Method for manufacturing at least one three-dimensional object by volume printing

Abstract

A method of fabricating at least one three-dimensional object by volumetric printing is disclosed.

Description

Technical Field

[0001] This invention relates to a method for manufacturing at least one three-dimensional object by volumetric printing. Background Technology

[0002] Methods for manufacturing three-dimensional objects through volumetric printing are widely known in the prior art. Such methods typically involve irradiating a photocurable resin within a working volume with light of at least one wavelength. Specifically, this type of volumetric printing technology involves irradiating a photocurable resin within a working volume with light of at least two different wavelengths.

[0003] While known volumetric printing methods generally facilitate the production of high-performance 3D objects, undesirable deformation effects are sometimes observed, such as bending or warping. These deformation effects can stem from various factors, including localized thermal stress within the 3D object, material shrinkage, or uneven reaction rates of the photocurable resin during the volumetric printing process. Furthermore, post-printing processes, such as those applied to the printed object, can also lead to undesirable deformation effects, such as deformation caused by uneven post-curing.

[0004] Therefore, there is a general need to improve various methods for manufacturing three-dimensional objects through volumetric printing, especially to find ways to overcome problems related to the corresponding deformation effects so that such improvements can produce three-dimensional objects with better performance, that is, in particular with less unnecessary deformation, thereby improving geometric accuracy.

[0005] Therefore, the object of the present invention is to provide an improved method for manufacturing three-dimensional objects by volumetric printing, which overcomes some of the shortcomings of existing methods for manufacturing three-dimensional objects by volumetric printing. Summary of the Invention

[0006] A first aspect of the invention relates to a method for manufacturing a three-dimensional object by volumetric printing. The three-dimensional object manufactured according to this method can be a technical component or a component of a technical component. In particular, the technical component can be an optical component, such as an optical lens or an array of optical lenses. Other examples of optical components include intraocular lenses, ophthalmic lenses, contact lenses, endoscopic lenses, microlenses, or optical implants (e.g., corneal implants). Therefore, this method can be a method for manufacturing a three-dimensional optical component, such as an optical lens or array of optical lenses, an intraocular lens, an ophthalmic lens, a contact lens, an endoscopic lens, a microlens, or an optical implant (e.g., a corneal implant). Furthermore, the invention contemplates other technical components and three-dimensional objects. Another exemplary technical component can be a mold or mold element, such as a mold half, a mold insert, etc., for forming at least one technical part. Therefore, this method can be a method for manufacturing a three-dimensional mold or mold element. The mold or mold element can define (e.g., by at least one forming profile) at least one cavity, wherein the at least one cavity at least partially represents the shape of at least one technical component to be formed by the mold or mold element. The corresponding technical components that can be formed using the mold or mold element can be optical components, such as optical lenses as described above.

[0007] Another aspect of the invention (which may be considered a separate aspect of the invention) may be a method of manufacturing at least one technical component using at least one mold or mold element, wherein the at least one mold or mold element is manufactured according to the first aspect of the invention, particularly by the volumetric printing process of step a) of the method according to the first aspect of the invention, such that all descriptions relating to step a) of the method according to the first aspect of the invention are applicable to this other aspect of the invention. Therefore, at least one mold or mold element manufactured according to the first aspect of the invention, particularly a mold or mold element manufactured by the volumetric printing process of step a) of the method according to the first aspect of the invention, can be used to manufacture at least one technical component, which may be, for example, an optical component, particularly an optical component as described above.

[0008] A method for manufacturing at least one technical component using at least one mold or mold element may be carried out in or by means of a forming apparatus. For example, the forming apparatus may be or include casting forming equipment or injection molding equipment.

[0009] A method for manufacturing at least one technical component using at least one mold or mold element may include at least one step of filling at least one mold or mold element with a plastic material. Specifically, the method may include the step of filling a cavity defined by at least one mold or mold element with a plastic material. The filling of the mold or mold element may be performed at least partially automatically by a filling device, particularly under the control of a hardware and / or software-implemented controller.

[0010] The corresponding plastic material can be or contains a curable material, particularly a photocurable or thermocurable material. Therefore, the method can include at least one step: irradiating the photocurable plastic material with electromagnetic radiation to cure the photocurable material, thereby forming at least one technical component; and / or at least one step: heating the thermocurable plastic material to cure the thermocurable material, thereby forming at least one technical assembly. The step of irradiating the curable material can be performed after the steps described above of filling the plastic material into a mold or mold element.

[0011] The malleable material may be filled into at least one mold or mold element, or into a cavity defined by at least one mold or mold element, at a temperature above room temperature. For example, the malleable material may be filled into at least one mold or mold element, or into a cavity defined by at least one mold or mold element, at at least 50°C, at least 60°C, at least 70°C, at least 80°C, at least 90°C, at least 100°C, at least 110°C, at least 120°C, at least 130°C, at least 140°C, at least 150°C, at least 160°C, at least 170°C, at least 180°C, at least 190°C, at least 200°C, or higher.

[0012] Alternatively or concurrently, at least one mold or mold element may be temperature-controlled by at least one temperature-regulating device assigned to it, i.e., in particular, for heating and / or cooling. The corresponding temperature-regulating device may include one or more temperature-regulating elements, respectively arranged outside and / or inside at least one mold or mold element. In particular, one or more temperature-regulating elements may be arranged near the wall defining the cavity, especially below that wall.

[0013] In either case, once the corresponding technical component is formed in at least one mold or mold element, the technical component can be removed from the at least one mold or mold element. Removal of the corresponding technical component from the at least one mold or mold element can be at least partially automated by a removal device, which may be or include a transfer device. For example, the transfer device may be or include a robot.

[0014] In either case, once the corresponding technical component is formed in at least one mold or mold element, the technical component can undergo at least one post-processing step. For example, the corresponding post-processing step may include: a post-curing process for at least one technical component; at least one coating step in which at least one surface of the technical component is coated with a coating, particularly a functional coating, such as an optical coating, a protective coating, an anti-stick coating, an adhesive coating, etc.; and at least one processing step in which at least one surface of the technical component is processed, for example, to achieve or maintain desired geometric tolerances.

[0015] In either case, the corresponding mold or mold element may undergo at least one post-processing step. For example, the corresponding post-processing step may include: at least one post-curing treatment of the mold or mold element; at least one coating step in which at least one surface of the mold or mold element is coated with a coating, particularly a functional coating, such as an optical coating, protective coating, anti-stick coating, adhesive coating, etc.; and at least one machining step in which at least one surface of the mold or mold element is machined, for example, to achieve or maintain desired geometric tolerances. In particular, the corresponding mold or mold element may be coated with a coating, such as an anti-stick coating, to facilitate the removal of parts formed using the mold or mold element.

[0016] The corresponding plastic material can be different from the material constituting the mold or mold element in order to avoid unnecessary chemical or physical interactions between the mold or mold element and the technical part it forms, especially interactions that may lead to unnecessary adhesion.

[0017] The corresponding moldable material can be a moldable polymer material or contain a moldable polymer material. The corresponding moldable polymer material can be a carbon-based polymer, such as a thermoplastic polymer or a thermosetting polymer. For example, the carbon-based polymer can be or contains an aliphatic polymer, which may contain one or more functional groups, such as one or more acrylate groups, carboxyl groups, carbonyl groups, epoxy groups, peptide groups, fluorinated groups, etc. Alternatively or additionally, the corresponding moldable polymer material can be or contains a silicone-based polymer. For example, the silicone-based polymer can be or contains a polysiloxane polymer.

[0018] In particular, when at least one technical component to be formed is or includes an optical component, the plastic material may be or includes a plastic material with high transparency, such as a transparency of more than 60%, especially more than 70%, and even more especially more than 80% in the visible light wavelength range.

[0019] Regardless of its specific chemical configuration, the corresponding plastic material can contain one or more functional additives to modify (especially enhance) one or more properties of the plastic material. Therefore, the plastic material can be considered as a matrix in which one or more functional additives are distributed. For example, the corresponding additives may include at least one additive capable of modifying / affecting at least one of the following properties of the plastic material: acoustic properties, tactile properties, optical properties, fluorescent properties, mechanical properties, rheological properties, electrical properties, thermal properties, magnetic properties, flame retardant properties, etc.

[0020] As an alternative to the method of manufacturing molds or mold elements, another aspect of the invention (which may be another independent aspect of the invention) may be a method of manufacturing molds using a technical component, wherein the technical component is manufactured according to the first aspect of the invention, particularly using the volumetric printing process of step a) of the method according to the first aspect of the invention, such that all descriptions relating to step a) of the method according to the first aspect of the invention are applicable to this other aspect of the invention. Therefore, at least one technical component manufactured according to the first aspect of the invention, particularly using the volumetric printing process of step a) of the method according to the first aspect of the invention, can be used to manufacture at least one mold or mold element. Thus, at least one technical component manufactured according to the first aspect of the invention, particularly the volumetric printing process of step a) of the method according to the first aspect of the invention, can be used as a positive mold for manufacturing molds or mold elements, and the resulting mold or mold element forms a negative mold of the corresponding technical component. Furthermore, the corresponding technical component may, for example, be or include optical elements as described above.

[0021] According to a first aspect of the invention, and particularly the volumetric printing process of step a) of the method according to the first aspect of the invention, the corresponding technical component manufactured can be used as a positive mold for manufacturing a mold or mold element, which may be provided with a functional coating, such as an anti-stick coating, which enables the mold or mold element (negative mold) forming the negative mold of the technical component to be easily removed from the technical component (positive mold), especially because there is no unnecessary interaction between the surface of the technical component (positive mold) and the mold or mold element (negative mold) formed thereon.

[0022] According to an exemplary embodiment of the above method, at least one technical component manufactured according to the first aspect of the invention, particularly a technical component manufactured using the volumetric printing process of step a) of the method according to the first aspect of the invention, can be at least partially embedded in a molding material for forming a mold or mold element. Embedding at least one technical component in the molding material may also include casting the molding material onto the at least one technical component and then curing the molding material to form a negative mold of the technical component.

[0023] The method of a first aspect of the invention includes a first step (step a) for performing a volumetric printing process to manufacture at least one three-dimensional object. Therefore, step a) includes a volumetric printing process in which at least one three-dimensional object is manufactured. The direct result of the volumetric printing process of step a) may be at least one green blank, which may require one or more post-processing steps (e.g., one or more post-curing steps) to be transformed into at least one brown object.

[0024] Therefore, step a) is typically performed using a volumetric printing device configured to perform a volumetric printing process to manufacture at least one three-dimensional object. The volumetric printing process is performed based on data containing geometric model information of the at least one three-dimensional object to be manufactured. For example, the corresponding data may be or contain CAD data or STL data. Therefore, the corresponding data may contain information describing the model surfaces (particularly triangulated surfaces) of the at least one three-dimensional object to be manufactured, for example, through at least one of unit normals, vectors, vertices, etc. Therefore, the corresponding data may be provided in CAD data format or STL data format. Of course, other data formats may also be considered.

[0025] Specifically, the data containing geometric model information of at least one three-dimensional object to be manufactured can be further processed by suitable data processing means (e.g., algorithms, software, etc.) to generate an image projection or image corresponding to the cross-sectional geometry of the three-dimensional object to be manufactured, or multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object to be manufactured. During the volumetric printing process in step a), the corresponding image projection or image can be radiated onto the working volume from one or more directions to cause the photocurable resin provided within the working volume to polymerize locally, thereby forming at least one three-dimensional object through volumetric printing.

[0026] Therefore, further processing of data containing geometric model information of at least one 3D object to be manufactured can directly generate an image corresponding to the cross-sectional geometry of the 3D object, or directly generate multiple points or lines corresponding to the cross-sectional geometry of the 3D object. In other words, an image corresponding to the cross-sectional geometry of the 3D object to be manufactured can be directly generated from the 3D model of the 3D object, or multiple points or lines corresponding to the cross-sectional geometry of the 3D object, and the 3D object can be directly manufactured based on these images, points, or lines corresponding to the cross-sectional geometry of the object. This is a particular advantage of volumetric printing processes that include multicolor photopolymerization (especially two-color photopolymerization), which other volumetric printing processes (especially those involving computational axial lithography) cannot achieve because these processes require different, and often more complex, data processing on the geometric model of the 3D object to be manufactured to obtain the information needed to initiate the volumetric printing process.

[0027] Furthermore, a geometric model of at least one three-dimensional object can be directly generated (especially reconstructed) from one or more images corresponding to the cross-sectional geometry of the three-dimensional object, or from multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object, using appropriate data processing methods (e.g., algorithms, software, etc.). Therefore, this method, particularly when it involves multicolor light aggregation (especially two-color light aggregation), typically includes a data processing step in which an image corresponding to the cross-sectional geometry of the three-dimensional object, or multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object, can be directly generated by processing the geometric model of at least one three-dimensional object. This data processing may include, for example, slicing the geometric model of at least one three-dimensional object into multiple slices with specific geometries (especially specific thicknesses) using slicing algorithms or slicing software.

[0028] Alternatively, the method, particularly when it involves multicolor light aggregation (especially two-color light aggregation), may typically include a data processing step (which can also be considered a reverse data processing step) in which a geometric model of at least one three-dimensional object can be directly generated by processing data from one or more images corresponding to the cross-sectional geometry of the three-dimensional object, or from multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object. For example, such data processing may include combining corresponding images, points, and lines corresponding to the cross-sectional geometry of the three-dimensional object to reconstruct a geometric model of at least one three-dimensional object using a geometric model reconstruction algorithm or geometric model reconstruction software.

[0029] Volumetric printing processes are performed based on or include multiple process parameters. As a non-limiting example, these process parameters (which may be or include irradiation parameters) may in particular relate to the polymerization of a photocurable resin within a working volume, which forms at least one three-dimensional object through local polymerization during volumetric printing. As another non-limiting example, these process parameters may relate to the movement of a movable device of the volumetric printing apparatus used to perform step a), for example, the movement of a container defining a corresponding working volume relative to an irradiation device (or vice versa), which is configured to emit light of at least one wavelength toward the corresponding working volume. Typically, one, several, or all of the process parameters in a volumetric printing process can cause undesirable deformation effects, such as bending effects, warping effects, etc., in the three-dimensional object to be printed or manufactured.

[0030] Typically, the wavelength range of the light used to irradiate the photocurable resin in at least one irradiation process can be: 350 nm to 500 nm, particularly 375 nm to 475 nm, more particularly 375 nm to 455 nm, and more particularly 395 nm to 425 nm.

[0031] In an exemplary embodiment of the method, the volumetric printing process of step a) may include at least one irradiation process, which may include: typically based on multiple irradiation parameters, irradiating a photocurable resin with light of a first wavelength and light of a second wavelength different from the first wavelength to form a three-dimensional object in at least one direction by multicolor photopolymerization (especially bicolor photopolymerization). The at least one direction may be the forming direction of the three-dimensional object to be printed, i.e., the direction in which the three-dimensional object is printed. This method is generally capable of volumetric printing one or more three-dimensional objects in at least one (forming) direction.

[0032] In this exemplary embodiment of the method, at least one irradiation process includes irradiating the photocurable resin with light of a first wavelength and light of a second wavelength different from the first wavelength. The first wavelength may include wavelengths ranging from 350 nm to 500 nm, particularly 375 nm to 450 nm, more particularly 385 nm to 440 nm, more particularly 395 nm to 420 nm, and more particularly 400 nm to 410 nm. The first wavelength may comprise a wavelength spectrum, particularly one that at least partially covers the aforementioned corresponding ranges. For example, the first wavelength may be approximately 375 nm. Typically, the selection of the first wavelength should at least consider the photochemical properties of the photoinitiator molecules of at least one photoinitiator in the photocurable resin, particularly its photochromic properties. The second wavelength may include wavelengths ranging from 400 nm to 1000 nm, particularly 425 nm to 750 nm, more particularly 450 nm to 675 nm, and more particularly 500 nm to 650 nm. The second wavelength may comprise a wavelength spectrum, particularly one that at least partially covers the aforementioned corresponding ranges. For example, the second wavelength may be approximately 475 nm. Preferably, the second wavelength of light can encompass a wavelength range excluding the first wavelength. Typically, the selection of the second wavelength takes into account at least the photochemical properties of the photoinitiator molecules of at least one photoinitiator in the photocurable resin, particularly its photochromic properties.

[0033] The photocurable resin can be irradiated with a first wavelength of light and a second wavelength of light, such that the first wavelength and the second wavelength of light intersect in the forming region. The forming region typically refers to the area where the photocurable resin undergoes photopolymerization, during which polymerization-based photocuring and / or curing occurs, forming at least one cross-section of the three-dimensional object to be printed. Specifically, the first wavelength of light can irradiate the working volume and the photocurable resin at a different angle and / or a different direction relative to the second wavelength of light. For example, the first wavelength of light can irradiate the photocurable resin at an angle of approximately 90° relative to the second wavelength of light.

[0034] The first wavelength of light may comprise a light sheet, which may consist of multiple beams passing through the working volume and the photocurable resin, respectively. These beams may include two or more (substantially) parallel beams. For example, the individual beams may form a light plane. The light plane may be or comprise a light plane in which one or more beams (e.g., (substantially) parallel beams) extend adjacently such that there is no gap between directly adjacent beams. Notably, at least some directly adjacent beams may also partially overlap. Alternatively, the light plane may be or comprise a light plane in which one or more beams extend adjacently such that there is a gap between directly adjacent beams. The individual beams may be generated by a directional light emitting device (e.g., a laser device), which may form part of the irradiation apparatus of the volumetric printing device used to implement the method.

[0035] Each light sheet or beam may include a principal extension direction, which can generally be understood as the direction of extension of the light sheet or beam between opposing wall segments or wall surfaces of the container defining the working volume. Specifically, the principal extension direction of each light sheet or beam can be understood as the primary propagation direction of the light sheet or beam between opposing wall segments or wall surfaces of the container defining the working volume. Therefore, the principal extension direction of each light sheet or beam may correspond to a direction along a line that substantially halves the divergence or divergence angle of the light sheet or beam within the working volume or photocurable resin.

[0036] The height direction or height extension of a light sheet or beam can generally be understood as the direction that extends the most in space and is perpendicular to the main extension direction. In particular, the height direction or height extension can be the direction or extension parallel to the wall or wall segment of the container that defines the working volume, through which the light sheet or beam enters the working volume.

[0037] The second wavelength of light can include an image projection corresponding to the cross-sectional geometry of the three-dimensional object to be printed, or it can include multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object to be printed. These points or lines can form a pattern, such as a fill pattern. The corresponding projection can be generated by a light projection device (e.g., a digital light projection device), which can be part of the irradiation device of the volumetric printing apparatus for implementing the method. The corresponding points or lines can be generated by a directional light emitting device (e.g., a laser device), which can be part of the irradiation device of the volumetric printing apparatus for implementing the method.

[0038] At least one irradiation process may include irradiating a photocurable resin with light from at least two different (spatial) directions, particularly causing one or more volumetric units of the photocurable resin to be irradiated with light from at least two different angles. Thus, at least one irradiation process may include irradiating the photocurable resin from a first direction and at least one second direction different from the first direction. The first direction may be or include a direction perpendicular to the forming direction of the three-dimensional object to be printed, and the second direction may be a direction parallel to the forming direction of the three-dimensional object to be printed. Therefore, a corresponding first direction may be associated with a corresponding first angle, and a corresponding second direction may be associated with a corresponding second angle, for example, the second angle may be 90° relative to the first angle. In any case, light from the corresponding first direction may intersect with light from the corresponding second direction within the forming region. As described above, the forming region is typically the region where the photocurable resin undergoes photopolymerization, photocuring, and / or curing, forming at least one cross-section of the three-dimensional object to be printed.

[0039] During at least one irradiation process, at least one of the following can be moved: the photocurable resin, the irradiation device emitting light of at least one wavelength, and the forming region within the photocurable resin irradiated by light of at least one wavelength during at least one irradiation process. Movement of the photocurable resin, the irradiation device emitting light of at least one wavelength, or the forming region within the photocurable resin irradiated by light of at least one wavelength during at least one irradiation process enables an efficient printing process and high printing speed. Therefore, the method may particularly include: the forming region can be moved along at least one direction, particularly relative to a corresponding container containing the photocurable resin (as described above). This at least one direction can include the forming direction of the three-dimensional object to be printed. For example, the movement of the at least one forming region can, for example, be relative to at least one functional component of a volumetric printing apparatus for carrying out the method. The corresponding functional component of the volumetric printing apparatus can be a corresponding container or the irradiation device. Thus, during at least one irradiation process, at least one forming region can be actively moved (e.g., by coupling with a drive device (e.g., a motor)) along at least one direction (particularly the forming direction), for example at a nominal speed, through at least a portion of the container volume, while the container remains stationary. Alternatively, during at least one irradiation process, the container can be actively moved (e.g., by coupling with a drive device (e.g., a motor)) along at least one direction (particularly the forming direction), while at least one forming area remains stationary. Furthermore, both at least one forming area and the container can be actively moved, for example by coupling with a drive device (e.g., a motor), wherein at least one forming area and the container can move in the same or opposite directions. Additionally, the nominal speed and / or direction of movement of at least one forming area and / or container along at least one direction (particularly relative to the container) can be varied. Additionally or alternatively, the second irradiation unit of the two-color irradiation apparatus can be actively moved along at least one direction (particularly the forming direction), while the container or at least one forming area can be actively moved or not actively moved. Actively moving the second irradiation unit of the two-color irradiation apparatus can be used to achieve focus correction of the second wavelength of light. Therefore, embodiments are also contemplated in which the second irradiation unit of the two-color irradiation apparatus, at least one forming area, and the container are actively moved before, during, or after at least one irradiation process. The corresponding active movement can be controlled by a controller of the device used to implement the volumetric printing process.

[0040] The various process parameters used to implement the corresponding volumetric printing process can typically be or include parameters of at least one irradiation process. These parameters can affect the spatial and / or temporal irradiation of the photocurable resin with a first wavelength of light and / or a second wavelength of light, thereby affecting the spatial and / or temporal polymerization of the photocurable resin within the working volume. The corresponding process parameters may also additionally or alternatively be or include the number of irradiation steps in which one or more volume elements (e.g., voxels) of the photocurable resin are irradiated with a first wavelength of light and / or a second wavelength of light. Therefore, the corresponding printing parameters can be or include control parameters of the volumetric printing apparatus used to implement the method. These control parameters can relate to the spatial and / or temporal irradiation of the photocurable resin with a first wavelength of light and / or a second wavelength of light to form at least one three-dimensional object in at least one direction, particularly by multicolor photopolymerization, and more particularly by two-color photopolymerization. Specifically, the corresponding process parameters can be or include control parameters of the irradiation apparatus of the corresponding volumetric printing apparatus, which is configured to irradiate the photocurable resin with a first wavelength of light and a second wavelength of light, respectively, to form at least one three-dimensional object in at least one direction by multicolor photopolymerization (particularly two-color photopolymerization). The corresponding process parameters may also be or include control parameters of the drive unit of the corresponding volumetric printing equipment, which is configured, for example, to move the photocurable resin or the container holding the photocurable resin in at least one direction.

[0041] In one exemplary embodiment of this method, the volumetric printing process can implement the principle of a volumetric printing method called "two-color voxel lithography." The basic principle of two-color voxel lithography is described in detail in WO2020 / 245456A1, the contents of which are incorporated herein by reference.

[0042] The method includes a second step (step b) for determining at least one attribute of at least one three-dimensional object printed in step a) and generating determination information indicating the at least one determined attribute. Therefore, step b) is typically performed by a determining device that may include one or more determining elements (e.g., sensors) configured to determine at least one attribute of the at least one three-dimensional object printed in step a) and generate determination information indicating the at least one determined attribute. The corresponding determination information may include raw data (e.g., data further processed or processable by a controller). In either case, the corresponding determination information can directly or indirectly indicate at least one (determined) attribute of the at least one three-dimensional object printed during the volumetric printing process in step a).

[0043] Typically, the corresponding properties of the three-dimensional object that can be determined in step b) may include at least one chemical property and / or at least one physical property of the three-dimensional object. Some non-limiting examples of chemical and / or physical properties are provided below.

[0044] The method includes a third step (step c) for comparing at least one determined attribute of at least one three-dimensional object with at least one reference attribute of a reference three-dimensional object, and generating comparison information indicating the comparison result. The reference three-dimensional object is, in particular, a predefined or predefined nominal three-dimensional object or target three-dimensional object, and the at least one reference attribute is, in particular, a predefined or predefined nominal attribute or target attribute. It is noteworthy that the reference three-dimensional object can be a real three-dimensional reference object or a digital representation of a three-dimensional reference object, such as a three-dimensional reference object model of the three-dimensional object to be manufactured, particularly a CAD model or STL model. Step c) is typically performed by a comparison device, which can be a hardware and / or software implementation, and is therefore typically a computer-implemented comparison device. The comparison device is configured to compare at least one determined attribute of at least one three-dimensional object with at least one reference attribute and generate comparison information indicating the comparison result. The comparison device may include a data storage device or may communicate with a data storage device. The data storage device may, for example, be a data server storing one or more reference attributes, such as corresponding predefined or predefined nominal attributes or target attributes of one or more predefined or predefined nominal or predefined three-dimensional objects or target three-dimensional objects. The comparison device may include one or more algorithms that are suitable for comparing at least one determined attribute of at least one three-dimensional object with at least one corresponding reference attribute and generating comparison information indicating the comparison result.

[0045] It is worth noting that the corresponding reference attributes (e.g., corresponding predefined or predefined nominal or target attributes), especially with respect to the intended application and / or function of the at least one 3D object to be manufactured, can serve as desired or necessary attributes of the at least one 3D object to be manufactured. Similarly, the corresponding reference 3D object (e.g., corresponding predefined or predefined nominal or target 3D object), especially with respect to the intended application and / or function of the at least one 3D object to be manufactured, can serve as desired or necessary 3D objects. Therefore, the corresponding predefined or predefined nominal or target attributes can correspond to desired or necessary attributes of the at least one 3D object to be manufactured, and the predefined or predefined nominal or target 3D object can correspond to desired or necessary 3D objects to be manufactured.

[0046] The method includes a fourth step (step d) for determining whether a comparison result indicates that the deviation (if any) between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold. Step d) can also be performed using a suitable comparison device, which may include or communicate with a data storage device, which may be or include a data server storing the relevant threshold. The comparison device may include one or more algorithms for determining whether a comparison result indicates that the deviation (if any) between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold.

[0047] For example, a deviation of at least 0.1%, particularly at least 1%, more particularly at least 5%, more particularly at least 10%, more particularly at least 15%, and more particularly at least 20% from a determined attribute to an associated predefined or predefined nominal or target attribute can be considered a corresponding deviation, thereby triggering a change to at least one of the following: at least one parameter of the geometric model of the 3D object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process. However, the corresponding threshold typically depends at least on the specific attribute and the specific 3D object, and therefore usually needs to be set individually for each specific attribute and each specific 3D object (or at least a specific type of specific object), for example, based on experimental results, computer simulations, etc.

[0048] If the comparison results indicate that the deviation between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold, the method may include changing at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process. Therefore, the method is capable of determining the deviation between one or more determined attributes of the at least one three-dimensional object printed in step a) and corresponding one or more reference attributes (e.g., predefined or predefined nominal or target attributes). If these deviations are considered significant, i.e., the deviation exceeds at least one corresponding threshold, the method is capable of actively and intentionally changing at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process, in order to at least partially reduce or even completely compensate for the determined deviations, for example, in one or more subsequent volumetric printing processes. Therefore, the step of changing at least one of the following aims to reduce or completely compensate for the determined deviations: at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process. The steps of changing at least one of the following: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process, and therefore particularly include changing at least one of the following: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process, such changes are capable of reducing or fully compensating for determined deviations when repeating one, several, or all of the steps of the method.

[0049] Therefore, the step of altering at least one of the following: a geometric model of at least one three-dimensional object to be manufactured; a process parameter of at least one volumetric printing process; or a process parameter of at least one post-processing process; may include performing operations previously taken in the associated volumetric printing process and / or post-processing process that have successfully altered one or more specific properties of the three-dimensional object by intentionally changing at least one of the following: at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured; at least one process parameter of the volumetric printing process; or at least one process parameter of the post-processing process. For example, one or more process parameters of the current or upcoming volumetric printing process may be altered, for example, by changing one or more irradiation parameters that have had a positive effect on one or more properties of the printed three-dimensional object in a previous volumetric printing process. To give a more specific example, previous experimental results, simulations, etc., may have shown that irradiation parameters associated with the polymerization of a particular photocurable resin, such as irradiation intensity, irradiation time, irradiation rate, etc., can reduce undesirable deformation effects of the printed three-dimensional object, such as deformation caused by bending, warping, etc. Therefore, altering these corresponding irradiation parameters, for example by increasing or decreasing one or more of them, can reduce undesirable deformation effects of at least one three-dimensional object.

[0050] Similar methods are also applicable to other process parameters in volumetric printing. Furthermore, similar methods are also applicable to changing at least one of the following: at least one parameter of the geometric model of the 3D object to be manufactured, and at least one process parameter of the post-processing, such as parameters related to the post-curing of the 3D object, such as post-curing strength, post-curing time, post-curing speed, etc.

[0051] If the comparison results indicate that the deviation between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold, the method includes not only changing at least one of the following: at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, at least one process parameter of the post-processing process, but also repeating steps a)–d) using at least one modified parameter of the geometric model of the at least one three-dimensional object to be manufactured and / or at least one modified process parameter of the volumetric printing process and / or at least one modified process parameter of the post-processing process until the comparison results indicate that, for at least one other three-dimensional object, the deviation between at least one determined attribute of that other three-dimensional object and at least one reference attribute does not exceed the threshold.

[0052] Therefore, the method may include a fifth step (step e) which includes: if the comparison result indicates that the deviation between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold, then changing at least one of the following: at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, at least one process parameter of the post-processing process, and repeating steps a)-d) once or more using at least one modified parameter of the geometric model of the at least one three-dimensional object to be manufactured and / or at least one modified process parameter of the volumetric printing process and / or at least one modified process parameter of the post-processing process, until the comparison result indicates that the deviation between the determined attribute of the three-dimensional object or another three-dimensional object and at least one reference attribute no longer exceeds at least one threshold.

[0053] The above-described method steps enable improvements in the manufacture of 3D objects via volumetric printing because, at least in steps b) and c), the method includes inherent control over one or more properties of the current 3D object manufactured in step a), conforming to one or more desired or required predefined or predefined nominal or target properties. Furthermore, the method includes an active step in step e) that modifies at least one of the following: at least one parameter of the geometry of the at least one 3D object to be manufactured, at least one process parameter of the volumetric printing process, at least one process parameter of the post-processing process, and prints at least one other 3D object based on the corresponding modified parameters; this other 3D object typically possesses improved properties, particularly less unwanted deformation, especially relative to the current (or previous) 3D object. Therefore, the optimization process for manufacturing 3D objects via volumetric printing, particularly an iterative optimization process, can be implemented in one or more stages, each stage typically including the execution of steps a)–e) as described above.

[0054] It is worth noting that one, several, or all steps of the method, for example by a controller of the system used to implement the method (e.g., the system of the second aspect of the invention), can be implemented at least semi-automatically, and in particular, fully automatically. Specifically, each change to at least one of the following: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process, can be implemented at least semi-automatically, and in particular, fully automatically. Therefore, the method can optimize the manufacture of at least one three-dimensional object by volumetric printing at least semi-automatically, and in particular, fully automatically.

[0055] Other exemplary embodiments of the method will be described in detail below. It is worth noting that each of these exemplary embodiments can be arbitrarily combined with at least one other exemplary embodiment.

[0056] As described above, the steps of determining at least one property of at least one three-dimensional object and generating determination information indicating at least one determined property of at least one three-dimensional object may include determining at least one chemical property and / or physical property of at least one three-dimensional object.

[0057] In an exemplary embodiment of the method, at least one chemical property may be or include at least one of the following: the chemical composition of at least one three-dimensional object printed in step a); the chemical reaction state of at least one three-dimensional object printed in step a), particularly the polymerization state of at least one three-dimensional object printed in step a). The corresponding chemical property of at least one three-dimensional object can be determined by a determining device, which may be or include at least one of the following: a spectroscopic device, such as a device for performing spectroscopic analysis, particularly a device for performing ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, or Raman spectroscopy, or a device for performing differential scanning calorimetry.

[0058] In an exemplary embodiment of the method, at least one physical property may be or include at least one of the following: acoustic properties, optical properties, geometric properties, mechanical properties, surface properties, electrical properties, thermal properties, or magnetic properties of at least one three-dimensional object printed in step a). The corresponding physical property of at least one three-dimensional object can be determined by a determining device, which may be or include at least one of the following: an interferometer, an impedance meter, an optical sensor (e.g., a camera or a one-dimensional or multi-dimensional scanner), a microscope, a conductivity or resistance meter, a thermal conductivity or thermal resistance meter, a testing machine (e.g., for conducting tests under mechanical loads, such as bending tests, compressive strength tests, tensile strength tests, flexural strength tests, shear strength tests, torsion tests, hardness tests), a roughness meter (profilometer), a magnetometer, etc. In addition, a testing device may be used, which is configured to perform a test on at least one function of at least one three-dimensional object for the intended application and / or function of at least one three-dimensional object. For example, a testing device for testing whether at least one function of the at least one three-dimensional object, such as optical function, geometric function, mechanical function, surface function, electrical function, thermal function, magnetic function, etc., meets the intended application and / or function of the object, is used to determine whether the at least one three-dimensional object printed in step a) meets the function expected or required by the intended application and / or function of the at least one three-dimensional object.

[0059] In another exemplary embodiment of the method, at least one determined attribute of at least one three-dimensional object can indicate deformation of at least one three-dimensional object, particularly deformation caused by bending, warping, etc., of at least one three-dimensional object, and more particularly, deformation caused by bending, warping, etc., resulting from the process of at least one three-dimensional object during volume printing and / or post-processing. Any deformation of at least one three-dimensional object may cause at least one attribute of at least one three-dimensional object (e.g., but not limited to geometric attributes) to deviate relative to a reference attribute of a reference three-dimensional object. Therefore, the determining device may include one or more algorithms adapted to derive the deviation related to the reference attribute of the reference three-dimensional object from the determined attributes of at least one printed three-dimensional object, for example, through methods such as data correlation principles, artificial intelligence principles, machine learning principles, etc. However, it is also conceivable, particularly in a measurement-based manner, to determine the corresponding deviation by comparing the determined attributes of at least one three-dimensional object with the relevant reference attributes of the reference three-dimensional object (particularly based on measurement). Therefore, any determination of the attributes of a three-dimensional object mentioned herein may also generally include the measurement of the corresponding attribute of the three-dimensional object.

[0060] As described above, at least one property of at least one three-dimensional object can also be determined by a measuring device configured to measure at least one chemical and / or physical property of at least one three-dimensional object. Non-limiting examples of such measuring devices include at least one of the determining devices described above. Therefore, any of the determining devices described above can also be a measuring device or include a measuring device, and vice versa.

[0061] In other exemplary embodiments of the method, changing at least one parameter of the geometric model of at least one 3D object to be manufactured may include changing the CAD file, particularly the STL file, representing the model of the at least one 3D object to be manufactured. Thus, within the framework of this method, particularly in step e), a revised CAD or STL file can be generated, wherein each revision of the CAD or STL file is designed to reduce undesirable deformation effects, thereby positively impacting the properties (e.g., geometric accuracy) of at least one further printed 3D object. Changing the information in the CAD or STL file regarding or representing the model of the at least one 3D object to be manufactured may particularly include repositioning and / or reorienting one or more vertices, for example, changing the vertex density locally or globally. Of course, one or more other image parameters of the corresponding CAD or STL file may also be changed accordingly. Typically, at least one image parameter of the model of the at least one 3D object to be manufactured may be changed, particularly pixels, voxels, or vertices. Therefore, the information in the CAD file (particularly the STL file) regarding or representing the model of the at least one 3D object to be manufactured may be or include the pixels, voxels, vectors, or vertices of that model. The experiments unexpectedly showed that, for example, by repositioning and / or reorienting one or more pixels, voxels, vectors, or vertices, and accordingly changing the image parameters, it is possible to have a positive effect on reducing unwanted deformation effects on one or more further printed 3D objects, thereby improving the geometric accuracy of printed 3D objects.

[0062] As described above, data containing geometric model information of at least one three-dimensional object to be manufactured, such as CAD files or models, STL files or models, can be further processed by suitable data processing means (e.g., algorithms, software, etc.) to generate projections or images of one or more cross-sectional geometries of the at least one three-dimensional object to be manufactured. As described above, during the volumetric printing process in step a), the corresponding projection image or image can be projected onto the working volume from one or more directions to cause the photocurable resin provided within the working volume to undergo a polymerization reaction. The photocurable resin is locally polymerized, thereby forming at least one three-dimensional object through volumetric printing.

[0063] The inventors unexpectedly discovered that directly changing at least one parameter in the geometric model of at least one three-dimensional object to be manufactured is more advantageous than processing projections or images of one or more cross-sectional geometries of the at least one three-dimensional object to be manufactured, obtained from a corresponding model of the object, for the following reasons. For example, directly changing at least one parameter in the geometric model of at least one three-dimensional object to be manufactured improves the accuracy of parameter changes because the original data can be directly modified without altering any data generated by further processing the original data (e.g., corresponding projections or images). Furthermore, changing at least one parameter in the geometric model of at least one three-dimensional object to be manufactured requires fewer computational resources compared to further processing of the corresponding projections or images. Thus, the efficiency of changing at least one parameter in the geometric model of at least one three-dimensional object to be manufactured can also be improved, for example, because directly changing at least one parameter in the geometric model of at least one three-dimensional object to be manufactured may require fewer and / or simpler computational steps.

[0064] This is particularly applicable to the method, especially when the method involves multicolor light polymerization, particularly two-color light polymerization. As mentioned above, the method may include a data processing step in which an image corresponding to the cross-sectional geometry of the three-dimensional object, or multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object, can be directly generated by data processing of the geometric model of at least one three-dimensional object. In addition, or alternatively, the method may also include another data processing step (which can also be regarded as a reverse data processing step) in which a geometric model of at least one three-dimensional object can be directly generated by data processing of one or more images corresponding to the cross-sectional geometry of the three-dimensional object, or multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object.

[0065] As described above, the first data processing step may include, for example, slicing the geometric model of at least one 3D object into multiple slices with specific geometries (especially specific thicknesses) using a slicing algorithm or slicing software; the second data processing step may include, for example, combining corresponding images, points, and lines corresponding to the cross-sectional geometry of the 3D object using a geometric model reconstruction algorithm or geometric model reconstruction software to reconstruct the geometric model of at least one 3D object. Both the first and second data processing steps are efficient to implement. For example, in the first data processing step, the corresponding slices can be obtained directly from the geometric model of the 3D object to be manufactured, and in the second data processing step, the corresponding geometric model of the 3D object can be obtained directly from the corresponding slices of the 3D object. These two data processing steps also allow any modifications to the geometric model of the 3D object (e.g., CAD files or models, or STL files or models) to be effectively modified in relatively few steps, especially compared to volumetric printing processes involving computational axial lithography (CAL) or similar volumetric printing processes.

[0066] Specifically, this is particularly applicable when the method involves multicolor photopolymerization, especially two-color photopolymerization. As mentioned above, the method may include a direct data processing step in which, by processing the geometric model of at least one three-dimensional object (especially slicing the geometric model), an image corresponding to the cross-sectional geometry of the three-dimensional object, or multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object, can be directly generated. The directly generated image, especially after further data processing (e.g., using one or more grayscale algorithms), can preferably be used to manufacture at least one three-dimensional object without substantially altering the shape of the image contour or the corresponding cross-sectional geometry of the object specified by the image. This direct data processing step also allows the geometric model of any three-dimensional object (e.g., a CAD file or model, or an STL file or model) to be efficiently modified in relatively few steps to obtain a new target geometric model of the three-dimensional object. This method is particularly advantageous compared to volumetric printing processes that include iterative or indirect data processing steps, especially when the volumetric printing process includes computational axial lithography (CAL) or similar volumetric printing processes. In a volumetric printing process that includes iterative or indirect data processing steps, an image for manufacturing at least one three-dimensional object is obtained by iteratively repeating the following steps: a) processing the image to generate a superimposed geometric model; b) comparing the superimposed geometric model with a target geometric model; c) modifying the image; and repeating this process until the superimposed geometric model is substantially identical to the target geometric model.

[0067] It is worth noting that changes to information in the CAD file (especially the STL file) regarding or representing the model of at least one three-dimensional object to be manufactured can be implemented in a manner that is at least semi-automatic, preferably fully automatic, based on an algorithm applicable to changing the information in the CAD file (especially the STL file) regarding or representing the model of the three-dimensional object to be manufactured according to at least one target criterion. The corresponding target criterion may be or include one or more target attributes of the three-dimensional object to be printed. The corresponding target attributes may include the chemical and / or physical properties of the at least one three-dimensional object to be printed. As mentioned above, chemical properties may include at least one of the following: the chemical composition of the at least one three-dimensional object printed in step a); the chemical reaction state of the at least one three-dimensional object printed in step a), particularly including the polymerization state of the at least one three-dimensional object printed in step a). As mentioned above, physical properties may include at least one of the acoustic, optical, geometric, mechanical, surface, electrical, thermal, or magnetic properties of the at least one three-dimensional object printed in step a). As a non-limiting example, the corresponding algorithm could be or incorporate linear regression principles to reduce undesirable deformation effects, thereby (particularly through iteration) improving the properties of at least one 3D object to be printed, especially increasing the fidelity of the at least one 3D object to be printed. However, other computational models and principles such as artificial intelligence and machine learning can also be considered.

[0068] In other exemplary embodiments of the method, changing at least one process parameter of the volumetric printing process may include changing at least one parameter of the irradiation process of the volumetric printing process, which, as described above, includes irradiating a photocurable resin within a working volume with light of at least one wavelength. The corresponding process parameter may be or include at least one of the following: the duration of irradiation of the photocurable resin with light of at least one wavelength, the start time of irradiation of the photocurable resin with light of at least one wavelength, the end time of irradiation of the photocurable resin with light of at least one wavelength, the intensity of the light used to irradiate the photocurable resin, the wavelength of the light used to irradiate the photocurable resin, the printing speed, the movement path of the working volume during the irradiation process, the printing direction, the orientation of the three-dimensional object within the working volume (particularly the orientation of the principal axis or axis of symmetry of the three-dimensional object); and so on. Experimental results show that changing at least one of the above-mentioned irradiation process parameters can significantly reduce the deformation effect of one or more subsequently printed three-dimensional objects, thereby (particularly through iteration) improving the performance of at least one three-dimensional object to be printed, particularly increasing the fidelity of the three-dimensional object to be printed.

[0069] For example, it was surprisingly observed that changing the orientation of a 3D object within the working volume, particularly changing the orientation of its principal axes or axes of symmetry, could reduce undesirable deformation effects. This is believed to be because, at each location of the corresponding light sheet, the area illuminated by the second wavelength of light is minimized.

[0070] In other exemplary embodiments of the method, changing at least one process parameter of the volumetric printing process may include changing at least one parameter of the photocurable resin used for volumetric printing of three-dimensional objects. Furthermore, the corresponding parameter of the photocurable resin may be or include chemical parameters of the photocurable resin, such as the chemical composition of the photocurable resin, the concentration and / or type of photoinitiator in the photocurable resin, and / or physical parameters of the photocurable resin, such as the density, temperature, absorptivity and / or transmittance of light for at least one wavelength, viscosity, etc. Experimental results show that changing at least one of the above-mentioned parameters of the photocurable resin can significantly reduce the deformation effect of one or more subsequently printed three-dimensional objects, thereby improving the performance of at least one three-dimensional object to be printed (particularly through iteration), and particularly improving the fidelity of at least one three-dimensional object to be printed.

[0071] In other exemplary embodiments of the method, at least one parameter of the transfer of at least one three-dimensional object via a transfer device, such as a transfer robot for transferring a three-dimensional object from a volumetric printing device to a post-processing device, can be changed. The corresponding transfer parameter of the at least one three-dimensional object may be or includes changing at least one of the following: the gripping position of the at least one three-dimensional object for transfer (at which the at least one three-dimensional object is gripped, for example, by a gripping device), the transfer path for transferring the at least one three-dimensional object, the transfer speed (and the relevant forces acting on the at least one three-dimensional object during transfer), etc. Experimental results show that changing the above at least one transfer parameter can significantly reduce the deformation effect of one or more subsequently printed three-dimensional objects, thereby enabling (particularly through iteration) improvement of the performance of the at least one three-dimensional object to be printed, especially improving the fidelity of the at least one three-dimensional object to be printed.

[0072] In other exemplary embodiments of the method, changing at least one process parameter of the post-processing (which may typically be or include a post-curing process) may include changing at least one of the following: the duration of the post-processing; the start time of the post-processing; the end time of the post-processing; the energy, intensity, or wavelength of the post-processing, particularly the energy, intensity, or wavelength of radiation applied to at least one three-dimensional object during the post-processing; the temperature or temperature profile of the post-processing; the speed of the post-processing; and at least one parameter of at least one process gas (e.g., an inert gas) during the post-processing, such as chemical parameters (e.g., chemical composition, concentration, etc.), physical parameters, flow parameters, concentration parameters, etc. In particular, the corresponding temperature or temperature profile associated with the sintering process (which is an example of the corresponding post-processing) may be changed. The corresponding temperature profile may include at least one of the following: a positive temperature ramp (heating ramp), a negative temperature ramp (cooling ramp), or a temperature plateau. The corresponding positive or negative temperature ramp may be a linear ramp or a non-linear ramp.

[0073] Experimental results show that changing at least one of the above parameters in the post-processing can unexpectedly and significantly reduce the deformation effect of one or more subsequently printed 3D objects, thereby improving the performance of at least one 3D object to be printed (especially through iteration), particularly improving the fidelity of at least one 3D object to be printed.

[0074] In other exemplary embodiments of the method, at least step c) can be performed by a controller, particularly by at least one algorithm of the controller, which is configured to compare at least one determined attribute of the 3D object with at least one reference attribute (particularly a target attribute) of a reference 3D object (particularly a target 3D object), and generate comparison information indicating the comparison result. Similarly, steps d) and e) (at least in terms of determining whether a threshold is exceeded) can also be performed by the controller, particularly by at least one algorithm of the controller, which is configured to determine whether the comparison result indicates that the deviation between at least one determined attribute of the 3D object and at least one reference attribute of the reference 3D object exceeds the threshold. If the comparison result indicates that the deviation between at least one determined attribute of the 3D object and at least one reference attribute of the reference 3D object exceeds the threshold, the control changes at least one of the following: at least one parameter of the geometric model of the 3D object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process.

[0075] Specifically, the corresponding controller may include one or more algorithms adapted to modify at least one of the following according to at least one target criterion: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process. The corresponding target criterion may be or include one or more target properties of the at least one three-dimensional object to be printed. The corresponding target properties may include the chemical and / or physical properties of the three-dimensional object to be printed. As mentioned above, the chemical properties may include at least one of the following: the chemical composition of the at least one three-dimensional object printed in step a); the chemical reaction state of the at least one three-dimensional object printed in step a), particularly the polymerization state of the at least one three-dimensional object printed in step a). As mentioned above, the physical properties may include at least one of the following characteristics of the at least one three-dimensional object printed in step a): acoustic properties, optical properties, geometric properties, mechanical properties, surface properties, electrical properties, thermal properties, or magnetic properties.

[0076] As described above, at least one irradiation process in the volumetric printing process may include irradiating a photocurable resin with light of at least a first wavelength and light of a second wavelength different from the first wavelength to form a three-dimensional object by multicolor photopolymerization (particularly two-color photopolymerization). Specific examples of the first and second wavelengths are given further above. Therefore, this at least one irradiation process may include multicolor photopolymerization (particularly two-color photopolymerization) of the photocurable resin, which provides numerous advantages for manufacturing three-dimensional objects, such as faster manufacturing speed, greater design complexity, and higher resolution.

[0077] Irradiating a photocurable resin with light of a first wavelength causes one or more photoinitiator molecules in the photocurable resin to transfer from an initial state to an intermediate state. Compared with the initial state, the optical properties of the intermediate state are changed, allowing one or more photoinitiator molecules in the intermediate state to absorb light of a second wavelength. By absorbing the second wavelength of light, one or more photoinitiator molecules are transferred from the intermediate state to a reactive state, thereby locally initiating the polymerization of the photocurable resin to form at least one three-dimensional object.

[0078] Photocurable resins can be photocurable monomeric resins or photocurable oligomer resins, for example, they may include acrylates, methacrylates, thiols + alkenes, epoxides, oxetanes, oxetanes, or vinyl ethers. Multicolor photopolymerization can include multiphoton photopolymerization of photocurable resins, particularly two-photon photopolymerization. Photopolymerization of photocurable resins is typically achieved by irradiating the photocurable resin with light of a first wavelength, particularly simultaneously with light of a second wavelength different from the first wavelength. This causes the photoinitiator molecules of one or more photoinitiators in the photocurable resin, for example, by absorbing light of the first wavelength, to transform from an initial state (in which one or more photoinitiator molecules (substantially) do not absorb light of the second wavelength) to an intermediate state in which their optical properties change compared to the initial state, enabling the photoinitiator molecules of one or more photoinitiators in the intermediate state to absorb light of the second wavelength, thereby causing one or more photoinitiator molecules to transition from the intermediate state to a reactive state and locally initiate the polymerization of the photocurable resin to form at least one three-dimensional object.

[0079] Photoinitiator molecules of one or more photoinitiators can reverse-react from an intermediate state back to their initial state, for example, through thermal induction. Therefore, at the printing temperature of the photocurable resin, the intermediate state can return to its initial state via thermal reaction. Preferably, at the corresponding printing temperature, the intermediate state can return to its initial state via thermal reaction through a reaction or reaction sequence having one or more rate constants (where the highest rate constant is greater than k = 0.01 s⁻¹). Particularly preferred is that the rate constant of at least one thermal reverse reaction is greater than 0.02 s⁻¹, more preferably greater than 0.05 s⁻¹, more preferably greater than 0.1 s⁻¹, even more preferably greater than 1.0 s⁻¹, and most preferably greater than 5.0 s⁻¹. Therefore, this rate constant can be in the range of 0.05 s⁻¹ to 1.0 s⁻¹, or in any other range consisting of the above values. A higher rate constant can improve the resolution of the printed three-dimensional object.

[0080] Alternatively, at the corresponding printing temperature of the photocurable resin, the intermediate state may substantially not return to the initial state through thermal reaction. Preferably, the intermediate state can return to the initial state through thermal reaction at the printing temperature via a reaction or reaction sequence having one or more rate constants, wherein at least one rate constant is less than k = 100 s⁻¹. Particularly preferred is that the rate constant of at least one thermal reverse reaction is less than 1 s⁻¹, more preferably less than 0.1 s⁻¹, more preferably less than 0.01 s⁻¹, even more preferably less than 0.001 s⁻¹, and most preferably less than 0.0001 s⁻¹. Thus, the rate constant can be in the range of 0.1 s⁻¹ and 0.0001 s⁻¹, or in any other range consisting of the values ​​described above.

[0081] Furthermore, the intermediate state can be substantially prevented from returning to the initial state through thermal reaction at the printing temperature of the photocurable resin. Preferably, the intermediate state can be returned to the initial state through thermal reaction at the printing temperature via a reaction or reaction sequence having one or more rate constants (the highest rate constant being less than k = 100 s⁻¹). Particularly preferred is that the highest rate constant of the thermal reverse reaction is less than 1 s⁻¹, more preferably less than 0.1 s⁻¹, more preferably less than 0.01 s⁻¹, even more preferably less than 0.001 s⁻¹, and most preferably less than 0.0001 s⁻¹. Therefore, this rate constant can be in the range of 0.1 s⁻¹ and 0.0001 s⁻¹, or in any other range consisting of the values ​​described above.

[0082] Examples of suitable photocurable resins and suitable photoinitiators for photocurable resins can be found in US5230986A, WO2020245456A1, WO2023034398A1, WO2023034404A1, WO2023034402A1, WO2023220461A1, and WO2023220463A1, the contents of which are incorporated herein by reference.

[0083] In other exemplary embodiments of the method, altering at least one process parameter of the volumetric printing process may include spatially and / or temporally altering at least one printing parameter (particularly at least one printing parameter affecting the curing or curing behavior of the photocurable resin) during at least one irradiation process. Therefore, at least one irradiation process may be subject to coordinated and intentional spatial and / or temporal control, which may include coordinated and intentional control of alterations to at least one printing parameter (particularly at least one printing parameter affecting the curing behavior of the photocurable resin) during at least one irradiation process. The corresponding spatial and / or temporal alteration of the at least one printing parameter may also include a change in the focus of light of a first wavelength and / or a change in the size of one or more images or one or more image elements (e.g., pixels) of light of a second wavelength. The corresponding spatial and / or temporal alteration of the at least one printing parameter may also involve the number of irradiation steps in which one or more volumetric elements (e.g., voxels) of the photocurable resin are irradiated by light of the first wavelength and / or the second wavelength. Therefore, the corresponding spatial and / or temporal alteration of the at least one printing parameter may also include a change in the number of irradiation steps in which one or more volumetric elements (e.g., voxels) of the photocurable resin are irradiated. A corresponding spatial and / or temporal change in at least one printing parameter may also involve the direction and / or speed of movement of the photocurable resin, particularly relative to the direction and / or speed of movement of the photosheet formed by the light of the first wavelength. Therefore, a corresponding spatial and / or temporal change in at least one printing parameter may also include a change in the direction and / or speed of movement of the photocurable resin, particularly relative to the direction and / or speed of movement of the photosheet formed by the light of the first wavelength.

[0084] Based on spatial and / or temporal variations in at least one printing parameter, at least one irradiation process may include: printing at least one first portion of a three-dimensional object with different printing parameters relative to at least one other portion of the three-dimensional object. The corresponding first object portion may include one or more first volume elements (e.g., voxels) of photocurable resin located at one or more first locations within the photocurable resin. The corresponding other object portion may include one or more other volume elements (e.g., voxels) of photocurable resin located at one or more other locations within the photocurable resin. This other volume element may be a volume element located following the first volume element.

[0085] Spatial and / or temporal changes in at least one printing parameter can enable each volume element of the photocurable resin to be irradiated with individual printing parameters, especially those printing parameters that affect, for example, energy, energy density, energy intensity, etc., which act on the corresponding volume element in at least one irradiation process.

[0086] The printing parameters for corresponding volume elements of a photocurable resin can be selected based on the position of that volume element within the photocurable resin and its position within the 3D object to be printed. For example, different printing parameters can be used for one or more volume elements of a photocurable resin adjacent to or close to an uncured or uncured photocurable resin, compared to one or more volume elements adjacent to or close to a cured or uncured photocurable resin. In this way, spatial and / or temporal variations in at least one printing parameter can be specifically implemented to account for the so-called proximity effect, which refers to the phenomenon where a volume element adjacent to another cured volume element exhibits specific curing behavior, such as curing more easily or faster, unlike the curing behavior of volume elements not adjacent to another cured or photopolymerized volume element. It is worth noting that the proximity effect often leads to undesirable structural anisotropy in 3D objects and associated undesirable lower shrinkage and deformation in conventional volumetric printing methods.

[0087] Therefore, according to the corresponding embodiments, the method can print three-dimensional objects with higher structural isotropy and lower undesirable shrinkage and deformation based on spatial and / or temporal changes in at least one printing parameter during at least one irradiation process, thereby resulting in three-dimensional objects exhibiting higher geometric accuracy and structural fidelity.

[0088] According to another exemplary embodiment, spatially and / or temporally altering at least one printing parameter (particularly printing parameters affecting the curing behavior of a photocurable resin) can include irradiating the photocurable resin with light of a first wavelength first, followed by irradiating the photocurable resin with light of a second wavelength. Therefore, altering at least one printing parameter can include spatially and / or temporally irradiating the photocurable resin with light of a first wavelength first, followed by irradiating the photocurable resin with light of a second wavelength. Thus, one or more volume elements of the three-dimensional object to be printed can be irradiated with light of a first wavelength before being irradiated with light of a second wavelength. The corresponding one or more volume elements of the photocurable resin can particularly include first volume units of the three-dimensional object to be printed. In other words, at least one irradiation process can include spatially and / or temporally irradiating one or more volume elements with light of a first wavelength (using only) followed by irradiating subsequent volume elements with light of a first wavelength (and typically also with light of a second wavelength). Irradiating the volume elements of the photocurable resin with only light of a first wavelength can preactivate these volume elements, thereby improving their curing effect when subsequently irradiated with light of both the first and second wavelengths, and thus improving the structural properties of the three-dimensional object to be printed.

[0089] An example of irradiating the photocurable resin with a first wavelength of light before irradiating it with light of a second wavelength (spatially) can include: irradiating the photocurable resin with light of the first wavelength starting from a first position p1, and irradiating it with light of the second wavelength starting from a second position p2, wherein the second position p2 is located behind the first position p1 in the forming direction. The second position is typically located within the volume of the photocurable resin constituting the three-dimensional object to be printed, and therefore also located inside the three-dimensional object to be printed. Specifically, the second position can be located within the volume of the photocurable resin constituting the outer boundary or edge of the three-dimensional object to be printed, and therefore also located on the surface of the three-dimensional object to be printed. Therefore, the three-dimensional object to be printed can be contained in a portion located behind the second position in the forming direction, or the three-dimensional object itself can be formed behind the second position in the forming direction. Thus, the second position can contain a first volume element (e.g., a first voxel) of the three-dimensional object to be printed relative to the forming direction. The first position can also be a position within the volume of the photocurable resin constituting the three-dimensional object to be printed, and therefore also located inside the three-dimensional object to be printed. In particular, the first position can also be a position within the volume of the photocurable resin that does not constitute the three-dimensional object to be printed, and therefore is also a position located outside the three-dimensional object to be printed.

[0090] Another example of irradiating the photocurable resin with light of the first wavelength before irradiating it with light of the second wavelength (in time) could be: irradiating the photocurable resin with light of the first wavelength starting from a first time t1, and irradiating it with light of the second wavelength starting from a second time t2, where t2 > t1. Typically, the second time corresponds to the moment when the volume of photocurable resin constituting the three-dimensional object to be printed is irradiated. Specifically, the second time could correspond to the moment when the volume of photocurable resin constituting the outer boundary or edge of the three-dimensional object to be printed is irradiated, i.e., the moment when a position on the surface of the three-dimensional object to be printed is irradiated. Therefore, the three-dimensional object to be printed could include portions to be printed after the second time, or the printing of the three-dimensional object could be completed after the second time. Thus, the second time could include the moment when the first volume element (e.g., the first voxel) of the three-dimensional object to be printed is printed relative to the forming direction. The first time could also correspond to the moment when the volume of photocurable resin constituting the three-dimensional object to be printed is irradiated. However, the first time could also correspond to the moment when the volume of photocurable resin not constituting the three-dimensional object to be printed is irradiated.

[0091] According to another exemplary embodiment, changing at least one printing parameter (particularly printing parameters affecting the curing behavior of the photocurable resin) spatially and / or temporally may include irradiating the photocurable resin with light of a first wavelength after irradiating it with light of a second wavelength. Therefore, changing at least one printing parameter may include irradiating the photocurable resin with light of a second wavelength first, and then irradiating it with light of a first wavelength, both spatially and / or temporally. Thus, one or more volume elements of the three-dimensional object to be printed may be irradiated with light of a first wavelength after being irradiated with light of a second wavelength. The corresponding one or more volume units of the photocurable resin may particularly include the final volume element of the three-dimensional object to be printed. In other words, at least one irradiation process may include irradiating one or more volume elements with light of a first wavelength after, both spatially and / or temporally, the previous volume units have been irradiated with light of a second wavelength (and typically also with light of a first wavelength). Irradiating the volume elements of the photocurable resin with only light of a first wavelength can result in post-activation of these volume elements, thereby further curing them after irradiation with both light of a first and second wavelength, thereby improving the structural properties of the three-dimensional object to be printed.

[0092] An example of irradiating the photocurable resin with light of a second wavelength (spatially) and then irradiating it with light of a first wavelength can include: the endpoint of irradiating the photocurable resin with the second wavelength is located at a third position p3, while the endpoint of irradiating the photocurable resin with the first wavelength is located at a fourth position p4, wherein the fourth position p4 is located behind the third position p3 in the forming direction. The third position is typically located within the volume of the photocurable resin constituting the three-dimensional object to be printed, and therefore is also located inside the three-dimensional object to be printed. Specifically, the third position can be located within the volume of the photocurable resin constituting the outer boundary or edge of the three-dimensional object to be printed, and therefore is also located on the surface of the three-dimensional object to be printed. Therefore, the three-dimensional object to be printed can be a portion located in front of the third position in the forming direction, or the three-dimensional object itself can be formed in front of the third position in the forming direction. Thus, the third position can contain the last volume element of the three-dimensional object to be printed relative to the forming direction, such as the last voxel. The fourth position can also be a position within the volume of the photocurable resin constituting the three-dimensional object to be printed, and therefore is also located inside the three-dimensional object to be printed. In particular, the fourth position can also be a position within the volume of the photocurable resin that does not constitute the three-dimensional object to be printed, and therefore is also a position located outside the three-dimensional object to be printed.

[0093] Another example of irradiating the photocurable resin with light of the second wavelength (in time) followed by irradiating it with light of the first wavelength includes: irradiating the photocurable resin with light of the second wavelength ends at a third time t3, while irradiating it with light of the first wavelength ends at a fourth time t4, where t4 > t3. The third time typically corresponds to the moment when the volume of photocurable resin constituting the three-dimensional object to be printed is irradiated. Specifically, the third time may correspond to the moment when the volume of photocurable resin constituting the outer boundary or edge of the three-dimensional object to be printed is irradiated, i.e., the moment when the position corresponding to the surface of the three-dimensional object to be printed is irradiated. Therefore, the three-dimensional object to be printed may include portions that need to be printed before the third time, or the printing of the three-dimensional object may be completed before the third time. Thus, the third time may correspond to the moment when the last volume element (e.g., the last voxel) of the three-dimensional object to be printed is printed in the forming direction. The fourth time may also correspond to the moment when the volume of photocurable resin constituting the three-dimensional object is irradiated. However, the fourth time may also correspond to the moment when the volume of photocurable resin not constituting the three-dimensional object is irradiated.

[0094] Therefore, altering at least one printing parameter (particularly printing parameters affecting the curing behavior of the photocurable resin) spatially and / or temporally can include irradiating the photocurable resin with light of a first wavelength within a volume separate from the volume of the three-dimensional object to be printed (particularly adjacent volumes, and more particularly directly adjacent volumes), particularly with light of only the first wavelength, especially where this volume is spatially and / or temporally located before and / or after the volume of the three-dimensional object to be printed relative to at least one forming direction of the three-dimensional object. In this way, pre-activation or post-activation of the photocurable resin can be achieved, thereby positively influencing the structural properties of the three-dimensional object to be printed.

[0095] Therefore, spatially and / or temporally, irradiating the photocurable resin with light of the first wavelength before or after irradiating it with light of the second wavelength typically includes irradiating only the volume elements in the photocurable resin that do not constitute the three-dimensional object to be printed with light of the first wavelength. Relative to the forming direction of the three-dimensional object to be printed, these volume elements may be located before or in front of the volume elements constituting the three-dimensional object, preferably before or in front of the first volume element of the three-dimensional object; or they may be located after or behind the volume elements constituting the three-dimensional object, preferably after or behind the last volume element of the three-dimensional object.

[0096] Similarly, it can be envisioned that the volume elements of the photocurable resin that do not constitute part of the three-dimensional object to be printed can be irradiated (only) with light of the second wavelength, and therefore the above description can also be applied accordingly to light of the second wavelength.

[0097] According to another exemplary embodiment, changing at least one printing parameter (particularly printing parameters affecting the curing behavior of the photocurable resin) spatially and / or temporally may include: irradiating the photocurable resin with light of a first wavelength and / or a second wavelength, and changing the energy (particularly the energy intensity) of the first wavelength and / or the second wavelength of light spatially and / or temporally along at least one direction. Changing the energy (particularly the energy intensity) of the first wavelength and / or the second wavelength of light spatially and / or temporally along at least one direction can also have a positive impact on the structural properties of the three-dimensional object to be printed, for example, because it allows control over the amount of energy received by each volume element of the three-dimensional object to be printed, thereby achieving the desired curing of the corresponding volume element. Therefore, problems caused by differences in the degree of curing of different volume units of the three-dimensional object to be printed (which typically also leads to undesirable structural anisotropy in the three-dimensional object) can be overcome or at least mitigated. Similarly, the proximity effect (as described above) can also be overcome or at least mitigated, because one or more volume elements adjacent to a cured or photopolymerized volume element can be irradiated with different energies relative to one or more volume elements not adjacent to a cured or photopolymerized volume element.

[0098] Specifically, changing the energy or energy intensity spatially and / or temporally can include: the energy level of the light of the first wavelength can be varied from a first energy level to at least a second energy level, which is higher or lower than the first energy level. Therefore, during at least one irradiation process, the energy or energy intensity of the light of the first wavelength can dynamically or gradually increase or decrease spatially and / or temporally, particularly relative to a nominal value, which can be, but is not limited to, a minimum or maximum energy or energy intensity.

[0099] Additionally or alternatively, changing the energy or energy intensity of the second wavelength of light spatially and / or temporally may include varying the energy level of the second wavelength of light from a first energy level to at least a second energy level, which is higher or lower than the first energy level. Therefore, during at least one irradiation process, the energy or energy intensity of the second wavelength of light may dynamically or gradually increase or decrease spatially and / or temporally, particularly relative to a nominal value, which may be, but is not limited to, a minimum or maximum energy level or energy intensity level.

[0100] As an example, changing the energy (particularly the energy intensity) of light of a second wavelength in space and / or time along at least one direction can include: changing the energy or energy density of one or more image elements (e.g., pixels) of an image corresponding to the cross-sectional geometry of a three-dimensional object to be printed in space and / or time. In other words, the projection of one or more images can each contain image elements with different energies or energy densities. Changing the energy or energy density of individual image elements can include changing the energy level or energy density level between a minimum energy level or minimum energy density level and a maximum energy level or maximum energy density level. Similarly, changing the energy or energy density of individual lines or points can also include changing the energy level or energy density level between a minimum energy level or minimum energy density level and a maximum energy level or maximum energy density level. Changing the energy or energy density of the corresponding image elements, points, or lines can be achieved by controlling the corresponding irradiation device used to generate the projection of the image, point, or line.

[0101] As another example, spatially and / or temporally changing the energy (particularly the energy intensity) of light of a second wavelength along at least one direction can include: spatially and / or temporally changing one or more image elements (e.g., pixels) of an image corresponding to the cross-sectional geometry of the three-dimensional object to be printed, and / or spatially and / or temporally changing one or more image elements (e.g., pixels) of an image not corresponding to the cross-sectional geometry of the three-dimensional object to be printed, such that the energy or energy intensity does not affect the curing of the photocurable resin. Therefore, spatially and / or temporally changing the energy (particularly the energy intensity) of light of a second wavelength can include: setting the energy or energy intensity spatially and / or temporally to a level that does not cause the photocurable resin to cure, or setting it to a level that causes insufficient photocuring. However, it is also conceivable that spatially and / or temporally changing the energy (particularly the energy intensity) of light of a second wavelength can include setting the energy or energy intensity spatially and / or temporally to a level that causes over-curing of the photocurable resin. Specifically, varying the energy (particularly the energy intensity) of the second wavelength of light in space and / or time along at least one direction can include irradiating a first volume element of the three-dimensional object to be printed with light of a second wavelength at an intensity higher than that of other volume elements of the three-dimensional object to be printed with, relative to the forming direction. In this way, a means for compensating for proximity effects is provided.

[0102] According to another exemplary embodiment, in the initial volume of the three-dimensional object to be printed, a photocurable resin is irradiated with light of a first wavelength at a first energy level, the first energy level being a higher energy level than a nominal energy level or a second energy level. The initial volume occupies at least 10%, particularly at least 9%, more particularly at least 8%, more particularly at least 7%, more particularly at least 6%, more particularly at least 5%, more particularly at least 4%, more particularly at least 3%, more particularly at least 2%, more particularly at least 1%, and more particularly at least 1% of the spatial extension of the three-dimensional object to be printed in at least one direction. It is at most 0.9%, more particularly at most 0.8%, more particularly at most 0.7%, more particularly at most 0.6%, more particularly at most 0.5%, more particularly at most 0.4%, more particularly at most 0.3%, more particularly at most 0.2%, more particularly at most 0.1%, more particularly at most 0.09%, more particularly at most 0.08%, more particularly at most 0.07%, more particularly at most 0.06%, more particularly at most 0.05%, more particularly at most 0.04%, more particularly at most 0.03%, more particularly at most 0.02%, more particularly at most 0.01%. In at least one direction, irradiating the photocurable resin in the initial volume of the three-dimensional object to be printed with light of a first wavelength at a higher energy level can, in particular, compensate for or at least reduce the proximity effect, thereby obtaining, for example, a three-dimensional object with lower structural anisotropy and better structural performance.

[0103] Alternatively, the photocurable resin may be irradiated with light of a first wavelength at a first energy level (which may be higher than a nominal energy level or a second energy level) during an initial time period of the total duration of at least one irradiation process, particularly during the initial time period of the total duration of the process for printing a three-dimensional object by multicolor photopolymerization of the photocurable resin during at least one irradiation process. This initial time period may be at most 10 seconds, particularly at most 9 seconds, more particularly at most 8 seconds, more particularly at most 7 seconds, more particularly at most 6 seconds, more particularly at most 5 seconds, more particularly at most 4 seconds, more particularly at most 3 seconds, more particularly at most 2 seconds, and more particularly... It is at most 1 second, more specifically at most 0.9 seconds, more specifically at most 0.8 seconds, more specifically at most 0.7 seconds, more specifically at most 0.6 seconds, more specifically at most 0.5 seconds, more specifically at most 0.4 seconds, more specifically at most 0.3 seconds, more specifically at most 0.2 seconds, more specifically at most 0.1 seconds, more specifically at most 0.09 seconds, more specifically at most 0.08 seconds, more specifically at most 0.07 seconds, more specifically at most 0.06 seconds, more specifically at most 0.05 seconds, more specifically at most 0.04 seconds, more specifically at most 0.03 seconds, more specifically at most 0.02 seconds, more specifically at most 0.01 seconds. The corresponding time period may correspond to at least one time segment of an irradiation process in which at least the first frame, particularly at most the first 100 frames, more particularly at most the first 90 frames, more particularly at most the first 80 frames, more particularly at most the first 70 frames, more particularly at most the first 60 frames, more particularly at most the first 50 frames, more particularly at most the first 40 frames, more particularly at most the first 30 frames, more particularly at most the first 20 frames, more particularly at most the first 10 frames are irradiated into the photocurable resin.

[0104] According to another exemplary embodiment, changing at least one printing parameter in space and / or time, particularly printing parameters affecting the curing behavior of the photocurable resin, can include: changing the focusing parameters (e.g., size and / or position) of the focal point of a first wavelength of light, and / or changing at least one image element (e.g., pixel) or image parameters (e.g., size and / or position) of the image projected by the second wavelength of light. Thus, the focusing parameters of the focal point of the first wavelength of light can serve as printing parameters that can be changed during at least one irradiation process, thereby affecting the curing result of the forming area and the feature resolution of the three-dimensional object to be printed in space and / or time. These focusing parameters include, for example, the size and / or position of the focal point, focal length, depth of focus, and depth of field. The focal point may comprise multiple beams, particularly multiple (substantially) parallel beams, which extend through the photocurable resin, for example, in the form of a light sheet. The change in the focusing parameters of the first wavelength of light can be achieved by one or more optical elements (e.g., (movable) lenses), for example, arranged on an irradiation apparatus for generating light of the first wavelength and corresponding beams for extending through the photocurable resin. Corresponding optical elements can form part of the focusing adjustment device of the irradiation apparatus, which can be configured to adjust one or more focusing parameters of the first wavelength of light. Alternatively, a projected image of the second wavelength of light (which may include an image projection corresponding to the cross-sectional geometry of the three-dimensional object to be printed) or image parameters (e.g., size and / or position) of at least one image element can serve as printing parameters that can be adjusted during at least one irradiation process, thereby affecting the curing result of the forming area and the feature resolution of the three-dimensional object to be printed spatially and / or temporally. One or more image parameters of the second wavelength of light image can be changed by one or more optical elements (e.g., movable lenses, pixel generators, etc.) arranged on the irradiation apparatus configured to generate the second wavelength of light and an image corresponding to the cross-sectional geometry of the three-dimensional object to be printed. These optical elements can form part of the image adjustment device of the irradiation apparatus, which can be configured to adjust one or more image parameters of the second wavelength of light. The image adjustment device can be a component comprised of the hardware and / or software of a light projection device (e.g., a digital light projection device).

[0105] According to another exemplary embodiment, changing the energy of the second wavelength of light spatially and / or temporally can include: changing the energy or energy distribution of at least a portion (e.g., pixels) of at least one projected image corresponding to the cross-sectional geometry of the three-dimensional object to be printed, or changing the energy or energy distribution of at least one point or line of at least one light beam corresponding to the cross-sectional geometry of the three-dimensional object to be printed. Specifically, the energy of the second wavelength of light can be changed along at least one direction, such that, relative to the forming direction, an upstream portion of the three-dimensional object to be printed is exposed to different energy levels of the second wavelength of light compared to a downstream portion of the three-dimensional object to be printed. As described above, changing the energy of the second wavelength of light spatially and / or temporally can generate three-dimensional objects with lower structural anisotropy and better structural performance.

[0106] As an example, changing the energy or energy intensity of light of a second wavelength in space and / or time can include: changing the energy or energy intensity of at least a portion of at least one image, particularly at least one image element (e.g., a pixel) of the image in a sequence comprising at least three energy levels E1, E2, and E3, or energy intensity levels E1, E2, and E3, wherein the energy level or energy intensity level changes from E1 to E2, and E2 > E1; and the energy level or energy intensity level changes from E2 to E3, and E2 > E3, particularly E3 > E1, or for example, E1 = 0. In particular, the first energy level E1 can be assigned to one or more volume elements of the photocurable resin, in which the photocurable resin does not require or only requires minimal photopolymerization; these volume elements of the photocurable resin can include volume elements that do not constitute part of the three-dimensional object to be printed. Therefore, the first energy level can also be (substantially) zero (E1 = 0). In particular, the second energy level E2 can be assigned to one or more volume units of the photocurable resin, which constitute part of the three-dimensional object to be printed. Specifically, the second energy level E2 can be allocated to one or more volume elements of the photocurable resin that constitute part of at least a first volume element of the three-dimensional object to be printed relative to the forming direction, or constitute a first volume element of the three-dimensional object to be printed relative to the forming direction. Specifically, the third energy level E3 can be allocated to one or more volume elements of the photocurable resin that constitute part of other volume elements of the three-dimensional object to be printed, which are located behind the first volume element of the three-dimensional object to be printed relative to the forming direction. Furthermore, a fourth energy level E4 can be implemented and allocated to one or more volume elements of the photocurable resin that do not constitute part of the three-dimensional object to be printed. Specifically, the fourth energy level E4 can be allocated to volume elements of the photocurable resin located behind the last volume element of the photocurable resin constituting the three-dimensional object to be printed. Therefore, the fourth energy level E4 can also be (essentially) zero (E4=0).

[0107] According to another exemplary embodiment, changing at least one printing parameter (particularly printing parameters affecting the curing behavior of the photocurable resin) spatially and / or temporally may include irradiating the photocurable resin with light of a first wavelength and / or a second wavelength during at least one irradiation process, when at least one forming region does not move relative to the container, or when at least one forming region moves at a variable rate of motion lower than the nominal rate of motion. This variable rate of motion may also be zero. Therefore, the rate of motion used to move at least one forming region, particularly relative to the container, is also a printing parameter that can be changed spatially and / or temporally, for example, to achieve the printing of three-dimensional objects with higher structural isotropy.

[0108] As an example, during at least one irradiation process, when at least one forming region does not move relative to the container, or when at least one forming region moves at a varying rate of motion below the nominal rate of motion, irradiating the photocurable resin with light of a first wavelength and / or a second wavelength may include: irradiating the photocurable resin with light of the first wavelength when the photocurable resin moves relatively slowly relative to the container, or even does not move at all, such that the corresponding volume units of the photocurable resin are irradiated by light of the first wavelength for a relatively long period of time. During this period, for example, the second wavelength of light may contain a constant image or a still image. Alternatively, during this period, for example, no second wavelength of light is irradiated into the photocurable resin and the working volume.

[0109] According to another exemplary embodiment, changing at least one printing parameter (particularly printing parameters affecting the curing behavior of the photocurable resin) spatially and / or temporally may further include irradiating the photocurable resin with light of a first wavelength and / or a second wavelength as at least one forming region moves along two different directions. Therefore, the direction of movement of at least one forming region, particularly relative to the container, is also a printing parameter that can be changed spatially and / or temporally, for example, to achieve the printing of three-dimensional objects with higher structural isotropy.

[0110] As an example, at least one forming region can be irradiated with light of a first wavelength and / or a second wavelength while moving along a first motion path in a first motion direction, particularly irradiated with light of only the first wavelength; and at least one forming region can be irradiated with light of the first wavelength and / or a second wavelength while moving along a second motion path in a second motion direction (particularly in the opposite direction to the first direction), particularly irradiated with light of both the first and second wavelengths simultaneously. Specifically, the first motion direction can be a direction of movement toward or away from an irradiation device (particularly a digital light projection device) used to implement the method, while the second motion direction can be the opposite, or vice versa, wherein the irradiation device generates light of the second wavelength.

[0111] As another example, the first motion path can differ from the second motion path, particularly in length. In particular, the first motion path can be shorter than the second motion path. Therefore, when at least one forming area moves along the first motion path, the time for light of the first wavelength to irradiate the photocurable resin may be shorter than when at least one forming area moves along the second motion path.

[0112] According to another exemplary embodiment, changing at least one printing parameter (particularly printing parameters affecting the curing behavior of the photocurable resin) spatially and / or temporally can include (particularly applicable to embodiments of the method where multiple independent three-dimensional objects need to be printed (particularly simultaneously)): for example, by setting the starting position and / or starting time and / or ending position and / or ending time for irradiating the photocurable resin with light of a second wavelength to print a first three-dimensional object can be different from the starting position and / or starting time for irradiating the photocurable resin with light of a second wavelength to print another three-dimensional object. In particular, this exemplary embodiment enables the photocurable resin to continue being irradiated with light of a second wavelength even after the printing of at least one three-dimensional object has been completed, thereby resulting in higher structural fidelity for the first three-dimensional object printed. It is noteworthy that this exemplary embodiment is particularly applicable to cases where multiple three-dimensional objects to be printed are arranged laterally. Therefore, their forming directions are parallel to each other.

[0113] According to another exemplary embodiment, at least one irradiation process may include: in a first irradiation step, irradiating a photocurable resin with light of a first wavelength and light of a second wavelength to form a prepolymerized three-dimensional pre-construct; and, in at least one subsequent irradiation step (particularly after the first irradiation step), irradiating the prepolymerized three-dimensional pre-construct with light of the first wavelength and light of the second wavelength to form a three-dimensional object. Therefore, the number of individual irradiation steps can also serve as a printing parameter that varies spatially and / or temporally. It is noteworthy that this embodiment may include forming a prepolymerized pre-construct in the first irradiation step, the shape and / or size of which corresponds (substantially) to the three-dimensional object to be printed. However, the pre-construction and the actual three-dimensional object to be printed may differ in the degree of curing of the photocurable resin. In other words, the degree of curing of the photocurable resin in the pre-construction may be lower; for example, the degree of curing of the pre-construction may be so low that it cannot be processed. Nevertheless, printing the final three-dimensional object using a corresponding intermediate pre-construction can significantly improve the structural performance of the final three-dimensional object.

[0114] As an example, in the first irradiation step, a photocurable resin can be irradiated with light of a first wavelength and light of a second wavelength to form a prepolymerized pre-component; in the second irradiation step, the prepolymerized pre-component is irradiated with light of the first wavelength and light of the second wavelength to further polymerize the prepolymerized pre-component, and the second irradiation step can be repeated multiple times. It is noteworthy that in the first irradiation step, the forming region can move along a first motion path in a first motion direction; in at least one second irradiation step, the forming region can move along a second motion path in a second motion direction, particularly in a direction opposite to the first motion direction.

[0115] Typically, in the first irradiation step, the photocurable resin is irradiated with light of a first wavelength to form a prepolymerized photocurable resin; in at least one subsequent irradiation step (especially after the first irradiation step is completed), the prepolymerized photocurable resin is irradiated with light of a first wavelength and light of a second wavelength to form a three-dimensional object to be printed.

[0116] Specifically, in the first irradiation step, a photocurable resin can be irradiated with light of a first wavelength and light of a second wavelength to form a prepolymerized photocurable resin; in at least one subsequent irradiation step (especially after the first irradiation step), the prepolymerized photocurable resin is irradiated with light of the first wavelength and light of the second wavelength, thereby forming a three-dimensional object to be printed. Specifically, in the first irradiation step, the intensity of the second wavelength light may be lower than the intensity required for the photocurable resin to cure, or lower than the intensity required for forming the three-dimensional object to be printed. Specifically, in the first irradiation step, the intensity distribution of the second wavelength light is non-uniform. More specifically, in the first irradiation step, the second wavelength light has a lower intensity in the outer region near the container wall defining the working volume, and a higher intensity in the inner region of the working volume (e.g., the center of the working volume). For example, the second wavelength light can be projected as an image with higher intensity in the corresponding inner region. This image may be, for example, a grayscale image or a white image. Furthermore, printing the final three-dimensional object through the intermediate prepolymerized photocurable resin can improve the structural properties of the three-dimensional object to be printed.

[0117] According to another exemplary embodiment of the method, the forming time of the three-dimensional object is at most 1 minute for every 1 mm of extension in at least one direction. Therefore, the method can be implemented at high printing speeds, which is another exemplary printing parameter that can affect the curing behavior of the photocurable resin, thereby influencing the formation of undesirable deformations of at least one three-dimensional object.

[0118] A second aspect of the invention relates to a system for manufacturing three-dimensional objects by volumetric printing. The system is specifically configured to perform the method of the first aspect of the invention, such that all descriptions relating to the method of the first aspect of the invention are applicable to the system of the second aspect of the invention, and vice versa. The system may include at least the following components: a volumetric printing apparatus for performing a volumetric printing process to manufacture at least one three-dimensional object based on data containing geometric model information of at least one three-dimensional object to be manufactured, wherein the volumetric printing process is performed based on a plurality of process parameters; a determining device for determining at least one attribute of the at least one three-dimensional object printed in step a), and generating determining information indicating at least one determined attribute of the at least one three-dimensional object printed in step a); and a controller for comparing at least one determined attribute of the at least one three-dimensional object printed in step a) with at least one reference attribute (in particular, a nominal attribute or a target attribute) of a reference three-dimensional object (in particular, a nominal attribute or a target attribute), and generating comparison information indicating the comparison result. It is noteworthy that the controller is specifically configured to perform the following steps: determining whether a comparison result indicates that the deviation between at least one determined attribute of at least one three-dimensional object printed in step a) and at least one reference attribute of a reference three-dimensional object exceeds a threshold; if the comparison result indicates that the deviation between at least one determined attribute of at least one three-dimensional object printed in step a) and at least one reference attribute of a reference three-dimensional object exceeds the threshold, then changing at least one of the following: at least one parameter of the geometric model of the three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process. Furthermore, at least one controller is configured to repeat steps a)–d) or steps a)–e) using at least one modified parameter of the geometric model of the three-dimensional object to be manufactured and / or the modified parameter of at least one process parameter of the volumetric printing process until the comparison result indicates that the deviation between at least one determined attribute of the three-dimensional object printed in step a) and at least one reference attribute of the reference three-dimensional object does not exceed the threshold.

[0119] This system can be configured to print at least one three-dimensional object via volumetric printing based on photopolymerization (particularly multicolor photopolymerization, and more particularly two-color photopolymerization). Therefore, the volumetric printing apparatus for this system can be a two-color voxel lithography apparatus, i.e., an apparatus configured to perform the basic principles of two-color voxel lithography. The basic principles of two-color voxel lithography are described in WO2020 / 245456A1, the contents of which are incorporated herein by reference.

[0120] Therefore, volumetric printing equipment typically includes a container for holding photocurable resin. This container can be movably supported in at least one direction. This at least one direction can be, or include, the forming direction of the three-dimensional object to be printed.

[0121] The volumetric printing apparatus may also include a two-color irradiation device configured to irradiate a photocurable resin inside a container. The two-color irradiation device is configured to irradiate the photocurable resin with light of a first wavelength, and particularly simultaneously with light of a second wavelength different from the first wavelength. The two-color irradiation device may include at least one first irradiation device and at least one second irradiation device, the first irradiation device including at least one first light source for generating light of the first wavelength, and the second irradiation device including at least one second light source for generating light of the second wavelength. The two-color irradiation device may be configured to generate a light sheet using the first wavelength light, wherein the light sheet extends in the plane of the light sheet. Furthermore, the two-color irradiation device may also be configured to generate a light projection of the second wavelength light, wherein the light projection intersects the light sheet at a certain angle, particularly at an angle of approximately 90°. The light projection of the second wavelength light can be generated by simultaneously or sequentially emitting multiple beams of the second wavelength. Therefore, the light projection of the second wavelength light can include at least one of the following: an image of the second wavelength light, which may contain image elements (e.g., pixels) of different intensities, thereby forming a non-uniform or uniform intensity distribution of the image; or, sequential filling at different locations, the filling content of which may contain dots or lines, thereby forming an image of the second wavelength light, which may contain image elements (e.g., pixels) of different intensities, thereby forming a non-uniform or uniform intensity distribution of the image.

[0122] At least one first irradiation device may therefore include at least one light source configured to irradiate light of a first wavelength onto a photocurable resin to produce at least one first light projection forming a light sheet. The light sheet may include multiple beams extending in a common plane. For example, at least one first irradiation device may be constructed as a laser or a light-emitting diode, or may include a laser or a light-emitting diode. At least one first irradiation device may also include at least one optical element, such as at least one of the following: a Powell lens, a cylindrical lens, a diffractive optical element, a beam expander, a collimating optical element, etc. Additionally or optionally, at least one first irradiation device may include a light deflection unit for deflecting light onto the photocurable resin, such as a (movable or rotatable) mirror, a galvanometer scanner, or a polygon scanner. At least one first irradiation device may be configured to change the focal point or at least one focal parameter of the at least one first light projection within a working volume, particularly at least one of the following: focal position, focal length, depth of focus, or depth of field. In particular, at least one first irradiation device may be configured to change the focal point or at least one focal parameter according to the size of the forming area. At least one first irradiation device may include one or more controllers configured to change the focal point or at least one focal parameter of at least one first light projection within the working volume, particularly changing at least one of the following parameters: focal position, focal length, depth of focus, or depth of field. Additionally or optionally, the at least one first irradiation device may include one or more optical elements, such as lenses, particularly adjustable lenses, configured to change the focal point or at least one focal parameter of at least one first light projection within the working volume, particularly at least one of the following: focal position, focal length, depth of focus, or depth of field. The wavelength range of the light emitted or irradiated by the at least one first irradiation device may be, for example, 350 nm–500 nm, particularly 375 nm–450 nm, more particularly 385 nm–440 nm, more particularly 395 nm–420 nm, and more particularly 400 nm–410 nm. The light of the first wavelength may comprise a wavelength spectrum, particularly a wavelength spectrum that at least partially covers the corresponding ranges described above. For example, the first wavelength may be approximately 375 nm. Generally, when selecting the first wavelength, the photochemical properties of the photoinitiator molecules of the photocurable resin should be considered, especially the photochromic properties.

[0123] At least one second irradiation device may therefore include at least one second light source configured to continuously project an image corresponding to the cross-sectional geometry of the three-dimensional object to be printed, or a plurality of points or lines corresponding to the cross-sectional geometry of the three-dimensional object to be printed. The second irradiation device may be constructed as an image projection device, particularly a digital light projection device or a directional light emitting device, or include the aforementioned devices. At least one second irradiation device may also include one or more light projection optics. At least one second irradiation device may be configured to change the size of at least one image or at least one image element (e.g., a pixel) in the image projection. At least one second irradiation device may include one or more controllers configured to change the size of at least one image or at least one image element (e.g., a pixel) in the image projection. Additionally or optionally, at least one second irradiation device may include one or more optical elements, such as lenses, configured to change the size of at least one image or at least one image element (e.g., a pixel) in the image projection. The wavelength range of light emitted or irradiated by at least one second irradiation device can be, for example, 400 nm–1000 nm, particularly 425 nm–750 nm, even more particularly 450 nm–675 nm, and even more particularly 500 nm–650 nm. The second wavelength of light may encompass a wavelength spectrum, and in particular, may at least partially cover the wavelength spectrum of the aforementioned corresponding ranges. Generally, when selecting the second wavelength, at least the photochemical properties of the photoinitiator molecules of the photocurable resin, particularly the photochromic properties, should be considered.

[0124] As described above, a two-color irradiation apparatus can be configured to generate an image projection using light of a second wavelength, wherein the light projection intersects the light sheet at a certain angle, particularly at an angle of approximately 90°. Therefore, the two-color irradiation apparatus can typically be configured to irradiate the first wavelength of light at a first angle (particularly 0° to 180°) and the second wavelength of light at a second angle (particularly 0° to 180°), the first and second angles being angles of 0° to 180°, particularly relative to the main extending plane of at least one forming region. The corresponding angles can be particularly between 15° and 165°, more particularly between 30° and 150°, and even more particularly between 90° and 150° or between 30° and 90°. Specifically, the second wavelength of light can be irradiated at a 90° angle relative to the first wavelength of light.

[0125] Optionally, the system may further include: a post-processing device, such as a post-curing apparatus, which may include an energy source (e.g., a radiation source and / or an irradiation source) for applying post-curing energy to the three-dimensional object to be post-cured; and / or a transfer device for transferring at least one three-dimensional object within the system, such as from a printing device to a post-processing device.

[0126] The third aspect of the invention relates to a computer program product comprising instructions for causing a controller of a system of the second aspect of the invention to perform the steps of the method of the first aspect of the invention, such that all descriptions relating to the method of the first aspect of the invention and the system of the second aspect of the invention also apply to the computer program product of the third aspect of the invention, and vice versa. Attached Figure Description

[0127] Based on these and other advantages and features that will subsequently become apparent, a more complete understanding of the invention can be obtained through the following description with reference to the accompanying drawings, wherein:

[0128] Figure 1 A schematic diagram of a volumetric printing apparatus for printing three-dimensional objects, according to an exemplary embodiment, is shown.

[0129] Figure 2 A schematic diagram of a system for manufacturing three-dimensional objects by volumetric printing, according to an exemplary embodiment, is shown.

[0130] Figure 3 A flowchart is shown for a method of manufacturing a three-dimensional object by volumetric printing according to an exemplary embodiment;

[0131] Figure 4 It shows according to Figure 3 An exemplary embodiment of a three-dimensional object manufactured by the method shown, and a reference object; and

[0132] Figures 5a to 5c A schematic diagram of an exemplary embodiment of a method for manufacturing three-dimensional objects by volumetric printing, according to another exemplary embodiment, is shown. Detailed Implementation

[0133] Figure 1 A schematic diagram of a volumetric printing apparatus 10 for printing three-dimensional objects according to an exemplary embodiment is shown. The apparatus 10 is configured to volumetrically print at least one three-dimensional object by performing two-color photopolymerization on a photocurable resin 20, and the apparatus 10 includes an irradiation device 30 for performing an irradiation process in which the photocurable resin 20 is irradiated with light of a first wavelength L1 and light of a second wavelength L2 to form a three-dimensional object in at least one direction by two-color photopolymerization. This direction is in… Figure 1 The arrow P1 indicates the forming direction of the 3D object to be printed, which may include or can include that direction. For example... Figure 1 As shown, light of the first wavelength L1 and light of the second wavelength L2 intersect in the forming region FZ.

[0134] The first wavelength of light L1 can comprise a lightsheet consisting of multiple beams passing through the photocurable resin 20. For example, the individual beams can form a light plane. This light plane can be or comprise a light plane in which one or more beams, particularly (substantially) parallel beams, extend adjacent to each other such that there are no gaps between directly adjacent beams. Notably, at least some directly adjacent beams may also partially overlap. Alternatively, the light plane can be or comprise a light plane in which one or more beams extend adjacent to each other such that there are gaps between directly adjacent beams. The individual beams can be generated by a directional light emitting device (e.g., a laser device), which can form part of the irradiation apparatus of a volumetric printing device for implementing the method.

[0135] The second wavelength of light L2 may include an image projection corresponding to the cross-sectional geometry of the three-dimensional object to be printed, or multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object to be printed. The individual points or lines may form a pattern, such as a hatch pattern. The corresponding projection may be generated by a light projection device (e.g., a digital light projection device), which may constitute part of the irradiation device of the volumetric printing apparatus used to implement the method. The corresponding points or lines may be generated by a directional light emitting device (e.g., a laser device), which may constitute part of the irradiation device 30 of the apparatus. As will be further explained below, both the light projection device and the directional light emitting device can serve as examples of the second irradiation device 32.

[0136] Specifically, apparatus 10 may be or include volumetric printing equipment, particularly a two-color voxel lithography apparatus, i.e., an apparatus configured to perform the basic principles of two-color voxel lithography. The basic principles of two-color voxel lithography are described in WO2020 / 245456A1, the contents of which are incorporated herein by reference.

[0137] The device 10 includes a controller 40 implemented in hardware and / or software, which is configured to change at least one printing parameter spatially and / or temporally during the printing process, particularly process parameters that affect the curing (behavior) of the photocurable resin 20.

[0138] The apparatus 10 includes a container 50 for containing a photocurable resin 20. The container 50 defines a container volume 51, which may contain a working volume in which at least one three-dimensional object can be printed. One or more walls of the container 50 may be made of a material that allows the photocurable resin within the container 50 to be irradiated by a first wavelength L1 and a second wavelength L2. Therefore, the corresponding material may be a transparent material that is transparent relative to the first wavelength L1 and the second wavelength L2. The corresponding transparent material may be or include glass or polymers, such as polycarbonate, polymethyl methacrylate, or cyclic olefin copolymers.

[0139] Container 50 can be in at least one direction (e.g.) Figure 1 (As shown by the double arrow P2 in the diagram) it is movably supported, for example by a related drive device 60, such as a motor. Figure 1 As shown, the at least one direction can be or include the forming direction of the three-dimensional object to be printed. It is worth noting that the drive device 60 can also be associated with the first irradiation device 31 of the irradiation device 30 of the device 10, and move the first irradiation device 31 in at least one direction in a similar manner.

[0140] The apparatus 10 also includes an irradiation device 30, which may be a dual-color irradiation device configured to irradiate the photocurable resin 20 within the container 50 using light of a first wavelength L1 and light of a second wavelength L2. Specifically, the irradiation device 30 may be configured to simultaneously irradiate the photocurable resin 20 within the container 50 with light of the first wavelength L1 and light of the second wavelength L2. The irradiation device 30 may be configured to generate a light sheet using light of the first wavelength L1, wherein the light sheet extends in the plane of the light sheet. Furthermore, the irradiation device 30 may also be configured to generate, for example, a light projection using light of the second wavelength L2, wherein the light projection intersects the light sheet at a certain intersection angle, particularly an intersection angle of approximately 90°.

[0141] like Figure 1 As shown, the irradiation device 30 may include: a first irradiation device 31, which includes at least one first light source for generating and emitting light L1 of a first wavelength; and a second irradiation device 32, which includes at least one second light source for generating and emitting light L2 of a second wavelength.

[0142] The first irradiation device 31 may include at least one light source configured to generate and irradiate light L1 of a first wavelength onto the photocurable resin 20 to form a light sheet. For example, the first irradiation device 31 may constitute a laser or a light-emitting diode, or include a laser or a light-emitting diode. The first irradiation device 31 may also include at least one optical element, which may include, for example, at least one of the following: a Powell lens, a cylindrical lens, a diffractive optical element, a beam expander, a collimating optical element, etc. Additionally or optionally, the first irradiation device 31 may include a light deflection unit, such as a (movable, particularly rotatable) mirror, a galvanometer scanner, or a polygon scanner, for deflecting light onto the photocurable resin 20. The first irradiation device 31 may be configured to change the focal point or focal parameter of at least one corresponding first light projection within the working volume, particularly at least one of the following parameters: focal position, focal length, depth of focus, or depth of field. In particular, the first irradiation device 31 may be configured to change the focal point or at least one focal parameter according to the size of the forming area. The first irradiation device 31 may include one or more controllers configured to change the focal point or focal parameters of at least one corresponding first light projection within the working volume, particularly at least one of the following parameters: focal position, focal length, depth of focus, or depth of field. Additionally or optionally, the first irradiation device 31 may include one or more optical elements, such as lenses, particularly adjustable or variable lenses, for changing the focal point or focal parameters of at least one corresponding first light projection within the working volume, particularly at least one of the following parameters: focal position, focal length, depth of focus, or depth of field. The light L1 generated by the first irradiation device 31 may include the following wavelength ranges: for example, 350 nm to 500 nm, particularly 375 nm to 450 nm, more particularly 385 nm to 440 nm, more particularly 395 nm to 420 nm, more particularly 400 nm to 410 nm. The light L1 of the first wavelength may comprise a wavelength spectrum, particularly a wavelength spectrum that at least partially covers the aforementioned corresponding ranges. For example, the first wavelength may be approximately 375 nm. Typically, the photochemical properties of the photoinitiator molecules of the photocurable resin 20, particularly the photochromic properties, are considered when selecting the first wavelength.

[0143] The second irradiation device 32 may include at least one second light source configured to continuously emit images of light L2 of a second wavelength onto the photocurable resin 20, wherein each image may correspond to a specific cross-section of the three-dimensional object to be printed, or to multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object to be printed. The second irradiation device 32 may be constructed as or include an image projection device, particularly a digital light projection device or a directional light emission device. The second irradiation device 32 may also include one or more light projection optics. Therefore, the second irradiation device 32 can generate image elements, such as voxels, with specific focal points and / or sizes. The second irradiation device 32 may be configured to change the size of at least one image or at least one image element (e.g., a pixel) of the projected image. The second irradiation device 32 may include one or more controllers configured to change the size of at least one image or at least one image element (e.g., a pixel) of the image projection. Additionally or optionally, the second irradiation device 32 may include one or more optical elements (e.g., lenses) configured to change the size of at least one image or at least one image element (e.g., a pixel) of the image projection. The light L2 emitted or irradiated by the second irradiation device 32 may include the following wavelength range: 400 nm to 1000 nm, particularly 425 nm to 750 nm, more particularly 450 nm to 675 nm, and even more particularly 500 nm to 650 nm. The second wavelength of light L2 may comprise a wavelength spectrum, particularly one that at least partially covers the aforementioned corresponding range. Typically, when selecting the second wavelength, at least the photochemical properties of the photoinitiator molecules of the photocurable resin 20, particularly its photochromic properties, should be considered.

[0144] As described above, the irradiation device 30 can generally be configured to irradiate light L1 of a first wavelength at a first angle, particularly from 0° to 180°, and light L2 of a second wavelength at a second angle, particularly at an angle of 0° to 180° relative to the extending direction of the first wavelength light L1. The aforementioned angle can be particularly between 15° and 165°, more particularly between 30° and 150°, even more particularly between 90° and 150°, or between 30° and 90°. In particular, the second wavelength light L2 can intersect the first wavelength light L1 at a 90° angle (e.g., ...). Figure 1 (Example shown).

[0145] Irradiating the photocurable resin 20 with light of the first wavelength L1 causes one or more photoinitiator molecules in the photocurable resin 20 to transfer from an initial state to an intermediate state. Compared with the initial state, the optical properties of the intermediate state are changed, so that one or more photoinitiator molecules in the intermediate state can absorb light of the second wavelength L2, thereby causing one or more photoinitiator molecules to transfer from the intermediate state to a reactive state by absorbing light of the second wavelength L2, and locally initiating the polymerization of the photocurable resin 20 to form at least one three-dimensional object.

[0146] The photocurable resin 20 can be a photocurable monomer resin or a photocurable oligomer resin, for example, it may include acrylates, methacrylates, thiols + alkenes, epoxides, oxetanes, oxetanes, or vinyl ethers. Multicolor photopolymerization can include multiphoton photopolymerization, particularly two-photon photopolymerization, of the photocurable resin 20. Photopolymerization of the photocurable resin 20 is achieved by irradiating the photocurable resin 20 with light of a first wavelength L1 and, particularly simultaneously, light of a second wavelength L2. This causes one or more photoinitiator molecules in the photocurable resin 20 to transform from an initial state (in which one or more photoinitiator molecules (substantially) do not absorb light of the second wavelength L2) to an intermediate state in which their optical properties change compared to the initial state. In the intermediate state, one or more photoinitiator molecules absorb light of the second wavelength L2, thereby transferring one or more photoinitiator molecules from the intermediate state to a reactive state, locally initiating the polymerization of the photocurable resin 20 to form at least one three-dimensional object.

[0147] For example, suitable photoinitiators for the corresponding photocurable resin 20 may be found in: US5230986A, WO2020245456A1, WO2023034398A1, WO2023034402A1, WO2023220461A1, and WO2023220463A1, the contents of which are incorporated herein by reference.

[0148] Figure 2 A schematic diagram of a system 100 for manufacturing three-dimensional objects by volumetric printing, according to an exemplary embodiment, is shown. The system 100 is specifically configured to perform a method for volumetric printing at least one three-dimensional object, the method being combined with... Figure 3 The exemplary embodiments will be described in detail below.

[0149] like Figure 2 As shown, system 100 may include at least the following components: volumetric printing equipment (e.g., Figure 1The device 10 is used to perform a volumetric printing process to manufacture at least one three-dimensional object based on data containing geometric model information of at least one three-dimensional object to be manufactured, wherein the volumetric printing process is performed based on multiple process parameters; a determining device 70 is used to determine at least one attribute of the at least one three-dimensional object printed in step a), and generate determining information indicating at least one determined attribute of the at least one three-dimensional object printed in step a); and a controller 80 is used to compare at least one determined attribute of the at least one three-dimensional object printed in step a) with at least one reference attribute (in particular, nominal or target attribute) of a reference three-dimensional object (in particular, nominal or target attribute), and generate comparison information indicating the comparison result.

[0150] Optionally, the system 100 may further include: a post-processing device 90, such as a post-curing device, which may include an energy source (e.g., a radiation source and / or a heat source) for applying post-curing energy to the three-dimensional object to be post-cured; and / or a transfer device 95 for transferring the three-dimensional object within the system 100, such as from the device 10 to the post-processing device 90.

[0151] It is worth noting that controller 80 is specifically configured to execute [the commands] in [the specified manner]. Figure 3 The methods and steps are described in the flowchart.

[0152] like Figure 3 As shown, this method enables the manufacture of three-dimensional objects through volumetric printing. The three-dimensional objects manufactured according to this method can be technical components or part of a technical component. In particular, the technical component can be an optical component, such as an optical lens or an optical lens array. Furthermore, this method is also applicable to other technical components and three-dimensional objects.

[0153] The method includes a first step (step a) for performing a volumetric printing process to manufacture at least one three-dimensional object. Therefore, step a) includes a volumetric printing process in which at least one three-dimensional object is manufactured. The direct result of the volumetric printing process in step a) may be at least one green blank, which may require one or more post-processing steps (e.g., one or more post-curing steps) to be converted into at least one blank. Step a) can be performed using device 10.

[0154] The volumetric printing process in step a) is performed based on data containing geometric model information of at least one 3D object to be manufactured. This data can be or includes CAD data or STL data. Therefore, this data can contain information describing the model surfaces (particularly triangulated surfaces) of the at least one 3D object to be manufactured, such as consisting of at least one of the following: unit normals, vectors, vertices, etc. Therefore, this data can be provided in CAD data format or STL data format. Of course, other data formats can also be considered.

[0155] The volumetric printing process in step a) is based on or includes multiple process parameters. As a non-limiting example, these process parameters (which may be or include irradiation parameters) may in particular relate to the polymerization of a photocurable resin provided in the working volume, which polymerizes locally to form at least one three-dimensional object through volumetric printing. As another non-limiting example, these process parameters may relate to the movement of a movable device of the volumetric printing apparatus used to perform step a), for example, the movement of a container defining a corresponding working volume relative to an irradiation device configured to emit light of at least one wavelength toward the corresponding working volume, or vice versa. Typically, one, several, or all of the process parameters in the volumetric printing process can cause undesirable deformation effects, such as bending effects, warping effects, etc., in the three-dimensional object to be printed.

[0156] The method includes a second step (step b) for determining at least one attribute of at least one three-dimensional object printed in step a) and generating determination information indicating at least one determined attribute. Therefore, step b) is typically implemented using a determining device (e.g., determining device 70), which may include one or more determining elements (e.g., sensors) configured to determine at least one attribute of at least one three-dimensional object printed in step a) and generate determination information indicating at least one determined attribute. For example, the corresponding determination information may include raw data (data further processed by a controller or data that can be further processed). In either case, the corresponding determination information can directly or indirectly indicate at least one (determined) attribute of at least one three-dimensional object printed during the volumetric printing process in step a).

[0157] Typically, the respective properties of each three-dimensional object that can be determined in step b) may include at least one chemical property and / or at least one physical property of the three-dimensional object. Non-limiting examples of these chemical and / or physical properties will be provided below.

[0158] The method includes a third step (step c), which compares at least one determined property of at least one three-dimensional object with that of a reference three-dimensional object RO (see [reference]). Figure 4The comparison process involves comparing at least one reference attribute of at least one 3D object RO with at least one reference attribute, and generating comparison information indicating the comparison result. It is noteworthy that the reference 3D object RO can be a real 3D reference object or a digital representation of a 3D reference object, such as a 3D reference object model of the 3D object to be manufactured, particularly a CAD model or STL model. Therefore, step c) is typically implemented by a comparison device 81, which can be or includes hardware and / or software implementations, and is therefore typically a computer-implemented comparison device configured to compare at least one determined attribute of at least one 3D object with at least one reference attribute and generate comparison information indicating the comparison result. The comparison device 81 may include or communicate with a data storage device 82, which may be or include a data server storing one or more reference attributes, such as corresponding predefined or predefined nominal or target attributes of one or more predefined or predefined 3D objects. The comparison device 81 may include one or more algorithms suitable for comparing at least one determined attribute of at least one three-dimensional object with at least one corresponding reference attribute and generating comparison information indicating the comparison result. For example... Figure 2 As shown, the comparison device 81 and / or the data storage device 82 may form part of the controller 80, or at least be assigned to the controller 80.

[0159] It is worth noting that the corresponding reference attribute (e.g., the corresponding predefined or predefined nominal or target attribute) can be a desired or necessary attribute of the at least one three-dimensional object to be manufactured, particularly with respect to its intended application and / or function. Similarly, the corresponding reference three-dimensional object (e.g., the corresponding predefined or predefined nominal or target three-dimensional object) can be a desired or necessary three-dimensional object, particularly with respect to its intended application and / or function. Therefore, the corresponding predefined or predefined nominal or target attribute can correspond to a desired or necessary attribute of the at least one three-dimensional object to be manufactured, and the predefined or predefined nominal or target three-dimensional object can correspond to a desired or necessary three-dimensional object to be manufactured.

[0160] The method includes a fourth step (step d) for determining whether the comparison result indicates that the deviation (if present) between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold. Step d) can also be implemented using a comparison device 81, which may include or communicate with a data storage device 82, which may be or include a data server storing the corresponding threshold. The comparison device 81 may include one or more algorithms adapted to determine whether the comparison result indicates that the deviation (if present) between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold.

[0161] For example, a deviation of at least 0.1%, particularly at least 1%, more particularly at least 5%, more particularly at least 10%, more particularly at least 15%, and more particularly at least 20% from a determined attribute and related predefined or predefined nominal or target attributes can be considered a corresponding deviation and trigger a change to at least one of the following: at least one parameter of the geometric model of the 3D object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process. However, the corresponding threshold typically depends at least on the specific attribute and the specific 3D object, and therefore usually needs to be set individually for each specific attribute and each specific 3D object (or at least a specific type of specific object), for example, based on experimental results, computer simulations, etc.

[0162] If the comparison results indicate that the deviation between at least one determined attribute of at least one 3D object and at least one reference attribute exceeds at least one threshold (see...), then... Figure 3If the statement in step a) indicates that the method is correct, then the method may include changing at least one of the following: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process. Therefore, the method is capable of and includes: determining deviations between one or more determined properties of the at least one three-dimensional object printed in step a) and corresponding one or more reference properties (e.g., predefined or pre-defined nominal or target properties). If these deviations are considered significant, i.e., the deviations exceed at least one corresponding threshold, then the method is capable of actively and intentionally changing at least one of the following: at least one geometric model parameter of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process, to at least partially reduce or even completely compensate for the determined deviations, for example, by compensation in one or more subsequent volumetric printing processes. Therefore, the step of changing at least one of the following is intended to reduce or completely compensate for the determined deviations: at least one geometric model parameter of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process. Therefore, by changing at least one of the following steps: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process, particularly including changing at least one of the following when repeating one, several, or all steps of the method: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process, thereby reducing or fully compensating for the determined deviation.

[0163] Therefore, altering at least one of the following steps—at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process—may include performing operations taken in previous volumetric printing and / or post-processing processes that have successfully altered one or more specific properties of the three-dimensional object by intentionally changing at least one of the following: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, or at least one process parameter of the post-processing process. For example, one or more process parameters of the current or upcoming volumetric printing process can be changed, for example, by changing one or more irradiation parameters that have had a positive impact on one or more properties of the printed three-dimensional object in a previous volumetric printing process. To give a more specific example, previous experimental results, simulations, etc., may have shown that irradiation parameters associated with the polymerization of a particular photocurable resin, such as irradiation intensity, irradiation time, irradiation rate, etc., can reduce undesirable deformation effects of the printed three-dimensional object, such as deformation caused by bending, warping, etc. Therefore, changing these corresponding irradiation parameters, for example by increasing or decreasing one or more of them, can reduce undesirable deformation effects of at least one three-dimensional object.

[0164] Similar methods are also applicable to other process parameters in the volumetric printing process. Furthermore, similar methods are also applicable to changes to at least one of the following: at least one parameter of the geometric model of the 3D object to be manufactured, and at least one process parameter of the post-processing, such as parameters related to the post-curing of the 3D object, such as post-curing strength, post-curing time, post-curing speed, etc.

[0165] If the comparison results indicate that the deviation between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold, the method may include not only changing at least one of the following: at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, at least one process parameter of the post-processing process, but also repeating steps a)-d) using at least one modified parameter of the geometric model of the at least one three-dimensional object to be manufactured and / or at least one modified process parameter of the volumetric printing process and / or at least one modified process parameter of the post-processing process until the comparison results indicate that, for at least one other three-dimensional object, the deviation between at least one determined attribute of the at least one other three-dimensional object and at least one reference attribute does not exceed the threshold.

[0166] Therefore, the method may include a fifth step (step e) which includes: if the comparison result indicates that the deviation between at least one determined attribute of at least one three-dimensional object and at least one reference attribute exceeds at least one threshold, then changing at least one of the following: at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, at least one process parameter of the post-processing process, and repeating steps a)-d) once or more using at least one changed parameter of the geometric model of at least one three-dimensional object and / or at least one changed process parameter of the volumetric printing process and / or at least one changed process parameter of the post-processing process, until the comparison result indicates that the deviation between at least one determined attribute of the three-dimensional object or another three-dimensional object and at least one reference attribute no longer exceeds at least one threshold.

[0167] The above-described method steps improve the manufacturing of 3D objects via volumetric printing because steps b) and c) include at least intrinsic control over one or more properties of the current 3D object manufactured in step a) to conform to one or more desired or required predefined or predefined nominal or target properties. Furthermore, the method includes an active step in step e) that modifies at least one parameter of the geometry of the at least one 3D object to be manufactured, at least one process parameter of the volumetric printing process, at least one process parameter of the post-processing process, and prints at least one other 3D object based on the corresponding modified parameters; this other 3D object typically has improved properties, particularly less undesirable deformation relative to the current (or previous) 3D object. Therefore, the optimization process for manufacturing 3D objects via volumetric printing, particularly an iterative optimization process, can be implemented in one or more stages, where each stage typically includes performing steps a)–d) or steps a)–e) as described above.

[0168] It is worth noting that one or more steps of the method can be implemented at least semi-automatically, and especially fully automatically, for example, by the controller 80 of system 100. Specifically, changes to at least one of the following can be implemented at least semi-automatically, and especially fully automatically: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process. Therefore, the method can optimize the manufacturing method of volumetric printing at least one three-dimensional object in at least a semi-automatic manner, and especially in a fully automatic manner.

[0169] The steps of determining at least one property of at least one three-dimensional object and generating determination information indicating at least one determined property of at least one three-dimensional object may include determining at least one chemical property and / or physical property of at least one three-dimensional object.

[0170] At least one chemical property may be or include at least one of the following: the chemical composition of at least one three-dimensional object printed in step a); the chemical reaction state of at least one three-dimensional object printed in step a), particularly the polymerization state of at least one three-dimensional object printed in step a). The corresponding chemical property of at least one three-dimensional object can be determined by a determining device, which may be or include at least one of the following: a spectroscopic device, for example, a device for performing spectroscopic analysis, particularly a device for performing ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), or Raman spectroscopy, or a device for performing differential scanning calorimetry (DSC).

[0171] At least one physical property may be or include at least one of the following: acoustic, optical, geometric, mechanical, surface, electrical, thermal, or magnetic properties of at least one three-dimensional object printed in step a). The corresponding physical property of at least one three-dimensional object may be determined by a determining device, which may be or include at least one of the following: an interferometer, an impedance meter, an optical sensor (e.g., a camera or a one-dimensional or multi-dimensional scanner), a microscope, a conductivity or resistance meter, a thermal conductivity or thermal resistivity meter, a testing machine (e.g., for conducting tests under mechanical loads, such as bending tests, compressive strength tests, tensile strength tests, flexural strength tests, shear strength tests, torsion tests, hardness tests), a roughness meter (profilometer), a magnetometer, etc. In addition, a testing device may be used, configured to test at least one function of the at least three-dimensional object according to its intended application and / or function, for example, to test at least one of the following functions of the at least three-dimensional object: optical function, geometric function, mechanical function, surface function, electrical function, thermal function, magnetic function, etc., to determine whether the at least three-dimensional object printed in step a) can achieve the desired or required function in terms of the intended application and / or function of the at least three-dimensional object.

[0172] At least one determined property of at least one three-dimensional object can indicate deformation of the at least one three-dimensional object, particularly deformation caused by bending, warping, etc., of the at least one three-dimensional object, more specifically, deformation caused by bending, warping, etc., during the volume printing process and / or post-processing. Any deformation of the at least one three-dimensional object may cause at least one property of the at least one three-dimensional object (e.g., but not limited to geometric properties) to deviate from at least a reference property of a reference three-dimensional object. Therefore, the determining device 70 may include one or more algorithms adapted to derive the deviation related to the reference property of the reference three-dimensional object from the determined properties of the at least one printed three-dimensional object, for example, through data correlation principles, artificial intelligence principles, machine learning principles, etc. However, it is also conceivable, particularly based on measurement methods, to determine the corresponding deviation by comparing the determined properties of the at least one three-dimensional object with the relevant reference properties of the reference three-dimensional object; therefore, any determination of the properties of a three-dimensional object mentioned herein may also typically include the measurement of the corresponding properties of the three-dimensional object.

[0173] As described above, at least one property of at least one three-dimensional object can also be determined by a measuring device configured to measure at least one chemical and / or physical property of at least one three-dimensional object. Non-limiting examples of various measuring devices include at least one of the exemplary determining devices 70 described above. Therefore, any of the exemplary determining devices 70 described above can also be a measuring device or include a measuring device, and vice versa.

[0174] Changing at least one parameter of the geometric model of at least one 3D object to be manufactured may include altering information in a CAD file (particularly an STL file) that describes or represents the model of the at least one 3D object to be manufactured. Therefore, within the framework of this method (particularly in step e), a revised CAD or STL file can be generated, where each revision of the CAD or STL file is designed to, and thus reduces, unwanted deformation effects, thereby positively impacting the properties (e.g., geometric accuracy) of at least one further printed 3D object. Changing the corresponding information in the CAD or STL file that describes or represents the model of the at least one 3D object to be manufactured may, in particular, reposition and / or reorient one or more vertices, for example, by locally or globally changing the vertex density. Furthermore, one or more other image parameters of the corresponding CAD or STL file may be changed accordingly. Typically, at least one image parameter of the model of the at least one 3D object to be manufactured can be changed, particularly pixels, voxels, or vertices. Therefore, the information in the CAD file (particularly an STL file) that describes or represents the model of the at least one 3D object to be manufactured may be or include, for example, pixels, voxels, vectors, or vertices of the model of the at least one 3D object to be manufactured. Surprisingly, experiments show that changing image parameters (e.g., by repositioning and / or reorienting one or more pixels, voxels, vectors, or vertices) can reduce undesirable deformation effects on one or more subsequently printed 3D objects, thereby positively impacting the geometric accuracy of printed 3D objects.

[0175] As described above, data containing geometric model information of at least one three-dimensional object to be manufactured, such as a CAD model or STL model of the corresponding geometric model of the at least one three-dimensional object to be manufactured, can be further processed by suitable data processing means (e.g., algorithms, software, etc.) to generate a projection or image of one or more cross-sectional geometries of the at least one three-dimensional object to be manufactured. As described above, during the volumetric printing process in step a), the corresponding projection image or image can be projected onto the working volume from one or more directions to cause the photocurable resin provided within the working volume to undergo a polymerization reaction. The photocurable resin is locally polymerized, thereby forming at least one three-dimensional object through volumetric printing.

[0176] The inventors unexpectedly discovered that directly altering at least one parameter of the geometric model of at least one three-dimensional object to be manufactured is more advantageous than processing projections or images of one or more cross-sectional geometries of the at least one three-dimensional object obtained from a corresponding model of the at least one three-dimensional object, for the following reasons. For example, directly altering at least one parameter in the geometric model of the at least one three-dimensional object to be manufactured is more advantageous in terms of the accuracy of altering at least one parameter, because it changes the original data, rather than any data resulting from further processing of the original data (e.g., corresponding projections or corresponding images). Furthermore, for example, altering at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured requires fewer computational resources compared to further processing the corresponding projected image or corresponding image. Thus, the efficiency of altering at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured can also be improved, for example, because directly altering at least one parameter of the geometric model of the at least one three-dimensional object to be manufactured may require fewer and / or simpler computational steps.

[0177] It is worth noting that changes to information in a CAD file (especially an STL file) regarding or representing a model of at least one 3D object to be manufactured can be implemented at least semi-automatically, and in particular fully automatically, based on an algorithm suitable for changing information in a CAD file (especially an STL file) regarding or representing a model of the 3D object to be manufactured according to at least one target criterion. The corresponding target criterion may be or include one or more target properties of the 3D object to be printed. The corresponding target properties may include chemical and / or physical properties of at least one 3D object to be printed. As mentioned above, chemical properties may include at least one of the following: the chemical composition of at least one 3D object printed in step a), and the chemical reaction state of at least one 3D object printed in step a), particularly the polymerization state of at least one 3D object printed in step a). As mentioned above, physical properties may include at least one of the acoustic, optical, geometric, mechanical, surface, electrical, thermal, or magnetic properties of at least one 3D object printed in step a). As a non-limiting example, the corresponding algorithm could be or incorporate linear regression principles to reduce unwanted deformation effects, thereby (particularly through iteration) improving the properties of at least one 3D object to be printed, especially increasing the fidelity of the at least one 3D object to be printed. However, other computational models and principles such as artificial intelligence and machine learning can also be considered.

[0178] Changing at least one process parameter of the volumetric printing process may include changing at least one parameter of the irradiation process of the volumetric printing process, which, as described above, includes irradiating a photocurable resin within the working volume with light of at least one wavelength. The corresponding process parameter may be or include at least one of the following: the duration of irradiation of the photocurable resin with light of at least one wavelength, the start time of irradiation of the photocurable resin with light of at least one wavelength, the end time of irradiation of the photocurable resin with light of at least one wavelength, the intensity of the light used to irradiate the photocurable resin, the wavelength of the light used to irradiate the photocurable resin, the printing speed, the printing direction, the orientation of the three-dimensional object within the working volume (particularly the principal axis of the three-dimensional object), and the movement path of the working volume during the irradiation process, etc.

[0179] By altering at least one process parameter of the volumetric printing process, optionally or additionally, at least one parameter of the photocurable resin used for volumetric printing of three-dimensional objects may be changed. Furthermore, the corresponding parameters of the photocurable resin may be or include chemical parameters of the photocurable resin, such as the chemical composition of the photocurable resin, the concentration and / or type of the photoinitiator, and / or physical parameters of the photocurable resin, such as density, temperature, absorption and / or transmittance of light of at least one wavelength, viscosity of the photocurable resin, etc.

[0180] Furthermore, the transfer parameters of at least one three-dimensional object can be changed by a transfer device (e.g., transfer device 95), such as a transfer robot, for transferring the three-dimensional object from a volumetric printing device (e.g., device 10) to a post-processing device (e.g., post-processing device 90), etc. The corresponding transfer parameters of the at least one three-dimensional object may be or include changes to at least one of the following: the gripping position of the at least one three-dimensional object used for transfer (at which the at least one three-dimensional object is gripped, for example, by a gripping device), the transfer path used for transferring the at least one three-dimensional object, the transfer speed (and the relevant forces acting on the at least one three-dimensional object during transfer), etc.

[0181] Changing at least one process parameter of a post-processing procedure (which may typically be or include a post-curing process) may include changing at least one of the following: the duration of the post-processing procedure, the start time of the post-processing procedure, the end time of the post-processing procedure, the energy, intensity, or wavelength of the post-processing procedure (particularly the energy, intensity, or wavelength of radiation applied to at least one three-dimensional object during the post-processing procedure), the temperature or temperature profile of the post-processing procedure, the wavelength of the post-processing procedure, the speed of the post-processing procedure, and at least one parameter of at least one process gas (e.g., an inert gas) in the post-processing procedure, such as chemical parameters (e.g., chemical composition, concentration, etc.), physical parameters, flow parameters, concentration parameters, etc. In particular, the corresponding temperature or temperature profile associated with the sintering process, which is an example of a corresponding post-processing procedure, may be changed. The corresponding temperature profile may include at least one of the following: a positive temperature ramp (heating ramp), a negative temperature ramp (cooling ramp), or a temperature plateau. The corresponding positive or negative temperature ramp may be, for example, a linear ramp or a non-linear ramp.

[0182] In other exemplary embodiments of the method, at least step c) can be performed by a controller (e.g., controller 80), particularly by at least one algorithm of the controller, which is configured to compare at least one determined attribute of a 3D object with at least one reference attribute (particularly a target attribute) of a reference 3D object (particularly a target 3D object), and generate comparison information indicating the comparison result. Similarly, steps d) and e) (at least in relation to determining whether a threshold is exceeded) can also be performed by a controller (particularly by at least one algorithm of the controller), which is configured to determine whether the comparison result indicates that the deviation between at least one determined attribute of at least one 3D object and at least one reference attribute of a reference 3D object exceeds a threshold; if the comparison result indicates that the deviation between at least one determined attribute of a 3D object and at least one reference attribute of a reference 3D object exceeds a threshold, then the control changes at least one of the following: at least one parameter of the geometric model of the 3D object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process.

[0183] Specifically, the controller 80 may include one or more algorithms for modifying at least one of the following according to at least one target criterion: at least one parameter of the geometric model of at least one three-dimensional object to be manufactured, at least one process parameter of the volumetric printing process, and at least one process parameter of the post-processing process. The corresponding target criterion may be or include one or more target properties of the at least one three-dimensional object to be printed. The corresponding target properties may be or include chemical and / or physical properties of the three-dimensional object to be printed. As described above, chemical properties may include at least one of the following: the chemical composition of the at least one three-dimensional object printed in step a), and the chemical reaction state of the at least one three-dimensional object printed in step a), particularly the polymerization state of the at least one three-dimensional object printed in step a). As further described above, physical properties may include at least one of the following: acoustic properties, optical properties, geometric properties, mechanical properties, surface properties, electrical properties, thermal properties, or magnetic properties of the at least one three-dimensional object printed in step a).

[0184] Figure 4 It shows that according to Figure 3 Exemplary embodiments of three-dimensional objects O1–O3 manufactured by the method shown, and a reference object RO. Specifically, Figure 4 The implementation of this method is shown to iteratively reduce exemplary undesirable deformations of 3D objects (see exemplary curved top portions of 3D objects O1 and O2), thereby enabling the creation of a 3D object O3 corresponding to a reference 3D object RO after one or more stages of the method's execution. More specifically, Figure 4 The diagram illustrates how, in each stage of performing steps a)–e) of the method, the corresponding undesired deformation is reduced, and in particular, iteratively reduced. In this example, after the first stage of the method, a 3D object O1 with significant deformation is obtained; after an exemplary subsequent stage of the method, a 3D object O2 with less deformation compared to 3D object O1 is obtained; after another exemplary subsequent stage of the method, a 3D object O3 with very little or almost no deformation is obtained, such that its shape corresponds to the shape of the reference object RO, and the deviation (if any) between at least one determined property of this 3D object and at least one reference property of the reference 3D object RO does not exceed at least one threshold. It is worth noting that this principle can be applied to any property of the corresponding 3D object, and is therefore not limited to the exemplary property of shape.

[0185] Figures 5a to 5c A schematic diagram of an exemplary embodiment of a method for manufacturing a three-dimensional object by volumetric printing according to another exemplary embodiment is shown. It is noteworthy that this volumetric printing process includes multicolor photopolymerization, particularly two-color photopolymerization, and does not include computational axial lithography.

[0186] Specifically, the method (particularly including multicolor light polymerization, especially two-color light polymerization) may include a data processing step in which data processing (particularly slicing) of a geometric model of at least one three-dimensional object is performed to generate an image corresponding to the cross-sectional geometry of the three-dimensional object, or multiple points or lines corresponding to the cross-sectional geometry of the three-dimensional object (see [link to relevant documentation]). Figure 5a ). Specifically, Figure 5a This demonstrates how to process the geometric model of a 3D object (especially by slicing) to generate slice data containing 2D images (slices) of the 3D object, each 2D image corresponding to the cross-sectional geometry of the 3D object, and then use these slice data to print the 3D object by multicolor photopolymerization, especially two-color photopolymerization.

[0187] Figure 5b This illustrates the same process when modifying a model of a 3D object. The modification is based on... Figure 5a The principle of changing at least one parameter of the geometric model of the shown 3D object is achieved, as described above, by altering information about the 3D object model to be manufactured in the CAD file (especially the STL file). Therefore, in Figure 5b In this process, the modified geometric model of a three-dimensional object is processed, particularly by slicing, to generate slice data containing two-dimensional images (slices) of the three-dimensional object. Each two-dimensional image corresponds to the cross-sectional geometry of the three-dimensional object. Then, using these slice data, the three-dimensional object is printed out through multi-color light aggregation, especially two-color light aggregation.

[0188] Figure 5c The same process is illustrated when using a further modified 3D object model. This modification follows the steps described above, altering the information about the 3D object model to be manufactured in the CAD file (specifically the STL file). Figure 5b The principle is based on at least one parameter of the modified geometric model of the shown three-dimensional object. Therefore, in Figure 5c In the process, the geometric model of the further modified three-dimensional object is processed, especially by slicing, to generate slice data containing two-dimensional images (slices) of the three-dimensional object. Each two-dimensional image corresponds to the cross-sectional geometry of the three-dimensional object. Then, using these slice data, the three-dimensional object is printed out through multi-color light aggregation, especially two-color light aggregation.

[0189] therefore, Figure 5a – Figure 5c The principle shown can involve multiple iterations, each of which involves changing at least one parameter of the geometry of the 3D object to be printed.

[0190] In either case, the method, particularly when it involves multicolor light polymerization, especially two-color light polymerization, as described above, may include a data processing step in which an image corresponding to the cross-sectional geometry of the three-dimensional object, or a plurality of points or lines corresponding to the cross-sectional geometry of the three-dimensional object, can be directly generated by data processing of a geometric model of at least one three-dimensional object; additionally or alternatively, the method may also include a data processing step (which can also be regarded as a reverse data processing step) in which a geometric model of at least one three-dimensional object can be directly generated by data processing of one or more images corresponding to the cross-sectional geometry of the three-dimensional object, or a plurality of points or lines corresponding to the cross-sectional geometry of the three-dimensional object.

[0191] As described above, the first data processing step may, for example, include slicing the geometric model of at least one 3D object into multiple slices with specific geometric shapes (especially specific thicknesses) using a slicing algorithm or slicing software; the second data processing step may, for example, include combining corresponding images, points, and lines corresponding to the cross-sectional geometry of the 3D object using a geometric model reconstruction algorithm or geometric model reconstruction software, thereby reconstructing the geometric model of at least one 3D object. Both the first and second data processing steps can be implemented efficiently. For example, in the first data processing step, the corresponding slices can be obtained directly from the geometric model of the 3D object to be manufactured, while in the second data processing step, the corresponding geometric model can be obtained directly from the corresponding slices of the 3D object. These two data processing steps also allow any modifications to the geometric model of the 3D object (e.g., CAD files or models, or STL files or models) to be effectively modified in relatively few steps, especially compared to volumetric printing methods that involve computational axial lithography (CAL) or similar volumetric printing processes.

Claims

1. A method for manufacturing three-dimensional objects by volumetric printing, the method comprising the following steps: a) Perform a volumetric printing process to manufacture a three-dimensional object based on data containing geometric model information of the three-dimensional object to be manufactured, wherein the volumetric printing process includes at least one irradiation process, the at least one irradiation process including irradiating a photocurable resin with light of a first wavelength and light of a second wavelength different from the first wavelength to form the three-dimensional object in at least one direction by multicolor photopolymerization, particularly by two-color photopolymerization, wherein the volumetric printing process is performed based on multiple process parameters; b) Determine at least one attribute of the three-dimensional object and generate determination information indicating at least one determined attribute of the three-dimensional object; c) Compare at least one determined attribute of the three-dimensional object with at least one reference attribute of a reference three-dimensional object, and generate comparison information indicating the comparison result, wherein the reference object is in particular the target three-dimensional object, and the reference attribute is in particular the target attribute; d) Determine whether the comparison result indicates that the deviation between at least one determined attribute of the three-dimensional object and at least one reference attribute of the reference three-dimensional object exceeds a threshold; and When the comparison result indicates that the deviation between at least one determined attribute of the three-dimensional object and at least one reference attribute of the reference three-dimensional object exceeds a threshold, at least one of the following shall be changed: at least one parameter of the geometric model of the three-dimensional object to be manufactured, at least one process parameter of the volume printing process, and at least one process parameter of the post-processing process. e) Using at least one modified parameter of the geometric model of the three-dimensional object to be manufactured and / or at least one modified process parameter of the volumetric printing process and / or at least one modified process parameter of the post-processing process, repeat steps a) to d) until the comparison results indicate that the deviation between at least one determined attribute of the three-dimensional object and at least one reference attribute of the reference three-dimensional object no longer exceeds the threshold.

2. The method according to claim 1, wherein, Determine at least one property of the three-dimensional object and generate determination information indicating at least one determined property of the three-dimensional object, including determining at least one chemical property and / or physical property of the three-dimensional object.

3. The method according to claim 2, wherein, At least one chemical property is or includes the chemical composition of the three-dimensional object, the chemical reaction state of the three-dimensional object, and in particular the polymerization state of the three-dimensional object.

4. The method according to claim 2, wherein, At least one physical property is or includes at least one of the following: acoustic properties, optical properties, geometric properties, mechanical properties, surface properties, electrical properties, thermal properties, and magnetic properties of a three-dimensional object.

5. The method according to claim 1, wherein, At least one determined property of the three-dimensional object indicates the deformation of the three-dimensional object relative to the reference three-dimensional object.

6. The method according to claim 1, wherein, A measuring device is used to determine at least one property of the three-dimensional object, the measuring device being configured to measure at least one chemical and / or physical property of the three-dimensional object.

7. The method according to claim 1, wherein, Changing at least one parameter of the geometric model of the three-dimensional object to be manufactured includes changing information about the CAD file, particularly the STL file, of the three-dimensional object model to be manufactured.

8. The method according to claim 6, wherein, Change at least one image parameter of the model of the three-dimensional object to be manufactured, in particular at least one pixel, voxel, or vertex.

9. The method according to claim 1, wherein, Changing at least one process parameter of the volume printing process includes changing at least one of the following: at least one parameter of the irradiation process in which the photocurable resin is irradiated within the working volume, such as irradiation time, irradiation intensity, and wavelength of the irradiation light. Printing speed; Printing direction; orientation of the three-dimensional object within the working volume; motion path along which the working volume moves during irradiation; at least one parameter of the photocurable resin used for volumetric printing of the three-dimensional object; at least one parameter for transferring the three-dimensional object, for example, at least one parameter for transferring the three-dimensional object from the volumetric printing device to the post-processing device.

10. The method according to claim 1, wherein, Changing at least one process parameter of the post-processing includes changing at least one of the following: post-processing time, post-processing intensity.

11. The method according to claim 1, wherein, Step b) is performed by a determining device and / or by a testing device, wherein the determining device is particularly an optical determining device, and more particularly a scanner, microscope, or profilometer, and the testing device is configured to test at least one property of the three-dimensional object according to the intended application and / or intended function of the three-dimensional object.

12. The method according to claim 1, wherein, Step c) is executed by a controller, particularly by a comparison algorithm of the controller, the controller being configured to compare at least one determined attribute of the three-dimensional object with at least one reference attribute of a reference three-dimensional object, and generate comparison information indicating the comparison result, wherein the reference three-dimensional object is particularly the target three-dimensional object, and the reference attribute is particularly the target attribute.

13. A system for manufacturing three-dimensional objects by volumetric printing, the system comprising: A volumetric printing apparatus for performing a volumetric printing process to manufacture a three-dimensional object based on data containing geometric model information of the three-dimensional object to be manufactured, wherein the volumetric printing process includes at least one irradiation process, the irradiation process including irradiating a photocurable resin with light of a first wavelength and light of a second wavelength different from the first wavelength to form a three-dimensional object in at least one direction by multicolor photopolymerization, especially dual-color photopolymerization, wherein the volumetric printing process is performed based on multiple process parameters; A determining device for determining at least one attribute of the three-dimensional object and generating determining information indicating at least one determined attribute of the three-dimensional object; A controller is configured to compare at least one determined attribute of the three-dimensional object with at least one reference attribute of a reference three-dimensional object and generate comparison information indicating the comparison result, wherein the reference object is, in particular, a target three-dimensional object, and the reference attribute is, in particular, a target attribute. The controller is configured to perform the following steps: Determine whether the comparison result indicates that the deviation between at least one determined attribute of the 3D object and at least one reference attribute of the reference 3D object exceeds a threshold; and If the comparison results indicate that the deviation between at least one determined attribute of the three-dimensional object and at least one reference attribute of the reference three-dimensional object exceeds the threshold, then at least one of the following is changed: at least one parameter of the geometric model of the three-dimensional object to be manufactured, at least one process parameter of the volume printing process, and at least one process parameter of the post-processing process.

14. A computer program product comprising instructions for causing a controller of the system of claim 13 to perform at least the steps of the method of claim 1.

Images