Methods and devices for lithography-based generative manufacturing of three-dimensional parts

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 onto a focus within a 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 multi-photon 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 multi-photon absorption. For this purpose, a focused laser beam is irradiated onto a bath solution of the photosensitive material, and thus the irradiation conditions for the multi-photon absorption process that triggers solidification are satisfied only in the immediate vicinity of the focusing, 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 adhere to each other, and the component is constructed by sequentially solidifying adjacent volume elements. The component can be constructed in layers, i.e., the volume elements of the first layer are solidified first before the volume elements of the next layer are solidified.

[0005] An illumination device for a multiphoton 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 to a focal point in the material located in the exact same plane, perpendicular to the direction of incidence of the beam into the material. In the x,y,z coordinate system, this plane is also called the x,y plane. The solidified volume elements produced by the beam deflection in the x,y plane form layers of material. To enable the deflection device to operate continuously, the beam is interrupted or turned off between the solidification of two sequential volume elements and then turned back on.

[0006] To construct the next layer, the relative position of the focusing optical system to the component is changed in the z-direction, which corresponds to the direction of incidence of at least one beam into the material and extends perpendicular to the x,y plane. By adjusting the focusing optical system relative to the component (this is usually done electrically), the focus is shifted to a new x,y plane, which is separated from the previous x,y plane by the desired layer thickness in the z-direction.

[0007] By structuring suitable materials using multiphoton absorption, the advantage of extremely high structural resolution can be obtained, thereby enabling the achievement of volume elements with a minimum structural size of 50 nm × 50 nm × 50 nm or less. However, due to the small focal volume, the throughput of such a process becomes very low, for example, 1 mm 3 10 per volume 9 Exposure beyond a single point is required. This leads to extremely long construction times, which is the main reason for the low industrial application of multiphoton absorption processes.

[0008] To improve component throughput without sacrificing the potential for high structural resolution, it has been proposed to change the focal volume at least once during component construction so that the component is constructed from solidified volume elements of different volumes. The variability of the focal volume enables high resolution (at small focal volumes) and simultaneously allows for high write speeds (mm) (at large focal volumes).3 High throughput (measured in units of / h) can be achieved. By changing the focal volume, high resolution can be combined with high throughput. By using variations in focal volume, for example, a larger focal volume can be used inside a component being constructed to improve throughput, and a smaller focal volume can be used on the surface of a component to form the component surface with high resolution. Increasing the focal volume enables higher structured throughput because the volume of material solidified during the exposure process increases. 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] Another method to improve writing speed involves using a beam splitter to divide the writing beam into several writing beams, each focused onto the material being solidified, thereby enabling the parallel solidification of multiple volume elements (Kelemen et al., "Parallel photopolymerization with complex light patterns 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 a few similar components corresponding to the number of beams can be generated.

[0010] In the field of stereolithography, U.S. Patent No. 5,536,467 describes a system in which multiple writing beams are controlled independently of each other, and each writing beam is deflected by a separate mirror to the corresponding position in the material to be solidified. However, a drawback is that the scanning speed is limited because the deflection device uses mechanically operated mirrors, and such a device is not suitable for solidifying volume elements by multiphoton absorption. Furthermore, the complexity of the apparatus increases proportionally to the number of writing beams that are moved independently of each other. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] DE10111422A1 [Patent Document 2] WO2018 / 006108A1 [Patent Document 3] U.S. Patent No. 5,536,467 [Non-patent literature]

[0012] [Non-Patent Document 1] Kelemen et al., "Parallel photopolymerization with complex light patterns generated by diffractive optical elements," Optics Express, Vol. 15, No. 22, pp. 14488-14497. [Non-Patent Document 2] Zipfel et al., "Nonlinear magic: multiphoton microscopy in the biosciences," NATURE BIOTECHNOLOGY, Vol. 21, No. 11, November 2003. [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] This invention allows for the creation of a component geometry without constraints and with minimal equipment effort (mm 3 The aim is to further develop methods and devices for lithography-based generative manufacturing of three-dimensional parts, which will result in even greater write speeds (measured in units of / h). [Means for solving the problem]

[0014] To solve this problem, a first aspect of the present invention provides that, in the type of method described at the beginning, the 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 individually switched between at least one on state and an off state depending on the geometry of the component to be realized, so that each beam is guided to the imaging unit only in at least one on state.

[0015] The spatial light modulator allows for the simultaneous use of multiple beams, specifically multiple beams deflected in the same direction by a deflection unit, and enables individual control over whether a volume element is solidified by that beam at a specific location within the material. This allows for parallel writing using multiple beams without each beam generating the same geometry and without the need for separate deflection devices for each beam.

[0016] In fact, the deflection unit causes a common deflection for all beams, and these beams raster scan (scan) the pixels of the optical modulator at a fixed pixel spacing. The number of pixels in the spatial optical modulator corresponds to a multiple of the number of beams. Here, since each pixel can be switched between an on and off state regardless of the state of the other pixels, it is possible to select whether or not the volume element corresponding to each pixel should be solidified in the material.

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

[0018] The large number of pixels also leads to a significant improvement in writing speed, due to the fact that the sum of the switching rates of all pixels is higher than in conventional systems, such as systems operating with acousto-optic modulators. Acousto-optic modulators can switch the beam on and off at a rate of, for example, 50 MHz, allowing for the writing of 50 million volume elements per second. Currently available spatial light modulators have lower switching rates per pixel, and in the case of a two-dimensional array, the entire pixel array can change its switching state at a rate of, for example, 180 Hz. However, by multiplying this by the number of pixels, extremely high writing speeds can be obtained. Thus, at the corresponding scanning speed of the deflection unit, for example, 360 megapixels per second can be written using a spatial light modulator with 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, just one, column extending along a straight line, and beam splitting by a beam splitter is performed along the straight line such that the beams collide with the pixel column at intervals of several pixels. Beam deflection by a deflection unit is also performed along the aforementioned straight line. For example, the beam splitter generates 50 beams that collide with the pixel column along the straight line at a distance of 20 pixels. Here, the deflection unit is controlled to deflect the 50 beams together at a certain angle so that the beams sweep the 20 pixels, so that at the end of the deflection movement, each pixel in a column of 1000 pixels is illuminated.

[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", i.e., 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 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 shifted laterally 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. Such a light modulator having a two-dimensional array of pixels enables the solidification of 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, whereby a high-speed scanner can be used for the deflection about the first axis (corresponding to the axis perpendicular to the beam splitting), and a slower scanner is sufficient for the deflection about the second axis. 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] An optical modulator having a two-dimensional array of pixels can preferably be designed as a reflective liquid crystal microdisplay. Such an optical modulator is also called a "liquid crystal on silicon device" or "LCoS device".

[0026] Furthermore, the use of the spatial light modulator according to the present invention enables simple pixel-by-pixel adjustment of the radiant intensity of the beam focused onto the material in order to achieve so-called "grayscaling." 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 that pixels are individually switched between an OFF state and the first ON state and the second ON state, the first ON state and the second ON state producing different radiant intensities at the focal point. This grayscaling function provides the advantage that the intensity of the introduced radiation can be controlled on a pixel-by-pixel basis.

[0027] This can be used to achieve uniformity of radiant power across all volume elements, i.e., to ensure that each volume element of the material is irradiated with the same radiant power. Adjusting or reducing the radiant intensity is advantageous, for example, with respect to volume elements that are located at the reversal point of beam deflection and therefore may be irradiated for a longer period than volume elements located between them. 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 provides that the radiant intensity of each pixel of the spatial light modulator is adjustable, and that the radiant intensity is set according to the exposure time of the pixel so that the volume elements receive the same radiant power. For this purpose, a suitable control unit is provided that adjusts the radiant intensity according to the exposure duration.

[0028] Alternatively or additionally, adjusting the radiant intensity may also be used to vary the radiant power of individual volume elements to achieve a height profile in the z-direction without changing the relative position between the imaging unit and the build platform. In this regard, a preferred configuration of the present invention provides that the radiant intensity of each pixel of the spatial light modulator is adjustable, and that the radiant intensity is set such that the volume elements receive different radiant powers from one another in order to produce volume elements having different spatial dimensions from one another, particularly in the irradiation direction. The radiant power is preferably set by a suitable control unit.

[0029] A spatial light modulator is typically designed so that an incident light beam is reflected in at least one ON state of each pixel. To enable the simplest possible structure that allows the spatial light modulator to be positioned between a deflection unit and beam splitter on one side and an optical imaging unit on the other, a preferred embodiment of the present invention provides that multiple beams are directed to a spatial light modulator via a polarizing beam splitter, the beams are reflected by the spatial light modulator through pixels that are in the ON state, and collide with the polarizing beam splitter with altered polarization, which then directs the beams to the optical imaging unit.

[0030] A preferred further improvement to the above setup is that a mirror may be provided, thereby displacing the spatial light modulator and the mirror so that either the spatial light modulator or the mirror can be optionally moved to an operating position located in the beam path. This allows switching between writing components using the optical modulator according to the present invention and parallel writing of similar components in the conventional manner.

[0031] In another further improvement, the beam splitter could be designed as a spatial light modulator that generates static holograms or dynamic optical modulation.

[0032] Preferably, the component is constructed in layers by layers extending in the xy plane, so that changing 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, which extends perpendicular to the xy plane. The z direction essentially corresponds to the incident direction of multiple writing beams.

[0033] A preferred method is obtained when the material is present on a material support, such as in a tank, and the irradiation of the material is carried out from below through a material support that is at least partially permeable to radiation. The build platform can be placed at a distance from the material support, and the components can be constructed 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 multiphoton absorption is used in connection with the present invention to initiate photochemical processes in a photosensitive material bath.

[0035] Multiphoton absorption methods also include, for example, two-photon absorption methods. As a result of the photochemical reaction, the material changes to at least one other state, typically resulting in photopolymerization. The principle of multiphoton absorption is based on the fact that the aforementioned photochemical processes occur only in regions 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, which makes it highly probable that multiphoton absorption occurs only at the focal point. Outside the focal point, the photon density is low, and the probability of multiphoton absorption outside the focal point is too low to cause irreversible changes in the material through the photochemical reaction. Electromagnetic radiation can pass through the material largely unobstructed at the wavelengths used, and the interaction between the photosensitive material and electromagnetic radiation occurs only at the focal point. The principle of multiphoton absorption is described, for example, by 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 tunable wavelengths. In particular, this is a continuous laser or pulsed laser having pulse lengths in the nanosecond, picosecond, or femtosecond range. Pulsed femtosecond lasers have the advantage of requiring a low average power for multiphoton absorption.

[0037] A photosensitive material is any material that is fluid or solid under construction conditions and changes to a second state through multiphoton absorption at a focal volume, for example, through polymerization. The material change must be limited to the focal volume and its immediate vicinity. The change in material properties can be permanent, for example, consisting of a change from a liquid to a solid state, or it can be merely temporary. Furthermore, the permanent change may be reversible or irreversible. The change in material properties does not necessarily have to be a complete transition from one state to the other, but can also be a mixture of both states.

[0038] A second aspect of the present invention provides a device for lithography-based generative manufacturing of three-dimensional parts, particularly for carrying out the method according to the first aspect of the present invention, the device comprising a material support for a solidifiable material and an irradiation device that can be controlled for position-selective irradiation of the solidifiable material using at least one beam, the irradiation device comprising a beam splitter for splitting an input beam into a plurality of beams, a deflection unit positioned upstream or downstream of the beam splitter in the beam path, and an optical imaging unit positioned downstream of the deflection unit and beam splitter to sequentially focus each beam to a focal point in the material, thereby allowing each volume element of the material located at the focal point to be solidified by multiphoton absorption. The device is characterized in that a spatial light modulator having a plurality of electronically controllable pixels is positioned between the imaging unit on one side and the beam splitter and deflection unit on the other side, the plurality of electronically controllable pixels can be scanned by a 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-IYA or MS-304-YIY from HOLO / OR Ltd.

[0040] For example, acousto-optic modulators, resonant scanners, polygon scanners, galvanometer scanners, or combinations thereof can be used as deflection units.

[0041] The beam splitter can be positioned either in front of or behind the deflection unit. Given the limited angular tolerance of the beam splitter, positioning the beam splitter behind the deflection unit is only an option when the maximum deflection angle is relatively small. For larger deflection angles, it is preferable to position the deflection unit behind the beam splitter.

[0042] In a preferred configuration, the spatial light modulator comprises a one-dimensional array of pixels. In particular, the spatial light modulator may include a dynamically adjustable diffraction grating. As already described with respect to a first aspect of the present invention, a so-called line modulator may be used here. The line modulator can change the state of individual pixels at a frequency of at least 300 MHz, thereby enabling extremely high scanning speeds and, consequently, extremely high writing speeds.

[0043] The deflection unit may preferably comprise at least one acousto-optic modulator, which may be positioned in front of the deflection unit. An acousto-optic modulator is an optical component that influences the frequency, propagation direction, and / or intensity of 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 by 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] A further preferred configuration provides that the spatial light modulator comprises a two-dimensional array of pixels. In this regard, the spatial light modulator may be designed, for example, as a reflective liquid crystal microdisplay. Such an LCoS device has a frame rate greater 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. In the case of a layered structure of the component, assuming that the time required to change layers is not taken into account, at least 60 volume elements per second can be generated within the material.

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

[0046] In another preferred embodiment, a polarizing beam splitter is directed to a spatial light modulator, through which multiple beams are directed to the spatial light modulator, and the polarizing beam splitter redirects the beams reflected by the spatial light modulator to an optical imaging unit.

[0047] Beam polarization is preferably achieved by placing a waveplate, particularly a λ / 2 or λ / 4 plate, between the polarizing beam splitter and the spatial light modulator. This involves rotating the beam polarization, resulting in a 90° overall change in the polarizing beam splitter.

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

[0049] Preferably, the illumination device is designed to construct a component layer by layer with layers extending in the xy plane, and the change from one layer to the next involves a change in the relative position of the optical imaging unit with respect to the component in the z direction perpendicular to the xy plane.

[0050] Furthermore, it may be provided that the material is located on a material support such as inside a tank, and that the irradiation of the material is performed from below through a material support that is at least partially transparent to radiation.

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

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

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

[0054] [Figure 1] This is a schematic diagram of a first embodiment of the device according to the present invention. [Figure 2] This is a schematic diagram of a second embodiment of the device according to the present invention. [Figure 3] This figure shows the modified configurations of the first and second embodiments. [Figure 4] This is a schematic diagram of the pixel scanning of a spatial light modulator. [Figure 5] Figure 4 shows the revised configuration. [Figure 6] Figure 4 shows the further modified configuration. [Modes for carrying out the invention]

[0055] In Figure 1, a support is labeled 1, and components are constructed on this support. Support 1 is coated with a photopolymerizable material 2, and a laser beam is focused onto this photopolymerizable material 2, so that each laser beam is successively focused to a focal point in the photopolymerizable material, and the volume element of the material located at the focal point is solidified by multiphoton 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 equipped with two acousto-optic modulators 6 to move back and forth. The zero-order beam is collected by a beam trap 7. The primary beam is guided via a relay system 8 to a beam splitter 9, which splits the beam into multiple beams, and these beams are guided via a scanning lens 17 to a polarizing beam splitter 10. The polarizing beam splitter is designed to transmit multiple beams in the direction of a spatial light modulator 11. The beam passes through the waveplate 12, which delays the polarization component relatively by, for example, λ / 4. The polarization of the beam reflected by the spatial light modulator 11 is rotated again at the waveplate 12 so that when the beam strikes the polarizing beam splitter 10, it is deflected towards the optical imaging unit 13. The beam reaches the optical imaging unit 13 via the tube lens 14. The optical imaging unit 13 includes an objective lens that focuses the laser beam within the writing area onto the material 2.

[0056] In the configuration shown in Figure 1, the spatial light modulator 11 is designed as a line modulator and comprises multiple 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, so that each beam is reflected by the polarizing beam splitter 10 only when it is ON, and then guided to the optical imaging unit 13.

[0057] The beam splitter 9 is configured to generate multiple beams distributed along the pixel row, and the deflection unit 5 is configured to displace the multiple beams together along the pixel row, i.e., to scan the pixel row. Depending on whether each pixel is in the ON or 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 rows and generating corresponding solidified volume elements in material 2 arranged in rows, for example, extending in the y-direction, the support 1 is placed on an XY table displaceable in the x-direction relative to the optical imaging unit 13, thereby changing to the next row. In this way, volume elements can be generated in multiple lines. This is schematically shown in Figure 4.

[0059] Figure 4 shows, for example, a row 23 of pixels 24 extending in the x-direction. In this example, a beam splitter generates two beams 25 positioned at a distance of six pixels from each other. A deflection device scans the pixel row 23 by moving this group of two beams 25 according to arrow 26. Volume elements are solidified at points represented by dark pixels. This is achieved by switching these pixels on in the optical modulator. After scanning the row 23, the support 1 is shifted by one unit in the y-direction, allowing additional volume elements to be solidified in addition to the previously solidified volume elements, as indicated by arrow 29. As the pixel row is scanned, other pixels are switched on, generating the pattern shown in Figure 4 through several lines.

[0060] To construct the component layer by layer, volume elements are solidified one layer at a time in material 2. To construct the first layer, the laser beam is successively focused to a focal point located at the focal plane of the optical imaging unit 13 within material 2. To change to the next plane, the optical imaging unit 13 mounted on the support 15 is moved in the z-direction relative to the support 1 by the interlayer distance. Alternatively, the support 1 can be adjusted relative to the fixed optical imaging unit 13.

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

[0062] In the configuration shown in Figure 2, the spatial light modulator 11 differs from the configuration shown in Figure 1 in that it features a two-dimensional pixel grid. Therefore, a deflection unit 19 is provided that can deflect multiple beams generated by the beam splitter 9 around two vertical axes. For this purpose, the deflection unit 19 comprises a first scanner 20 and a second scanner 21, where the first scanner scans the pixel rows (in the x-direction) as described with respect to the configuration in Figure 1, and the second scanner is controlled to deflect the beam laterally (in the y-direction) from one row to the next. A further difference from the configuration in Figure 1 is that the deflection unit 19 is located behind the beam splitter 9. Furthermore, an acousto-optic modulator 18 is located in front of the beam splitter 9, which sets a global power limit to prevent damage to the modulator and also limits the power at the scanner's turning points.

[0063] By using a spatial light modulator 11 of a two-dimensional pixel array, volumetric elements can be generated within the two-dimensional writing area of ​​the optical imaging unit 13. If the generated components are larger in the x and / or y directions than the writing area of ​​the optical imaging unit 13, substructures of the components are constructed so that they are adjacent to each other (so-called stitching). For this purpose, the support 1 is placed on an XY table, and the XY table can be moved in the x and / or y directions relative to the optical imaging unit 13.

[0064] The configuration shown in Figure 3 differs from the configuration shown in Figure 2 in that, if the function of the optical modulator 11 can be omitted, the mirror 22 can be moved to the beam path instead of the spatial optical modulator 11.

[0065] Raster scanning of the two-dimensional pixel grid of the spatial modulator is shown in Figures 5 and 6. Here, individual pixels are also labeled 24, and it can be seen that the pixels 24 are arranged in multiple lines, i.e., in a two-dimensional array. In the embodiment shown in Figure 5, a beam splitter generates four beams 25 in a rectangular arrangement, so that each beam is moved two-dimensionally across the pixel grid along a path labeled 28 by a deflection device. For example, an acousto-optic deflector deflects the beam in the direction of the double-headed arrow 26 (x-direction), and for example, a galvanometer scanner deflects the beam in the direction of the double-headed arrow 27 (y-direction). By switching between the on and off states, the pattern shown in Figure 5 is generated, so that the volume element is solidified at the point represented by the dark pixels (on state).

[0066] In the embodiment shown in Figure 6, the beam splitter generates three beams 25 in a linear arrangement, so that each beam is moved two-dimensionally across the pixel grid along a path labeled 28 by a deflection device. For example, a resonant scanner deflects the beam in the direction of the bidirectional arrow 26 (x direction), and for example, a galvanometer scanner deflects the beam in the direction of the bidirectional arrow 27 (y direction).

Claims

1. A method for lithography-based generative manufacturing of a three-dimensional part, 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 into focal points in a material (2) by an optical imaging unit (13), the focal points are displaced by deflection units (5, 19) located upstream of the optical imaging unit (13) in the beam direction, thereby sequentially solidifying volume elements of the material (2) located at each of the focal points by multiphoton absorption, wherein 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 individually switched between at least one on state and an off state depending on the geometry of the part to be realized, so that each of the beams is guided to the imaging unit (13) only in the at least one on state.

2. The method according to claim 1, characterized in that the at least one ON state includes at least a first ON state and a second ON state, the pixel is individually switched between the OFF state and the first ON state and the second ON state, and the first ON state and the second ON state generate different radiant intensities at the focal point.

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

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

5. The method according to claim 1, characterized in that 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 such that the beam collides with the row of pixels at intervals of a plurality of pixels.

6. The method according to claim 5, characterized in that the pixels of the spatial light modulator (11) are arranged in a plurality of parallel rows, and the plurality of beams are deflected about two axes.

7. The method according to claim 6, characterized in that the two axes are perpendicular to each other.

8. The method according to claim 6, characterized in that the beam deflection about the first axis is performed by a polygon scanner or a resonant scanner (21).

9. The method according to claim 6, characterized in that the beam deflection about the second axis is performed by a galvanometer scanner (20).

10. The method according to claim 1, characterized in that the plurality of beams are directed towards the spatial light modulator (11) via a polarizing beam splitter (10), the beams are reflected by the spatial light modulator (11) and collide with the polarizing beam splitter (10) with their polarization changed, and the polarizing beam splitter (10) directs the beams towards the optical imaging unit (13).

11. The method according to claim 1, characterized in that 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 located in the beam path.

12. The method according to claim 1, characterized in that the component is constructed layer by layer by layer extending in the x-y plane, and the change from one layer to the next layer 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.

13. A device for lithography-based generative manufacturing of three-dimensional parts, particularly for carrying out the method of claim 1, the device comprising: a material support (1) for a solidifiable material (2); and an irradiation device that can be controlled for position-selective irradiation of the solidifiable material using at least one beam, wherein the irradiation device comprises: a beam splitter (9) for splitting an input beam into a plurality of beams; deflection units (5, 19) positioned upstream or downstream of the beam splitter (9) in the beam path; and a device positioned downstream of the deflection units (5, 19) and the beam splitter (9) for sequentially focusing each beam to a focal point in the material (2), thereby A device comprising an optical imaging unit (13) in which volume elements of the material (2) located at each of the aforementioned focal points can be solidified by multiphoton absorption, wherein a spatial light modulator (11) having a plurality of electronically controllable pixels is disposed between the imaging unit (13) on one side and the beam splitter (9) and the deflection units (5, 19) on the other side, 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 of the beams is guided to the imaging unit (13) only in the at least one on state.

14. The device according to claim 13, wherein the at least one ON state includes at least a first ON state and a second ON state, the pixel is individually switchable between the OFF state and the first ON state and the second ON state, and the first ON state and the second ON state generate different radiant intensities at the focal point.

15. The device according to claim 13, characterized in that the preceding spatial light modulator (11) comprises a one-dimensional array of pixels.

16. The device according to claim 13, characterized in that the spatial light modulator (11) comprises a dynamically adjustable diffraction grating.

17. The device according to claim 13, characterized in that the deflection unit (5) comprises at least one acousto-optic modulator.

18. The device according to claim 13, characterized in that the spatial light modulator (11) comprises a two-dimensional array of pixels.

19. The device according to claim 18, characterized in that the spatial light modulator (11) is designed as a reflective liquid crystal microdisplay.

20. The device according to claim 18, characterized in that the deflection unit (19) is designed as a two-axis deflection unit.

21. The device according to claim 20, characterized in that the deflection unit (19) comprises 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.

22. The device according to claim 13, characterized in that a polarizing beam splitter (10) is assigned to the spatial light modulator (11), the plurality of beams are directed to the spatial light modulator (11) through the polarizing beam splitter (10), and the polarizing beam splitter (10) deflects the beams reflected by the spatial light modulator (11) to the optical imaging unit (13).

23. The device according to claim 22, characterized in that a waveplate (12), particularly a λ / 2 plate or a λ / 4 plate, is arranged between the polarizing beam splitter (10) and the spatial light modulator (11).

24. The device according to claim 13, characterized in that a mirror (22) is provided, and the spatial light modulator (11) and the mirror (22) can be displaced so that either the spatial light modulator (11) or the mirror (22) can be moved to an operating position located in the beam path.

25. The device according to claim 13, wherein the irradiation device is designed to construct the component layer by layer by layers extending in the x-y plane, and the change from one layer to the next layer 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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