Methods and systems for forming three-dimensional objects

Abstract

Methods and systems of forming three-dimensional objects are disclosed. A method can include providing a volume of photoresponsive resin contained within an optically transparent resin container; simultaneously directing a plurality of optical projections from an optical subsystem arranged on a side of the resin container through a sidewall of the optically transparent resin container and through the volume of photoresponsive resin at a plurality of angles θ, the plurality of optical projections also being directed about a z-axis extending through the volume of photoresponsive resin; and providing a calculated three-dimensional intensity distribution for each of the plurality of optical projections that acts over a fixed temporal exposure period to form a desired 3D part, and wherein the operation of simultaneously directing the plurality of optical projections from the optical subsystem at the plurality of angles θ includes, for each of the plurality of angles θ, stacking a plurality of one-dimensional image slices along the z-axis to form a two-dimensional image, and generating a simultaneous superposition of the plurality of two-dimensional optical projections for each of the angles θ to generate a 3D intensity function in space.

Description

[0001] This application is a divisional application of National Application No. 201880042822.2, International Application Date March 27, 2018, National Entry Date December 25, 2019, entitled "System and Method for Computer Axial Lithography (CAL) for 3D Additive Manufacturing".

[0002] Cross-reference to related applications

[0003] This application is a PCT international application, U.S. Patent Application No. 15 / 593,947, filed May 12, 2017. The entire disclosure of the above application is incorporated herein by reference.

[0004] Government Rights Statement

[0005] The United States government has rights to this invention under contract number DE-AC52-07NA27344 between the U.S. Department of Energy and Lawrence Livermore National Security, LLC, concerning the operation of Lawrence Livermore National Laboratory. Technical Field

[0006] This disclosure relates to systems and methods for performing additive manufacturing, and more specifically to systems and methods for volumetric fabrication using computed tomography (CT) technology. Background Technology

[0007] This section provides background information relating to this disclosure, which is not necessarily prior art.

[0008] Additive manufacturing (AM) methods are rapidly evolving, with photopolymer-based methods among the most prominent. These stereolithography techniques offer a useful balance between resolution, build speed, processing control, and cost. However, these system metrics often require trade-offs. Addressing speed limitations, surface roughness (stair-step artifacts), and requirements for support structures will provide the next major steps for the advancement of these technologies.

[0009] With the rise and versatility of additive manufacturing (AM) technology, a constraint on almost every AM method is its reliance on continuously repeating low-dimensional unit operations, building structures voxel-by-voxel or layer-by-layer. This can be an advantage, providing significant processing flexibility, but it is often a disadvantage, causing limitations in dimensionality and surface finish; for example, it is impossible to produce smooth, curved geometries. Several methods have demonstrated the ability to generate 3D structures without the need for planar slicing, notably the fabrication of lattices via lattice beams at Hughes Research Laboratory. see TASchaedler et al., “Ultralight Metallic Microlattices”, Science, Vol. 334, No. 6058, pp. 962-965, November 2011) and photonic crystals produced by interference lithography ( see Y. Lin, A. Harb, K. Lozano, D. Xu, and K. PChen, “Five beam holographic lithography for simultaneous fabrication of three-dimensional photonic crystal templates and line defects using phase-tunable diffuse-active optical element,” Opt. Express, Vol. 17, No. 19, p. 16625, September 2009. However, these methods are limited to periodic structures, where one dimension is significantly smaller than the other two. Even Carbon3D’s “continuous” liquid interface treatment ( see (JRTumbleston et al., “Continuous liquid interface production of 3D objects”, Science, Vol. 347, No. 6228, pp. 1349-1352, March 2015) still require sequential manufacturing based on 2D discretization.

[0010] There is great anticipation for expanding the AM technology foundation to include fabrication via 3D unit operations, which generate 3D shapes with arbitrary geometries (“volume at once”). Such approaches are still in their infancy: the first “volume at once” fabrication based on photopolymers was recently demonstrated, as described in “Additive Fabrication of 3D Structures by Holographic Lithography” by M. Shusteff et al., Proceedings of the 26th Annual International Solid Freeform Fabrication Symposium, Austin, TX, 2016, pp. 1183–1192. This method utilizes a holographic light field generated by a pure phase liquid crystal on silicon (LCoS) spatial light modulator (SLM). The geometries achievable by the method of Shusteff et al. are limited by the constant cross-section along each of the three orthogonal directions. This limitation is primarily caused by the small diffraction angles achievable with existing SLMs due to their relatively large pixel sizes (minimum around 4μm, but more typically 8μm or larger). Summary of the Invention

[0011] This section provides a general overview of this disclosure, but is not a full and complete disclosure of its entire scope or features.

[0012] In one aspect, this disclosure relates to a method for forming a three-dimensional (3D) object. The method may include: providing a volume of photo-curable resin contained within an optically transparent resin container, and simultaneously guiding optical projections from an optical subsystem through the photo-curable resin at multiple angles θ. The optical projections may also be guided about a z-axis extending through the photo-curable resin. A calculated three-dimensional intensity distribution effective over a fixed temporal exposure period may be provided for each of the optical projections. During the fixed time period of providing projections from one or more angles, a net exposure dose is sufficient to cure selected portions of the photo-curable resin, leaving other portions uncured to form the desired 3D part.

[0013] In another aspect, this disclosure relates to a method for forming a three-dimensional (3D) object by providing a photocurable resin body housed within an optically transparent resin container. The z-axis extends through the photocurable resin body, and the r-axis extends perpendicularly to the z-axis. The resin container can be rotated about the z-axis while sequentially guiding optical projections in the x' direction from a stationary optical subsystem to the optically transparent resin container at different angles θ relative to the z-axis. A two-dimensional (2D) projection function of the optical projections can be controlled at each angle θ. This projection function can deliver a controlled 3D exposure dose. A total net 3D exposure dose can be generated within the resin body over a fixed temporary exposure period including projections from multiple angles θ. The total 3D exposure dose is sufficient to induce photocuring in desired areas without inducing photocuring in undesirable areas.

[0014] In another aspect, this disclosure relates to a method for forming a three-dimensional (3D) object. The method may include: providing a photocurable resin body contained within an optically transparent resin container, the z-axis extending through the photocurable resin body and the x'-axis extending perpendicularly to the z-axis. The method may further include using an optical subsystem to generate an optical two-dimensional (2D) projection function that generates a 3D intensity map. The method may further include: while maintaining the optical 2D projection being guided through the photocurable resin body, causing at least one of the 2D projections or the resin container to rotate relative to the other to receive the optical 2D projection around the complete periphery of the photocurable resin body. The two-dimensional (2D) projection function of the 2D projections may be controlled at each angle θ to deliver a controlled 3D projection dose over a fixed temporary exposure period, and wherein a plurality of 2D projections are generated from a plurality of angles θ. The plurality of 2D projections may be summed to generate a 3D exposure dose in the resin body sufficient to induce photocuring in a desired region but insufficient to induce photocuring in an undesired region.

[0015] In another aspect, this disclosure relates to a method for forming a three-dimensional (3D) object. The method may include providing a photocurable resin body housed within an optically transparent resin container, and simultaneously guiding optical projections from an optical subsystem through the photocurable resin body at multiple angles θ. The light beams are guided about a z-axis extending through the photocurable resin body. A calculated 2D spatial intensity function is provided for each of the projections to create a 3D intensity map. The projections operate within a fixed temporary exposure period during which a net exposure dose is sufficient to cure selected portions of the photocurable resin body while leaving other portions uncured to form the desired 3D part.

[0016] Other areas of application will become apparent from the description provided herein. The descriptions and specific examples in this invention are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0017] The accompanying drawings described herein are for illustrative purposes only, and not for all possible implementations, and are not intended to limit the scope of this disclosure.

[0018] Figure 1A Several diagrams are shown, providing an overview of the fundamental mathematical relationships used for the computational design of optical projections. These optical projections can be physically generated through various embodiments of this disclosure to create a target intensity distribution.

[0019] Figure 1B to Figure 1D The coordinate system used in this disclosure is shown to aid in describing various embodiments;

[0020] Figure 2A This illustration shows one embodiment of a system according to the present disclosure, which utilizes a system of lenses or other optics and light sources arranged circumferentially around a target resin volume to simultaneously generate projections at each angle θ. A 3D intensity map derived from all projections is simultaneously superimposed on a selected portion for curing the resin in a single operating step.

[0021] Figure 2B Show Figure 2A The 3D representation of the implementation method in which various optical projections pass through the target resin body at different angles θ;

[0022] Figure 3 A high-level diagram of another embodiment of this disclosure is shown, wherein a target resin container is rotated by a rotating support or pedestal, while an optical projection generating component provides a single projection at fixed intervals. This projection creates a 3D intensity field within the volume. The projection is updated as the resin body rotates over time and the angle θ changes.

[0023] Figure 4 A high-level diagram of another embodiment of this disclosure is shown, wherein the target resin container remains stationary and the rotating arm assembly guides the optical projection from a varying angle θ.

[0024] Throughout the various views of the accompanying drawings, corresponding reference numerals indicate the respective components. Detailed Implementation

[0025] The exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0026] The method described in this invention disclosure achieves bulk fabrication by applying computed tomography (CT) technology in reverse, i.e., by exposing a photopolymer resin body to 3D light fields from multiple angles and updating the light fields at each angle. The necessary light fields are multiplexed spatially and / or temporally such that their total energy dose in the target resin body crosslinks the resin into a user-defined geometry. These light fields can be static or dynamic and can be generated by any suitable mechanism, such as a spatial light modulator (SLM). The SLM controls the phase or amplitude of the light fields, or possibly both, to provide the necessary intensity distribution. The light fields at each angle θ can be generated simultaneously or sequentially in time. In the case of sequential generation, the light fields can be generated in any order. This disclosure significantly enhances the processing possibilities in the art, providing means to generate a 3D radiation dose distribution within a given bulk, enabling the realization of virtually arbitrary structures through photopolymer curing.

[0027] This disclosure is based on the spatial and / or temporal multiplexing of a three-dimensional (3D) optical field associated with a photosensitive resin bath volume. Multiplexing can be implemented in many ways, including, but not limited to, those described in the specific embodiments and methods described in the following paragraphs. Multiplexing can be implemented by delivering a controlled exposure dose to selected areas of the resin to in-situ cure a user-designed 3D geometry within a photopolymer construct.

[0028] Conceptually, the teachings of this disclosure are built upon the well-developed field of computed tomography (CT). CT typically refers to imaging a 3D volume from multiple angles, most commonly by using X-rays to penetrate the volume, where each image is generated sequentially by irradiation from directions arranged in azimuth. The 3D volume is then reconstructed using various known computational techniques. Such known computational techniques can include Fourier domain methods such as filtered back projection (FBP) or optimization-based iterative techniques. see For example, SWSmith, “The Scientist & Engineer’s Guide to Digital Signal Processing,” First Edition, San Diego, California: California Technical Pub, 1997. Utilizing CT methods useful for capturing and recording 3D geometry information, computed axial lithography (CAL) inverts the concept to generate 3D geometry based on exposure of photopolymers from multiple angles. The implementation described herein retains the “one-step” capability while significantly improving upon three-beam holographic lithography methods (Shusteff et al.). ibid. The geometric flexibility of the ) eliminates the conventional discretization “ladder” product.

[0029] For cancer treatment purposes, CT optimization has been used to deliver intensity-modulated radiotherapy (IMRT), which delivers a targeted 3D distribution of radiation dose to a specific area within a patient's organ while minimizing the dose in non-target areas. re ference For example, T. Bortfeld, J. Bürkelbach, R. Boesecke, and W. Schlegel, “Methods of image reconstruction from projections applied to conformation radiotherapy,” Phys. Med. Biol, Vol. 35, No. 10, pp. 1423–1434, October 1990. The constraints of 3D lithography fabrication are generally less stringent, suggesting that photosensitive resins can be crosslinked using a similarly specified 3D dose distribution of radiation.

[0030] Tomographic image calculation

[0031] To understand the relationship between the geometry of the target 3D part and the calculated projection, consider Figure 1A as well as Figure 1B to Figure 1D The coordinate system is specified in the table. For the following discussion, it is convenient to use a global Cartesian coordinate system (x, y, z) to refer to the 3D construct and to consider a rotated Cartesian coordinate system (x', y', z') whose orientation depends on the angle θ of the projection. In these coordinate systems, z is the axis used to align the exposures at angle θ around the volume 10. For each angle θ, the projection is calculated. At a specific angle θ, the projection is defined as a two-dimensional function P. θ (y',z), this two-dimensional function completely determines the three-dimensional intensity map I generated in the target volume. θ (x,y,z)(Note: P) θ Depending on the angle θ, but because it has two spatial dimensions, it is called a two-dimensional function. In its simplest case, the projection can be considered as a two-dimensional image propagating through the (y',z) domain of the resin body in the x' direction. In this ideal case, the 3D intensity distribution generated by the projection looks like an image in the (y',z) domain protruding through the target body in the x' direction. This approximation remains physically good if the projection is collimated. In medical imaging applications, this is equivalent to parallel-beam computed tomography. For this disclosure, this is a sufficiently good approximation as long as the optical configuration has a long depth of focus (especially in relation to the small diffraction angles achievable with current SLM techniques). In general, the optical propagation and attenuation model describes the 3D intensity map generated at a specific angle according to the 2D projection function. In this specification and Figure 1AIn order to simplify the description of the method, we consider an idealized case.

[0032] The goal of tomographic image computation is to design a set P(y',z,θ) of 2D projected images from a series of angles θ such that the 3D intensity map generated by superimposing the 3D light fields generated from each projection approximates or exactly approximates the target 3D intensity map. Now, consider the design of the projections based on the known target 3D intensity map. To further simplify the explanation, the problem of generating a set of 2D projections for the 3D intensity map is reduced to the problem of generating a set of 1D projections P(y',θ) for the 2D intensity map I(x,y). Furthermore, in this case, 1D refers to a spatial dimension y'. In a physical (x,y,z) resin system, the 2D intensity map can be viewed as a horizontal, constant z-slice of the true 3D intensity map. Finally, the 2D projection P at a given angle θ can be generated by stacking each of the calculated 1D projections in each z-plane. θ (y',z).

[0033] Among the many ways to reconstruct CT images, two main methods that facilitate dose optimization for fabrication are filtered back projection (FBP) and optimization-based iterative algorithms. Here, we first consider the FBP method and its limitations, and describe how it can be used to provide useful starting parameters for optimization algorithms.

[0034] The FBP method for reconstructing the 2D optical density distribution in the (x,y) plane for a given value z begins with M angle samples (θ = θ1, θ2, ... θ). M At each point in the ), a mathematical 1D projection is calculated. These acquired projections together comprise the Radon transform of the 2D image. According to the principle of projection slicing, as discussed in R. Bracewell, “Strip Integration in Radio Astronomy,” Aust. J. Phys., vol. 9, no. 2, p. 198, 1956, and R. Bracewell, “Numerical Transforms,” Science, vol. 248, no. 4956, pp. 697-704, May 1990, it is known that the Fourier transform of the 1D projection at each specific angle θ is exactly equal to a 1D sample of the Fourier transform of the original 2D density distribution. This 1D sample is positioned along a line passing through the origin in the Fourier domain and tilted at angle θ. This is in Figure 1AThe above is described in detail. Sufficiently dense sampling in the Fourier domain is required for accurate CT image reconstruction. To appropriately choose the number of samples M in the Fourier domain, a possible conventional heuristic is to ensure that the maximum distance between slices is no greater than the radial interval of N sampling points. This results in πN / 2 angular samples within a 180-degree angular range.

[0035] The photolithography fabrication of each 2D z-plane can follow the arithmetic-time reversal of CT imaging processing. This will be used for slice I. z The target 2D intensity map (x,y) is transformed to the Fourier domain, and then sampled along each of the M azimuth angles to generate M 1D intensity distributions or projections P. θ (y'), for each angle θ1,θ2,…θ M One. Each of these distributions is used to expose the target plane from its specific angle with its corresponding pattern, which corresponds to constructing samples from slices through the origin in the Fourier domain. The FBP used for CT reconstruction relies on high-pass spatial filtering prior to backprojection to mitigate the low-frequency oversampling inherent in the central slicing method. An equivalent described here would be a radially increasing ramp filter. This filter typically causes a negative offset in the lithographically unfavorable (unphysical) backprojected image. Some heuristics for eliminating negative values ​​and producing lithographically suitable images include imposing positive constraints or compensating for the calculated image. The results of such heuristics impose a trade-off between the contrast and resolution of the calculated dose distribution; however, they can be used as initial dose estimates for constrained optimization processes.

[0036] Briefly, the optimization process takes a forward processing model as its starting point, which correlates resin monomer crosslinking with the received light energy dose. Various 2D versions of such models are available, for example, as discussed in D. Dendukuri, P. Panda, R. Haghgooie, JMKim, T.A. Hatton, and P.S. Doyle, “Modeling of Oxygen-Inhibited Free Radical Photopolymerization in a PDMS Microfluidic Device,” Macromolecules, Vol. 41, No. 22, pp. 8547–8556, November 2008, where progress toward 3D simulation is limited. An error function is generated by comparing the modeled degree of curing (caused by the total dose distribution from all angles) with the desired part geometry; this error function is inversely transformed and used to modify the initial dose estimate. This loop is iterated multiple times to satisfy specific error criteria, such as edge sharpness, contrast, or the total error over the entire build volume. This optimization process provides a means to accurately model and account for processing nonlinearities such as intensity absorption in image generation. This is a significant advantage in terms of feature quality. The extension from the 2D plane to the 3D plane is direct, where, corresponding to a specific x' propagation direction, for each angle θ, the 1D intensity patterns from each z-plane are combined into a 2D y'-z image. Effectively, this is the physical projection of the calculated Radon transform for all z-planes at each angle θ to reconstruct the desired 3D dose.

[0037] One specific implementation of the method described above is Figure 2A The system 24 shown in the figure. System 24 may include a plurality of optical subsystems 26, which are arranged such that they generate angles θ1, θ2, ... θ around the target resin body 29 contained within the optically transparent container 29a at a particular selection of angles θ1, θ2, ... θ M The optical projection set P(y',z,θ) is generated at a specific location. One possible design for the optical subsystem 26 may include an OLED array 27 covered by microlenses 28 surrounding the 3D target resin body 29. The OLED array 27 may be partially controlled by the controller 26a. Different groups of the optical subsystem 26 simultaneously generate projections P through the target resin body 29 at different angles θ1, θ2, θ3, etc. θ (y',z) and the corresponding 3D intensity map I θ (x,y,z)261, 262, 263, etc., such as Figure 2B As shown. Projection P θ (y',z) and intensity map Iθ (x,y,z) is similar to the projection and intensity map described in paragraph

[0019] . Figure 2B The 2D nature of each of the optical projections 261, 262, and 263 is shown. Projections 261, 262, and 263 are simultaneously delivered from M (i.e., two or more) different angles θ around the z-axis to the target resin body 29 contained within the resin container 29a. Figure 2B ).like Figure 2A The 3D intensity fields 261, 262, 263 from all angles around the entire 360-degree periphery of the target resin body 29 are simultaneously superimposed in space to generate a 3D intensity function I(x,y,z). This intensity function operates within a fixed temporary exposure period. During exposure, the areas where material formation is desired receive a sufficient dose of light energy to cause solidification due to photocuring, while areas where formation (i.e., curing) is not desired receive an insufficient dose. After the exposure period, the resin container 29a can be rinsed to remove uncured resin from the areas of the 3D part that have received insufficient doses of light energy to achieve photocuring.

[0038] More basic information on light field photography and 3D displays can be found in Ng, R., “Digital LightField Photography (Doctoral dissertation, Stanford University)” and Lanman, D. and Luebke, D., “Near-eye light field displays” (ACM Transactions on Graphics (TOG)), vol. 32, no. 6, p. 220, which are incorporated herein by reference. This information relates to the possibility of creating the required optical subsystem from a microlens-covered LED array. System 24 thus forms a device for simultaneously generating images from multiple viewpoints and simultaneously exposing the entire target resin body 29 to projections 261, 262, 263 from each angle θ. Because each projection 261, 262, 263 acts on the body simultaneously, the final 3D part can be printed in a single step.

[0039] By performing the printing in a single step and avoiding sequential layer-by-layer printing, some potential problems in existing AM methods can be addressed. These problems include difficulties in printing overhanging geometries and avoiding layered products with poor surface finish and mechanical anisotropy. An additional benefit of this method is that the constructed structure does not move relative to the fluid medium, enabling the fabrication (in conjunction with suitable rinsing / drying methods, such as solvent displacement followed by supercritical CO2 drying) of very flexible or fragile components, such as low-volume-fragment hydrogel scaffolds.

[0040] refer to Figure 3 The system 30 is illustrated as follows: a 3D exposure dose distribution is generated at fixed time intervals by a physical rotation of a target resin body 32 about a z-axis 42, which is synchronized via a controller 31 with the time manipulation of a single 2D optical projection from a digital light processing (DLP) projector or other image generation optics system 34. In the implementation described earlier herein, the image generation optics system 34 generates a collimated optical image or projection 36 illuminating the target resin body 32 from a single direction along axis x'41. It will be understood that the image may also be somewhat divergent (i.e., not collimated) and the algorithm designed for it can be updated accordingly.

[0041] When different (y',z) plane images are projected sequentially, the relative angle θ between the incident light of projection 36 and the target resin body 32 changes over time. Following the previous... Figure 1B , Figure 1C and Figure 1D The coordinate system convention described and depicted in the text is such that, as the target resin body 32 rotates, the (x,y,z) system rotates about the z-axis while the (x',y',z) system remains fixed in space. Therefore, the angle θ between the x-axis and x'-axis changes as the target resin body 32 rotates. In one example, the resin container 38 holding the target resin body 32 is mounted on a rotating support or platform. The rotating support rotates about the z-axis 42, and the operation of the DLP projector 34 is synchronized with the rotation of the support 40 via a controller 31. The container 38 can be immersed in a second container 44 containing a fluid 46 having the same (or similar) refractive index as the resin 32. This provides a flat interface where the refractive index changes and mitigates the lensing effect that may occur at curved interfaces with mismatched refractive indices. Note that in the description of the above system, the coordinate notation makes the x'-axis stationary while the (x,y,z) coordinate system rotates with the resin container 38.

[0042] Figure 3 Another embodiment of the system 30 shown may involve using multiple DLP projectors 34 (i.e., multiple optical subsystems) positioned facing each of the four vertical walls of the second receiving vessel 44 to generate multiple optical 2D projections. Yet another embodiment may involve... Figure 3 The system 30 shown is modified in that, while the DLP projector 34 (i.e., the optical subsystem) rotates around the entire outer periphery of the container 38 on the annular support 34, both the container 38 and the second container 44 remain stationary to generate multiple optical 2D projections.

[0043] Figure 3Another variation of the embodiments shown may involve using photodegradable (e.g., photoresponsive) materials instead of resin. For example, a desired 3D part can be produced by starting with a solid 3D block of photodegradable material and using optical 2D projection as described herein to remove only certain portions of the solid 3D block. Such materials are used, for example, in tissue engineering.

[0044] refer to Figure 4 The diagram illustrates a system 50 according to another embodiment of the present disclosure. In system 50, a resin body 52 is housed in a stationary container 54. A second container 55 may be used to hold an additional amount of fluid 55a having the same (or similar) refractive index as the resin body 52. ​​An optical subsystem 56 generates an optical projection 58 along an x-axis (fixed relative to the stationary target body). A 3D intensity map generated by the projection is rotated about the resin body 52 via a rotating arm assembly 50a (i.e., about the z-axis 60 and propagated along the rotating x'-axis 61). A stationary mirror 62 receives the projection 58 and feeds it to an assembly of mirrors 64 to 68 housed within the rotating arm assembly 50a. Mirrors 64 to 68 guide the projection 58 to illuminate the resin body. As the arm rotates, a y'-z-plane image is projected around the entire periphery at a number of angles θ. As in other embodiments, the net exposure dose from the sum of the 3D intensity distributions generated from all projections from a single rotation ensures that the areas where the desired material is formed receive a sufficient dose to photocrosslink the resin, while other areas receive an insufficient dose. Figure 2A to Figure 2B The method described is similar, for example, using a spatial light modulator (SLM) 70 or a DLP projector, controlling the spatial and temporal modulation of the projection at each angle θ (i.e., modulation of the image intensity of the projected 2D (y'-z) image). Combined with... Figure 3 Compared to the described method, system 50 allows for potentially faster rotational speeds by eliminating considerations of fluid motion. (Combined with...) Figure 2A to Figure 2B Compared to the methods described, System 50 offers the advantage of a simpler optical system based on existing technologies. Figure 4 The proposed configuration shown can be applied to one or more simultaneously rotating optical projections. (Combined with...) Figure 2A and Figure 2B The method described is similar, and the resin container 54 does not move relative to the fluid during manufacturing, thus allowing for the formation of more fragile, brittle, or flexible structures.

[0045] Finally, optical signal multiplexing required for implementing computer-aided axial lithography can be performed by a system that shares features of any or all of the embodiments described above. As an example, a light field projection display that does not project across a full 360° angle ( Figure 2A to Figure 2B It can be similar to Figure 3The system 30 uses a combination of rotating bottles to extend the angular range. For example, consider using, for instance, rotating bottles... Figure 2A and Figure 2B The curved display shown instead has a cylindrical shape, resembling a semi-cylinder or a smaller angled portion of a cylinder. It still projects images from multiple angles simultaneously, but the angular range spans less than 360 degrees (180 degrees in the case of a semi-cylinder). However, if the display rotates around the resin body and the projection is updated in real time, it could potentially span a full 360 degrees, or even more. Figure 4 The implementation shown is likely to be faster. Such an implementation may not be as fast to print as the implementation in Figure 2, but it may be easier to manufacture. Similarly, the target body can remain fixed in the case where a <360-degree projection display rotates around the resin target body.

[0046] The systems and methods disclosed herein surpass recently reported methods for fabricating aperiodic volumetric three-dimensional (3D) structures using holographic light fields in terms of geometric flexibility. Similarly, the inherently volume-based approach of this disclosure offers an order of magnitude improvement in fabrication speed compared to conventional layer-by-layer “2 1 / 2D” printing techniques. Finally, the surface roughness issues associated with layer-by-layer fabrication are significantly reduced without complete removal.

[0047] The systems and methods of this disclosure are expected to be applicable to a wide range of applications. For example, the systems and methods of this disclosure provide improvements to photopolymer-based additive manufacturing in many important ways, such as faster part generation, improved surface quality (e.g., no “staircase” products from layering), and reduced geometric constraints caused by 2D layer slicing, as well as simplified post-processing. Potential applications of the various embodiments and methods described herein may involve AM-generated optical elements with high-quality surface finishes; hollow or overhanging structures; large dynamic range mesoscale AM ​​structures; printing / manufacturing of pre-fabricated 3D structures immersed in resin; and processing soft, flexible, or fragile polymers and geometrically brittle / fragile structures (due to the lack of relative structural / fluid movement during printing).

[0048] For example, this disclosure may also include the following technical solutions:

[0049] Technical Solution 1. A method for forming a three-dimensional (3D) object, comprising:

[0050] Provides a photoresponsive resin body housed within an optically transparent resin container;

[0051] Simultaneously, optical projections from the optical subsystem are guided through the photoresponsive resin body at multiple angles θ, and the optical projections are also guided around a z-axis extending through the photoresponsive resin body; and

[0052] Each of the optical projections is provided with a calculated three-dimensional intensity distribution that operates within a fixed temporary exposure period, sufficient to cure or remove at least one of selected portions of the photoresponsive resin body, while leaving the other portions unmodified to form the desired 3D part.

[0053] Technical Solution 2. The method according to Technical Solution 1, wherein the operation of simultaneously guiding the optical projection from the optical subsystem at multiple angles θ includes simultaneously superimposing the optical projections to generate a 3D intensity function in space.

[0054] Technical Solution 3. The method according to Technical Solution 1, wherein the calculation design of the optical projection delivered from the optical subsystem at multiple angles θ includes:

[0055] For each of a plurality of z-planes extending through the z-axis, a one-dimensional (1D) intensity pattern for a specific z-plane is generated at each angle θ; and

[0056] For each z-plane, the 1D intensity patterns for a specific angle θ are combined into a two-dimensional (2D) image projection from that angle θ, and this operation is performed for each angle θ.

[0057] Technical Solution 4. The method according to Technical Solution 1, wherein the computational design of the optical projection delivered from the optical subsystem at multiple angles θ includes:

[0058] Fourier domain methods are used, including at least one of filtered back projection (FBP) techniques or optimization-based iterative techniques.

[0059] Technical Solution 5. The method according to Technical Solution 1 further includes: after the fixed temporary exposure period, rinsing the resin container to remove uncured resin from the area of ​​the photocured 3D component.

[0060] Technical Solution 6. The method according to Technical Solution 1, wherein the operation of simultaneously guiding optical projections from an optical subsystem at multiple angles θ includes: generating the optical projections from a microlens array and a plurality of organic light-emitting diodes (OLEDs) arranged around the periphery of the target resin body, wherein each projection from a specific angle θ is generated from a specific subset of OLEDs.

[0061] Technical Solution 7. The method according to Technical Solution 6 further includes using a controller to control the OLED array.

[0062] Technical Solution 8. A method for forming a three-dimensional (3D) object, comprising:

[0063] Provides a photocurable resin body contained within an optically transparent resin container, with the z-axis extending through the photocurable resin body and the x' axis extending perpendicularly to the z-axis;

[0064] Rotate the optically transparent resin container about the z-axis, and simultaneously, as the resin body rotates, guide the optical projections from the stationary optical subsystem in a fixed x' direction to the resin container sequentially along different angles θ relative to the resin body coordinate system (x, y, z); and

[0065] Specifically, a two-dimensional (2D) projection function of the optical projection is controlled at each angle θ to deliver a controlled 3D exposure dose.

[0066] During a fixed temporary exposure period, which includes projections from multiple angles θ to produce a total 3D exposure dose in the resin body, the total 3D exposure dose is sufficient to induce photocuring in the desired area without inducing photocuring in the undesired area.

[0067] Technical Solution 9. The method according to Technical Solution 8 further includes: arranging the optically transparent resin container inside a second container, wherein the second container is filled with a fluid having a refractive index matching that of the resin.

[0068] Technical Solution 10. The method according to Technical Solution 8, wherein rotating the optically transparent container includes: fixing the optically transparent container to a rotating support stage and using the rotation state to rotate the optically transparent container.

[0069] Technical Solution 11. The method according to Technical Solution 8, wherein the rotation of the optically transparent container is synchronized with the optical projection via a controller.

[0070] Technical Solution 12. The method according to Technical Solution 8, wherein guiding the optical projection from the stationary optical subsystem includes: guiding the optical projection from the stationary digital light processing (DLP) projector.

[0071] Technical Solution 13. The method according to Technical Solution 8, wherein guiding the optical projection from a stationary optical subsystem comprises: using a spatial light modulator (SLM) to generate the optical projection, the spatial light modulator (SLM) controlling the amplitude or phase, or both amplitude and phase, of the incident light source.

[0072] Technical Solution 14. The method according to Technical Solution 8 further includes: after the fixed temporary exposure period, rinsing the resin container to remove uncured resin from the area of ​​the photocured 3D part.

[0073] Technical Solution 15. The method according to Technical Solution 8, wherein the computational design of the optical projection delivered from the optical subsystem at multiple angles θ includes:

[0074] For each of a plurality of z-planes extending through the z-axis, a one-dimensional (1D) intensity pattern for a specific z-plane is generated at each angle θ; and

[0075] For each z-plane, the 1D intensity patterns for a specific angle θ are combined into a two-dimensional (2D) image projection from that angle θ, and the generation and combination operations are performed for each angle θ.

[0076] Technical Solution 16. The method according to Technical Solution 8, wherein the computational design of the optical projection delivered from the optical subsystem at multiple angles θ includes:

[0077] Fourier domain methods can be used, including filtered back projection (FBP) techniques, optimization-based iterative techniques, or both filtered back projection (FBP) techniques and optimization-based iterative techniques.

[0078] Technical Solution 17. A method for forming a three-dimensional (3D) object, comprising:

[0079] Provides a photocurable resin body contained within an optically transparent resin container, with the z-axis extending through the photocurable resin body and the x' axis extending perpendicularly to the z-axis;

[0080] An optical subsystem is used to generate an optical two-dimensional (2D) projection;

[0081] While maintaining the optical 2D projection guided through the photocurable resin body, at least one of the 2D projection or the resin container is rotated relative to the other to receive the optical 2D projection around the complete periphery of the photocurable resin body; and

[0082] Wherein, a two-dimensional (2D) projection function of the 2D projection is controlled at each angle θ to deliver a controlled 3D exposure dose within a fixed temporary exposure period, wherein a plurality of 2D projections are generated from a plurality of angles θ, and wherein the plurality of 2D projections are summed to generate a 3D exposure dose in the resin body, the 3D exposure dose being sufficient to induce photocuring in the desired region but insufficient to induce photocuring in the undesired region.

[0083] Technical Solution 18. The method according to Technical Solution 17, wherein moving at least one of the 2D projection or the resin container relative to the other comprises: using a rotating arm assembly having a plurality of mirrors configured to guide the optical 2D projection toward the photocurable resin body while both the resin container and the optical subsystem remain stationary.

[0084] Technical Solution 19. The method according to Technical Solution 17, wherein moving at least one of the 2D projection or the resin container relative to the other comprises: using a rotating arm assembly having a plurality of mirrors configured to guide the optical 2D projection toward the photocurable resin body while the resin container is also rotating.

[0085] Technical Solution 20. The method according to Technical Solution 17, wherein using the rotating arm assembly includes: using the rotating arm assembly to receive the optical 2D projection from a stationary mirror.

[0086] Technical Solution 21. The method according to Technical Solution 17, wherein guiding the 2D projection from the optical subsystem includes: guiding the optical 2D projection from a stationary digital light processing (DLP) projector.

[0087] Technical Solution 22. The method according to Technical Solution 17, wherein guiding the optical 2D projection from the optical subsystem comprises: using a spatial light modulator (SLM) to guide the optical 2D projection from the stationary optical subsystem, the spatial light modulator (SLM) controlling the amplitude or phase, or both amplitude and phase, of the incident light source.

[0088] Technical Solution 23. The method according to Technical Solution 17 further includes: arranging the resin container inside a second container, the second container containing a fluid having a refractive index matching that of the resin.

[0089] Technical Solution 24. The method according to Technical Solution 17, wherein moving at least one of the 2D projection or the resin container relative to the other comprises: while the resin container remains stationary, rotating the optical subsystem circumferentially around the resin container to guide the optical 2D projection toward the photocurable resin body from the plurality of angles.

[0090] Technical Solution 25. The method according to Technical Solution 17, wherein the computational design of the optical 2D projection delivered from the optical subsystem at multiple angles θ includes:

[0091] For each of a plurality of z-planes extending through the z-axis, a one-dimensional (1D) intensity pattern for a specific z-plane is generated at each angle θ; and

[0092] For each z-plane, the 1D intensity patterns for a specific angle θ are combined into a two-dimensional (2D) image projection from the specific angle θ, and the generation and combination operations are repeated for each angle θ.

[0093] The foregoing description of the embodiments provided is for illustrative and descriptive purposes. It is not intended to be exhaustive or limiting of this disclosure. Various elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable where applicable and can be used in the chosen embodiment, even if not specifically shown or described. Embodiments may also vary in many ways. Such variations should not be considered as departing from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A method for forming a three-dimensional (3D) object, comprising: Provides a photocurable resin body contained within an optically transparent resin container, with the z-axis extending through the photocurable resin body and the x' axis extending perpendicularly to the z-axis; as well as The optically transparent resin container is rotated about the z-axis, and simultaneously, as the resin body rotates, multiple optical projections from a stationary optical subsystem arranged on the side of the optically transparent resin container in a fixed x' direction are guided sequentially to the resin container along different angles θ relative to the resin body coordinate system (x,y,z), such that the multiple optical projections pass through the side wall portion of the optically transparent resin container. Specifically, at each angle θ, a two-dimensional (2D) projection function of the optical projection is controlled to deliver a controlled 3D exposure dose. During a fixed temporary exposure period, which includes multiple projections from multiple angles θ to produce a total 3D exposure dose in the resin body, the total 3D exposure dose is sufficient to induce photocuring in the desired area without inducing photocuring in the undesired area.

2. The method according to claim 1, wherein, Rotating the optically transparent resin container includes: fixing the optically transparent resin container to a rotating support and using the rotating support to rotate the optically transparent resin container.

3. The method according to claim 1, wherein, The rotation of the optically transparent resin container is synchronized with the plurality of optical projections via a controller.

4. The method according to claim 1, wherein, The guidance of multiple optical projections from a stationary optical subsystem includes: guiding multiple optical projections from a stationary digital light processing (DLP) projector.

5. The method according to claim 1, wherein, Guiding multiple optical projections from a stationary optical subsystem includes using a spatial light modulator (SLM) to generate multiple optical projections, the SLM controlling the amplitude or phase, or both, of the multiple optical projections.

6. The method according to claim 1, further comprising: After the fixed temporary exposure period, the resin container is rinsed to remove uncured resin from the areas of the photocured 3D part.

7. The method according to claim 1, wherein, The computational design for delivering multiple optical projections from the optical subsystem at multiple angles θ includes: For each of a plurality of z-planes extending through the z-axis, generate a one-dimensional intensity pattern for a specific z-plane at each angle θ; and For each z-plane, the one-dimensional intensity patterns for a specific angle θ are combined into a two-dimensional (2D) image projection from that angle θ, and the generation and combination operations are performed for each angle θ.

8. The method according to claim 1, wherein, The computational design for delivering multiple optical projections from the optical subsystem at multiple angles θ includes: Fourier domain methods can be used, including filtered back projection (FBP) techniques, optimization-based iterative techniques, or both filtered back projection techniques and optimization-based iterative techniques.

9. A method for forming a three-dimensional (3D) object, comprising: Provides a photocurable resin body contained within an optically transparent resin container, with the z-axis extending through the photocurable resin body and the x' axis extending perpendicularly to the z-axis; Use an optical subsystem to generate an optical two-dimensional projection; as well as This causes at least one of the optical two-dimensional projection or the optically transparent resin container to move relative to the other, so that the optically transparent resin container receives the optical two-dimensional projection. Wherein, a two-dimensional projection function of the optical two-dimensional projection is controlled at each angle θ to deliver a controlled 3D exposure dose within a fixed temporary exposure period, wherein multiple two-dimensional projections are generated from multiple angles θ, and wherein the multiple two-dimensional projections are summed to generate a 3D exposure dose in the resin body, the 3D exposure dose being sufficient to induce photocuring in the desired region but insufficient to induce photocuring in the undesired region.

10. The method according to claim 9, wherein, Moving at least one of the optical two-dimensional projection or the resin container relative to the other includes using a rotating arm assembly having a plurality of mirrors configured to guide the optical two-dimensional projection toward the photocurable resin body while both the resin container and the optical subsystem remain stationary.

11. The method according to claim 9, wherein, Moving at least one of the optical two-dimensional projection or the resin container relative to the other includes using a rotating arm assembly having a plurality of mirrors configured to guide the optical two-dimensional projection toward the photocurable resin body while the resin container is also rotating.

12. The method according to claim 9, wherein, Using the rotating arm assembly includes: using the rotating arm assembly to receive the optical two-dimensional projection from a stationary mirror.

13. The method according to claim 9, wherein, Guiding two-dimensional projections from the optical subsystem includes guiding optical two-dimensional projections from a stationary digital light processing (DLP) projector.

14. The method according to claim 9, wherein, Guiding an optical two-dimensional projection from an optical subsystem includes: using a spatial light modulator (SLM) to guide the optical two-dimensional projection from a stationary optical subsystem, wherein the spatial light modulator controls the amplitude or phase, or both, of the optical two-dimensional projection.

15. The method according to claim 9, wherein, Moving at least one of the optical two-dimensional projection or the resin container relative to the other includes: while the resin container remains stationary, rotating the optical subsystem circumferentially around the resin container to guide the optical two-dimensional projection toward the photocurable resin body from the plurality of angles.

16. The method according to claim 9, wherein, The computational design for delivering two-dimensional optical projections from the optical subsystem at multiple angles θ includes: For each of a plurality of z-planes extending through the z-axis, generate a one-dimensional intensity pattern for a specific z-plane at each angle θ; and For each z-plane, the one-dimensional intensity patterns for a specific angle θ are combined into a two-dimensional image projection from the specific angle θ, and the generation and combination operations are repeated for each angle θ.

17. The method according to claim 9, wherein, The optical subsystem uses a Fourier domain method, including at least one of filtered back-projection techniques or optimization-based iterative techniques, to deliver the multiple two-dimensional projections at multiple angles θ.

18. A system for forming a three-dimensional (3D) object from a photoresponsive material volume contained within a material container, the system comprising: Controller; Support, the support being used to support the material container; as well as An optical projection subsystem, controlled by the controller, is used to generate multiple two-dimensional optical projections, each of which is guided at the material container. Specifically, a two-dimensional projection function controls the two-dimensional optical projection at each angle θ to deliver a controlled 3D exposure dose. Wherein, at least one of the optical projection subsystem or the support moves at multiple different angles θ relative to the photoresponsive material body contained within the material container to provide a total 3D exposure dose, such that multiple two-dimensional optical projections are guided from the optical projection subsystem into the photoresponsive material body, thereby causing at least selected portions of the photoresponsive material to undergo photopolymerization.

19. The system according to claim 18, wherein, The optical projection subsystem includes a digital light processing (DLP) projector.

20. The system according to claim 18, wherein, The two-dimensional optical projection generated by the optical projection subsystem includes a nearly collimated two-dimensional optical image.

21. The system according to claim 18, wherein, The optical projection subsystem includes multiple optical projection subsystems arranged at different angles around the photoresponsive material body.

22. The system according to claim 18, wherein, The optical projection subsystem and the photoresponsive material body rotate simultaneously.

23. The system of claim 18, further comprising: The material container, wherein the material container includes an optically transparent material container.

24. The system according to claim 18, wherein, The optical projection subsystem includes a spatial light modulator.

25. The system according to claim 18, wherein, The controller controls the two-dimensional optical projection generated at multiple angles θ through the following operations: For each of the multiple z-planes extending through the z-axis, generate a one-dimensional intensity pattern for a specific z-plane at each angle θ; as well as For each z-plane, the one-dimensional intensity patterns for a specific angle θ are combined into a two-dimensional image projection from that angle θ, and this operation is performed for each angle θ.

26. The system according to claim 18, wherein, The controller is configured to use a Fourier domain method, including at least one of filtered back projection (FBP) or an optimized iterative technique, such that the optical projection subsystem delivers the two-dimensional optical projection at multiple angles θ.

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