Volumetric 3D printing apparatus for forming three-dimensional objects

Abstract

An apparatus (1) for forming volumetric 3D printing of a three-dimensional object, the apparatus comprising: a working volume (3) configured to receive a photopolymerizable material, in particular a photopolymerizable polymer resin, to be irradiated by light to form a three-dimensional object; at least one first illumination device (4) configured to illuminate light (L1) of a first wavelength into the working volume to produce at least one first light projection (7) in the working volume, the at least one first light projection comprising a plurality of light beams passing through the working volume in at least one light plane (8); and at least one light modulation device (11) assigned to the at least one first illumination device.

Description

Technical Field

[0001] The present invention relates to a device for volumetric 3D printing for forming a three-dimensional object, the device comprising: a working volume, the working volume being configured to receive a photopolymerizable material, in particular a photopolymerizable polymer resin, which is to be irradiated with light to form a three-dimensional object; and at least one first irradiation device, the first irradiation device being configured to irradiate light of a first wavelength into the working volume to generate at least one first light projection in the working volume, the at least one first light projection comprising a plurality of light beams passing through the working volume in at least one light plane. Background Art

[0002] Apparatuses and related methods for volumetric 3D printing of three-dimensional objects are known. The corresponding apparatus can be configured to perform at least one localized polymerization process of a polymeric material for the continuous additive manufacturing of at least one three-dimensional object, for example, by multiphoton photopolymerization, particularly multi-color photopolymerization, and more particularly bi-color photopolymerization.

[0003] Exemplary principles of so-called volumetric 3D printing devices and associated methods are described in detail, for example, in WO 2020 / 245456 A1, the content of which may be incorporated herein by reference.

[0004] It is well known that three-dimensional objects manufactured using corresponding volumetric 3D printing devices and related methods may have undesirable artifacts and thus undesirable properties. The corresponding artifacts may include artifacts on the surface and / or within the volume of the corresponding three-dimensional object. The corresponding artifacts may include artifacts with (quasi-)regular or irregular stripes or patterns, which make the optical appearance of the manufactured three-dimensional object appear as if it were built up in layers as in traditional additive manufacturing, such as the well-known stereolithography principles and digital light processing principles. Therefore, the corresponding artifacts may particularly impair the optical appearance and related properties of the manufactured three-dimensional object. It is speculated that the corresponding artifacts are caused by at least one of the following factors: local variations in light intensity within a light plane in the working volume, laser speckle effects in the light beam or light plane, positive and / or negative optical interference of light in the light beam or light plane, and shadow formation in the light beam or light plane caused by bubbles, particles, etc. in the working volume.

[0005] Therefore, it is necessary to improve the corresponding 3D printing equipment and related methods according to the characteristics of the manufactured three-dimensional objects.

[0006] It is therefore an object of the present invention to overcome the drawbacks of the known devices and to provide a device for volumetric 3D printing of three-dimensional objects, which device enables the manufacture of three-dimensional objects with improved properties. Summary of the Invention

[0007] A first aspect of the present invention relates to an apparatus for volumetric printing to form at least one three-dimensional object. The corresponding three-dimensional object can be, for example, a technical component or an assembly of technical components. The apparatus is therefore generally configured to perform a volumetric 3D printing process to form one or more three-dimensional objects. The corresponding volumetric 3D printing process can include at least one local polymerization process of a polymerizable material (in particular, a photopolymerizable material) for continuous additive manufacturing of at least one three-dimensional object, in particular, a plurality of three-dimensional objects, by multiphoton photopolymerization (in particular, multi-color photopolymerization, more particularly, two-color photopolymerization). Therefore, the apparatus can be configured to perform one or more local polymerization processes of a polymerizable material, such as a photopolymerizable monomer resin, wherein the polymerizable material can include, but is not limited to, acrylates, methacrylates, thiols + alkenes, epoxides, oxiranes, oxetanes, or vinyl ethers, and / or a photopolymerizable oligomer resin, wherein the polymerizable material can include, but is not limited to, acrylates, methacrylates, thiols + alkenes, epoxides, oxiranes, oxetanes, or vinyl ethers, for continuous additive manufacturing of at least one three-dimensional object by multiphoton photopolymerization (in particular, multi-color photopolymerization, more particularly, two-color photopolymerization). In this way, the device can be configured to continuously additively manufacture at least one three-dimensional object using multiphoton photopolymerization (particularly multicolor photopolymerization, more particularly two-color photopolymerization) of a photopolymerizable material (particularly a photopolymerizable polymer, such as a photopolymerizable polymer resin).

[0008] A corresponding localized polymerization process that can be performed using the device typically includes irradiating a photoinitiator with light of at least one wavelength to convert the molecules of the photoinitiator into a reactive state by sequential photoexcitation, wherein the molecules of the photoinitiator trigger a polymerization reaction of the polymerizable material locally within the working volume of the device. Thus, photopolymerization of the polymerizable material is typically achieved within the working volume of the device, for example, by irradiating the working volume of the device with light of at least one first wavelength and light of at least one additional wavelength (the additional wavelength being different from the first wavelength) via at least one irradiation device of the device, which causes the molecules of the photoinitiator to transition (e.g., due to absorption of light of the first wavelength) from an initial state in which the molecules of the photoinitiator (substantially) do not absorb light of the second or additional wavelength to an intermediate state having altered optical properties compared to the initial state, such that the molecules of the photoinitiator in the intermediate state absorb light of the additional wavelength, which causes the molecules of the photoinitiator to transition from the intermediate state to a reactive state, which locally triggers polymerization of the photopolymerizable material to produce at least one three-dimensional object within the working volume of the device. For example, the reverse reaction from the intermediate state to the initial state can be thermally induced.

[0009] Thus, the device may generally be implemented as a xolography device, i.e., a device configured to perform the basic principles of xolography. The basic principles of xolography are described in detail in WO 2020 / 245456 A1, the content of which is incorporated herein by reference.

[0010] As described above, the apparatus comprises a working volume configured to receive a photopolymerizable material, in particular a photopolymerizable polymer resin, to be irradiated with light of at least one wavelength, in particular at least two different wavelengths, to form a three-dimensional object. The working volume of the apparatus may be a local subvolume of a container volume of a container of the apparatus.

[0011] Thus, the device may comprise a container comprising a container volume. As described above, the container volume may comprise local sub-volumes, which local sub-volumes may represent the working volume of the device. The container volume may be defined by one or more container walls of the container. One or more container walls may be transparent to light of the first wavelength and / or light of the additional wavelength (as described in detail above). The respective transparent container walls may be configured as glass walls, or as translucent polymer walls, such as PC (polycarbonate), PMMA (polymethyl methacrylate) or COC (cyclic olefin copolymer). At least some of the container walls may exhibit at least a certain degree of diffraction and / or refraction effect on incident light of at least the first wavelength, as will be further described below.

[0012] As described above, the photopolymerizable material may include a photoinitiator molecule that can be converted into a reactive state (particularly via an intermediate state) by irradiation with light of at least one wavelength, wherein the photoinitiator molecule initiates local polymerization of the polymerizable material, thereby converting it into the reactive state. As a non-limiting example, the corresponding photoinitiator molecule may include a spiropyran molecule, i.e., a molecule of a spiropyran / merocyanine system, wherein the spiropyran form is the thermodynamically preferred form and, upon irradiation with light of a first wavelength, undergoes a ring-opening reaction, which results in the conversion of the spiropyran form into a metastable merocyanine form, which can be converted into the reactive state (particularly by absorbing light of an additional wavelength).

[0013] As further noted above, the apparatus includes at least one first illumination device, the first illumination device including at least one light source configured to illuminate light of a first wavelength into the working volume to generate at least one first light projection in the working volume. The at least one first light projection may include a plurality of light beams that traverse the working volume in at least one light plane. The at least one light plane may also be considered or denoted as a "common light plane." The at least one first light projection and the at least one light plane may also be considered or denoted as a "light sheet," respectively. By way of example, the at least one first illumination device may include at least one optical element for generating the at least one light plane. The at least one optical element may include at least one of the following: a Powell lens, a cylindrical lens, a diffractive optical element, etc. Additionally or alternatively, the at least one first illumination device may include a light deflection unit, such as a galvanometer scanner or a polygon scanner, for generating the at least one light plane. Thus, the at least one first illumination device may be configured as or include a light plane generator or a light sheet generator. The light emitted or irradiated by the at least one first irradiation device may include a wavelength within the following range: 350 nm to 500 nm, particularly 375 nm to 450 nm, more particularly 385 nm to 440 nm, more particularly 395 nm to 420 nm, and more particularly 400 nm to 410 nm. The light of the first wavelength may include a range or spectrum of wavelengths, particularly wavelengths that at least partially cover the aforementioned ranges. As an example, the first wavelength may be approximately 375 nm. Generally, the selection of the first wavelength takes into account at least the photochemical properties of the photoinitiator molecule, particularly its photochromic properties.

[0014] In particular, the at least one first illumination device can be configured to generate a plurality of individual light sheets, which extend through the working volume at at least one angle or at least two different angles relative to each other. The plurality of individual light sheets typically overlap in at least one light sheet overlap region. The plurality of individual light sheets can form a composite light sheet within the working volume. Additionally or alternatively, each individual light sheet comprises a main extension direction through the working volume. The main extension direction of the respective individual light sheet can be the extension direction of the respective individual light sheet between two opposite sides of the working volume or of a container defining the working volume. Thus, the at least one first illumination device can be configured to generate a plurality of individual light sheets, wherein the main extension directions of the respective individual light sheets extend through the working volume at at least one angle or at least two different angles relative to each other. The main extension directions of the individual light sheets typically intersect in at least one light sheet overlap region.

[0015] More particularly, the at least one first illumination device may be configured to generate at least four separate light sheets, wherein at least a first separate light sheet extends through the photocurable resin at a first angle, a second separate light sheet extends through the photocurable resin at an angle of 1° to 179°, in particular substantially 90°, relative to the first separate light sheet, a third separate light sheet extends through the photocurable resin at an angle of 1° to 179°, in particular substantially 90°, relative to the second separate light sheet, and a fourth separate light sheet extends through the photocurable resin at an angle of 1° to 179°, in particular substantially 90°, relative to the third separate light sheet. The same applies to the respective main extension directions of the respective separate light sheets.

[0016] The apparatus may include at least one light deflecting device assigned to at least one first illumination device. In particular, the at least one light deflecting device may be assigned to at least one light source of the at least one first illumination device. The at least one light deflecting device is configured to deflect light of at least one first wavelength emitted by the at least one light source of the at least one first illumination device into the working volume. The at least one light deflecting device may be configured to deflect light emitted by the at least one light source of the at least one first illumination device such that the light enters the working volume in at least two specific orientations and / or positions. The apparatus may include two corresponding light deflecting devices, the two corresponding light deflecting devices being arranged in an opposing arrangement relative to the working volume, such that light of the first wavelength enters the working volume from two or more different sides. The respective relative arrangement of the respective light deflecting devices may, for example, be located along a horizontal axis and / or a vertical axis. In this way, at least one light plane may be constructed from light entering the working volume from two different sides, in particular, from opposite sides (e.g., a side surface and / or top and bottom of the corresponding container). Each of the at least one light deflecting device may be assigned to a specific light source of the at least one first illumination device.

[0017] Thus, at least one first illumination device may comprise at least two light sources, wherein the first light source is configured to emit light of a first wavelength, which is deflected by a first light deflecting device to and into the working volume, and the additional or second light source is configured to emit light of a first wavelength, which is deflected by the additional or second light deflecting device to and into the working volume. In particular, the light emitted by each respective light source may generate a light plane within the working volume. The respective light plane may generally be constructed from or include a plurality of light beams that may be emitted simultaneously or sequentially. As an example, the light emitted by the first light source may generate a first light plane in the working volume, while the light emitted by the additional light source may emit an additional light plane in the working volume. Typically, the respective first light plane and the additional light plane overlap within the working volume to generate a composite light plane. The shape of the composite light plane depends on the shape of the first light plane and the additional light plane.

[0018] In exemplary embodiments where the apparatus is or includes a computed axial lithography (CAL) apparatus, the at least one first light projection may be a portion (e.g., a line) of an image projected by a first illumination device. In such embodiments, the first illumination device may be or include a digital light projection device. For example, the corresponding projected image may include multiple light sheets, in particular multiple adjacent light sheets.

[0019] As will be further described below, each corresponding light deflection device can be or include one or more light deflection elements, such as reflective elements. According to specific exemplary embodiments, at least one light deflection device can include at least one mirror element or at least one substrate, particularly a substrate having a cylindrical or generally cylindrical shape, which is rotatably supported about a rotation axis (e.g., its central axis or axis of symmetry) and has a plurality of light deflection elements (e.g., reflective elements) disposed on its outer surface. A drive device, such as an electric motor, an (electro)magnetic actuator, a piezoelectric actuator, or the like, can be connected or coupled to the at least one rotatable substrate to generate a drive force, thereby causing the at least one substrate to rotate about the rotation axis.

[0020] In an exemplary embodiment, the apparatus may additionally include at least one additional illumination device configured to sequentially project multiple images of light at an additional wavelength, different from the first wavelength, into the working volume. Each image at an additional wavelength may correspond to a specific portion, in particular a specific cross-section, of at least one three-dimensional object to be manufactured using the apparatus. Thus, the at least one additional illumination device may be configured as an image projector or include an image projector. The light emitted or illuminated by the at least one additional illumination device may include a wavelength within the following range: 400 nm to 1000 nm, in particular 425 nm to 750 nm, more particularly 450 nm to 675 nm, and even more particularly 500 nm to 650 nm. The additional wavelengths of light may include a range or spectrum of wavelengths, in particular wavelengths that at least partially cover the aforementioned respective ranges. The selection of the additional wavelengths typically takes into account at least the photochemical properties of the photoinitiator molecule, in particular its photochromic properties.

[0021] In an exemplary embodiment in which the apparatus further comprises at least one additional illumination device, the at least one additional illumination device is configured to project a plurality of images continuously, and the at least one additional illumination device can be configured to illuminate light of an additional wavelength into the working volume to generate a second light projection in the working volume, the second light projection intersecting the first light projection at a specific angle, in particular at an angle of 90°. Thus, the at least one light plane generated by the at least one first illumination device can be oriented at a certain angle, in particular at an angle of 90°, relative to the projection direction of the plurality of images generated by the at least one additional illumination device. In such an embodiment, the local polymerization process of the photopolymerizable material and the resulting formation of the three-dimensional object can occur in the region where the projected image generated by the at least one additional illumination device intersects the at least one light plane generated by the at least one first illumination device (or vice versa). As described above, the local polymerization process of the photopolymerizable material and the resulting formation of the three-dimensional object can be performed continuously (which is a characteristic of volumetric 3D printing relative to conventional additive manufacturing principles).

[0022] Typically, the projection of the plurality of images generated by the at least one additional illumination device not only covers the at least one light plane generated by the at least one first illumination device, but also the focal plane of the projection of the plurality of images is located in the at least one light plane. It is worth noting that dynamic or static optical properties of the photopolymerizable material, such as the refractive index, can be taken into account to adjust the focal plane of the projection of the plurality of images generated by the at least one additional illumination device.

[0023] In a further exemplary embodiment, the device may include at least one beam splitting unit, which is assigned to at least one light source of the device and configured to generate at least one light beam. The at least one beam splitting unit may be configured to split the at least one light beam generated by the at least one light source into a plurality of split beams, wherein one or more of the split beams may be used to project at least one light plane into the working volume. Alternatively or additionally, the one or more split beams may be used to project a corresponding image into the working volume, wherein each image may correspond to a specific portion, in particular a specific cross-section, of at least one three-dimensional object to be produced by the device. Thus, the device may operate with a single light source, and the corresponding light beam for projecting the at least one light plane may be generated by splitting an original light beam emitted by the at least one light source into at least one light beam using the at least one beam splitting unit, while the corresponding light beam for projecting the image may be generated by splitting an original light beam emitted by the at least one light source into at least one corresponding light beam using the at least one beam splitting unit. The at least one beam splitting unit may, for example, be designed as or include a beam splitting prism, which is arranged in the optical path downstream of the at least one light source.

[0024] As described above, at least one light plane is constructed from or includes at least one first light projection generated by at least one first illumination device. The first light projection includes a plurality of light beams that traverse, travel, or propagate through the working volume. The at least one light plane can be vertically oriented. The at least one light plane can have a lateral spatial extension and a vertical spatial extension. The lateral spatial extension of the at least one light plane can be the spatial extension of the at least one light plane along which the plurality of light beams traverse, travel, or propagate through the working volume. Thus, the lateral spatial extension of the at least one light plane can be the lateral distance between an entry point of a container (at which the plurality of light beams enter the container) and an exit point of an opposite container (at which the plurality of light beams exit the container). The vertical spatial extension of the at least one light plane can be the spatial extension of the at least one light plane between the uppermost light beam in the plurality of light beams of the at least one light plane and the lowermost light beam in the plurality of light beams of the at least one light plane. Thus, the lateral spatial extension of the at least one light plane can be the vertical distance between the uppermost light beam in the plurality of light beams and the lowermost light beam in the plurality of light beams of the at least one light plane. Thus, the vertical spatial extension of the at least one light plane can correspond to the height dimension of the at least one light plane. Thus, the spatial extension direction of the respective light beam may be the direction in which the respective light beam travels or propagates through the working volume.

[0025] The apparatus further comprises at least one light modulation device assigned to the at least one first illumination device. In particular, the at least one light modulation device can be assigned to at least one light source of the at least one first illumination device. If the at least one first illumination device comprises a plurality of light sources, each respective light source can have at least one light modulation device assigned thereto.

[0026] At least one light modulator is configured to modulate the spatial extension direction of two or more light beams among the multiple light beams of at least one light plane, so that the two or more light beams extend in a non-parallel arrangement relative to each other. At least one light modulator can be configured to actively and / or passively change the spatial extension direction and / or orientation of two or more light beams among the multiple light beams in at least one light plane, so that at least two light beams among the multiple light beams have a non-parallel arrangement relative to each other. The non-parallel arrangement of at least two light beams within at least one light plane typically results in the at least two light beams intersecting at at least one intersection point within the at least one light plane. In particular, a plurality of intersection points are generated at different positions in the at least one light plane, and at the plurality of intersection points, at least two light beams intersect. More particularly, a plurality of intersection points are generated at different positions within at least one forming area or within at least part of the at least one forming area, and at the plurality of intersection points, at least two light beams intersect. Thus, compared to the light sheet of a conventional volumetric 3D printing device comprising (substantially) parallel arranged (collimated) light beams and no intersecting light beams, the at least one light modulation device of the device described herein is capable of actively adjusting the spatial extension direction and / or orientation of at least two light beams within at least one light plane, so that at least two light beams extend in a non-parallel arrangement relative to each other within at least one light plane, which results in one or more intersection points within at least one light plane, at which two or more light beams intersect.

[0027] Typically, at least one intersection point where at least two light beams of the first wavelength intersect is arranged within at least one forming area of ​​the working volume. The at least one forming area comprises an area of ​​the working volume within which the photocurable resin is cured to form at least a portion of the three-dimensional object to be printed. In an exemplary embodiment of an apparatus implementing the principle of multi-color photopolymerization, in particular two-color photopolymerization, the at least one forming area therefore comprises an area of ​​the working volume within which light of the first wavelength intersects light of the second wavelength. Thus, the at least one light modulation device can be configured to generate light beams of the first wavelength that intersect at one or more intersection points within the at least one forming area at a specific angle, in particular, the angle being between 1° and 179°, more particularly less than 90°, preferably less than 70°, and more preferably less than 50°.

[0028] The at least one light modulator can be configured to generate one or more points within the working volume or at least one formation area, and to cause a light beam of the first wavelength to extend through the one or more points, respectively, based on at least one of the following speckle reduction principles: angular diversity, polarization diversity, and wavelength diversity. Thus, the at least one light modulator can be configured to generate at least two light beams of the first wavelength having different polarizations or polarization states at at least one point within the working volume, and / or to generate at least two light beams of different wavelengths (particularly within a specific wavelength range) at at least one point within the working volume. This can be a separate configuration of the at least one light modulator, in particular, independent of a configuration in which the at least one light modulator is configured to modulate the spatial extension direction of two or more of the plurality of light beams in at least one optical plane such that the two or more light beams extend in a non-parallel arrangement relative to one another.

[0029] The principle of angular diversity may include generating or using beams of a first wavelength extending at an angle relative to one another such that they intersect at at least one point (e.g., an intersection point). In particular, the principle of angular diversity may be implemented at an angle (in particular, perpendicularly) to a formation direction of the three-dimensional object to be printed, in particular to avoid or reduce a loss of resolution in the formation direction.

[0030] The principle of polarization diversity can include generating or using at least two light beams of a first wavelength, which have different polarizations or polarization states (in particular, two orthogonal polarization states) in at least one point within a working volume or at least one forming area. In particular, at least one light beam can be incoherent, for example generated by an optical fiber or by combining or overlapping light from at least two different light sources. The corresponding different polarizations or polarization states can include, for example, different linear polarizations or different circular polarizations. In such an embodiment, the at least one light modulation device can include at least one of the following: at least one optical fiber, at least one polarization element (for example, a polarization filter, in particular a polarization filter rotatable about an axis of rotation, which axis of rotation can be or include the axis of the light beam emitted by the light source of the first wavelength) and a beam expansion device (which is configured to expand the incident light beam, for example to generate a light sheet or a linear beam cross section or beam profile) and at least one collimating element (for example, a collimating lens).

[0031] The principle of wavelength diversity can include generating or using at least two light beams of a first wavelength, the at least two light beams having respective different wavelengths at at least one point within the working volume or at least one formation area. In particular, a broadband light source in combination with an optical filter (e.g., a bandpass filter with different angles of incidence) can generate respective different wavelengths. The respective different wavelengths can be, for example, wavelengths in the range of 350 nm to 500 nm, particularly 375 nm to 450 nm, more particularly 385 nm to 440 nm, more particularly 395 nm to 420 nm, and more particularly 400 nm to 410 nm. In such an embodiment, the at least one light modulation device may include at least one of the following: at least one optical filter element, a beam expansion device and at least one collimating element, the optical filter element being such as a bandpass filter, in particular a bandpass filter movable in at least one degree of freedom of movement, for example rotatable or tiltable about a rotation axis or a tilt axis, which rotation axis or tilt axis may be or include the axis of the light beam emitted by the light source of the first wavelength, the beam expansion device being configured to expand the incident light beam, for example to generate a light sheet or a linear beam cross section or beam profile respectively, the collimating element being such as a collimating lens.

[0032] In particular, at least one light modulation device may be configured to influence (in particular at least partially reduce) the optical coherence of the light beams in at least one light plane by actively changing the spatial extension direction and / or orientation of at least two light beams such that the at least two light beams extend in a non-parallel arrangement relative to each other, which results in the two or more light beams intersecting at one or more intersection points in the at least one light plane. Changing the spatial extension direction and / or orientation of at least two light beams such that the at least two light beams extend in a non-parallel arrangement relative to each other in at least one light plane also results in at least one light plane comprising light beams having an angled spatial extension direction when passing, traveling or propagating through the working volume. In particular, the at least two light beams may pass, travel or propagate through the working volume at an angle other than 0° relative to each other. The intersection of the at least two light beams at one or more intersection points in the at least one light plane may also include an overlap of the at least two light beams at the one or more intersection points.

[0033] Thus, at least one light modulating device can be configured to guide two or more light beams within at least one light plane, for example by diffusion and / or scattering, such that the at least one light plane comprises non-parallel and / or incoherent light beams. The beam steering can include adjusting the spatial extension of one or more light beams, in particular relative to their original spatial extension, such that the at least one light plane comprises non-parallel and / or incoherent light beams. This is in stark contrast to the operating principle of conventional light sheet generators, which generate a light sheet comprising non-intersecting collimated light beams (i.e., light beams having parallel spatial extensions and not intersecting). Thus, in contrast to conventional light sheets having a substantially rectangular basic shape defined perpendicularly by a parallel arrangement of an uppermost light beam and a lowermost light beam, the at least one light plane modulated by the at least one light modulating device can have a non-rectangular basic shape, such as a trapezoidal shape, defined perpendicularly by the non-parallel light beams within the working volume.

[0034] In particular, the at least one light modulation device can be configured to generate a modulated beam having properties that differ from those of a Gaussian beam. Thus, the at least one light modulation device can be configured to generate a modulated beam having, for example, a non-Gaussian beam profile. As an example, the at least one light modulation device can be configured to generate a modulated beam, such as an Airy beam or a Bessel beam, or a beam having properties similar to those of an Airy beam or a Bessel beam.

[0035] In a configuration of the apparatus, a first light plane is generated by light from a first light source with an assigned first modulation device, and an additional light plane is generated by light from an additional light source with an assigned additional light modulation device, each of which can have a non-rectangular basic shape within a working volume. Thus, because the corresponding non-rectangular first and additional light planes can overlap within the working volume, a composite light plane can be generated that also typically has a non-rectangular basic shape within the working volume, the shape of the composite light plane being defined by the corresponding shapes of the overlapping first and additional light planes. In an exemplary embodiment, the first and additional light planes each have a trapezoidal shape within the working volume, such that the composite light plane can have a hexagonal-like basic shape or a hexagonal basic shape, at least within the working volume. Similar considerations apply when the corresponding first and additional light planes have shapes other than trapezoidal within the working volume, and / or when additional light planes generated by additional light sources with assigned light modulation devices are added.

[0036] In exemplary embodiments in which the at least one first illumination device comprises two or more light sources, at least one respective light modulation device may be assigned to each respective light source.

[0037] Experimental results surprisingly show that actively generating corresponding intersection points where two or more light beams intersect in at least one optical plane can significantly reduce corresponding undesirable artifacts, and thus undesirable properties such as artifacts with (quasi-)regular or irregular stripes or patterns. This results in the optical appearance of the manufactured three-dimensional object resembling the optical appearance of a layer-by-layer buildup using conventional additive manufacturing methods, such as stereolithography and / or digital light processing. Consequently, the at least one light modulation device has a positive influence on the properties of the three-dimensional object manufactured using the device.

[0038] Furthermore, the implementation of the at least one light modulation device does not impair the resolution of the three-dimensional object to be printed in the formation direction.

[0039] Thus, an improved apparatus for volumetric 3D printing of at least one three-dimensional object is provided.

[0040] The at least one light modulation device may comprise, for example, one or more optically transmissive elements and / or one or more optically reflective elements and / or one or more optically diffractive elements. Thus, the configuration of the at least one light modulation device may be configured to influence the spatial extension direction and / or orientation of the light beams of the at least one light plane, thereby causing at least two light beams to extend in a non-parallel arrangement relative to one another due to one or more transmission effects and / or one or more reflection effects and / or one or more diffraction effects, the one or more transmission effects and / or one or more reflection effects and / or one or more diffraction effects being caused by the one or more corresponding optically transmissive elements and / or one or more corresponding optically reflective elements and / or one or more corresponding optically diffractive elements.

[0041] Non-limiting examples of corresponding optically transmissive elements are optical elements including one or more optically transmissive surfaces, such as optical lenses. The corresponding optically transmissive elements may have one or more shapes, such as curved shapes, angled shapes, and the like. The corresponding optically transmissive surfaces of the corresponding optically transmissive elements may be arranged in one or more spatial planes, such that, for example, two or more optically transmissive surfaces can be arranged at an angle relative to one another. As an example, a conical arrangement of optically transmissive surfaces is conceivable; thus, the optically transmissive element may be or include, for example, an axicon. Furthermore, the corresponding optically transmissive element may have, for example, a conical or roof-shaped shape. In either case, for example, the corresponding optically transmissive surface may be constructed from or include one or more optically transmissive coatings.

[0042] Non-limiting examples of corresponding optically reflective elements are optical elements including one or more optically reflective surfaces, such as optical lenses, mirrors, and the like. The corresponding optically reflective elements may have one or more shapes, such as curved shapes, angled shapes, and the like. The corresponding optically reflective surfaces of the corresponding optically reflective elements may be arranged in one or more spatial planes, such that, for example, two or more optically reflective surfaces can be arranged at an angle relative to one another. As an example, a conical arrangement of optically reflective surfaces is conceivable. Furthermore, the corresponding optically reflective elements may have, for example, a conical or roof-shaped shape. In either case, for example, the corresponding optically reflective surfaces may be constructed from or include one or more optically reflective coatings.

[0043] Non-limiting examples of corresponding optical diffraction elements are optical elements comprising one or more optical diffraction surfaces, such as optical lenses, in particular Fresnel lenses, spatial light modulators, metalenses, etc. The corresponding optical diffraction elements may have one or more shapes, such as curved shapes, inclined shapes, etc. The corresponding optical diffraction surfaces of the corresponding optical diffraction elements may be arranged in one or more spatial planes, such that, for example, two or more optical diffraction surfaces can be arranged at an angle relative to each other. As an example, the corresponding optical diffraction element may have, for example, a conical shape or a roof shape. In either case, for example, the corresponding optical diffraction surface may be constructed by or include one or more optical diffraction coatings.

[0044] It is contemplated that at least one optical element of at least one light modulation device includes, for example, a combination of at least two of the following: one or more corresponding optically transmissive surfaces, one or more corresponding optically reflective surfaces, and / or one or more corresponding optically diffractive surfaces, or a combination of at least two of the optically transmissive surfaces, optically reflective surfaces, and / or optically diffractive surfaces. For example, the corresponding optically transmissive surfaces, optically reflective surfaces, and / or optically diffractive surfaces may be constructed from, or include, one or more optically transmissive coatings, reflective coatings, and / or optically diffractive coatings.

[0045] In particular, at least one optically transmissive element and / or at least one optically reflective element and / or at least one optically diffractive element can be arranged directly in the optical path of the light beam of the at least one first illumination device (in particular, downstream of an optional collimator device or downstream of an optional objective device, the optional collimator device or the optional objective device, for example comprising a multi-lens assembly, such as a multi-lens assembly used in a classical microscope, as will be explained in more detail below), in order to change the orientation of the spatial extension direction of the at least one light beam so that the at least one light beam can intersect with at least one other light beam in the working volume. As an example, the corresponding optically reflective element (e.g., a mirror) can have a surface that is tilted relative to the initial spatial extension direction of the corresponding light beam. In particular, a relative arrangement of two or more corresponding optically reflective elements can be considered, each optically reflective element having a surface that is tilted relative to the initial spatial extension direction of the corresponding light beam, wherein each surface is configured to change the spatial extension direction of the at least one incident light beam by reflection so that the at least one light beam can intersect with at least one other light beam in the working volume. Similar considerations apply to the corresponding optically transmissive element and / or the corresponding optically diffractive element.

[0046] As described above, the at least one first illumination device can include at least one light source configured to generate light of a first wavelength and a light beam of the first wavelength, respectively. For example, the at least one light modulator can be arranged in an optical path extending between the at least one light source of the at least one first illumination device and the working volume. Thus, the at least one light modulator can be arranged upstream of the working volume. In other words, the at least one light modulator can be arranged external to the working volume and external to the corresponding container of the apparatus containing the working volume. In particular, the at least one light modulator can be arranged prior to an entry point into the corresponding container, where the plurality of light beams enter the container to form at least one light plane in the working volume. Arranging the at least one light modulator outside the container ensures that the at least one light modulator does not reduce the working volume and the available build volume. Furthermore, the at least one light modulator does not come into contact with the photopolymerizable material, thereby avoiding any potential undesirable interactions between the photopolymerizable material and the at least one light modulator or its components.

[0047] In an exemplary embodiment, at least one first illumination device may include a collimator device, such as a collimating lens, configured to collimate light emitted from at least one light source of the at least one first illumination device before entering the working volume. The at least one light modulator device may, for example, be disposed or constructed between the at least one light source and the collimator device. Thus, the at least one light modulator device may be disposed in the optical path of the light beam before it passes through the collimator device (upstream of the collimator device), such that the light passing through the collimator device may include at least two light beams that are already non-parallel relative to one another. In such a configuration, the collimator device can influence the aforementioned effect of directing the light beam such that at least one light plane includes non-parallel and / or incoherent light beams. Additionally or alternatively, at least one additional light modulator device may be disposed or constructed between the at least one collimator device and the working volume. Thus, the at least one light modulator device may be disposed in the optical path of the light beam after it passes through the collimator device (downstream of the collimator device). The light passing through the collimator device does include light beams that are already parallel relative to one another. In such a configuration, the collimator arrangement does not necessarily affect the above-described effect of guiding the light beams such that at least one light plane comprises non-parallel and / or incoherent light beams, at least in the absence of further light modulation devices in a respective upstream arrangement.

[0048] At least one collimator device can be supported so as to be movable in at least one degree of freedom of movement, in particular relative to at least one light source of at least one first illumination device or relative to the working volume. Thus, the aforementioned effect of directing the light beam such that at least one light plane comprises a non-parallel and / or incoherent light beam can also be achieved or supported by moving the at least one collimator device in at least one degree of freedom of movement. The respective degree of freedom of movement can include a translational movement of the at least one collimator device along at least one translational axis. The respective translational axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension of the at least one light plane. A non-parallel arrangement of the respective translational axis relative to the axis defining the transverse spatial extension of the at least one light plane can include, for example, an arrangement at an angle (in particular, perpendicular) to the axis defining the transverse spatial extension of the at least one light plane. In other words, the respective translational movement can, for example, include an upward and / or downward movement of the at least one collimator device relative to the at least one light plane. Additionally or alternatively, the respective degree of freedom of movement can include a rotational movement of the at least one collimator device about at least one rotational axis. The respective rotational axis can be arranged, for example, parallel or non-parallel relative to an axis defining the transverse spatial extension of the at least one light plane. A non-parallel arrangement of the respective rotational axis relative to the axis defining the transverse spatial extension of the at least one light plane can include, for example, an arrangement at an angle (in particular, perpendicular) relative to the axis defining the transverse spatial extension of the at least one light plane. In other words, the respective rotational movement can include, for example, a pivoting or tilting movement of the at least one collimator arrangement relative to the at least one light plane.

[0049] In a further exemplary embodiment, at least one first illumination device may include an objective lens device, such as an objective lens device including a multi-lens assembly, such as an objective lens device used in a conventional microscope. The at least one light modulator device may, for example, be disposed or constructed between the at least one light source and the objective lens device. Thus, the at least one light modulator device may be disposed in the optical path of the light beam before it passes through the objective lens device (upstream of the objective lens device), such that the light passing through the objective lens device may include at least two light beams that are already non-parallel in arrangement relative to one another. In such a configuration, the objective lens device can influence the effect of guiding the light beam described above, such that at least one light plane includes non-parallel and / or incoherent light beams. Additionally or alternatively, at least one additional light modulator device may be disposed or constructed between the at least one objective lens device and the working volume. Thus, the at least one light modulator device may be disposed in the optical path of the light beam after it passes through the objective lens device (downstream of the objective lens device). The light passing through the objective lens device does not necessarily include at least two light beams that are already non-parallel in arrangement relative to one another. In such a configuration, the objective arrangement does not necessarily affect the above-described effect of guiding the light beam such that at least one light plane comprises non-parallel and / or incoherent light beams, at least in the absence of further light modulation means in a respective upstream arrangement.

[0050] At least one objective device can be supported in a movable manner in at least one degree of freedom of movement, in particular, in at least one degree of freedom of movement relative to at least one light source of at least one first illumination device or relative to the working volume. Thus, the aforementioned effect of directing the light beam so that at least one light plane comprises a non-parallel and / or incoherent light beam can also be achieved or supported by moving the at least one objective device in at least one degree of freedom of movement. The corresponding degree of freedom of movement can include a translational movement of the at least one objective device along at least one translation axis. The corresponding translation axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension direction of the at least one light plane. The non-parallel arrangement of the corresponding translation axis relative to the axis defining the transverse spatial extension direction of the at least one light plane can include, for example, an arrangement at an angle (in particular, perpendicular) to the axis defining the transverse spatial extension direction of the at least one light plane. In other words, the corresponding translational movement can, for example, include an upward and / or downward movement of the at least one objective device relative to the at least one light plane. Additionally or alternatively, the corresponding degree of freedom of movement can include a rotational movement of the at least one objective device about at least one rotational axis. The corresponding rotational axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension direction of the at least one light plane. The non-parallel arrangement of the respective rotational axis relative to the axis defining the lateral spatial extension direction of the at least one light plane can comprise, for example, an arrangement at an angle (in particular perpendicular) relative to the axis defining the lateral spatial extension direction of the at least one light plane. In other words, the respective rotational movement can comprise, for example, a pivoting movement or a tilting movement of the at least one objective arrangement relative to the at least one light plane.

[0051] Additionally or alternatively, at least one light modulator or at least one component thereof (e.g., a transmissive element and / or a reflective element and / or a diffractive element) can also be supported so as to be movable in at least one degree of freedom of movement, in particular, so as to be movable in at least one degree of freedom of movement relative to at least one light source of at least one first illumination device or relative to the working volume. Thus, the aforementioned effect of directing the light beam such that at least one light plane comprises non-parallel and / or incoherent light beams can also be achieved or supported by moving the at least one first light modulator or at least one component thereof (in particular, relative to the light source or the container of the at least one first illumination device). The corresponding degree of freedom of movement can include translational movement of the at least one light modulator or at least one component thereof along at least one translation axis. The corresponding translation axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension of the at least one light plane. The non-parallel arrangement of the corresponding translation axis relative to the axis defining the transverse spatial extension of the at least one light plane can include, for example, an arrangement at an angle (in particular, perpendicular) to the axis defining the transverse spatial extension of the at least one light plane. In other words, the corresponding translational movement can, for example, include upward and / or downward movement of the at least one light modulator or at least one component thereof relative to the at least one light plane. Additionally or alternatively, the respective degree of freedom of movement may comprise a rotational movement of the at least one light modulating device or at least one component thereof about at least one axis of rotation. The respective axis of rotation may be arranged, for example, parallel or non-parallel relative to an axis defining the direction of the transverse spatial extension of the at least one light plane. The non-parallel arrangement of the respective axis of rotation relative to the axis defining the direction of the transverse spatial extension of the at least one light plane may comprise, for example, an arrangement at an angle (in particular perpendicular) relative to the axis defining the direction of the transverse spatial extension of the at least one light plane. In other words, the respective rotational movement may comprise, for example, a pivoting movement or a tilting movement of the at least one light modulating device or at least one component thereof relative to the at least one light plane.

[0052] By way of example, one or more optical elements (in particular optical lenses, such as microlenses or one or more microlens arrays) of at least one light modulation device can be arranged to respectively surround a working volume and a respective container defining the working volume. In particular, the one or more optical elements (this generally applies to all other components of the at least one light modulation device) can be respectively arranged on a supporting structure surrounding the working volume and a respective container defining the working volume. Thus, the supporting structure can define a receiving space, such as a cylindrical or polygonal receiving space, for respectively receiving the working volume and the respective container defining the working volume. Thus, the supporting structure can have a basic shape, such as a hollow cylinder or a polygon. The supporting structure can have an open portion (opening), such as an open lower portion, which enables the insertion and removal of the respective container defining the working volume. Providing a supporting structure is particularly advantageous for embodiments in which the at least one first illumination device is configured to generate a plurality of individual light sheets, in particular four individual light sheets, which extend through the working volume at at least two different angles relative to each other, thereby enabling the generation of a composite light sheet with desired properties.

[0053] The support structure can be at least partially transparent to light of the first and / or second wavelengths. In particular, the support structure can be transparent to light of the first and / or second wavelengths at a portion where light of the first and / or second wavelengths enters the working volume enclosed by the support structure. Thus, the support structure can be at least partially made of glass or a transparent polymer material, such as PC (polycarbonate), PMMA (polymethyl methacrylate), or COC (cyclic olefin copolymer).

[0054] The supporting structure may include one or more non-reflective surfaces to avoid undesirable optical effects based on reflection of light of at least the first wavelength. Corresponding non-reflective surfaces may be provided on the top and / or side of the supporting structure. For example, the corresponding non-reflective surfaces may be made of a non-reflective material. As an example, the supporting structure may include a flexible element, such as a foil, in particular a foil having one or more non-reflective surfaces. Specific examples are lens foils or lens sheets, respectively.

[0055] The support structure can be rotatably supported about a rotation axis, particularly one that is parallel to the central axis of the working volume and / or perpendicular to the rotation axis of the corresponding common light plane or light sheet. The support structure can be assigned at least one support device to support the support structure and maintain its orientation and / or position relative to the rotation axis and the working volume, respectively. The at least one support device can include one or more support elements, such as bearings, that are directly or indirectly connected to the support structure. In particular, at least three support elements can be provided, preferably evenly spaced along the circumference of the support structure. Furthermore, the support structure can be assigned at least one drive device (e.g., an electric motor) to generate a force or momentum that causes the support structure to rotate about the rotation axis. The at least one drive device can include one or more drive elements, such as gears, that can be connected or coupled to the support structure to transmit the corresponding force or momentum to the support structure. The at least one drive device can also form part of the support device, or vice versa. Thus, embodiments are contemplated in which the drive device transmits the force or momentum to the support structure via one or more gears and / or one or more bearings.

[0056] The support structure and / or the working volume and / or the container defining the working volume can each be supported in a movable manner relative to each other. In particular, the support structure can be supported in a movable manner in at least one operative position, in which the support structure is positioned relative to the working volume and the container defining the working volume, respectively, such that the support structure surrounds the working volume and the container defining the working volume, respectively, and can be supported in a movable manner in at least one inoperative position, in which the support structure is positioned relative to the working volume and the container defining the working volume, respectively, such that the support structure does not surround the working volume and the container defining the working volume, respectively. Thus, a conversion structure can be assigned to the support structure, which conversion structure is configured to convert the support structure into the at least one operative position and the inoperative position, respectively.

[0057] Additionally or alternatively, at least one first illumination device or at least one component thereof, in particular the light source of the at least one first illumination device, can be supported so as to be movable in at least one degree of freedom of movement, in particular relative to the at least one light plane. Thus, the aforementioned effect of directing the light beam such that the at least one light plane comprises a non-parallel and / or incoherent light beam can also be achieved or supported by moving the at least one first illumination device or at least one component thereof, in particular relative to the at least one light plane. The corresponding degree of freedom of movement can include translational movement of the at least one first illumination device or at least one component thereof along at least one translation axis. The corresponding translation axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension of the at least one light plane. A non-parallel arrangement of the corresponding translation axis relative to the axis defining the transverse spatial extension of the at least one light plane can include, for example, an arrangement at an angle (in particular, perpendicular) to the axis defining the transverse spatial extension of the at least one light plane. In other words, the corresponding translational movement can, for example, include upward and / or downward movement of the at least one first illumination device or at least one component thereof relative to the at least one light plane. Additionally or alternatively, the corresponding degree of freedom of movement can include rotational movement of the at least one first illumination device or at least one component thereof about at least one rotational axis. The respective rotational axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension of the at least one light plane. A non-parallel arrangement of the respective rotational axis relative to the axis defining the transverse spatial extension of the at least one light plane can include, for example, an arrangement at an angle (in particular, perpendicular) to the axis defining the transverse spatial extension of the at least one light plane. In other words, the respective rotational movement can, for example, comprise a pivoting movement of the at least one first illumination device or at least one component thereof relative to the at least one light plane.

[0058] Any movement of at least one of the at least one collimator device, the at least one light modulator device or at least one component thereof, or the at least one first illumination device or at least one component thereof can be achieved by at least one drive device, such as an electric motor, an (electro)magnetic actuator, a piezoelectric actuator, etc. The drive device is configured to generate a drive force to move at least one of the at least one collimator device, the at least one light modulator device or at least one component thereof, or the at least one first illumination device or at least one component thereof in at least one corresponding degree of freedom of movement. Therefore, the at least one drive device can be directly or indirectly coupled or connected to the at least one collimator device, the at least one light modulator device and / or at least one component thereof, or the at least one first illumination device or at least one component thereof, thereby achieving movement of the at least one collimator device, the at least one light modulator device or at least one component thereof, or the at least one first illumination device or at least one component thereof in at least one degree of freedom of movement. In an exemplary embodiment, each of the at least one collimator device, the at least one light modulator device or at least one component thereof, or the at least one first illumination device or at least one component thereof includes at least one corresponding drive device.

[0059] The operation of at least one drive device can be controlled by at least one hardware and / or software-implemented control unit assigned to the drive device. The control unit can be specifically configured to implement regular and / or irregular motion, in particular oscillatory and / or non-oscillatory motion, of at least one collimator device, at least one light modulator device, or at least one component thereof, and / or at least one first illumination device, or at least one component thereof, in at least one degree of freedom of motion. The control unit can be specifically configured to implement a motion profile of at least one collimator device, at least one light modulator device, or at least one component thereof, or at least one first illumination device, or at least one component thereof, in one or more degrees of freedom of motion. Experimental results have shown that both regular and irregular motion can reduce corresponding streaking or graining effects and positively impact the properties (in particular, surface and / or volumetric properties) of three-dimensional objects fabricated using the apparatus. In an exemplary embodiment, each of the at least one collimator device, at least one light modulator device, or at least one component thereof, and / or at least one first illumination device, or at least one component thereof, includes at least one corresponding drive device, and the operation of the corresponding drive devices can be controlled in a correlated or independent manner. In particular, the respective motion profiles can be achieved by dependently or independently controlling the operation of the respective drive devices assigned to at least one collimator device, at least one light modulation device or at least one component thereof, and / or at least one first illumination device or at least one component thereof.

[0060] Further exemplary and non-limiting configurations of the at least one light modulating device are as follows:

[0061] As described above, at least one light modulating device may comprise one or more optical elements. The corresponding optical elements may form corresponding components of the at least one light modulating device. Each optical element may be configured to change the original spatial extension direction and / or orientation of the incident light beam to generate a light beam having a different spatial extension direction and / or orientation relative to the original spatial direction and / or orientation. Thus, each optical element may be configured to generate at least one light beam having a spatial extension direction and / or orientation adjusted relative to the original spatial extension direction and / or orientation. In particular, at least one optical element may be configured to generate a plurality of light beams, each light beam having a spatial extension direction and / or orientation adjusted relative to the corresponding original spatial extension direction and / or orientation. In this way, the corresponding optical element may generate at least one light plane comprising two or more desired light beams arranged non-parallel to each other.

[0062] In exemplary embodiments, the corresponding optical elements can be designed as or include optical lenses and / or optical diffuser elements, the optical lenses being in particular microlenses, more in particular cylindrical microlenses, and the optical diffuser elements being in particular elliptical diffuser elements. Thus, at least one light modulation device can include an arrangement of a plurality of optical lenses, in particular microlenses, more in particular cylindrical microlenses; the corresponding light modulation device can be particularly considered or denoted as a microlens arrangement. Additionally or alternatively, at least one light modulation device can include an arrangement of optical diffuser elements; the corresponding light modulation device can be particularly considered or denoted as a diffuser arrangement.

[0063] The corresponding optical elements can be arranged in at least one row and / or column. Thus, at least one light modulation device can include an arrangement of at least one row and / or at least one column of corresponding optical elements. Thus, the individual optical elements can be arranged in a one-dimensional or multi-dimensional array, the array comprising at least one row and / or at least one column, with at least one row comprising at least one optical element and at least one column comprising at least one optical element. As described above, the corresponding optical elements can be or include optical lenses and / or optical diffuser elements, particularly microlenses, more particularly cylindrical microlenses, and optical diffuser elements, particularly elliptical diffuser elements.

[0064] One or more optical elements may be arranged or constructed on at least one side of at least one substrate element. Thus, at least one light modulating device includes at least one substrate element having one or more corresponding optical elements arranged or constructed on at least one side thereof. Specifically, the corresponding substrate element may include a first side and a second side opposite the first side. Thus, one or more optical elements may be arranged or constructed on the first side and / or the second side of the substrate element. By varying, for example, the arrangement, number, shape, and type of optical elements arranged on the respective first and / or second sides of the substrate element, the ability to change the spatial extension direction of an incident light beam can be adjusted.

[0065] As described above, at least one light modulation device can be arranged in the optical path of the light beam upstream of the working volume. This also applies to the at least one base element and the corresponding one or more optical elements arranged or constructed on at least one side thereof. More specifically, the at least one base element and the corresponding one or more optical elements arranged or constructed on at least one side thereof can be arranged upstream or downstream of a corresponding collimator device, which is arranged in the optical path extending between at least one light source of at least one first illumination device and the container of the device. By selecting the arrangement of the at least one base element and the corresponding one or more optical elements arranged or constructed on at least one side thereof upstream or downstream of the corresponding collimator device, the overall guidance effect can be adjusted so that at least one light plane includes a non-parallel and / or incoherent light beam generated by the at least one light modulation device.

[0066] In a further exemplary embodiment, in which the apparatus comprises a collimator device configured to collimate light emitted from the at least one light source of the at least one first illumination device and before it enters the working volume, the at least one light modulation device can be constructed by or comprise at least one optical lens, in particular a plano-concave lens or a free-form lens, arranged upstream or downstream of the collimator device. Thus, the at least one light modulation device can be constructed by or comprise at least one optical lens located upstream or downstream of the collimator device. Arranging the at least one optical lens upstream of the collimator device means arranging the at least one optical lens in a portion of the optical path extending between the at least one light source of the at least one first illumination device and the collimator device. Similarly, arranging the at least one optical lens downstream of the collimator device means arranging the at least one optical lens in a portion of the optical path extending between the collimator device and the working volume.

[0067] As described above, the apparatus may include at least one light deflecting device configured to deflect light emitted from at least one light source of at least one first illumination device toward a working volume, in particular, toward a collimator device (if present) arranged upstream of the working volume. In such exemplary embodiments, the at least one light modulation device may include at least one optical lens, in particular a plano-convex lens or a free-form lens, arranged upstream of the at least one light deflecting device. Arranging the at least one optical lens upstream of the at least one light deflecting device means arranging the at least one optical lens in a portion of the optical path extending between the at least one light source of the at least one first illumination device and the at least one light deflecting device. This arrangement is particularly useful for generating light with a line profile. Generating light with a line profile can particularly be combined with an additional optical lens disposed between the at least one light deflecting device and the collimator device arranged upstream of the working volume. As described above, the at least one light deflecting device may consist of or include at least one base body, in particular having a cylindrical or cylindrical basic shape, which is rotatably supported about its central axis or axis of symmetry and has a plurality of light deflecting elements, such as reflective elements, disposed on its outer surface.

[0068] In a further exemplary embodiment, the apparatus comprises at least one light deflecting device configured to deflect light emitted from at least one light source of at least one first illumination device toward a working volume, in particular toward a collimator device arranged upstream of the working volume, and the at least one light modulation device may comprise at least one beam steering device arranged upstream or downstream of the at least one light deflecting device. The at least one beam steering device may be configured to change the spatial extension direction and / or orientation of at least one light beam emitted from at least one light source of the at least one first illumination device and directed toward the light deflecting device (in an arrangement upstream of the light deflecting device) or toward the working volume (in an arrangement downstream of the light deflecting device). Thus, a desired non-parallel arrangement of at least two light beams relative to one another within at least one light plane may also be achieved or supported by the at least one beam steering device arranged upstream or downstream of the at least one light deflecting device. Arranging the at least one beam steering device upstream of the at least one light deflecting device means arranging the at least one beam steering device in a portion of the optical path extending between the at least one light source of the at least one first illumination device and the at least one light deflecting device. Arranging the at least one beam steering device downstream of the at least one light deflecting device means that the at least one beam steering device is arranged in the portion of the optical path extending between the at least one light deflecting device and the working volume.

[0069] The at least one beam-deflecting device may include at least one optically transmissive element, such as a glass plate, that is supported so as to be movable in at least one degree of freedom of movement. This configuration is particularly suitable when the at least one beam-deflecting device is arranged upstream of the at least one light-deflecting device. The at least one beam-deflecting device may be configured to change the spatial extension and / or orientation of at least one light beam emitted from at least one light source of the at least one first illumination device and directed toward the at least one light-deflecting device by one or more movements of the at least one optically transmissive element in at least one degree of freedom of movement. The respective degrees of freedom of movement may be or include translational movement of the at least one optically transmissive element along a translation axis and / or rotational movement of the at least one optically transmissive element about a rotational axis, such as a pivoting movement or a tilting movement. As described above, the at least one light-deflecting device may consist of or include at least one base body, particularly having a cylindrical or cylindrical basic shape, that is supported so as to be rotatable about its central axis or axis of symmetry and on whose outer surface a plurality of light-deflecting elements, such as reflective elements, are arranged. The movement of at least one optically transmissive element of at least one light beam steering device can be synchronized with the rotational movement of the base body of at least one light deflecting device by at least one hardware and / or software-implemented control unit, which is configured to control the movement of at least one optically transmissive element and the base body.

[0070] In a further exemplary embodiment, the at least one beam steering device may include at least one optical reflective element, such as a mirror, that is movably supported with at least one degree of freedom of movement. This configuration is particularly suitable for arrangements in which the at least one beam steering device is arranged upstream or downstream of the at least one light deflecting device. When arranged upstream of the at least one light deflecting device, the at least one beam steering device may be configured to change the spatial extension and / or orientation of at least one light beam emitted from at least one light source of the at least one first illumination device and directed toward the at least one light deflecting device by one or more movements of the at least one optical reflective element in at least one degree of freedom of movement. When arranged downstream of the at least one light deflecting device, the at least one beam steering device may be configured to change the spatial extension and / or orientation of at least one light beam deflected from the at least one light deflecting device and directed toward the working volume by one or more movements of the at least one optical reflective element in at least one degree of freedom of movement. The respective degrees of freedom of movement may be or include translational movement of the at least one optical reflective element along a translational axis and / or rotational movement of the at least one optical reflective element about a rotational axis, such as a pivoting or tilting movement. As described above, the at least one light-deflecting device can be formed from or include at least one base body, in particular having a cylindrical or cylindrical basic shape, which is rotatably supported about its central axis or axis of symmetry and on whose outer surface a plurality of light-deflecting elements, such as reflective elements, are arranged. The movement of the at least one reflective element of the at least one beam-steering device can be synchronized with the rotational movement of the base body of the at least one light-deflecting device by at least one hardware and / or software-implemented control unit, which is configured to control the movement of the at least one optically transmissive element and the base body.

[0071] In a further exemplary embodiment, at least one light modulation device may comprise at least one adaptive optical element having an adaptive and therefore variable shape. Adaptive and therefore variable shape means that the at least one adaptive optical element can change its geometric dimensions (e.g. its length and / or width and / or height, in particular relative to a reference state) in at least one spatial direction. Thus, the at least one adaptive optical element can be configured to change the spatial extension direction and / or orientation of the at least one light beam by one or more adaptive changes or variations of its shape. In particular, the respective adaptive optical element can be arranged downstream of the respective light deflection device. The respective adaptive optical element can in particular be configured to dynamically change the focal length of the light beam incident into the working volume based on the respective changes in its shape. A control unit implemented by hardware and / or software can be assigned to the at least one adaptive optical element, which control unit is configured to control the changes and / or variations in the shape of the at least one adaptive optical element.

[0072] The at least one adaptive optical element can be designed as or include an adaptive optical transmissive element, in particular an adaptive lens, more in particular a liquid lens, or an adaptive optical reflective element, in particular an adaptive mirror, more in particular a liquid mirror.

[0073] The at least one adaptive optical element can be arranged upstream or downstream of the at least one light deflecting device.

[0074] In an exemplary embodiment, the device includes at least one light deflection device, which includes at least one base body, in particular a base body having a cylindrical or generally cylindrical shape, which can be rotatably supported about its central axis or axis of symmetry, and a plurality of light deflection elements, such as reflective elements, arranged on the outer surface of the base body. At least one light modulation device can include at least one optical modulation element attached to the outer surface of the base body. In particular, the at least one optical modulation element can be attached to the outer surface of at least one corresponding light deflection element arranged on the outer surface of the base body. The corresponding optical modulation element can be a transmissive element, such as a glass element, which can achieve a desired non-parallel arrangement of the at least two light beams in at least one optical plane.

[0075] Additionally or alternatively, in exemplary embodiments, the apparatus includes at least one light deflection device, the light deflection device comprising at least one substrate, in particular a substrate having a cylindrical or generally cylindrical shape, which substrate can be rotatably supported about its central axis or axis of symmetry, and the at least one light modulation device can comprise a one-dimensional or multi-dimensional surface structure on the outer surface of the substrate. The corresponding one-dimensional or multi-dimensional surface structure on the outer surface of the substrate can comprise a specific arrangement of reflective and / or transmissive and / or diffractive elements, for example, an alternating arrangement of reflective and / or transmissive and / or diffractive elements. The corresponding reflective and / or transmissive and / or diffractive elements can have the same shape or different shapes. By way of example, the corresponding one-dimensional or multi-dimensional surface structure on the outer surface of the substrate can comprise a specific arrangement of reflective and / or transmissive and / or diffractive elements having a convex, concave, cylindrical, polygonal, or other shape, for example, an alternating arrangement of reflective and / or transmissive and / or diffractive elements having a convex, concave, cylindrical, polygonal, or other shape. Additionally or alternatively, the corresponding one-dimensional or multi-dimensional surface structuring of the outer surface of the substrate may include chemical and / or physical modification of the surface of the light-deflecting elements on the outer surface of the substrate. The corresponding chemical and / or physical modification may be achieved by a deposition process in which at least one optically effective deposition material is deposited on the at least one light-deflecting element to adjust its optical properties; by an etching process in which the surface of the at least one light-deflecting element is etched to adjust its optical properties, etc.

[0076] In any embodiment, the light modulation device or at least one light modulation device can be configured to generate incoherent light. Thus, the corresponding light modulation device can include at least one incoherent light source (e.g., a light emitting diode) configured to generate incoherent light and / or at least one optical light guide (e.g., an optical fiber) configured to modify the properties of coherent light to thereby obtain incoherent light. Furthermore, devices for reducing the longitudinal coherence length of the emitted light, such as so-called speckle reducers, are also contemplated. The incoherent light can include corresponding intersecting beams, thereby achieving a desired beam intersection within the working volume.

[0077] As mentioned above, the working volume can be provided by at least one container of the apparatus. This container defines a container volume for receiving the photopolymerizable material. It is also conceivable that the container is supported in a movable manner in at least one degree of freedom of movement, for example relative to at least one light source of at least one first illumination device, so as to achieve or support a desired non-parallel arrangement of at least two light beams within at least one light plane, for example due to diffraction effects of the material forming the container wall. As noted above, at least a portion of the container wall can achieve at least a certain degree of diffraction effects, such that movement of the container in at least one degree of freedom of movement can achieve or support the desired non-parallel arrangement of the at least two light beams within at least one light plane.

[0078] In any embodiment, the device may include a determination device configured to determine surface and / or volume characteristics of a three-dimensional object manufactured using the device. The determination device may include a detection unit, such as an optical detection unit, such as a camera, configured to detect at least one information indicating surface and / or volume characteristics of the three-dimensional object manufactured using the device. The at least one information indicating surface and / or volume characteristics of the three-dimensional object manufactured using the device may be transmitted to a control unit implemented by hardware and / or software, the control unit being configured to control the operation of at least one light modulation device based on the at least one information. In this way, a process control loop may be implemented. This is particularly applicable when the corresponding information indicating surface and / or volume characteristics of the three-dimensional object manufactured using the device is used to control the operation of at least one light modulation device online.

[0079] A second aspect of the present invention relates to a method for volumetric 3D printing to form a three-dimensional object. The method comprises at least the following steps: generating a first light projection in a working volume by means of at least one first illumination device, the at least one first illumination device being configured to irradiate light of a first wavelength into the working volume comprising a photopolymerizable material (in particular a photopolymerizable polymer resin), the first light projection comprising a plurality of light beams passing through the working volume in at least one light plane; and modulating the spatial extension direction of two or more of the plurality of light beams in at least one light plane by means of at least one light modulation device assigned to the at least one first illumination device, such that the two or more light beams extend in a non-parallel arrangement relative to each other. Preferably, the method is performed using light of at least two different wavelengths, wherein the first wavelength is used to generate or project the corresponding light plane and the additional wavelength is used to generate or project the corresponding image of a cross-section of the three-dimensional object to be constructed. As described above, the first wavelength is typically smaller than the additional wavelength. The method thus preferably implements the principle of so-called two-color photopolymerization.

[0080] The method can be implemented by the apparatus according to the first aspect of the present invention. Therefore, all descriptions about the apparatus according to the first aspect of the present invention are also applicable to the method according to the second aspect of the present invention, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] As these and other advantages and features will become apparent hereinafter, a more complete understanding of the present invention may be obtained through reference to the following description with reference to the accompanying drawings, in which:

[0082] Figures 1 to 14 , respectively, show schematic diagrams of apparatuses for volume 3D printing of at least one three-dimensional object according to exemplary embodiments in top views;

[0083] Figure 15 Example experimental results showing characteristics of objects made according to example embodiments and characteristics of reference objects not made according to example embodiments; and

[0084] Figures 16 to 18 2 and 3 show schematic diagrams of apparatuses for volumetric 3D printing of at least one three-dimensional object according to additional exemplary embodiments. DETAILED DESCRIPTION

[0085] Figure 1 A schematic diagram of a device 1 for volumetric 3D printing of at least one three-dimensional object 2 according to an exemplary embodiment is shown in top view. For ease of reference, an exemplary coordinate system of the device 1 is added to the figure, showing the coordinate axes x, y and z, which also applies to Figures 2 to 14 as well as Figures 16 to 18 Schematic diagram in .

[0086] The apparatus 1 is generally configured to perform a volumetric 3D printing process to form one or more three-dimensional objects. The corresponding volumetric 3D printing process may include at least one local polymerization process of a photopolymerizable material for continuous additive manufacturing of the one or more three-dimensional objects by multiphoton photopolymerization, in particular multicolor photopolymerization, more particularly two-color photopolymerization. Thus, the apparatus 1 may be configured to perform one or more local polymerization processes of a photopolymerizable material (e.g., a photopolymerizable monomer resin, wherein the polymerizable material may include but is not limited to acrylates, methacrylates, thiols + ene, epoxides, oxiranes, oxetanes, or vinyl ethers) and / or a photopolymerizable oligomer resin (wherein the polymerizable material may include but is not limited to acrylates, methacrylates, thiols + ene, epoxides, oxiranes, oxetanes, or vinyl ethers) for continuous additive manufacturing of the one or more three-dimensional objects by multiphoton photopolymerization, in particular multicolor photopolymerization, more particularly two-color photopolymerization. In this way, the device 1 can be configured to continuously additively manufacture one or more three-dimensional objects using multi-photon photopolymerization (particularly multi-color photopolymerization, more particularly two-color photopolymerization) of a photopolymerizable material (particularly a photopolymerizable polymer, such as a photopolymerizable polymer resin).

[0087] A corresponding localized polymerization process that can be performed using the apparatus 1 can include irradiating a photoinitiator with light of a first wavelength L1 and light of an additional wavelength L2 to convert the molecules of the photoinitiator into a reactive state by sequential photoexcitation, in which the molecules of the photoinitiator locally initiate a polymerization reaction of the polymerizable material in the working volume 3 of the apparatus 1. Thus, photopolymerization of the photopolymerizable material can be achieved within the working volume 3 of the apparatus 1 by irradiating the working volume 3 of the apparatus 1 with light of a first wavelength L1 and light of an additional wavelength L2 (the additional wavelength being different from the first wavelength) via at least one first irradiation device 4 and at least one additional irradiation device 5 of the apparatus 1, which causes the molecules of the photoinitiator to transform (e.g., due to absorption of the light of the first wavelength L1) from an initial state in which the molecules of the photoinitiator (substantially) do not absorb the light of the additional wavelength L2 to an intermediate state in which optical properties are altered compared to the initial state, such that the molecules of the photoinitiator in the intermediate state absorb the light of the additional wavelength L2, which causes the molecules of the photoinitiator to transform from the intermediate state into the reactive state, thereby locally initiating polymerization of the photopolymerizable material within the working volume 3 of the apparatus 1 to fabricate one or more three-dimensional objects.

[0088] In particular, in the initial state, the attenuation coefficient or extinction coefficient of the photoinitiator molecules for the first wavelength of light L1 may be less than 5000 L mol -1 cm -1 , especially less than 1000 L mol -1 cm -1 , more particularly less than 500 L mol -1 cm -1 , more particularly less than 250 L mol -1 cm -1 , more particularly less than 100 L mol -1 cm -1 The attenuation coefficient or extinction coefficient can be calculated according to Beer's law from the absorbance of a sample with known photoinitiator concentration, as measured using, for example, a "Cary 60" UV-Vis spectrophotometer supplied by Agilent Technologies.

[0089] For example, the reverse reaction of the photoinitiator molecules from the intermediate state to the initial state can be achieved by thermal induction.

[0090] The device 1 may generally be implemented as a xolography device, i.e., a device configured to perform the basic principles of xolography. The basic principles of xolography are described in detail in WO 2020 / 245456 A1, the contents of which are incorporated herein by reference.

[0091] As described above, the device 1 includes a working volume 3, which is configured to accommodate a photopolymerizable material (not explicitly shown in the figure), in particular a photopolymerizable polymer resin, which is irradiated by at least two different wavelengths of light L1, L2 to form one or more three-dimensional objects 2.

[0092] As is apparent from the figure, the working volume 3 of the device 1 may be a local subvolume of a container 6 of the device 1. Thus, the device 1 may include a container 6 including a container volume 6.1 including a local subvolume that may represent the working volume 3 of the device 1. The container volume 6.1 may be defined by one or more container walls 6.2-6.5 of the container 6. The container walls 6.2-6.5 may be transparent to the light of the first wavelength L1 and the light of the additional wavelength L2. Figure 1 In an exemplary embodiment, container walls 6.2-6.4 include wall portions 6.2a and 6.3a (windows) that are transparent to light of the first wavelength L1, and at least one wall portion 6.4a (window) that is transparent to light of the additional wavelength L2. The corresponding transparent container walls 6.2-6.5 or container wall portions 6.2a-6.4a, respectively, can be configured as glass walls or translucent polymer walls, such as PC (polycarbonate), PMMA (polymethyl methacrylate), or COC (cyclic olefin copolymer). At least some of the container walls 6.2-6.5 or container wall portions 6.2a-6.4a can exhibit, at least to some extent, a diffraction and / or refraction effect on incident light L1 of at least the first wavelength.

[0093] In the exemplary embodiment, the apparatus 1 comprises a first illumination device 4 comprising two light sources 4.1, each light source 4.1 being configured to generate light of a first wavelength L1 and irradiate the same into the working volume 3, and an additional illumination device 5 comprising a light source 5.1, the light source 5.1 being configured to generate light of an additional wavelength L2 and irradiate the same into the working volume 3.

[0094] Notably, the first illumination device 4 is configured to irradiate light L1 of a first wavelength into the working volume 3 to generate a first light projection 7 within the working volume 3. The first light projection 7 comprises a plurality of light beams 7.1 that traverse the working volume 3 in a light plane 8. In an exemplary embodiment, the light plane 8 extends vertically in the xy plane of the coordinate system and may also be considered or denoted as a "common light plane." The first light projection 7 and the light plane 8 may also be considered or denoted as a "light sheet," respectively. Thus, the first illumination device 4 is configured as or comprises a light plane generator or light sheet generator. The light L1 emitted or irradiated by the first illumination device 4 may comprise a wavelength within the following range: for example, 350 nm to 500 nm, particularly 375 nm to 450 nm, more particularly 385 nm to 440 nm, more particularly 395 nm to 420 nm, and even more particularly 400 nm to 410 nm. The light L1 of the first wavelength may comprise a range or spectrum of wavelengths, particularly wavelengths that at least partially cover the aforementioned range. The first wavelength is typically selected taking into account at least the photochemical properties of the photoinitiator molecule, particularly its photochromic properties.

[0095] The additional illumination device 5 is configured to irradiate light L2 of an additional wavelength into the working volume 3 to produce a second light projection 10 in the working volume 3. Thus, the additional illumination device 5 can be configured as an image projector or include an image projector. The light L2 emitted or illuminated by the additional illumination device 5 can include a wavelength within the range of, for example, 400 nm to 1000 nm, particularly 425 nm to 750 nm, more particularly 450 nm to 675 nm, and even more particularly 500 nm to 650 nm. The additional wavelength light L2 can include a range or spectrum of wavelengths, particularly wavelengths that at least partially cover the aforementioned range. The selection of the additional wavelength typically takes into account at least the photochemical properties of the photoinitiator molecule, particularly its photochromic properties.

[0096] Figure 1It is shown that the second light projection 10 can intersect the first light projection 7 at a specific angle, in particular an angle of 90°. Therefore, the light plane 8 generated by the first illumination device 4 can be oriented at a certain angle relative to the projection direction of the multiple images generated by the additional illumination device 5, in particular an angle of 90°. The local polymerization process of the photopolymerizable material and the formation of the three-dimensional object 2 thereby can occur in the area where the projection image generated by the additional illumination device 5 intersects the light plane 8 generated by the first illumination device 4 (and vice versa). As described above, the local polymerization process of the photopolymerizable material and the formation of the three-dimensional object 2 thereby can be carried out continuously (this is a feature of volumetric 3D printing compared to traditional additive manufacturing principles). During the 3D printing process using the device 1, the light plane 8 or the container 6 can be moved to form the three-dimensional object 2.

[0097] Typically, the projection of the plurality of images generated by the additional illumination device 5 not only covers the light plane 8 generated by the first illumination device 4, but the focal plane of the projection of the plurality of images is also located in the light plane 8. It is worth noting that the dynamic or static optical properties of the photopolymerizable material, such as the refractive index, can be taken into account to adjust the focal plane of the projection of the plurality of images generated by the additional illumination device 5.

[0098] Figure 1 It is shown that the apparatus 1 may comprise two light deflecting devices 9 assigned to respective first illumination devices 4. The light deflecting devices 9 are configured to deflect light L1 of a first wavelength, which is emitted by a respective light source 4.1 of a respective first illumination device 4, towards the working volume 3. Thus, the light deflecting devices 9 are configured to deflect the light L1 emitted by the light source 4.1 of the first illumination device 4 such that the light L1 enters the working volume 3 at two specific locations, namely a first location provided by the wall portion 6.2a of the container wall 6.2 and a second location provided by the wall portion 6.3a of the container wall 6.4. Figure 1 The diagram shows that two corresponding light deflection devices 9 can be arranged in an opposing arrangement relative to the working volume 3, which causes light L1 of the first wavelength to enter the working volume 3 from two different sides. In this way, a light plane 8 can be constructed from light L1 entering the working volume 3 from two opposite sides. Therefore, each light deflection device 9 is assigned to a light source 4.1 of the first illumination device 4. Thus, the first illumination device 4 includes two light sources 4.1: the first light source 4.1 emits light L1 of the first wavelength, which is deflected by the first light deflection device 9 toward and into the working volume 3; and the second light source 4.1 emits light L1 of the first wavelength, which is deflected by the second light deflection device 9 toward and into the working volume 3.

[0099] from Figure 1 It is obvious that each respective light deflecting device 9 can be or comprise one or more light deflecting elements 9.1, such as reflective elements. Figure 1 In an embodiment, each light deflection device 9 includes a base 9.2, which in particular has a cylindrical or cylindrical basic shape and is rotatably supported, for example, about a rotation axis A1 (e.g., its central axis or axis of symmetry), and has a plurality of light deflection elements 9.1 (e.g., reflective elements) disposed on its outer surface. A drive device (not shown), such as an electric motor, an (electro)magnetic actuator, a piezoelectric actuator, etc., may be connected or coupled to the corresponding base 9.2 to generate a drive force, thereby causing the corresponding base 9.2 to rotate about the rotation axis A1. In alternative embodiments, the corresponding light deflection device 9 may include a mirror, in particular a movable mirror, which may replace the corresponding base 9.2.

[0100] As described above, light plane 8 is constructed from or includes at least one first light projection 7 generated by light source 4.1 of first illumination device 4. First light projection 7 includes a plurality of light beams that traverse, travel, or propagate through working volume 3. Light plane 8 can be vertically oriented, meaning that light plane 8 can extend vertically within the xy plane. Light plane 8 can have a lateral spatial extension (see x-direction) and a vertical spatial extension (see y-direction). Thus, the lateral spatial extension of light plane 8 can be the spatial extension of light plane 8 along which the plurality of light beams traverse, travel, or propagate through working volume 3. Thus, the lateral spatial extension of light plane 8 can be the lateral distance between an entry point into container 6 (e.g., see container wall portion 6.2a, at which the plurality of light beams enter container 6) and an opposite exit point into container 6 (e.g., see container wall portion 6.3a, at which the plurality of light beams exit container 6). The vertical spatial extension of light plane 8 can be the spatial extension of light plane 8 between the uppermost light beam in the plurality of light beams in light plane 8 and the lowermost light beam in the plurality of light beams in light plane 8. Thus, the lateral spatial extension direction of the light plane 8 may be the vertical distance between the uppermost light beam of the plurality of light beams and the lowermost light beam of the plurality of light beams. Thus, the vertical spatial extension direction of the light plane 8 may correspond to the height dimension of the light plane (see y direction).

[0101] The device 1 further comprises at least one light modulating device 11 assigned to the first illumination device 4. In particular, at least one light modulating device 11 can be assigned to each light source 4.1 of the first illumination device 4. Each respective light modulating device 11 is configured to modulate the spatial extension direction of two or more light beams of the plurality of light beams of the light plane 8 (e.g. Figures 2 to 14The light modulating device 11 may be configured to actively and / or passively change the spatial extension direction and / or orientation of two or more of the plurality of light beams in the light plane 8, such that at least two of the plurality of light beams have a non-parallel arrangement relative to each other. The non-parallel arrangement of at least two light beams in the light plane 8 typically results in the at least two light beams intersecting at at least one intersection point P within the light plane 8 (e.g., as shown in FIG. 1 ). Figure 5 exemplarily shown). In particular, a plurality of intersection points are generated at different locations in the light plane 8, at which at least two light beams intersect. Compared to the light sheet of a conventional volume 3D printing device comprising parallel arranged (collimated) light beams without intersecting light beams, the corresponding light modulation device 11 of the device 1 is capable of actively adjusting the spatial extension direction and / or orientation of at least two light beams in the light plane 8, so that at least two light beams extend in a non-parallel arrangement relative to each other in the light plane 8, which results in one or more intersection points in the light plane 8 where two or more light beams intersect.

[0102] Typically, at least one intersection point where at least two light beams of the first wavelength intersect is arranged within at least one forming area of ​​the working volume 3. The at least one forming area comprises a region of the working volume 3 in which the photocurable resin is cured to form the three-dimensional part to be printed. In an exemplary embodiment of the device 1 implementing the principle of multi-color photopolymerization, in particular two-color photopolymerization, the at least one forming area thus comprises a region of the working volume 3 in which the light beams of the first wavelength L1 intersect with the light beams of the second wavelength L2. Therefore, the at least one light modulation device 9 can be configured to generate light beams of the first wavelength that intersect at one or more intersection points within the at least one forming area at a specific angle, in particular, the angle being between 1° and 179°, more particularly less than 90°, preferably less than 70°, and more preferably less than 50°.

[0103] In particular, the respective light modulation device 11 may be configured to influence (in particular at least partially reduce) the optical coherence of the light beams within the light plane 8 by actively changing the spatial extension direction and / or orientation of at least two light beams such that the at least two light beams extend in a non-parallel arrangement relative to each other, which results in the two or more light beams intersecting at one or more intersection points within the light plane 8. Changing the spatial extension direction and / or orientation of at least two light beams such that the at least two light beams extend in a non-parallel arrangement relative to each other within the light plane 8 also results in the light plane 8 comprising light beams having an angled spatial extension direction when passing, travelling or propagating through the working volume 3. In particular, the at least two light beams may pass, travel or propagate through the working volume 3 at an angle other than 0° relative to each other. The intersection of the at least two light beams at one or more intersection points within the light plane 8 may also comprise an overlap of the at least two light beams at the one or more intersection points.

[0104] The respective light modulation device 11 can in particular be configured to direct two or more light beams within the light plane 8 such that the light plane 8 comprises respectively non-parallel and incoherent light beams. In contrast to conventional light sheets having a substantially rectangular basic shape defined perpendicularly by a parallel arrangement of an uppermost light beam and a lowermost light beam, the light plane 8 modulated by the respective light modulation device 11 of the device 1 can have a non-rectangular basic shape, such as a trapezoidal shape, defined perpendicularly by non-parallel light beams within the working volume 3 (see, for example, Figures 4 to 7 ).

[0105] As an example, the corresponding light modulation device 11 can be configured to generate a modulated beam having characteristics different from those of a Gaussian beam. Thus, the corresponding light modulation device 11 can be configured to generate, for example, a modulated beam having a non-Gaussian beam profile. As an example, the corresponding light modulation device 11 can be configured to generate a modulated beam, such as an Airy beam or a Bessel beam, or a beam having characteristics similar to those of an Airy beam or a Bessel beam.

[0106] exist Figure 3 In the exemplary embodiment, it is shown that both the first light plane 8 and the second light plane 8 can have a non-rectangular basic shape within the working volume 3, the first light plane 8 being generated by a first light modulation device 11 assigned to the first light source 4.1, and the second light plane 8 being generated by a second light modulation device 11 (not shown) assigned to the second light source 4.1 (not shown). In this way, since the corresponding non-rectangular first and second light planes 8 overlap within the working volume 3, a synthetic light plane R can be generated within the working volume 3, the shape of the synthetic light plane R being defined by the overlapping first and second light planes 8. In the exemplary embodiment, both the first and second light planes 8 have a trapezoidal shape within the working volume 3, so that the synthetic light plane R can have a hexagonal basic shape at least in the working volume 3 ( Figure 3For example, the corresponding synthetic light plane R having a hexagonal basic shape or a hexagonal basic shape can have an upper obtuse angle and a lower obtuse angle arranged relative to each other.

[0107] Similar considerations apply when the respective first and second light planes 8 have other shapes than trapezoidal within the working volume 3 and / or when additional light planes 8 generated by additional light sources 4 . 1 with designated light modulation means 11 are added.

[0108] These principles generally apply to all embodiments, ie a composite light plane R may be present in all embodiments in which the corresponding light planes 8 overlap.

[0109] like Figure 1 As shown in the exemplary embodiment of FIG, in the exemplary configuration in which the first illumination device 4 comprises two light sources 4.1, a corresponding light modulation device 11 is assigned to each corresponding light source 4.1, so that the device 1 may comprise a plurality of light modulation devices 11. It is worth noting that Figure 1 The light modulation device 11 is only schematically shown in FIG. Specific exemplary embodiments of the light modulation device 11 are as follows Figures 2 to 14 shown.

[0110] By actively generating corresponding intersection points of two or more light beams within the light plane 8, undesirable artifacts can be significantly reduced, thereby reducing undesirable properties, such as artifacts with (quasi-)regular or irregular stripes or patterns, which cause the optical appearance of the manufactured three-dimensional object 2 to appear as if it were built up layer by layer according to conventional additive manufacturing methods. The corresponding light modulation device 11 thus has a positive influence on the properties (i.e., in particular the surface and / or volume properties) of the three-dimensional object 2 manufactured using the device 1.

[0111] Figures 2 to 14 A more specific embodiment of a corresponding light modulation device 11 is shown. Figures 2 to 14 yes Figure 1 A simplified diagram of the device 1 in the xy plane. It is worth noting that for ease of illustration, only the Figure 1 1 is the light source 4.1 on the left side of the first illumination device 4. However, all descriptions provided below are also applicable to the light source 4.1 on the right side of the first illumination device 4 (and possibly at least one other light source 4.1).

[0112] from Figures 2 to 14As is apparent from the exemplary embodiments of the present invention, the corresponding light modulation device 11 can include, for example, one or more optically transmissive elements and / or one or more optically reflective elements and / or one or more optically diffractive elements. Thus, the configuration of the corresponding light modulation device 11 can be configured to influence the spatial extension direction and / or orientation of the light beams of the light plane 8 based on one or more transmission effects and / or one or more reflection effects and / or one or more diffraction effects, thereby causing at least two light beams to extend in a non-parallel arrangement relative to one another, the one or more transmission effects and / or one or more reflection effects and / or one or more diffraction effects being caused by the one or more corresponding optically transmissive elements and / or one or more corresponding optically reflective elements and / or one or more corresponding optically diffractive elements. A non-limiting example of a corresponding optically transmissive element is an optical element including one or more optically transmissive surfaces, such as an optical lens. For example, the corresponding optically transmissive surface can be constructed from or include one or more optically transmissive coatings. A non-limiting example of a corresponding optically reflective element is an optical element including one or more optically reflective surfaces, such as an optical lens, a mirror, etc. For example, the corresponding optically reflective surface can be constructed from or include one or more optically reflective coatings. A non-limiting example of a corresponding optical diffraction element is an optical element comprising one or more optical diffraction surfaces, such as an optical lens, etc. For example, the corresponding optical diffraction surface may be constructed of or include one or more optical diffraction coatings.

[0113] Figures 2 to 14 The exemplary embodiment of specifically shows that the respective light modulation device 11 can be arranged in an optical path extending between the respective light source 4.1 of the first illumination device 4 and the working volume 3. Thus, the respective light modulation device 11 can be arranged upstream of the working volume 3. In other words, the respective light modulation device 11 can be arranged outside the working volume 3 and outside the container 6 comprising the working volume 3. In particular, the respective light modulation device 11 can be arranged before the entry point of the container 6, from which the plurality of light beams enter the container 6 to form the light plane 8 in the working volume 3. This arrangement of the respective light modulation device 11 outside the container 6 ensures that the respective light modulation device 11 does not correspondingly reduce the working volume 3 and the available build volume. Furthermore, the respective light modulation device 11 does not come into contact with the photopolymerizable material, so that any possible undesirable interactions between the photopolymerizable material and the respective light modulation device 11 or its components can be avoided.

[0114] exist Figure 2In the exemplary embodiment of the first illumination device 4, the first illumination device 4 comprises a generally optional collimator device 12, for example a collimating lens, which is configured to collimate the light, emitted from the respective light source 4.1 of the first illumination device 4, before the light enters the working volume 3. As an alternative to the respective collimator device 12, the first illumination device 4 can generally also comprise an objective lens device (this applies to all embodiments).

[0115] exist Figure 2 In an exemplary embodiment of the present invention, the light modulation device 11 further comprises a collimator device 12. As shown in the figure, the collimator device 12 can be moved relative to the container 6 with at least one degree of freedom of movement along at least one translation axis and / or around at least one rotation axis (e.g. Figure 2 Any movement of the collimator device 12 will result in a corresponding non-parallel arrangement of the light beams in the light plane 8.

[0116] In particular, the respective translation axes can be arranged, for example, parallel or non-parallel relative to an axis defining the transverse spatial extension of light plane 8. The non-parallel arrangement of the respective translation axes relative to an axis defining the transverse spatial extension of light plane 8 can include, for example, an arrangement at an angle (particularly perpendicular) relative to an axis defining the transverse spatial extension of at least one light plane. In other words, the respective translational motion can include an upward and / or downward movement of the collimator arrangement 12 relative to the light source 4.1 or the container 6. Additionally or alternatively, the respective degrees of freedom of movement can include a rotational movement of the collimator arrangement 12 about at least one rotational axis. The respective rotational axis can be arranged, for example, parallel or non-parallel relative to an axis defining the transverse spatial extension of light plane 8. The non-parallel arrangement of the respective rotational axis relative to an axis defining the transverse spatial extension of light plane 8 can include, for example, an arrangement at an angle (particularly perpendicular) relative to the axis defining the transverse spatial extension of light plane 8. In other words, the respective rotational motion can include a pivoting or tilting movement of the collimator arrangement 12 relative to the light source 4.1 or the container 6.

[0117] Similarly, the first illumination device 4 or at least one component thereof (in particular, the light source 4.1) can be supported so as to be movable in at least one degree of freedom of movement, in particular, so as to be movable in at least one degree of freedom of movement relative to the collimator device 12 or the container 6. Thus, the aforementioned effect of directing the light beam such that at least one light plane comprises a non-parallel and / or incoherent light beam can also be achieved or supported by moving the first illumination device 4 or at least one component thereof (in particular, relative to the collimator device 12 or the container 6). The corresponding degree of freedom of movement can include a translational movement of the first illumination device or at least one component thereof along at least one translation axis. The corresponding translation axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension of the light plane 8. The non-parallel arrangement of the corresponding translation axis relative to the axis defining the transverse spatial extension of the light plane 8 can include, for example, an arrangement at an angle (in particular, perpendicular) to the axis defining the transverse spatial extension of the light plane 8. In other words, the corresponding translational movement can include, for example, an upward and / or downward movement of the first illumination device 4 or at least one component thereof relative to the collimator device 12 or the container 6. Additionally or alternatively, the corresponding degree of freedom of movement can include a rotational movement of the first illumination device 4 or at least one component thereof about at least one rotational axis. The corresponding rotational axis can be arranged, for example, parallel or non-parallel to the axis defining the transverse spatial extension of the light plane 8. The non-parallel arrangement of the corresponding rotational axis relative to the axis defining the transverse spatial extension of the light plane 8 can include, for example, an arrangement at an angle (in particular perpendicular) to the axis defining the transverse spatial extension of the light plane 8. In other words, the corresponding rotational movement can include, for example, a pivoting movement of the first illumination device 4 or at least one component thereof relative to the collimator device 12 or the container 6.

[0118] from Figure 6As is apparent from the exemplary embodiments of FIG. 1 , the respective light modulation device 11 or at least one component thereof (e.g., a transmissive element and / or a reflective element and / or a diffractive element) can also be supported so as to be movable in at least one degree of freedom of movement, in particular relative to the respective light source 4 or relative to the working volume 3. Thus, the aforementioned effect of guiding the light beam such that the light plane 8 comprises non-parallel and / or incoherent light beams can also be achieved or supported by moving the at least one first light modulation device 11 or at least one component thereof (in particular relative to the light source 4.1 or the container 6). The respective degree of freedom of movement can include a translational movement of the first light modulation device 11 or at least one component thereof along at least one translation axis. The respective translation axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension of the light plane 8. The non-parallel arrangement of the respective translation axis relative to the axis defining the transverse spatial extension of the light plane 8 can include, for example, an arrangement at an angle (in particular, perpendicular) to the axis defining the transverse spatial extension of the light plane 8. In other words, the respective translational movement can include an upward and / or downward movement of the respective light modulation device or at least one component thereof relative to the light source 4.1 or the container 6. Additionally or alternatively, the respective degree of freedom of movement can include a rotational movement of at least one light modulation device 11 or at least one component thereof about at least one rotational axis. The respective rotational axis can be arranged, for example, parallel or non-parallel to an axis defining the transverse spatial extension of the light plane 8. The non-parallel arrangement of the respective rotational axis relative to the axis defining the transverse spatial extension of the light plane 8 can include, for example, an arrangement at an angle (in particular perpendicular) to the axis defining the transverse spatial extension of the light plane 8. In other words, the respective rotational movement can include a pivoting movement or a tilting movement of the respective light modulation device 11 or at least one component thereof relative to the light source 4.1 or the container 6.

[0119] Any movement of at least one of the at least one collimator device 12 (if present), the corresponding light modulator 11 or at least one component thereof, or the first illumination device 4 or at least one component thereof can be achieved by at least one drive device (not shown), such as an electric motor, an (electro)magnetic actuator, a piezoelectric actuator, etc., for example, the drive device is configured to generate a drive force to move at least one of the at least one collimator device 12, the corresponding light modulator 11 or at least one component thereof, or the first illumination device 4 or at least one component thereof in at least one corresponding degree of freedom of movement. Therefore, the corresponding drive device can be directly or indirectly coupled or connected to the at least one collimator device 12, the corresponding light modulator 11 or at least one component thereof, or the first illumination device 4 or at least one component thereof, so as to achieve movement of the at least one collimator device 12, the corresponding light modulator 11 or at least one component thereof, or the first illumination device 4 or at least one component thereof in at least one degree of freedom of movement. In an exemplary embodiment, each of the at least one collimator device 12, the corresponding light modulator 11 or at least one component thereof, or the first illumination device 12 or at least one component thereof includes at least one corresponding drive device.

[0120] The operation of at least one drive device can be controlled by at least one hardware and / or software-implemented control unit 15 of the apparatus 1 assigned to the drive device. The control unit 15 can be specifically configured to implement regular and / or irregular motion, in particular oscillatory and / or non-oscillatory motion, of the at least one collimator device 12, the corresponding light modulation device 11, or at least one component thereof, or the first illumination device 4, or at least one component thereof, in at least one degree of freedom of motion. The control unit 15 can be specifically configured to implement a motion profile of the at least one collimator device 12, the corresponding light modulation device 11, or at least one component thereof, or the first illumination device 4, or at least one component thereof, in one or more degrees of freedom of motion. Both regular and irregular motions can reduce corresponding streaking or graining effects and positively influence the surface and / or volumetric properties of the three-dimensional object 2 produced using the apparatus 1. In an exemplary embodiment, each of the at least one collimator device 12, the corresponding light modulation device 11, or at least one component thereof, and the first illumination device 4, or at least one component thereof, includes at least one corresponding drive device, and the operation of the corresponding drive devices can be controlled in a correlated or independent manner. In particular, the respective motion profiles may be achieved by correlated or independent control of the operation of respective drive means assigned to at least one collimator device 12, the respective light modulation device 11 or at least one component thereof and the first illumination device 4 or at least one component thereof.

[0121] exist Figure 3In the exemplary embodiment of FIG, it is shown that the respective light modulation device 11 can be arranged or constructed between the respective collimator device 12 and the working volume 3. Therefore, the respective light modulation device 11 can be arranged in the optical path of the light beam after the light beam passes through the collimator device 12 (downstream of the collimator device), so that the light passing through the collimator device 12 does not necessarily include at least two light beams that already have a non-parallel arrangement with respect to each other. In such a configuration, at least when there is no further light modulation device 11 in the upstream arrangement, the collimator device 12 does not necessarily affect the effect of guiding the light beam so that the light plane 8 includes non-parallel and / or incoherent light beams described above.

[0122] Thus, for example, a corresponding light modulation device 11 may be additionally or alternatively provided or constructed between the light source 4.1 and the collimator device 12. Thus, the corresponding light modulation device 11 may be additionally or alternatively arranged in the optical path of the light beam before (upstream of) the light beam passes through the collimator device 12, so that the light passing through the collimator device 12 may include at least two light beams that already have a non-parallel arrangement relative to one another. In such a configuration, the collimator device 12 may influence the above-described effect of directing the light beams so that the light plane 8 includes non-parallel and / or incoherent light beams.

[0123] exist Figure 3 In an exemplary embodiment of the invention, the light modulating device 11 is implemented as a diffuser device, in particular an elliptical diffuser device. In particular, the light modulating device 11 includes a plurality of optical elements (i.e. diffuser elements 16) arranged on one side of the base element 17. The optical elements form respective components of the light modulating device 11. Each optical element can be configured to change the original spatial extension direction and / or orientation of the incident light beam to generate a light beam having a different spatial extension direction and / or orientation relative to the original spatial direction and / or orientation. Therefore, each optical element can be configured to generate at least one light beam having a spatial extension direction and / or orientation adjusted relative to the original spatial extension direction and / or orientation. In particular, at least one optical element can be configured to generate a plurality of light beams, each light beam having a spatial extension direction and / or orientation adjusted relative to the corresponding original spatial extension direction and / or orientation. In this way, the respective optical elements can generate at least one light plane, the at least one light plane comprising two or more desired light beams arranged non-parallel to each other.

[0124] exist Figure 4In an exemplary embodiment of the invention, the light modulating device 11 is implemented as a microlens device. In particular, the light modulating device 11 includes a plurality of optical elements (i.e. microlens elements 18), in particular cylindrical microlens elements, arranged on one side of a base element 17. The optical elements form respective components of the light modulating device 11. Each optical element can be configured to change the original spatial extension direction and / or orientation of the incident light beam to generate a light beam having a different spatial extension direction and / or orientation relative to the original spatial direction and / or orientation. Therefore, each optical element can be configured to generate at least one light beam having a spatial extension direction and / or orientation adjusted relative to the original spatial extension direction and / or orientation. In particular, at least one optical element can be configured to generate a plurality of light beams, each light beam having a spatial extension direction and / or orientation adjusted relative to the corresponding original spatial extension direction and / or orientation. In this way, the respective optical element can generate at least one light plane, the at least one light plane comprising two or more desired light beams arranged non-parallel to each other.

[0125] Figure 3 、 Figure 4 and Figure 6 The two corresponding optical elements shown in the exemplary embodiment can be arranged in at least one row and / or at least one column. Therefore, the corresponding light modulation device 11 can include an arrangement of at least one row and / or at least one column of corresponding optical elements. Therefore, the corresponding optical elements can be arranged in a one-dimensional or multi-dimensional array, the array including at least one row and / or at least one column, at least one row including at least one optical element, and at least one column including at least one optical element.

[0126] exist Figure 3 、 Figure 4 and Figure 6 In the exemplary embodiment of the present invention, the optical elements are arranged or constructed on one side of the corresponding substrate element 17. Therefore, the light modulation device 11 includes at least one substrate element 17 having one or more corresponding optical elements arranged or constructed on at least one side thereof. The corresponding substrate element 17 may include a first side and a second side opposite to the first side. Figure 5 In an exemplary embodiment of the present invention, one or more optical elements are arranged or constructed on the first side and the second side of the base element 17. Therefore, in this embodiment, the light modulation device 11 can be implemented as a so-called cylindrical fly's eye concentrator.

[0127] For the sake of completeness, it is important to note that Figures 3 to 5The arrangement of the base element 17 and the corresponding optical elements attached thereto downstream of the collimator device 12 in the exemplary embodiment (generally optional) is merely an example. It is likewise conceivable to arrange the base element 17 and the corresponding optical elements attached thereto upstream of the collimator device 12. Thus, at least one corresponding base element 17 and the corresponding optical element or elements arranged or constructed on at least one side thereof can be arranged upstream or downstream of the corresponding collimator device 12, which is arranged in the optical path extending between the light source 4.1 of the first illumination device 4 and the container 6.

[0128] exist Figure 7 In an exemplary embodiment, the corresponding light modulation device 11 includes at least one first optical lens, in particular a plano-convex lens 19a or a free-form lens, arranged upstream of the light deflection device 9, and at least one second optical lens, in particular a plano-concave lens 19b or a free-form lens, arranged downstream of the light deflection device 9. The arrangement of the first optical lens upstream of the light deflection device 9 means that the first optical lens is arranged in the portion of the optical path extending between the light source 4.1 of the first illumination device 4 and the light deflection device 9. The arrangement of the second optical lens downstream of the light deflection device 9 means that the second optical lens is arranged in the portion of the optical path extending between the light deflection device 9 and the working volume 3. The first optical lens and its arrangement upstream of the light deflection device 12 are particularly useful for generating light with a line profile. The generation of light with a line profile is particularly useful in combination with the second optical lens, which is arranged between the light deflection device 9 and the (optional) collimator device 12, which is arranged upstream of the working volume 3.

[0129] exist Figure 8 and Figure 9 In an exemplary embodiment of the present invention, the corresponding light modulation device 11 comprises a beam steering device 20 arranged upstream of the light deflection device 9. The beam steering device 20 is configured to change the spatial extension direction and / or orientation of at least one light beam emitted by the light source 4.1 of the first illumination device 4 and directed towards the light deflection device 9 arranged upstream. Therefore, a desired non-parallel arrangement of at least two light beams relative to each other within the light plane 8 can also be achieved or supported by the beam steering device 20 arranged upstream of the light deflection device 9. The arrangement of at least one beam steering device upstream of the light deflection device 9 means that the beam steering device 20 is arranged in a portion of the optical path extending between the light source 4.1 of the first illumination device 4 and the light deflection device 9.

[0130] exist Figure 8In an exemplary embodiment, the light beam steering device 20 includes at least one optically transmissive element 21, such as a glass plate, which is movably supported with at least one degree of freedom of movement (exemplarily indicated by a double arrow). The light beam steering device 20 can be configured to change the spatial extension and / or orientation of at least one light beam emitted from the light source 4.1 of the first illumination device 4 and directed toward the light deflection device 9 by one or more movements of the at least one optically transmissive element 21 in the at least one degree of freedom of movement. The respective degrees of freedom of movement can be or include a translational movement of the at least one optically transmissive element 21 along a translation axis and / or a rotational movement of the at least one optically transmissive element 21 about a rotational axis, such as a pivoting movement or a tilting movement. The movement of the at least one optically transmissive element 21 can be synchronized with the rotational movement of the base body 9.2 of the light deflection device 9 by at least one hardware and / or software-implemented control unit 15, which can be configured to control the movement of the at least one optically transmissive element 21 and the base body 9.2.

[0131] exist Figure 9 In an exemplary embodiment, the light beam steering device 20 includes at least one optical reflective element 22, such as a mirror, which is supported in a movable manner with at least one degree of freedom of movement (as exemplarily indicated by a double arrow). The light beam steering device 20 can be configured to change the spatial extension direction and / or orientation of at least one light beam emitted from the light source 4.1 of the first illumination device 4 and directed toward the light deflection device 9 by one or more movements of the at least one optical reflective element 22 in at least one degree of freedom of movement. The corresponding degrees of freedom of movement can be or include a translational movement of the at least one optical reflective element 22 along a translation axis and / or a rotational movement of the at least one optical reflective element 22 about a rotation axis, such as a pivoting movement or a tilting movement. The movement of the at least one optical reflective element 22 can be synchronized with the rotational movement of the base body 9.2 of the light deflection device 9 by at least one hardware and / or software-implemented control unit 15, which can be configured to control the movement of the at least one optical reflective element 22 and the base body 9.2.

[0132] exist Figure 10 In an exemplary embodiment of the present invention, a corresponding beam steering device 20 is arranged downstream of the light deflecting device 9. The beam steering device 20 is configured to change the spatial extension direction and / or orientation of at least one light beam emitted by the light source 4.1 of the first illumination device 4 and directed towards the working volume 3 arranged downstream. Therefore, a desired non-parallel arrangement of at least two light beams relative to each other within the light plane 9 can also be achieved or supported by the beam steering device 20 arranged downstream of the light deflecting device 9. The arrangement of at least one beam steering device downstream of the light deflecting device 9 means that the beam steering device 20 is arranged in the section of the optical path extending between the light deflecting device 9 and the working volume 3.

[0133] exist Figure 10 In an exemplary embodiment, the light beam steering device 20 includes at least one optical reflective element 22, such as a mirror, which is movably supported with at least one degree of freedom of movement (as exemplarily indicated by a double arrow). The light beam steering device 20 can be configured to change the spatial extension direction and / or orientation of at least one light beam emitted from the light source 4.1 of the first illumination device 4 and directed toward the light deflection device 9 by one or more movements of the at least one optical reflective element 22 in at least one degree of freedom of movement. The corresponding degrees of freedom of movement can be or include a translational movement of the at least one optical reflective element 22 along a translation axis and / or a rotational movement of the at least one optical reflective element 22 about a rotation axis, such as a pivoting movement or a tilting movement. The movement of the at least one optical reflective element 22 can be synchronized with the rotational movement of the base 9.2 of the light deflection device 9 by at least one control unit 15 implemented by hardware and / or software. The control unit 15 can be configured to control the movement of the at least one optical reflective element 22 and the base 9.2.

[0134] exist Figure 11 In an exemplary embodiment of the light modulation device 11, the light modulation device 11 comprises an adaptive optical element 23 having an adaptive shape and therefore a variable shape. Adaptive and therefore variable shape means that the adaptive optical element 23 can change its geometric dimensions (e.g. its length and / or width and / or height, in particular relative to a reference state) in at least one spatial direction. Thus, the adaptive optical element 23 can be configured to change the spatial extension direction and / or orientation of at least one light beam by one or more adaptive changes or variations of its shape. Figure 11 As shown, the adaptive optical element 23 can be arranged in particular downstream of the deflection device 9 and downstream of the corresponding collimator device 12 (if present). The adaptive optical element 23 can be particularly configured to dynamically change the focal length of the light beam incident into the working volume 3 based on a corresponding change in its shape. A control unit 15 implemented by hardware and / or software can be assigned to the adaptive optical element 23. The control unit 15 can be configured to control the change and / or variation of the shape of the adaptive optical element 23.

[0135] The adaptive optical element 23 may be constructed as or include an adaptive optical transmission element or an adaptive optical reflection element. The adaptive optical transmission element is particularly an adaptive lens, more particularly a liquid lens, and the optical reflection element is particularly an adaptive mirror, more particularly a liquid mirror.

[0136] exist Figure 12In an exemplary embodiment, the light modulation device 11 includes one or more optical modulation elements 24 attached to an outer surface of the base body 9.2 of the light deflecting device 9. In particular, each respective optical modulation element 24 can be attached to an outer surface of a respective light deflecting element 9.1 on the outer surface of the base body 9.2. The respective optical modulation element 24 can be a refractive element, such as a glass element, which can achieve a desired non-parallel arrangement of the at least two light beams in the light plane 8.

[0137] exist Figure 13 In an exemplary embodiment, the light modulation device 11 includes a one-dimensional or multi-dimensional surface structure 25 on the outer surface of the substrate 9.2 of the light deflecting device 9. The corresponding one-dimensional or multi-dimensional surface structure 25 of the outer surface of the substrate 9.2 can include a specific arrangement of reflective and / or refractive elements on the outer surface of the substrate 9.2, for example, an alternating arrangement. The corresponding reflective and / or refractive elements can have the same shape or different shapes. As an example, the corresponding one-dimensional or multi-dimensional surface structure of the outer surface of the substrate 9.2 can include a specific arrangement of reflective and / or refractive elements having a convex, concave, cylindrical, polygonal shape, etc., for example, an alternating arrangement of reflective and / or refractive elements having a convex, concave, cylindrical, polygonal shape, etc. Additionally or alternatively, the corresponding one-dimensional or multi-dimensional surface structure of the outer surface of the substrate 9.2 can include chemical and / or physical modifications to the surface of the light deflecting elements 9.1 on the outer surface of the substrate 9.2. The corresponding chemical and / or physical modification can be achieved by a deposition process, in which at least one optically effective deposition material is deposited on at least one light deflection element 9.1 to adjust its optical properties; by an etching process, the surface of at least one light deflection element 9.1 is etched to adjust its optical properties, and so on.

[0138] exist Figure 14 In an exemplary embodiment of the present invention, the light modulation device 11 comprises an exemplary relative arrangement of a plurality of optical reflective elements 27 (e.g. mirrors), each of which has a surface that is tilted relative to the initial spatial extension direction of the light beam that has passed through the optional collimator device 12. The tilted surfaces 27.1 of the optical reflective elements 27 are configured to change the spatial extension direction and the orientation of the spatial extension direction of the incident light beam by reflection, respectively, so that the light beam intersects other light beams in the working volume 3.

[0139] It is worth noting that at least one respective optical reflective element 27 can be supported in a movably manner in at least one degree of freedom of movement, for example in a rotational degree of freedom of movement, as indicated above in other embodiments, the corresponding descriptions applying here in an analogous manner.

[0140] In any embodiment, it is also conceivable that the container 6 is supported in a movable manner in at least one degree of freedom of movement, for example relative to the at least one light source 4.1 of the first illumination device 4.1, for example due to a refractive effect of the material forming the container walls 6.2-6.5, so as to achieve or support a desired non-parallel arrangement of the at least two light beams in the light plane 8. As further indicated above, at least some of the container walls 6.2-6.5 can achieve at least a certain degree of refractive effect, so that movement of the container 6 in at least one degree of freedom of movement can achieve or support a desired non-parallel arrangement of the at least two light beams in the light plane 8.

[0141] In any embodiment, the apparatus 1 may include a determination device 26 configured to determine surface and / or volume characteristics of a three-dimensional object 2 manufactured using the apparatus. The determination device 26 may include a detection unit 26.1, such as an optical detection unit, such as a camera, configured to detect information indicating surface and / or volume characteristics of the three-dimensional object 2 manufactured using the apparatus 1. This information indicating the surface and / or volume characteristics of the three-dimensional object manufactured using the apparatus 1 may be transmitted to the control unit 15, which may be configured to control the operation of the light modulation device 11. In this way, a process control loop may be implemented. This is particularly applicable when the corresponding information indicating the surface and / or volume characteristics of the three-dimensional object 2 manufactured using the apparatus 1 is used to perform online control of the operation of at least one light modulation device 11.

[0142] Even if not explicitly shown in the figures, the light modulation device or at least one light modulation device 11 can be configured to generate incoherent light. Thus, the respective light modulation device 11 can include an incoherent light source (e.g., a light emitting diode) configured to generate incoherent light and / or an optical light guide (e.g., an optical fiber) configured to modify the properties of coherent light to thereby obtain incoherent light. The incoherent light can include corresponding intersecting light beams, thereby achieving a desired light beam intersection in the working volume 3.

[0143] Each exemplary device 1 shown in the figures is capable of implementing a volumetric 3D printing method to form a three-dimensional object 2. The method comprises at least the following steps: generating a first light projection 7 in a working volume 3 by means of a first illumination device 4, the first illumination device 4 being configured to irradiate light L1 of a first wavelength into the working volume 3 containing a photopolymerizable material (in particular a photopolymerizable polymer resin), the first light projection 7 comprising a plurality of light beams passing through the working volume 3 in a light plane 8; and modulating, by means of at least one light modulator 11 assigned to the first illumination device 4, the spatial extension direction of two or more of the plurality of light beams in the light plane 8, such that the two or more light beams extend in a non-parallel arrangement relative to each other.

[0144] Preferably, the method is performed using light of at least two different wavelengths, wherein a first wavelength is used to generate or project the corresponding light plane 8, and an additional wavelength is used to generate or project the corresponding image of the cross section of the three-dimensional object 2 to be constructed. The first wavelength is typically smaller than the additional wavelength. Thus, the method preferably implements the so-called two-color photopolymerization principle.

[0145] Figure 15 Example experimental results showing properties of an object manufactured according to an exemplary embodiment (lower graph) and properties of a reference object not manufactured according to an exemplary embodiment (upper graph) are shown. The test results are related to measured surface properties that indicate the surface roughness of the corresponding object.

[0146] The figure clearly shows that the object manufactured according to the exemplary embodiment (ie, by using the light modulation device 11 ) has a smoother surface profile than the surface profile of a reference object manufactured by a similar volumetric printing process but without using the light modulation device 11 .

[0147] Both objects are formed by photopolymerizing a liquid photopolymerizable material having the following composition:

[0148] Polyurethane methacrylate oligomer 70wt% Acryloylmorpholine (ACMO) 25wt% N-Methyldiethanolamine (MDEA) 5wt% Dual-color photoinitiator (spiropyran-based) 0.02wt%

[0149] The reference object was a rectangular parallelepiped (dimensions x, y, z: 7 x 14 x 1 mm). After printing, the reference object was removed from the container and immersed in a bath containing tripropylene glycol monomethyl ether (TPM) for 5 minutes. The reference object was removed from the bath, washed with ethanol to remove the remaining TPM, and then the reference object was air-dried for 10 minutes. Finally, the reference object was placed in a UV-LED chamber (375 nm) for post-curing for 6 minutes. No further surface conditioning of the reference object was performed. Visual inspection of the printed and post-cured reference object revealed strong streaking artifacts in the form of dense parallel lines visible to the naked eye on the surface and within the bulk of the cured material.

[0150] The objects manufactured according to the exemplary embodiment were also cuboids (dimensions x, y, z: 7 x 14 x 1 mm). After printing, the objects were removed from the container and placed in a bath containing tripropylene glycol monomethyl ether (TPM) for 5 minutes. The objects were removed from the bath, the remaining TPM was washed off with ethanol, and then the objects were dried in air for 10 minutes. Finally, the objects were placed in a UV-LED chamber (375 nm) for post-curing for 6 minutes. No further surface conditioning of the objects was performed. Visual inspection of the printed and post-cured objects revealed smooth, optically clear, and volumetrically uniform surfaces without any defects or streak artifacts visible to the naked eye.

[0151] The reference and object samples were analyzed using a Keyence VK-X3000 confocal laser scanning microscope. Surface roughness was determined according to ISO 4287 by averaging 11 profile lines along the object surface, with a cutoff wavelength of λc = 0.25 mm. The values ​​and standard deviations obtained are as follows:

[0152]

[0153] Experiments have shown that due to the use of the light modulation device 11 as described above, the properties of the printed and post-cured object (ie the surface roughness) are reduced by more than a factor of 10 compared to a reference object.

[0154] Figure 16 A schematic diagram of a device 1 for volumetric 3D printing of at least one three-dimensional object according to an additional exemplary embodiment is shown.

[0155] Figure 16 The exemplary embodiment of FIG. 1 first shows an exemplary embodiment of a first illumination device 4 comprising four light sources 4.1, each configured to generate a light sheet of light of a first wavelength L1 and illuminate the light sheet into the working volume 3. The plurality of individual light sheets extend through the working volume 3 at one or more different angles relative to one another and overlap in at least one light sheet overlap region within the working volume 3. The plurality of individual light sheets can form a composite light sheet within the working volume 3.

[0156] Additionally or alternatively, each individual light sheet includes a main extension direction through the working volume. Thus, the at least one first illumination device 4 can be configured to generate a plurality of individual light sheets, wherein the respective individual light sheets extend through the working volume with their main extension directions at one or more different angles relative to one another. The main extension directions of the individual light sheets typically intersect in at least one light sheet overlap region.

[0157] In particular, the first illumination device 4 can be configured to generate four separate light sheets, wherein at least a first separate light sheet extends through the photocurable resin at a first angle, a second separate light sheet extends through the photocurable resin at an angle of approximately 90° relative to the first separate light sheet, a third separate light sheet extends through the photocurable resin at an angle of approximately 90° relative to the second separate light sheet, and a fourth separate light sheet extends through the photocurable resin at an angle of approximately 90° relative to the third separate light sheet, resulting in the separate light sheets being arranged in a cross shape.

[0158] Figure 16The exemplary embodiment also includes a support structure 30 that supports an optical element, such as a lens element 18 of the light modulation device 9, in particular a microlens element, or an array of lens elements 18 or microlens elements. The support structure 30 is arranged to respectively surround the working volume 3 and the corresponding container 6 that delimits the working volume 3. Thus, the support structure 30 can define a receiving space 31, such as a cylindrical or polygonal receiving space, for respectively receiving the working volume 3 and the corresponding container 6. Thus, the support structure 30 can have a basic shape, such as a hollow cylinder or a polygon. The support structure 30 can have an open portion 32 (opening), such as an open lower portion, that enables the insertion and removal of the corresponding container 6. Providing the support structure 30 is particularly advantageous for embodiments in which the at least one first illumination device 4 is configured to generate a plurality of individual light sheets, in particular four individual light sheets, that extend through the working volume 3 at at least one or more different angles relative to one another, thereby enabling the generation of a composite light sheet having desired properties.

[0159] The support structure 30 can be at least partially transparent to light of the first and / or second wavelengths. In particular, the support structure 30 can be transparent to the light of the first and / or second wavelengths L1, L2 at the portion where the light of the first and / or second wavelengths L1, L2 enters the working volume 3 enclosed by the support structure 30. Therefore, the support structure 30 can be at least partially made of glass or a transparent polymer material, such as PC (polycarbonate), PMMA (polymethyl methacrylate), or COC (cyclic olefin copolymer).

[0160] The supporting structure 30 may include one or more non-reflective surfaces to avoid undesirable optical effects based on reflection of light of at least the first wavelength. Corresponding non-reflective surfaces may be provided on the top and / or side of the supporting structure 30. For example, the corresponding non-reflective surfaces may be made of a non-reflective material. As an example, the supporting structure 30 may include a flexible element, such as a foil, in particular a foil having one or more non-reflective surfaces. Specific examples are lens foils or lens sheets.

[0161] The support structure 30 can be rotatably supported about a rotation axis A. The rotation axis A is, in particular, parallel to the central axis of the working volume 3 and / or perpendicular to the rotation axis extending along the corresponding light sheet. The support structure 30 can be assigned at least one support device 35 to support the support structure 30 and maintain its orientation and / or position relative to the rotation axis A and the working volume 3. The at least one support device 35 can include one or more support elements 35.1, such as bearings, which are directly or indirectly connected to the support structure. In particular, at least three support elements 35.1 can be provided, preferably evenly spaced along the circumference of the support structure 30. Furthermore, the support structure 30 can be assigned at least one drive device 36 (e.g., an electric motor) to generate a force or momentum to rotate the support structure 30 about the rotation axis A. The at least one drive device 36 can include one or more drive elements 36.1 (e.g., gears), which can be connected or coupled to the support structure 30 to transmit the corresponding force or momentum to the support structure 30. The at least one drive device 36 may also form part of the support device 35 and vice versa. Thus, embodiments are conceivable in which the drive device 36 transmits force or momentum to the carrier structure 30 via one or more gears and / or one or more bearings.

[0162] The supporting structure 30 and / or the working volume and / or the corresponding container 6 defining the working volume can be supported in a movable manner relative to each other. As an example, the supporting structure 30 can be supported in a movable manner on a Figure 16 In at least one operative position shown, in the at least one operative position, the support structure 30 is positioned relative to the working volume 3 and the respective container 6 such that the support structure 30 surrounds the working volume 3 and the respective container 6, and the support structure 30 can be supported in a movable manner in at least one inoperative position, in the at least one inoperative position, the support structure 30 is positioned relative to the working volume 3 and the respective container 6 such that the support structure 30 does not surround the working volume 3 and the container 6. In this way, a conversion structure 37 can be assigned to the support structure 30, which conversion structure 37 is configured to convert the support structure 30 into the at least one operative position and the inoperative position, respectively.

[0163] Figure 17 and Figure 18 Both show principle diagrams of an apparatus 1 for volumetric 3D printing of at least one three-dimensional object according to additional exemplary embodiments.

[0164] Figure 17 and Figure 18It is generally shown that the light modulation device 9 can be configured to generate one or more points in the working volume 3 or at least one forming area, and to extend the light beam of the first wavelength through the one or more points based on at least one of the following speckle reduction principles: angular diversity (such as Figures 1 to 16 ), polarization diversity and wavelength diversity. Figure 17 As shown, the light modulation device 9 can be configured to generate at least two light beams of a first wavelength having different polarizations or polarization states (polarization diversity) at at least one point within the working volume 3, and / or as shown Figure 18 As shown, at least two light beams with different wavelengths (in particular within a specific wavelength range) are generated at at least one point within the working volume 3 (wavelength diversity).

[0165] Figure 17 Specifically illustrating the principle of polarization diversity, the method can include generating or using at least two light beams of at least a first wavelength, which have different polarizations or polarization states, in particular two orthogonal polarization states, at at least one point within the working volume 3 or formation area. In particular, at least one of the at least two light beams can be incoherent, for example, generated by an optical fiber 40 or at least two different light sources. The corresponding different polarizations or polarization states can include, for example, different linear polarizations or different circular polarizations. In such an embodiment, the light modulation device 9 can include at least one optical fiber 40, at least one polarization element 41 (e.g., a polarization filter, in particular, a polarization filter rotatable about an axis of rotation, which can be or include the axis of the light beam emitted by the light source 4.1 of the first wavelength), a beam expansion device 42 (configured to expand the incident light beam, for example, to generate a light sheet or a linear beam cross section or beam profile), and at least one collimating element 43 (e.g., a collimating lens).

[0166] Figure 18Specifically illustrating the principle of wavelength diversity, the method can include generating or using at least two light beams of a first wavelength, each of which has a different wavelength at at least one point within the working volume 3 or formation area. In particular, a broadband light source in combination with an optical filter 44 (e.g., a bandpass filter with different angles of incidence) can generate the different wavelengths. The different wavelengths can be, for example, wavelengths in the range of 350 nm to 500 nm, particularly 375 nm to 450 nm, more particularly 385 nm to 440 nm, more particularly 395 nm to 420 nm, and even more particularly 400 nm to 410 nm. In such an embodiment, the light modulation device 9 may include at least one optical filter element 44, a beam expansion device 42 and at least one collimating element 43, the optical filter element 44 being, for example, a bandpass filter, in particular a bandpass filter movable in at least one degree of freedom of movement, for example rotatable or tiltable about a rotation axis or a tilt axis, which may be or include the axis of the light beam emitted by the light source 4.1 of the first wavelength, the beam expansion device 42 being configured to expand the incident light beam, for example to generate a light sheet or a linear beam cross section or beam profile accordingly, and the collimating element 43 being, for example, a collimating lens.

[0167] One, several or all features of a particular exemplary embodiment of the device 1 may be combined with one, several or all features of at least one further exemplary embodiment of the device 1 .

Claims

1. An apparatus for volumetric 3D printing to form a three-dimensional object, the apparatus comprising: - a working volume configured to receive a photopolymerizable material, in particular a photopolymerizable polymer resin, which is illuminated by light to form a three-dimensional object; - at least one first illumination device configured to illuminate light of a first wavelength into the working volume to generate at least one first light projection in the working volume, the at least one first light projection comprising a plurality of light beams passing through the working volume in at least one light plane; - at least one light modulator device assigned to the at least one first illumination device, the at least one light modulator device being configured to modulate the spatial extension direction of two or more of the plurality of light beams in at least one light plane, so that the two or more light beams extend in a non-parallel arrangement relative to each other, and / or to generate at least two light beams with a first wavelength having different polarizations or polarization states at at least one point in the working volume, and / or to generate at least two light beams with different wavelengths at at least one point in the working volume, the wavelength being in particular within a specific wavelength range.

2. The apparatus according to claim 1, wherein the at least one light modulation device is configured to modulate the spatial extension direction of the two or more light beams in a common light plane so that the two or more light beams intersect at one or more points in the common light plane.

3. Apparatus according to claim 1 or 2, wherein the at least one light modulation device comprises one or more optically transmissive elements and / or one or more optically reflective elements and / or one or more optically diffractive elements.

4. An apparatus according to any of the preceding claims, wherein the at least one first illumination device comprises at least one first light source configured to generate light of a first wavelength, wherein the at least one light modulation device is arranged in an optical path between the light source of the at least one first illumination device and the working volume.

5. An apparatus according to any one of the preceding claims, wherein the at least one first illumination device comprises at least one first light source configured to generate light of a first wavelength, and further comprises a collimator device or an objective device, wherein the at least one light modulator is arranged in an optical path between the light source of the at least one first illumination device and the working volume, wherein the at least one light modulator is arranged or constructed between the at least one first light source and the collimator device or the objective device, and / or the at least one light modulator is arranged or constructed between the at least one collimator device or the objective device and the working volume.

6. An apparatus according to any of the preceding claims, wherein the at least one light modulation device or at least one component thereof is supported in a movable manner in at least one degree of freedom of movement, in particular is supported in a movable manner in at least one degree of freedom of movement relative to at least one light source of the at least one first illumination device or relative to the working volume.

7. Apparatus according to any of the preceding claims, wherein the at least one first irradiation device or at least one component thereof, in particular the first light source, is supported in a movable manner in at least one degree of freedom of movement, in particular is supported in a movable manner in at least one degree of freedom of movement relative to a working volume, in particular is supported in a movably manner in at least one degree of freedom of movement relative to a container comprising the working volume.

8. An apparatus according to any of the preceding claims, wherein the at least one light modulation device comprises one or more optical elements, each optical element being configured to change an original spatial extension direction of an incident light beam to generate a light beam having a spatial extension direction different from the original spatial extension direction. 9 . The device according to claim 8 , wherein the optical element is designed as or comprises an optical lens and / or an optical diffuser element, the optical lens being in particular a microlens and the optical diffuser element being in particular an elliptical diffuser element.

10. The device according to claim 8 or 9, wherein the optical elements are arranged in at least one row and / or at least one column.

11. Apparatus according to any one of claims 8 to 10, wherein the one or more optical elements are arranged or constructed on at least one side of a substrate element, which is arranged in the optical path upstream of the working volume, in particular upstream or downstream of a corresponding collimator device.

12. An apparatus according to any of the preceding claims, comprising a collimator device, which is configured to collimate the light emitted from at least one first light source before it enters the working volume, wherein the at least one light modulation device comprises at least one optical lens arranged upstream of the collimator device, the at least one optical lens being in particular a plano-concave lens or a free-form lens.

13. An apparatus according to any one of the preceding claims, comprising at least one light deflecting device, wherein the at least one light deflecting device is configured to deflect light emitted from the first light source or at least one first light source of the at least one first irradiation device to a working volume, in particular to a collimator device arranged upstream of the working volume, wherein the at least one light modulation device comprises at least one optical lens arranged upstream of the light deflecting device, the at least one optical lens being in particular a plano-convex lens or a free-form surface lens.

14. An apparatus according to any one of the preceding claims, comprising at least one light deflecting device, which is configured to deflect light emitted from the first light source or at least one first light source of the at least one first irradiation device to a working volume, in particular to a collimator device arranged upstream of the working volume, wherein the at least one light modulation device comprises at least one beam steering device arranged upstream of the light deflecting device, and the at least one beam steering device is configured to change the spatial extension direction of a light beam emitted from the at least one first light source and toward the beam steering device.

15. An apparatus according to claim 14, wherein the at least one light beam steering device comprises at least one optically transmitting element, which is supported in a movable manner in at least one degree of freedom of movement, and wherein the light beam steering device is configured to change the spatial extension direction of the light beam emitted from the at least one first light source and toward the light beam steering device through one or more movements of the at least one transmitting element in at least one degree of freedom of movement.

16. An apparatus according to claim 14 or 15, wherein the at least one light beam steering device comprises at least one optical reflective element, which is supported in a movable manner in at least one degree of freedom of movement, and wherein the light beam steering device is configured to change the spatial extension direction of the light beam emitted from the at least one first light source and toward the light beam steering device through one or more movements of the at least one transmitting element in at least one degree of freedom of movement.

17. An apparatus according to any of the preceding claims, wherein the at least one light modulation device comprises at least one adaptive optical element having an adaptive shape, wherein the at least one adaptive optical element is configured to change the spatial extension direction of the spatial extension of the light beam by one or more changes in its shape.

18. The device according to claim 17, wherein at least one adaptive optical element having a variable shape is constructed as or includes an adaptive optical transmission element or an adaptive optical reflection element, the adaptive optical transmission element is in particular an adaptive lens, more in particular a liquid lens, and the optical reflection element is in particular an adaptive mirror, more in particular a liquid mirror.

19. Apparatus according to any of the preceding claims, wherein the at least one light modulation device comprises a collimator device, the collimator device being supported in a movably manner with at least one degree of freedom of movement.

20. An apparatus according to any of the preceding claims, comprising at least one light deflecting device, wherein the at least one light deflecting device is configured to deflect light emitted from the first light source or at least one first light source of the at least one first illumination device to a working volume, in particular to a collimator device arranged upstream of the working volume, wherein the at least one light deflecting device comprises a substrate, wherein the at least one light modulation device comprises at least one optical element attached to an outer surface of the substrate.

21. An apparatus according to any of the preceding claims, comprising at least one light deflecting device, wherein the at least one light deflecting device is configured to deflect light emitted from the first light source or at least one first light source of at least one first irradiation device to a working volume, in particular to a collimator device arranged upstream of the working volume, wherein the at least one light deflecting device comprises a substrate, wherein the at least one light modulation device comprises a surface structure of an outer surface of the substrate.

22. The apparatus according to any of the preceding claims, further comprising a second illumination device, which is configured to illuminate light of a second wavelength into the working volume to generate a second light projection in the working volume, wherein the second light projection intersects the first light projection at a specific angle, in particular an angle of 45° or 90°.

23. Apparatus according to any preceding claim, wherein the working volume is provided by at least one container means defining a container volume for receiving a photopolymerisable material.

24. An apparatus according to any one of the preceding claims, further comprising a determining device configured to determine surface characteristics and / or volume characteristics of a three-dimensional object manufactured using the apparatus, wherein the determining device comprises a detection unit configured to detect information indicating surface characteristics and / or volume characteristics of a three-dimensional object manufactured using the apparatus; wherein the information indicating surface characteristics and / or volume characteristics of a three-dimensional object manufactured using the apparatus can be transmitted to a control unit of the apparatus, and the control unit is configured to control the operation of at least one light modulation device based on the information.

25. An apparatus according to any of the preceding claims, wherein the at least one light modulation device is configured to generate one or more points within at least one forming area and to extend a light beam of a first wavelength through the one or more points based on at least one of the following speckle reduction principles: angle diversity, polarization diversity, and wavelength diversity.

26. A method for volumetric 3D printing to form a three-dimensional object, the method comprising: - generating a first light projection in the working volume by at least one first illumination device, the at least one first illumination device being configured to illuminate light of a first wavelength into the working volume comprising a photopolymerizable material, in particular a photopolymerizable polymer resin, the first light projection comprising a plurality of light beams passing through the working volume in a common plane; and - Modulating the spatial extension direction of two or more of the plurality of light beams in at least one light plane by at least one light modulation device assigned to the at least one first illumination device so that the two or more light beams extend in a non-parallel arrangement relative to each other.

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