Device for decoupling marginal radiation and laser processing head with the same

Abstract

Device (10) for a laser processing head for coupling out marginal radiation (26) of a laser beam, comprising: an aperture (30) with a central first aperture region (31) for transmitting laser radiation (24) and a second aperture region (33) surrounding the first aperture region (31) for coupling out the marginal radiation (26); and a cooling device (43) with a cooling volume (44) for a cooling medium, wherein the second aperture region (33) limits the cooling volume (44) and is configured to direct the coupled-out marginal radiation (26) into the cooling volume (44) by reflection, and wherein the coupled-out marginal radiation (26) is absorbed in the cooling device (43).

Description

[0001] The invention relates to a device for coupling out edge radiation from a beam cone of a laser beam and to a laser processing head with such a device. background

[0002] Laser processing systems have been used in the manufacturing industry for many years, for example, for laser welding, soldering, or welding. A laser processing head directs a laser beam generated by a laser source onto the workpiece to be processed. The laser processing head contains various optical elements for collimation, guidance, and / or focusing.

[0003] To prevent overexposure to optical elements in a laser processing head, apertures are often used to absorb laser radiation outside a specific beam cone. Especially at high laser powers, the edge of an absorbing aperture can become extremely hot, and applied absorbing layers can be damaged beyond a certain temperature threshold. Absorbing layers are therefore always subject to a performance limit.

[0004] DE 10 2021 122 833 discloses an aperture for a laser processing head designed so that laser radiation extending outside the beam bundle is reflected by a portion of the aperture and re-impinges on the aperture. A portion of the laser radiation extending outside the beam bundle is absorbed by the aperture. The heat absorbed by the aperture is transferred to a cooling device with a flowing cooling medium.

[0005] DE 10 20217 210 350 B3 describes a device for coupling out laser radiation, which comprises a diaphragm made of a transparent material with an aperture. The diaphragm has two total reflection surfaces that reflect the radiation coupled out through the diaphragm and guide it to an absorber. Summary of the invention

[0006] It is an object of the invention to provide a decoupling device for a laser processing head for decoupling edge radiation of a laser beam, in which over-irradiation of the optical elements and / or thermal overloading of the laser processing head is reduced or avoided.

[0007] It is a further object of the invention to provide a decoupling device for a laser processing head for decoupling edge radiation of a laser beam, which has a low overall height or extension in the axial direction.

[0008] To achieve at least one of these objects, a device for coupling out edge radiation from a laser beam according to claim 1 and a laser processing head comprising the same are proposed. Advantageous embodiments are the subject of the dependent claims.

[0009] According to one aspect of the present invention, a device for a laser processing head for coupling out edge radiation of a laser beam comprises: an aperture having a central first aperture region for passing laser radiation and a second aperture region surrounding the first aperture region for coupling out the edge radiation; and a cooling device having a cooling volume for a cooling medium, wherein the second aperture region delimits the cooling volume and is configured to guide the coupled-out edge radiation into the cooling volume by reflection, and wherein the coupled-out edge radiation is absorbed in the cooling device.

[0010] According to a further aspect of the present invention, a device for coupling out radiation from a beam cone of a laser beam comprises: a diaphragm consisting of a light-conducting material, wherein the diaphragm is arranged transversely to a beam axis of the laser radiation, wherein the diaphragm has a first, central region with a diaphragm opening or a light-transmitting region, wherein the diaphragm opening or the light-transmitting region defines a beam of an exit radiation, wherein the diaphragm has a second region which is arranged radially outside the first region and couples out radiation lying outside the beam of the exit radiation, wherein the second region reflects the coupled-out radiation and guides it to a cooling device, wherein the diaphragm delimits the cooling volume and is in contact with the cooling medium, and wherein the coupled-out radiation is absorbed in the cooling device.

[0011] The idea underlying the invention is that absorption of the laser radiation takes place directly in a cooling volume of a cooling device filled with a cooling medium in order to limit the angular range of the laser radiation. This means that there is primarily no absorption at a solid body (i.e. the aperture) with subsequent heat conduction via the solid body to the cooling device. The laser radiation is coupled out and transported via an aperture designed as an optical fiber, which guides the coupled-out laser radiation from the optical space of the laser processing head into a cooling volume of a cooling device by reflection. For this purpose, the aperture or the optical fiber itself is part of the boundary of the cooling volume and is thus in contact with the coolant contained in the cooling volume.In the device according to the invention, the aperture of the output coupling device therefore not only defines a beam of the output radiation, but also transmits the outputted edge radiation to the cooling medium. In contrast to conventional water cooling systems, the absorption of the outputted laser radiation takes place in the cooling volume, i.e., the absorbing surface is located in the cooling medium. This increases the efficiency of heat dissipation, allows a larger amount of heat to be dissipated, and minimizes the risk of damage to the absorbing surface due to thermal stress.

[0012] The device according to any of these aspects may have one or more of the following features: The first aperture region for the passage of laser radiation is arranged centrally or centrally to the second aperture region. In other words, the second aperture region surrounds the first aperture region in the radial direction. Since laser radiation is coupled out in an edge region of the laser beam, this coupled out or laser radiation to be coupled out is referred to as edge radiation. The edge radiation strikes the second aperture region, in particular an entrance region of the second aperture region, and enters the second aperture region (i.e. the edge radiation is coupled out) in order to be guided there by reflection from surfaces of the second aperture region in the second aperture region to the cooling volume. The edge radiation is absorbed in the cooling device, in particular on the surfaces that delimit the cooling volume.

[0013] The aperture is rotationally symmetrical about a central axis of the device or aperture.

[0014] The cooling device can surround the second aperture region in the radial direction. Surfaces that define the cooling volume can be provided with an absorption layer. For example, a housing of the device can define the cooling volume of the cooling device. In other words, the cooling volume can be formed within the housing. Inner walls of the housing that define the cooling volume can have an absorption layer for absorbing the coupled-out edge radiation.

[0015] The edge radiation can exit the second aperture region or enter the cooling volume of the cooling device via an edge surface or outer peripheral surface of the aperture, in particular the second aperture region. The edge surface can be cylindrical and / or rotationally symmetrical about the central axis.

[0016] The aperture, in particular the second aperture region, can be designed as an optical waveguide. The aperture, in particular the second aperture region, can be made of a light-conducting material. Preferably, the aperture can be made of glass, in particular quartz glass, and / or a material with a refractive index greater than air.

[0017] The second aperture region can be designed such that the outcoupled edge radiation is guided into the cooling volume by total internal reflection. In particular, a refractive index of the second aperture region and / or a geometry of the second aperture region can be selected to guide the outcoupled edge radiation into the cooling volume by total internal reflection.

[0018] The aperture, in particular the second aperture region, can be configured to decouple the edge radiation from the beam path and to couple it transversely to the beam axis into a volume with a cooling medium.

[0019] The first aperture region for passing laser radiation can be formed as an aperture or a region provided with an anti-reflection layer, or can comprise an aperture or a region provided with an anti-reflection layer. The anti-reflection layer can be formed on a surface of the first aperture region through which laser radiation enters the aperture and / or on a surface of the first aperture region through which laser radiation exits the aperture.

[0020] The second aperture region may comprise an entrance region to allow the incident edge radiation to enter the second aperture region through the entrance region. Thus, the edge radiation can be coupled out through the entrance region of the second aperture region, e.g., from the optical space of a laser processing head. The entrance region of the second aperture region may have an anti-reflection coating. The remaining surfaces of the second aperture region may be uncoated. Alternatively, all or some surfaces of the second aperture region, with the exception of the entrance region, may have a reflective coating, e.g., made of gold. In this case, the entrance region may be uncoated.

[0021] The device may comprise a housing in which the cover and the cooling device are arranged. For example, the housing of the device may limit the cooling volume of the cooling device. In other words, the cooling volume may be formed within the housing.

[0022] The housing is advantageously made of stainless steel, which prevents electrochemical corrosion.

[0023] The cover can be at least partially connected to the housing via at least one sealing element, e.g., via at least one adhesive connection, in particular made of a UV-curing adhesive, or a seal. The at least one sealing element can seal the cooling volume of the cooling device formed in the housing.

[0024] To prevent damage to the sealing element from the coupled-out laser radiation, a reflective coating can be applied to the aperture in the region of the at least one sealing element. In other words, the aperture can be provided with a reflective layer, e.g., made of gold, in an area adjacent to the at least one sealing element.

[0025] The at least one sealing element can comprise an adhesive connection and / or a seal. The cover can, for example, be received in the housing and / or connected to the housing via at least one seal. The at least one seal can seal the cooling volume of the cooling device.

[0026] To prevent damage to the seal caused by the coupled-out laser radiation, a reflective coating can be applied to the aperture in the area of ​​the at least one seal. In other words, the aperture can be provided with a reflective layer, e.g., made of gold, in an area adjacent to the at least one seal.

[0027] The device may comprise at least one absorption element arranged in the cooling volume of the cooling device. The absorption element may be configured to absorb at least a portion, in particular a majority, ie, more than half, of the coupled-out radiation. The absorption element may have an absorption layer, e.g., a black layer. The absorption element may be inserted loosely or detachably into the cooling volume of the cooling device.

[0028] The absorption element can be annular, i.e., an absorption ring. The absorption element can subdivide the cooling volume of the cooling device such that the marginal radiation entering the cooling volume cannot escape through the aperture. In other words, the absorption element can subdivide the cooling volume of the cooling device such that marginal radiation that enters the cooling volume is lost in the cooling volume or, in the event of reflection, strikes the absorption element(s) again.

[0029] In an advantageous embodiment, two absorption elements, in particular two absorption rings, are arranged in the cooling volume and are spaced apart from one another.

[0030] The housing may comprise two housing parts, in particular a lower housing part and an upper housing part, which are glued or detachably connected to one another. The cooling volume formed in the housing may be sealed by a seal arranged between the two housing parts.

[0031] At least one connection for connecting the cooling device to an external cooling circuit can be provided on the housing. At least one opening for the cooling medium to enter the cooling volume and / or for the cooling medium to exit the cooling volume can be provided on the housing.

[0032] The aperture may have a reflective coating in some areas of the second region in order to reflect the coupled-out radiation and direct it to the cooling device.

[0033] A second aspect of the present invention is directed to a laser processing head for laser processing a workpiece by means of a laser beam, which has at least one optical element and at least one device according to the invention for coupling out edge radiation of a laser beam.

[0034] The decoupling device can be arranged upstream of the optical element and / or downstream of an entry port for the laser beam, e.g., downstream of a fiber coupler, in the direction of propagation of the laser beam. This positioning of the decoupling device can prevent damage to the optical elements of the laser processing head and reduce its thermal load.

[0035] The device for decoupling can be arranged within an optical space or within a beam guide of the laser processing head, in particular in a region between an entry port for the laser beam (e.g. light exit from a light guide) and a first beam-forming and / or beam-guiding and / or beam-transmissive and / or beam-partially transmissive optical element.

[0036] The cooling device of the device can be connected to a cooling circuit of the laser processing head. Thus, the cooling medium can be fed into or taken from an external cooling circuit.

[0037] According to the present invention, the radiation coupled out by the aperture is transported by light conduction within the aperture directly to the cooling device. The coupled-out radiation is reflected at the boundary layers of the transparent aperture. By transporting the coupled-out radiation into the cooling medium by light conduction, heat absorption by the aperture body is avoided. By dissipating the coupled-out laser radiation via the light-conducting aperture directly to the cooling device, damage to the optical elements of the laser processing head due to overheating can be avoided. Furthermore, the thermal load on the laser processing head is reduced.

[0038] By means of the decoupling device according to the invention, laser radiation can be decoupled in a laser processing head outside of a specific beam cone or angular range (so-called edge radiation), with little or no absorption occurring at a first point of incidence of the edge radiation on the second aperture area. By avoiding or reducing absorption-based decoupling in the optical space of the laser processing head, the associated contamination due to outgassing and thermally induced surface damage can be avoided. Short description of the characters

[0039] The invention is described below using exemplary embodiments schematically illustrated in the figures of the drawing. In the figures: Fig. 1 a schematic representation of a laser processing head according to the invention, Fig. 2A and Fig. 2B schematic sectional view of first embodiments of the device according to the invention, Fig. 3A and Fig. 3B schematic sectional views of second embodiments of the device according to the invention, and Fig. 4 a schematic sectional view of a third embodiment of the device according to the invention. Detailed description

[0040] In the following, the same reference symbols are used for identical and equivalent elements, unless otherwise stated.

[0041] Fig. Figure 1 shows a schematic representation of a laser processing head 1 used for processing a workpiece W. The laser processing head can be, for example, a laser cutting head or a laser welding head. The laser processing head 1 has an entrance port 12 for laser radiation 22, which is supplied, for example, via a laser fiber optic cable 20.

[0042] Various optical elements are arranged in a housing 2 of the laser processing head 1, for example an optic 14 and a focusing optic 16. The optic 14 and the focusing optic 16 each comprise a lens or a lens group.

[0043] The optical elements 14, 16 focus and bundle the divergent laser radiation 22 into a convergent laser beam 19, which exits from the exit port 18 in order to thereby carry out machining of the workpiece W.

[0044] In the propagation direction after the entrance port 12, the divergent beam of the laser radiation strikes an outcoupling device 10, which decouples and removes edge radiation 26 from the laser radiation, so that only a defined portion of the laser radiation exits the outcoupling device 10 as exit radiation 24 and strikes the optics 14. The laser radiation striking the outcoupling device 10 is referred to as entrance radiation 22.

[0045] The detailed structure of the decoupling device 10 according to first embodiments will be explained with reference to Fig. 2A and Fig. 2B, which show a schematic vertical section through the decoupling device 10. The embodiment in Fig. 2A and the embodiment in Fig. 2B differ only in the shape of the aperture 30.

[0046] The decoupling device 10 is designed rotationally symmetrically to a central axis A. When the decoupling device is installed in a laser processing head, the central axis A of the decoupling device 10 runs coaxially to a beam axis of the laser radiation incident on the decoupling device 10 (so-called entrance radiation 22).

[0047] The outcoupling device 10 comprises a diaphragm 30 and a cooling device 43 surrounding the diaphragm 30. The diaphragm 30 splits the laser radiation incident on the outcoupling device 10, i.e., the incoming radiation 22, into an exit radiation 24 and an outcoupled edge radiation 26. The diaphragm 30 is configured as an optical fiber, so that laser radiation impinging on the diaphragm 30 is guided into the cooling device 43 based on the principle of total internal reflection, transverse to the beam axis or to the central axis A of the outcoupling device 10. The diaphragm 30 can be made of a transparent material, for example, glass.

[0048] The cooling device 43 encloses a radially outwardly located edge surface 34 of the aperture 30. The radially outwardly located edge surface 34 can also be referred to as an outer peripheral surface of the aperture 30. Thus, the aperture 30 is in direct contact with the cooling device 43, in particular with a cooling volume 44 defined in the cooling device 43.

[0049] A cooling medium, in particular water, circulates in the cooling volume 44. The cooling medium can, for example, be supplied via a cooling medium connection 42 provided in the housing 36 and discharged via another connection (not shown). The cooling circuit of the cooling device 43 of the decoupling device 10 can be connected to a cooling circuit (not shown) of the laser processing head 1.

[0050] The decoupling device 10 has a housing 36, which can comprise a lower housing part 38 and an upper housing part 40. The housing 36 can be made of stainless steel to prevent electrochemical corrosion. An annular pin 52 preferably protrudes from the lower housing part 38 and engages in an associated groove 54 in the upper housing part 40. An adhesive connection 50 can connect the lower housing part 38 to the upper housing part 40 as a sealing element. The cooling device 43 is arranged in the housing 36. The housing 36 can define the cooling volume 44 of the cooling device 43.

[0051] The housing 36 also accommodates the light-guiding aperture 30. The aperture 30 is arranged transversely to the beam axis of the laser radiation 22 entering from the entrance port 12, i.e., the aperture 30 extends in a plane perpendicular to the beam axis. The aperture 30 can be connected to the housing 36 via adhesive joints 46, 48. For example, the aperture 30 is adhesively bonded at its spaced-apart upper sides to the inner sides of the housing 36 via adhesive joints 46, 48. Furthermore, a stop 51 can be provided for positioning the aperture 30 in the housing 36 in the radial direction.

[0052] The aperture 30 has a centrally arranged first aperture region 31 for the passage of laser radiation. The first aperture region 31 for the passage of laser radiation can, for example, comprise or be an aperture opening 32. The aperture opening 32 can be formed as a hole made in the glass body. Alternatively, the first aperture region 31 for the passage of laser radiation can be a region of the aperture 30 provided with an anti-reflection layer so that the laser radiation can pass through. The anti-reflection layer can be formed at least on the laser beam entrance side of the aperture 30 in the first aperture region 31. The anti-reflection layer can additionally also be formed on the laser beam exit side of the aperture 30 in the first aperture region 31.

[0053] Adjacent to the first aperture region 31 in the radial direction is a second aperture region 33 which extends as far as the cooling volume 44 of the cooling device 43. The second aperture region 33 delimits the cooling volume 44 on one side, i.e. the second aperture region 33 is in contact with the cooling volume 44 or the cooling medium contained therein. The second aperture region 33 is designed to guide laser radiation entering the second aperture region 33 to the cooling device 43 by single or multiple reflection. The incident edge radiation 26 enters the second aperture region 33 and is reflected therein, such that the edge radiation 26 is decoupled in the second aperture region 33 and guided to the cooling device 43. The decoupled edge radiation 26 is reflected at boundary surfaces of the second aperture region 33.The second aperture region 33 thus functions as an optical waveguide and decouples the edge radiation 26, which strikes the second aperture region 33, by reflection, in particular by total internal reflection due to the different refractive indices of air and the material of the second aperture region 33, and guides it into the cooling volume 44. Via a radially outwardly lying edge surface 34 of the aperture 30 or of the second aperture region 33, the decoupled edge radiation 26 is guided into the cooling volume 44 of the cooling device 43, which is filled with cooling medium. The refractive indices of the edge surface 34 or of the second aperture region 33 and of the cooling medium are preferably coordinated with one another such that the laser radiation guided in the second aperture region 33 can enter the cooling medium through the edge surface 34 with almost no absorption. In the cooling device 43, in particular on surfaces of the cooling device orof the housing 36, which limit the cooling volume 44, the coupled-out edge radiation 26 is absorbed.

[0054] Thus, the first aperture region 31 or the aperture opening 32 defines a beam cone of the exit radiation 24. An edge radiation 26 extending outside the beam cone of the exit radiation 24, which strikes the second aperture region 33, is coupled out and guided into the cooling volume transversely to the beam axis of the laser radiation (or the entrance radiation or the exit radiation).

[0055] A cross-sectional area of ​​the second aperture region 33, with a cross-section running parallel to the central axis A and through the central axis A, can have the shape of a rectangle, a trapezoid, or a quadrilateral. The second aperture region 33 can have a first surface with an entrance region through which the incident edge radiation 26 enters the second aperture region 33. The first surface can extend perpendicular to the central axis A or to the beam axis. The second aperture region 33 can further have a second surface or reflection surface at which the edge radiation 26 entering through the entrance region of the first surface is reflected. The second surface can run parallel to the first surface (cf. Fig. 2A, Fig. 3A) or form an angle with the first surface (cf. Fig. 2B) or curved (cf. Fig. 3B). The second surface can form an edge with the first surface, which delimits the first aperture area 31 formed as aperture opening 32 (cf. Fig. 3B). In Fig. 2A shows a diaphragm 30 with a rectangular cross-section. Preferably, the lower housing part 38 extends further toward the central axis A than the upper housing part 36. The second diaphragm region 33 extends further toward the central axis A than the housing 36, in particular than the upper housing part 40. The area of ​​the first surface of the second diaphragm region 33 uncovered by the upper housing part 40 contains or defines the entrance region through which the incident edge radiation 26 enters the second diaphragm region 33.

[0056] Furthermore, as described below for Fig. 3, a region of the second aperture region 33 may be coated with a reflective layer 62, 64, in which the coupled-out edge radiation 26 is to be guided to the cooling device 43 by reflection. For example, a region of the second aperture region 33 may be coated with a reflective layer that is in contact with the adhesive joints 46, 48 and / or with the housing 36. The adhesive joints 46, 48 may also be formed as a reflective layer.

[0057] In particular, at least one surface of the second aperture region 33, i.e., the first surface and / or the second surface, can be at least partially coated with a reflective layer 62, 64. The entrance region of the second aperture region 33, which serves to couple out the incident edge radiation 26, can be uncoated or have an anti-reflective layer, so that the edge radiation 26 can enter the second aperture region 33.

[0058] While in Fig. 2A shows a diaphragm with a rectangular cross-section, in Fig. 2B shows a trapezoidal aperture 30. The first surface of the aperture 30 with the entrance area extends perpendicular to the central axis A or the beam axis. The second surface of the aperture can be a truncated cone surface. Thus, the thickness of the aperture 30 decreases in the radial direction towards the central axis. With the exception of the aperture shape - and optionally also the shape of the housing base 38 - the Fig. 2B shown aperture 30 have the same features as above Fig. 2A. In Fig. 2B, the lower housing part 38 is adapted to the shape of the second surface of the aperture 30, so that the second surface of the aperture 30 is supported by the lower housing part 38. Thus, the lower housing part 38 also has a region that approaches the upper housing part 39 toward the central axis A.

[0059] Fig. 3A and Fig. 3B show second embodiments of the decoupling device 10 according to the invention, which, with the exception of the fastening via adhesive connections, are like the decoupling devices 10 in Fig. 2A or Fig. 2B can be executed.

[0060] Instead of the adhesive connection, a circumferential seal 56 is arranged between the housing parts 38, 40 as a sealing element. The housing parts 38, 40 can be releasably connected to one another by fastening means, e.g., screws or similar. Furthermore, the cover 30 is accommodated between two seals 58, 59, which are received in grooves 60 of the housing 36. The seals 56, 58, 59 seal the cooling volume 44 of the cooling device 43.

[0061] At least in the area of ​​the seals 58, 59, the aperture 30 may have reflective layers 62, 64 to prevent damage to the seals 58, 59 by the coupled-out edge radiation 26. As in Fig. As shown in Figure 3, a region of the second aperture region 33 can be coated with a reflective layer 62, 64, in which the outcoupled edge radiation 26 is to be guided to the cooling device 43 by reflection. A region of the second aperture region 33 that serves to outcouple the edge radiation 26 can be uncoated or have an anti-reflective layer.

[0062] Fig. 4 shows a further embodiment of the decoupling device 10 according to the invention with at least one absorption element arranged in the cooling volume 44.

[0063] As in Fig. As shown in Figure 4, the housing comprises a lower housing part 38 and an upper housing part 40, which are connected to one another. Between the housing parts 38, 40 or between the housing parts 38, 40 and the cover 30, similar to Fig. 3A or Fig. 3B seals 76 may be arranged. Alternatively, the housing parts 38, 40 may be glued together.

[0064] The first aperture region 31 is designed as an aperture 32, the edge region of which diverges in the propagation direction of the laser radiation. This forms a second surface or reflection surface 72 that runs obliquely with respect to the axis A. The second aperture region 33 has a quadrangular cross-section.

[0065] The radially outer edge surface 34 of the aperture 30 is surrounded by the cooling device 43. The edge surface 34 of the aperture 30 borders the cooling volume 44 of the cooling device 43 and is in contact with the cooling medium contained therein. The cooling volume 44 can be part of an external cooling circuit. At least one absorption element, for example an absorption ring, is arranged in the cooling volume 44. Fig. 4 shows a first absorption ring 68 and a second absorption ring 70, which are spaced apart from one another. The absorption element, in particular the absorption rings 68, 70, has an absorbing coating to absorb a portion of the edge radiation 26 incident on them. The absorbing coating can be a black layer.

[0066] The edge radiation 26 enters the light-guiding second aperture region 33 of the aperture 30, is reflected by the reflection surface 72, and is guided radially through the aperture to the cooling device 43. In the cooling volume 44 of the cooling device 43, the coupled-out edge radiation 26a, 26 is absorbed by the absorption rings 68, 70.

[0067] Preferably, the first surface of the second aperture region 33 in the entrance region is provided with an anti-reflection layer 74 so that the incident laser radiation can enter the second aperture region 33. The remaining surfaces of the second aperture region 33 can be uncoated (see reference numeral 75 in Fig. 4).

[0068] The decoupling device 10 can also be as described with respect to Fig. 2A, Fig. 2B and Fig. 3A, Fig. 3B, wherein at least one absorption element, e.g. an absorption ring, is arranged in the cooling volume 44.

[0069] In all of the above-described embodiments of the outcoupling device 10 according to the invention, the light-guiding aperture 30 serves both to define a beam of the output radiation 24 and to optically transmit the output edge radiation 26 to the cooling device 43 or into the cooling medium. The edge radiation 26 output by the aperture 30 is transported by light conduction, i.e. by reflection, in particular total reflection, in the aperture 30 to the cooling device 43. By further conducting the output edge radiation 26 into the cooling medium 44, absorption of heat at the point of impact or entry on the aperture 30 is avoided. By dissipating the output laser radiation via the light-guiding aperture 30 directly to the cooling device 43, damage to the optical elements 14, 16 of the laser processing head 1 due to overexposure or overheating can be avoided.Furthermore, the thermal load on the laser processing head 1 is reduced. List of reference symbols 1 laser processing head 2 Housing of the laser processing head 10 Decoupling device 12 Entry port 14 Optics 16 Focusing optics 18 Exit port 19 convergent laser beam 20 laser light guides 22 Entrance radiation 24 Exit radiation 26 marginal radiation 30 aperture 31 First aperture range 32 aperture 33 second aperture range 34 Outer peripheral surface of the aperture 36 housings 38 Lower housing part 40 Upper housing part 42 Cooling medium connection 44 cooling volume 46 Adhesive bond 48 Adhesive bond 50 adhesive bond 51 stop 52 cones 54 grooves 56 Seal 58 Seal 59 Seal 60 groove 62 reflective layer 64 reflective layer 68 first absorption ring 70 second absorption ring 72 second surface or reflection surface 74 Anti-reflective coating 75 uncoated surface 76 Seal A central axis W workpiece QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 122 833

[0004] DE 10 20217 210 350 B3

[0005]

Claims

[1] Device (10) for a laser processing head for coupling out edge radiation (26) of a laser beam, comprising: a diaphragm (30) with a central first diaphragm region (31) for the passage of laser radiation (24) and a second diaphragm region (33) surrounding the first diaphragm region (31) for coupling out the edge radiation (26); and a cooling device (43) with a cooling volume (44) for a cooling medium, wherein the second aperture region (33) delimits the cooling volume (44) and is designed to guide the coupled-out edge radiation (26) into the cooling volume (44) by reflection, and wherein the coupled-out edge radiation (26) is absorbed in the cooling device (43). [2] Device (10) according to claim 1, wherein the first aperture region (31) for passing laser radiation (24) comprises an aperture (32) or a region provided with an anti-reflection layer. [3] Device (10) according to one of the preceding claims, wherein the second aperture region (33) comprises an entrance region for allowing the incident edge radiation (26) to enter the second aperture region (33) through the entrance region, and wherein the entrance region of the second aperture region (33) has an anti-reflection layer (74). [4] Device (10) according to one of the preceding claims, wherein the second aperture region (33) comprises an entrance region to allow the incident edge radiation (26) to enter the second aperture region (33) through the entrance region, and wherein surfaces of the second aperture region (33) with the exception of the entrance region have a reflection layer (74). [5] Device (10) according to one of the preceding claims, wherein the second aperture region (33) is designed such that the coupled-out edge radiation (26) is guided into the cooling volume (44) by total reflection. [6] Device (10) according to one of the preceding claims, wherein the device (10) comprises a housing (36) in which the aperture (30) and the cooling device (43) are arranged. [7] Device according to claim 5, wherein the housing (36) is made of stainless steel. [8] Device according to claim 5 or 6, wherein the aperture (30) is connected to the housing (36) via at least one sealing element (46, 48, 58, 59), in particular an adhesive connection (46, 48) and / or a seal (58, 59), for sealing the cooling volume (44). [9] Device according to claim 7, wherein the aperture (30) has a reflective layer (62,64) in a region of the at least one sealing element (46, 48, 58, 59). [10] Device according to one of the preceding claims, wherein the cooling device (43) has at least one absorption element (68, 70) for absorbing the coupled-out edge radiation (26), which absorption element is arranged in the cooling volume (44). [11] The device of claim 7, wherein the at least one absorption element (68,70) comprises two spaced-apart absorption rings (68,70). [12] Device according to one of the preceding claims, wherein inner walls of the housing (36) delimit the cooling volume (44) and have an absorption layer for absorbing the coupled-out edge radiation (26). [13] Device according to one of the preceding claims, wherein the aperture (30) consists of glass, in particular quartz glass, and / or of a material with a refractive index greater than that of air. [14] Laser processing head (1) for laser processing a workpiece by means of a laser beam, comprising: at least one optical element (14,16), and at least one device (10) for coupling out edge radiation (26) of the laser beam according to one of the preceding claims, wherein the device (10) is arranged in the propagation direction of the laser beam in front of the optical element (14, 16) and / or after an entry port (12) of the laser processing head (1) for the laser beam. [15] Laser processing head (1) according to claim 14, wherein the cooling device (43) of the device (10) is connected to a cooling circuit of the laser processing head.

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