Method and apparatus for lithography-based generative manufacturing of three-dimensional components - Patents.com

Abstract

In a method for lithography-based generative production of three-dimensional components, a beam is split by a beam splitter 4 into a number of beams which are focused by means of an optical imaging unit 10 to a focal point 21 in a material 2, which focal point 21 is displaced in the beam direction by means of a deflection unit arranged upstream of the optical imaging unit 10, whereby a volume element of the material is successively solidified at the focal point 21 of each beam by means of multiphoton absorption, and a number of acousto-optical modulator modules 11 corresponding to the number of beams is provided such that an acousto-optical modulator module 11 is arranged in the beam path of each beam.

Description

[Technical field]

[0001] The invention relates to a method for lithography-based generative production of three-dimensional components, in which a beam emitted by an electromagnetic radiation source is focused by means of an optical imaging unit to a focal point in a material, the focal point being displaced in the beam direction by means of a deflection unit arranged upstream of the optical imaging unit, and as a result of said focusing and displacement, volume elements of the material located at the focal point are each successively solidified by means of multiphoton absorption.

[0002] The invention further relates to an apparatus for lithography-based generative manufacturing of three-dimensional components. [Background technology]

[0003] A method for forming components, in which solidification of a photosensitive material is carried out by means of multiphoton absorption, is known, for example, from DE 10111422 A1. For this purpose, a focused laser beam is irradiated into a bath of photosensitive material, so that the irradiation conditions for the multiphoton absorption process inducing solidification are only fulfilled in the immediate vicinity of the focal point, whereby the focal point of the beam is directed to the point to be solidified in the bath volume according to the geometrical data of the component to be produced.

[0004] A volume element of material is solidified at each focal point, causing neighboring volume elements to adhere to one another, and the component is built up by successive solidification of neighboring volume elements. Components can be built up in layers, i.e., the volume elements of a first layer are solidified first, before the volume elements of the next layer are solidified.

[0005] The irradiation device for the multiphoton absorption method includes an optical system for focusing the laser beam and a deflection device for deflecting the laser beam. The deflection device is designed to continuously focus the beam to focal points in the material, preferably located in one and the same plane perpendicular to the direction of the beam incidence into the material. In the x, y, z coordinate system, this plane is further called the x, y plane. The solidified volume elements created by the beam deflection in the x, y plane form the layers of the component.

[0006] To build up the next layer, the relative position of the focusing optics relative to the component is changed in the z-direction, which corresponds to the direction of incidence of the at least one beam into the material and is perpendicular to the x,y-plane. By adjusting the focusing optics relative to the component, which is usually motorized, the focal point is shifted to a new x,y-plane, which is spaced from the previous x,y-plane in the z-direction by the desired layer thickness.

[0007] Structuring suitable materials using multiphoton absorption offers the advantage of extremely high structural resolution; volume elements with minimum structure sizes of up to 50 nm x 50 nm x 50 nm are achievable. However, due to the small focal point volume, the throughput of such methods is very low, since only a small focal point volume of, for example, 1 mm 3 For the volume of 10 9 This leads to very long build-up times, which is the main reason for the low industrial use of multiphoton absorption processes.

[0008] In order to increase the component throughput without losing the possibility of high structural resolution, it has already been proposed to vary the volume of the focal point by at least one degree during the construction of the component, so that the component is built up from solidified volume elements of different volumes. Due to the variable volume of the focal point, high resolution is possible (due to the small focal point volume). At the same time, high writing speeds (mm 3 A high resolution (measured in 1000 rpm / h) can be achieved (by a large focal point volume). Thus, by varying the focal point volume, a high resolution can be combined with a high throughput. A variation of the focal point volume can be used, for example, in such a way that a large focal point volume is used inside the component to be built up in order to increase the throughput, and a smaller focal point volume is used on the surface of the component in order to form a component surface with high resolution. By increasing the focal point volume, a higher structuring throughput is possible, because the volume of material solidified in one irradiation step is increased. To maintain a high resolution at a high throughput, a small focal point volume can be used for finer structures and surfaces, and a larger focal point volume can be used for coarse structures and / or to fill the interior space. A method and a device for varying the focal point volume are described in WO2018 / 006108A1. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] DE10111422A1 [Patent Document 2] WO2018 / 006108A1 [Non-patent literature]

[0010] [Non-Patent Document 1] Zipfel et al., "Nonlinear magic: multiphoton microscopy in the biosciences," NATURE BIOTECHNOLOGY, Vol. 21, No. 11, November 2003. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention is a method for reducing the writing speed (mm 3 The objective of the present invention is to further develop methods and devices for the lithography-based generative production of three-dimensional components in such a way that the throughput (measured in rpm / h) is even further increased. [Means for solving the problem]

[0012] To solve this problem, the invention provides that in a method of the type described above, the beam is split into a plurality of beams by a beam splitter, each of which is successively focused to a focal point in the material by means of a deflection unit and an optical imaging unit, and a number of acousto-optical modulator modules corresponding to the number of beams are provided such that an acousto-optical modulator module diffracting the beam is arranged in the beam path of each beam.

[0013] The invention thus allows parallel writing with multiple beams, whereby the writing speed is accordingly multiplied by the number of beams. The beam splitter is designed to split the beam into at least two beams. The beam splitter is preferably designed to split the beam into 2, 4, 8, 16, 32 or 64 beams. Any other number of beams, e.g. an odd number of beams, is even possible.

[0014] Since an acousto-optical modulator module is arranged in the beam path of each beam, preferably each beam can be influenced independently of the other beams, such that the position of the focal point of each beam can be adjusted independently of the focal points of the other beams, or the radiation intensity of each beam can be adjusted independently of the focal points of the other beams.

[0015] Depending on the configuration of the acousto-optical modulator modules, the focal point can be displaced in any spatial direction. Preferably, at least one of the acousto-optical modulator modules is controlled to shift the focal point of the associated beam in the z-direction, where the z-direction corresponds to the direction of incidence of the respective beam into the material.

[0016] Alternatively, or in addition, at least one of the acousto-optical modulator modules can be controlled to shift the focal point of the associated beam in the x and / or y directions, the x and y directions corresponding to two orthogonal directions in a plane perpendicular to the direction of incidence of the respective beam.

[0017] By arranging at least one acousto-optical modulator in the beam path of each beam, each focal point can be shifted continuously and at high speed in the x, y and / or z directions. This makes it possible to freely select the position of the volume elements and therefore even to arrange the volume elements outside the z position determined by the layer plane in order to achieve an optimal adaptation to the surface shape to be achieved in each case. The shifting of the focal point in the x, y and / or z direction does not require any mechanical adjustment of the optical imaging unit relative to the component and is therefore independent of the transition from the first layer to the next layer. In particular, the focal point can be shifted not by moving parts but exclusively due to the effect of the acousto-optical modulator module mentioned before.

[0018] An acousto-optical modulator is an optical component that affects the frequency and direction of propagation or intensity of incident light. For this purpose, an optical grating is created using acoustic waves in a transparent solid, in which a light beam is diffracted. This can be used in a structure known as an acousto-optical deflector to generate a beam deflection, whereby the deflection angle depends on the relative wavelengths of the light and sound waves in the transparent solid. The deflection angle can be adjusted by changing the acoustic wave frequency. This can be used for fine adjustment of the focal point in the x and / or y directions as explained above.

[0019] Displacement in the z-direction is achieved, for example, by generating in an acousto-optical deflector acoustic waves whose frequency is periodically modulated. By periodically varying the frequency of the acoustic waves generated in a transparent solid, a so-called "cylindrical lens effect" is formed in the acousto-optical deflector, which focuses the incident light beam in the same way as a cylindrical lens. By specific control of the periodic frequency modulation, it is possible to vary the focal length of the cylindrical lens and thus the divergence of the beam emerging from the acousto-optical deflector. The beam with the set divergence in this way is led through an imaging unit of an illumination device, where it is illuminated in a focused manner by means of a lens into the material. The focal point of the beam introduced into the material now varies in the z-direction as a function of the divergence.

[0020] The preferred design here specifies that the frequency modulation of the acoustic wave has a constant acoustic frequency gradient, which favors the creation of the so-called "cylindrical lens effect".

[0021] It is further provided that, preferably, the focal point is displaced by a change in the (constant) acoustic frequency slope of the frequency modulation. The change in the acoustic frequency slope can be achieved, for example, by changing the bandwidth of the periodic modulation while keeping the periodic period of the periodic modulation constant. Alternatively, the bandwidth can be kept constant and the change in the acoustic frequency slope can be caused by a change in the periodic period.

[0022] The fundamental frequency of the acoustic waves is preferably 50 MHz or more, in particular >100 MHz, especially 100-150 MHz, for example for a transparent solid made of TeO2. For example, the fundamental frequency is modulated by at least ±10%, preferably by ±20-30%. In the case of a fundamental frequency of for example 110 MHz, this fundamental frequency is periodically modulated by ±25 MHz, i.e. the bandwidth of the periodic modulation is 50 MHz and the frequency of the acoustic waves is therefore periodically modulated between 85 MHz and 135 MHz. As already mentioned, the change in the acoustic frequency gradient determines the focal length of the cylindrical lens, whereby the modulation frequency is preferably at least 100 kHz, in particular 0.1-10 MHz.

[0023] Furthermore, the acousto-optical modulator module may also be used to vary the intensity of the beam introduced into the material. The variation may even entail reducing the radiation intensity to 0 so that the beams emerging from the beam splitter can be individually switched on and off as required. To adjust the radiation intensity, the amplitude of the acoustic wave introduced into the acousto-optical modulator is varied.

[0024] An acousto-optical modulator module comprises at least one acousto-optical modulator, such as one, two or four acousto-optical modulators. In the case of at least two acousto-optical modulators, each modulator can be designed as a separate component through which the respective beams pass in series. Alternatively, at least two acousto-optical modulators can be functionally combined in a single modulator component (so-called multi-channel design) with a crystal into which the corresponding sound is input for each channel.

[0025] Preferably, at least two acousto-optical modulators are used in the acousto-optical modulator module, one arranged behind the other in the beam path, the at least two acousto-optical modulators preferably having a direction of beam deflection essentially perpendicular to each other or the same sense of beam deflection. The combination of two acousto-optical modulators, preferably arranged directly behind each other and perpendicular to each other, eliminates the astigmatism that would otherwise be produced by a single modulator. If two acousto-optical modulators are arranged in one plane, the possible adjustment paths of the focal point in the x and y directions are doubled. According to a further preferred embodiment, four acousto-optical modulators arranged in series can be provided, the first two of which form a first pair and the following two form a second pair. The modulators in a pair are each designed with the same sense of beam deflection, with the modulator of the first pair having a direction of beam deflection perpendicular to the modulator of the second pair.

[0026] While the shifting of the focal point by the acousto-optical modulator module is used for fine positioning of the focal point, e.g. for solidifying volume elements outside the normal grid points (so-called "gray-scale lithography"), the writing beam is moved throughout the entire writing area in the x and y directions by means of a deflection unit separate from the acousto-optical modulator module. In this context, a preferred design provides that the beam undergoes a joint deflection in the x and y directions by means of a deflection unit, in particular a galvanometer scanner, downstream in the beam path from the acousto-optical modulator module. The deflection unit is advantageously arranged in the beam path between the acousto-optical modulator module and the optical imaging unit. For two-dimensional beam deflection, a mirror can be deflected in two directions, or else two orthogonally rotatable mirrors can be placed close to each other, by which the beam is reflected. It is even possible to arrange a lens system, in particular a 4f arrangement, between the mirrors so that the axis of rotation of the first mirror is projected onto the second mirror, thereby avoiding geometric imaging errors. The two mirrors can each be driven by a galvanometer drive or an electric motor. In any case, it is essential that all the beams generated by the beam splitter and then passing through each acousto-optical modulator module are deflected with the aid of one and the same deflection unit and then focused into the material by one and the same optical imaging unit.

[0027] Preferably, the component is built up layer by layer, extending in the xy-plane, whereby the transition from one layer to the next entails changing the relative position of the optical imaging unit relative to the component in the z-direction. A mechanical adjustment of the relative position of the optical imaging unit relative to the component results in a coarse adjustment of the focal point in the z-direction, i.e., from one layer to the next. For adjustment of the intermediate stage in the z-direction, i.e., for fine positioning of the focal point in the z-direction, the position of the focal point is changed by means of the acousto-optical modulator module mentioned previously.

[0028] Preferably, the focal point can be shifted in the z-direction by means of an acousto-optical modulator module within the layer thickness of the layer. Several sublayers of volume elements arranged one above the other in the z-direction can be produced within one layer, moreover, without having to mechanically adjust the relative position of the optical imaging unit relative to the component.

[0029] According to a preferred application of the invention, at least one of the focal points is displaced in the z direction by means of the acousto-optical modulator module in order to form a curved outer contour of the component. Alternatively or additionally, at least one of the focal points can be displaced in the z direction by means of the acousto-optical modulator module in order to form an outer contour of the component that is inclined relative to the x,y plane. The displacement of at least one of the focal points in the z direction can follow the surface shape by defining a position of the focal point in an edge area of ​​the component at a distance from the surface of the component to be produced that corresponds to the distance of the imaginary center of the volume element to be solidified from the outer surface of the volume element.

[0030] According to a preferred method, the material is present on a material support, such as in a trough, and irradiation of the material is performed from below through the material support, which is transparent to the radiation in at least some areas. In this case, a build platform can be positioned at a distance from the material support, and the component can be built up on the build platform by solidifying the material located between the build platform and the material support. Alternatively, it is even possible to irradiate the material from above.

[0031] In the context of the present invention, the build time can be significantly reduced if layers located in the interior of the component are built up by volume elements with high layer thickness and therefore large volume, and the edge regions are built up from volume elements with smaller volumes, in which the positions of the volume elements are in addition individually adjusted along the z direction in order to obtain a high structural resolution at the surface.

[0032] In a preferred manner, the variation of the focal volume is such that the volume ratio between the largest and the smallest focal point volume during production of the component is at least 2, preferably at least 5. Preferably, it is provided that the change in the focal point volume occurs in at least one, preferably two, in particular three spatial directions perpendicular to each other.

[0033] The change in the focal point volume is preferably caused by a deflection of the individual beams by the associated acousto-optical modulator module in a direction transverse to the direction of travel of the respective writing beam, caused by a deflection unit, in particular a galvanometer scanner. If the galvanometer scanner moves the respective beam in the x direction, for example to solidify volume elements arranged one behind the other in the x direction, the associated acousto-optical modulator module can be controlled in such a way that the beam is moved back and forth at high speed transverse to its x direction, for example in the y direction. The amplitude of the previously mentioned back and forth movement determines the extent of the volume elements. By varying the amplitude, the focal point volume or the volume of the volume element to be solidified can be varied. The back and forth movement takes place in the x direction at a speed corresponding to at least 5 times, preferably at least 10 times, the speed in the direction of travel of the writing beam, caused by the deflection unit, in particular a galvanometer scanner. It will be understood that the above described method for changing the volume of the volume element to be solidified can be performed in a manner in which the x and y directions are reversed, such that the deflection unit moves the writing beam or focal point further in the y direction and the rapid reciprocating movement by the acousto-optical modulator module is transverse to the y direction, e.g. in the x direction.

[0034] The principle of multiphoton absorption is used in the context of the present invention to initiate a photochemical process in a photosensitive material bath. Multiphoton absorption methods include, for example, two-photon absorption methods. As a result of the photochemical reaction, there is a change in the material to at least one other state, which typically results in photopolymerization. The principle of multiphoton absorption is based on the fact that the photochemical process described above only occurs in areas of the beam path where there is a sufficient photon density for multiphoton absorption. The highest photon density occurs at the focal point of the optical imaging system, so that the probability that multiphoton absorption occurs only at the focal point is high. Outside the focal point, the photon density is lower, so that the probability of multiphoton absorption outside the focal point is too low to cause irreversible changes in the material due to photochemical reactions. Electromagnetic radiation can pass through the material largely unhindered at the wavelength used, and only at the focal point does an interaction occur between the photosensitive material and the electromagnetic radiation. The principles of multiphoton absorption are described, for example, in Zipfel et al., "Nonlinear magic: multiphoton microscopy in the biosciences," NATURE BIOTECHNOLOGY, Vol. 21, No. 11, November 2003.

[0035] The source of electromagnetic radiation may preferably be a collimated laser beam. The laser may emit one or several, fixed or variable wavelengths. In particular, the laser may be a continuous laser or a pulsed laser with pulse lengths in the nanosecond, picosecond or femtosecond range. Pulsed femtosecond lasers offer the advantage that lower average powers are required for multiphoton absorption.

[0036] A photosensitive material is defined as any material that is fluid or solid under the building conditions and that changes to a second state by multiphoton absorption in the focal point volume - for example by polymerization. The material change must be limited to the focal point volume and the immediate periphery of the focal point volume. The change in the material properties can be permanent, for example consisting in a change from a liquid state to a solid state, but the change can also be temporary. Incidentally, the permanent change can also be reversible or irreversible. The change in the material properties does not necessarily have to be a complete transition from one state to the other, but can also exist as a mixed form of both states.

[0037] The power of the electromagnetic radiation and the exposure time influence the quality of the produced components. By adjusting the radiation power and / or the exposure time, the volume of the focal point can be varied within a narrow range. If the radiation power is too high, additional processes occur which may lead to damage of the component. If the radiation power is too low, no permanent material property changes can occur. For each photosensitive material, there are therefore typical building process parameters which are associated with good component properties. In the context of the present invention, the components are preferably manufactured with a constant radiation power throughout the building process.

[0038] According to a second aspect of the invention, there is provided an apparatus for lithography-based generative production of three-dimensional components, in particular for carrying out the method according to the first aspect of the invention, comprising a material support for solidifiable material and an irradiation device which can be controlled for position-selective irradiation of the solidifiable material by at least one beam, wherein the irradiation device comprises a beam splitter for splitting an input beam into a plurality of beams, a deflection unit arranged downstream of the beam splitter in the beam path, and an optical imaging unit arranged downstream of the deflection unit for successively focusing each beam to a focal point in the material, as a result of which focusing in each case a volume element of the material located at the focal point can be solidified by means of multiphoton absorption, characterized in that a number of acousto-optical modulator modules corresponding to the number of beams are provided such that an acousto-optical modulator module comprising at least one acousto-optical modulator is arranged in the beam path of each beam.

[0039] Preferably, the acousto-optical modulator modules are designed to shift their respective focal points in the z-direction, where the z-direction corresponds to the direction of incidence of the associated beam into the material.

[0040] Preferably, the control unit of at least one acousto-optical modulator module comprises a frequency generator designed for periodic modulation of the acoustic wave frequency.

[0041] It is provided here that preferably the frequency generator is designed to vary the acoustic wave frequency gradient.

[0042] It is further preferred that the acousto-optical modulator modules are designed to shift their respective focal points in the x and / or y directions, the x and y directions corresponding to two orthogonal directions in a plane perpendicular to the direction of incidence of the respective beams.

[0043] As already mentioned in relation to the method according to the present invention, it is advantageous if the acousto-optical modulator module comprises at least two acousto-optical modulators, each arranged one behind the other in the beam path, and the at least two acousto-optical modulators preferably have directions of beam deflection of the at least two acousto-optical modulators that are essentially perpendicular to each other or have the same orientation of beam deflection of the at least two acousto-optical modulators.

[0044] Furthermore, the deflection unit may be formed by a galvanometer scanner arranged downstream of the acousto-optical modulator module in the beam path and designed in particular to effect a joint displacement of the focal point in an xy plane extending transversely to the z direction.

[0045] In particular, the illumination device can be designed to build up the component layer by layer extending in the xy plane, the transition from one layer to the next involving a change in the relative position of the optical imaging unit relative to the component in the z direction.

[0046] The illumination device is preferably designed in such a way that fine adjustment of the focal point in the z-direction takes place within the layer thickness of the layer by means of an acousto-optical modulator.

[0047] Furthermore, it can be stipulated that the material is present on a material support, such as in a trough, and that irradiation of the material is carried out from below, through the material support, which is transparent to the radiation at least in certain areas.

[0048] The build platform is preferably positioned at a distance from the material support, and the component is built up on the build platform by solidifying a volume element located between the build platform and the material support.

[0049] It is advantageous if the volume of the focal point is varied at least once during the building of the component, such that the component is built up from solidified volume elements of different volumes.

[0050] The imaging unit can be designed as an f-theta lens or preferably consists of a microscopy objective and relay optics in a 4f configuration, whereby the deflection unit and the objective are located in the focal plane of the corresponding lens.

[0051] The invention is explained in more detail below with reference to schematic examples of embodiment shown in the drawings. [Brief description of the drawings]

[0052] [Figure 1] FIG. 1 shows a schematic representation of a device according to the invention. [Diagram 2] FIG. 13 shows a detailed view of an alternative design of an acousto-optic modulator module. [Diagram 3] FIG. 13 shows a detailed view of an alternative design of an acousto-optic modulator module. [Figure 4] FIG. 13 shows a detailed view of an alternative design of an acousto-optic modulator module. [Diagram 5] FIG. 2 shows a schematic representation of focal points in an image field of a device during component production. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] In Fig. 1, a support is labelled 1, on which the component is to be placed. The support is coated with a photopolymerisable material 2, into which laser beams are focused, each laser beam being successively focused at a focal point in the photopolymerisable material, whereby a volume element of the material located at the focal point is solidified by means of multiphoton absorption. For this purpose, a laser beam is emitted from a radiation source 3, passed through a pulse compressor 4 and split into several beams (in this case four beams) in a beam splitter 5. A beam of light is now irradiated into the material 2 by means of an irradiation device 6. For this purpose, the irradiation device 6 comprises an acousto-optical modulator unit 7, a deflection mirror 8, a galvanometer scanner 9 and an optical imaging unit 10, which comprises an objective mirror that introduces the laser beam into the material 2 in the writing area.

[0054] The acousto-optical modulator unit 7 comprises a number of acousto-optical modulator modules 11 corresponding to the number of beams, at least one of which splits each beam into a zeroth order beam and a first order beam. The zeroth order beam is collected in a beam trap 12. The first order beam is directed via a relay lens 13 and a deflector 14 onto a deflection mirror 8, which directs the beam into a deflection unit 9 (e.g. a galvanometer scanner), where it is successively reflected by two mirrors 15. The mirrors 15 are driven to rotate about mutually orthogonal axes of rotation so that the beam can be deflected in both the x and y directions. The two mirrors 15 can each be driven by a galvanometer drive or an electric motor. The beam emerging from deflection unit 9 preferably passes through an optional relay lens system (not shown) and enters lens 10, which focuses the beam into the photopolymerizable material as already described.

[0055] To build up the component layer by layer, volume elements of one layer after the other are solidified in the material. To build up the first layer, the laser beam is focused, one after the other, in the material 2 to a focal point arranged in the focal plane of the lens 10. A joint deflection of the beam in the x, y plane is performed with the help of a deflection unit 9, whereby the writing range is limited by the lens 10. To move to the next plane, the lens 10, which is attached to the support 16, is moved in the z direction relative to the support 1 by the distance between the layers that corresponds to the layer thickness. Alternatively, the support 1 can also be adjusted relative to the fixed lens 10.

[0056] If the components to be produced are larger in the x and / or y direction than the writing range of the lens 10, substructures of the components are built up next to each other (so-called stitching). For this purpose, the support 1 is arranged on a cross table which can be moved in the x and / or y direction relative to the illumination device 6.

[0057] There is further provided a control unit 17 which controls the acousto-optical modulator unit 7, the deflection unit 9, the height adjuster 16 and the support 1 which is attached to the cross table.

[0058] As shown in Fig. 2, the acousto-optical modulator module 11 may have two acousto-optical modulators 18 arranged one behind the other, with the beam deflection directions coinciding. This has the advantage that the deflection is twice as large as compared to a single acousto-optical modulator, and that the deflections in the x, y and z directions can be controlled independently of each other. This means that any point in the available deflection range can be controlled, and fine adjustment of the focal point in the z direction is possible. The disadvantage of this arrangement is the astigmatism caused by the cylindrical lens effect of the acousto-optical modulator.

[0059] The acousto-optical modulators 11 each form a cylindrical lens effect that depends on the acoustic frequency gradient of the frequency modulation. The equivalent focal length Fl of the cylindrical lens can be calculated as follows:

number

number

[0060] In an alternative embodiment according to Fig. 3, the acousto-optical modulator module 11 comprises two acousto-optical modulators 18 arranged one after the other, whose beam deflection directions are perpendicular to each other. For the first beam to be deflected, this acousto-optical modulator module 11 acts as a cylindrical lens with an adjustable focal length, whereby the first beam has an adjustable divergence, which allows the focal point to be adjusted in the x and y directions, whereby the deflection direction of the deflection unit can be freely selected. Furthermore, this arrangement minimizes the resulting astigmatism, because two mutually orthogonal cylindrical lenses are produced.

[0061] Figure 4 shows a modified embodiment of the acousto-optical modulator module 11, which comprises a first pair of acousto-optical modulators 18 and a second pair of acousto-optical modulators 18, between which a relay lens 19 is arranged to ensure that the focal points at the input and output of the acousto-optical modulator module 11 are arranged on the same line. The two acousto-optical modulators 18 of each pair have the same direction of polarization. The direction of polarization of the modulators of the first pair is perpendicular to the direction of polarization of the modulators of the second pair. This has the effect of combining the advantages of the design shown in figure 2 with the advantages of the design shown in figure 3.

[0062] In Fig. 5 the writing area or image field 20 of the optical imaging unit 10 is shown in the x and y directions, whereby this writing area is a section of a component that can be built up between the optical imaging unit 10 and the component to be built up without changing the relative position in the x and y directions. Four focal points 21 can be identified, which are spaced apart so that four volume elements of the component can be produced simultaneously and independently of one another. The joint movement of the focal points 21 in the x direction occurs with the help of the deflection unit 9. The focal points 21 can furthermore be finely adjusted independently of one another in the x, y and / or z directions by means of the respective acousto-optical modulator modules 11, starting from their current basic positions determined by the deflection unit 9. For example, during the movement of the focal point in the x direction caused by the deflection unit 9, fine adjustments can be made in the z direction in order to adapt the position of the volume element to a curved or inclined component contour relative to the coordinate direction, similar to "grayscale lithography". Furthermore, during the movement of the focal point in the x direction caused by the deflection unit 9, fine adjustments can be made in the y direction in such a way that the laser beam is moved back and forth at high speed in order to be able to adjust the expansion of the volume element to be solidified in the y direction depending on the amplitude of the back and forth movement.

Claims

1. A method for lithography-based generative production of three-dimensional components, comprising: a beam emitted by an electromagnetic radiation source (3) being focused by means of an optical imaging unit (10) onto a focal point (21) in a material (2), said focal point (21) being displaced in said beam direction by means of a deflection unit (9) arranged upstream of said optical imaging unit (10), and wherein, as a result of said focusing and displacement, volume elements of said material (2) located at said focal point (21) are each subjected to multiphoton 1. A method for sequentially solidifying a material (2) by means of absorption, characterized in that the beam is split into a plurality of beams by a beam splitter (4), each of the plurality of beams being sequentially focused onto a focal point (21) in the material (2) by means of the deflection unit (9) and the optical imaging unit (10), and a number of acousto-optical modulator modules (11) corresponding to the number of beams are provided, such that an acousto-optical modulator module (11) for diffracting the beam is arranged in the beam path of each beam.

2. 2. The method of claim 1, wherein at least one of the acousto-optical modulator modules (11) is controlled to shift the focal point (21) of the associated beam in a z-direction, the z-direction corresponding to the direction of incidence of the respective beam into the material (2).

3. 2. The method of claim 1, wherein at least one of the acousto-optical modulator modules (11) is controlled to displace the focal point of the associated beam in the x and / or y direction, the x and y directions corresponding to two orthogonal directions in a plane perpendicular to the direction of incidence of the respective beam.

4. 2. The method according to claim 1, characterized in that at least two acousto-optical modulators (18) are used in each of the acousto-optical modulator modules (11), arranged one after the other in the beam path, and the at least two acousto-optical modulators (18) preferably have directions of beam deflection that are essentially perpendicular to each other or have the same orientation of the beam deflection.

5. 2. The method according to claim 1, characterized in that the beam is subjected to a joint deflection in the x and y directions by means of the deflection unit (9), in particular a galvanometer scanner, arranged in the beam path downstream of the acousto-optical modulator module (11).

6. 2. The method of claim 1, wherein the component is built up layer by layer by layers extending in the xy plane, and the transition from one layer to the next involves a change in the relative position of the optical imaging unit (10) relative to the component in the z direction.

7. 7. A method according to claim 6, characterized in that the focal point (21) is displaced in the z-direction by means of the acousto-optical modulator module (11) within the layer thickness of the layer.

8. 2. The method according to claim 1, characterized in that at least one of the focal points (21) is displaced in the z-direction by means of the acousto-optical modulator module (11) in order to form a curved outer contour of the component or an outer contour extending obliquely relative to the x, y plane, the sizes of the volume elements forming the outer contour being preferably selected to be the same.

9. An apparatus for the lithography-based generative production of three-dimensional components, in particular for carrying out the method according to any one of claims 1 to 8, comprising a material support (1) for a solidifiable material (2) and an irradiation device (6) that can be controlled for location-selective irradiation of the solidifiable material by at least one beam, the irradiation device (6) comprising a beam splitter (4) for splitting an input beam into a plurality of beams, a deflection unit arranged downstream of the beam splitter (4) in the beam path, and a deflection unit (9) below the deflection unit (9). and an optical imaging unit (10) arranged in series for successively focusing each beam onto a focal point (21) in the material (2), such that as a result of said focusing, each volume element of the material (2) located at the focal point (21) can be solidified by means of multiphoton absorption, characterized in that a number of acousto-optical modulator modules (11) corresponding to the number of beams are provided such that an acousto-optical modulator module (11) comprising at least one acousto-optical modulator (18) is arranged in the beam path of each beam.

10. 10. The device according to claim 9, characterized in that the acousto-optical modulator modules (11) are designed to displace the respective focal points (21) in the z-direction, the z-direction corresponding to the direction of incidence of the associated beam into the material (2).

11. 10. The device according to claim 9, characterized in that the at least one acousto-optical modulator (18) comprises a frequency generator designed for periodic modulation of an acoustic wave frequency.

12. 12. The device of claim 11, wherein the frequency generator is designed to vary the acoustic frequency gradient.

13. 10. The device according to claim 9, characterized in that the acousto-optical modulator modules (11) are designed to displace the respective focal points in the x and / or y direction, the x and y directions corresponding to two orthogonal directions in a plane perpendicular to the direction of incidence of the respective beams.

14. 10. The device according to claim 9, wherein the acousto-optical modulator module (11) comprises at least two acousto-optical modulators (18), each arranged one behind the other in the beam path, and the at least two acousto-optical modulators (18) preferably have directions of beam deflection of the acousto-optical modulators that are essentially perpendicular to each other or have the same orientation of beam deflection of the acousto-optical modulators.

15. 10. The device according to claim 9, characterized in that the deflection unit (9) is formed by a galvanometer scanner arranged in the beam path downstream of the acousto-optical modulator module (11) and designed in particular to achieve a common displacement of the focal point (21) in an x-y plane extending transversely to the z direction.

16. 10. The device according to claim 9, wherein the illumination device (6) is designed to build up the component layer by layer extending in the xy plane, the transition from one layer to the next comprising the change in the relative position of the optical imaging unit (10) relative to the component in the z direction.

17. 10. The device according to claim 9, characterized in that the illumination device (6) is designed in such a way that the displacement of the focal point (21) in the z-direction by means of the acousto-optical modulator module (11) occurs within a layer thickness of a layer.

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