3D printing device for photopolymerizing a photosensitive resin through an exposure pattern

Abstract

3D printing device (10) for photopolymerizing a photosensitive synthetic resin (14) by an exposure pattern, comprising - a resin bath (12) for the photosensitive resin (14) with a lifting device (34), wherein the photosensitive resin (14) is polymerizable as a cured body on the lifting device (34) by means of light of a predetermined wavelength, and wherein the lifting device (34) is designed to move the cured body up and out of the resin bath (12) in order to change an exposure plane for the photosensitive resin with respect to the body; - a carrier medium (20) which is designed to transmit coupled-in light as a light guide by means of internal reflection, and having a coupling-in region (22) and a coupling-out region (24) which are arranged in different sections of the carrier medium; - an illumination device (18) which is designed to radiate the light onto the coupling region (22); wherein - the coupling-in region (22) has a coupling-in deflection structure (30) which is designed to couple light with the predetermined wavelength, which falls from the illumination device (18) onto the coupling-in deflection structure (30), into the carrier medium (20) in the direction of the coupling-out region (24); wherein - the coupling-out region (24) is arranged below the synthetic resin bath (12) and has a coupling-out deflection structure (32) which is designed and arranged to couple the coupled-in light with the predetermined wavelength, which falls on the coupling-out deflection structure (32), as an exposure pattern from the carrier medium (20) onto the photosensitive synthetic resin (14) of the synthetic resin bath for photopolymerization of the synthetic resin - wherein the input coupling deflection structure (30) and the output coupling deflection structure (32) are designed as an interference structure, grating structure, lens system or mirror.

Description

[0001] The invention relates to a 3D printing device for photopolymerizing a photosensitive resin by an exposure pattern.

[0002] There are known 3D printing processes in which a projector can project light from below onto a resin bath with a translucent base, curing the resin in the illuminated areas according to the projector's exposure pattern. In a so-called "Continuous Liquid Interface Production" (CLIP) process, the cured resin can be gradually drawn upwards, allowing resin to flow into the resulting gap at the bottom, which can then be exposed. In this way, a layered resin model can be created step by step.

[0003] From WO 2018 / 039688 A1 a method for solidifying a photopolymerizable, diffusely reflecting material by irradiation is known, wherein the irradiation of a surface to be solidified takes place through a transparent material boundary element into the material.

[0004] From US 2019 / 0111622 A1 a method and a device for forming a three-dimensional object from a liquid polymer is known.

[0005] A disadvantage of previously known CLIP processes is that the projector must be at a distance from the resin bath in order to expose a large area of ​​the resin bath, which requires more space.

[0006] The invention is based on the object of providing a space-saving 3D printing device.

[0007] The problem is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are disclosed by the dependent patent claims, the following description, and the figures.

[0008] The invention provides a 3D printing device for photopolymerizing a photosensitive resin by means of an exposure pattern. A photopolymer, such as polypropylene or polyurethane, can be used as the resin, for example. The 3D printing device comprises a resin bath for the photosensitive resin and a lifting device, wherein the photosensitive resin can be polymerized as a cured body on the lifting device using light of a predetermined wavelength, in particular ultraviolet light, and wherein the lifting device is designed to move the cured body out of the resin bath, for example stepwise or continuously, in order to change an exposure plane of the photosensitive resin. The resin bath can preferably have a transparent bottom through which light, in particular UV light, can shine. Quartz glass, in particular, can be used for this purpose.

[0009] The 3D printing device further comprises a carrier medium configured to transmit coupled light by means of internal reflection as a light guide. The 3D printing device has a coupling region and a coupling-out region arranged in different sections of the carrier medium. The carrier medium thus supports the coupling-in region and the coupling-out region. It is also a light-conducting medium. Furthermore, an illumination device configured to radiate the light onto the coupling-in region is provided.

[0010] The coupling-in region has an input deflection structure designed to couple light with the specified wavelength, which falls from the illumination device onto the input deflection structure, into the carrier medium in the direction of the output coupling region. The output coupling region is arranged below the synthetic resin bath and has an output deflection structure designed and arranged to couple the input light with the specified wavelength, which falls onto the output deflection structure, out of the carrier medium as an exposure pattern onto the photosensitive synthetic resin of the synthetic resin bath for photopolymerization of the synthetic resin. The input deflection structure and the output deflection structure are designed as an interference structure, grating structure, lens system, or mirror.

[0011] In other words, an illumination device, which may comprise, for example, a UV lamp or a UV light source, can emit light with a predetermined wavelength onto a coupling-in region of a carrier medium, wherein a coupling-in deflection structure of the coupling-in region can couple the light into a carrier medium. In the carrier medium, the light can then be guided to the said coupling-out region by means of internal reflection, i.e., by means of total internal reflection. At an output deflection structure of the output region, the light can be coupled out through a translucent base of the synthetic resin bath onto a photosensitive synthetic resin.

[0012] The photosensitive resin thus exposed can polymerize, i.e., harden, due to the light. The resulting hardened body can preferably harden on the underside of a lifting device. The lifting device can then move upwards by a predetermined distance or at a predetermined speed and / or by a predetermined increment, whereby a gap can form between the hardened body and the bottom of the resin bath, into which new resin can flow for photopolymerization. The resin that has flowed into the gap can then be re-exposed to light, gradually creating a 3D print according to an exposure pattern of the lighting device.

[0013] The input-coupling deflection structure and the output-coupling deflection structure can be designed as a diffraction structure or refraction structure, as an interference structure, a grating structure, a lens system, or a mirror. In particular, the input-coupling deflection structure and the output-coupling deflection structure can each be designed as a holographic optical element (HOE) (or holographic element for short), which can deflect light with a given wavelength at a given angle.

[0014] The lifting device can be designed as a platform sunk into the resin bath, which can be connected, for example, via a rail and / or a cable to an electric motor that can pull the platform step by step or continuously out of the resin bath. The platform can be located in an initial position close to the bottom of the resin bath, such that a gap exists between the platform and the bottom, in which gap the resin to be exposed can be located. Upon exposure, the resin located in the gap can polymerize; in particular, a layer of the resin can bond to the underside of the platform, such that when the platform is pulled out, the polymerized resin is pulled out with it.

[0015] The invention offers the advantage that a projection area in the resin bath can be enlarged by distributing the light across the carrier medium, without having to increase the distance between the lighting device or a projector and the resin bath. This allows a printing area or exposure area of ​​the 3D printing device to be enlarged without requiring additional installation space for optical components that would otherwise be required, for example, for beam expansion. This saves installation space in the 3D printing device.

[0016] The invention also includes embodiments which provide additional advantages.

[0017] One embodiment provides that the input coupling deflection structure and the output coupling deflection structure are designed as a holographic element with at least one optical grating, in particular a holographic volume grating or a holographic surface grating.

[0018] A holographic element, also known as a holographic optical element (HOE), is an optical element whose operating principle is based on holography and can be manufactured using holographic processes, i.e., holographic exposure. For this purpose, an interference pattern created by the superposition of two coherent waves of the same wavelength can be recorded on a light-sensitive layer. In this way, holographic elements such as gratings, lenses, mirrors, and beam splitters can be manufactured that have similar properties to conventional optical components. A holographic element can, in particular, be designed as an optical grating or diffraction grating.

[0019] Optical gratings, also called diffraction gratings, as well as their mode of operation and manufacturing processes are generally known. In principle, optical gratings can be formed as at least partially periodic structures, so-called grating structures, in a substrate which can bring about light guidance through the physical effect of diffraction, as is known, for example, from mirrors, lenses or prisms. When light, i.e. light rays, fall on the optical grating, whereby the incident light rays in particular satisfy the Bragg equation, the light rays are diffracted or deflected by the optical grating. The light guidance can thus occur in particular through interference phenomena of the light rays diffracted by the optical grating. The deflection structure can accordingly also be referred to as a diffraction structure.A holographic surface grating and a holographic volume grating are holographic optical elements that can be manufactured in particular by a holography process.

[0020] An optical grating can preferably be designed to be angle- or direction-selective and / or wavelength- or frequency-selective with respect to the incident light. Thus, only light incident on an optical grating from a predetermined direction of incidence, for example at a predetermined angle, can be deflected. Light incident on the optical grating from a different direction is preferably not deflected, or the greater the difference from the predetermined direction of incidence, the less deflected it is. Additionally or alternatively, only light of one wavelength, or light that deviates from the predetermined wavelength by at most a predetermined wavelength range, can be deflected by the optical grating at a specific diffraction angle.In other words, for example, an optimal wavelength can be specified at which only a portion of the light in a certain wavelength or frequency range around the optimal wavelength is deflected by the optical grating (e.g. a central optimal wavelength and a range with wavelength values ​​up to + / - 10 percent of the optimal wavelength), while the remaining portion of the light can propagate through the grating without being deflected. At least a monochromatic light portion can thus be split off from polychromatic light that hits the optical grating. The deflection effect is thus frequency-selective and / or angle-selective, with the deflection effect being maximum for an optimal wavelength and decreasing or becoming weaker towards longer and shorter wavelengths, for example according to a Gaussian bell.In particular, the deflection effect only affects a fraction of the visible light spectrum and / or in an angular range of less than 90 degrees.

[0021] Optical gratings can particularly preferably be produced by exposing a substrate, for example, photolithographically or holographically. In this context, the optical gratings can then also be referred to as holographic or holographic-optical gratings. Two types of holographic-optical gratings are known: holographic surface gratings (SHGs for short) and holographic volume gratings (VHGs for short). With holographic surface gratings, the grating structure can be created by optically deforming a surface structure of the substrate. The changed surface structure can deflect incident light, for example, by reflecting it. Examples of holographic surface gratings are so-called sawtooth or blaze gratings.In contrast, in holographic volume gratings, the grating structure can be incorporated into the entire volume or a portion of the volume of the substrate. Holographic surface gratings and holographic volume gratings are generally frequency-selective.

[0022] Glass, preferably quartz glass, is particularly suitable as a substrate material for incorporating an optical grating. Alternatively or additionally, a polymer, in particular a photopolymer, or a film, in particular a photosensitive film, for example made of plastic or an organic material, can also be used. When using such substrates, it should also be noted that the material, especially in substrate form, has flexible and optical waveguide properties. Substrates that have a deflection structure for diffracting light, for example in the form of an optical grating, can also be referred to as holographic optical elements (HOEs).

[0023] A further embodiment provides that the illumination device further comprises an infrared radiator, and wherein the input-coupling deflection structure and the output-coupling deflection structure are designed as a multiplex diffraction structure designed to diffract light of at least the predetermined wavelength and light from the infrared radiator at a predetermined angle. In other words, in addition to a light source that emits light with the predetermined wavelength for photopolymerization of the synthetic resin, the illumination device can comprise an infrared radiator that can, for example, heat the synthetic resin and thus liquefy the regions of the synthetic resin that do not correspond to the exposure pattern with the first predetermined wavelength. For this purpose, the input-coupling deflection structure and the output-coupling deflection structure can preferably be designed as a multiplex diffraction structure.

[0024] A diffraction structure, such as an optical grating, is usually frequency-selective. However, optical gratings capable of diffracting polychromatic light are also known. These are called multiplexed volume holographic gratings (MVHGs) and can be manufactured, for example, by changing the periodicity of the grating structure of an optical grating or by arranging several holographic volume gratings in series, creating a multiplexed diffraction structure.

[0025] This embodiment provides the advantage that a temperature of the resin bath can be maintained to maintain the viscosity of the resin without using space-consuming heating devices.

[0026] A further embodiment provides that the coupling-in region and the coupling-out region are formed integrally with the carrier medium or wherein the carrier medium is formed as a separate element from the coupling-in region and the coupling-out region. In the first case, the coupling-in region and the coupling-out region can thus, for example, be incorporated directly into a surface structure of the carrier medium. The carrier medium itself can thus be formed as an HOE, for example, etched or lasered. In the second case, the carrier medium can be formed separately from the coupling-in region and the coupling-out region. The coupling-in region and the coupling-out region can each form an element, for example, and the carrier medium can form another element which rests against the respective elements. The coupling-in region and the coupling-out region can thus be formed in at least one HOE.This allows for a wider range of carrier medium options. For example, the coupling-in and coupling-out regions can be formed in different sections of a holographic foil or plate. To attach the foil or plate to the carrier medium, the foil or plate can be glued to the carrier medium. Alternatively, the holographic foil can also be designed as an adhesive foil and adhere directly to the surface of the carrier medium through molecular forces, i.e., without adhesive.

[0027] A further embodiment provides that the coupling-in region has a smaller dimension than the coupling-out region, wherein the coupling-in deflection structure has a diffusion grating structure designed to deflect light rays of the light incident on the coupling-in deflection structure to varying degrees depending on the point of incidence, so that the coupling-in deflection structure fans out the light rays onto the coupling-out deflection structure, and wherein the coupling-out deflection structure has a bundling grating structure designed to deflect light rays of the light to varying degrees depending on the point of incidence and to parallelize or focus them for coupling out of the carrier medium onto the photosensitive synthetic resin of the synthetic resin bath. In other words, light incident on the coupling-in deflection structure can be expanded to a dimension of the coupling-out region.

[0028] A diffraction grating structure can have an inhomogeneous diffraction structure that can, for example, diffract light rays from an edge of the diffraction structure more strongly than light rays from a center of the diffraction structure, allowing the light rays to be fanned out. Accordingly, a focusing grating structure can have a grating structure in which light rays can be focused depending on their incident position. Preferably, in this embodiment, the focusing grating structure and the diffraction grating structure, and the corresponding spacing between the two structures, are selected such that the light rays diverge from the diffraction grating structure to the focusing grating structure and are parallelized again by the focusing grating structure.This arrangement is comparable to a Galilean telescope, in which a converging lens and a diverging lens are arranged one behind the other such that the focal lengths of the two lenses converge at a point behind the diverging lens. This design offers the advantage of allowing light to be distributed over a large area without requiring additional space for fanning out the light beams. Furthermore, a fanned-out light beam can be directed back onto the resin bath in a parallel direction, which can increase the precision of a 3D print.

[0029] A further embodiment provides that the illumination device comprises a projector with a replaceable photomask, which is designed to define an emission characteristic forming the exposure pattern for exposing the synthetic resin. The replaceable photomask of the projector can serve as a negative image that can generate the exposure pattern for irradiating the synthetic resin, wherein the replaceable photomask can preferably be exchanged by means of an exchange device, corresponding to a desired exposure pattern, for example, similar to a slide projector. Furthermore, the projector can be designed to change the intensity of the projector image over a large area or in a partial area of ​​the projector image by varying the exposure time.This design offers the advantage that the replaceable photomask can be used to define a variable radiation characteristic, allowing areas to be exposed for longer or more intensely.

[0030] A further embodiment provides that the illumination device has a focusing device designed to emit focused light beams, i.e. converging light beams, onto the coupling-in region, wherein the focused light beams, after transmission through the carrier medium to the coupling-out region and after exiting the coupling-out region, intersect in a focal plane in the synthetic resin bath. In other words, the illumination device can comprise a focusing device, in particular a lens or a lens system that can focus light beams. The focusing device can focus the light beams in such a way that a focal point, i.e. the point at which the light beams intersect, or a focal plane lies in the synthetic resin bath. Preferably, an intensity of the light beams can be selected in such a way that curing of the synthetic resin in the synthetic resin bath only occurs in the focal plane.This design offers the advantage that a larger gap can be created between the bottom of the resin bath and the lifting device, which can then be cured, i.e., photopolymerized, by adjusting the focal plane, for example, from top to bottom, i.e., from the lifting device to the bottom of the resin bath. However, it is also possible to cure two or more focal planes simultaneously by appropriately adjusting the focus device, thus enabling faster 3D printing.

[0031] A further embodiment provides that the illumination device has a scanning device with a light source that is designed to polymerize the photosensitive synthetic resin according to a scanning position of the scanning device by scanning the coupling region. The scanning device can, for example, have a movable illumination bar or a laser with a deflection mirror, wherein the scanning device can emit the light according to a desired exposure pattern into the coupling region, from where it can then be transmitted through the carrier medium to the corresponding location in the synthetic resin bath for curing the synthetic resin. In this embodiment, too, a variable exposure time can be provided for a desired radiation characteristic. This embodiment offers the advantage that a desired exposure pattern can be quickly changed for each layer of the 3D print.

[0032] One embodiment provides that a camera device is further provided, which is arranged next to the illumination device and is designed to record at least one image of a polymerization state of the synthetic resin for monitoring the photopolymerization. The camera device records the image of the polymerization state of the synthetic resin, which falls from the synthetic resin bath back via the decoupling region, the carrier medium, and the coupling region into the camera device. In other words, light from the synthetic resin bath can be redirected via the same path along which the light with the predetermined wavelength is guided from the illumination device into the synthetic resin bath, i.e., the coupling region, the carrier medium, and the decoupling region. A camera device can be provided next to the illumination device to record this light for recording an image.In particular, a polymerization state—that is, the current curing of the synthetic resin—can be recorded, allowing monitoring of the curing, i.e., photopolymerization. This embodiment offers the advantage of allowing monitoring of the 3D printing process, allowing any errors to be corrected or avoided. This can improve the quality of the 3D print.

[0033] Another embodiment provides for the carrier medium to form a base of the resin bath. In other words, the base, in particular the transparent base of the resin bath, can be formed from the carrier medium, with the coupling-out region preferably occupying a large portion of the base of the resin bath. This saves space because it enables a large-area distribution of the light via the carrier medium and thus the resin bath.

[0034] The invention also includes combinations of the features of the described embodiments.

[0035] Exemplary embodiments of the invention are described below. Shown are: Fig. 1 is a schematic cross-sectional view of an exemplary embodiment; Fig. 2 is a schematic representation of an exemplary embodiment; Fig. 3 a schematic representation of another exemplary embodiment; Fig. 4 a schematic representation of another exemplary embodiment.

[0036] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that can be considered independently of one another, each of which also develops the invention independently of one another. Therefore, the disclosure is intended to encompass combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0037] In the figures, the same reference symbols designate elements with the same function.

[0038] In Fig. Figure 1 shows a schematic cross-sectional view of a 3D printing device 10 according to an exemplary embodiment. The 3D printing device 10 has a resin bath 12 in which photosensitive resin 14 can be located. The resin 14 can polymerize, i.e., harden, using light, in particular light of a predetermined wavelength, such as UV light, to form a hardened body 16, which can be an object 16 to be printed, in particular a resin structure.

[0039] Furthermore, the 3D printing device 10 may have an illumination device 18, which may be configured to emit light with the predetermined wavelength.

[0040] A carrier medium 20 can be arranged beneath the synthetic resin bath 12, which can have an input coupling region 22 and an output coupling region 24. The carrier medium 20 can be formed, for example, using a layered construction, wherein two light-conducting elements 26, such as glass or plastic plates, can form the cover layers 26 for a holographic-optical element 28, or holographic element 28 for short. Alternatively or additionally, the holographic element 28 can also be created by stacking several holographic elements.

[0041] The holographic element 28 can, for example, be a photopolymer film or a glass that is inserted, preferably glued, between the two cover layers 26. Furthermore, the holographic element 28 can be formed by holographic exposure methods in such a way that deflection structures are formed, such as a holographic volume grating or a holographic surface grating.

[0042] In the coupling region 22, a coupling deflection structure 30 can thus be created, which is designed to couple light with the specified wavelength from the illumination device 18 into the carrier medium 20 in the direction of the coupling-out region 24. "Toward the coupling-out region" here means a macroscopic direction from the measuring region along the carrier medium to the coupling-out region 24, or a directional vector in the direction of propagation of the light by means of internal reflection. Transmission by means of internal reflection means that the coupled-in light rays satisfy a critical angle condition for total internal reflection. A light path can, of course, have a zigzag course due to the internal reflection.

[0043] Furthermore, the input-coupling deflection structure 30 can have a diffraction grating structure that deflects the light rays incident on the input-coupling deflection structure 30 to varying degrees depending on the point of incidence, so that the light rays are fanned out onto an output-coupling deflection structure 32 in the output-coupling region. The output-coupling deflection structure 32 can be formed from the same holographic-optical element 28 by exposing the holographic-optical element 28 in the output-coupling region 24 using holographic exposure methods in such a way that an optical grating, in particular a holographic volume grating or a holographic surface grating, is formed. The output-coupling deflection structure 32 is designed to couple the light coupled into the carrier medium 20, which falls on the output-coupling deflection structure 32, out of the carrier medium 20 into the synthetic resin bath 12 for photopolymerization of the synthetic resin.In particular, the output deflection structure 32 can have a bundling grating structure that deflects light rays to varying degrees depending on the incident location and thus re-parallelizes or focuses the light rays fanned out by the input deflection structure 30. Thus, the input deflection structure 30 and the output deflection structure 32 can be used as a beam expander.

[0044] Thus, light with the predetermined wavelength, which is emitted by the illumination device 18 onto the coupling region 22, can be coupled into the carrier medium 20 by the coupling deflection structure 30 and forwarded by means of internal reflection to the coupling-out region 24, where it can then be emitted by the coupling-out deflection structure 32 into the synthetic resin bath 12 in an area that is enlarged compared to the coupling region 22, where it can cure a layer of the synthetic resin 14.

[0045] The synthetic resin 14 can cure, in particular, on the underside of a lifting device 34, wherein the lifting device 34 can pull the resulting object 16 layer by layer out of the synthetic resin bath 12, allowing the synthetic resin 14 to flow into a gap between a bottom of the synthetic resin bath and the object 16, where the subsequently flowed synthetic resin 14 can then be exposed to light again. Thus, the object 16 can be formed step by step or continuously.

[0046] The illumination device 18 can comprise a light source 36, which can be, for example, a projector with a replaceable photomask. The photomask can, in particular, define an emission characteristic forming the exposure pattern for exposing the synthetic resin. Furthermore, the illumination device 18 can have an infrared radiator 38. The infrared radiator 38 can, for example, be designed to emit infrared light onto the coupling deflection structure 30. The coupling deflection structure 30 can, in particular, also be designed as a multiplex diffraction structure, which means that, in addition to the light with the predetermined wavelength, it can also couple light from the infrared radiator 38 into the carrier medium 20.Likewise, the output deflection structure 32 can be designed as a multiplex diffraction structure that can diffract at least the light of the predetermined wavelength and the light of the infrared radiator at a predetermined angle, so that the light of the two wavelengths can be radiated onto the synthetic resin 14.

[0047] In addition to the illumination device 18, a camera device 40 can be provided, which is designed to record at least one image of a polymerization state of the synthetic resin in order to monitor a 3D printing production process. For this purpose, the camera device 40 can, for example, detect light that is reflected by the object 16 and transmitted back via the coupling-out region, the carrier medium, and the coupling-in region. Thus, an image of the current polymerization state of the synthetic resin can be recorded and, for example, possible errors can be detected and corrected by controlling the illumination device 18 to change the exposure pattern. For this purpose, the recorded layer image can be analyzed and compared with a digital layer image.If deviations such as distortion or holes are detected, these can be compensated for by corrective measures such as changing the exposure time, the exposure intensity and / or a modification of the exposure pattern.

[0048] In Fig. 2 shows a schematic representation of an exemplary embodiment. This representation shows a plan view of a carrier medium 20 with an input coupling region 22 and an output coupling region 24. In this embodiment, the illumination device 18 can, for example, have a scanning device 42 with the light source 36. In this embodiment, the scanning device 42 can, for example, be a guide rail system that can move the light source 36, which in this embodiment is designed as an exposure bar 36, over the input coupling region 22 and, depending on the position, can provide a suitable exposure for generating the exposure pattern. For this purpose, for example, a variable exposure time can also be implemented for a respective position of the exposure bar 36.

[0049] By fanning out the light from the coupling-in region 22 to the coupling-out region 24, it can also be achieved that by scanning the comparatively small coupling-in region 22, the comparatively large coupling-out region 24 is scanned, which is indicated by the arrows to the right.

[0050] In Fig. Figure 3 shows a schematic representation of another exemplary embodiment. This representation again shows the carrier medium 20 with the coupling-in region 22 and the coupling-out region 24. In this embodiment, the illumination device 18 can have a deflection mirror as a scanning device 42, which can preferably be tilted by means of a piezoelectric element and can thus deflect a light beam originating from the light source 36, which can in particular be a laser. Light beams from the light source 36 can thus be coupled into the carrier medium via the deflection mirror 42 at a point in the coupling-in region 22 and coupled out at a corresponding point in the coupling-out region 24.In particular, a focusing device 44 can also be provided which can focus light rays of the light source 36 in the direction of the coupling-in region, wherein the focused light rays, after transmission through the carrier medium to the coupling-out region 24 and after exiting the coupling-out region, intersect in a focal plane behind the coupling-out region 24, wherein the focal plane can preferably be within the synthetic resin bath 12, whereby, for example, different or multiple layers can be exposed simultaneously.

[0051] In Fig.Figure 4 shows a schematic representation of another exemplary embodiment. In this embodiment, the carrier medium 20 in the coupling region 22 can have a photodiode matrix 46 superimposed thereon, which can comprise, for example, an LED or OLED matrix. This allows, for example, an exposure pattern to be emitted from the photodiode matrix 46 directly into the coupling region 22. Subsequently, after being transmitted through the carrier medium 20, the exposure pattern can be guided over a large area via the coupling-out region 24 into the synthetic resin bath to expose the synthetic resin 14 there.

[0052] Overall, the examples show how the invention can provide 3D printing via a holographic optical element.

Claims

[1] 3D printing device (10) for photopolymerizing a photosensitive resin (14) by an exposure pattern, comprising - a resin bath (12) for the photosensitive resin (14) with a lifting device (34), wherein the photosensitive resin (14) is polymerizable as a cured body on the lifting device (34) by means of light of a predetermined wavelength, and wherein the lifting device (34) is designed to move the cured body up and out of the resin bath (12) in order to change an exposure plane for the photosensitive resin with respect to the body; - a carrier medium (20) which is designed to transmit coupled-in light as a light guide by means of internal reflection, and having a coupling-in region (22) and a coupling-out region (24) which are arranged in different sections of the carrier medium; - an illumination device (18) which is designed to radiate the light onto the coupling region (22); wherein - the coupling-in region (22) has a coupling-in deflection structure (30) which is designed to couple light with the predetermined wavelength, which falls from the illumination device (18) onto the coupling-in deflection structure (30), into the carrier medium (20) in the direction of the coupling-out region (24); wherein - the coupling-out region (24) is arranged below the synthetic resin bath (12) and has a coupling-out deflection structure (32) which is designed and arranged to couple the coupled-in light with the predetermined wavelength, which falls on the coupling-out deflection structure (32), as an exposure pattern from the carrier medium (20) onto the photosensitive synthetic resin (14) of the synthetic resin bath for photopolymerization of the synthetic resin - wherein the input coupling deflection structure (30) and the output coupling deflection structure (32) are designed as an interference structure, grating structure, lens system or mirror. [2] 3D printing device (10) according to one of the preceding claims, wherein the coupling-in region (22) and the coupling-out region (24) are formed integrally with the carrier medium (20) or wherein the carrier medium (20) is formed as a separate element from the coupling-in region (22) and the coupling-out region (24). [3] 3D printing device (10) according to one of the preceding claims, wherein the input coupling region (22) has a smaller dimension than the output coupling region (24), wherein the input coupling deflection structure (30) has a diffusion grating structure which is designed to deflect light rays of the light incident on the input coupling deflection structure (30) to different degrees depending on an incidence location, so that the input coupling deflection structure (30) fans out the light rays onto the output coupling deflection structure (32), and wherein the output coupling deflection structure (32) has a bundling grating structure which is designed to deflect light rays of the light to different degrees depending on the incidence location and to parallelise or focus them for coupling out of the carrier medium onto the photosensitive synthetic resin (14) of the synthetic resin bath. [4] 3D printing device (10) according to one of the preceding claims, wherein the illumination device (18) comprises a projector with a replaceable photomask, which is designed to define a radiation characteristic forming the exposure pattern for exposing the synthetic resin. [5] 3D printing device (10) according to one of the preceding claims, wherein the illumination device (18) has a focus device (44) which is designed to emit focused light beams onto the coupling-in region (22), wherein the focused light beams, after transmission through the carrier medium (20) to the coupling-out region (24) and after exiting the coupling-out region (24), intersect in a focal plane in the synthetic resin bath (12). [6] 3D printing device (10) according to one of the preceding claims, wherein the illumination device (18) comprises a scanning device (42) with a light source (36) which is designed to polymerise the photosensitive synthetic resin (14) in accordance with a scanning position of the scanning device by scanning the coupling region. [7] 3D printing device (10) according to one of the preceding claims, wherein a camera device (40) is further provided, which is arranged next to the illumination device (18) and is designed to record at least one image of a polymerization state of the synthetic resin for monitoring the photopolymerization, in that the camera device (40) records the light of the image of the polymerization state of the synthetic resin, which falls from the synthetic resin bath (12) back via the decoupling region (24), the carrier medium (20) and the coupling region (22) into the camera device (40). [8] 3D printing device (10) according to one of the preceding claims, wherein the carrier medium (20) forms a bottom of the resin bath.

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