Laser machining head with a scanner unit or a scanner assembly

Abstract

The invention relates to a laser machining head (20) with a scanner unit which comprises: a mirror unit with a scanner mirror (242), said mirror unit having a groove (2432) which runs in the circumferential direction; a frame (241) which can be secured in a machining head (20) of the laser machining system (10), said mirror unit being movably mounted in the frame (241); and an annular elastic seal element (245), wherein the seal element (245) is secured to the frame (241) on the outer circumference of the seal element and engages with the circumferential groove (2432) on the inner circumference of the seal element. The invention additionally relates to a seal element (245) for a scanner unit and to an additional laser machining head with a scanner assembly (24).

Description

[0001] Laser processing head with a scanner unit or a scanner arrangement

[0002] Field of the invention

[0003] The present invention relates to the field of laser processing of workpieces, preferably the laser cutting of metallic workpieces. In particular, the invention relates to a laser processing head, in particular a laser cutting head, with a scanner unit or a scanner arrangement for dynamically deflecting a laser beam in the laser processing head.

[0004] State of the art

[0005] Scanner systems in which a laser beam is dynamically deflected within a laser processing head by the controlled tilting of one or more scanner mirrors are state of the art. For example, it is known to arrange a deflection mirror in the collimated beam guidance area of ​​the laser processing head, which can be tilted independently and dynamically about both transverse axes. The highly integrated design comprises the mounted scanner mirror as a rotor assembly with four magnet pairs distributed around the circumference, including an iron yoke. The rotor is suspended via four flexurally articulated arms and is deflected or tilted about its initial position by four coils (stator) positioned opposite the magnets. During the movement of the scanner mirror, particle formation can occur - particularly due to abrasion between moving components of the assembly.In order to meet the cleanliness requirements in the laser processing head, which essentially allow no adhering contaminants in the optical chamber, the semi-clean rear chamber of the scanner assembly must be effectively shielded from the optical chamber of the laser processing head.

[0006] DE102016210698A1 discloses an arrangement for EUV lithography in which at least one reflective optical element is movably mounted in a housing. A sleeve at least partially encloses the holder and the base body of the optical element and seals off an actuator chamber from an optics chamber. The sleeve has at least one flexible section to enable the movement of the optical element. The flexible section can be formed by a flexible plastic component. For attachment, the sleeve can be glued to the base body or fastened with a force-locking or positive-locking connection, for example, clamped with a spiral spring or a clamping ring.

[0007] WO2019145536A1 describes various variants of how a laser beam can be moved with high frequency and short distance within the nozzle of a laser processing head, among other things with the help of a scanner mirror.

[0008] EP4000789A2 describes an optical device comprising a carrier and a scanner mirror movably mounted thereon. A sealing membrane forms an airtight connection between the scanner mirror and the carrier.

[0009] The present invention is based on the object of improving the state of the art. In particular, it is intended to provide effective shielding of the optical chamber of a laser processing head from the acroric or drive chamber of a scanner unit or scanner assembly. In doing so, the influence on the movement dynamics of the scanner mirror is to be minimized. Furthermore, the suitability of existing scanner systems for use in multi-kilowatt laser cutting systems is to be improved.

[0010] The invention

[0011] To achieve the object underlying the invention, according to a first aspect, a laser processing head, in particular a laser cutting head, with a scanner unit is provided. The scanner unit comprises a mirror unit with a scanner mirror, wherein the mirror unit has a circumferential groove. The mirror unit can preferably have a mirror mount arranged on the outer circumference of the scanner mirror. The scanner mirror can preferably be firmly connected to the mirror mount, for example by an adhesive connection. The circumferential groove can then preferably be arranged on the outer circumference of the mirror mount.Typically, a laser processing head comprises at least one entrance opening for the laser beam, an optical chamber in which the laser beam is guided through the laser processing head by means of optical elements, in particular lenses and / or mirrors, and an exit opening for the laser beam to exit the laser processing head. The scanner unit, with the scanner mirror as the beam-guiding optical element, is then arranged adjacent to the optical chamber of the laser processing head.

[0012] The scanner unit comprises a frame that can be mounted in the laser processing head, with the mirror unit being movably mounted in the frame. In particular, the frame and the mirror unit can be arranged in a common plane of the scanner unit, with the frame laterally surrounding the mirror unit. The frame can, in particular, form a lateral housing for the scanner unit.

[0013] The scanner unit further comprises an annular, elastic sealing element. The sealing element is attached to the frame along its outer circumference and engages the circumferential groove along its inner circumference. The sealing element is preferably flat.

[0014] The proposed solution allows for a particularly compact and lightweight design of the scanner unit in the laser processing head. The sealing element effectively seals the inherent gap between the mirror unit and the frame against the passage of particles. Particles can be generated by the relative movements of the mechanical components of the mirror suspension and a drive unit, which is preferably arranged between the frame and the mirror unit and is designed to tilt the mirror unit. The sealing element shields the optical chamber of the laser processing head from the movable drive components of the scanner unit, thus reducing the security against optical failure due to contamination. The seal also opens up the possibility of applying a cooling gas to the mirror unit and / or the drive unit on a rear side of the scanner unit facing away from the optical chamber.This option is particularly advantageous when the scanner unit is used in a multi-kilowatt laser processing system.

[0015] The scanner mirror including the mirror mount and the drive unit can, for example, be designed as described in EP4000789A2, wherein the magnet pairs of the scanner drive are preferably arranged on the mirror mount.

[0016] The sealing element can preferably have a wave-shaped cross-section. The wave-shaped cross-section allows the deformation stiffness of the sealing element, which can also be referred to as a sealing membrane, to be reduced. This reduces the resistance when the mirror unit tilts, and improves the dynamics of the scanner unit. In particular, the sealing element can have at least one wave in its cross-section, which is designed such that it remains present even when the mirror unit is fully deflected.

[0017] The circumferential groove of the mirror unit can preferably have a cross-section that tapers towards the groove base. In this case, the groove base refers to the deepest point of the groove, i.e., in the case of a cylindrical mirror unit, the point at which the groove has its smallest diameter. In particular, the circumferential groove can have a trapezoidal cross-section. Furthermore, the sealing element can have a first thickened portion along its inner circumference, which is designed to be complementary in shape to the groove. In the present case, this is to be understood in particular that the thickened portion is wedge-shaped or trapezoid-shaped, with the outer bevels having essentially the same inclination as the outer walls of the groove. The engagement bevels of the thickened portion and the groove ensure an improved positive and adhesive fit of the snap connection between the sealing element and the mirror unit.Furthermore, a trapezoidal connection shape has proven particularly suitable with regard to the desired mass reduction. It can be particularly advantageous if the first thickening of the sealing element is wider than the groove in the groove base. This ensures that the sealing element engages or snaps into the groove with a precise fit.

[0018] Furthermore, it may be preferred that an inner circumference of the sealing element in a relaxed state is smaller, in particular by at least 2% and / or by at most 20% smaller, than a circumference of the groove in the groove base. For example, the inner circumference of the sealing element may be approximately 10% smaller than the circumference of the groove base. In this way, when installed in the scanner unit, the sealing element is under tension along its inner circumference and is pressed into the groove.

[0019] The sealing element can also be glued to the mirror unit along its inner circumference within the groove. In particular, the thickened portion of the sealing element along the inner circumference can be coated with adhesive when inserted into the groove. This bonding can further improve the adhesion of the sealing element in the groove and thus the sealing effect.

[0020] The sealing element can have a second thickening along its outer circumference. The second thickening can be clamped along an inner circumference of the frame. The second thickening can, for example, have a circular cross-section. To form the clamped connection with the sealing element, the frame can have a circumferential recess along its inner circumference, into which the second thickening can be received and secured by means of a clamping ring.

[0021] To achieve the object underlying the invention, a second aspect provides a sealing element for the scanner unit of a laser processing head according to one of the variants described above. The sealing element comprises an annular base body made of an elastic material, wherein the base body has a first, in particular trapezoidal, thickened portion along its inner circumference and a second, in particular circular, thickened portion along its outer circumference. The shape specifications of the thickened portions each refer to the shape of the cross-section in the circumferential direction of the base body.

[0022] In a relaxed state of the sealing element, the base body can preferably have a wave-shaped cross-section. By forming at least one wave in the base body of the sealing element, the resistance to the movement of a mirror unit with which the sealing element is engaged is reduced. Particularly preferably, the base body can have at least one wave in cross-section with an inner radius of at least 0.5 mm and / or of at most 2 mm, preferably of approximately 1 mm to 1.5 mm. The wave can be formed in the base body optionally as an elevation or a depression. The wave should generally be as small as possible in order to minimize the mass of the base body. Overall, the wave can preferably be designed such that it is just still present during maximum deformation of the base body during use in a scanner unit according to the invention.

[0023] The base body of the sealing element is preferably made of silicone. Alternatively, the sealing element can also be made of another, particularly non-outgassing, plastic, such as polytetrafluoroethylene (PTFE, also known as Teflon) or fluororubber (FKM). Due to its lower density compared to FKM and the resulting overall lower weight, silicone has proven particularly suitable for this application. Silicone also offers advantages over other materials in terms of its hardness, its minimal injection- or moldable material thickness, its impact resilience, and its elastomeric properties.

[0024] A thickness of the base body may preferably be at least 0.2 mm and / or at most 0.8 mm, preferably about 0.6 mm.

[0025] For example, a sealing element according to the invention can be manufactured from silicone by vacuum casting. The sealing element can be translucent, have a Shore A hardness of <50, in particular approximately 20, be 0.6 mm thick, and / or have a mass of >20 g, preferably <2 g, for example approximately 0.7 g.

[0026] To achieve the object underlying the invention, according to a third aspect, a laser processing head, in particular a laser cutting head, with a scanner arrangement is provided. The scanner arrangement comprises a scanner unit with a mirror unit comprising a scanner mirror and a frame, wherein the mirror unit is movably mounted in the frame. Furthermore, the scanner arrangement comprises a diaphragm with a diaphragm opening, wherein the diaphragm is fastened to the frame and wherein a smallest diameter of the diaphragm opening is smaller than an aperture of the scanner mirror. The diaphragm and the mirror unit are spaced apart from one another in the axial direction by a gap, wherein a minimum gap width is at most 2 mm, preferably at most 1 mm, more preferably approximately 0.8 mm. The axial direction in the present case means a direction parallel to the surface normal of the scanner mirror in a rest position, ora direction perpendicular to a bearing plane of the aperture.

[0027] The gap ensures the necessary freedom of movement for the mirror unit and is simultaneously so small that it prevents particles from escaping from the scanner assembly into the optical chamber of the laser processing head, where the scanner assembly is integrated. In other words, the aperture forms a labyrinth seal with the scanner unit.

[0028] The scanner mirror including the mirror mount and the drive unit can, for example, be designed as described in EP4000789A2, wherein the magnet pairs of the scanner drive are preferably arranged on the mirror mount.

[0029] The scanner arrangement can be designed, in particular, for use in a laser cutting head and thus for guiding a laser beam with a power of several kilowatts, in particular of at least 0.3 kW, preferably of at least 4 kW, even more preferably of at least 10 kW. To minimize the gap between the aperture and the mirror unit, the aperture can have a narrow, circumferential collar on its side facing the mirror unit, in particular at its smallest opening diameter, which points toward the mirror unit. The collar increases the sealing effect of the labyrinth seal.

[0030] The scanner unit can, in particular, be designed like the scanner unit of the laser processing head according to one of the variants described above, and thus have a sealing element between the frame and the mirror unit. According to this configuration, the cover can also serve as beam protection for the sealing element. A combination of the sealing element and the cover can thus improve the longevity of the sealing function.

[0031] The scanner arrangement can further comprise a cover that can be fastened to a side of the frame opposite the aperture and that covers an opening formed by the frame of the scanner unit. The cover can preferably protrude into the frame at the rear of the mirror unit, such that a gap formed between the cover and the rear of the mirror unit has a smallest gap width of at most 3 mm, preferably at most 0.7 mm. In a configuration with a sealing element, the scanner arrangement forms a drive chamber of the scanner unit, in which the movable drive components for the mirror unit are arranged and which is delimited in the direction of the optical chamber by the sealing element, laterally by the frame, and at the rear by the cover.

[0032] The cover can be mounted laterally to the mirror mount of the scanner unit at a distance of up to 2 mm, preferably up to a maximum of 1 mm, even more preferably up to a maximum of 0.7 mm. The aperture and / or the cover can each be made of a material with good heat conduction properties, for example a metal or a metal alloy. In particular, the aperture and / or the cover can be made of steel. In this way, the aperture and / or the cover can additionally be used as cooling elements for the scanner arrangement. Due to the small spacing from the mirror unit, heat can be dissipated from the mirror unit, i.e. from the scanner mirror and / or from the mirror mount, by free or forced convection.

[0033] The aperture and / or cover can also be connected to a cooling system, thus providing active cooling for the scanner assembly. For this purpose, one or more cooling channels can be arranged in the aperture and / or cover, for example, through which a cooling fluid can circulate.

[0034] To improve the cooling effect, a cooling gas can be circulated through the gap between the mirror unit and the cover, either alternatively or additionally. The volume flow of the cooling gas must be selected so that no back pressure is generated in the gap, which would negatively affect the mirror movement.

[0035] The scanner mirror can preferably comprise a mirror substrate made of a transparent material, in particular quartz glass. Residual transmission of laser radiation through the scanner mirror, which is unavoidable when a laser beam strikes the reflection surface, can thus be specifically directed toward the rear of the scanner mirror. Lateral heat dissipation toward the mirror mount and the drive unit can thus be prevented. The mirror substrate preferably has a thickness-to-diameter ratio of at most 1:10. This ensures the necessary rigidity of the scanner mirror. For example, the scanner mirror can have a diameter of 25 mm and a thickness of 2.5 mm.

[0036] The scanner mirror may further comprise an oxide interference coating.

[0037] The present invention according to the third aspect therefore also has significant advantages over the prior art with regard to cooling. The improved cooling reduces the susceptibility of the scanner unit to heating as the laser power increases. The scanner assembly with sealing element and cover can also have a bypass connection equipped with a particle filter to bridge the sealing element. The bypass connection can connect the drive chamber and the optics chamber on the other side of the sealing element. The bypass connection ensures pressure equalization between the working chamber and the optics chamber, thus reducing pressure-related resistance that would otherwise impede the movement of the mirror unit.

[0038] The scanner assembly (see third aspect of the invention) or the scanner unit without a diaphragm (see first aspect of the invention) can each be arranged suspended in the laser processing head. A suspended arrangement in this context describes an orientation of the scanner mirror downwards or in the direction of gravity. The suspended arrangement of the scanner assembly refers to a preferred working position of the laser processing head in which the laser beam is directed perpendicularly onto an object to be processed, in particular a metallic, plate-shaped, or tubular workpiece. With regard to particle sealing, the advantages of the present invention become particularly apparent when the scanner assembly is arranged suspended.

[0039] Examples of implementation

[0040] The following description of preferred embodiments, in conjunction with the drawings, serves to explain the invention in more detail.

[0041] They show:

[0042] Fig. 1 shows a laser cutting system for laser beam cutting in a schematic, perspective view;

[0043] Fig. 2 is a schematic representation of a laser cutting head according to the invention;

[0044] Fig. 3a is a sectional view of a scanner arrangement for a laser processing head according to the invention; Fig. 3b is an enlarged section of the illustration according to Figure 3a; and

[0045] Fig. 3c shows a further sectional view of the scanner arrangement according to Figure 3a.

[0046] Figure 1 shows a laser processing system in the form of a laser cutting system 10. The laser cutting system 10 comprises a laser beam source 12. The laser beam source 12 can be a CO2 laser, a solid-state laser, or a diode laser. Even if the present illustration shows a CO2 laser configuration in which the generated laser beam L is guided via deflection mirrors to the laser processing head—here, a laser cutting head 20—solid-state lasers, in particular disk or fiber lasers, can generally be preferred as beam sources. With solid-state lasers, the laser beam L is generally transported to the laser cutting head 20 via an optical fiber (not shown in Figure 1) and fed into the laser cutting head 20 via a connection socket.

[0047] The laser cutting system 10 further comprises a cutting gas supply 14, here in the form of a gas cylinder 14, via which a cutting gas, which generally contains nitrogen and / or oxygen, is transported via a line to the laser processing head 20 and, together with the laser beam L, is directed through a cutting nozzle at a predetermined pressure onto a workpiece 30 to be processed—here plate-shaped. The workpiece 30 is mounted on a workpiece support 20 for processing by the processing beam comprising laser beam L and cutting gas jet. By a relative movement between the workpiece 30 and the laser cutting head 20, the workpiece 30, which is preferably a metallic workpiece 30, is locally melted, and the resulting melt is expelled downwards, creating a cutting gap 32 in the workpiece 30.The laser cutting system 10 further comprises a control device which is programmed to move the cutting head 20 relative to the workpiece 30 according to a cutting contour.

[0048] Figure 2 schematically shows a laser cutting head 20 according to the invention in which the optics cause a delta fold of the laser beam L. The laser beam L enters the laser cutting head 20 through an inlet opening 21. Preferably, the inlet opening 21 can be designed as a connection socket for a fiber optic cable, via which the laser beam L is transported from a laser beam source to the laser cutting head 20. The diverging laser beam L emerging from the fiber optic cable is collimated by means of a collimation device, here a collimation lens 22. The collimated laser beam L is then deflected by a deflection unit, here a deflection mirror 23, such that it is directed at a predefined angle of incidence onto the scanner mirror 242 of a scanner arrangement 24, which is arranged suspended in the laser cutting head 20.The scanner arrangement 24 is configured to tilt the scanner mirror 242 about at least two axes of rotation in a comparatively small movement interval of up to ±2°, preferably up to ±0.3°, relative to a rest position or zero position of the scanner mirror 242.

[0049] The scanner arrangement 24 comprises an aperture 246 arranged in front of the scanner mirror 242. The laser beam L is deflected at the scanner mirror 242 by an angle α, which is preferably at most 60°, preferably at most 45°, and even more preferably at most 30°, and directed onto an exit opening 28 of the laser cutting head 20. On the way to the exit opening 28, which is preferably designed as a cutting nozzle, the laser beam L can first be expanded by an expansion device, here a negative lens 25, before being focused by a focusing device, here a focusing lens 26, toward the exit opening 28, via which it leaves the laser cutting head 20 together with a cutting gas jet (not shown) and is directed as a cutting beam onto a workpiece to be machined.

[0050] Through the controlled tilting of the scanner mirror 242, the laser beam L can be deflected very quickly within a predetermined movement interval within the exit opening 28, i.e., within the cutting nozzle, in a plane (here, the xy plane) transverse to the exit direction of the laser beam 242. The primary feed movement of the cutting beam during a cutting process can thus be superimposed by a comparatively small and rapid secondary movement of the laser beam L. This superimposed secondary pendulum movement or scanner movement of the laser beam L can be used to specifically influence the cutting process, for example, to widen the cutting gap in certain places or to change the cutting front inclination.

[0051] The connector socket at the entrance opening 21 of the laser cutting head 20 and / or the collimation lens 22 can be displaceable transversely to the beam path, i.e., laterally (here in the X direction). In addition, the deflection mirror 23 can have an inclination adjustment. This allows the laser beam L to be precisely aligned to a center of the scanner mirror 242. The negative lens 25 can be mounted displaceably along the beam path (here in the Z direction). By displacing the negative lens 25 in the Z direction, the focus position Lf of the laser beam L can be easily changed.

[0052] A horizontal arrangement of the inlet opening 21 as shown in Figure 2 is generally less susceptible to contamination than a vertical arrangement. Furthermore, due to the horizontal arrangement of the inlet opening 21, the collimating lens 22 is oriented vertically within the laser cutting head 20. A vertically arranged collimating lens 22 is also generally less susceptible to contamination, since the lens surface does not form a receptacle for particles in the optical space.

[0053] Figures 3a to 3c each show a sectional view of a scanner assembly 24 for a laser processing head according to the invention. The scanner assembly 24 comprises a mirror unit with a scanner mirror 242 and a mirror mount 243. The scanner mirror 242 has a cylindrical shape and, together with the mirror mount 243, is tiltably mounted in the scanner assembly 24. For example, the mirror mount 243 can be suspended in a frame 241 of the scanner assembly 24 at four points evenly distributed around its circumference by a solid-state joint. A drive unit 244 (indicated here by dashed lines) is configured to tilt the mirror mount 243, together with the scanner mirror 242, at high frequency about at least two rotational axes, preferably oriented perpendicular to one another.An annular plastic sealing element 243 is arranged between the frame 241, which can be fastened in a laser processing head 20, and the mirror unit 242. The sealing element 243 has a wave-shaped cross-section with a shaft 2456. Along its inner circumference, the sealing element 245 has a trapezoidal first thickening 2452, which is mounted in a likewise trapezoidal circumferential groove 2432 on the outer circumference of the mirror mount 243. Along its outer circumference, the sealing element 245 has a second thickening 2454, which is clamped in a circumferential recess 2412 of the frame 241 by means of a clamping ring 2414. The frame 241, the mirror unit 242, and (optionally) the sealing element 243 together form a scanner unit of the scanner arrangement 24.

[0054] The scanner arrangement 24 further comprises a diaphragm 246 with a diaphragm opening 2462. The diaphragm opening 2462 is surrounded by a funnel-shaped inner wall of the diaphragm 246, wherein the inner wall preferably has a maximum inclination angle of 30°, preferably 22.5°, more preferably 15°, relative to a surface normal of the scanner mirror 242 (in a rest position of the scanner mirror 242). The smallest opening diameter of the diaphragm opening 2462 is smaller than the aperture of the scanner mirror 242. In this way, the mirror mount 243 can be effectively shielded by the diaphragm 246 and protected from unwanted irradiation. The diaphragm 246 has a circumferential collar 2464 that extends close to the scanner mirror 242 and serves both as a particle barrier and as radiation protection.

[0055] On the side of the mirror unit 242 opposite the aperture 246, the cover 248 is arranged and fastened to the frame 241. Together with the frame 241, the mirror unit 242, and the sealing element 243, the cover 248 defines an actuator or drive chamber of the scanner arrangement. The cover 248 is designed here as a heat sink 248 and protrudes closely to the rear side of the scanner mirror 242. The aperture 246 and the heat sink 248 are each spaced apart from the scanner mirror 242 and the mirror mount 243 by a narrow gap to ensure their freedom of movement during controlled tilting. At the same time, the distances between the aperture 246 and the heat sink 248 and the scanner mirror 242 and the mirror mount 243 are kept as small as possible to ensure efficient heat dissipation.For example, the movements of the scanner mirror 242 during operation of the scanner assembly 24 can result in a displacement of the outer diameter of the mirror mount 243 of ±80 pm. This relative movement must be taken into account accordingly.

[0056] The design of the gap dimensions and also the dimensioning of the sealing element 245 must be taken into account in this application.

[0057] To improve heat dissipation from the scanner mirror 242 and / or the mirror mount 243, the aperture 246 and the heat sink 248 are preferably made of steel or another material with good thermal conductivity properties. Furthermore, the aperture 246 and the heat sink 248 can be actively cooled. The latter promotes the establishment of natural convection in the small air gap. For this purpose, they can each have one or more cooling channels 247. The cooling channels 247 can be connected to a cooling circuit via cooling fluid connections 249, in which a liquid or gaseous cooling fluid flows through the cooling channels, thereby dissipating heat from the aperture 246 and / or the heat sink 248.

[0058] List of reference symbols

[0059] 10 laser cutting machines

[0060] 12 Laser beam source

[0061] 14 Cutting gas supply

[0062] 16 Workpiece support

[0063] 20 laser cutting heads

[0064] 21 Entrance opening

[0065] 22 Collimating lens

[0066] 23 deflecting mirrors

[0067] 24 scanner arrangement

[0068] 241 frames

[0069] 2412 recess

[0070] 2414 clamping ring

[0071] 242 scanner mirrors

[0072] 243 Mirror frame

[0073] 2432 groove

[0074] 244 drive unit

[0075] 245 Sealing element

[0076] 2452 First thickening

[0077] 2454 Second thickening

[0078] 2456 Wave

[0079] 246 aperture

[0080] 2462 aperture

[0081] 2464 Round collar

[0082] 247 Cooling channel

[0083] 248 Cover

[0084] 249 Cooling fluid connection

[0085] 25 negative lens

[0086] 26 Focusing lens

[0087] 28 Exit opening

[0088] 30 Workpiece 32 Cutting gap

[0089] L laser beam

[0090] Lf Focus of the laser beam a Deflection angle at the scanner mirror

Claims

Patent claims Laser processing head (20) with a scanner unit, the scanner unit comprising: a mirror unit with a scanner mirror (242), wherein the mirror unit has a circumferential groove (2432); a frame (241) that can be fastened in the laser processing head (20), wherein the mirror unit is movably mounted in the frame (241); and an annular, elastic sealing element (245), wherein the sealing element (245) is fastened to the frame (241) at its outer circumference and engages with the circumferential groove (2432) at its inner circumference. Laser processing head (20) according to claim 1, wherein the sealing element (245) has a wave-shaped cross-section.Laser processing head (20) according to claim 1 or 2, wherein the circumferential groove (2432) has a cross-section that tapers towards the groove base, and wherein the sealing element (245) has a first thickened portion (2452) along its inner circumference, which is complementary in shape to the groove (2432). Laser processing head (20) according to claim 3, wherein the first thickened portion (2452) along the inner circumference of the sealing element (245) has a greater width than the groove (2432) in the groove base. Laser processing head (20) according to one of the preceding claims, wherein an inner circumference of the sealing element (245) in a relaxed state. State is smaller, in particular by at least 2% and / or by at most 20% smaller, than a circumference of the groove (2432) in the groove base. Laser processing head (20) according to one of the preceding claims, wherein the sealing element (245) is adhesively bonded to the mirror unit along its inner circumference within the groove (2432). Laser processing head (20) according to one of the preceding claims, wherein the sealing element (245) has a second thickened portion (2454) along its outer circumference, and wherein the frame (241) forms a clamping connection with the second thickened portion (2454) of the sealing element (245) along its inner circumference.Sealing element (245) for a scanner unit of a laser processing head (20) according to one of the preceding claims, the sealing element (245) comprising: an annular base body made of an elastic material, wherein the base body has a first, in particular trapezoidal thickening (2452) along its inner circumference and a second, in particular circular thickening (2454) along its outer circumference. Sealing element (245) according to claim 8, wherein the base body has a wave-shaped cross-section in a relaxed state of the sealing element (245). Sealing element (245) according to claim 8 or 9, wherein the base body is made of silicone. Sealing element (245) according to one of claims 8 to 10, wherein a thickness of the base body is at least 0.2 mm and / or at most 0.8 mm, preferably approximately 0.6 mm. A laser processing head (20) with a scanner arrangement (24), the scanner arrangement (24) comprising: a scanner unit with a mirror unit comprising a scanner mirror (242) and a frame (241), wherein the mirror unit is movably mounted in the frame (241); and a diaphragm (246) with a diaphragm opening (2462), wherein the diaphragm (246) is fastened to the frame (241), wherein a smallest diameter of the diaphragm opening (2462) is smaller than an aperture of the scanner mirror (242), and wherein the diaphragm (246) and the mirror unit are spaced apart from one another in the axial direction by a gap, wherein a minimum gap width is at most 2 mm, preferably at most 1 mm, in particular approximately 0.8 mm. The laser processing head (20) according to claim 12, wherein the scanner unit corresponds to the scanner unit of a laser processing head (20) according to one of claims 1 to 7.Laser processing head (20) according to claim 12 or 13, further comprising: a cover (248) which can be fastened to a side of the frame (241) opposite the aperture (246) and which covers an opening formed by the frame (241) of the scanner unit, wherein the cover (248) preferably projects into the frame (241) at the rear side of the mirror unit, such that a gap formed between the cover (248) and the rear side of the mirror unit has a smallest gap width of at most 3 mm, preferably at most 0.7 mm. Laser processing head (20) according to one of claims 1 to 7 or one of claims 12 to 14, wherein the scanner unit or the scanner arrangement (24) is arranged in a suspended manner in the laser processing head (20).

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