Method for producing optical element by processing optically reactive material and optical element

Abstract

An optical element produced by processing an optically reactive material. According to the invention, a starting material (3) is provided, which has optical reactivity and fills the working volume (2); the starting material is processed in a working volume by irradiating light having a first wavelength and light having a second wavelength different from the first wavelength, and at least one material property of the starting material is changed by optical treatment.

Description

Technical Field

[0001] The invention relates to a method for producing an optical element by processing an optically reactive material, as well as to an optical element produced by this method, a corresponding device and an optical element produced according to this method. Background Art

[0002] Subtractive methods for producing optical components, such as milling, grinding and polishing workpieces, are time-consuming and expensive. Other forming methods, such as precision blank pressing of glass or injection molding of polymer materials, increase manufacturing tolerances and initial costs for mold production. In contrast, additive manufacturing processes offer the advantage of saving materials, time and cost when producing any three-dimensional object.

[0003] Optical components can be manufactured additively by various methods, such as stereolithography or digital light processing. However, both methods can only be manufactured in layers for process reasons. In addition, only low-viscosity materials can be used, as they have good flow properties. Curved surfaces always suffer from a loss of geometric accuracy in the case of layer thicknesses between 10 μm and 100 μm. In addition, layered manufacturing leads to inhomogeneous densities and thus to inhomogeneous optical and mechanical properties within the component. In addition, layered manufacturing with these methods is always associated with long waiting times for the individual process steps, resulting in long process times. Finally, in the case of the above-mentioned methods, the suspended structural parts must have support structures. Not only is the manufacture of these support structures time-consuming and material-intensive, which increases costs, but the contact points between these support structures and the component further reduce the surface quality of the components produced in this way. Although the surface quality can be further improved by post-processing steps such as polishing or coating, this also leads to a loss of geometric accuracy and is both time-consuming and expensive as a further processing step.

[0004] In "Continuous Liquid Interphase Production" (CLIP, Nature Materials, Vol. 5, pp. 365-369 (2006)), the installation volume is irradiated from the bottom up through an oxygen-permeable membrane to form a chemical inhibition zone, so that isotropic objects can be produced continuously. Although this method is much faster than traditional stereolithography, it still relies on the fluidity of the photosensitive resin and therefore cannot use high-viscosity materials, which are very suitable for producing polymers with high mechanical strength. In addition, this method cannot omit the support structure, which has the disadvantages mentioned above. In addition, since cationic polymer resins or thiol-ene resins do not have oxygen inhibition functions, there are also limitations on the chemical properties of the resin. Finally, additives such as alkalis cannot be used because these additives counteract the inhibitory effect of oxygen.

[0005] Document WO 2014 / 108364 A1 discloses a multi-jet method in which a layer of small droplets of photosensitive resin is deposited on a surface in a precisely positioned manner and subsequently cured by UV irradiation. Due to the careful control of the wetting properties, the natural curvature of the individual top surfaces can be exploited, resulting in extremely high surface quality, although the manufacturing of this patent is also layered. However, due to process reasons, low-viscosity materials must also be used in this case, and this method still only allows the free formation of optical surfaces and is further limited by the printable angles and other geometries.

[0006] Document DE102020108375B3 discloses a method for producing an intraocular lens, the steps of which are as follows: providing a container which is transparent to electromagnetic radiation and in which a liquid which can be cured using electromagnetic radiation is placed; irradiating the liquid with a set of images formed by electromagnetic radiation, each image showing an intraocular lens, wherein each image in the set of images irradiates into the liquid at a different irradiation angle relative to a reference plane extending through the liquid, as a result of which the liquid is cured, and the cured liquid forms an intraocular lens. A limitation of this method is that highly anisotropic structures or sharp edges cannot be formed, and therefore the structural freedom is limited.

[0007] In the production of optical components, the starting material can be optically treated by irradiating it with light of one or more wavelengths, thereby changing at least one material property of the starting material. Such curing of the starting material by optical treatment is thus known per se.

[0008] Document US Pat. No. 4,041,476 describes a method and a device by means of which a three-dimensional body can be produced from a starting material, during which light beams of different wavelengths are irradiated onto the starting material and overlap at certain points.

[0009] Polymerization is a reaction used to produce plastic materials. Polymerization is a form of optical processing of the starting material, the reaction being initiated by irradiating light onto the polymerizable starting material. Such polymerizable starting substances or materials are also called photopolymers. These polymers change their material properties when irradiated with light. Irradiation with light brings about structural changes, such as photochemical curing of the material by crosslinking. Photopolymerization is used, for example, in 3D printing to produce three-dimensional objects from the polymerizable starting material.

[0010] The starting material itself can be transparent and therefore insensitive to the irradiated light. Photoinitiator molecules are mixed into it, absorb light and initiate the curing of the starting material. To process the starting material in a constant (free) volume, freely selected points must be located in the three-dimensional volume. One approach is to use special photoinitiators, also called dual-color photoinitiators (WO2020 / 245456A1 and WO2021 / 089090A1). Such dual-color photoinitiators are preferably or entirely excited by absorbing photons of two different wavelengths or two different non-overlapping wavelength ranges. Dual-color photoinitiators can be produced in different ways. In one variant, the molecule is in a basic / normal state (A) in the absence of light irradiation. In this state, the molecule is in a wavelength There is an absorption band at one wavelength and at another There is minimal absorption.

[0011] The molecule then enters a pre-activated or excited intermediate state (B). The pre-activated or excited intermediate state is formed by the absorption of the basic state A at a wavelength of In the intermediate state B, the photoinitiator molecule has a wavelength of Absorption band. Wavelength The absorption band disappears. Alternatively, keep the wavelength This can create an undesirable, competing transition channel to state C. In the absence of light, the photoinitiator molecule returns to state A. Alternatively, the photoinitiator molecule After light excitation, it returns to state A. This allows targeted inhibition of the initiator in state B.

[0012] The excited state C of the molecule is formed by B absorbing the wavelength State C stimulates chemical and / or physical changes in the molecule's surroundings. There is no reverse reaction to B, but it is possible. Summary of the invention

[0013] The problem underlying the present invention is to determine a method for producing optical elements by processing optically reactive materials, by which method the starting material can be effectively subjected to multi-dimensional optical processing.

[0014] As a solution, a method for producing an optical element by processing an optically reactive material is provided, as well as an optical element according to the independent claims. The dependent claims relate to embodiments.

[0015] According to one aspect, a method for producing an optical element by treating an optically reactive material is provided, the method comprising the following steps: providing a starting material, the starting material being optically reactive and filling a working volume; optically treating the starting material in the working volume by irradiating light of a first wavelength and light of a second wavelength different from the first wavelength, wherein at least one material property of the starting material is changed by the optical treatment. The optical treatment comprises the following steps: irradiating a first layer of a partial volume of the working volume filled with the starting material with light of the first wavelength; irradiating a first layer of a partial volume of the working volume with light of the second wavelength, wherein the light of the second wavelength is projected into the working volume in this case; irradiating a second layer of a partial volume of the working volume filled with the starting material with light of the first wavelength, the second layer of the partial volume being different from the first layer of the partial volume; irradiating a second layer of a partial volume of the working volume with light of the second wavelength, wherein the light of the second wavelength is projected into the working volume in this case; repeating the previous steps, optically treating the starting material in the working volume in layers, until the volume of the starting material to be treated has been optically treated, the volume of the starting material to be treated is completely or partially surrounded by the working volume, in the process, a green body is formed from the starting material; further treating the green body, so that the optical element is at least partially formed by the green body, in particular completely formed by the green body.

[0016] The method comprises in particular the following steps: providing a starting material, which is optically reactive and fills a working volume; optically treating the starting material in the working volume by irradiating it with light of a first wavelength and light of a second wavelength different from the first wavelength, wherein the light of the first wavelength and the light of the second wavelength are provided by an illumination device, and wherein at least one material property of the starting material is changed by the optical treatment. The optical processing comprises the following steps: irradiating a first layer of a local volume of a working volume filled with a starting material with light of a first wavelength; irradiating a first layer of a local volume of the working volume with light of a second wavelength, wherein the light of the second wavelength is in this case projected entirely or only partially onto the first layer of a local volume in the working volume by a projection device; irradiating a second layer of a local volume of the working volume filled with a starting material including the starting material with light of the first wavelength, the second layer of a local volume being different from the first layer of a local volume; irradiating a second layer of a local volume of the working volume with light of a second wavelength, wherein the light of the second wavelength is in this case projected entirely or partially onto only the second layer of a local volume in the working volume by a projection device; repeating the preceding steps to perform layered optical processing on the starting material in the working volume until the volume of the starting material to be processed has been optically processed and the volume of the starting material to be processed is entirely or partially surrounded by the working volume, during which a green body (green body) is formed from the starting material; further processing the green body so that the optical element is at least partially formed by the green body, in particular entirely formed by the green body.

[0017] Another aspect is to provide an optical element produced by the above method.

[0018] This method allows the efficient production of optical elements. In this case, the starting material has already entered and filled the working volume before the irradiation with light of the first wavelength and the second wavelength, and the starting material can be optically processed in a multidimensional or volumetric manner in the working volume, so that at least one material property of the starting material is changed by irradiation with light of the first wavelength and the second wavelength, and optionally by irradiation with light of one or more other wavelengths, and the optical element is obtained by further processing (post-processing). By this method, a volume 3D printing process can be provided, which volume 3D printing process can be operated in particular continuously, so that isotropic objects can be produced.

[0019] In this context, the present invention is based on the surprising discovery that a volumetric 3D printing method, comprising irradiating a local volume of a corresponding layer with light of a first wavelength and a second wavelength, is very suitable for the production of optical elements. In particular, optical elements with excellent properties and high quality can be efficiently produced using a corresponding volumetric 3D printing method, comprising irradiating a local volume of a corresponding layer with light of a first wavelength and a second wavelength. The present invention thus breaks the hitherto prevailing view that optical elements, in particular large optical elements, cannot be produced using volumetric 3D printing methods and cannot obtain the desired properties; in particular, according to studies, the present invention has been able to demonstrate that axial lithography methods such as CT-based (Computational Axial Lithography, CAL-method) are not suitable for the production of optical elements, in particular because such methods are only suitable to a limited extent for the production of micro-optical elements or lead to artifacts on the surface of the element, making it impossible to use the printed element as an optical element. In other words, the inventors have been able to find that it is still possible to produce optical elements using certain volumetric 3D printing methods, in particular optical elements produced using volumetric 3D printing methods comprising irradiating a local volume of a corresponding layer with light of two different wavelengths, in particular optical elements produced from polymeric or plastic materials.

[0020] In addition, a device for processing optically reactive materials is disclosed, which may include the following components: a working volume configured to receive an optically reactive starting material, which partially or completely fills the working volume; an illumination device configured to provide light of a first wavelength and light of a second wavelength for irradiating the working volume containing the starting material. The illumination device may be configured to optically process the starting material in the working volume as follows: irradiate a first layer of a local volume in the working volume partially or completely filled with the starting material with light of the first wavelength; irradiate the first layer of a local volume in the working volume with light of the second wavelength, irradiate a second layer of a local volume in the working volume with light of the first wavelength, the second layer of the local volume being different from the first layer of the local volume; irradiate the second layer of the local volume in the working volume with light of the second wavelength; repeat the previous steps to optically process the starting material in the working volume in layers until the volume of the starting material has been optically processed and the volume of the starting material is completely or partially surrounded by the working volume, thereby in particular forming a corresponding green body.

[0021] The device may include, in particular, the following components: a working volume configured to receive a starting material, which is optically reactive and fills the working volume; an illumination device configured to irradiate light of a first wavelength and light of a second wavelength onto the working volume containing the starting material; and a projection device configured to project the light of the second wavelength onto the working volume filled with the starting material by irradiation, into a layer local volume of the working volume, and only fully or partially irradiate the layer local volume. The illumination device and the projection device can also be further configured to perform the following optical treatment on the starting material in the working volume: irradiate a first layer of the local volume of the working volume filled with the starting material with light of a first wavelength; irradiate the first layer of the local volume of the working volume with light of a second wavelength, wherein the light of the second wavelength is in this case projected by the projection device into the working volume in a manner that the first layer of the local volume is fully or partially irradiated only; irradiate a second layer of the local volume of the working volume filled with the starting material including the starting material with light of the first wavelength, the second layer of the local volume being different from the first layer of the local volume; irradiate a second layer of the local volume of the working volume with light of a second wavelength, wherein the light of the second wavelength is in this case projected by the projection device into the working volume in a manner that the second layer of the local volume is fully or partially irradiated only; repeat the above steps to perform layered optical treatment on the starting material in the working volume until the volume of the starting material to be treated is optically treated, and the volume of the starting material to be treated is fully or partially optically treated and surrounded by the working volume, in the process, a green body is formed from the starting material. By further treatment, an optical element can be formed (at least partially, in particular completely) from the green body.

[0022] The lighting device (also referred to herein as illumination device) of the apparatus may be configured to create light segments in the working volume, and may also include a light segment creation device for creating light segments in the working volume.

[0023] The lighting device may include one of the following elements: a Powell lens, a cylindrical lens (especially a plano-convex cylindrical lens), a polygonal mirror or a galvanometer mirror. Alternatively or additionally, the lighting device may also include, for example: a laser, an LED or a thermal light source.

[0024] Alternatively or additionally, the illumination device may further comprise, for example: a mirror or a light deflecting device, which is configured to reflect light emitted from the working volume back to the opposite direction of the working volume by reflection.

[0025] The illumination device may be configured to allow layers that are further away from the light source of the second wavelength of light to be processed earlier in the course of time.

[0026] The layer partial volumes of the working volume are irradiated successively with a first wavelength and a second wavelength, so that a photo-induced reaction is induced in the starting material. The layer partial volumes that are successively photo-treated contain partial volumes of the starting material that were introduced and filled into the working volume before the manufacturing process (photo-treatment) started. In contrast to known methods, in the case of the photo-treatment, the starting material need not be applied in layers, but rather a subsequent layer-wise photo-treatment (of the layers just applied) is performed respectively after the layer application.

[0027] In the working volume previously filled with the starting material, the projection of light of the second wavelength or the irradiation of light of the second wavelength will be accurately projected by means of the projection device into the layer partial volume currently being irradiated with the first wavelength, depending on the difference in the layer partial volume irradiated with the first wavelength. The projection device images the light of the second wavelength into the currently required layer partial volume. In this case, the projection device can image the light of the second wavelength into an image of at least two-dimensional shape in a projection plane or projection volume, which is located in the layer partial volume irradiated with the first wavelength of light. For example, a three-dimensional body can be produced layer by layer in the starting material in this way.

[0028] The further processing of the green body may in particular comprise at least one of the following steps: removing the green body from the starting material; treating (in particular washing) the green body with a solvent and / or (treatment) monomer; and drying the (washed) green body. The green body may be formed in an isotropic manner.

[0029] Alternatively, further processing steps can be carried out in the starting material (without removing the blank).

[0030] The solvent and / or (treatment) monomer may include a photoinitiator and / or a thermal initiator, which preferably reacts only at one wavelength (or a range of wavelengths). This allows for more efficient post-curing. In this case, the photoinitiator and / or the thermal initiator can be configured to be received on the surface of the green body. In particular, the photoinitiator and / or the thermal initiator can be dissolved in the solvent and / or the (treatment) monomer. For example, drying can be carried out by providing a gas flow (preferably a gas flow or a nitrogen flow) and / or providing heat (preferably at a temperature of at least 20°C). For example, Fouassier / Lalevée, Photoinitiators, Wiley-VCH (2021) describes photoinitiators.

[0031] Especially for high-viscosity starting materials, cleaning can be achieved by appropriate selection of solvent or (treatment) monomer, time, temperature and movement to make the green body surface smoother.

[0032] Additionally or alternatively, further processing of the green body may also include at least one of the following steps: photochemical post-curing of the green body, tempering of the green body (usually equivalent to thermal post-curing of the green body), grinding of the green body, polishing of the green body and coating of the green body (eg anti-reflective coating).

[0033] The green body may be coated using one or more chemical and / or physical coating methods, in particular to improve the surface properties of the green body and thus of the optical element. In particular, by applying at least one coating layer, the roughness, scratch resistance and / or reflective properties may be improved. Thus, in all embodiments, the applied coating may have a lower refractive index than the (actual) optical element (e.g. due to an anti-reflective coating), and / or the surface hardness of the optical element may be increased (e.g. by an anti-scratch layer).

[0034] The corresponding coating method may include spray coating, dipping, spin coating, sol-gel method or vapor deposition method, etc. After any coating is completed, further curing may be performed, such as photochemical curing or thermal curing.

[0035] The coating material applied by the corresponding coating method can be solid, paste, liquid or varnish, or gas. Therefore, the coating material can be applied to the green body in the form of powder, paste, liquid or varnish, gas or gas phase.

[0036] Coating can also be performed using the uncured starting material itself or another organic polymer or inorganic / organic hybrid material, which usually requires further curing, either photochemically or thermally.

[0037] Before applying the coating, the surface of the green body or the optical element can be chemically and / or physically treated, in particular activated, in order to achieve better adhesion of the coating. The corresponding treatment or activation can be carried out using plasma, in particular oxygen plasma. Alternatively or additionally, an adhesion promoter can also be used to achieve better adhesion of the coating to the green body or the optical element.

[0038] Photochemical post-curing can be carried out by means of isotropic irradiation (uniform irradiation from all directions). Tempering or thermal post-curing can be carried out by providing heat at a temperature of at least 50° C., in particular for a duration of at least 15 minutes, or by corresponding aging of the green body at a temperature of at least 50° C., in particular for a duration of at least 15 minutes.

[0039] By means of a control device connected to one or more light sources or irradiation devices (for providing light of a first wavelength and a second wavelength), and a projection device (the projection device is usually a component of the irradiation device), it can be determined whether a first layer partial volume or a second layer partial volume (of the starting material in the working volume) is irradiated, and based on this determination, the projection device is activated to project light of the second wavelength into the first and / or second layer partial volume. In this case, the control device provides data that define the current or current position of the layer partial volume irradiated by the light of the first wavelength. The projection device is thus controlled so that the projection generated by means of the projection device is formed in the projection plane or projection volume of the currently irradiated layer partial volume. In this way, the layer partial volumes of the starting material are processed successively layer by layer. In this case, the outer shape of the projection of the projection device may be different for different layer partial volumes, in particular depending on the three-dimensional volume produced in the starting material by means of the optical processing.

[0040] In one embodiment, the current or existing position of the layer partial volume illuminated by light of the first wavelength in the working volume can be detected by means of a measuring device, which then provides a measurement signal indicative of the position to the control device.

[0041] The light of the first wavelength and the light of the second wavelength are simultaneously and jointly irradiated into the first layer partial volume or the second layer partial volume at least in the time overlap period. In this embodiment, the layer partial volume and the area where the projection of the projection device is concentrated are simultaneously irradiated by the light of the first wavelength and the light of the second wavelength at least in the time overlap area.

[0042] The first layer partial volume and the second layer partial volume may form a contiguous layer partial volume of the starting material in the working volume.

[0043] The first layer partial volume and the second layer partial volume may be formed according to one of the following configurations of the partial volumes: overlapping at an edge, adjoining at an edge, and spaced apart from each other at an edge.

[0044] The light of the first wavelength may be irradiated along a first irradiation direction, and the light of the second wavelength may be irradiated onto the starting material in the working volume along a second irradiation direction extending perpendicular to the first irradiation direction. For example, in one embodiment, the first irradiation direction and the second irradiation direction may be at an angle of approximately 90°. Other angles of approximately 30° to 90° may also be provided between the optical axes of the irradiation directions.

[0045] The light of the first wavelength and / or the light of the second wavelength can be irradiated as pulsed light. The light pulses of the first wavelength and the second wavelength can be irradiated into the local volume of the layer currently being processed simultaneously or successively at a predetermined time interval. The light pulses of the two wavelengths can have the same or different temporal pulse widths. Alternatively, the light of the first wavelength or the light of the second wavelength can be irradiated as continuous light.

[0046] The starting material may be processed by an optical process in a manner corresponding to at least one of the following group of processing methods: curing, hardening, gelling and liquefying. In these or other embodiments, the starting material may be solid, liquid or paste.

[0047] In one embodiment, it may be provided that the starting material emits light due to optical treatment with light of the first wavelength and the second wavelength, in particular due to fluorescence or phosphorescence.

[0048] When illuminating the first layer partial volume and the second layer partial volume with light of the first wavelength, the layered illumination area of ​​the first light source (providing light of the first wavelength) can be moved relative to the working volume. In this embodiment, the layered illumination area for the light of the first wavelength is displaced relative to the starting material during the optical processing, so that the illumination area is extended or scanned over the working volume. The relative movement between the working volume and the illumination area can be achieved in a variety of ways. Displacement of the working volume and / or the first light source can be provided. Alternatively or additionally, the working volume and the first light source can be relatively fixed throughout the processing of the starting material. With the help of a light deflection device, the illumination area of ​​the light of the first wavelength emitted by the first light source is moved to the working volume containing the starting material.

[0049] The optical processing of the starting material can be observed with the aid of one or more light detectors, such as cameras and / or photodetectors. In this case, the process in the process (optical processing) can be studied, for example by measuring the transmitted light, whether the excitation light of the light segment and / or the light from the projection device. The light segment generator or the optional projection device can emit light of other wavelengths than the excitation wavelength, which are only used to observe changes in the material properties of the starting material (e.g. ongoing polymerization reactions).

[0050] By optical treatment, multicolor multiphoton polymerization ("xolography") can be induced in the starting material, resulting in a change in at least one material property of the starting material. For example, in one embodiment, the starting material can include a transparent organic polymer and / or an inorganic / organic polymer composite material, which is preferably cured by optical treatment. For example, in one embodiment, the starting material may include one or more of the following components: oligomers (e.g., acrylates, methacrylates, epoxies, vinyls, allyls, organopolysiloxanes, terminal functionalized polysiloxanes), functionalized and non-functionalized nanoparticles, monomers (e.g., acrylates, methacrylates, epoxies, vinyls, allyls), crosslinkers (e.g., multifunctional monomers, multifunctional thiols), dual-color photoinitiators, co-initiators, inhibitors, sensitizers, defoamers, post-treatment additives (e.g., additional photoinitiators and / or thermal initiators), solvents, additives, in particular additives for rheology control (rheology modifiers), in particular additives for rheology control for the starting material, additives for reducing surface tension, in particular additives for reducing surface tension for the starting material, additives for influencing optical properties, such as additives for adjusting or increasing transparency or adjusting the refractive index, in particular additives for influencing optical properties for the starting material or the optical element.

[0051] The two-color photoinitiator is capable of reacting to two different wavelengths of light, in particular causing local polymerization, thereby preferably producing selective curing. In one embodiment, a transparent container containing the monomer and the two-color photoinitiator can be illuminated from one side with a laser line, thereby generating light segments. A dynamic image can be projected onto the light segments. By moving the container, a cured object can be formed in a free-floating state.

[0052] The method can (preferably during dynamic image projection) include performing pixel shifting, preferably to achieve automatic smoothing of edges. In addition, the object can be split into individual layers with a layer thickness of ≤ 1 μm by software at a uniform printing speed, which preferably allows high resolution of the optical element.

[0053] The viscosity of the starting material can be 10 2 mPas to 10 7 mPas, preferably 3·10 3 mPas to 10 6 mPas, particularly preferably 10 3 mPas to 10 5 mPas, most preferably 10 4 mPas to 9.10 4 mPas.

[0054] The starting material may include a monomer mixture and / or an oligomer mixture, preferably with a corresponding viscosity. The monomer mixture and / or the oligomer mixture are preferably transparent. The monomer mixture and / or the oligomer mixture can stabilize the green body and / or the solidified object, and therefore especially does not need a supporting structure, to achieve complete structural freedom. The solidified object can be formed in a monomer mixture and / or an oligomer mixture in a free floating manner.

[0055] In particular, if the monomer mixture or oligomer mixture (generally the starting material) has a sufficiently high viscosity to support the solidified object, the solidified object (i.e., the green body) can be formed in a free-floating manner in the monomer mixture and / or oligomer mixture (generally the starting material). Alternatively or additionally, if the monomer mixture or oligomer mixture (generally the starting material) has non-Newtonian fluid flow characteristics, i.e., shear-thinning flow characteristics or shear-liquefying flow characteristics, and / or has a yield strength greater than the static shear load of the object, the solidified object can be formed in a free-floating manner in the monomer mixture and / or oligomer mixture (generally the starting material). The yield strength of the starting material can be determined, for example, by a rotational rheometer (plate-to-plate rheometer) under quasi-static loading of a "creep test" or a slow shear stress ramp.

[0056] The corresponding yield strength of the starting material is greater than the static shear load of the object, typically greater than or equal to 0.1 Pa, particularly 0.2 Pa, more particularly 0.3 Pa, more particularly 0.4 Pa, more particularly 0.5 Pa, more particularly 0.6 Pa, more particularly 0.75 Pa, more particularly 1 Pa. Therefore, the corresponding yield strength of the starting material is at least 0.1 Pa per cubic centimeter of working volume. Therefore, in a working volume of 1 cm 3 The yield strength of the starting material is at least 0.1 Pa. Therefore, in a working volume of 2 cm 3 When the yield strength of the starting material is at least 0.2Pa.

[0057] The static shear load of the object depends in particular on the geometry and size of the object and can be less than or greater than 0.5 Pa, depending on the geometry and size of the object. In order to give the monomer mixture or oligomer mixture (generally the starting material) corresponding rheological properties, it is advisable to stir the monomer mixture or oligomer mixture (generally the starting material) before the optical treatment, i.e. before printing. Thus, in particular after the starting material is charged into a container with a defined working volume, the starting material can be stirred for a certain time, in particular for at least one hour, in particular for at least six hours, more particularly for at least twelve hours, more particularly for at least eighteen hours, more particularly for at least twenty hours.

[0058] Alternatively or additionally, the corresponding yield strength of the starting material can also be set by admixing oligomers and polymers with non-Newtonian fluid properties and / or by admixing additives (rheology modifiers). Examples of oligomers with non-Newtonian fluid properties (non-exhaustive list): 1) linear polymers with medium and / or high molar mass, such as PMMA, PS, PC, PIM; 2) cellulose and cellulose esters; 3) polyacrylic acid and polyacrylic acid / polyacrylate copolymers; 4) polyacrylamide; 5) polyethylene oxide; 6) polyurethane. Examples of rheology modifiers (non-exhaustive list): 1) inorganic (nano) particles, such as pyrogenic silicic acid, natural and synthetic clay minerals, sheet silicates, glass; 2) organically modified inorganic (nano) particles; 3) organic molecules, oligomers and polymers (urea derivatives, polysaccharides, polyacrylic acid, polyacrylates, polyamides, polyethers, polyurethanes, polyurea derivatives); and 4) urea-modified polyacrylates, polyethers, polyamides and polyurethanes. Examples (non-exhaustive) of commercial organic rheology modifiers that can be used: RHEOBYK 410, RHEOBYK 420, RHEOBYK 430, RHEOBYK 440, BYK-LP R21675, RHEOBYK 7410CA, RHEOBYK 7420CA, RHEOBYK 7420ET (all available from BYK-Chemie GmbH, 46486 Wesel (Germany)), JL-106 (available from Bomar Chem, 51 Greenwoods Rd, Torrington, CT 06790).

[0059] For any rheology modifier, when selected and / or used, for example, considering its chemical and / or physical properties, concentration, etc., it is preferred that it does not or hardly causes turbidity in the starting material and / or the cured material after optical treatment.

[0060] At this point, it should be noted that, in general, in particular in the wavelength range between 370 nm and 800 nm, more particularly between 400 nm and 800 nm, more particularly between 450 nm and 800 nm, more particularly at 600 nm, the transmittance of the starting material in the region of the irradiation light of the first wavelength and / or in the region of the irradiation light of the second wavelength is usually at least 10%, in particular at least 20%, more particularly at least 30%, more particularly at least 40%, more particularly at least 50%, more particularly at least 60%, more particularly at least 70%, more particularly at least 80%, more particularly at least 90%, more particularly at least 95%, more particularly at least 99%. In this case, the optical transmittance is related to an optical path length corresponding to 10 mm under the Beer-Lambert law.

[0061] At this point, it should be noted that, in general, in particular in the wavelength range between 370 nm and 800 nm, more particularly between 400 nm and 800 nm, more particularly between 450 nm and 800 nm, more particularly at 600 nm, the optical element generally has a transmittance of at least 10%, in particular at least 20%, more particularly at least 30%, more particularly at least 40%, more particularly at least 50%, more particularly at least 60%, more particularly at least 70%, more particularly at least 80%, more particularly at least 90%, more particularly at least 95%, more particularly at least 99% in the region of illumination light of the first wavelength and / or of illumination light of the second wavelength. In this case, the optical transmittance is related to an optical path length corresponding to 10 mm under the Beer-Lambert law.

[0062] In this document, the terms "transparency" and "transmittance" may be considered synonymous.

[0063] Typically, the starting material will exhibit non-Newtonian rheological properties. Such rheological properties facilitate the fabrication of an object under illumination of at least two different wavelengths, wherein the object remains in a fixed position within the working volume during fabrication, or does not move or minimally moves within the working volume. Such minimal movement may be associated with displacement of the object during formation within the working volume, which displacement is acceptable for accurate production of the object. Such rheological properties may also facilitate separation of a partially produced object from the working volume when a mechanical load is applied. Under mechanical load or shear, the viscosity or apparent viscosity of the non-Newtonian starting material may drop to a value (e.g., a constant shear viscosity) that is lower than a static value (e.g., a zero shear viscosity or a yield stress), thereby allowing the starting material to more easily flow (flow away) and separate from the object. Examples of such non-Newtonian rheological behaviors include pseudoplastic behavior, Bingham behavior, shear thickening behavior, and shear thinning behavior.

[0064] The starting material may have non-Newtonian rheological properties, for example, one or more reactive components (e.g., polyurethane acrylate oligomers, polyurethane methacrylate oligomers, acrylated or methacrylated polyurethanes, acrylated or methacrylated polyurethane ureas, acrylated or methacrylated polyesters, acrylated or methacrylated polyamides, acrylated or methacrylated functionalized block copolymers, alkenyl or alkynyl functionalized polyurethane oligomers, alkenyl or alkynyl functionalized polyurethanes, alkenyl or alkynyl functionalized polyurethane ureas, alkenyl or alkynyl functionalized polyesters, alkenyl or alkynyl functionalized polyamides, alkenyl or alkynyl functionalized block copolymers, thiol functionalized polyurethane oligomers, thiol functionalized polyurethanes, thiol functionalized polyurethane ureas, thiol functionalized polyesters, thiol functionalized polyamides, thiol functionalized block copolymers) may be additionally provided in the photocurable starting material components, and / or one or more non-reactive additives (e.g., but not limited to, one or more thixotropic agents and / or rheology modifiers) may be further added. In order to impart non-Newtonian rheological properties to the starting material, the reactive component or components and the amount added can in principle be freely selected in order to obtain specific rheological properties of the starting material.

[0065] For example, the viscosity or constant shear viscosity of the starting material can be less than 30,000 mPas, less than 20,000 mPas, less than 10,000 mPas, less than 5000 mPas or less than 1000 mPas. Constant shear viscosity refers to the viscosity plateau value reached under unidirectional constant shear, such as the viscosity value after the thixotropic network breaks. The preferred constant shear viscosity is less than 30,000 mPas, more preferably less than 10,000 mPas, and most preferably less than 1000 mPas. The viscosity under constant shear can be measured at ambient temperature (such as room temperature), printing temperature or different temperatures (such as increasing or decreasing). Measuring at printing temperature is helpful to determine whether the starting material is suitable for printing.

[0066] Constant shear viscosity can be measured under continuous shear at a constant rate, for example, a shear rate of about 0.00001s -1 To about 1000s -1 .

[0067] As mentioned above, the starting material may include at least one additive. As mentioned above, examples of additives include fillers, thixotropic agents or rheology modifiers, defoamers, stabilizers, oxygen scavengers, non-reactive solvents or diluents, and dyes. For each additive, it can be a single additive or a mixture of multiple additives. Therefore, the thixotropic agent can include a single thixotropic agent or a mixture of two or more thixotropic agents.

[0068] The additives are preferably selected so as not to adversely react with other components or additives contained or possibly contained in the starting materials.

[0069] As mentioned above, the additive can be a filler or at least include a filler. The amount of filler can be greater than 0% by weight to less than 90% by weight, wherein the amount is generally determined by the intended end-use properties of the filler and the object produced. Advantageously, the choice of filler can retain the optical properties of the starting material, particularly transparency or transmittance, for example, the particle size of the filler can be selected to be much smaller than the excitation wavelength, or the refractive index of the filler and the refractive index of the starting material as the matrix are matched to each other to prevent or at least reduce unnecessary scattering effects. The use of fillers can especially change one or more properties of the starting material or object, such as stiffness, strength, viscosity, impact strength, creep strength, fatigue strength, mechanical rebound, mechanical loss tangent, glass transition temperature, thermal decomposition temperature, thermal conductivity, heat resistance, hygroscopicity, electrical conductivity, static dissipation, dielectric constant and loss tangent, density, refractive index, light dispersion, opacity to ionizing radiation and resistance to ionizing radiation. As mentioned above, fillers can also be used to change the properties of the starting material or object, such as rheological properties (such as viscosity and thixotropy) and optical properties (such as refractive index). Examples of fillers include, but are not limited to, silica, alumina, zirconium dioxide, silicate glass (e.g., soda lime glass, borosilicate glass, soda silicate glass, lead glass, aluminosilicate glass, barium glass, thorium glass, glass ceramics, chalcogenide glass, glass microspheres and microbubbles); nanoclays (e.g., synthetic hectorite, montmorillonite, bentonite, kaolinite, hectorite and halloysite); calcium phosphate minerals (e.g., hydroxyapatite), mineral fillers (e.g., chalk, mineral dust, coal slag dust, fly ash, hydraulic cement, loess, limestone, kaolin, talc and wollastonite). Examples of particle size ranges include less than 10 μm, less than 1 μm, 10 nm to 500 nm, 10 nm to 90 nm, 40 nm to 70 nm. Smaller particle sizes, especially particle sizes less than about 100 nm, may be more conducive to achieving high optical transparency or transmittance of the starting material and facilitate printing. Controlling the distribution of particle sizes, e.g., monodisperse, bimodal or trimodal size distribution, may be advantageous for controlling rheological properties, increasing the weight fraction of filler, or influencing the properties of the starting material and / or the object in a desired manner.

[0070] In one embodiment, the additive can be a substance that adjusts the refractive index of the liquid or paste component to the filler. For example, polyethylene glycol (PEG) or its derivatives, in particular polyethylene glycol diacrylate (PEGDA) or its derivatives. Substances for adjusting the refractive index also include halides, in particular iodides. When using such substances, fillers with non-adjusted refractive index or fillers with a particle size of more than 50nm can be used, and the particle size is particularly more than 100nm, especially more than 500nm, especially more than 1μm, and especially more than 10μm.

[0071] Other examples of additives are thixotropic agents and rheology modifiers. Suitable thixotropic agents or rheology modifiers are, for example, urea derivatives; modified urea compounds such as Rheobyk 410 and Rheobyk-D 410 (available from BYK-Chemie GmbH); pyrogenic metal oxides (also known as pyrogenic metal oxides), including but not limited to pyrogenic silicic acid, pyrogenic clay; zirconium dioxide; precipitated metal oxides, including but not limited to precipitated silicic acid, precipitated clay; unmodified and organically modified sheet silicate clays; dimer and trimer fatty acids; polyether phosphates; oxidized polyolefins; mixtures of oxidized polyolefins and polyamides; alkali-soluble / swellable emulsions; cellulose ethers; hydrophobically modified alkali-soluble emulsions; hydrophobically modified polyurethanes based on ethylene oxide; sucrose benzoate; ester-terminated polyamides; tertiary amide-terminated polyamides; polyalkylene oxide-terminated polyamides; polyether amides; acrylamidomethylcellulose ester polymers; polyethylene imines; polyureas; organoclays; hydrogenated castor oil; organic alkali salts of clay minerals (such as montmorillonite) and other silicate materials; aluminum, calcium and zinc salts of fatty acids (such as lauric acid and stearic acid).

[0072] Thermoreversible gelling agents, such as ester-terminated polyamides, tertiary amide-terminated polyamides, polyalkoxy-terminated polyamides, and polyetheramides, and combinations thereof, can be used as thixotropic agents. Examples of such thixotropic agents include Crystasense LP1, Crystasense LP2, Crystasense LP3, Crystasense MP, Crystasense HP4, Crystasense HP5, Rheoptima X17, Rheoptima X24, Rheoptima X38, Rheoptima X58, Rheoptima X73, and Rheoptima X84 (available from Croda). Crystasense HP-5 is a preferred thixotropic agent.

[0073] In addition, metal oxides (particularly metal oxides that have been surface treated to provide specific dispersibility compatible with the starting material) are also examples of thixotropic agents. The content of the thixotropic agent in the starting material can be, for example, about 0.05% by weight to about 15% by weight, particularly about 0.5% by weight to about 15% by weight, more particularly about 0.5% by weight to about 10% by weight, and more particularly about 1% by weight to about 10% by weight. In principle, the amount of the thixotropic agent is preferably effective in limiting the movement of one or more regions of the three-dimensional object or three-dimensional object in the starting material during the production process. Preferably, the content of the thixotropic agent should be able to effectively limit the movement of objects suspended in the working volume (not in contact with the container surface) during the molding process. In this case, the direction and / or position of the object in the working volume during the production process remain (substantially) unchanged.

[0074] The defoamer mentioned further above may be BYK 1798, a silicon-based defoamer (available from BYK-Chemie GmbH), which can be used to eliminate bubbles generated during handling and processing.

[0075] In addition, generally, the starting material may contain water. Therefore, the starting material can be an aqueous solution. The proportion of water can be between 5% by weight and 99.9% by weight, particularly between 30% by weight and 99.9% by weight, more particularly between 40% by weight and 99.9% by weight, more particularly between 50% by weight and 99.9% by weight, more particularly between 60% by weight and 99.9% by weight, more particularly between 70% by weight and 99.9% by weight, more particularly between 80% by weight and 99.9% by weight, more particularly between 90% by weight and 99.9% by weight. In these embodiments, the corresponding additives, such as rheology modifiers, such as polyacrylic acid, gelatin, etc., are soluble in water or water / monomer or water / oligomer mixtures, or are miscible with water or water / monomer or water / oligomer mixtures. In particular, it should be ensured that the additive has a corresponding solubility in water or with water in the temperature range of 20 to 40°C, in particular in the temperature range of 25°C to 37°C, or in the temperature range of 20°C to 30°C, or in the temperature range of 35°C to 40°C.

[0076] The corresponding aqueous starting materials, in particular those containing one or more water-soluble and / or water-miscible additives, are selected in particular in their composition to be transparent. This is to be understood in particular as meaning that the starting material (including the additives) has a transmittance of at least 30%, in particular at least 50%, more particularly at least 80%, more particularly at least 90% in the wavelength range, in particular between 370 nm and 800 nm, in particular between 400 nm and 800 nm, more particularly between 450 nm and 800 nm, in the region of the irradiation light of the first wavelength and / or in the region of the irradiation light of the second wavelength. In this case, the transmittance is related to an optical path length of 10 mm corresponding to the Beer-Lambert law. In particular, the corresponding transmittance should be ensured in the temperature range of 20° C. to 40° C., in particular between 25° C. and 37° C., or between 20° C. and 30° C., or between 35° C. and 40° C.

[0077] Corresponding aqueous starting materials, in particular those containing one or more water-soluble and / or water-miscible additives, are in particular selected in their composition to have a pH value in the range of 5 to 10, in particular between 6 and 9, more particularly between 7 and 8, in particular 7.4. In this way, undesirable precipitation of the additives and / or the formation of undesirable emulsions can be prevented or at least reduced. The pH value can be set or stabilized by adding a buffer (such as phosphate-buffered saline, PBS for short). In particular, the corresponding pH value should be ensured in the temperature range of 20°C to 40°C, in particular 25°C to 37°C, or 20°C to 30°C, or 35°C to 40°C.

[0078] Generally speaking, it is advantageous for the printing process if the pH value of the starting material is above 8, in particular above 8.5, and more in particular above 9. The corresponding pH value provides a large printing or processing window. In addition, the corresponding pH value generally has a positive influence on the rheological properties and optical properties (especially transparency) of the starting material.

[0079] The starting material may contain one or more of the following gelling agents, which can also serve as rheology modifiers as a further conceivable additive. The gelling agent may be a polymer, in particular a polymer comprising a carboxylic acid, such as polyacrylic acid or crosslinked polyacrylic acid; or polyvinyl alcohol or a derivative thereof; or a polysaccharide or a derivative thereof; or a peptide or protein or a derivative thereof, in particular gamma-carrageenan; or gelatin or a derivative thereof. The addition of a gelling agent or a general rheology modifier is preferred when the starting material contains low-viscosity monomers or oligomers. The addition of a rheology modifier is particularly advantageous if the starting material contains a polyethylene glycol diacrylate derivative (PEGDA), in particular if the content of the polyethylene glycol diacrylate derivative (PEGDA) in the starting material is at least 10% by weight, in particular at least 20% by weight, in particular at least 30% by weight, in particular at least 40% by weight, in particular at least 50% by weight, in particular at least 60% by weight, in particular at least 70% by weight, in particular at least 80% by weight, in particular at least 90% by weight.

[0080] In one embodiment, light of a first wavelength may first be irradiated into a first layer partial volume with a substantially uniform distribution, and then into a second layer partial volume with a substantially uniform distribution, the substantially uniform distribution involving at least one of the following light parameters: light intensity and light color. In this way, substantially uniform illumination of each layer partial volume may be achieved. In addition, it may be provided that light of a first wavelength first irradiates a first layer partial volume with a substantially uniform distribution, and then irradiates a second layer partial volume with a substantially uniform distribution, the substantially uniform distribution involving at least one of the following light parameters, wherein an inhomogeneous distribution in the first layer partial volume may be different from an inhomogeneous distribution in the second layer partial volume. For example, for light of a first wavelength, a gradient of light intensity may be formed over the width and / or height of the layer partial volume.

[0081] The light of the second wavelength may first be projected onto the first layer partial volume with a substantially non-uniform distribution and then onto the second layer partial volume with a substantially non-uniform distribution, in each case with respect to at least one of the following light parameters: light intensity and light color. While the light of the first wavelength may illuminate the layer partial volumes as uniformly as possible, the light of the second wavelength does not hit the starting material in the layer partial volume uniformly, but rather in a manner corresponding to the non-uniform light distribution of the light projected onto the layer (so that the light of the second wavelength hits the starting material in the layer partial volume) so that the non-uniform light distribution (light parameters) is optically processed accordingly. In this way, a volume outer contour may be formed or produced. Optionally, each layer partial volume may be illuminated by a different non-uniform light distribution (different projections).

[0082] When irradiating the first layer partial volume and / or irradiating the second layer partial volume with light of the first wavelength, a layer partial volume having a layer thickness of at most approximately 1 mm can be irradiated or hit. In addition, a layer partial volume having a layer thickness of at most approximately 500 μm can also be irradiated. In another alternative embodiment, a layer partial volume having a layer thickness of at most approximately 250 μm can be irradiated. The minimum layer thickness of the irradiated layer partial volumes is approximately 10 μm.

[0083] A plurality of optical elements may also be formed (at least partially) from the starting material (by optical processing).

[0084] The forming of the at least one optical element may comprise forming at least one of the following optical elements: an optical lens, an imaging quality lens, an intraocular lens, a lens array, a diffuser, a prism, a grating, a diffractive optical element and an optical waveguide. The intraocular lens may in particular be an accommodating intraocular lens. In particular, a (functional) contact lens may be formed. In other words, according to the method, in particular an optical lens, an imaging quality lens, an intraocular lens (in particular an accommodating intraocular lens), a lens array, a diffuser, a prism, an optical grating, a diffractive optical element or an optical waveguide may be produced.

[0085] In one embodiment, the optical element can be formed with a transmittance of at least 10%, in particular at least 20%, more particularly at least 30%, more particularly at least 40%, more particularly at least 50%, more particularly at least 60%, more particularly at least 70%, more particularly at least 80%, more particularly at least 90% in the range of 300 nm to 2500 nm, preferably 380 nm to 2000 nm, more particularly 400 nm to 1800 nm, most preferably 450 nm to 1600 nm. In another embodiment, the optical element can be formed with a surface roughness (rms value) of at most 100 nm, preferably at most 50 nm, more particularly at most 30 nm, more particularly at most 10 nm. The transmittance is related in particular to the thickness or wall thickness of the optical element or to the optical path length corresponding to 1 mm or 10 mm of the optical element under the Beer-Lambert law. The smallest individual structure size of the optical element can be 0.1 μm to 10 μm.

[0086] In this regard, it should generally be noted that the optical element referred to in the present application is any element having a transmittance of at least 10%, in particular at least 20%, more particularly at least 30%, more particularly at least 40%, more particularly at least 50%, more particularly at least 60%, more particularly at least 70%, more particularly at least 80%, more particularly at least 90% in the wavelength range of 300 nm to 2500 nm, preferably 380 nm to 2000 nm, more particularly 400 nm to 1800 nm, and most preferably 450 nm to 1600 nm. The transmittance is usually related to the thickness or wall thickness of the optical element, or to the optical path length corresponding to 1 mm of the optical element under the Beer-Lambert law.

[0087] The optical element may be configured to shape light. In particular, the optical element may be configured to refract, diffract, reflect, scatter, interfere and / or polarize light. The optical element may be configured as at least one of the following optical elements: a spherical lens, an aspherical lens, a freeform lens, a Fresnel lens, a lens array, a diffuser, a prism, a grating, a diffractive optical element, and a light wave.

[0088] The green body may be further processed without photochemical post-curing and / or tempering and / or further processing steps (such as grinding, polishing and / or coating, in particular for forming optical elements with relatively low surface roughness).

[0089] In particular, at least one functional element may be added to the starting material before and / or during the optical treatment. Furthermore, the optical element may be formed at least partially adjacent to the at least one functional element. In particular, the optical element may be formed around the at least one functional element, preferably the optical element is formed to at least partially (in particular completely) surround the at least one functional element.

[0090] The at least one functional element can be arranged at least partially, in particular completely, in the starting material and / or at least partially adjoin the starting material. The at least one functional element can be arranged in the starting material by means of an arrangement device.

[0091] At least one functional element includes at least one of the following elements: an actuator element, a sensor element, an energy element (for providing electrical energy, such as a solar cell), a display screen, a lens holder (lens holder), and other prefabricated optical elements. Additionally or alternatively, at least one functional element may also include at least one optical component, in particular at least one of one or more apertures and filters.

[0092] The at least one prefabricated further optical element can be a lens, a lens array, a grating, a diffractive optical element or an optical waveguide. The optical element can in particular be formed and bonded to the glass fiber and / or the light source.

[0093] The at least one functional element may comprise an optoelectronic component, in particular at least one of a light source, such as an LED chip or a laser diode, and an optical sensor, such as a CMOS or CCD chip.

[0094] The at least one functional element may include at least one electronic component, in particular at least one of an electronic circuit, a resistance sensor, an electronic chip, a battery, a wire and an electrical terminal.

[0095] The at least one functional element may comprise at least one component having terminals on its surface, which preferably can control another electronic functional element inside the component. The at least one functional element may comprise at least one micro pump or mechanical actuator.

[0096] The at least one functional element may have a refractive index that is identical or similar to the starting material, in particular such that light of the first wavelength and / or the second wavelength is not refracted at the interface between the functional element and the starting material. The (functional element) refractive index of the at least one functional element (and / or the (functional element) refractive index when formed) may deviate (relatively) from the refractive index of the starting material by at most 3%, preferably at most 1%, particularly preferably at most 0.3%, particularly preferably at most 0.1%.

[0097] At least one functional element may be non-reflective.

[0098] The method may further comprise final processing of the (at least partially) formed optical element. The method may comprise laser processing and / or mechanical processing of the optical element. Laser processing and / or mechanical processing of the optical element is a possible example of finalizing the (at least partially) formed optical element.

[0099] During the optical treatment, the starting material around the at least one functional element can be irradiated with light of a first wavelength and light of a second wavelength from at least two sides, in particular two different sides, in particular four different sides. The irradiation of at least two sides, in particular two sides, in particular four sides can be performed simultaneously or sequentially. For example, the optical treatment of the functional element can be performed in a first direction and (simultaneously or sequentially) in a second direction different from the first direction. In particular, the functional element can be rotated relative to the light source / light source between the optical treatment in the first direction and the second direction.

[0100] The irradiation can be performed by means of oppositely arranged light sources (of the first wavelength and / or the second wavelength), in particular such that the starting material is located between the oppositely arranged light sources.

[0101] A plurality of light sources may be used to illuminate the light of the first wavelength and / or the light of the second wavelength so that the light is preferably irradiated into at least partially overlapping layer partial volumes. At least one functional element may be arranged in the starting volume in a manner that does not hinder or does not hinder as much as possible the beam path of the light of the first wavelength and the second wavelength. In particular, a plurality of light sources may be used to provide the light of the first wavelength and / or the second wavelength so that all partial volumes around the functional element are irradiated.

[0102] Alternatively, light from one light source can be directed into the starting volume by providing light reflecting elements, in particular mirrors, so as to illuminate all local volumes around the functional element. It is also possible to choose to illuminate non-adjacent layer local volumes in sequence, in particular to illuminate a portion of the starting volume in one direction and then illuminate another portion of the starting volume in a different direction (preferably the opposite direction). If it is not possible to illuminate all local volumes around the functional element, the above scheme can be chosen to minimize the local volumes that cannot be reached.

[0103] In particular, light of a first wavelength can be irradiated into the starting material via a mirror ring, wherein the starting material is arranged within the mirror ring and / or along the axis of rotation of the mirror ring. In this way, a circular light segment can be formed for the light of the first wavelength. Light of a second wavelength can be irradiated into the starting material orthogonally to the light segment.

[0104] In one embodiment, the light segment of the first wavelength and the projected image of the second wavelength can both be generated by a (single or integrated) projection device and then irradiated onto / into the receiving container. In this case, a light reflecting element, in particular a mirror, can be provided to separate the light segment from the beam axis of the projection device and to cause the light segment to irradiate laterally onto the projected image of the receiving container.

[0105] In one embodiment, the receiving container can be moved so that the light segment passes through the working volume. The projected image can be clearly imaged in the light segment by means of a variable focal length optical element. In one embodiment, the direction of movement can be changed in the method so that different parts of the working volume are solidified in different directions. In another embodiment, the receiving container remains stationary while the light segment is moved, for example by dividing the display element of the projection device (e.g. an LC display or a DM display) into a central area (generating the projected image) and two laterally mounted areas (generating the light segment). To this end, the pixels of the display element are driven by controlling the optical transmission or reflection of the display element to achieve a lateral movement of the light segment. In this case, the central area of ​​the display element can be irradiated with a first wavelength and the outer area of ​​the display element can be irradiated with a second wavelength.

[0106] The material to be processed can be irradiated with light of (at least) a third wavelength, wherein the third wavelength is different from the first wavelength and the second wavelength. In this case, for example, the light of the third wavelength can be irradiated onto the local volume of the layer currently being processed, simultaneously with the irradiation with light of the second / first wavelength or staggered in time with the irradiation with light of the second / first wavelength. For this purpose, a projection device or a further projection device can be used to selectively limit the light irradiated onto the local volume of the current layer. Thus, for example when using multicolor multiphoton polymerization, the material treatment chemical / physical processes that are initiated or occur in the working volume of the material to be processed can be (additionally) influenced.

[0107] The following is an example to explain the specific implementation of this method:

[0108] In one embodiment, the starting material can be stirred for a certain period of time, especially after being filled into a container defining a working volume, the volume can be stirred for at least one hour, especially for at least six hours, more especially for at least twelve hours, more especially for at least eighteen hours, more especially for at least twenty hours. As mentioned above, stirring the starting material accordingly can enable the starting material to achieve the desired rheological properties, especially the desired yield strength.

[0109] In one embodiment, the starting material may be subjected to at least one step of removing impurities (especially particulate impurities) before irradiation, especially before being loaded into a container with a defined working volume, wherein the step especially comprises filtering the starting material through a filtering device. In this way, any impurities that have a negative impact on the optical properties of the optical element to be produced can be removed, thereby having a corresponding positive impact on the quality of the optical element to be produced.

[0110] In a further embodiment, further processing of the green body, in particular post-curing of the green body, is carried out under a protective gas environment, in particular under an argon, carbon dioxide or nitrogen environment, so that the optical element is at least partially formed from the green body, in particular completely formed from the green body. Surprisingly, further processing of the green body, in particular post-curing of the green body, in particular photochemical and / or thermal post-curing of the green body, under a corresponding protective gas environment can achieve a better component surface. In particular, this method can avoid or at least reduce undesirable sticky component surfaces.

[0111] In a further embodiment, further processing of the green body may include photochemically post-curing the green body by at least one additional photoinitiator, wherein the additional photoinitiator is configured to photochemically react at a wavelength different from the first wavelength and the second wavelength, thereby achieving photochemical post-curing of the green body. Therefore, it is very advantageous to photochemically post-cure the green body with an additional photoinitiator that has no or minimal absorption of the first wavelength and the second wavelength, thereby ensuring that the additional photoinitiator does not or hardly reacts when the starting material is irradiated with light of the first wavelength and the second wavelength.

[0112] An example of a corresponding additional photoinitiator is an α-diketone, in particular camphorquinone, or the corresponding additional photoinitiator may comprise at least one α-diketone, in particular camphorquinone. In practice, the corresponding additional photoinitiator has proven to be particularly effective if the first wavelength is less than 400 nm, in particular 375 nm, and the second wavelength is 500 nm or greater than 500 nm.

[0113] In general, it is also possible to use another photoinitiator which has an absorption maximum in the wavelength range between the first and second wavelengths. An example of a corresponding additional photoinitiator is an α-diketone, in particular camphorquinone, which has an absorption maximum of about 470 nm. In one embodiment of the method, the first wavelength is below 420 nm and the second wavelength is above 500 nm, so that the absorption maximum of camphorquinone is between the two.

[0114] In general, additional photoinitiators may be used, which have an absorption wavelength range between 400 nm and 600 nm. As described above, the absorption maximum of the additional photoinitiator may be between the first wavelength and the second wavelength.

[0115] In general, additional photoinitiators may be used which change their optical properties, in particular fade, when irradiated with light having a wavelength between the first wavelength and the second wavelength.

[0116] In general, additional photoinitiators may be used whose extinction coefficient at the first wavelength and / or the second wavelength is less than 10,000 1 / mol / cm, in particular less than 5000 1 / mol / cm, more particularly less than 1000 1 / mol / cm, more particularly less than 500 1 / mol / cm, more particularly less than 300 1 / mol / cm, more particularly less than 100 1 / mol / cm, more particularly less than 50 1 / mol / cm, more particularly less than 10 1 / mol / cm, more particularly less than 1 1 / mol / cm.

[0117] Additional photoinitiators may be: α-diketones, such as diacetyl, 3,4-hexanedione.

[0118] Alternatively or additionally, the additional photoinitiator may be: an aromatic α-diketone, such as benzil or a benzil derivative, or acenaphthenequinone.

[0119] Alternatively or additionally, the additional photoinitiator may be a cyclic α-diketone, such as camphorquinone or 1,2-cyclohexanedione.

[0120] Alternatively or additionally, the additional photoinitiator may also be: an aliphatic α-diketone, such as camphorquinone, diacetyl or 3,4-hexanedione.

[0121] Generally speaking, the specific concentration of the additional photoinitiator is 0.0001 to 10% by weight, in particular 0.01 to 2% by weight, more in particular 0.1 to 2% by weight, and more in particular 0.1 to 1% by weight.

[0122] In addition, it is also very advantageous to use a photoinitiator that can be irradiated with visible light, in particular with visible light in the wavelength range between 400 nm and 600 nm, preferably between 420 nm and 500 nm. Since the additional photoinitiator as described above can be excited between the first wavelength and the second wavelength and hardly exhibits any absorption at the first wavelength and the second wavelength, the additional photoinitiator does not or hardly influences the absorption of the starting material at the first wavelength and the second wavelength, so that the first wavelength and the second wavelength have a large penetration depth when forming the object or the green body, thereby generating the largest possible installation volume and preventing or at least reducing undesirable secondary reactions with the first wavelength or the second wavelength. In addition, a uniform post-curing of the object can be achieved even within the working volume. In this way, cracks on the surface of the object can be prevented or at least reduced, which would not occur if the additional photoinitiator was irradiated with light with a wavelength lower than the first wavelength.

[0123] In one embodiment, post-processing, in particular post-curing, of the object, in particular when using a corresponding additional photoinitiator, may comprise irradiating the object with light having a wavelength between the first wavelength and the second wavelength. As described above, this may prevent or at least reduce the appearance of cracks on the surface of the object, which would not occur if the additional photoinitiator was irradiated with light having a wavelength lower than the first wavelength. This may constitute an independent aspect of the present invention.

[0124] In one embodiment, the green body may be irradiated with light having a wavelength between a first wavelength and a second wavelength, wherein absorption is reduced at at least one wavelength between the first wavelength and the second wavelength. In this way, during the irradiation, the penetration depth of the light used for post-treatment may be increased, so that in particular the interior of the green body may be effectively post-treated, thereby obtaining a uniformly cured optical element. This may optionally constitute an independent aspect of the present invention.

[0125] In one embodiment, the green body can be irradiated with light having a wavelength between a first wavelength and a second wavelength, wherein the absorption is reduced in a wavelength range between the first wavelength and the second wavelength. In this way, during the irradiation process, the penetration depth of the light used for post-treatment can be increased, so that in particular the interior of the green body can be effectively post-treated, thereby obtaining a uniformly cured optical element. This can optionally constitute an independent aspect of the present invention.

[0126] In one embodiment, the green body may be irradiated with light having a wavelength between a first wavelength and a second wavelength, wherein absorption is reduced at the irradiation wavelength between the first wavelength and the second wavelength. In this way, during the irradiation process, the penetration depth of the light used for post-treatment may be increased, so that in particular the interior of the green body may be effectively post-treated, thereby obtaining a uniformly cured optical element. This may optionally constitute an independent aspect of the present invention.

[0127] The further treatment of the green body may include treating the green body with a solvent and / or a monomer, in particular for washing the green body, wherein the molar mass of the solvent and / or the monomer used is greater than or equal to 200 g / mol. The use of a solvent or a monomer with a correspondingly higher molar mass can prevent the solvent or the monomer from penetrating into the green body, thereby avoiding that the properties of the green body are affected.

[0128] A specific example of a corresponding solvent or monomer is tripropylene glycol monomethyl ether having a corresponding molar mass.

[0129] In another embodiment, further processing of the green body may include treating the green body with a solvent and / or a monomer, in particular for washing the green body, wherein a highly volatile solvent and / or a highly volatile monomer is used. Using a highly volatile solvent or monomer can accelerate the drying process of the green body, thereby making the method more efficient.

[0130] Specific examples of the corresponding low molecular weight solvents or monomers are alcohols such as ethanol or isopropanol.

[0131] In another embodiment, a starting material that does not contain inorganic and / or organic particles can be used. In particular, a starting material that does not contain inorganic and / or organic particles with a diameter greater than 50 μm can be used. This will also have a positive impact on the quality of the optical element produced according to the method, in particular because the inorganic and / or organic particles or nanoparticles cannot damage the optical element. However, for example, in order to set the required refractive index, the starting material can also contain inorganic and / or organic nanoparticles, in particular particles with a diameter less than 50 nm. The concentration of the corresponding nanoparticles can be between 0.1% by weight and 5% by weight, in particular between 0.3% by weight and 2% by weight, in particular between 0.5% by weight and 1.5% by weight. The corresponding nanoparticles can be nanoparticles such as SiO2, ZrO2 and TiO2.

[0132] In another embodiment, starting materials containing only organic components can be used. This can also have a positive effect on the quality of the optical element produced according to the method, in particular since it is not possible to damage the optical element due to inorganic components.

[0133] In another embodiment, starting materials can be used which do not contain organic polymers. This can also have a positive effect on the quality of the optical element produced according to the method, in particular because there will be no influence of organic polymers which could lead to undesired phase separations associated with polymerization.

[0134] In another embodiment, the optical element to be produced can have a main extension plane, which is a planar geometry. This applies to optical lenses, etc. In this case, the construction or printing direction of the optical element is preferably selected to be at an angle, in particular at a right angle, to the main extension plane. In this way, it is possible to prevent or at least slow down the sedimentation of the green body in the starting material, which may have a negative impact on the quality of the optical element to be produced.

[0135] In principle, all embodiments can choose a production or printing direction from top to bottom, or vice versa. Thus, the production or printing direction can be oriented along a vertical axis.

[0136] In another embodiment, the first wavelength may be less than or equal to 400 nm, in particular less than or equal to 375 nm. Alternatively or additionally, the second wavelength may be 405 nm.

[0137] In another embodiment, the starting material and / or the photoinitiator and / or the coinitiator may be free of amine bonds, or the starting material and / or the photoinitiator and / or the coinitiator may contain one or more amine bonds in an amount of less than 10% by weight, in particular less than 5% by weight, more in particular less than 4% by weight, in particular less than 3% by weight, in particular less than 2% by weight, in particular less than 1% by weight, in particular less than 0.5% by weight, in particular less than 0.25% by weight, in particular less than 0.1% by weight. This may also have a positive effect on the quality of the optical element produced according to the method, in particular because undesired interactions of the corresponding amine bonds with the starting material, which could have a negative impact on the component quality of the produced optical element, may be prevented. In particular, undesired coloration or discoloration, in particular undesired yellowing, of the optical element to be produced may be prevented or at least reduced by this method.

[0138] In another embodiment, at least one first illumination device may be used, which is configured to illuminate light of a first wavelength into the working volume so as to generate at least one first light projection in the working volume, wherein the at least one first light projection comprises a plurality of light beams, and the plurality of light beams pass through the working volume in at least one light plane. In addition, at least one light modulation device may be used, which is associated with the at least one first illumination device, wherein the at least one light modulation device is configured to modulate the volume extension direction of two or more light beams 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.

[0139] At least one light modulator is configured to modulate the volume extension direction of two or more light beams among the multiple 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. At least one light modulator can be configured to actively and / or passively change the volume 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 extend in a non-parallel manner relative to each other. The non-parallel arrangement of at least two light beams in at least one light plane usually causes the at least two light beams to intersect at at least one intersection point in at least one light plane. In particular, multiple intersection points are generated at different positions of at least one light plane, and at these intersection points, at least two light beams intersect. In contrast to the light plane of a conventional volumetric 3D printing device having (basically) parallel (collimated) light beams without intersecting light beams, at least one light modulator of the device described herein allows for purposeful change in the volume extension direction and / or orientation of at least two light beams within at least one light plane, thereby causing at least two light beams to extend in a non-parallel arrangement. At least one light modulator of the device described herein can purposefully change the volume extension direction and / or orientation of at least two light beams within at least one light plane, thereby causing at least two light beams to 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.

[0140] In particular, at least one light modulation device may be configured to influence the optical coherence of the light beams in at least one light plane, in particular to at least partially reduce the coherence, to purposefully change the volume extension direction and / or orientation of at least two light beams so that the at least two light beams extend in a non-parallel arrangement to each other, thereby causing two or more light beams to intersect at one or more intersection points in at least one light plane. Changing the volume extension direction and / or orientation of at least two light beams so that the extension directions of at least two light beams in at least one light plane are not parallel may also result in at least one light plane comprising light beams at an angle to the volume extension direction, which light beams intersect, pass through or propagate in the working volume. In particular, at least two light beams may intersect, pass through or propagate in the working volume at an angle different from 0°. The intersection of at least two light beams at one or more intersection points in at least one light plane may also be manifested as at least two light beams being able to overlap at one or more intersection points.

[0141] Thus, at least one light modulating device may be configured to deflect two or more light beams in at least one light plane, for example by diffraction and / or refraction and / or scattering, such that at least one light plane comprises non-parallel and / or incoherent light beams. The beam steering may comprise a change in the volume extension direction of one or more light beams, in particular relative to the original volume extension direction, such that at least one light plane comprises non-parallel and / or incoherent light beams. This is in contrast to the working principle of conventional light sheet generators, which generate a light sheet using non-intersecting collimated light beams, i.e. light beams with parallel volume extension directions and non-intersecting. Thus, in contrast to conventional light sheets or light segments, which have a basic rectangular shape (determined in the vertical direction by the parallel arrangement of the uppermost and lowermost light beams), at least one light segment modified by the at least one light modulating device may have a non-rectangular basic shape, such as a trapezoid, in the working volume, which basic shape is determined in the vertical direction by the non-parallel light beams.

[0142] In particular, at least one light modulation device may be configured to generate a modified light beam having properties different from a Gaussian beam. Thus, at least one light modulation device may be configured to generate a modified light beam having, for example, a non-Gaussian beam profile. For example, at least one light modulation device may be configured to generate a modified light beam, in particular, such as an Airy beam or a Bessel beam, or a light beam having properties similar to, for example, an Airy beam or a Bessel beam.

[0143] Surprisingly, it has been experimentally shown that the purposeful creation of corresponding intersection points at the intersection of two or more light beams in at least one light plane can lead to a significant reduction in corresponding undesirable artifacts and undesirable properties, such as (quasi-)regular or irregular stripe artifacts or sliding artifacts, so that the produced green body has an optical appearance of being one layer above another, such as is the case in conventional additive manufacturing according to the principles of stereolithography and / or digital light processing and / or volume printing methods such as computational axial lithography (CAL). Thus, at least one light modulation device has a positive influence on the properties of a three-dimensional object produced using the device.

[0144] At least one light modulation device may include one or more optical elements, wherein each optical element is configured to change the original volume extension direction of the incident light beam to generate a light beam having a volume extension direction different from the original volume extension direction. The optical element may be configured as an optical lens or include an optical lens, in particular a microlens, and / or an optical diffuser element, in particular an elliptical diffuser element.

[0145] The light modulator can be mounted so as to be movable, in particular with at least one degree of freedom of translational and / or rotational movement relative to the working volume. In particular, the light modulator can be mounted so as to be movable in at least one volume direction, either uniformly or in an oscillating manner. For this purpose, a corresponding drive device connected to the light modulator can be provided, in particular a drive device external to the associated controller.

[0146] In principle, reflective and / or diffractive optical elements are feasible. It is conceivable that at least one optical element of at least one light modulation device comprises a combination of at least two of the following: one or more optically permeable surfaces, one or more optically reflective surfaces and / or one or more optically diffractive surfaces, a combination of at least two of the optically permeable surfaces, the optically reflective surfaces and / or the optically diffractive surfaces. For example, the corresponding optically permeable surfaces and / or the optically reflective surfaces and / or the optically diffractive surfaces can be formed by or include one or more optically permeable coatings and / or reflective coatings and / or optically diffractive coatings.

[0147] In another embodiment, at least one measure may be taken to change the optical properties of the green body, so as to ensure that the green body has the desired optical properties, in particular the desired transmittance.

[0148] At least one measure may preferably include changing the optical properties of the green body or the optical element, thereby resulting in a reduction in the absorption properties of the green body or the optical element at at least one wavelength in a wavelength range between 300nm and 2000nm, in particular between 350nm and 900nm, and / or resulting in an increase in the light permeability properties of the green body or the optical element at at least one wavelength in a wavelength range between 300nm and 2000nm, in particular between 350nm and 900nm, in particular between 400nm and 800nm.

[0149] Implementing at least one measure for changing the optical properties of the green body may include changing the optical properties of the green body so that the average value of the transmittance or the integral of the transmittance between 300 nm and 2000 nm, in particular between 350 nm and 900 nm, in particular between 400 nm and 800 nm, is reduced by at least 1%, in particular at least 2%, in particular at least 3%, in particular at least 4%, in particular at least 5%, in particular at least 7%, in particular at least 10%, in particular at least 15%, in particular at least 20%, in particular at least 25%, in particular at least 30%, in particular at least 35%, in particular at least 40%, in particular at least 45%, in particular at least 50%, in particular compared to the state of the green body before taking at least one measure. Alternatively or additionally, implementing at least one measure for changing the optical properties of the green body may comprise changing the optical properties of the green body so that an average value of the absorbance between 300 nm and 2000 nm, in particular between 350 nm and 900 nm, in particular between 400 nm and 800 nm or an integral of the absorbance is reduced by at least 1%, in particular at least 2%, in particular at least 3%, in particular at least 4%, in particular at least 5%, in particular at least 7%, in particular at least 10%, in particular at least 15%, in particular at least 20%, in particular at least 25%, in particular at least 30%, in particular at least 35%, in particular at least 40%, in particular at least 45%, in particular at least 50%, in particular compared to a state of the green body before taking at least one measure.

[0150] Therefore, the optical element can generally be understood as having an average or integrated absorptivity per millimeter thickness of less than 0.5, particularly less than 0.3, particularly less than 0.2, and particularly less than 0.1 within a wavelength range between 300nm and 2000nm, particularly between 400nm and 900nm, more particularly between 500nm and 850nm, more particularly between 600nm and 800nm, and more particularly between 650nm and 750nm.

[0151] At least one measure may include changing the optical properties of the green body so that the average or integrated absorption rate per millimeter thickness of the green body is less than 0.5, especially less than 0.3, more especially less than 0.2, more especially less than 0.1 in the wavelength range of 300 nm to 2000 nm, especially 350 nm to 900 nm, more especially 400 nm to 800 nm. In particular, for each wavelength in the wavelength range of 300 nm to 2000 nm, especially 350 nm to 900 nm, especially 400 nm to 800 nm, the average or integrated absorption rate per millimeter thickness of the green body may be less than 0.5, especially less than 0.3, especially less than 0.2, especially less than 0.1.

[0152] In particular, for each wavelength in the wavelength range of 300nm to 2000nm, in particular 350nm to 900nm, in particular 400nm to 800nm, the average or comprehensive absorptivity per millimeter thickness of the optical element can be less than 0.5, in particular less than 0.3, in particular less than 0.2, and in particular less than 0.1.

[0153] At least one measure comprises thermally treating the green body and / or optically treating the green body, in particular irradiating the green body with electromagnetic radiation, and / or chemically treating the green body.

[0154] The heat treatment may comprise aging the green body at a temperature of 50°C to 150°C, in particular 75°C to 125°C, in particular for 1 to 24 hours, in particular for 1 to 20 hours, in particular for 1 to 16 hours, in particular for 1 to 12 hours, in particular for 1 to 8 hours, in particular for 1 to 4 hours, in particular for 1 to 30 minutes.

[0155] The optical treatment may comprise irradiating the green body with electromagnetic radiation having a wavelength of between 350 nm and 1000 nm, in particular between 400 nm and 800 nm, more in particular between 350 nm and 500 nm or between 420 nm and 800 nm, for a duration of in particular between 0.5 minutes and 180 minutes, in particular between 5 minutes and 60 minutes.

[0156] The optical processing of the green body can be performed in the working volume or after the green body is removed from the working volume.

[0157] After the optical treatment, the three-dimensional object can be subjected to a tempering treatment, wherein the temperature control comprises, in particular, heating the green body to a temperature of 50° C. to 150° C. for a period of between 1 minute and 60 minutes, in particular between 5 minutes and 30 minutes.

[0158] The chemical treatment may comprise chemically changing, in particular oxidizing and / or reducing, the chromophore molecules of the green body, in particular the remaining photoinitiator molecules, using at least one chemical modifier, such as an oxidizing agent or a reducing agent, wherein the chromophore molecules have a (visible) color in the visible wavelength spectrum between 380 nm and 750 nm.

[0159] In particular, the at least one chemical modifier may be or include a chlorine-based substance, in particular chlorine, hypochlorite, chlorine dioxide, or an oxygen-based substance, in particular ozone, oxygen, peroxide, perborate, percarbonate, peracetic acid, or chlorine or a chlorine compound.

[0160] At least one chemical modifier can be added to the photopolymerizable material after the green body is formed by placing the three-dimensional object in a solution (especially an organic solution) for a period of time, wherein the solution contains at least one chemical modifier, wherein the at least one chemical modifier migrates from the solution into the three-dimensional object, and possible remaining co-initiator and / or photoinitiator migrates from the three-dimensional object into the solution.

[0161] At least one chemical modifier can be configured to change the properties of the chromophore of the original chromophore molecules, in particular the properties of the chromophore of the remaining photoinitiator molecules, the properties of the chromophore of the photopolymerizable material (starting material) and / or the properties of the chromophore of the green body produced by the photopolymerization process, or at least one chemical modifier is configured to produce a reactant that is configured to change the chromophore molecules of the green body under the influence of electromagnetic energy, in particular thermal energy and / or irradiation energy, in particular to change the chromophore properties of the remaining photoinitiator molecules.

[0162] In all embodiments, the optical treatment of the starting material may also use at least one combined light segment. The corresponding combined light segments can be created as follows: a first light segment is created, which passes through the starting material along an extension axis; a second light segment is created, wherein the first light segment emerging from the starting material is reflected by at least one reflective element, and the reflected light segment thus created passes through the starting material again (essentially) along the extension axis of the first light segment. In principle, each light segment described herein can be a corresponding combined light segment. Likewise, a plurality of combined light segments can also be used, which pass through the working volume from at least two sides, in particular at least three sides, and in particular at least four sides. The extension axes of the individual combined light segments can be oriented relative to each other at any desired angle, for example at an angle of approximately 90° relative to each other.

[0163] The corresponding reflective element may be or include: at least one plane mirror, at least one curved mirror (may be a curved mirror with single curvature or multiple curvatures, such as a double concave mirror), at least one plane convex cylindrical lens, at least one plane concave cylindrical lens, etc. A combination of at least two identical or different reflective elements mentioned above can be envisioned. BRIEF DESCRIPTION OF THE DRAWINGS

[0164] More embodiments will be described in detail below with reference to the accompanying drawings:

[0165] Figure 1 is a schematic top view of an apparatus for processing optically reactive materials;

[0166] Figure 2 yes Figure 1 A side schematic diagram of the device;

[0167] Figure 3a to Figure 3c is a schematic diagram of an arrangement for optically processing a starting material in a receiving vessel;

[0168] Figure 4 is a schematic diagram of a further arrangement for optically processing the starting material in a receiving vessel;

[0169] Figure 5 is a schematic diagram of another arrangement for optically processing starting material in a receiving container using a projection device;

[0170] Figure 6 is a schematic diagram of a further arrangement for optically processing the starting material in a receiving vessel;

[0171] Figure 7 yes Figure 6 A partial schematic diagram of the arrangement shown;

[0172] Figure 8a is a schematic diagram of a further arrangement for optically processing starting material in a receiving container using a mirror ring;

[0173] Figure 8b is a schematic side view of a further arrangement. DETAILED DESCRIPTION

[0174] Figure 1 and Figure 2 The device for optically treating optically reactive materials is shown in top and side views. A receiving container 1 is provided with a working volume 2, which is at least partially filled with a starting material 3. The starting material 3 may consist of one or more substances, which may be solid, liquid or paste-like. During the treatment, the starting material 3 is irradiated in the working volume 2 with light of a first wavelength and light of a second wavelength in an overlapping manner to trigger a photoactivated reaction in a layer partial volume 4.

[0175] The light of the first wavelength is provided by a first light source 5, which in the embodiment shown is configured as a light segment generator. During the processing of the starting material 3, the irradiation area 6 (in the embodiment of the figure, a tapered shape) for the light (light segment) of the first wavelength is moved piece by piece over the working volume 2, thereby processing the starting material 3 in layers. In this way, the layer partial volumes of the working volume 2 previously filled with the starting material 3 (the layered partial volumes of the working volume 2) are irradiated in sequence, in particular the non-overlapping layer partial volumes are irradiated in sequence.

[0176] Depending on the current position of the irradiation area 6 (light segment), light of the second wavelength is projected by means of a projector 7 (projector or projection image) into the layer partial volume currently irradiated with light of the first wavelength. This means that the projection plane or projection volume of the projector 7 is located within the same layer partial volume currently being irradiated with light of the first wavelength. In this way, the light of the first wavelength (light segment) and the light of the second wavelength (light projection) overlap in a volumetric or planar manner on the projection surface of the projector 7 in the macroscopic layer partial volume of the starting material 3 currently irradiated by the light segment (as a partial volume of the working volume 2).

[0177] In this way, in the currently irradiated layered partial volume, at least one material property of the starting material 3 is changed, for example, the original starting material is solidified. In this case, due to the overlap of the two wavelengths of light, a polymerization reaction can be triggered in the starting material 3. For example, a three-dimensionally shaped object can be produced layer by layer in the working volume 2. In this case, the three-dimensional shape of the object can be influenced and determined by means of the projection of the projector 7 in the layer volumes.

[0178] The method can be adjusted to different volumes of starting material 3 . In addition, the method can be optimized between resolution and processing speed.

[0179] The following is a non-limiting example of the production of optical elements: Polyurethane dimethacrylate (Genomer 4247, 350 g), di-trimethylolpropane tetraacrylate (Miramer M410, 49 g), hexanediol diacrylate (Miramer M200, 4 g), N-methyldiethanolamine (4 g) and dual-color photoinitiator 1 (50 mg) are mixed uniformly. The transmittance of the resin is measured with a Cary 50 UV-visible spectrophotometer (Varian) over a light path length of 10 mm and is 69% at λ1=375 nm and >99% at λ2=450-800 nm. The resin thus obtained is transferred to a cuvette and then optically treated as described above. The cured object is removed from the excess starting material and washed several times with isopropyl alcohol or other alcohols. The object can be post-cured by placing the object in a solution of isopropylthioketone (ITX) in ethanol. The object is removed from the solution, dried in air, and then cured by ultraviolet irradiation (365 nm). The transmittance of an optical component with a thickness of 1 mm is greater than 90% in the wavelength range of 450-1600 nm, and the surface roughness is less than 0.04 μm (R a Values ​​are measured according to ISO 4288:199).

[0180] The dual-color photoinitiator 1 has the following structure:

[0181]

[0182] Here is another non-limiting example of producing an optical element: polyurethane dimethacrylate (Genomer 4247, 120 g), tricyclo[5.2.1.02,6]decanemethanol diacrylate (Sartomer SR833S, 22.5 g), N-methyldiethanolamine (7.5 g), RHEOBYK-7420CA (BYK-Chemie GmbH, 5.2 g), 2,6-di-tert-butyl-4-methylphenol (BHT, 0.15 g), camphorquinone (0.15 g) and dual-color photoinitiator 2 (60 mg) were mixed uniformly. The transmittance of the resin was measured at a light path length of 10 mm using a Cary 50 UV-visible spectrophotometer (Varian Company), which was 69% at λ1=375 nm and >99% at λ2=450-800 nm. The resin obtained in this way has non-Newtonian fluid properties. The yield strength of the resin obtained in this way, measured after 24 hours of stirring by means of a rotational rheometer (Netzsch Kinexus Prime lab+ rotational rheometer, 20 mm plate-to-plate geometry, shear stress slope: dσ / dt=0.05 Pa / min, 25° C.), is σ=0.8 Pa. The resin obtained in this way is transferred into a container in the form of a cuvette and optically treated as described above. The cured object is removed from the excess starting material and washed several times with tripropylene glycol monomethyl ether and isopropanol. The object is then removed from the corresponding cleaning solution, dried in air and post-treated by irradiation with blue light (450 nm), in particular for the purpose of curing the object. An optical element with a thickness of 1 mm has a transmittance of more than 90% in the wavelength range of 400-1600 nm and a surface roughness of less than 0.04 μm (R a Values ​​are measured according to ISO 4288:199).

[0183] The dual-color photoinitiator 2 has the following structure:

[0184]

[0185] When an ideal dual-color photoinitiator is used in the starting material 3, only when the two wavelengths are absorbed and (first wavelength and second wavelength), the dual-color photoinitiator will excite the excited state C. For non-ideal photoinitiators, it is also possible to From the intermediate state B to the excited state C. Therefore, the photoinitiator not only transitions to state C at the intersection of the two wavelengths, but also along the wavelength The entire beam of light transitions to state C. Since the photoinitiator has no path from the excited state C back to the ground state A, a large amount of initiator in the excited state C will accumulate in undesirable locations when treating multiple desired target points. The device can make the initiator in the excited state C reach a concentration sufficient to polymerize the starting material in the beam overlap area, while simultaneously transferring the initiator along the first wavelength The concentration of initiator molecules in the excited state C generated by the light beam is minimized. In addition, the device can also reduce the accumulation of photoinitiators in the excited state C in undesirable areas in the volume due to the overlap of light from multiple consecutive target points.

[0186] If the ground state A is displayed at the second wavelength There is an absorption band at the wavelength The photoinitiator transitions to the intermediate state B and then to the excited state C. Therefore, the photoinitiator not only transitions to state C in the overlapping region of the two wavelengths, but also along the wavelength Since the photoinitiator has no path to return from the excited state C to the ground state A, a large amount of initiator in the excited state C will accumulate in undesirable locations when treating multiple desired target points. The device can make the initiator in the excited state C reach a concentration sufficient to produce the desired change in the starting material 3 in the overlapping area of ​​the beam, while converting the initiator along the wavelength The concentration of initiator molecules in the excited state C generated by the light beam is minimized. In addition, the device can also reduce the accumulation of photoinitiators in the excited state C in undesirable areas in the volume due to the overlap of light from multiple consecutive target points.

[0187] The apparatus and method may also be combined with other techniques to limit undesired curing caused by accumulation of initiators in the active state C. In one embodiment, the oxygen concentration in the starting material may be set to change the threshold for curing of the material. In another embodiment, an inhibitor may be added to the starting material to change the threshold for curing of the material.

[0188] Further aspects of the apparatus for optically treating the starting material 3 will be described below.

[0189] The starting material 3 may be contained in a transparent container (receiving container 1) having at least two optically flat inlet windows for receiving the starting material 3 to which the dual-color photoinitiator molecules or other optically active molecules and optionally further additives (such as co-initiators) are added. The light source 5 configured as a light generator with imaging optics generates a wavelength The light segment is irradiated into the working volume 2 through the window of the receiving container 1. The projector 7 with a light source generates an image, which is clearly imaged in the receiving container 1 through the objective lens in the light segment.

[0190] Compared to optical imaging without the receiving container 1, the irradiation light of the second wavelength is refracted at the transition between air and the receiving container 1 and between the receiving container 1 and the starting material 3, which causes a displacement of the focal plane of the projected image (light of the second wavelength). If the working volume of the receiving container 1 is large, the depth of field of the focused projector image may not be sufficient. In this case, the focus correction can be performed continuously during the movement of the light segment in the working volume 2.

[0191] For applications in the field of 3D printing, the refractive index of the starting material 3 can be similar to the refractive index of the material of the receiving container 1. In this case, only the transition between air with a refractive index n1 and the receiving container 1 with a refractive index n2 results in a displacement of the focal plane by an amount Δs given by the following formula:

[0192]

[0193] As the distance d of the light segment (light of the first wavelength) from the entrance window of the receiving container 1 (into which the projector image enters) increases, the focus displacement also increases according to the above formula. The formula relates to the near-axial beam path or to a larger distance between the projector 7 and the receiving container 1. Depending on the embodiment, the displacement compensation can be achieved by a motorized focus adjustment of the fixedly mounted projector 7 or by a motorized positioning of the entire projector 7 relative to the position of the light segment. In the latter embodiment, during the uniform movement of the receiving container 1 through the light segment (layer partial volume) to process the entire working volume 2, the projector 7 undergoes a uniform linear relative movement relative to the fixed light segment.

[0194] As Figure 1 As an alternative to the illustrated construction, the projected image can also enter the working volume 2 through the base or the cover of the receiving container 1 , while the light segment can be coupled perpendicularly to the projected image through one or more side windows.

[0195] Alternatively, the optical segment generator 5 may generate a wavelength The projector 7 generates a wavelength

[0196] If the transition from the intermediate state B to the ground state A is made with a wavelength of The projector 7 will generate a wavelength and or wavelength and In each case the wavelength generated is complementary to the wavelength of the optical band generator.

[0197] One or more light detectors 8a, 8b (cameras or simple photodetectors; see Figure 1 and Figure 2 ) to study the process, i.e. measuring the excitation light emitted by the light segment and optionally the excitation light emitted by the projector 7. In this case, the light segment generator 5 and optionally the projector 7 can emit light of other wavelengths different from the excitation wavelength, which are only used to observe changes in the material properties of the starting material 3 (e.g. polymerization reactions).

[0198] In addition, the fluorescence emitted by the excited photoinitiators in the starting material 3 can also be measured. For example, the intensity of the entire transmitted light or emitted light can be measured by a single photodetector and / or the volume-resolved intensity can be recorded using a camera. The detector can selectively measure only certain wavelengths of light from the projector 7, the light segment generator 5 or the luminescent excited photoinitiators by means of a filter or a beam splitter in front.

[0199] The evaluation of the total or volume-resolved intensity allows the adjustment of a control loop that influences the intensity of the light segment generator, the intensity and image output of the projector, the time control of the illumination sequence and the displacement of the light segment within the receiving container 1. Figure 1 As shown, a control device 9 is provided, which is connected to the light source 5 and the projector 7.

[0200] The light source 5 can use a laser light source, such as a pulsed single-mode diode laser (manufacturer: IBEAM SMART, Toptica Photonics AG, DE) with a wavelength of 375 nm, a maximum output power of 70 mW when operating in continuous wave, and a laser beam diameter of 1.3 mm (@1 / e2). An aspheric POWELL lens (sector angle 300, N-BK7, Edmund Optics GmbH, DE) is used to reshape the laser beam into a divergent laser line. In one embodiment, a plano-convex cylindrical lens (f=300.00 mm, N-BK7, Thorlabs GmbH, DE) with a long focal length is arranged at its rear side and perpendicular to the fan plane, at the position of the container containing the starting material (the distance from the lens is 30 cm), to produce a beam waist with a diameter of about d=100 μm. A plano-convex cylindrical lens (f = 150.00 mm, N-BK7, Thorlabs GmbH, DE) collimates the divergent laser line at a single focal length distance from the POWELL lens, ensuring that the beam is roughly parallel along the optical axis. The height of the collimated light segment is about 8.5 cm. Another cylindrical lens (f = 100.00 mm, N-BK7) is flexibly mounted in front of the container, which converts the beam path into a gradient light segment, thereby reducing the intensity attenuation in the container according to the Beer-Lambert absorption law. Due to the focusing effect, the available height of the light segment in the container area is about 2 cm.

[0201] In order to reshape the laser beam into a diverging laser line, in addition to using a POWELL lens, a suitably arranged rotating polygon mirror or a galvanometer mirror can also be used. In principle, light sources based on LEDs (light emitting diodes) or thermal light sources can also be used instead of lasers.

[0202] The DMD (Digital Micromirror Device from Texas Instruments) based projector (manufacturer: optoma UHD35) has a resolution of 3840 x 2160 pixels and a luminance of 3600 Ansi and can be used as an image projector or projector 7. The projection optics were replaced with a projection objective with a focal length of 90 mm (Braun Ultralit 2.4 / 90, Braun Photo Technik GmbH, Germany), which produces a clear image in the container. A filter glass (GG475, Schott AG, Germany) on the front side is used to select the wavelength. The drive of the projector 7 is realized via the HDMI interface.

[0203] For example, a macrocuvette made of optical glass (inner dimensions 30 mm x 30 mm x 30 mm, Hellma GmbH & Co. KG, Germany) with a transparent, flat inlet window can be used as receiving container 1 .

[0204] Figure 3a to Figure 3c A schematic diagram of an arrangement is shown which comprises a receiving container 1 in which a working volume 2 containing a starting material 3 is provided for optical processing. An arrangement is provided in which a light source 30 is provided. The light source 30 (a light generator for generating a light segment 31) is arranged for irradiating light (light segment) of a first wavelength, and the light source 30 is arranged adjacent to the receiving container 1, in particular on the opposite side of the receiving container 1. Figure 3c In the exemplary embodiment of FIG. 3 , the light source 30 is arranged so as to be rotated around the receiving container 1 having the working volume 2 , which is schematically illustrated by the arrow 32 .

[0205] Two or more light sources 30 can be used, which irradiate the working volume 2 from different sides of the receiving container 1 (in particular opposite or non-opposite sides) and generate light segments 31 by superposition of partial light beams, that is, irradiate the local volumes of each layer that are subsequently projected 33.

[0206] In each case, the light segment 31 of the layer partial volume just illuminated is the sum of the individual illuminations at different illumination angles from the light source 30. In order to achieve a uniform intensity distribution of the light segment 31 by superposition of the light from two or more light sources, the individual illuminations may have a Gaussian distribution or a modified non-uniform intensity distribution instead of a uniform intensity distribution.

[0207] exist Figure 4In another embodiment, two or more light segments 40 (layer partial volumes) are generated, and the light segments 40 are incident at a certain angle into the receiving container 1. One or more projections 41 (for simplicity, Figure 4 (not shown) forms a sharp image in the oblique focal plane of a single light segment 40. Thus, multiple layer partial volumes can be processed simultaneously.

[0208] exist Figure 3a to Figure 3c , Figure 4 In the embodiment shown, the receiving container 1 can be moved through the light sections 31 , 40 , or the light sections 31 , 40 can be moved while the receiving container 1 is in a fixed position, in order to successively and ultimately completely process the working volume 2 , wherein layer partial volumes are optically processed one after the other.

[0209] Figure 5 A schematic diagram of another arrangement including a receiving container 1 is shown. A light segment 50 of a first wavelength and a projection image 51 of a second wavelength are both generated by a projection device 52 and then irradiated onto the receiving container 1. An arrangement of light reflecting elements 53, in particular mirrors, ensures that the light segment 50 is separated from the beam axis of the projection device 52 and that the light segment 50 is irradiated into the receiving container 1 perpendicularly to the projection image 51.

[0210] In one embodiment, the receiving container 1 can be moved so that the light beam passes through the working volume 2. The projected image 51 is sharply imaged in the light segment 50 by means of a variable focal length optical element. In another embodiment, the receiving container 1 remains stationary, the light segment 50 is moved, and the display element of the projection device 52 (e.g. an LCD display or a DMD display) is divided into a central area 54 (generating the projected image 51) and two laterally mounted areas 55 (generating the light segment 50). To this end, the pixels of the display element are driven by controlling the optical transmission or reflection of the display element, thereby achieving a lateral movement of the light segment 50. In this case, the central area of ​​the display element is illuminated with a first wavelength and the outer areas of the display element are illuminated with a second wavelength.

[0211] Figure 6 is a schematic representation of a further arrangement for optically processing the starting material 3 in the receiving container 1 . Figure 7 yes Figure 6 A partial schematic diagram of the arrangement shown.

[0212] A light segment 60 is generated in a horizontal plane 61 by a laser beam 62 which enters from above into an immersion tube 63 which is optically transparent to the laser beam 62 and is deflected by a motorized rotating mirror 64 into a receiving container 1 containing the starting material 3. The rotation generates the light segment 60 of a first wavelength. Projection light 66 of a second wavelength shines through a base 65 of the receiving container 1 so that a projection image 67 is clearly formed in the horizontal plane 61 of the light segment 60.

[0213] The bottom of the immersion tube 63 is closed. The motorized rotating mirror 64 and the laser beam path 62 are separated from the starting material 3 in the receiving container 1. When processing the starting material 3, the immersion tube 63 is moved up or down, and thus the level of the light section 60 is moved up or down.

[0214] FIG. 8 is a schematic plan view of a further arrangement for optically processing the starting material 3 in the receiving container 1 ( Figure 8a ) and side view ( Figure 8b ). The laser beam emitted from the laser 80 passes through the galvanometer scanner 81 and is deflected by the lens 82 on the mirror ring 83 to form a circular light segment of the first wavelength. The light of the second wavelength is provided by the projection device 84 and is deflected orthogonally to the light segment into the receiving container 1 by the mirror 85.

[0215] Further aspects of the method of optically treating the starting material 3 are described below.

[0216] The local polymerization of the starting material 3 is carried out by photoexcitation of the photoinitiator, which is carried out layer by layer in the free volume in the receiving container 1 in a sequential method. For this purpose, the desired three-dimensional object needs to be first decomposed into individual layer images (slices) with a defined grid element spacing. By superimposing the light segments from the light source 5 and the individual layer section images of the projector 7, the two-color photoinitiator is excited and changes from the ground state A to the excited state C, thereby starting the local polymerization of the starting material 3. After the illumination sequence of the current layer (layer local volume) is completed, the light excitation is moved in a defined manner by moving the receiving container 1 and / or the light segments and the projector 7 together, and the adjacent layer or any other layer (other layer local volume) is illuminated. For example, the translation of the projection device or the receiving container 1 can be achieved by a suitable stepper motor, and the translation amplitude can be lower than the waist diameter of the light segment to improve the resolution in the movement direction.

[0217] Depending on the starting materials used and the properties of the two-color photoinitiator, various options are available for the time course of the irradiation sequence for each layer partial volume:

[0218] Variant (1): Activate two light sources simultaneously ( and optional ), irradiates at a defined intensity (optionally different intensities) for a predefined irradiation time. Simultaneously, after activation, the system's translation into the next layer begins.

[0219] Variant (2): The first light source 5 (light segment generator) and the projector 7 are operated in a time pulsed manner. The number, duration and intensity of the pulses, as well as the time offset between the starting edges of two pulses, can be freely set within the defined exposure time of each layer partial volume. When a layer partial volume is processed using multiple pulses, each pulse can be associated with a different image of the projector 7. After the exposure time has expired, the next layer partial volume is shifted.

[0220] Variant (3): The first light source 5 (light segment generator) remains continuously activated, while the projector image is switched after a defined exposure time, while the device is translated to the next phase.

[0221] Variant (4): A physically possible combination of variants (1), (2) and (3).

[0222] The volumetric method described herein generates the desired three-dimensional object by polymerizing the starting material 3 in layers within the working volume 2, but the basic structure of the starting material 3 remains unchanged. This is an advantage compared to methods that can only process the starting material in mutually separated layers. In principle, the layered illumination method is faster than the method of polymerizing the starting material point by point.

[0223] Since the light segment is enlarged, a larger area of ​​the working volume 2 can be processed simultaneously, which is faster, but this means a reduction in resolution.

[0224] The creation of the light segment by the source 5 requires a coupling between the minimum waist diameter and the beam divergence, which results in a broadening of the beam at the edge of the volume. Thus, either a uniform average resolution is produced along the light segment, or a higher resolution is generated in the waist region with a greater resolution falloff at the edge region.

[0225] Since the layers farther from the projector 7 can be processed earlier in the time course, it is avoided that the already cured layers affect the light (the light of the second wavelength) that propagates the projector image.

[0226] Due to the movement of the light segments, a local volume of each layer is only treated once, resulting in a defined energy dose. This effectively prevents polymerization in undesired areas when using non-ideal two-color photoinitiators.

[0227] If the kinetics of the reaction between the photoinitiator molecules and the starting material 3 initiated by light irradiation are well understood, then purposeful control of the relative timing of the light pulses and appropriate selection of the intensities of the two wavelengths will allow for better discrimination between desired and undesired polymerization reactions in the working volume 2. Thus, artifacts and resolution degradation resulting from non-ideal dual-color photoinitiators can be reduced.

[0228] The features disclosed in the above description, claims and drawings for implementing various embodiments may be used alone or in any combination.

[0229] The various features of the present invention are further described by way of example in the following aspects:

[0230] 1. A method for producing an optical element by processing an optically reactive material, comprising:

[0231] Providing a starting material (3) which is optically reactive and fills the working volume (2);

[0232] The starting material (3) in the working volume (2) is optically treated by irradiating light of a first wavelength and light of a second wavelength different from the first wavelength, wherein the first wavelength and the second wavelength are provided by an irradiation device, wherein at least one material property of the starting material is changed by the optical treatment, and the optical treatment comprises the following steps:

[0233] irradiating a first layer partial volume of the working volume (2) filled with the starting material (3) with light of the first wavelength;

[0234] irradiating the first partial volume of the working volume (2) with light of the second wavelength, wherein the light of the second wavelength is projected into the working volume (2) by means of a projection device in such a way that only the first partial volume is fully or partially illuminated;

[0235] irradiating a second partial volume of the working volume (2) filled with the starting material (3) with light of the first wavelength, the second partial volume being different from the first partial volume;

[0236] The second layer partial volume of the working volume (2) is illuminated with light of a second wavelength. In this case, the light of the second wavelength is projected into the working volume (2) by a projection device (7) in such a way that only the second layer partial volume is fully or partially illuminated; the previous steps are repeated to perform layered optical processing on the starting material (3) in the working volume (2) until the volume of the starting material (3) to be processed is optically processed and the volume of the starting material (3) to be processed is fully or partially surrounded by the working volume (2). In this process, a green body is formed from the starting material (3); the green body is further processed so that an optical element is at least partially formed from the green body.

[0237] 2. The method according to aspect 1, wherein further processing of the green body comprises at least one of the following steps: removing the green body from the starting material, treating the green body with a solvent and / or a monomer; drying the cleaned green body; and photochemically and / or thermally post-curing the green body.

[0238] 3. The method according to aspect 2, wherein the solvent and / or the monomer comprises a thermal initiator and / or an additional photoinitiator, wherein the thermal initiator and / or the additional photoinitiator preferably reacts at only one wavelength.

[0239] 4. The method according to at least one of the preceding aspects, wherein the further processing of the green body comprises at least one of the following steps:

[0240] - photochemically post-curing the green body, tempering the green body, grinding the green body, polishing the green body and coating the green body.

[0241] 5. A method according to at least one of the preceding aspects, wherein light of a first wavelength and light of a second wavelength are irradiated simultaneously and together into a first layer local volume or a second layer local volume at least during a time overlap, wherein preferably, the light of the first wavelength is irradiated along a first irradiation direction and the light of the second wavelength is irradiated onto the starting material (3) in the working volume (2) along a second irradiation direction extending perpendicularly to the first irradiation direction.

[0242] 6. The method according to any of the preceding aspects, wherein multicolor multiphoton polymerization is induced in the starting material (3) by optical treatment, thereby causing a change in at least one material property of the starting material (3).

[0243] 7. The method according to at least one of the preceding aspects, wherein the starting material comprises a transparent organic polymer and / or an inorganic / organic polymer composite material, said starting material being preferably cured by phototreatment.

[0244] 8. The method according to at least one of the preceding aspects, wherein the viscosity of the starting material is 10 2 mPa s to 10 7 mPa s.

[0245] 9. A method according to at least one of the preceding aspects, wherein the formation of the optical element comprises the formation of at least one of the following optical elements: an optical lens, an imaging quality lens, an intraocular lens, a lens array, a diffuser, a prism, a grating, a diffractive optical element, and a light wave.

[0246] 10. The method according to at least one of the preceding aspects, wherein the starting material (3) comprises at least one functional element and at least a part of the optical element is formed adjacent to the at least one functional element.

[0247] 11. The method according to aspect 10, wherein the at least one functional element comprises at least one of the following elements: an actuator element, a sensor element, an energy source element, a display, a lens holder and at least one prefabricated additional optical element.

[0248] 12. A method according to clause 10 or 11, wherein the refractive index of at least one functional element deviates by no more than 3% from the refractive index of the starting material.

[0249] 13. The method according to at least one of clauses 10 to 12, wherein during the optical treatment, the starting material around the at least one functional element is irradiated from at least two sides with light of a first wavelength and light of a second wavelength.

[0250] 14. The method according to at least one of the preceding aspects, wherein the irradiation with light of the first wavelength and / or light of the second wavelength is performed using a plurality of light sources (5) such that the light irradiates at least partially overlapping layer partial volumes.

[0251] 15. An optical element produced according to the method of at least one of the preceding aspects.

Claims

1. A method for producing an optical element by processing an optically reactive material, comprising: - providing a starting material (3), which is optically reactive and fills the working volume (2); - optically treating the starting material (3) in the working volume (2) by irradiating light of a first wavelength and light of a second wavelength different from the first wavelength, wherein at least one material property of the starting material is changed by the optical treatment, and the optical treatment comprises the following steps: - irradiating a first layer partial volume of said working volume (2) filled with said starting material (3) with light of said first wavelength; - irradiating the first layer partial volume of the working volume (2) with light of the second wavelength, wherein the light of the second wavelength is in this case projected into the working volume (2); - irradiating a second partial volume of the working volume (2) filled with the starting material (3) with light of the first wavelength, the second partial volume being different from the first partial volume; - illuminating the second layer partial volume of the working volume (2) with light of the second wavelength, wherein the light of the second wavelength is in this case projected into the working volume (2); - repeating the above steps to perform layered optical treatment on the starting material (3) in the working volume (2) until the volume of the starting material (3) to be treated has been completely optically treated and the volume of the starting material (3) to be treated is completely or partially surrounded by the working volume (2), during which a green body is formed from the starting material (3); as well as - further processing the green compact such that the optical element is at least partially formed from the green compact, in particular completely formed from the green compact.

2. The method according to claim 1, wherein further processing of the green body comprises at least one of the following steps: - removing the green body from the starting material; - treating the green body with a solvent and / or a monomer; - drying the cleaned green body; and - subjecting the green body to a photochemical and / or thermal post-curing.

3. The method according to claim 2, wherein the solvent and / or monomers comprise a thermal initiator and / or an additional photoinitiator, which preferably reacts only at one wavelength.

4. The method according to at least one of the preceding claims, wherein the further processing of the green body comprises at least one of the following steps: - tempering the green body, - grinding the green body, - polishing the green body, and - coating the green body.

5. A method according to at least one of the preceding claims, wherein the light of the first wavelength and the light of the second wavelength are irradiated simultaneously and together into the first layer local volume or the second layer local volume at least during a temporal overlap, wherein preferably, the light of the first wavelength is irradiated along a first irradiation direction and the light of the second wavelength is irradiated onto the starting material (3) in the working volume (2) along a second irradiation direction extending perpendicularly to the first irradiation direction.

6. The method according to any of the preceding claims, wherein multicolor multiphoton polymerization is induced in the starting material (3) by optical treatment, resulting in a change in at least one material property of the starting material (3).

7. The method according to at least one of the preceding claims, wherein the starting material comprises a transparent organic polymer and / or an inorganic / organic polymer composite material, the starting material preferably being cured by optical treatment.

8. The method according to at least one of the preceding claims, wherein the viscosity of the starting material is 10 2 mPa s to 10 7 mPa s, and / or a yield strength of at least 0.1 Pa.

9. The method according to at least one of the preceding claims, wherein the forming of the optical element comprises the forming of at least one of the following optical elements: an optical lens, an imaging quality lens, an intraocular lens, a lens array, a diffuser, a prism, a grating, a diffractive optical element and an optical waveguide.

10. The method according to at least one of the preceding claims, wherein the starting material (3) comprises at least one functional element and at least a part of the optical element is formed adjacent to the at least one functional element.

11. The method according to claim 10, wherein at least one of the functional elements comprises at least one of the following elements: an actuator element, a sensor element, an energy source element, a display, a lens holder and at least one prefabricated additional optical element.

12. A method according to claim 10 or 11, wherein the refractive index of at least one of the functional elements deviates from the refractive index of the starting material by no more than 3%.

13. The method according to claim 10, wherein during the optical treatment, the starting material around at least one of the functional elements is irradiated from at least two sides with light of the first wavelength and light of the second wavelength.

14. The method according to claim 1, wherein the irradiation with light of the first wavelength and / or light of the second wavelength is performed using a plurality of light sources (5) such that the light irradiates at least partially overlapping layer partial volumes.

15. A method according to at least one of the preceding claims, wherein it is determined whether the first layer local volume or the second layer local volume is irradiated with the first wavelength, and based on the determination, a projection device (7) is driven, the projection device (7) being used to project light of the second wavelength into the working volume, thereby projecting the light of the second wavelength into the first layer local volume or the second layer local volume, in particular with a specific intensity distribution. 16 . The method according to claim 1 , wherein the light of the first wavelength and the light of the second wavelength are irradiated into the first layer partial volume or the second layer partial volume simultaneously and together, at least during a temporal overlap period.

17. A method according to at least one of the preceding claims, wherein the first layer local volume and the second layer local volume form adjacent layer local volumes of the starting material (3) in the working volume (2), wherein the first layer local volume and the second layer local volume are selected to be formed according to one of the following local volume configurations: overlapping at the edge, adjacent at the edge, and spaced from each other at the edge.

18. The method according to at least one of the preceding claims, wherein the light of the first wavelength is irradiated by a plurality of light generators to generate light segments, the plurality of light generators irradiating the working volume from different sides of a working container containing the working volume and generating the projected light segments by superposition of partial light beams.

19. The method according to at least one of the preceding claims, wherein the light of the first wavelength is irradiated by four light generators to generate light segments, wherein the four light generators are arranged in pairs opposite to each other, irradiate the working volume from different sides of a working container containing the working volume, and generate the projected light segments by superposition of partial light beams.

20. The method according to at least one of the preceding claims, wherein at least two light segments in different directions are created, in particular at least two light segments in different directions overlapping within the working volume.

21. The method according to at least one of the preceding claims, wherein, in order to form the light segment in the working volume, light of the first wavelength is irradiated into the working volume by means of a rotational movement.

22. The method according to at least one of the preceding claims, wherein the optical processing of the starting material (3) is observed with the aid of a light detector (8a; 8b), in particular a camera or a photodetector.

23. The method according to any of the preceding claims, wherein multicolor multiphoton polymerization is induced in the starting material (3) by optical treatment, resulting in a change in at least one material property of the starting material (3).

24. A method according to at least one of the preceding claims, wherein the light of the first wavelength is first irradiated in the first layer local volume and then in the second layer local volume, and the light of the first wavelength has a distribution that is basically uniform or non-uniform in terms of at least one of the following light parameters: light intensity and light color.

25. A method according to at least one of the preceding claims, wherein the light segment is formed within the working volume (2), in particular a light segment of light of the first wavelength is formed, and a focusing correction is continuously performed during the movement of the light segment in the working volume (2), in particular a focusing correction is continuously performed on the light of the second wavelength.

26. The method according to at least one of the preceding claims, wherein the starting material is subjected to at least one step for removing impurities, in particular particulate impurities, before irradiation, which step in particular comprises filtering the starting material by means of a filtering device.

27. A method according to at least one of the preceding claims, wherein further processing of the green body, in particular post-curing of the green body, is carried out under a protective gas environment, in particular an argon, carbon dioxide or nitrogen environment, so that the optical element is at least partially formed by the green body, in particular completely formed by the green body.

28. The method according to at least one of the preceding claims, wherein the further processing of the green body comprises photochemical post-curing of the green body by at least one additional photoinitiator, wherein the additional photoinitiator is configured to perform a photochemical reaction that initiates photochemical post-curing of the green body at a wavelength different from the first wavelength and the second wavelength.

29. The method according to claim 28, wherein the additional photoinitiator is an alpha-diketone, in particular camphorquinone, or comprises at least one alpha-diketone, in particular camphorquinone.

30. The method of claim 28 or 29, wherein the additional photoinitiator is irradiated at a wavelength between the first wavelength and the second wavelength.

31. The method according to claim 1, wherein the further processing of the green body comprises treating the green body with the solvent and / or monomer, in particular for washing the green body, wherein the molar mass of the solvent and / or monomer used is greater than or equal to 200 g / mol.

32. The method according to at least one of the preceding claims, wherein the further processing of the green body comprises treating the green body with the solvent and / or the monomer, in particular for washing the green body, wherein a highly volatile solvent and / or a highly volatile monomer is used.

33. The process according to claim 1, wherein the starting material used is free of inorganic and / or organic particles, in particular free of inorganic and / or organic particles having a diameter of more than 50 μm.

34. The process according to at least one of the preceding claims, wherein the starting materials used contain only organic components.

35. The process according to at least one of the preceding claims, wherein the starting materials used are free of organic polymers.

36. A method according to at least one of the preceding claims, wherein the optical element to be produced has a main extension plane with a planar geometry, wherein the construction direction of the optical element is selected to form an angle, in particular a right angle, to the main extension plane.

37. The method according to at least one of the preceding claims, wherein the first wavelength is less than or equal to 400 nm, in particular less than or equal to 375 nm, and / or the second wavelength is greater than 400 nm, preferably greater than 500 nm.

38. The method according to at least one of the preceding claims, wherein the starting material and / or the photoinitiator and / or the co-initiator do not contain amine bonds or the starting material and / or the photoinitiator and / or the co-initiator contain one or more amine bonds in an amount of not more than 10% by weight.

39. The method according to at least one of the preceding claims, wherein at least one first illumination device is used, which is configured to illuminate light of the first wavelength into the working volume (2) so as to generate at least one first light projection in the working volume, wherein the at least one first light projection comprises a plurality of light beams which pass through the working volume (2) in at least one light plane; and At least one light modulating device is used, which is associated with at least one of the first illumination devices, wherein at least one of the light modulating devices is configured to modulate the volume extension direction of two or more light beams among a plurality of light beams located in the at least one light plane so that the two or more light beams extend in a non-parallel arrangement relative to each other.

40. A method according to claim 39, wherein at least one of the light modulating devices comprises one or more optical elements, wherein each of the optical elements is configured to change an original volume extension direction of an incident light beam to generate a light beam having a volume extension direction different from the original volume extension direction.

41. The method according to claim 40, wherein the optical element is configured as an optical lens or comprises an optical lens, in particular a microlens, and / or an optical diffusing element, in particular an elliptical diffusing element.

42. The method according to at least one of the preceding claims, wherein at least one measure is performed for changing the optical properties of the green body, wherein The at least one measure preferably comprises changing the optical properties of the green body, thereby resulting in a reduction in the absorption properties of the green body at at least one wavelength in a wavelength range between 300 nm and 2000 nm, in particular between 350 nm and 900 nm, and / or resulting in an increase in the permeability properties of the green body at at least one wavelength in a wavelength range between 300 nm and 2000 nm, in particular between 350 nm and 900 nm, in particular between 400 nm and 800 nm.

43. The method according to claim 42, wherein the at least one measure comprises thermally treating the green body and / or optically treating the green body, in particular irradiating the green body with electromagnetic radiation, and / or chemically treating the green body.

44. An apparatus for processing an optically reactive material to produce an optical element, comprising: - a working volume (2) configured to receive a starting material (3) which is optically reactive and partially or completely fills the working volume (2); - an illumination device configured to provide light of a first wavelength and light of a second wavelength for irradiating a working volume (2) containing said starting material (3); and The illumination device is configured to perform the following optical treatment on the starting material (3) in the working volume (2): - irradiating a first layer partial volume of said working volume (2) filled with said starting material (3) with light of said first wavelength; - irradiating a first partial volume of said working volume (2) with light of said second wavelength, - irradiating a second partial volume of the working volume (2) with light of the first wavelength, the second partial volume being different from the first partial volume; - illuminating said second partial volume of said working volume (2) with light of said second wavelength; and - Repeat the above steps to perform layered optical processing on the starting material (3) in the working volume (2) until the volume of the starting material (3) to be processed has been completely optically processed and the volume of the starting material (3) to be processed is wholly or partially surrounded by the working volume (2).

45. The device according to claim 44, wherein the lighting device comprises at least one of the following elements: a Powell lens or a polygon mirror or a galvanometer mirror, and / or wherein the lighting device comprises: Laser or LED or thermal light source.

46. ​​An apparatus according to claim 44 or 45, wherein the illumination device is configured to allow layers further away from the light source of the second wavelength of light to be processed earlier in the course of time.

47. An optical element produced according to the method of at least one of the preceding claims.

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