Method and apparatus for lithography-based generative manufacturing of three-dimensional parts

Abstract

In a method for lithography-based generative manufacturing of three-dimensional components, in which at least one beam emitted by an electromagnetic radiation source (2) is focused in succession onto a focal point within a material by means of an illumination device (3), whereby volume elements (13) of the material located at the focal point are each solidified by means of multiphoton absorption, the focal point is displaced in a z direction, wherein the z direction corresponds to the direction of incidence of the at least one beam into the material, wherein the displacement of the focal point in the z direction is carried out by means of at least one acousto-optic deflector (6) arranged in the beam path, in which an acoustic wave is generated, the frequency of which is periodically modulated.

Description

Technical Field

[0001] The present invention relates to a method for photolithography-based generative manufacturing of three-dimensional parts, wherein at least one beam emitted by an electromagnetic radiation source is sequentially focused onto a focal point within a material by means of an irradiation device, thereby solidifying the volume elements of the material located at the focal point by means of multiphoton absorption.

[0002] The present invention also relates to an apparatus for photolithography-based generative manufacturing of three-dimensional parts. Background Technology

[0003] For example, a method for constructing molded articles is known from DE 10111422 A1, in which a photosensitive material is cured by means of multiphoton absorption. For this purpose, a focused laser beam is incident on a pool of the photosensitive material, wherein irradiation conditions for triggering the multiphoton absorption process for curing are satisfied only in the vicinity of the focal point, such that the focal point of the beam is guided within the pool volume to the point to be cured according to the geometry of the molded article to be produced.

[0004] In this case, the volume elements of the material are solidified at their respective focal points, with adjacent volume elements adhering to each other, and the molded article is constructed through the sequential solidification of adjacent volume elements. When constructing the molded article, actions are taken layer by layer; that is, the volume elements of the first layer are solidified before the volume elements of the next layer are solidified.

[0005] An irradiation apparatus for a multiphoton absorption method includes an optical system for focusing a laser beam and a deflection device for deflecting the laser beam. In this case, the deflection device is configured to sequentially focus the beam onto focal points within the material, said focal points being located in the same plane extending perpendicular to the direction of incidence of the beam into the material. In the x,y,z coordinate system, this plane is also referred to as the x,y plane. Layers of the molded article are formed by solidified volume elements resulting from beam deflection in the x,y plane.

[0006] To construct the next layer, the relative position of the irradiation device to the component is changed in the z-direction, which corresponds to the direction of at least one beam incident into the material and extends perpendicular to the x,y plane. Due to the adjustment of the irradiation device relative to the component, which is in most cases electrically, the focal point of the irradiation device is shifted to a new x,y plane that is spaced apart from the previous x,y plane in the z-direction by the desired layer thickness.

[0007] The described operating mode results in the solidified volumetric elements being generated only at pre-defined locations within a 3D mesh. However, this leads to a stepped construction at curved surfaces of the part, analogous to the pixelated representation of curved lines on a screen. The structured resolution at the part's surface in this case depends on the size of the solidified volumetric elements and the layer thickness. To improve the structured resolution, the layer thickness can be reduced; however, this results in a significant increase in the construction process duration because the number of layers must be increased.

[0008] Various suggestions have been given to adapt the dimensions of cured volumetric elements to the desired surface shape in the edge regions of a component, minimizing the deviation between the actual and desired surfaces. For example, DE 1020171140241A1 discloses a method in which the exposure dose for producing volumetric elements adjacent to the surface is varied according to a defined pattern. This results in volumetric elements written into the edge segments having different extents, and thus contributes to the desired surface structuring. However, a disadvantage of such a method is that the energy injected into the material when increasing the exposure dose can cause thermal damage to the material and may lead to blistering. Furthermore, the range of adjustment is very limited in this method. The maximum change in the size of the volumetric elements is less than 20% of the initial size.

[0009] Documents US 2003 / 013047 A1 and US 2014 / 029081 A1 constitute general prior art with respect to the subject matter of this invention. Summary of the Invention

[0010] Therefore, the object of the present invention is to further develop a method and apparatus for photolithography-based generative manufacturing of three-dimensional parts, namely, to construct curved and inclined surfaces of parts with high shape accuracy and to avoid the disadvantages mentioned above.

[0011] To address this task, the present invention, in the case of a method of the type mentioned at the beginning, specifies that the focal point is shifted in the z-direction, wherein the z-direction corresponds to the injection direction of at least one beam into the material, wherein the focal point is shifted in the z-direction by means of at least one acousto-optic diverter arranged in the optical path, in which sound waves are generated, the frequency of which is periodically modulated.

[0012] By arranging at least one acousto-optic diverter in the optical path of the beam emitted from the radiation source, the focal point can be continuously and rapidly shifted in the z-direction. This allows for free selection of the position of volumetric elements in the z-direction, and thus also allows the volumetric elements to be arranged outside the positions defined by the aforementioned grid, so as to achieve optimal fit with the respective surface shapes to be realized. In this case, the shift of the focal point in the z-direction does not require mechanical adjustment of the irradiation device relative to the component, and is therefore independent of the transformation from the first layer to the next. In particular, the shift of the focal point in the z-direction is achieved solely by the action of the aforementioned acousto-optic diverter without any moving parts.

[0013] An acousto-optic diverter is an optical device that influences the frequency and propagation direction or intensity of incident light. To this end, an optical grid is generated in a transparent solid using sound waves, at which the beam is diffracted and simultaneously shifted in its frequency. This produces beam deflection, where the deflection angle depends on the relative wavelengths of the light wave and the ultrasound wave in the transparent solid.

[0014] The periodic variation in the frequency of sound waves generated in a transparent solid creates a so-called "cylindrical lens effect," which focuses the incident beam in the same way as a cylindrical lens. Targeted control of the periodic frequency modulation allows for alteration of the focal length of the cylindrical lens and thus the divergence of the beam exiting the acousto-optic diverter. The beam with this set divergence is guided through the imaging unit of the irradiation device, where it is focused into the material by means of an objective lens. In this case, the focal point of the beam introduced into the material changes in the z-direction according to the divergence.

[0015] In this case, a preferred construction scheme specifies that the frequency modulation of the sound wave has a constant sound wave frequency gradient. This contributes to the so-called "cylindrical lens effect." However, if the sound wave frequency changes non-linearly, wavefront error is formed.

[0016] Preferably, it is further specified that the focus point is shifted by changing the frequency gradient of the (constant) sound wave. This change in the sound wave frequency gradient can be achieved, for example, by varying the bandwidth of the frequency modulation while keeping the period duration of the periodic modulation constant. Alternatively, the bandwidth can be kept constant, and the change in the sound wave frequency gradient can be caused by changing the period duration.

[0017] The fundamental frequency of the sound wave is preferably 50 MHz or higher, especially >100 MHz, particularly 100-150 MHz, in the case of a transparent solid made of, for example, TeO2. For example, the fundamental frequency is modulated by at least ±10%, preferably ±20-30%. In the case of a fundamental frequency of, for example, 110 MHz, the fundamental frequency is periodically modulated by ±25 MHz, i.e., the bandwidth of the frequency modulation is 50 MHz, and thus the frequency of the sound wave is periodically modulated between 85 MHz and 135 MHz. As already mentioned, the change in the frequency gradient of the sound wave determines the focal length of the cylindrical lens, wherein the modulation frequency is preferably at least 100 kHz, particularly 0.1-10 MHz.

[0018] Preferably, at least two acousto-optic diverters are used sequentially in the optical path, wherein the at least two acousto-optic diverters preferably have beam deflection directions that extend substantially perpendicular to each other or the same beam deflection orientation. The combination of two acousto-optic diverters, preferably arranged directly perpendicularly in succession, eliminates astigmatism that would otherwise occur with a single diverter. When two acousto-optic diverters are arranged in a plane, the possible displacement paths (Verstellweg) of the focal point in the z-direction are doubled. According to another preferred embodiment, four acousto-optic diverters can be arranged sequentially, wherein the first two diverters constitute a first pair and the subsequent two diverters constitute a second pair. In this case, the diverters within a pair are constructed with the same beam deflection orientation, and the diverters of the first pair have beam deflection directions that extend perpendicularly to the diverters of the second pair.

[0019] As is known per se, the focal point is preferably also transferred in the xy-plane extending laterally in the z-direction, wherein the transfer in the xy-plane is carried out by means of a deflection unit other than at least one acousto-optic diverter. In this case, the deflection unit is advantageously arranged in the optical path between at least one acousto-optic diverter and the imaging unit. For example, the deflection unit can be configured as a galvanometer scanner. For two-dimensional beam deflection, either the mirrors can be deflected in both directions, or two orthogonal rotatable mirrors can be placed close to each other, through which the beam is reflected. The two mirrors can be driven separately by a galvanometer drive or an electric motor.

[0020] The component is preferably constructed layer by layer using layers extending in the xy plane, wherein the transition from one layer to the next involves changing the relative position of the irradiation device with respect to the component in the z-direction. Coarse adjustment of the focal point in the z-direction is achieved by mechanically adjusting the relative position of the irradiation device with respect to the component, i.e., transitioning from one layer to the next. To establish intermediate levels in the z-direction, i.e., to finely position the focal point in the z-direction, the position of the focal point is changed by means of an acousto-optic diverter.

[0021] In this case, it is preferable to take action such that the focal point is shifted in the z-direction within the layer thickness by means of an acousto-optic diverter. Alternatively, multiple layers of volumetric elements arranged in a stacked manner in the z-direction can be produced within the layer without the need for mechanical adjustment of the relative position of the irradiation device to the component.

[0022] According to a preferred application of the invention, the focal point is shifted in the z-direction by means of an acousto-optic diverter to construct a curved outer contour of the component. Alternatively or supplementarily, it may be possible to shift the focal point in the z-direction by means of an acousto-optic diverter to construct an outer contour of the component that extends obliquely relative to the x,y plane. In this case, the shift of the focal point in the z-direction can follow the surface shape by positioning the focal point in the edge region of the component at a distance from the surface of the component to be produced, the distance corresponding to the distance from the envisioned midpoint of the volume element to be cured to the outer surface of the volume element.

[0023] A preferred treatment method is derived when the material is present on a material carrier, such as in a trough, and is irradiated from below through the material carrier, which allows at least partial penetration of radiation. In this case, the construction platform can be positioned at a distance from the material carrier, and the component can be constructed on the construction platform by curing the material located between the construction platform and the material carrier. However, alternatively, it is also possible to irradiate the material from above.

[0024] Multiphoton absorption offers the advantage of providing extremely high structural resolution for structuring suitable materials, enabling the realization of volumetric elements with minimum structural dimensions as small as 50 nm × 50 nm × 50 nm. However, due to the small focal volume, this method suffers from very low throughput, for example, for a 1 mm... 3 The total volume must be exposed more than 10. 9 This results in very long build times, which is a major reason for the low industrial use of multiphoton absorption methods.

[0025] In order to increase component throughput without sacrificing the possibility of high structural resolution, a preferred further development of the invention specifies that the volume of the focal point is changed at least once during component construction, such that the component is constructed from solidified volume elements of different volumes.

[0026] Due to the variable volume of the focal point, high resolution is possible (with a small focal point volume). Simultaneously, high write speeds (in milliseconds) can be achieved (with a large focal point volume). 3(Measured in units of / h). By changing the focal volume, high resolution can be combined with high throughput (Durchsatz). Here, for example, variations in focal volume can be used such that a large focal volume is used inside the part to be constructed to increase throughput, while a smaller focal volume is applied at the surface of the part to construct a part surface with high resolution. Because the volume of material cured during exposure increases, increasing the focal volume enables higher structuring throughput. To maintain high resolution at high throughput, a small focal volume can be used for finer structures and surfaces, while a larger focal volume is used for rougher structures and / or to fill internal spaces. Methods and apparatus for changing the focal volume are described in WO 2018 / 006108 A1.

[0027] Within the scope of this invention, if layers located inside the component are constructed with high-thickness and therefore large-volume volume elements, and edge regions are created by small-volume volume elements, and the positions of the volume elements are additionally adapted individually along the z-direction in the edge regions to obtain high structural resolution at the surface, the construction time can be significantly reduced.

[0028] In a preferred method, the focal volume is changed such that the volume ratio between the maximum focal volume and the minimum focal volume during component manufacturing is at least 2, preferably at least 5.

[0029] The principle of multiphoton absorption is used within the scope of this invention to initiate photochemical processes in a pool of photosensitive materials. Multiphoton absorption methods, for example, also include methods involving two-photon absorption. Due to the photochemical reaction, the material changes to at least one other state, where photopolymerization typically occurs. The principle of multiphoton absorption is based on the fact that the aforementioned photochemical processes occur only in those regions where the presence of an optical path provides sufficient photon density for multiphoton absorption. The highest photon density occurs at the focal point of the optical imaging system, such that multiphoton absorption occurs with sufficient probability only at the focal point. Outside the focal point, the photon density is low, making the probability of multiphoton absorption outside the focal point too small to cause irreversible changes in the material through photochemical reactions. Electromagnetic radiation can pass through the material with maximum unimpeded flow at the wavelength used, and the interaction between the photosensitive material and the electromagnetic radiation occurs only at the focal point. The principle of multiphoton absorption is described, for example, in Zipfel et al.'s "Nonlinear magic: multiphoton microscopy in the biosciences", NATUREBIOTECHNOLOGY VOLUME 21 NUMBER 11 NOVEMBER 2003.

[0030] The preferred source for electromagnetic radiation is a collimated laser beam. Not only can the laser emit one or more fixed or variable wavelengths, but it is also particularly important that the laser be a continuous or pulsed laser with pulse lengths in the nanosecond, picosecond, or femtosecond range. Pulsed femtosecond lasers offer the advantage of requiring lower average power for multiphoton absorption.

[0031] Photosensitive materials are understood to be any material that can flow or remain solid under constructed conditions, transitioning to a second state through multiphoton absorption (e.g., via polymerization) in a focal point volume. Here, the material change must be confined to the focal point volume and its immediate environment. Changes in material properties can be persistent and can occur, for example, in a change from liquid to solid, but can also be merely temporary. Furthermore, persistent changes can be reversible or irreversible. Changes in material properties do not necessarily have to be a complete transition from one state to another, but can also exist as a mixture of both states.

[0032] The power of electromagnetic radiation and the exposure duration affect the quality of the resulting part. The volume of the focal point can be varied within a narrow range by adapting the radiation power and / or exposure duration. Excessively high radiation power results in additional processing that can potentially damage the part. If the radiation power is too low, no lasting changes in material properties occur. Therefore, for each photosensitive material, there are typical build process parameters associated with good part properties.

[0033] Preferably, the change in the volume of the focal point is carried out in at least one, preferably two, and especially three spatial directions that are perpendicular to each other.

[0034] According to a second aspect of the invention, an apparatus is provided for photolithography-based generative manufacturing of three-dimensional parts, particularly for performing a method according to a first aspect of the invention. The apparatus includes a material carrier for a curable material and an irradiation device, the irradiation device being operable to selectively irradiate the curable material with at least one beam, wherein the irradiation device includes an optical deflection unit to sequentially focus at least one beam onto a focal point within the material, whereby volume elements of the material located at the focal point can be cured by means of multiphoton absorption. The irradiation device is characterized by including at least one acousto-optic diverter arranged in the optical path of the beam, the acousto-optic diverter being configured to shift the focal point in the z-direction, wherein the z-direction corresponds to the direction of incidence of at least one beam into the material.

[0035] The control device for at least one acoustic-optical diverter preferably includes a frequency generator configured to periodically modulate an ultrasonic frequency.

[0036] In this case, it is preferably specified that the frequency generator is configured to change the frequency gradient of the sound wave.

[0037] As already mentioned in connection with the method according to the invention, it is advantageous if at least two acousto-optic diverters are arranged successively in the optical path, wherein the at least two acousto-optic diverters preferably have beam deflection directions that extend substantially perpendicular to each other or the same beam deflection orientation.

[0038] Furthermore, the deflection unit is preferably configured to shift the focal point in the xy plane that extends laterally to the z-direction.

[0039] In particular, the irradiation device can be configured to build components layer by layer using layers extending in the xy plane, wherein transitioning from one layer to the next includes changing the relative position of the irradiation device with respect to the component in the z direction.

[0040] The irradiation device is preferably configured such that the shift of the focal point in the z-direction is carried out within the layer thickness by means of an acousto-optic diverter.

[0041] Furthermore, it can be specified that the material exists on a material carrier, such as in a trough, and is irradiated from below through the material carrier, which is at least partially permeable to radiation.

[0042] In this case, the construction platform is preferably positioned at a certain distance from the material carrier, and the component is constructed on the construction platform by solidifying the volume elements located between the construction platform and the material carrier.

[0043] Here, it is advantageous if the volume of the focal point is changed at least once during the construction of the component, so that the component is constructed from solidified volume elements of different volumes. Attached Figure Description

[0044] The invention will now be described in more detail with reference to embodiments schematically illustrated in the accompanying drawings. In the accompanying drawings, Figure 1 A schematic diagram of the device according to the present invention is shown. Figure 2 Showing according to Figure 1 The modified implementation of the device, and Figure 3 A schematic diagram showing the arrangement of volume elements in the edge region of a component. Detailed Implementation

[0045] exist Figure 1In the diagram, a substrate or carrier is indicated by 1, on which components should be constructed. The substrate is arranged in a material tank (not shown), which is filled with a photopolymerizable material. A laser beam emitted from a radiation source 2 is sequentially focused into the photopolymerizable material at a focal point by means of an irradiation device 3, thereby solidifying the volume elements of the material at the focal point by means of multiphoton absorption. For this purpose, the irradiation device includes an imaging unit, which includes an objective lens 4 that introduces the laser beam into the material within the writing region.

[0046] The laser beam first enters the pulse compressor 5 from the radiation source 2 and is then conducted through at least one acousto-optic diverter module 6, whose two acousto-optic diverters divide the beam into a zero-order beam and a first-order beam. The zero-order beam is collected in the beam trap 7. In this case, the acousto-optic diverter module 6 comprises two sequentially arranged acousto-optic diverters whose beam deflection directions extend perpendicularly to each other. Given the deflected first-order beam, the acousto-optic diverter module 6 functions as cylindrical lenses with adjustable focal lengths, such that the first-order beam has adjustable divergence. The first-order beam is then guided into the deflection unit 9 via a relay lens 8 and a deflecting mirror 15, where the beam is reflected sequentially at two mirrors 10. The mirrors 10 are driven in a manner rotatable about rotation axes extending orthogonally to each other, such that the beam can be deflected not only in the x-axis but also in the y-axis. The two mirrors 10 can be driven by a galvanometer drive or an electric motor, respectively. The beam emitted from the deflection unit 9 preferably enters the objective lens through a relay lens system (not shown), which, as already mentioned, focuses the beam onto the photopolymerizable material.

[0047] To construct the component layer by layer, volumetric elements are solidified in the material, one layer after another. To construct the first layer, a laser beam is successively focused onto a focal point within the material, which is located in the focal plane of the objective lens 4. In this case, the beam is deflected in the x,y plane by means of a deflection unit 9, wherein the writing area is limited by the objective lens 4. To transition to the next plane, the objective lens 4, fixed to the carrier 11, is shifted relative to the substrate 1 in the z-direction by a layer distance corresponding to the layer thickness. Alternatively, the substrate 1 can also be shifted relative to the fixed objective lens 4.

[0048] If the part to be produced is larger than the writing area of ​​the objective lens 4 in the x and / or y directions, then the partial structure of the part is constructed side by side (so-called splicing). For this purpose, the substrate 1 is arranged on the stage 12, which can be shifted relative to the irradiation device 3 in the x and / or y directions.

[0049] In addition, a control device 12 is provided, which controls at least one sound and light diverter 6, a deflection device 9, a carrier 11, and a platform 12.

[0050] The acoustic-optical diverter 6 creates a cylindrical lens effect, which depends on the frequency gradient of the frequency-modulated acoustic wave. In this case, the cylindrical lens... The equivalent focal length can be calculated as follows:

[0051]

[0052] in It is the speed of sound propagation in a crystal. It is the wavelength of the laser beam and This is the acoustic frequency gradient in the crystal. With a laser wavelength of 780 nm and a bandwidth of ±25 MHz (e.g., starting from a fundamental excitation frequency of 110 MHz) passing through TeO2 with a propagation speed of 4200 m / s, the focal length of the acousto-optic cylindrical lens is determined to be 90 mm. With an objective lens 4 having a focal length of 9 mm and an expansion of 20 × 10⁻⁶, the new focal length of the overall system is thus obtained.

[0053] ,

[0054] This corresponds to a displacement in the z-direction of ±90 μm, depending on the sign of the gradient, given the parameters mentioned above. The z-position of the volume element can be linearly and continuously adjusted by changing the acoustic frequency gradient.

[0055] According to the invention, the described possibilities for continuously shifting the focal point in the z-direction can be fully utilized to optimally approximate inclined or curved surfaces, as is the case in Figure 3 As illustrated in the diagram. Figure 3 In the diagram, each volume element is labeled 13, and the curved surfaces of the component are labeled 14. It can be seen that the z-position of the volume element 13 is made to track the surface shape, wherein the dimensions of each volume element 13 can remain the same.

[0056] exist Figure 2 According to Figure 1 The modified implementation of the device, wherein the sound and light steering module 6 and Figure 1 It has two acousto-optic diverters with relay lenses arranged between them, so as to ensure that the focal points at the input and output of the acousto-optic diverter module 6 are arranged on the same line.

Claims

1. A method for photolithography-based generative fabrication of three-dimensional parts, wherein at least one beam emitted from an electromagnetic radiation source (2) is sequentially focused onto a focal point within a material by means of an irradiation device (3), whereby volume elements (13) of the material located at the focal point are solidified by means of multiphoton absorption, characterized in that, The focal point is shifted in the z-direction, wherein the z-direction corresponds to the direction of incidence of the at least one beam into the material, wherein the shift of the focal point in the z-direction is performed by means of at least one acousto-optic diverter (6) arranged in the optical path, wherein sound waves are generated in the acousto-optic diverter, the frequency of which is periodically modulated, wherein the focal point is shifted in the z-direction by means of the acousto-optic diverter (6) in order to construct a curved outer contour of the component or an outer contour that extends obliquely relative to the x,y plane.

2. The method according to claim 1, characterized in that, The focal point is shifted by changing the frequency gradient of the frequency-modulated sound wave.

3. The method according to claim 1 or 2, characterized in that, At least two acoustic-optical diverters (6) are used sequentially in the optical path.

4. The method according to claim 3, characterized in that, The at least two acoustic-optical diverters (6) have beam deflection directions that are substantially perpendicular to each other or the same beam deflection orientation.

5. The method according to claim 1 or 2, characterized in that, The focal point is shifted in the xy plane that extends laterally to the z direction, wherein the shift in the xy plane is performed by means of a deflection unit (9) that is different from the at least one acousto-optical steering device (6).

6. The method according to claim 1 or 2, characterized in that, The component is constructed layer by layer using layers extending in the xy plane, wherein the transformation from one layer to the next includes changing the relative position of the irradiation device (3) with respect to the component in the z direction.

7. The method according to claim 6, characterized in that, The focal point is shifted in the z-direction within the layer thickness by means of the acousto-optic diverter (6).

8. The method according to claim 1 or 2, characterized in that, The dimensions of the volume elements (13) that constitute the outer contour are chosen to be the same.

9. An apparatus for photolithography-based generative fabrication of three-dimensional parts, for performing the method according to any one of claims 1 to 8, the apparatus comprising a material carrier (1) for a curable material and an irradiation device (3), the irradiation device being operable to selectively irradiate the curable material with at least one beam, wherein the irradiation device (3) includes an optical deflection unit (9) for sequentially focusing at least one beam onto a focal point within the material, whereby volume elements (13) of the material located at the focal point can be cured by means of multiphoton absorption, characterized in that, The irradiation device (3) includes at least one acousto-optic diverter (6) arranged in the optical path of the beam, the acousto-optic diverter being configured to shift the focal point in the z-direction, wherein the z-direction corresponds to the injection direction of the at least one beam into the material.

10. The device according to claim 9, characterized in that, The at least one acoustic-optical diverter (6) includes a frequency generator configured to periodically modulate ultrasonic frequencies.

11. The device according to claim 9 or 10, characterized in that, The frequency generator is configured to change the frequency gradient of the sound wave.

12. The device according to claim 9 or 10, characterized in that, At least two acoustic-optical diverters (6) are arranged successively in the optical path.

13. The device according to claim 12, characterized in that, The at least two acoustic-optical diverters (6) have beam deflection directions that are substantially perpendicular to each other or the same beam deflection orientation.

14. The device according to claim 9 or 10, characterized in that, The deflection unit (9) is configured to shift the focal point in the xy plane that extends laterally to the z direction.

15. The device according to claim 9 or 10, characterized in that, The irradiation device (3) is configured to construct the component layer by layer using layers extending in the xy plane, wherein the transformation from one layer to the next includes changing the relative position of the irradiation device (3) with respect to the component in the z direction.

16. The device according to claim 9 or 10, characterized in that, The irradiation device (3) is configured such that the focal point is shifted in the z-direction within the layer thickness by means of the acousto-optic diverter (6).

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