Method and device for lithography-based generative manufacturing of three-dimensional components

Abstract

In a method for lithography-based additive manufacturing of three-dimensional components, a beam splitter 9 divides a beam into a plurality of beams, which are focused by an optical imaging unit 13 at a focal point within a material 2, the focal point being adjusted by deflection units 5, 19 arranged upstream of the optical imaging unit 13 in the beam direction, whereby volume elements of the material are sequentially solidified by multiphoton absorption at the focal point of each beam, a spatial light modulator 11 having a plurality of electronically controllable pixels is provided, these pixels being scanned by a plurality of beams and individually switched between at least one on-state and one off-state depending on the geometry of the component to be realized, as a result of which the associated beam is guided to the imaging unit 13 only in at least one on-state.

Description

Technical Field

[0001] The present invention relates to a method for lithography-based generative manufacturing of three-dimensional components, in which a beam emitted by an electromagnetic radiation source is split into a plurality of beams by a beam splitter, and these beams are focused at a focus within the material by an optical imaging unit, and the focus is displaced in the beam direction by a deflection unit arranged upstream of the optical imaging unit, whereby the volume elements of the material located at each focus are sequentially solidified by multiphoton absorption.

[0002] The present invention also relates to a device for lithography-based generative manufacturing of three-dimensional components.

Background Art

[0003] For example, from DE10111422A1, a method for component construction is known in which the solidification of a photosensitive material is performed by multiphoton absorption. For this purpose, a focused laser beam is irradiated onto a bath solution of the photosensitive material, whereby the irradiation conditions for the multiphoton absorption process that triggers solidification are satisfied only in the immediate vicinity of the focus, so that the focusing of the beam is guided to the region to be solidified within the bath volume according to the geometric data of the generated shaped body.

[0004] Since the volume elements of the material are solidified at each focus, adjacent volume elements are in close contact with each other, and the component is constructed by sequentially solidifying adjacent volume elements. The component can be constructed layer by layer, i.e., the volume elements of the first layer are solidified first before the volume elements of the next layer are solidified.

[0005] An irradiation device for a multi-photon absorption process comprises an optical system for focusing a laser beam and a deflection device for deflecting the laser beam. The deflection device is preferably designed to sequentially focus the beam on a focal point within the material located in exactly the same plane, which is perpendicular to the incident direction of the beam onto the material. In the x, y, z coordinate system, this plane is also called the x, y plane. The solidified volume elements generated by beam deflection in the x, y plane form a layer of the component. In order to enable the deflection device to operate continuously, the beam is interrupted or switched off between the solidification of two successive volume elements and then switched on again.

[0006] To build the next layer, the relative position of the components of the focusing optical system is changed in the z direction, which corresponds to the incident direction of at least one beam onto the material and extends perpendicular to the x, y plane. By adjusting the focusing optical system relative to the component (usually this is motorized), the focal point is shifted to a new x, y plane, which is spaced from the previous x, y plane by the desired layer thickness in the z direction.

[0007] By structuring a suitable material using multi-photon absorption, the advantage of extremely high structural resolution is obtained, whereby volume elements with a minimum structural size of 50 nm × 50 nm × 50 nm or less can be achieved. However, due to the small focal volume, the throughput of such a process is very low, for example, more than 10 3 points per mm 9 of volume need to be exposed. This leads to very long build times, which is the main cause of the low industrial utilization of the multi-photon absorption process.

[0008] In order to improve the component throughput without losing the possibility of high structural resolution, it has been proposed to vary the focal volume at least once during the construction of the component so that the component is constructed from solidified volume elements of different volumes. The variability of the focal volume enables high resolution (with a small focal volume). At the same time, a high writing speed (mm3 (measured in units of / h) can be achieved. By varying the focal volume, it becomes possible to combine high resolution with high throughput. The use of a change in the focal volume allows, for example, a large focal volume to be used inside the parts constructed to improve throughput and a smaller focal volume to be used on the surface of the parts to form the part surface with high resolution. The increase in the focal volume enables a higher structuring throughput because the volume of the material solidified during the exposure process is increased. To maintain high resolution at high throughput, a smaller focal volume can be used for finer structures and surfaces, and a larger focal volume can be used for coarser structures and / or to fill internal spaces. Methods and devices for changing the focal volume are described in WO2018 / 006108A1.

[0009] As another method for improving the writing speed, there is one that uses a beam splitter to split the writing beam into several writing beams each focused on the material to be solidified, enabling parallel solidification of a plurality of volume elements (Kelemen et al., "Parallel photopolymerization with complex light pattners generated by diffractive optical elements", Optics Express, Vol. 15, No. 22, pp. 14488 - 14497). However, since the individual writing beams cannot be placed independently of each other, only several similar parts corresponding to the number of beams can be generated.

[0010] In the field of stereolithography, it is known from U.S. Patent No. 5,536,467 that a plurality of writing beams are controlled independently of each other and deflected by separate mirrors to corresponding positions of a material in which each writing beam is solidified. However, as a drawback, since the deflection device includes a mechanically actuated mirror, the scanning speed is limited, and a device as shown may not be suitable for solidification of volume elements by multiphoton absorption. Also, the complexity of the apparatus increases in proportion to the number of writing beams that are moved independently of each other.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0012]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] The present invention aims to further develop a method and a device for lithography-based generative manufacturing of three-dimensional parts, without restricting part geometry and with little device effort, and with a further increased writing speed (measured in mm 3 / h).

Means for Solving the Problem

[0014] To solve this problem, a first aspect of the present invention provides, in a method of the type mentioned at the beginning, that a spatial light modulator is provided with a plurality of electronically controllable pixels, the plurality of electronically controllable pixels are raster scanned by a plurality of beams, and are individually switched between at least one on-state and an off-state according to the geometry of the part to be realized, so that each beam is guided to an imaging unit only in at least one on-state.

[0015] By using a spatial light modulator, it is possible to operate using a plurality of beams simultaneously, that is, using a plurality of beams deflected to move in the same direction by a deflection unit, and for each beam, it is possible to individually control whether a volume element is solidified by that beam at a specific position within the material. This enables parallel writing using a plurality of beams without each beam generating the same geometry and without the need to provide a separate deflection device for each beam.

[0016] In fact, the deflection unit causes a common deflection of all the beams, and thus these beams raster scan (scan) the pixels of the light modulator at a fixed pixel pitch. The number of pixels of the spatial light modulator corresponds to a multiple of the number of beams. Here, since each pixel can be switched between an on-state and an off-state regardless of the state of other pixels, it is possible to select whether the volume element corresponding to each pixel should be solidified within the material.

[0017] A pixel is a sub-region of a spatial light modulator, and irradiation of the pixel in its on-state by a beam causes solidification of volume elements within the material.

[0018] Due to a large number of pixels, a significant improvement in the writing speed is also achieved by the fact that the sum of the switching rates of all pixels is higher than that of conventional systems such as systems operating with an acousto-optic modulator. For example, since an acousto-optic modulator can switch the beam on and off at a rate of, for example, 50 MHz, 50 million volume elements can be written per second. Currently available spatial light modulators have a lower switching rate per pixel, and in the case of a two-dimensional array, the switching state of the entire pixel array can be changed at a rate of, for example, 180 Hz. However, by multiplying this by the number of pixels, an extremely high writing speed can be obtained. Thus, at the corresponding scanning speed of the deflection unit, for example, 360 megapixels can be written per second using a spatial light modulator having 2 million pixels and a switching rate of 180 Hz.

[0019] According to a preferred configuration of the present invention, the pixels of the spatial light modulator are arranged in at least one, for example exactly one, row extending along a straight line, and the splitting of the beam by a beam splitter is performed along the straight line such that the beam collides with the pixel row at intervals of only a plurality of pixels. The deflection of the beam by the deflection unit is also performed along the aforementioned straight line. For example, the beam splitter generates 50 beams that collide with the pixel row along the straight line at a distance of 20 pixels. Here, the deflection unit is controlled to deflect 50 beams together at an angle such that the beam sweeps 20 pixels, so that at the end of the deflection movement, each pixel of a 1000-pixel row is irradiated.

[0020] In the simplest case, a one-dimensional spatial light modulator in which pixels are arranged in a single line is used. Such a light modulator is also known as a line modulator, and the line modulator may be in the form of, for example, a "Grating Light Valve", that is, in the form of a dynamically adjustable diffraction grating. Each pixel is provided with a separately controllable diffraction grating, which includes, for example, a tiny metal piece that can be electrostatically moved up and down. This makes it possible to switch each pixel to move back and forth between the grating function and the reflection mirror.

[0021] In the case of a line modulator, beam deflection centered on only a single axis is required. The beam deflection can be performed, for example, by an acousto-optic deflector, whereby a very high deflection speed, and thus a high writing speed, can be achieved.

[0022] Since only the volume elements of the components located along the straight line can be solidified using the line modulator, the component or the material support needs to be laterally shifted with respect to the optical imaging unit for each column after each column in order to write another column.

[0023] According to a further preferred embodiment of the present invention, the pixels of the spatial light modulator are arranged in a plurality of parallel columns. With such a light modulator having a two-dimensional array of pixels, it is possible to solidify the volume elements in the material in a two-dimensional grid without the need to adjust the component or the material support with respect to the optical imaging unit.

[0024] The beam is preferably deflected about two axes that are perpendicular to each other. Thereby, for the deflection about the first axis (corresponding to the axis perpendicular to the beam splitting), a high-speed scanner can be used, and for the deflection about the second axis, a slower scanner is sufficient. For example, the beam deflection about the first axis is performed using a resonant scanner or a polygon scanner, and the beam deflection about the second axis is performed using a galvanometer scanner.

[0025] A light modulator having a two-dimensional array of pixels can preferably be designed as a reflective liquid crystal microdisplay. Such a light modulator is also referred to as a "liquid crystal on silicon device" or "LCoS device".

[0026] Furthermore, by using the spatial light modulator according to the present invention, it becomes possible to simply adjust the radiation intensity of the beam focused on the material for each pixel in order to achieve so-called "gray scaling". In this regard, a preferred embodiment of the method according to the present invention provides that at least one on-state includes at least a first on-state and a second on-state, and the pixel is individually switched between an off-state and the first on-state and the second on-state, and the first on-state and the second on-state generate different radiation intensities at the focus. This gray scale function provides the advantage that the intensity of the introduced radiation can be controlled for each pixel.

[0027] This can be used to achieve the equalization of the radiation power over all volume elements, i.e., to ensure that each volume element of the material is irradiated with the same radiation power. Adjusting or reducing the radiation intensity is advantageous, for example, for volume elements that are located at the inflection point of the beam deflection and can thus be irradiated longer than the volume elements located therebetween. The same applies to volume elements or pixels that are covered twice during raster scanning. In this regard, a preferred configuration of the present invention enables the adjustment of the radiation intensity of each pixel of the spatial light modulator, and provides that the radiation intensity is set according to the exposure time of the pixel so that the volume elements receive the same radiation power. For this purpose, a suitable control unit for adjusting the radiation intensity according to the exposure duration is provided.

[0028] As an alternative or in addition, the adjustment of the radiation intensity can also be used to vary the radiation power of individual volume elements in order to achieve a height profile in the z - direction without changing the relative position between the imaging unit and the build platform. In this context, a preferred configuration of the invention provides that the radiation intensity of each pixel of the spatial light modulator is adjustable, and in particular in the irradiation direction, the radiation intensity is set such that the volume elements receive different radiation powers in order to generate volume elements having different spatial dimensions from each other. The radiation power is preferably set by a suitable control unit.

[0029] The spatial light modulator is usually designed such that the incident light beam is reflected in at least one on - state of each pixel. To enable as simple a structure as possible that allows the spatial light modulator to be arranged between a deflection unit and a beam splitter on one side and an optical imaging unit on the other side, a preferred embodiment of the invention provides that a plurality of beams are directed towards the spatial light modulator via a polarization beam splitter, the beams are reflected by the spatial light modulator through the pixels in the on - state, collide with the polarization beam splitter with the polarization changed, and the polarization beam splitter directs the beams towards the optical imaging unit.

[0030] In a preferred further refinement of the above setup, a mirror can be provided, whereby the spatial light modulator and the mirror are displaced such that either the spatial light modulator or the mirror can be optionally moved to an operating position arranged in the beam path. This enables switching between writing parts using the light modulator according to the invention and parallel writing of conventional similar parts.

[0031] In another further refinement, the beam splitter can be designed as a spatial light modulator for generating static holograms or dynamic light modulation.

[0032] Preferably, the components are constructed in layers by a layer extending in the x-y plane, whereby the change from one layer to the next involves changing the relative position of the optical imaging unit with respect to the component in the z-direction extending perpendicular to the x-y plane. The z-direction basically corresponds to the incident direction of a plurality of writing beams.

[0033] A preferred method is obtained when the material is present on a material support such as in a bath and the irradiation of the material is performed from below through a material support that is at least partially transparent to the radiation. The build platform can be placed at a distance from the material support, and the component can be built on the build platform by solidifying the material between the build platform and the material support. Alternatively, it is also possible to irradiate the material from above.

[0034] The principle of multi-photon absorption is used in connection with the present invention to initiate a photochemical process in a photosensitive material bath.

[0035] The multi-photon absorption method also includes, for example, a two-photon absorption method. As a result of the photochemical reaction, the material changes to at least one other state, typically photopolymerization occurs. The principle of multi-photon absorption is based on the fact that the aforementioned photochemical process occurs only in a region of the beam path where there is a sufficient photon density for multi-photon absorption. The highest photon density occurs at the focus of the optical imaging system, whereby the probability of multi-photon absorption occurring only at the focus is sufficiently high. Outside the focus, the photon density is low, and the probability of multi-photon absorption outside the focus is too low to cause an irreversible change in the material through the photochemical reaction. The electromagnetic radiation can pass through the material with little attenuation at the wavelengths used, and the interaction between the photosensitive material and the electromagnetic radiation occurs only at the focus. The principle of multi-photon absorption is described, for example, in Zipfel et al., "Nonlinear magic: multiphoton microscopy in the biosciences", NATURE BIOTECHNOLOGY, Vol. 21, No. 11, November 2003.

[0036] The source of electromagnetic radiation can preferably be a collimated laser beam. The laser can emit one or more fixed or variable wavelengths. In particular, this is a continuous laser or a pulsed laser having a pulse length in the nanosecond, picosecond, or femtosecond range. Pulsed femtosecond lasers have the advantage of low average power required for multiphoton absorption.

[0037] The photosensitive material is any material that is fluid or solid under the construction conditions and changes to a second state through multiphoton absorption in the focal volume, for example, through polymerization. The material change needs to be restricted to the focal volume and its immediate surroundings. The change in the substance properties can be permanent, for example, consisting of a change from a liquid to a solid state, but can also be merely temporary. Also, the permanent change can 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 and can also be a mixture of both states.

[0038] According to a second aspect of the present invention, there is provided a device for lithography-based generative manufacturing of three-dimensional components, in particular for carrying out the method according to the first aspect of the present invention. The device comprises a material support for a solidifiable material and an irradiation device controllable for the selective irradiation of the solidifiable material with at least one beam. The irradiation device comprises a beam splitter for splitting an input beam into a plurality of beams, a deflection unit arranged upstream or downstream of the beam splitter in the beam path, and an optical imaging unit arranged downstream of the deflection unit and the beam splitter for sequentially focusing each beam onto a focus within the material, whereby respective volume elements of the material located at the focus can be solidified by multiphoton absorption. The device is characterized in that a spatial light modulator having a plurality of electronically controllable pixels is arranged between the imaging unit on the one hand and the beam splitter and the deflection unit on the other hand, and the plurality of electronically controllable pixels can be scanned by the plurality of beams and can be individually switched between at least one on-state and an off-state, so that each beam is guided to the imaging unit only in at least one on-state.

[0039] Diffractive optical elements can be used as beam splitters such as the 1D diffractive beam splitters MS-802-I-Y-A or MS-304-Y-I-Y from HOLO / OR Ltd.

[0040] For example, an acousto-optic modulator, a resonant scanner, a polygon scanner, a galvanometer scanner, or a combination thereof can be used as the deflection unit.

[0041] The beam splitter can be arranged either in front of or behind the deflection unit. Considering the limited angular tolerance of the beam splitter, arranging the beam splitter behind the deflection unit is an option only when the maximum deflection angle is relatively small. For larger deflection angles, it is preferred that the deflection unit is arranged behind the beam splitter.

[0042] According to a preferred configuration, the spatial light modulator comprises a one-dimensional array of pixels. In particular, the spatial light modulator may comprise a dynamically adjustable diffraction grating. As already explained with respect to the first aspect of the present invention, here, a so-called line modulator can be used. The line modulator can change the state of individual pixels at a frequency of at least 300 MHz, whereby a very high scanning speed, and thus a very high writing speed, can be achieved.

[0043] The deflection unit can preferably comprise at least one acousto-optic modulator, and the acousto-optic modulator can be arranged in front of the deflection unit. The acousto-optic modulator is an optical component that affects the frequency, propagation direction, and / or intensity of the incident light. For this purpose, an optical grating is generated by sound waves in a transparent solid, and the light beam is diffracted in this optical grating. In a configuration known as an acousto-optic deflector, this can be used to generate beam deflection, and thus the deflection angle is determined according to the relative wavelength of the light and the sound waves in the transparent solid. The deflection angle can be adjusted by changing the sound wave frequency.

[0044] According to a further preferred configuration, it is provided that the spatial light modulator comprises a two-dimensional array of pixels. In this context, the spatial light modulator may be designed, for example, as a reflective liquid crystal microdisplay. Such an LCoS device has a frame rate of more than 60 Hz, which means that the entire pixel grid can be changed more than 60 times per second with respect to the state of the pixels. Assuming that the time required to change the layers is not taken into account in the case of the layered structure of the components, at least 60 volume elements per second can be generated in the material.

[0045] When scanning a two-dimensional pixel grid with a plurality of beams, preferably, the deflection unit is configured as a two-axis deflection unit, and preferably, a resonant scanner or a polygon scanner for beam deflection about a first axis and a galvanometer scanner for beam deflection about a second axis are provided.

[0046] In another preferred embodiment, a polarization beam splitter is assigned to the spatial light modulator, through which a plurality of beams are directed at the spatial light modulator, and the polarization beam splitter redirects the beam reflected by the spatial light modulator towards the optical imaging unit.

[0047] The polarization of the beam is preferably achieved by arranging a wave plate, in particular a λ / 2 plate or a λ / 4 plate, between the polarization beam splitter and the spatial light modulator. This rotates the polarization of the beam, effecting an overall change of 90° at the polarization beam splitter.

[0048] A preferred extension of the described arrangement of the light modulator is that a mirror is provided and the spatial light modulator and the mirror can be displaced such that either the spatial light modulator or the mirror can be moved to an operating position arranged in the beam path.

[0049] Preferably, the irradiation device is designed to build the components layer by layer with a layer extending in the x-y plane, and the change from one layer to the next includes a change in the relative position of the optical imaging unit with respect to the component in the z direction perpendicular to the x-y plane.

[0050] Furthermore, it may be provided that the material is present on a material support, such as in a tank, and the irradiation of the material takes place from below through a material support that is at least partially transmissive to the radiation.

[0051] The build platform is preferably positioned at a distance from the material support, and the components are built on the build platform by solidifying the volume elements located between the build platform and the material support.

[0052] The imaging unit can be designed as an f-theta lens or preferably consists of a microscope lens and a relay optical system in a 4f configuration where the deflection unit and the objective lens are located in the focal plane of the corresponding lenses.

[0053] The present invention will be described in more detail below with reference to the schematic embodiments shown in the drawings.

Brief Description of the Drawings

[0054]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0055] In FIG. 1, the support is labeled 1, and components are constructed on this support. The support 1 is coated with a photopolymerizable material 2, and a laser beam is focused on this photopolymerizable material 2. As a result, each laser beam is sequentially focused on the focal point within the photopolymerizable material, and the volume elements of the material located at the focal point are solidified by multi-photon absorption. For this purpose, the laser beam is emitted from a radiation source 3, passed through a pulse compressor 4, and uniaxially deflected by an acousto-optic modulator module 5 having two acousto-optic modulators 6 to move back and forth. The zero-order beam is collected by a beam trap 7. The first-order beam is guided to a beam splitter 9 via a relay system 8, and the beam splitter 9 divides the beam into a plurality of beams, and these beams are guided to a polarization beam splitter 10 via a scanning lens 17. The polarization beam splitter is designed to transmit a plurality of beams in the direction of the spatial light modulator 11. The beam passes through a wave plate 12, and this wave plate 12 relatively delays the polarization component, for example, by λ / 4. The polarization of the beam reflected by the spatial light modulator 11 is rotated again in the wave plate 12 so that when the beam hits the polarization beam splitter 10, it is deflected in the direction of the optical imaging unit 13. The beam reaches the optical imaging unit 13 via a tube lens 14. The optical imaging unit 13 includes an objective lens that focuses the laser beam within the writing area on the material 2.

[0056] In the configuration according to FIG. 1, the spatial light modulator 11 is designed as a line modulator and includes a plurality of pixels arranged in a row. Each pixel can be switched between an on state and an off state, for example, by an electronically controllable diffraction grating, whereby each beam is reflected by the polarization beam splitter 10 only in the on state and then guided to the optical imaging unit 13.

[0057] The beam splitter 9 is configured to generate a plurality of beams distributed along the pixel column, and the deflection unit 5 is configured to displace the plurality of beams together along the pixel column, that is, to scan the pixel column. Depending on whether each pixel is in the on state or the off state, the beam is reflected by the optical modulator and introduced into the material 2 at the corresponding position.

[0058] After scanning the pixel column and generating corresponding solidified volume elements arranged in a column extending, for example, in the y direction in the material 2, the support 1 is arranged on an X-Y table displaceable in the x direction with respect to the optical imaging unit 13, so that the change to the next column is made. In this way, the volume elements can be generated in a number of lines. This is schematically shown in FIG. 4.

[0059] FIG. 4 shows, for example, a column 23 of pixels 24 extending in the x direction. In this example, the beam splitter generates two beams 25 arranged at an inter-pixel distance of 6 pixels. The deflection device scans the pixel column 23 by moving this group of two beams 25 according to the arrow 26. The volume element is solidified at the points represented by the dark pixels. This is achieved by switching these pixels to the on state in the optical modulator. After scanning the column 23, the support 1 is shifted by one unit in the y direction, so that, as shown by the arrow 29, in addition to the previously solidified volume element, further volume elements can be solidified. When the pixel column is scanned, other pixels are switched to the on state, and after passing through several lines, the pattern shown in FIG. 4 is generated.

[0060] In order to build the component layer by layer, the volume elements are solidified one layer at a time in the material 2. To build the first layer, the laser beams are sequentially focused on the foci arranged on the focal plane of the optical imaging unit 13 in the material 2 respectively. To change to the next plane, the optical imaging unit 13 attached to the support 15 is moved in the z direction by the layer distance with respect to the support 1. Alternatively, the support 1 can also be adjusted with respect to the fixed optical imaging unit 13.

[0061] Furthermore, a control unit 16 is provided, and this control unit 16 controls the deflection unit 5, the beam splitter 9, the optical modulator 11, the height adjuster 15, and the support 1 attached to the X-Y table.

[0062] In the configuration shown in FIG. 2, unlike the configuration shown in FIG. 1, the spatial light modulator 11 includes a two-dimensional pixel grid. Therefore, a deflection unit 19 is provided that can deflect a plurality of beams generated by the beam splitter 9 about two perpendicular axes. For this purpose, the deflection unit 19 includes a first scanner 20 and a second scanner 21, and these scanners are controlled such that the first scanner scans a pixel column (in the x direction) as described with respect to the configuration according to FIG. 1, and the second scanner deflects the beam laterally with respect thereto from one column to the next column (in the y direction). A further difference from the configuration according to FIG. 1 is that the deflection unit 19 is arranged behind the beam splitter 9. Furthermore, an acousto-optic modulator 18 is arranged in front of the beam splitter 9, and this acousto-optic modulator 18 serves to set a global power limit and limit the power at the turning point of the scanner in order to prevent damage to the modulator.

[0063] By using the spatial light modulator 11 of the two-dimensional pixel array, volume elements can be generated within the two-dimensional writing region of the optical imaging unit 13. If the generated parts are larger in the x direction and / or the y direction than the writing region of the optical imaging unit 13, the sub-structures of the parts are constructed adjacent to each other (so-called stitching). For this purpose, the support 1 is arranged on the X-Y table, and the X-Y table can be moved in the x direction and / or the y direction with respect to the optical imaging unit 13.

[0064] The configuration according to FIG. 3 differs from the configuration according to FIG. 2 in that when the function of the optical modulator 11 can be omitted, the mirror 22 can be moved into the beam path instead of the spatial light modulator 11.

[0065] The raster scan of the two-dimensional pixel grid of the spatial light modulator is shown in FIGS. 5 and 6. Here, the individual pixels are also labeled 24, and it can be seen that the pixel 24 is provided in a plurality of lines, i.e., in a two-dimensional array. In the embodiment according to FIG. 5, the beam splitter generates four beams 25 in a square arrangement, whereby each individual beam is two-dimensionally moved across the pixel grid along a path labeled 28 by means of a deflection device. For example, by means of an acousto-optic deflector, the beam is deflected in the direction of the double-headed arrow 26 (x-direction), and for example, by means of a galvanometer scanner, the beam is deflected in the direction of the double-headed arrow 27 (y-direction). By switching between the on-state and the off-state, the pattern shown in FIG. 5 is generated, whereby the volume element is solidified at the points (on-state) represented by the dark pixels.

[0066] In the embodiment according to FIG. 6, the beam splitter generates three beams 25 in a linear arrangement, whereby each individual beam is two-dimensionally moved across the pixel grid along a path labeled 28 by means of a deflection device. For example, by means of a resonant scanner, the beam is deflected in the direction of the double-headed arrow 26 (x-direction), and for example, by means of a galvanometer scanner, the beam is deflected in the direction of the double-headed arrow 27 (y-direction).

Claims

1. A method for lithography-based generative manufacturing of three-dimensional components, wherein a beam emitted by an electromagnetic radiation source (3) is split into a plurality of beams by a beam splitter (9), the plurality of beams are focused by an optical imaging unit (13) onto a focal point within a material (2), and the focal point is displaced by a deflection unit (5, 19) arranged upstream of the optical imaging unit (13) in the beam direction, whereby the volume elements of the material (2) located at each of the focal points are successively solidified by multi-photon absorption. In the method, a spatial light modulator (11) is provided with a plurality of electronically controllable pixels, the plurality of electronically controllable pixels are scanned by the plurality of beams, and are individually switched between at least one on-state and an off-state according to the geometry of the component to be realized, so that each of the beams is guided to the imaging unit (13) only in the at least one on-state. The method is characterized by this.

2. The at least one on-state includes at least a first on-state and a second on-state, the pixels are individually switched between the off-state, the first on-state and the second on-state, and the first on-state and the second on-state generate different radiation intensities at the focal point. The method according to claim 1, characterized by this.

3. The radiation intensity of each pixel of the spatial light modulator is adjustable, and the radiation intensity is adjusted according to the exposure time of the pixel so that the volume elements receive the same radiation power. The method according to claim 1 or 2, characterized by this.

4. The radiation intensity of each pixel of the spatial light modulator is adjustable, and in particular in the irradiation direction, the radiation intensity is adjusted so that the volume elements receive different radiation powers in order to generate volume elements having different spatial dimensions from each other. The method according to claim 1 or 2, characterized by this.

5. The pixels of the spatial light modulator (11) are arranged in at least one, for example exactly one, row extending along a straight line, and the splitting of the beam is performed by the beam splitter (9) along the straight line so that the beam impinges on the pixel row at intervals of a plurality of pixels. The method according to any one of claims 1 to 4, characterized by this. Claim 6 The pixels of the spatial light modulator (11) are arranged in a plurality of parallel columns, and the plurality of beams are deflected about two axes which are preferably perpendicular to each other. The beam deflection about the first axis is preferably performed by a polygon scanner or a resonant scanner (121), and the beam deflection about the second axis is preferably performed by a galvanometer scanner (20). The method according to claim 5, characterized in that. Claim 7 The plurality of beams are directed to the spatial light modulator (11) via a polarization beam splitter (10), the beams are reflected by the spatial light modulator (11), collide with the polarization beam splitter (10) in a state where the polarization is changed, and the polarization beam splitter (10) directs the beams to the optical imaging unit (13). The method according to any one of claims 1 to 6, characterized in that. Claim 8 A mirror (22) is provided, and the spatial light modulator (11) and the mirror (22) are displaced so that either the spatial light modulator (11) or the mirror (22) is moved to an operating position arranged in the beam path. The method according to any one of claims 1 to 7, characterized in that. Claim 9 The components are constructed layer by layer by a layer extending in the x-y plane, and the change from one layer to the next includes a change in the relative position of the optical imaging unit (13) with respect to the component in the z direction extending perpendicular to the x-y plane. The method according to any one of claims 1 to 8, characterized in that. Claim 10 A device for lithography-based generative manufacturing of three-dimensional components for carrying out the method according to any one of claims 1 to 9, the device comprising: a material support (1) for a curable material (2); an irradiation device controllable for selectively irradiating the curable material with at least one beam; the irradiation device comprising: a beam splitter (9) for splitting an input beam into a plurality of beams; a deflection unit (5, 19) arranged upstream or downstream of the beam splitter (9) in the beam path; and an optical imaging unit (13) arranged downstream of the deflection unit (5, 19) and the beam splitter (9) for sequentially focusing each beam onto a focus within the material (2), whereby a volume element of the material (2) located at each respective focus can be cured by multiphoton absorption; characterized in that a spatial light modulator (11) having a plurality of electronically controllable pixels is arranged between the imaging unit (13) on one side and the beam splitter (9) and the deflection unit (5, 19) on the other side, the plurality of electronically controllable pixels can be scanned by the plurality of beams, and can be individually switched between at least one on-state and an off-state, such that each beam is guided to the imaging unit (13) only in the at least one on-state.

11. The device according to claim 10, wherein the at least one on-state comprises at least a first on-state and a second on-state, the pixels are individually switchable between the off-state, the first on-state and the second on-state, and the first on-state and the second on-state generate different radiation intensities at the focus.

12. The device according to claim 10 or 11, wherein the spatial light modulator (11) comprises a one-dimensional array of the pixels.

13. The device according to any one of claims 10 to 12, wherein the spatial light modulator (11) comprises a dynamically adjustable diffraction grating.

14. The device according to any one of claims 10 to 13, wherein the deflection unit (5) comprises at least one acousto-optic modulator.

15. The device according to claim 10 or 11, characterized in that the spatial light modulator (11) comprises a two-dimensional array of said pixels.

16. The device according to claim 15, characterized in that the spatial light modulator (11) is designed as a reflective liquid crystal microdisplay.

17. The device according to claim 15 or 16, characterized in that the deflection unit (19) is designed as a two-axis deflection unit, preferably comprising a polygon scanner or resonant scanner (21) for beam deflection about a first axis and a galvanometer scanner (20) for beam deflection about a second axis.

18. The device according to any one of claims 10 to 17, characterized in that a polarization beam splitter (10) is assigned to the spatial light modulator (11), through which the plurality of beams are directed towards the spatial light modulator (11), and the polarization beam splitter (10) deflects the beam reflected by the spatial light modulator (11) towards the optical imaging unit (13).

19. The device according to claim 18, characterized in that a wave plate (12), in particular a λ / 2 plate or a λ / 4 plate, is arranged between the polarization beam splitter (10) and the spatial light modulator (11).

20. The device according to any one of claims 10 to 19, characterized in that a mirror (22) is provided and the spatial light modulator (11) and the mirror (22) can be displaced such that either the spatial light modulator (11) or the mirror (22) can be moved to an operating position arranged in the beam path.

21. The device according to any one of claims 10 to 20, characterized in that the irradiation device is designed to build the components layer by layer with a layer extending in the x-y plane, and a change from one layer to the next includes a change in the relative position of the optical imaging unit (13) with respect to the component in the z direction perpendicular to the x-y plane.

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