibers F _i emerging laser beams 6th first pass through a rotating device 1 with which the distribution of the laser beams 6th can be rotated about an axis running parallel to the laser beams. This is followed by collimation in a collimator 2 and the dynamic beam deflection or beam guidance with a scanner 3 . The focus on the workpiece 5 takes place in this example via an F-Theta lens 4. The rotating device 1 is implemented in this example by means of a rotatable optical device, but can also be achieved by rotating the fiber receptacle or between the collimator 2 and scanner 3 respectively.

2 Figure a) shows an example of an arrangement of the optical fibers Fi in a row in the fiber receptacle A. . The fibers are in this fiber receptacle A. embedded and each have a coat M. and core K on, as is shown enlarged in detail in the right figure b) of the figure. The optical output power I _i (t) the individual fiber optic channels can be modulated individually so that individual laser spots can be switched on or off for processing. For example, the total track width of the laser processing on the workpiece can be effectively varied.

The fiber cores are arranged in the fiber arrangement with a distance Δx or Δy, the lower limit being the thickness of the cladding M. of the fibers is specified. With a typical cladding diameter of approx. 200 µm and a singlemode fiber core diameter of approx. 10 µm, direct imaging of the fiber cores would result K _i a low fill factor on the workpiece, ie large gaps between the machining tracks S _i on the workpiece. In the present embodiment, a (micro) lens is placed in front of each fiber to solve this problem ML attached, as in 3 is indicated schematically. The lenses ML _i this lens assembly LA in front of the fiber array FA are almost completely illuminated. The radiation behind the lenses is not completely collimated, so that in the plane E ' behind the lenses there is a significant overlap of neighboring radiation cones. This is in the sectional view of the 4th to recognize. This figure shows the assembled fiber arrangement FA with the lens arrangement placed in front of it LA . In the near field level E ' there is an almost complete distribution of intensity. E represents the exit plane of the laser radiation from the optical fibers F _i represent.

In the plane E ' the spot diameter is enlarged, for example by a factor 10 . Now becomes this level E ' by means of a compact, reducing lens system, for example consisting of two lenses L ₁ and L ₂ to the factor 10 again reduced, so lies in the plane E " an almost complete multi-spot distribution with a high fill factor and the original lateral width of the fiber exit areas. This structure is shown schematically in 5 shown. The power density distribution in the different levels E. , E ' and E " shows 6th in the partial figures a), b) and c). The level E " can go into the plane with the usual collimation and F-theta optics E " 'of the workpiece.

The microlenses behind the fiber facets (fiber exit surfaces) can form a (monolithic) lens arrangement LA which are summarized as a unit to the fiber receptacle A. can be mounted. This arrangement of fibers and lenses is referred to below as the lens-fiber arrangement FLA designated. The lenses and the lens arrangement can be made of diamond, for example. This allows the dimensions of the optical system to be significantly reduced, since this material, due to its excellent thermal properties, allows comparably high power densities on the optical surfaces.

In the case of multimode fibers, the fill factor, that is to say the ratio of core diameter to cladding diameter, is significantly larger, so that the above-described arrangement of microlenses and the optics for reducing the plane may be necessary E ' can be dispensed with. Instead, the fiber facets can be placed directly - or a plane in the near field of the facer facets - in the plane E " 'of the workpiece are mapped, for example directly via a collimator KO and F-theta lens.

The fiber arrangement FA or the fiber-lens arrangement is in the present example by means of a rotary device or axis of rotation THERE at least 90 ° around the axis of symmetry R. (see. 8th ) rotatable, as in 7th is shown schematically in partial figures a) and c). This rotatability makes the tracks S _i the laser beams can be superimposed crosswise in a simple manner on the workpiece with suitable guidance. The cross-overlaying is common in the SLM process, for example, in order to increase the component strength. In addition, continuous multi-spot trajectories can be driven by the rotation. Both variants are exemplified in the two partial figures a) and b) of 13 shown. The effective track spacing and the total track width can also be reduced by rotating the fiber arrangement (cf. partial figures b) and d) of the 7th ), which is becoming more important, especially when using multimode fibers. 7th shows an example of a rotation of the fiber arrangement through an angle θ = 45 °. If the fiber arrangement is aligned in the y direction, the track spacing Δy for θ = 0 ° is perpendicular to the feed direction VR maximum. A rotation through the angle θ> 0 ° causes the rotation along the feed direction VR a reduction in the effective track width. The individual tracks S _i are then also closer together or overlap more strongly. Will the fiber arrangement FA completely in the direction of the feed direction VR rotated (θ = 90 °), then all beam sources or spots are superimposed in one track. This can be used, for example, to cut a workpiece, for example a sheet metal, after laser structuring with a higher power density.

The manufacture of the fiber array FA can for example be done with the help of the selective laser etching process (SLE). In doing so, channels are created in the fiber receptacle, for example made of quartz A. generated, into which the optical fibers are then inserted and glued or fused.

Ordinary multi-mode and singlemode fibers and also photonic fibers (PCF), e.g. Hollow core fibers are used in the device. This means that a large number of laser beam sources can be used, for example CW fiber lasers for additive manufacturing and laser polishing or USP lasers for material removal and structuring.

The radiation reflected back from the target plane, for example from a metallic workpiece, can cause the fiber receptacle to heat up A. and the fibers lead. In order to dissipate the heat, the fiber receptacle can also contain cooling channels in addition to the fiber channels, which can also be introduced into the fiber receptacle using the SLE method. The cooling channels can, for example, be flowed through with (optionally colored) water. To prevent reflected radiation from being fed back into the fiber cladding, the fibers can be glued to the fiber receptacle (fashion stripping). Furthermore, measures for suppressing back reflections can also be integrated into the fiber arrangement, for example anti-reflective reflections and, if necessary, splicing of an anti-reflective quartz block.

8th shows in the partial figures a) and b) a schematic representation of the assembled lens and fiber arrangement FLA with the attached fiber bundle FB that means an axis of rotation THERE around the axis of symmetry R. is rotatable. The axis of rotation THERE can for example be driven by an electric motor.

In 9 is an embodiment for parallel material processing using a polygon scanner PS shown schematically. The through the fiber and lens arrangement FLA generated intensity distribution (in plane E ' ) is doing this over the lenses L ₁ and L ₂ reduced (cf. 5 and 6th ) and the laser beams then through the collimator KO collimated. The one-time focus ZS is variable (z-shift), so that no F-theta lens is required in this case. The mirror surfaces or mirror facets SF _i of the polygon scanner PS are tilted with increasing angles. The multi line Z ₁ on the workpiece WS is made by means of a mirror facet SF ₁ in feed direction VR traveled (part of figure a) of the 9 ). The multi line Z ₂ is due to the tilted mirror facet SF ₂ traversed (part of figure b) the 9 ) etc., like this in the 9 and 10 is indicated schematically. In 10 , a representation of the laser tracks on the workpiece WS , are the tracks S ₁ ... S _n from left to right in the feed direction VR drive through. At the end of the line Z ₁ the beam is then shifted to the beginning of line Z ₂ etc.

While the design of the 9 and 10 is particularly suitable for surface structuring and removal, shows 11 an embodiment for applications in the field of selective laser melting ( SLM ). Here the parallel processing is carried out using a galvanometer scanner GS shown. As in the previous example, pre-focusing takes place without an F-theta lens. The structure of the device is identical to that of the except for the different scanning device 9 . By rotating the fiber and lens assembly FLA with the help of the axis of rotation THERE In this embodiment, orthogonal tracks can be rotated by 90 ° in the process level E " '(Surface of the work piece WS ), as exemplified in the two partial figures a) and b) of the 11 is indicated. This can, for example, increase the component strength in SLM processes.

A third embodiment, especially for applications in the field of selective laser melting ( SLM ), is exemplified in part a) of the 12 shown. In this example, the parallel machining takes place by means of a portal axis system consisting of the linear axes P _x , P _y and P _z . The laser radiation is here via the optical system OS on the powder bed PB guided. The (metal) powder is along the tracks S _i merged. Through the means of rotation axis THERE rotatable fiber and lens arrangement, continuous curved paths can be driven, as shown in the right part of figure b) of 12 is indicated.

The proposed device can also be used for other applications, for example for build-up welding. An example of this application is in 18th shown schematically. The laser radiation from the fiber and lens arrangement FLA is done using the lenses L ₁ , L ₂ and the optical system OS by a suitably designed powder nozzle PD through onto the workpiece WS focused like this in the left part of the 18th is shown. By means of a powder jet that can optionally be spatially modulated PS is then the material order MAT with the help of the laser radiation on the workpiece WS welded on. This is in the right part of the 18th indicated in an enlarged view. The width of the material application can be adjusted by modulating the individual fiber channels. The nozzle PD has for this purpose an elongated outlet opening for the powder in order to generate a powder jet which is correspondingly elongated in cross section. The rotating device for rotating the elongated distribution of the laser radiation is not shown in the figure. The nozzle PD is rotated synchronously with the distribution of the laser radiation, preferably by rotating the entire processing head, which includes the fiber and lens arrangement FLA , the powder nozzle PD and carries the intermediate components.

Instead of the fiber receptacle with the fibers embedded in it, the radiation from optical fibers can also be combined with conventional connections to form a laser line. These can be, for example, permanently connected fiber collimators or standard plugs such as QBH. For this purpose, the proposed device has, in an advantageous embodiment, a receiving device for these standard plugs or fiber collimators. 14th shows a schematic representation of an exemplary structure when using fiber connectors 8th (upper part of the figure) or fiber collimators 9 (lower part of the figure) with firmly connected optical fibers F. . In both cases, there is a device following the receiving device for the fiber connector or fiber collimator 7th Required for beam scaling in order to guide the widely spaced laser beams closer together for later processing. The other components of the device correspond to those as they were already in connection with 1 briefly described.

15th shows two embodiments according to 14th , where instead of the collimator and the F-theta lens, a device 10 is used for focusing with a focus shifter.

In 16 is an exemplary setup for beam scaling and beam rotation of the 14th and 15th , so part of the device, shown again in more detail. The ones from the fiber connectors FS1 , FS2 , FS3 or associated fibers emitted by laser beams 6th are first in the collimators KO1 , KO2 , KO3 collimated and via a suitable mirror arrangement with the mirrors SP1 , SP2 and SP3 brought closer to each other to increase the beam fill factor. Further scaling in the x and y directions takes place via the subsequently suitably arranged prisms Pr1 to Pr4 . About the Dove Prism Pr5 in a corresponding axis of rotation THERE a rotation of the beam arrangement around the z-axis is then made possible. 17th shows the same structure again from the y-direction. These figures show an exemplary structure of the beam scaling device from the mirrors SP1 to SP3 and the prisms Pr1 to Pr4 to recognize through which the laser beams emerging from the fibers 6th be brought much closer to each other.

The in connection with the 14th to 17th The embodiments shown have the advantage that the fibers and / or the lasers used for coupling into the fibers can be exchanged quickly and easily at any time.

List of reference symbols

1

Rotating device

2

Collimator

3

scanner

4th

F-theta lens

5

workpiece

6

Laser beams

7th

Device for beam scaling

8th

Fiber connector

9

Fiber collimator

10

Focusing and focus shifter

F, F _i

Optical fibers

FA

Fiber arrangement

A.

Fiber absorption

I _i (t)

optical output power

M.

coat

K

core

LA

Lens assembly

ML, ML _i

Microlens

E, E ', E ", E"'

Levels

L ₁ , L ₂

lenses

KO

Collimator

FLA

Fiber-lens arrangement

S _i

Processing marks

THERE

Rotary axis or rotary device

R.

Axis of symmetry

VR

Feed direction

FB

Fiber bundle

ZS

Focusing unit

SF _i

Mirror facets

WS

workpiece

Z _i

Multi-lines

PS

Polygon scanner

GS

Galvanometer scanner

P _x , P _y , P _z

Linear axes of the portal axis system

OS

Optical system

PB

Powder bed

FS1-FS3

Fiber connector

KO1-KO3

Collimators

SP1-SP3

mirror

Pr1-Pr5

Prisms

PD

Powder nozzle

PS

Powder jet

MAT

material

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102013011676 A1 [0006]
• US 2017/0021454 A1 [0006]

Claims (12)

Device for generating a spatially modulatable power density distribution from laser radiation, in particular for laser material processing - a fiber arrangement (FA) consisting of several optical fibers (F) arranged next to one another in a fiber receptacle (A) or a receptacle device for several fiber plugs (FS) or fiber collimators (KO) with firmly connected optical fibers (F) next to one another, with fiber exit surfaces of the optical fibers (F) form a one- or two-dimensional array, - an optical arrangement (2, 4, 10) with which laser beams (6) emerging from the fiber exit surfaces of the optical fibers (F) can be focused on a target plane, - A scanning device (3) common to all laser beams (6), with which the laser beams (6) can be guided over the target plane, and - A rotating device (1) with which at least the fiber receptacle (A) or receiving device or a distribution of the laser beams (6) resulting from the one- or two-dimensional array can be rotated around an axis (R) running parallel to the laser beams (6) as the axis of rotation is. Device according to Claim 1 , characterized in that an optical device (7) is arranged following the receiving device, with which a mutual spacing of the laser beams (6) emerging from the fiber exit surfaces of the optical fibers (F) before they enter the optical arrangement (2, 4, 10) is reduced. Device according to Claim 2 , characterized in that the optical device (7) is formed by an arrangement of several mirrors (SP1-SP3) and / or prisms (Pr1-Pr4) and / or lenses. Device according to Claim 1 , characterized in that the optical fibers (F) arranged next to one another in the fiber receptacle (A) have a fiber core (K) and a fiber cladding (M), the distance between the fiber cores (K) being less than four times the thickness of the fiber cladding (M) and preferably corresponds to twice the thickness of the fiber sheath (M). Device according to Claim 4 , characterized in that the optical arrangement (2, 4, 10) has a collimator and focusing optics. Device according to one of the Claims 4 or 5 , characterized in that microlenses (ML) are arranged and dimensioned behind the fiber exit surfaces in such a way that the laser radiation (6) emerging from the fiber exit surfaces from adjacent optical fibers (F) overlaps in a first plane (E ') behind the microlenses (ML). Device according to Claim 6 , characterized in that the optical arrangement (2, 4, 10) also has optics (L ₁ , L ₂ ) which reduce an intensity distribution of the laser radiation present in the first plane (E ') to a second plane (E ") maps. Device according to one of the Claims 1 to 7th , characterized in that the scanning device (3) has a polygon scanner (PS), a galvanometer scanner (GS) or a portal axis system (P _x , P _y , P _z ). Device according to one of the Claims 1 to 8th , characterized in that the rotating device (1) has a Dove prism which is arranged in the beam path of the laser beams (6) and is rotatably mounted about its longitudinal axis. Device according to one of the Claims 1 to 9 , characterized in that the axis of rotation is an axis of symmetry of the fiber receptacle (A), the receptacle device or the distribution of the laser beams (6). Device according to one of the Claims 1 to 10 , characterized in that the fiber exit surfaces of the optical fibers (F) form a single-line array or an elongated multi-line array. Device according to one of the Claims 1 to 11 , characterized in that the rotary device (1) has a rotary drive.

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