Device and method for laser material processing and / or laser modification

Abstract

The invention relates to a laser material processing device comprising a laser resonator, a scanning head and a lens changing device. The invention further relates to a method for modifying the working distance during laser material processing.

Description

[0001] DEVICE AND METHOD FOR LASER MATERIAL PROCESSING AND / OR MODIFICATION

[0002] The invention relates to a laser material processing device comprising a laser resonator, a scanning head, and a lens changing device. The invention further relates to a method for changing the working distance during laser material processing.

[0003] State of the art

[0004] Laser material processing generally has the particular advantage of being able to be performed dry and without the use of chemicals. Furthermore, it is generally a non-contact and / or force-free processing method that also causes no material damage. Laser material processing has low operating costs and is therefore highly cost-effective.

[0005] In the laser material processing apparatus that performs processing such as cutting or welding for a workpiece, the processing is preferably performed under an optimal laser processing condition so that results of high processing accuracy and processing quality are obtained at a high speed.

[0006] Several factors determine the desirability of a laser processing system. These include accuracy, quality, usability, flexibility, and throughput. Throughput is a very important consideration due to its direct impact on the cost of processing on a per-part basis. System throughput is a function of several factors, including the material removal rate and the workpiece and laser beam positioning speed. To change the working distance, particularly when processing components with complex geometries, lenses (F-theta lenses, telecentric lenses, flat-top lenses, or top-hat lenses) are currently used, which are positioned between the component and the scan head.

[0007] The F-theta lens—also known as a scan lens or flat-field lens—is a lens system used in many scanning applications. It is inserted into the beam path after the scan head and performs various functions. Firstly, the lens focuses the laser beam on the focal point; secondly, it ensures that this focal point is always in the lens's working plane during scanning. Furthermore, the position in the working plane approximately follows the F-theta condition, meaning that the scan length (image height) is roughly proportional to the set scan angle. An F-theta lens also serves to keep the focal plane of a focused laser beam constant during movement, for example, in a marking field. Using a normal lens, the focus would shift from the focal plane as soon as the laser beam leaves the center of the marking field, as the distance from the lens to the marking field then increases.

[0008] The key quality features of good F-theta lenses are low field curvature, a large field of view, and good and consistent focus across the entire image field. An important criterion here is whether the focus is diffraction-limited. These F-theta lenses feature multiple elements, which can lead to various problems. Examples include internal and external ghosting.

[0009] Internal ghosts

[0010] Ghosts or back reflections are caused by the reflection of light from a lens or protective glass surface behind it. Internal ghosts are characterized by a focus position on lens elements within the lens.

[0011] Anti-reflective coatings optimize the transition from the optically thinner medium of air to the optically denser medium of glass, so that surface losses are only approximately 0.2% instead of the original 4%. Despite the low absorption losses, the use of lasers often exceeds the damage threshold and thus causes damage to the affected lens element.

[0012] Most lenses are constructed from two to six elements. The solution is to design the lens in such a way that no back reflections occur near the lenses. Such "ghost-free" lenses are highly recommended for high- and medium-power lasers (kilowatt range) and short-pulse lasers. Short-pulse-compatible, ghost-free lenses are made of uncemented glass with low temperature coefficients (primarily fused silica).

[0013] External ghosts

[0014] Ghosts are reflections from lens surfaces or the protective glass. High-power lasers can damage optical elements at the focus of the reflections. Internal reflections occur on lens surfaces within the lens. These lenses are generally unsuitable for high-power lasers.

[0015] In contrast, external ghosts are located on the object side, outside the lens. In this case, high-power lasers can be used safely. However, the distance between the lens and the rest of the setup must be carefully chosen. If the focus of a ghost is on an upstream optical element (typically the mirror of the scan head), damage can occur there.

[0016] Therefore, F-Theta lenses are complex and costly to manufacture, have a relatively high weight and, especially in the UV or UVC range, a high purchase price.

[0017] Task It is therefore the object of the present invention to provide a method for changing the working distance in laser material processing, which can be carried out reliably and cost-effectively using simple means.

[0018] It is also an object of the present invention to provide a laser material processing device with which a working distance can be reliably and cost-effectively adjusted and changed.

[0019] The working distance of a laser system is usually defined as the physical distance from the last optical element (usually a focusing lens) to the object or surface onto which the laser is focused. For certain applications, e.g. medical lasers, the working distance should be as short as possible, e.g. in cutting applications (e.g. cutting glass), while for other applications the working distance range should be as large as possible, e.g. for annealing marks on metal or color changes on plastics or paints. The working distance A is the distance between the central axis of the entrance aperture and the working plane. A is also determined by the focal length and installation position of the F-theta lens (if present). In pre-focus systems, the distance A is determined by the dynamic focusing unit in the zero position.

[0020] This object is achieved by means of the laser material processing device according to the invention for processing components with complex component geometries. Advantageous embodiments of the invention are also set forth in the subclaims.

[0021] The laser material processing device according to the invention for processing components with complex component geometries comprises a laser resonator, a scanning head for deflecting the laser radiation and a lens changing device.

[0022] Laser resonators or beam sources within the meaning of this patent include any type of (beam) source, such as X-ray devices, EUV beam sources, etc., that generate radiation in a wavelength range between 0.01 nm and 400 nm. Furthermore, the term "laser resonator" within the meaning of this document also includes a light guide and / or a coupling window for coupling radiation in a wavelength range of 0.01 nm to 400 nm into the laser material processing device, wherein the beam source is arranged externally of the laser material processing device and is therefore not part of the laser material processing device.

[0023] A scan head, as defined in this document, is any device for deflecting a laser beam that is intended and suitable for guiding a laser beam to various positions on a component to be processed for the purpose of processing. These include, for example, (laser) beam deflection units, for example in the form of acousto-optical deflectors, a polygon mirror, or a scan head (galvano scanner).

[0024] For the purposes of this document, the term laser material processing encompasses any processing of a material in which the structure of the material is altered by the action of a laser. This also includes a structural change in the processed material that renders a flying object incapable of flight. A laser material processing device, for the purposes of this document, is therefore any device that can perform laser material processing using laser radiation.

[0025] A component with a complex component geometry within the meaning of the invention is a component that has a plurality of surfaces. The surface of a component can be composed of flat or curved surface segments and / or have flat and / or circular or spherical interfaces that are at any angle to one another. Furthermore, the component can have undercuts and / or cavities. In particular, such a component requires different working distances for the laser radiation of the laser resonator. The working distance of the laser material processing device is usually defined as the physical distance from the last optical element (here: the scan head) to the object or surface onto which the laser radiation is focused.

[0026] A scan head, as defined in this document, is any deflection unit capable of deflecting the laser beam in one or more directions and / or directing it toward another part of the component to be processed. Examples include a scan head, polygon scanner, acousto-optical deflectors, and / or one or more galvanometer scanners. A galvanometer scanner is a highly dynamic electro-optical component that uses a rotatable, low-inertia mirror to position a laser beam with high accuracy and repeatability. Typically, two galvanometer scanners are used to deflect the laser beam in two directions using these two scanners.

[0027] According to the invention, the lens changing device is preferably arranged between the laser resonator and the scanning head. Alternatively, the lens changing device can also be arranged behind the scanning head.

[0028] In an alternative embodiment of the invention, the use of an F-theta lens, which is arranged between the scan head and the component and typically comprises a plurality of lenses, is eliminated. The laser material processing device is therefore inexpensive, small, lightweight, and handy, yet the processing of a component is still precise and fast.

[0029] Laser material processing can be performed on numerous different workpieces using different lasers, which perform a variety of processes. Examples of laser material processing include laser sintering, stereolithography, laser bending and laser-assisted bending, laser cutting and drilling, laser ablation, laser trimming, laser welding, laser cladding and brazing, laser marking, laser spraying and evaporation, laser polishing, laser (micro)structuring, and annealing.

[0030] In an optional embodiment of the invention, the laser resonator comprises nonlinear optical medium FV for frequency doubling or multiplication.

[0031] In one development of the invention, the laser material processing device is suitable for processing a component by structurally changing the material of the component. This includes material processing types such as marking, laser welding, inscription, engraving and cutting. In an optional embodiment, the laser material processing device is suitable for abrasively processing a component. In a further embodiment of the invention, the laser resonator generates laser resonator radiation with a wavelength of 0.01 nm to 400 nm, preferably 10 nm to 315 nm, particularly preferably 100 nm to 280 nm and especially preferably 200 nm to 280 nm. The laser medium of the laser resonator comprises all known laser types, such as solid-state lasers, gas lasers (also excimer lasers, metal vapor lasers), dye lasers or free-electron lasers. The laser resonator can be operated either in pulsed or continuous wave mode.This enables a wide range of laser material processing types.

[0032] In an advantageous embodiment of the invention, the lens changing device is suitable for changing the maximum focal length of the laser material processing device in a range of 1,000 mm to 100,000 mm.

[0033] In an advantageous embodiment of the invention, the lens changing device is suitable for changing the minimum focal length of the laser material processing device in a range of 5 mm to 50 mm.

[0034] In an advantageous embodiment of the invention, the lens changing device is suitable for changing the focal length of the laser material processing device in a range of 5 mm to 100,000 mm, preferably in a range of 20 mm to 10,000 mm and particularly preferably in a range of 50 mm to 1,000 mm.

[0035] In a further embodiment of the invention, the lens changing device comprises one or more lenses. In particular, the lenses optionally have different focal lengths. This allows for different working distances.

[0036] In a further development of the invention, the working distances can be varied within a range of 1 mm to 15 mm, 5 mm to 500 mm, 10 mm to 1000 mm, 15 mm to 750 mm, 25 mm to 600 mm, 35 mm to 450 mm, 50 mm to 800 mm, 75 mm to 700 mm, or 100 mm to 1200 mm, and / or beyond that, up to 5 km. Lenses, as defined in this document, are all optical elements that can be used to change the focal length of an optical system. Thus, the term "lens" as defined in this document also includes aspheres, which enable diffraction-limited focusing without the need for a complete lens system, creating a focusing option that is very small and lightweight. Furthermore, other lenses are also included, such as multifocal lenses or small lens systems, such as achromats consisting of only two lenses or preferably achromats with an air gap, etc., as well as so-called microlenses.Mirrors are also included to adjust the laser power. Furthermore, so-called holographic optical elements (HOEs) are also included, although these optical elements can be of various types (lenses, mirrors, directional diffusers, etc.). Using HOEs, for example, a "continuous" focus progression can be created (different focus distances can be changed, whereby the change does not occur abruptly, but rather as a smooth transition). Furthermore, using HOEs also allows individual "beam geometries" to be projected onto the workpiece. The normally round or nearly round laser beam is then, for example, square, or the laser beam takes on a more complex geometry, which can even consist of several individual structures or even result in a photorealistic representation.

[0037] In a further embodiment of the invention, one or more lenses of the lens changing device can be movably positioned relative to the beam path. In a further embodiment of the invention, one or more lenses of the lens changing device can be positioned in the beam path. By arranging different lenses at different times in the beam path, different working distances are possible.

[0038] In a further embodiment of the invention, one or more lenses are movable by a rotational and / or translational movement. The lenses are arranged on or at the lens changing device such that a lens and / or a combination of several lenses (lens system) can be arranged in the beam path by a rotational and / or translational movement. In a further embodiment of the invention, the lens changing device and laser resonator and / or scan head are arranged so as to be movable relative to one another. In a further aspect of the invention, the lens changing device and laser resonator and / or scan head are movable relative to one another by a translational movement. In a further embodiment of the invention, the translational movement occurs parallel to the beam path. In this case, either the laser resonator or the lens changing device can be movable.The only relevant aspect of the invention is that the laser resonator and lens changing device can move relative to each other parallel to the beam path. By moving the laser resonator and / or laser beam and lens changing device relative to the beam path, the focal point on the component is adjusted in such a way that a small change in the working distance An (<50 mm) is achieved.

[0039] The object is also achieved by means of the inventive method for varying the working distance during laser material processing. Advantageous embodiments of the invention are also set forth in the subclaims.

[0040] The inventive method for varying the working distance during laser material processing comprises five process steps: In the first process step, laser radiation is generated in a laser resonator. The laser medium of the laser resonator includes all known laser types, such as solid-state lasers, gas lasers (including excimer lasers and metal vapor lasers), dye lasers, and free-electron lasers. The laser resonator can be operated in either pulsed or continuous wave mode. This enables a wide range of laser material processing methods.

[0041] In the second process step, laser radiation is coupled out of the laser resonator. In the third process step, laser radiation generated from the laser resonator radiation is deflected onto the component to be processed, with the first laser radiation having a first working distance.

[0042] In the fourth method step, the first working distance is changed to a second working distance. The change in the working distance is achieved by exchanging a first lens arranged in the beam path with a second lens using a lens changing device arranged between the laser resonator and the scan head. The lens changing device has two or more lenses that can be arranged alternately or in combination in the beam path by the lens changing device, such that one lens and / or a combination of several lenses (lens system) is arranged in the beam path at any one time.

[0043] In the fifth method step, the laser radiation is deflected at the second working distance onto the component to be processed, with the first and second working distances differing by at least 50 mm. In a preferred embodiment, the first and second working distances differ by at least 100 mm, more preferably by at least 200 mm, and especially preferably by at least 1000 mm.

[0044] The laser beam is deflected by a scanning head, which is optionally a galvanometer scanner. The lens changing device is located between the laser resonator and the scanning head. This eliminates the need for an F-theta lens, which is located between the scanning head and the component and typically consists of multiple lenses. The laser material processing device is therefore inexpensive, small, lightweight, and portable, yet still allows for precise and fast processing of a component.

[0045] In a further embodiment of the invention, the laser resonator generates laser resonator radiation with a wavelength of 0.01 nm to 400 nm, preferably 10 nm to 315 nm, more preferably 100 nm to 280 nm, and especially preferably 200 nm to 280 nm. The laser medium of the laser resonator encompasses all known laser types, such as solid-state lasers, gas lasers (including excimer lasers and metal vapor lasers), dye lasers, or free-electron lasers. The laser resonator can be operated in either pulsed or continuous wave mode. This enables a wide range of laser material processing methods.

[0046] In a further embodiment of the invention, the focal length of the laser resonator radiation is changed by the lens changing device to generate the first laser radiation. A first lens with a first focal length can be positioned in the beam path by means of the lens changing device. In a further embodiment of the invention, the lens changing device positions a first lens in the beam path to change the laser resonator radiation with the laser resonator focal length to the first laser radiation with the first focal length. The lens changing device has two or more lenses that can be arranged in the beam path by the lens changing device such that one lens and / or a combination of several lenses (lens system) is arranged in the beam path at any one time.

[0047] In a further embodiment of the invention, the lens changing device positions a second lens in the beam path to change the laser resonator radiation with the laser resonator focal length and / or the first laser radiation with the first focal length to the second laser radiation with the second focal length. The second focal length is different from the first focal length, so the working distances of the first and second lenses are also different from each other.

[0048] In a further development of the invention, the working distance is varied within a range of 5 mm to 500 mm, 10 mm to 1000 mm, 15 mm to 750 mm, 25 mm to 600 mm, 35 mm to 450 mm, 50 mm to 800 mm, 75 mm to 700 mm, or 100 mm to 1200 mm. The focus can thus be changed almost continuously from just a few mm to 100 mm, several meters, or even greater distances.

[0049] In a further development of the invention, the first lens is removed from the beam path when the second lens is positioned in the beam path. Therefore, only one lens is positioned in the beam path at a time.

[0050] In a further embodiment of the invention, positioning is achieved by a rotational and / or translational movement. The lenses are arranged on or at the lens changing device such that a lens can be arranged in the beam path by a rotational and / or translational movement. In a further configuration of the invention, the lens changing device comprises one or more lenses arranged so as to be movable with respect to the beam path. Optionally, all lenses and / or combinations of lenses arranged on the lens changing device have different focal lengths. This makes it possible to achieve a multitude of different working distances. In addition to the different focal lengths, lenses can alternatively and / or additionally have other properties that differ, such as lenses provided with special nanostructures.

[0051] In a further aspect of the invention, the lens changing device performs a translational movement relative to the position of the laser resonator and / or the scan head. In a further development of the invention, the translational movement occurs parallel to the beam path. Either the laser resonator or the lens changing device can be movable. The only relevant aspect of the invention is that the laser resonator and the lens changing device can perform a relative movement parallel to the beam path. By moving the laser resonator and the lens changing device relative to the beam path, the focal point on the component is adjusted in such a way that a slight change in the working distance An is achieved.

[0052] In a further embodiment of the invention, the first and / or second laser beam is deflected by a scanning head. Optionally, the scanning head is a galvanometer scanner. A galvanometer scanner is a highly dynamic electro-optical component that uses a rotatable, low-inertia mirror to position a laser beam with high accuracy and repeatability.

[0053] Embodiments of the laser material processing device according to the invention and of the method according to the invention for changing the working distance are shown in a simplified schematic form in the drawings and are explained in more detail in the following description.

[0054] They show:

[0055] Fig. 1 : Laser material processing device

[0056] Fig. 2: Laser material processing device, lens changing device with four lenses Fig. 3: Laser material processing device, laser drilling of the component

[0057] Fig. 4 a: Laser material processing device, laser resonator arranged in a translationally movable manner

[0058] Fig. 4 b: Laser material processing device, lens changing device arranged in a translationally movable manner

[0059] Fig. 4 c Laser material processing device, lens changing device arranged in a translationally movable manner with additional optics in front of the lens changing device

[0060] Fig. 4 d Laser material processing device, lens changing device arranged in a translationally movable manner with additional optics behind the lens changing device

[0061] Fig. 5 Laser material processing device with two lens changing devices arranged parallel to each other

[0062] Fig. 6 Laser material processing device with two lens changing devices arranged non-parallel to each other

[0063] Fig. 7 a: Embodiment of a lens changing device

[0064] Fig. 7 b: Embodiment of a lens changing device

[0065] Fig. 7 c: Embodiment of a lens changing device

[0066] Fig. 1 shows an embodiment of a laser material processing device LMB. The laser material processing device LMB has the laser resonator LR. The laser resonator LR has a laser crystal LK, which in this embodiment is an Nd:-doped crystal. In principle, however, other laser media are also possible, e.g. gas lasers, dye lasers, diode lasers, excimer lasers, etc. The laser resonator LR additionally has a non-linear optical medium FV for frequency doubling, as well as two end mirrors, one end mirror being partially transparent for coupling out the laser resonator radiation LSR. The laser resonator LR itself is diode-pumped. Due to the frequency doubling by the non-linear optical medium FV, the laser resonator LR emits laser resonator radiation LSR with a wavelength of 532 nm and a laser resonator focal length.The laser resonator LR generates laser resonator radiation LSR with a wavelength of 0.01 nm to 400 nm, preferably 10 nm to 315 nm, more preferably 100 nm to 280 nm, and especially preferably 200 nm to 280 nm. In all embodiments presented here, the type of material processing of the component is abrasive and / or leads to a structural change in the material. This includes material processing methods such as marking (e.g., annealing or creating color changes), laser welding, marking, engraving, and cutting.

[0067] The laser resonator radiation LSR is directed along a beam path to the component BT with a complex geometry, whereby the laser resonator radiation LSR is deflected by the movable scan head SK for processing the component BT. The scan head SK is a

[0068] Galvanometer scanner. A galvanometer scanner is a highly dynamic electro-optical device that uses a low-inertia, rotating mirror to position a laser beam with high accuracy and repeatability.

[0069] The lens changing device LWV is arranged between the laser resonator LR and the scan head SK. In this embodiment, it has only one lens L1 with a fixed focal length. As a result, the laser material processing device LMB has only one working distance A1, but at least two different working distances A1, A2 would be necessary to efficiently process the component BT.

[0070] Fig. 2 shows an embodiment of a laser material processing device LMB according to the invention. The laser material processing device LMB corresponds to the one already described in the previous embodiment (see Fig. 1), except that the lens changing device LWV is arranged between the laser resonator LR and the scan head SK. In this embodiment, the lens changing device LWV has four lenses L1, L2, L3, and L4 with mutually different focal lengths BWn. Lens L1 has the focal length, lens L2 the focal length L2, lens L3 the focal length L3, and lens L4 the focal length L4. In addition to the different focal lengths, lenses can alternatively and / or additionally have other properties that differ, such as lenses provided with special nanostructures.

[0071] To change the working distance A1, A2, a laser resonator radiation LSR is generated in the laser resonator LR and coupled out. At a first point in time, the first lens L1 is arranged in the beam path and generates a first laser radiation LS1 with a first focal length, which is directed by the scan head SK onto the component BT at a first working distance A1. At a second point in time, the lens changing device LWV is moved such that the lenses Ln fixedly arranged thereon move perpendicular to the beam path of the laser resonator radiation LSR. As a result, the first lens L1 is removed from the beam path and the second lens L2 is positioned in the beam path. Using this second lens L2, the laser material processing device LMB generates a second laser radiation LS2 with a second focal length, which is directed by the scan head SK onto the component BT at a second working distance A2.

[0072] At a third time, the lens changing device LWV is moved such that the lenses Ln fixedly mounted thereon move perpendicular to the beam path of the laser resonator radiation LSR. This removes the second lens L2 from the beam path and positions the third lens L3 into the beam path. Using this third lens L3, the laser material processing device LMB generates a third laser beam LS3 with a third focal length BW3, which is directed by the scan head SK onto the component BT at a third working distance A3.

[0073] At a fourth time, the lens changing device LWV is moved such that the lenses Ln fixedly mounted thereon move perpendicular to the beam path of the laser resonator radiation LSR. This removes the third lens L3 from the beam path and positions the fourth lens L4 into the beam path. Using this fourth lens L4, the laser material processing device LMB generates a fourth laser beam LS4 with a fourth focal length BW4, which is directed by the scan head SK onto the component BT at a fourth working distance A4.

[0074] Fig. 3 shows a further embodiment of a laser material processing device LMB according to the invention. The laser material processing device LMB corresponds to the one described in the previous embodiment (see Fig. 2); in this embodiment, the component BT is processed using a laser drilling process. The bore to be created is arranged parallel to the beam path of the laser material processing device LMB and requires a plurality of working distances A1, A2, which are realized using the lens changing device LWV. The working distances A1, A2 are changed using the method described in Fig. 2.

[0075] Fig. 4 shows an embodiment of a laser material processing device LMB according to the invention. The laser material processing device LMB corresponds to that described in the previous embodiment (see Fig. 2). In this embodiment, the laser resonator LR and the lens changing device LWV are arranged so as to be movable relative to one another parallel to the beam path (Figs. 4a and 4b). Either the laser resonator LR can be movable (Fig. 4a) or the lens changing device LWV can be movable (Fig. 4b). The only thing relevant to the invention is that the laser resonator LR and the lens changing device LWV can execute a relative movement to one another parallel to the beam path. The working distances A1, A2 are changed using the method described in Fig. 2. In addition, during the processing of the component BT, with the laser resonator LR activated, a relative translational movement of the laser resonator LR and / or the lens changing device LWV is executed.By moving the laser resonator LR and / or lens changing device LWV relative to the beam path, the focal point on the component BT is adjusted in such a way that an additional change in the working distance A1, A2 is achieved. This movement can also be used to refocus or fine-tune the focus.

[0076] Alternatively, a further additional optics Lx can be arranged adjacent to the lens changing device LWV and movable with respect to the distance thereto, which is suitable for performing a relative movement to each other parallel to the beam path (cf. Fig. 4c and 4d). This additional optics can, for example, be a further lens, a further lens system and / or a further optics suitable for changing the focal point of the laser beam. The additional optics Lx can be arranged between the laser resonator LR and the lens changing device LWV or between the lens changing device LWV and the scan head SK. The working distances A1, A2 are changed using the method described in Fig. 2; in addition, a relative translational movement of the additional optics Lx is carried out during the processing of the component BT with the laser resonator LR activated.The relative movement of the additional optics Lx parallel to the beam path adjusts the focal point on the component BT in such a way that an additional change in the working distance A1, A2 is achieved. This movement can also be used to refocus or fine-tune the focus.

[0077] The relative movement of the laser resonator LR, the lens changing device LWV and / or the additional optics Lx described in Fig. 4a to d is preferably carried out in an advantageous embodiment (because it is fast and precise down to the nanometer range) by means of a piezo drive. Piezo drives can move quickly and have a repeatability / positioning accuracy in the nanometer range. This is important for the precise and repeatable positioning of the respective optical elements and thus also for the correspondingly precise and fast (micro)material processing. When performing a laser drilling, e.g. in glass several cm thick, the movement of the laser resonator LR, the lens changing device LWV and / or the additional optics Lx or in conjunction with the respective optical element of the lens changing device LWV, e.g.L1 = 4c or 4d)] the focus can be adjusted by the relative movement, so that lasering can also be carried out over longer distances in the focus without changing the lens currently in use in the lens changing device LWV.

[0078] Fig. 5 shows a further embodiment of a laser material processing device LMB according to the invention. The laser material processing device LMB corresponds to that described in the previous embodiment (see Fig. 4d). In addition to a first lens changing device LWV1 with four lenses L1.1, L2.1, L3.1, L4.1, a second lens changing device LWV2 with four lenses L1.2, L2.2, L3.2, L4.2 is arranged between the first lens changing device LWV and the scan head SK. Both lens changing devices LWV1, LWV2 are movable. Both lens changing devices LWV1, LWV2 are arranged so as to be movable relative to one another relative to the laser resonator LR, parallel to the beam path. With the help of the two separately movable lens changing devices LWV1, LWV2, the lenses L1.1, L2.1, L3.1, L4.1, L1.2, L2.2, L3.2, L4.2 of the respective lens changing device LWV1, LWV2 can be positioned in the beam path.This allows a variety of lenses L1.1, L2.1, L3.1, L4.1, L1.2, L2.2, L3.2, L4.2 to be combined to set different working distances A1, A2. During processing of the component BT, with the laser resonator LR activated, a relative translational movement of the lens changing devices LWV1, LWV2 is carried out. By a relative movement of the lens changing devices LWV1, LWV2 parallel to the beam path, the focal point on the component BT is adjusted in such a way that an additional change in the working distance A1, A2 is achieved. This movement can also be used to refocus or fine-tune the focus.

[0079] Furthermore, in this exemplary embodiment, a further additional optics Lx is arranged adjacent to the lens changing device LWV2 and movable parallel to the beam path. This additional optics can, for example, be a further lens, a further lens system and / or a further optics such as a mirror that is suitable for changing the focal point of the laser beam. The additional optics Lx can be arranged between the laser resonator LR and the first lens changing device LWV1, between the two lens changing devices LW1, LW2 or between the second lens changing device LWV2 and the scan head SK. Alternatively, multiple additional optics can also be used.

[0080] Fig. 6 shows an embodiment with a similar structure to Fig. 5. The key difference here is that the lenses L1.2, L2.2, L3.2, L4.2 of the second lens changing device LWV2 are designed as mirrors, which additionally deflect the laser beam LS. Coated mirrors have a higher damage threshold against high-energy radiation than conventional or coated lenses. This results in a longer service life.

[0081] In an alternative embodiment of the invention, lenses or mirrors have a continuously changing refractive index—similar to progressive lenses. This allows the focus to be continuously shifted by moving a lens changing device (LWV).

[0082] The relative movement of the laser resonator LR, the lens changing device LWV and / or the additional optics Lx described in Figs. 4a to d, 5 and 6 is preferably carried out in an advantageous embodiment (because it is fast and precise down to the nanometer range) by means of a piezo drive. Piezo drives can move quickly and have a repeatability / positioning accuracy in the nanometer range. This is important for the precise and repeatable positioning of the respective optical elements and thus also for the correspondingly precise and fast (micro)material processing. When performing a laser drilling, e.g. in glass several cm thick, the movement of the laser resonator LR, the lens changing device LWV and / or the additional optics Lx or in conjunction with the respective optical element of the lens changing device LWV, e.g.L1 = 4c or 4d)] the focus can be adjusted by relative movement, allowing lasering to be performed over longer distances in focus without changing the lens currently in use in the LWV lens changing device. It is advantageous to drill from bottom to top.

[0083] Fig. 7 shows embodiments of lens changing devices LWV. The figures show the lens changing devices LWV arranged parallel to the beam path. Each lens changing device LWV has six lenses L1, L2, L3, L4, L5, L6, which each have different focal lengths. According to the invention, the number of lenses L1, L2, L3, L4, L5, L6 arranged in the lens changing device LWV is not limited, thus any number of different working distances can be realized. The respective lenses L1, L2, L3, L4, L5, L6 are arranged on a carrier element TE lens changing device LWV. The laser material processing device LMB according to the invention can therefore be used for components BT with different complex geometries. The carrier element serves to hold the various lenses and / or to couple the lenses to a motor or actuator, via which the movement is carried out.

[0084] Fig. 7 a shows an advantageous variant of a lens changing device LWV with six lenses L1, L2, L3, L4, L5, L6, which are arranged coaxially on a carrier element TE of the lens changing device LWV. To change the working distance A1, A2, the lens changing device LWV performs a rotational movement about the central axis of the lens changing device LWV such that one of the six lenses L1, L2, L3, L4, L5, L6 is arranged in the beam path at a time. Fig. 7 b shows a lens changing device LWV with six lenses L1, L2, L3, L4, L5, L6, which are arranged side by side on a carrier element TE of the lens changing device LWV. To change the working distance A1, A2, the lens changing device LWV is moved translationally perpendicular to the beam path in such a way that at any one time one of the six lenses L1, L2, L3, L4, L5, L6 is arranged in the beam path.

[0085] Fig. 7 c shows a lens changing device LWV with six lenses L1, L2, L3, L4, L5, L6, which are also arranged next to one another on a carrier element TE of the lens changing device LWV. In this exemplary embodiment, the lenses L1, L2, L3, L4, L5, L6 are not circular as in all the previous exemplary embodiments (see Fig. 1 to Fig. 7 b), but have straight side edges with circular sections at the top and bottom. As a result of this advantageous embodiment of the lenses L1, L2, L3, L4, L5, L6, a larger number of lenses L1, L2, L3, L4, L5, L6 can be arranged on the lens changing device LWV per unit length than with a circular design of the lenses L1, L2, L3, L4, L5, L6. In addition, faster lens changes are possible and, due to the lower weight, less powerful actuators can be used for lens changes.To change the working distance A1, A2, the lens changing device LWV is moved translationally perpendicular to the beam path in such a way that at any one time one of the six lenses L1, L2, L3, L4, L5, L6 is arranged in the beam path.

[0086] In a further embodiment, the working distance of the laser material processing device is changed dynamically. The change in the working distance takes place in a time of less than 500 ms, preferably less than 200 ms, more preferably less than 100 ms, and especially preferably less than 10 ms. This is achieved because the laser beam does not have to be refocused when the lens changing device changes the lenses arranged in the beam path. This allows, for example, laser markings, microstructures, etc. to be applied to a three-dimensional body which, due to its geometric shape, has different working distances from the laser material processing device. In a further embodiment, different optics are selected and / or exchanged and / or combined or exchanged with one another, thus generating different arrangements (e.g. expansion factor in interaction with different focusing lenses).It should be emphasized here that, in addition to the dynamic focus (Lx in the drawings = for different (height) levels), several lens changing devices (LWV1, LWV2) are also used simultaneously to utilize a variety of combinations of optical elements (especially lenses). This allows a wide variety of optical effects to be achieved (e.g., by quickly changing the combination of different optical elements, an effect similar to that of a camera's zoom lens, different working areas (working area sizes / marking field sizes, if necessary with additional use of (laser) beam deflection units, for example in the form of acousto-optical deflectors, a polygon mirror, or a scan head, variable spot sizes).

[0087] Consequently, when using the lens changing device according to the invention, the use of F-theta lenses, telecentric lenses, or similar lenses can be eliminated altogether. Furthermore, the (complicated) changing of such lenses is also eliminated (e.g., when switching from micro material processing or marking to macro material processing or marking).

[0088] In a further embodiment of the invention, holes are first drilled and / or cut in glass at a distance of, for example, 50 mm - 150 mm. This requires even a small amount of focus adjustment (usually from bottom to top) (Lx in the drawings). The change in working distance due to focus adjustment is in a range from 1 mm to approx. 50 mm. In the next step, with an interruption in laser material processing of less than 5 seconds, a change is made to another focus plane, in this case to a working distance of 200 mm - 500 mm or even 1 m, in order to use the laser material processing device to insert a photo into a plastic material, for example, or to mark doors, house walls, etc. from several meters or even greater distances. Furthermore, for small marking orIn microstructuring areas, the use of a scanner is unnecessary: ​​Rapid movement of the lens(es) in the x and y directions deflects the focused laser beam past the lens. This makes the use of a scanner obsolete.

[0089] LIST OF REFERENCE SYMBOLS

[0090] LMB laser material processing device

[0091] L1, L2, L3, L4, L5, L6, lenses

[0092] L1.1, L1.2, L2.1, L2.2,

[0093] L3.1, L3.2, L4.1, L4.2

[0094] LWV, LWV1, LWV2 lens changing device

[0095] LR laser resonator

[0096] LK Laser Crystal

[0097] FV Nonlinear Optical Medium

[0098] LS laser radiation

[0099] SK scan head

[0100] A1,A2 working distance

[0101] BT component

[0102] LSR laser resonator radiation

[0103] Support element

[0104] Additional optics

Claims

PATENT CLAIMS 1. Laser material processing device (LMB) for processing components (BT) with complex component geometries with: • a laser resonator (LR) • a scanning head (SK) for deflecting the laser radiation • a lens changing device (LWV), wherein the lens changing device (LWV) is arranged between the laser resonator (LR) and the scanning head (SK), wherein the lens changing device is provided and suitable for changing the working distance (A1, A2) by at least 50 mm.

2. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to claim 1, characterized in that the laser material processing device (LMB) is suitable for processing a component (BT) by structurally changing the material of the component (BT).

3. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to claim 1 or 2, characterized in that the laser resonator (LR) generates laser resonator radiation (LSR) with a wavelength of 0.01 nm to 400 nm, preferably 10 nm to 315 nm, particularly preferably 100 nm to 280 nm and especially preferably 200 nm to 280 nm.

4. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to one or more of the preceding claims, characterized in that the lens changing device (LWV) is suitable for changing the focal length of the laser material processing device (LMB) in a range from 5 mm to 100,000 mm, preferably from 20 mm to 10,000 mm and particularly preferably from 50 mm to 1,000 mm.

5. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to one or more of the preceding claims, characterized in that the lens changing device (LWV) has one or more lenses (L1, L2, Ln).

6. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to claim 5, characterized in that one or more lenses (L1, L2, Ln) of the lens changing device (LWV) can be moved relative to the beam path.

7. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to claim 5 or 6, characterized in that one or more lenses (L1, L2, Ln) of the lens changing device (LWV) can be positioned in the beam path.

8. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to one or more of claims 5 to 7, characterized in that one or more lenses (L1, L2, Ln) are movable by a rotational and / or translational movement.

9. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to one or more of the preceding claims, characterized in that the lens changing device (LWV) and laser resonator (LR) and / or scanning head (SK) are arranged to be movable relative to one another.

10. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to claim 9, characterized in that the lens changing device (LWV) and the laser resonator (LR) and / or the scanning head (SK) are movable relative to one another by a translational movement.

11. Laser material processing device (LMB) for processing components (BT) with complex component geometry according to claim 10, characterized in that the translational movement takes place parallel to the beam path.

12. Method for changing the working distance (A1, A2) in laser material processing with the following process steps: • Generating laser resonator radiation (LSR) in a laser resonator (LR) • Coupling out a laser resonator radiation (LSR) from the laser resonator (LR) • Deflecting a laser radiation (LS) generated from the laser resonator radiation (LSR) onto the component to be processed (BT) with the aid of a scanning head (SK), wherein the first laser radiation (LS1) has a first working distance (A1), • Changing the first working distance (A1) of the laser radiation (LS) to a second working distance (A2) of the laser radiation (LS), wherein the change in the working distances (A1, A2) is effected by exchanging a first lens arranged in the beam path with a second lens by means of a lens changing device (LWV) arranged between the laser resonator (LR) and the scanning head (SK), wherein the change in the working distances (A1, A2) is at least 50 mm, • Deflecting the laser radiation (LS) with the second working distance (A2) onto the component to be processed.

13. Method for changing the working distance (A1, A2) in laser material processing according to claim 12, characterized in that the laser resonator (LR) generates a laser resonator radiation (LSR) with a wavelength of 100 nm to 400 nm, preferably 100 nm to 315 nm and particularly preferably 100 nm to 280 nm.

14. Method for changing the working distance (A1, A2) in laser material processing according to claim 12 or 13, characterized in that the focal length of the laser resonator radiation (LSR) is changed by the lens changing device (LWV) to generate the first laser radiation.

15. Method for changing the working distance (A1, A2) in laser material processing according to one or more of claims 12 to 14, characterized in that the lens changing device (LWV) positions a first lens (L1) in the beam path for changing laser resonator radiation (LSR) with the laser resonator focal length to the first laser radiation (LS1) with the first focal length.

16. Method for changing the working distance (A1, A2) in laser material processing according to one or more of claims 12 to 15, characterized in that the lens changing device (LWV) positions a second lens (L2) in the beam path for changing the laser resonator radiation (LSR) with the laser resonator focal length and / or the first laser radiation (LS1) with the first focal length to the second laser radiation (LS2) with the second focal length.

17. Method for changing the working distance (A1, A2) in laser material processing according to claim 16, characterized in that when positioning the second lens (L2) in the beam path, the first lens (L1) is removed from the beam path.

18. Method for changing the working distance (A1, A2) in laser material processing according to claim 17, characterized in that the positioning is carried out by a rotational and / or translational movement.

19. Method for changing the working distance (A1, A2) in laser material processing according to one or more of claims 12 to 18, characterized in that the lens changing device (LWV) comprises one or more lenses (L1, L2, Ln) arranged to be movable with respect to the beam path.

20. Method for changing the working distance (A1, A2) in laser material processing according to one or more of claims 12 to 19, characterized in that the lens changing device (LWV) carries out a translational movement in relation to the position of the laser resonator (LR) and / or the scanning head (SK).

21. Method for changing the working distance (A1, A2) in laser material processing according to claim 20, characterized in that the translational movement occurs parallel to the beam path.

22. Method for changing the working distance (A1 , A2) in the Laser material processing according to one or more of claims 12 to 21, characterized in that the deflection of the first (LS1) and / or second laser radiation (LS2) is carried out by a scanning head (SK).

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