Method and device for lithography-based additive manufacturing of a component

Abstract

The invention relates to a method for the lithography-based additive manufacturing of a three-dimensional component, in which a beam emitted by an electromagnetic radiation source (3) is focused onto a focal point within a material (2) by means of an optical imaging unit (12) in order to introduce an exposure dose into the material (2), and the focal point is shifted by means of a deflection system positioned upstream of the imaging unit (12) in the beam path, and a volume element of the material (2) located at the focal point is solidified by means of multiphoton absorption, wherein the shifting of the focal point comprises a first movement component (18), namely an in particular continuous shifting along a main path, onto which a second movement component (21), namely a repeated transverse movement running transversely to the first movement component, is superimposed, and the exposure dose is modulated during the transverse movement.

Description

[0001] Method and apparatus for lithography-based additive manufacturing of a component

[0002] The invention relates to a method and a device for lithography-based additive manufacturing of a three-dimensional component.

[0003] A method for forming a component in which the solidification of a photosensitive material is carried out by means of multiphoton absorption is known, for example, from DE 10111422 Al. For this purpose, a focused laser beam is shone into the bath of photosensitive material, whereby the irradiation conditions for a multiphoton absorption process that triggers solidification are only met in the immediate vicinity of the focus, so that the focus of the beam is guided within the bath volume to the areas to be solidified according to the geometric data of the component to be produced.

[0004] At each focal point, a volume element of the material is hardened, whereby adjacent volume elements adhere to one another, and the component is built up by successively hardening adjacent volume elements. The component can be built up layer by layer, i.e., volume elements of a first layer are hardened before volume elements of the next layer are hardened.

[0005] Irradiation devices for multiphoton absorption processes comprise optics for focusing a laser beam and a deflection device for deflecting the laser beam. The deflection device is designed to focus the beam successively onto focal points within the material that lie in the same plane, preferably perpendicular to the beam's direction of incidence into the material. In an x, y, z coordinate system, this plane is also referred to as the x, y plane. The solidified volume elements created by the beam deflection in the x, y plane form a layer of the component. To enable continuous operation of the deflection device, the beam is interrupted, or switched off and on again, between the solidification of two successive volume elements.

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

[0007] Structuring a suitable material using multiphoton absorption offers the advantage of extremely high structural resolution, enabling the creation of volume elements with minimum feature sizes of up to 50 nm x 50 nm x 50 nm. However, due to the small focal point volume, the throughput of such a method is very low, as, for example, for a volume of 1 mm 3 more than 10 in total 9Points must be exposed. This leads to very long build times, which is the main reason for the limited industrial use of multiphoton absorption methods. To increase component throughput without sacrificing the possibility of high structural resolution, it has already been proposed to vary the volume of the focal point during component buildup, so that the component is built from solidified volume elements of different volumes. Due to the variable volume of the focal point, high resolutions are possible (with a small focal point volume). At the same time, a high writing speed (measured in mm) is possible (with a large focal point volume). 3 / h) achievable. By varying the focal point volume, high resolution can be combined with high throughput. For example, varying the focal point volume can be used by employing a large focal point volume inside the component being built to increase throughput, while using a smaller focal point volume on the component's surface to create a high-resolution surface. Increasing the focal point volume allows for higher structuring throughput because it increases the volume of material solidified in a single exposure. To maintain high resolution at high throughput, small focal point volumes can be used for finer structures and surfaces, and larger focal point volumes for coarser structures and / or for filling interior spaces. Methods and devices for changing the focal point volume are described in WO 2018 / 006108 A1.

[0008] Another way to increase the writing speed is to split the writing beam into a plurality of beams using a beam splitter, each focused into the material to be solidified, thus enabling the parallel solidification of multiple volume elements (Kelemen et al: “Parallel photopolymerisation with complex light patterns generated by diffractive optical elements”, Optics Express, Vol. 15, No. 22, pp. 14488–14497). However, the individual writing beams cannot be positioned independently of each other, so only a plurality of identical components corresponding to the number of beams can be produced.

[0009] In the field of stereolithography, it is known from US 5,536,467 to control a plurality of writing beams independently of one another, with each writing beam being deflected by its own mirror to the corresponding position in the material to be solidified. However, a disadvantage is that the deflection device includes mechanically actuated mirrors, thus limiting the scanning speed, and that the depicted device is not suitable for solidifying volume elements using multiphoton absorption. Furthermore, the complexity of the equipment increases proportionally to the number of writing beams to be moved independently.

[0010] Furthermore, it is known from WO 2018 / 206161 Al to modulate the exposure dose of a writing beam during its movement in such a way that a plurality of volume elements are solidified along the direction of movement of the writing beam, whereby by varying the exposure dose, e.g. with the aid of an acousto-optic modulator, the size or volume of the solidified volume element can be adjusted in order to improve the approximation to the desired external geometry in the edge regions of the component to be manufactured (so-called "gray scaling"). The invention aims to further develop a method and a device for lithography-based additive manufacturing of a three-dimensional component in such a way that the writing speed (measured in mm) 3 / h) without restricting the component geometry and with minimal equipment effort, it is increased even further.

[0011] To solve this problem, a first aspect of the invention provides a method for lithography-based additive manufacturing of a three-dimensional component, in which a beam emitted from an electromagnetic radiation source is directed into a material by means of an optical imaging unit in a direction of incidence extending in the z-direction and focused on a focal point within a material in order to introduce an exposure dose into the material, and the focal point is displaced by means of a deflection system arranged upstream of the optical imaging unit in the direction of the beam, and a volume element of the material located at the focal point is solidified by means of multiphoton absorption.The method is characterized in that the displacement of the focal point comprises a first movement component, namely a continuous displacement along a main path, which is superimposed by a second movement component, namely a repeated transverse movement perpendicular to it, and that the exposure dose is modulated during the transverse movement. The first movement component and the second movement component lie, in particular, in an x,y plane perpendicular to the z-direction.

[0012] The lateral movement component can be executed at a significantly higher speed than the movement component along the main path. This is because the lateral movement has a short travel distance and can therefore be superimposed with rapid oscillations, whereas the movement along the main path is designed to scan the largest possible area. The speed of the lateral movement component can be at least twice, preferably at least four times, and preferably at least ten times the speed of the first movement component.

[0013] By modulating the exposure dose during rapid lateral movement, multiple volume elements can be solidified side by side. This increases the effectively writable width along the main path without reducing the displacement speed of the focal point along the main path. Thus, at a constant scan speed, a wider area of ​​the material can be structured in parallel, which increases the writing speed (in mm). 3 / h) significantly increased. For example, this allows several parallel lines extending in the direction of the first motion component to be written in a single pass. By appropriately controlling the modulation of the exposure dose, the arrangement of the volume elements can be chosen arbitrarily. In the case of generating multiple parallel lines, for example, the line spacing can be freely selected. This allows switching between a fine writing mode, in which the volume elements or lines are close together, and a coarse writing mode, in which the volume elements or lines are further apart.

[0014] The modulation of the exposure dose during the transverse movement can be performed very rapidly, i.e., at a high clock frequency, using suitable optical devices such as acousto-optic modulators. Preferably, the clock frequency can be 30 MHz or higher, meaning the exposure dose can be varied 30 million times or more per second. This allows the exposure intervals to be precisely controlled and adapted to the high speed of the transverse movement. This enables the exact positioning of the solidified volume elements and contributes to improved structural quality.

[0015] Compared to approaches requiring multiple independently movable writing beams, the present invention is characterized by minimal additional equipment requirements. Only one additional transverse movement component and one modulation unit for the exposure dose are needed. This reduces the complexity and cost of the overall system without compromising performance or requiring a significant increase in the power of the radiation source.

[0016] The invention provides that the repeated transverse movements can be either aligned in the same direction or designed as a repeated back-and-forth movement. In the first case, the transverse movement always occurs in the same direction, for example, perpendicular to the main path, causing the beam to move along a multitude of parallel lines running obliquely to the main path. In the second case, the transverse movement is executed as an oscillating back-and-forth movement, so that the focal point moves alternately in opposite directions perpendicular to the main path. The superposition of the first movement component along the main path with the second movement component of the back-and-forth movement results in a zigzag motion of the beam. The angle at which the lines run to the main path can be adjusted by the ratio of the velocities of the two movement components to each other.The faster the lateral movement is chosen compared to the speed of the first movement component, the steeper the lines along which the beam is guided. By adjusting the speed ratio, not only the orientation of the lines but also the distance of the lines or volume elements measured in the direction of the main path can be precisely controlled.

[0017] The orientation of the lines along which the beam is guided can also be adjusted by the direction of the transverse motion component. Preferably, the transverse motion component extends at a right angle to the direction of the main path. Alternatively, the transverse motion component can be oriented at an acute angle to the direction of the main path. Here, the transverse motion component can be directed backward or forward relative to the direction of the main path. In the case of a backward-directed transverse motion component, the acute angle between the direction of the main path and the transverse motion component, and the relative speed of the two motion components, can be coordinated such that the resulting displacement of the beam follows parallel transverse lines that are perpendicular to the main path.

[0018] A preferred embodiment of the invention provides for varying the amplitude of the transverse motion component. By changing the amplitude, the width of the area solidified during a scan along the main path can be dynamically adjusted. Increasing the amplitude results in wider coverage of the material perpendicular to the main path, while decreasing the amplitude allows for a narrower solidification zone. By selectively adjusting the amplitude during the writing process, areas of varying widths can be structured with a single scan. The amplitude can also be reduced to zero, if required, to generate a series of volume elements arranged along the main path in a conventional manner.

[0019] A further preferred embodiment of the invention consists in generating the lateral motion by deflecting the beam using at least one acousto-optic deflector. Acousto-optic deflectors are based on the principle of light diffraction at periodic structures generated by acoustic waves in an optical medium. Applying a high-frequency alternating voltage to a transducer generates a sound wave in the optical medium, resulting in a periodic variation of the refractive index. The incident light beam is diffracted at this grating structure and deflected depending on the frequency and amplitude of the acoustic wave. Acousto-optic deflectors are characterized by very high scanning speeds and precision, making them ideally suited for generating rapid lateral motion.In contrast, the motion component along the main path can preferably be generated using a galvanometer scanner. Galvanometer scanners use movable mirrors that can be precisely deflected via galvanometer drives to guide the beam along the main path.

[0020] When a light beam is deflected by an acousto-optic deflector, a velocity-dependent divergence can occur. This can preferably be reduced by converging the beam immediately in front of the acousto-optic deflector in such a way that any divergence of the beam caused by the acousto-optic deflector is at least partially, or essentially completely, compensated.

[0021] Acousto-optic deflectors are known as longitudinal wave AODs and transverse wave AODs. Preferably, at least one longitudinal wave AOD is used within the scope of the invention, i.e., an acoustic longitudinal wave is generated in the acousto-optic deflector. It has been shown that while the maximum deflection angle is generally smaller for longitudinal wave AODs than for transverse wave AODs, the speed of sound is higher for longitudinal wave AODs, as is the case, for example, with AODs made of tellurium dioxide (TeO2), resulting in a higher deflection or scan speed.

[0022] A further preferred embodiment of the invention provides for generating the lateral motion by deflecting the beam using two acousto-optic deflectors arranged one behind the other in the beam path. The deflection directions of the two deflectors are aligned at an angle to each other, preferably a right angle. The resulting lateral motion component of the beam then results from the vector sum of the two individual deflections. By combining the deflection effects, the speed and amplitude of the lateral motion can be significantly increased compared to using a single deflector, so that wider areas can be covered with a single scan. Within the scope of the invention, the modulation of the

[0023] Exposure dose can be used to achieve different effects. On the one hand, the exposure dose can be adjusted so that the transverse spacing between successively formed volume elements is varied. To achieve this, the exposure dose, e.g., the radiation intensity, can preferably be changed in pulses between a high and a low value. By varying the duty cycle, i.e., the ratio between the duration of the high value and the total period, the number of volume elements per unit volume in the component can be precisely controlled. At a low value, the exposure dose at the focal point is insufficient to trigger polymerization of the material through two- or multi-photon absorption. The low value can be chosen so that essentially no radiation penetrates the material.By appropriately selecting the duty cycle, areas with different densities of volume elements can be created, which allows for an adjustment of the component properties.

[0024] On the other hand, the exposure dose can also be modulated in such a way that volume elements of different sizes are formed during the transverse movement. By varying the radiation intensity and / or the exposure time at different positions along the transverse movement, volume elements of different sizes can be selectively generated. This technique enables the realization of a grayscale effect within the solidified structure. By generating volume elements with graduated sizes, fine detail structures and material gradients can be realized in the component. This advanced training thus opens up new possibilities for the production of components with locally adapted properties and high resolution of structural details.

[0025] Compared to conventional grayscaling methods, the invention makes it possible to extend grayscaling to multiple lines due to the superimposed transverse movement.

[0026] The two types of modulation of the sealing dose can be combined to form a plurality of volume elements during the transverse movement and to adjust their respective volumes at the same time.

[0027] Due to the possibility of independently adjusting the printing parameters, namely the number of volume elements per unit volume, the size of the volume elements, and the arrangement of the volume elements along the transverse direction of movement (i.e., the line spacing), the inventive method can maintain a substantially square geometry of the volume elements in the xy-plane even when one of the aforementioned parameters is changed, without affecting the writing speed in mm. 3 / h to reduce. With conventional methods without superimposing a transverse movement, the pixel density in the writing direction can be increased, which reduces the extent of the volume elements in the writing direction due to the overlap of successive volume elements. However, the width of the volume elements remains the same, so a square geometry is not achieved. A square geometry could be achieved by adjusting the line spacing and reducing the radiation intensity, but this would decrease the writing speed.

[0028] The exposure dose introduced into the material at the focal point can be modified by various means. A particularly advantageous embodiment of the invention consists of modulating the exposure dose by changing the radiation intensity of the beam. For this purpose, an acousto-optic modulator is preferably used, which enables precise and rapid adjustment of the intensity. Acousto-optic modulators are based on the principle of the diffraction of light by an acoustic wave, which is generated by a sound transducer in an optical medium. By applying a high-frequency electrical signal to the sound transducer, a sound wave is generated, which leads to a periodic variation of the refractive index. By changing the amplitude of the electrical signal, the intensity of the light beam and thus the exposure dose can be precisely modulated.Acousto-optic modulators are characterized by very high switching speeds.

[0029] Alternatively or additionally, the exposure dose can be adjusted, for example, by changing the exposure time, thus controlling the dwell time of the focus point accordingly. A longer exposure time results in a higher dose, while a shorter exposure time reduces the dose.

[0030] A further advantageous embodiment of the invention provides for selectively changing the beam diameter along the beam path to optimize the system's performance. In particular, the beam diameter can be chosen to be smaller when passing through the acousto-optic modulator (AOM) than when passing through the acousto-optic deflector (AOD) used to generate the transverse motion. This adjustment of the beam diameter has a positive effect on the switching frequency and the response time of the AOM. A smaller beam diameter in the AOM means that the sound wave has to travel a shorter distance to completely traverse the beam. This reduces the time the AOM needs to modulate the beam. A shorter interaction time, in turn, allows for a higher switching frequency, so that the beam intensity can be adjusted more quickly and precisely.In contrast, the beam diameter can be larger when passing through the AOD, as the switching speed requirements are less critical here. Adjusting the beam diameter can be achieved by using beam widening or beam shaping optics, or by a lens positioned in the beam path between the AOM and the AOD.

[0031] Preferably, the component is built up layer by layer with layers extending in an x-y plane, wherein the transition from one layer to the next involves a change in the relative position of the optical imaging unit relative to the component in a z-direction perpendicular to the xy-plane. The z-direction here essentially corresponds to the direction of incidence of the beam.

[0032] A preferred method arises when the material is placed on a material support, such as in a tray, and the material is irradiated from below through the material support, which is at least partially permeable to radiation. 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 also possible to irradiate the material from above.

[0033] The principle of multiphoton absorption is used within the scope of the invention to initiate a photochemical process in the photosensitive material bath. Multiphoton absorption methods also include, for example, two-photon absorption methods. As a result of the photochemical reaction, the material changes into at least one other state, typically undergoing photopolymerization. The principle of multiphoton absorption is based on the fact that the aforementioned photochemical process only takes place in those regions of the beam path where a photon density sufficient for multiphoton absorption is present. The highest photon density occurs at the focal point of the optical imaging system, so that multiphoton absorption is only likely to occur at the focal point.Outside the focal point, the photon density is lower, so the probability of multiphoton absorption outside the focal point is too low to cause an irreversible change in the material through a photochemical reaction. The electromagnetic radiation can pass through the material largely unimpeded at the wavelength used, and interaction between the photosensitive material and the electromagnetic radiation only occurs at the focal point. The principle of multiphoton absorption is described, for example, in Zipfel et al., “Nonlinear magic: multiphoton microscopy in the biology”, Nature Biotechnology Volume 21, Number 11, November 2003.

[0034] The electromagnetic radiation source can preferably be a collimated laser beam. The laser can emit one or more fixed or variable wavelengths. In particular, it is a continuous or pulsed laser with pulse durations in the nanosecond, picosecond, or femtosecond range. A pulsed femtosecond laser offers the advantage that a lower average power is required for multiphoton absorption.

[0035] Photosensitive material is defined as any material that, under normal conditions, is fluid or solid and undergoes a transition to a second state through multiphoton absorption within the focal point volume—for example, through polymerization. The material change must be confined to the focal point volume and its immediate surroundings. The change in the substance's properties can be permanent, such as a change from a liquid to a solid state, or it can be temporary. Furthermore, a permanent change can 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 occur as a mixture of both states.

[0036] The beam can be split into at least two beams by means of a beam splitter, which are displaced in parallel according to the invention, i.e., that the displacement each comprises a first movement component, namely a particularly continuous displacement along a main path, which is superimposed by a second movement component, namely a repeated transverse movement running perpendicular to it. The exposure dose is modulated during the transverse movement. The modulation of the exposure dose can preferably be carried out for the two or more beams together or for each of the two or more beams independently of the other beams. In the latter case, parallel writing with an independent arrangement of the volume elements is achieved.

[0037] According to a second aspect, the invention provides a device for lithography-based additive manufacturing of a three-dimensional component, which is particularly suitable for carrying out a method according to the first aspect of the invention.The device comprises a material carrier for a solidifiable material and an irradiation device which can be controlled for the location-selective irradiation of the solidifiable material with at least one beam, wherein the irradiation device comprises a deflection system and an optical imaging unit downstream of the deflection system, with which the beam can be directed into a material in a z-direction and focused on a focal point within the material in order to introduce an additional radiation dose into the material, and the focal point can be moved by means of the deflection system, whereby each volume element of the material located at the focal point can be solidified by means of multiphoton absorption.According to the invention, the deflection system comprises a first deflection module for generating a first movement component and a second deflection module for generating a second movement component of the displacement of the focal point, wherein the first movement component is, in particular, a continuous displacement along a main path, and the second movement component is a repeated transverse movement perpendicular to it, and means for modulating the exposure dose during the transverse movement are provided. The first movement component and the second movement component lie, in particular, in an x,y plane perpendicular to the z-direction.

[0038] As already mentioned in connection with the method according to the invention, the means for modulating the exposure dose can preferably be configured to change the radiation intensity of the beam and, in particular, may include an acousto-optic modulator. The means for modulating the exposure dose, in particular the acousto-optic modulator, can be controlled by a control unit.

[0039] The control unit can be configured to modulate the exposure dose in such a way that a plurality of volume elements are formed during the transverse movement.

[0040] The control unit can also be configured to modulate the exposure dose in such a way that the distance between successively formed volume elements is varied.

[0041] The control unit can also be configured to modulate the exposure dose such that the volume elements are arranged along parallel lines that run parallel to the main path. The control unit can also be configured to modulate the exposure dose such that volume elements of different volumes are formed during the transverse movement.

[0042] The control unit can preferably be configured to change the radiation intensity in a pulsed manner between a high and a low value, wherein the duty cycle is variable to change the number of volume elements per unit volume in the component.

[0043] The control unit can preferably be designed to change the radiation intensity in a pulsed manner between a high and a low value in order to arrange volume elements in a location-selective manner according to the geometry of the component to be achieved.

[0044] The second deflection module preferably has an acousto-optic deflector which can be controlled by its own control unit or by the same control unit as the acousto-optic modulator.

[0045] The control unit can be configured to execute the lateral movement as a repeated back-and-forth motion and / or to vary the amplitude of the lateral movement, in particular the back-and-forth motion.

[0046] The control unit(s) of the acousto-optic modulator and the acousto-optic deflector can be configured to match the velocity of the transverse motion component relative to the velocity of the first motion component in the direction of the main path, to adjust the angle of the resulting displacement relative to the main path, and / or to adjust the distance between successive transverse sections of the resulting displacement measured in the direction of the main path.

[0047] The invention is explained in more detail below with reference to an exemplary embodiment shown schematically in the drawing. In this drawing, Fig. 1 shows a schematic representation of an embodiment of the device according to the invention and Fig. 2 shows a schematic representation of the displacement of the focal point and the arrangement of volume elements.

[0048] Figure 1 shows a support 1 on which a component is to be built. The support 1 is coated with a photopolymerizable material 2, into which a laser beam is focused. The laser beam is successively focused onto focal points within the photopolymerizable material, thereby solidifying a volume element of the material located at each focal point 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, after a reduction in beam diameter by the optical element 5, modulated by an acousto-optic modulator 6 to change the radiation intensity. After beam expansion by the optical element 7, the beam is guided through an acousto-optic deflector 8, which deflects the beam to execute a transverse motion component.The zero-order beam is captured in a beam trap 9. The first-order beam is guided via a relay system 10 to a deflecting mirror 11, which deflects the beam towards the optical imaging unit 12. The beams reach the optical imaging unit 12 via a deflection unit 13, which shifts the focal point along the skin path component and comprises a first galvanometer scanner 14 and a second galvanometer scanner 15, whose deflection directions are at right angles to each other. The optical imaging unit 12 includes a lens that focuses the beam within a writing area and directs it into the material 2. The first galvanometer scanner 14 deflects the beam so that the beam is shifted in an x-plane along the main path, and the second galvanometer scanner 15 deflects the beam so that the beam is shifted in a y-direction along the main path.The x and y directions span an xy-plane that runs perpendicular to the z-direction, which essentially corresponds to the direction of incidence of the beam into material 2.

[0049] By shifting the focal point in the xy-plane, volume elements can be generated within a two-dimensional writing area of ​​the optical imaging unit 12. If the component to be manufactured is larger in the x and / or y direction than the writing area of ​​the optical imaging unit 12, substructures of the component are built up side by side (so-called stitching). For this purpose, the carrier 1 is arranged on a cross table that is movable in the x and / or y direction relative to the optical imaging unit 12.

[0050] To build the component layer by layer, two volume elements of one layer are solidified within the material 2. To build up a first layer, the beam is focused successively onto focal points located within the material 2 in the focal plane of the optical imaging unit 12. To transition to the next layer, the optical imaging unit 12, which is attached to a support 16, is moved in the z-direction relative to the support 1 by the layer spacing. Alternatively, the support 1 can also be moved relative to the stationary optical imaging unit 12.

[0051] Furthermore, a control unit 17 is provided, which controls the deflection unit 13, the acousto-optic deflector 8, the acousto-optic modulator 6, the height adjuster 16 and the cross table 1.

[0052] Fig. 2 schematically illustrates the displacement of the focal point. Fig. 2a shows a conventional procedure in which the focal point is moved, e.g., by a galvanometer scanner, along the main path 18 through the material 2, while an acousto-optic modulator modulates the exposure dose such that a series of volume elements 20, namely volume elements “1”, “2”, “3”, and “4”, are created along a line 19.

[0053] Fig. 2b shows the embodiment according to the invention, in which the motion component along the main path 18 is superimposed by a faster transverse motion component 21, resulting in the displacement of the focal point along the line 22. The right part of Fig. 2b shows the arrangement of the volume elements “1”, “2”, “3”, and “4” along the line 22. After reaching the position for volume element “4”, the transverse motion component of the beam jumps back to the initial position, allowing volume elements “5”, “6”, “7”, and “8” to be created offset parallel to the line 22. In other words, compared to the embodiment according to Fig. 2a, volume elements can be written essentially simultaneously along the parallel lines 23, 24, 25, and 26, thereby increasing the writing area transverse to the main path direction, without having to increase the speed of the main path motion component.

[0054] The radiation intensity can now be modulated in various ways using the acousto-optic modulator. For example, Fig. 2c shows that the radiation intensity is switched between a high and a low value, so that only the volume elements "1", "3", etc., are written, but not the volume elements "2", "4", etc. This makes it possible to vary the density of the lines or the distance between volume elements.

[0055] Fig. 2d shows the geometry of a component 27 to be built up in a cross-section running in the xy-plane. In areas 28 and 29, the procedure according to Fig. 2a was chosen. In area 30, the procedure according to Fig. 2b was chosen. It can be seen that this allows a wide writing area to be achieved while simultaneously adapting to the inclined outer contour of the component 27.

Claims

24 Patent claims:

1. A method for lithography-based additive manufacturing of a three-dimensional component, in which a beam emitted from an electromagnetic radiation source (3) is directed into a material by means of an optical imaging unit (12) in a direction of incidence extending in the z-direction and focused onto a focal point within a material (2) in order to introduce an exposure dose into the material, and the focal point is displaced by means of a deflection system arranged upstream of the optical imaging unit (12) in the direction of the beam, and a volume element of the material (1) located at the focal point is solidified by means of multiphoton absorption, characterized in that the displacement of the focal point comprises a first movement component (18), namely a particularly continuous displacement along a main path, which is decoupled from a second movement component (21), namely a transverse displacement thereto.repeated transverse movement is superimposed, and the exposure dose is modulated during the transverse movement.

2. Method according to claim 1, characterized in that the first motion component (18) and the second motion component (21) lie in an x,y-plane perpendicular to the z-direction.

3. Method according to claim 1 or 2, characterized in that the exposure dose is modulated such that a plurality of volume elements are formed during the transverse movement.

4. Method according to claim 1, 2 or 3, characterized in that the exposure dose is modulated such that the distance in the transverse direction between successively formed volume elements is varied.

5. Method according to one of claims 1 to 4, characterized in that the exposure dose is modulated such that volume elements of different volumes are formed during the transverse movement.

6. Method according to one of claims 1 to 5, characterized in that the exposure dose is modulated by changing the radiation intensity of the beam.

7. Method according to one of claims 1 to 6, characterized in that the radiation intensity is changed by means of an acousto-optic modulator (6).

8. Method according to one of claims 1 to 7, characterized in that the radiation intensity is changed in a pulsed manner between a high and a low value and the duty cycle is varied to change the number of volume elements per unit volume in the component.

9. Method according to one of claims 1 to 8, characterized in that the transverse movement is designed as a repeated back-and-forth movement.

10. Method according to one of claims 1 to 9, characterized in that the amplitude of the transverse movement, in particular the back-and-forth movement, is varied.

11. Method according to any one of claims 1 to 10, characterized in that the transverse movement is achieved by deflecting the beam is generated by means of at least one acousto-optic deflector (8).

12. Method according to claim 11, characterized in that the beam is converged immediately in front of the acousto-optic deflector (8) in such a way that a divergence of the beam caused by the acousto-optic deflector (8) is at least partially, substantially completely, compensated.

13. Method according to claim 11 or 12, characterized in that an acoustic longitudinal wave is generated in the acousto-optic deflector (8).

14. Method according to claim 11, 12 or 13, characterized in that the transverse movement is generated by deflecting the beam by means of two acousto-optic deflectors (8) arranged one behind the other in the beam path, the deflection directions of which are preferably at a right angle to each other.

15. Method according to one of claims 11 to 14, characterized in that the beam diameter is changed along the beam path, such that the beam diameter is smaller when passing through the acousto-optic modulator (6) than when passing through the acousto-optic deflector (8).

16. Device for lithography-based additive manufacturing of a three-dimensional component, in particular for carrying out a method according to one of claims 1 to 15, comprising a material carrier (1) for a solidifiable material (2) and an irradiation device for 27. The irradiation of the solidifiable material can be selectively controlled with at least one beam, wherein the irradiation device includes a deflection system and a beam The deflection system comprises a downstream optical imaging unit (12) with which the beam can be directed into a material in a z-direction and focused onto a focal point within the material (2) in order to introduce an additional exposure dose into the material (2), and the focal point can be displaced by means of the deflection system, whereby a volume element of the material (2) located at the focal point can be solidified by means of multiphoton absorption, characterized in that the deflection system comprises a first deflection module (13) for generating a first movement component (18) and a second deflection module (8) for generating a second movement component (21) of the displacement of the focal point, wherein the first movement component (18) is a particularly continuous displacement along a main path, and the second movement component (21) is a repeated transverse movement perpendicular to it.and that means are provided for modulating the exposure dose during the transverse movement.

17. Device according to claim 16, characterized in that the first motion component (18) and the second motion component (21) lie in an x,y plane perpendicular to the z-direction.

18. Device according to claim 16 or 17, characterized by a control unit for controlling the means for modulating the exposure dose, wherein the control unit is configured to modulate the exposure dose in such a way as to 28 modulate such that a plurality of volume elements are formed during the transverse movement.

19. Device according to claim 16, 17 or 18, characterized by a control unit for controlling the means for modulating the exposure dose, wherein the control unit is configured to modulate the exposure dose in such a way that the distance between successively formed volume elements is varied.

20. Device according to one of claims 16 to 19, characterized in that the exposure dose is modulated such that volume elements of different volumes are formed during the transverse movement.

21. Device according to one of claims 16 to 20, characterized in that the means for modulating the exposure dose are designed to change the radiation intensity of the beam.

22. Device according to one of claims 16 to 21, characterized in that the means for modulating the exposure dose comprise an acousto-optic modulator ( 6 ).

23. Device according to one of claims 16 to 22, characterized in that a control unit (17) is provided for controlling the acousto-optic modulator (6), which is configured to change the radiation intensity pulse-wise between a high and a low value, wherein the duty cycle is variable to change the number of volume elements per unit volume in the component. 29 24. Device according to one of claims 16 to 23, characterized in that the second deflection module (8) is designed to perform the transverse movement as a repeated back-and-forth movement.

25. Device according to one of claims 16 to 24, characterized in that the second deflection module (8) is designed to vary the amplitude of the transverse movement, in particular the back-and-forth movement.

26. Device according to one of claims 16 to 25, characterized in that the second deflection module (8) has at least one acousto-optic deflector.

27. Device according to claim 26, characterized in that the second deflection module (8) has two acousto-optic deflectors arranged one behind the other in the beam path, the deflection directions of which are preferably at a right angle to each other.

28. Device according to claim 26 or 27, characterized in that at least one optical device for changing the beam diameter is arranged in the beam path, such that the beam diameter is smaller when passing through the acousto-optic modulator (6) than when passing through the acousto-optic deflector (8).

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