Volume 3D printing optical element manufacturing method based on multi-dimensional spin-coating surface modification

Abstract

The invention provides a volume 3D printing optical element manufacturing method based on multi-dimensional spin-coating surface modification, which comprises the following steps: preparing a photosensitive resin precursor solution containing a low-concentration photoinitiator, and performing exposure molding through a volume 3D printing technology to obtain a semi-cured initial blank; preparing a spin-coating liquid containing a high-concentration photoinitiator and an optional functional additive, and coating the surface of the primary blank with the spin-coating liquid through a precise spin-coating process; and finally, light curing is performed in a vacuum environment, so that the liquid film is completely crosslinked and chemically bonded with the surface of the initial blank. The high-concentration initiator spin-coating layer is used for overcoming the oxygen inhibition effect, a traditional solvent cleaning process is replaced, and the Ralt is obtained; the high-smoothness optical surface with the thickness of 5 nm is obtained, the original geometric accuracy of printing is kept, meanwhile, spin coating liquid is used as a universal carrier, full-color coloring, gradient color and multi-layer function superposition of the surface of an optical element are achieved, and the application range of volume printing in the optical field is greatly expanded.

Description

Technical Field

[0001] The invention relates to the field of 3D printing technology, and in particular to a method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification. Background Technology

[0002] Volumetric 3D printing, such as computational axial lithography (CAL) or tomographic volumetric printing, can solidify an entire three-dimensional object in a single pass within seconds to minutes by projecting dynamic light patterns from multiple angles onto a rotating resin container. To ensure that the excitation beam penetrates the entire resin tank and converges at the center, avoiding unnecessary over-curing, the photosensitive resin precursor used in volumetric printing must typically contain extremely low concentrations of photoinitiator (usually less than 0.1 wt%).

[0003] However, this low initiator concentration process leads to significant surface quality issues. Because oxygen in the air has a strong free radical quenching effect (i.e., oxygen inhibition), and the free radicals generated by the low concentration of initiator in the precursor solution are insufficient to counteract the oxygen inhibition on the surface, the printed preform surface is always coated with a layer of incompletely cured, sticky monomers. Existing post-processing methods typically use solvents such as ethanol or isopropanol to remove this uncured layer. However, for high-precision optical lenses, solvent cleaning can damage the surface's microscopic smoothness, leading to surface fogging, whitening, or texture defects (i.e., increased Ra value), severely affecting the imaging quality and transmittance of the optical lens.

[0004] Furthermore, existing volumetric printing technologies are typically limited to single-material manufacturing. Adding pigments directly to the printing resin results in the pigments absorbing or scattering light, severely limiting printing thickness and precision. Therefore, it is difficult to achieve personalized coloring, gradient color aesthetics, or composite functions (such as simultaneous blue light protection and scratch resistance) on the component surface without altering the transparency of the base material. This limits the application of this technology in consumer-grade eyewear, filters, and other fields.

[0005] Therefore, we propose a volumetric 3D printing method for manufacturing optical components based on multidimensional spin coating surface modification.

[0006] Application content Therefore, it is necessary to address the technical problems of incomplete curing and surface quality degradation caused by oxygen inhibition on the surface of existing volumetric 3D printed optical components, as well as the difficulty in achieving surface functionalization while maintaining the transparency of the bulk material. A method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification should be provided to achieve high surface smoothness of the optical components, while realizing full-color coloring, regional gradient coloring, and multi-layer superposition functionalization, which will greatly expand the application scope of volumetric printing in the optical field.

[0007] This application provides a method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification. The method includes preparing a photosensitive resin precursor solution containing a low concentration of photoinitiator, exposing it using volumetric lithography to obtain a semi-cured preform; preparing a spin coating solution containing a high concentration of photoinitiator and optional functional additives; coating the preform surface with the spin coating solution using a precision spin coating process; and finally, post-curing under light. This method effectively overcomes the surface stickiness and incomplete curing problems caused by oxygen inhibition in volumetric printing by utilizing a high-concentration initiator spin coating layer. It replaces the traditional solvent cleaning process, achieving a high-gloss optical surface while using the spin coating solution as a universal carrier, thus solving the technical challenge of achieving surface functionalization while maintaining bulk transparency in volumetric printing.

[0008] In other embodiments, the mass fraction of the photoinitiator in the first photosensitive resin precursor solution is 0.01%~0.1%, and the mass fraction of the photoinitiator in the second photosensitive resin spin-coating solution is 1.0%~6.0%, with concentration b > concentration a. By reasonably setting the concentration of the photoinitiator in the two photosensitive resins, it is ensured that the spin-coating layer can provide sufficient free radicals to overcome oxygen inhibition during the subsequent spin-coating and photocuring processes of the semi-cured preform, allowing the surface to fully cure and obtain a high-quality optical surface.

[0009] In other embodiments, the second photosensitive resin spin-coating solution further contains 0.05% to 5.0% by mass of a functional coloring component. The functional coloring component is selected from one or more of organic dyes, pigment pastes, photochromic materials, or spectral absorbers that can dissolve or disperse in the resin matrix. By changing the type of coloring component, a film layer with a specific color or filtering function is formed on the surface of the optical element. This makes it possible to achieve personalized coloring and specific functions on the surface of optical elements, meeting the needs of different application scenarios for the surface properties of optical elements.

[0010] In other embodiments, the precision spin coating process includes a low-speed spreading stage and a high-speed spin coating stage; the low-speed spreading stage has a rotation speed of 300~1000 rpm and a duration of 5~15 seconds; the high-speed spin coating stage has a rotation speed of 1500~6000 rpm and a duration of 20~60 seconds. By setting appropriate low-speed spreading and high-speed spin coating parameters, the spin coating liquid can be uniformly coated on the surface of the semi-cured preform, forming a liquid film of uniform thickness, ensuring the consistency of the surface quality of the optical components after subsequent photocuring.

[0011] In other embodiments, the same acrylate resin was used as the matrix, the photoinitiator concentration was significantly increased to 4.0 wt%, and 0.2 wt% leveling agent was added to reduce surface tension. The preform was fixed on a vacuum chuck spin coater, and first, it was rotated at 500 rpm for 10 seconds for low-speed wetting to allow the resin liquid to cover the surface. Then, it was linearly accelerated to 3000 rpm and held for 30 seconds for high-speed spin coating, using centrifugal force to control the liquid film thickness to 10-15 micrometers. The detailed and specific spin coating process parameter settings further optimized the spin coating process, ensuring precise and controllable liquid film thickness, which is beneficial for obtaining high-quality optical component surfaces.

[0012] In other embodiments, a dynamic multi-point droplet application and centrifugal diffusion process is employed to achieve a gradient color effect. Specifically, during spin coating, different colors or concentrations of spin coating liquid are dropleted onto different areas of the semi-cured preform. Centrifugal force drives the different fluids to mix and spread gradient across the surface, resulting in an optical element with a radially gradient color after curing. This process provides an effective method for preparing optical elements with gradient color effects, enriching the aesthetic appeal of optical elements and meeting market demands for personalized optical products.

[0013] In other embodiments, during the spin-coating preparation stage, two different spin-coating solutions are prepared: one is a pure, transparent, high-concentration initiator resin; the other is a dark-colored resin with added colorant. During the spin-coating process, the spin coater is first started at a low speed of 300 rpm. Using a dual-needle dispensing system, one needle is aimed at the geometric center of the lens to dispense the pure, transparent, high-concentration initiator resin, while the other needle is aimed at the edge area of ​​the lens to dispense the dark-colored resin with added colorant. After dispensing, the speed is linearly accelerated to 2500 rpm and maintained for 30 seconds. Centrifugal force is used to push the transparent liquid in the center outward, while the dark-colored liquid at the edge is stretched by shear force. The two undergo microscopic mixing and gradient diffusion in the middle area. By precisely controlling the spin-coating process and the dispensing position and method of different spin-coating solutions, a gradient color effect in a specific area on the surface of the optical element is achieved, providing a feasible technical solution for preparing optical elements with complex color distributions.

[0014] In other embodiments, steps S3 and S4 are repeated at least twice to achieve multi-layer functionalization. Specifically, after the first layer of spin coating liquid is applied and pre-cured, a second layer of spin coating liquid with different components or functions is spin-coated onto its surface, and then fully cured, thereby forming a multi-layer composite structure on the surface of the optical element. By repeating the spin coating and curing steps, multiple material layers with different functions can be integrated on the surface of the optical element, enabling the optical element to have multiple functions and meeting the requirements of different fields for the multifunctionality of optical elements. Attached Figure Description

[0015] Figure 1This is a process flow diagram of the manufacturing method described in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram comparing the microstructure of the optical lens surface prepared by the traditional solvent cleaning process and the spin coating process of this invention.

[0017] Figure 3 This is a schematic diagram of the cross-sectional structure of the color optical lens described in Embodiment 2 of the present invention.

[0018] Figure 4 This is a schematic diagram illustrating the process principle of achieving a gradient color effect using dynamic multi-point dripping as described in Embodiment 3 of the present invention.

[0019] Figure 5 This is a schematic diagram of the layered structure of the multifunctional superimposed composite lens described in Embodiment 4 of the present invention.

[0020] Among them, 10 is the lens layer; 20 is the spin coating layer; 21 is the first functional layer; 22 is the second functional layer; 30 is the central dripping needle; and 31 is the edge dripping needle. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0022] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0023] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0027] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation. (The definitions and explanations of these terms help clarify the spatial relationships and connection methods involved in the patent, avoiding ambiguity caused by unclear expressions. In practical applications, different component installation and connection methods affect the performance and function of the entire device. Clarifying these terms can provide an accurate basis for the subsequent description of the technical solution, ensuring that the scope of patent protection is clear and unambiguous.) This addresses the issues mentioned in the background section regarding incomplete curing and surface quality degradation caused by cleaning in existing volumetric 3D printed optical components. In traditional volumetric 3D printing, oxygen inhibits the action of photoinitiators, often resulting in incompletely cured optical component surfaces that appear sticky. Furthermore, solvent cleaning is typically used to remove these uncured residues, but this method can damage the component surface, increasing surface roughness and affecting the optical performance. Oxygen inhibition is a common problem in volumetric 3D printing, limiting the surface quality of printed products. While solvent cleaning can remove residues, it introduces new surface defects.

[0028] This patent proposes an innovative solution to these problems. By changing the printing process and material formulation, it fundamentally solves the issues of oxygen inhibition and cleaning damage, providing a new approach to improving the quality of volumetric 3D printed optical components. This manufacturing method combines the advantages of volumetric 3D printing and spin coating technologies. Volumetric 3D printing can rapidly produce optical component preforms with complex geometries, while spin coating technology can precisely modify the surface of the preform. By controlling the concentration of the photoinitiator and the spin coating process parameters, the surface properties of the optical components can be precisely controlled to meet the needs of different optical applications. This method provides an efficient, flexible, and high-quality solution for the manufacture of optical components.

[0029] This invention utilizes a high-concentration initiator spin coating to effectively overcome the surface stickiness and incomplete curing problems caused by oxygen inhibition in volumetric printing. It replaces the traditional solvent cleaning process, achieving a high-gloss optical surface while using the spin coating liquid as a universal carrier to realize full-color coloring, regional gradient coloring, and multi-layer functionalization of optical element surfaces. This solves the technical challenge of achieving surface functionalization while maintaining bulk transparency in volumetric printing. The high-concentration initiator spin coating provides sufficient photoinitiator, ensuring complete surface curing even in the presence of oxygen inhibition during the post-light curing process. This method, replacing solvent cleaning, not only avoids surface damage during cleaning but also simplifies the manufacturing process and improves production efficiency. Furthermore, the spin coating liquid, as a universal carrier, allows for the addition of various functional additives to meet different needs, enabling diversified functionalization of optical element surfaces and expanding the application areas of volumetric 3D printed optical elements.

[0030] Specifically, a method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification in this embodiment includes the following steps: S1. Prepare a first photosensitive resin precursor solution containing a photoinitiator of concentration 'a'; use volumetric 3D printing technology to expose and mold the first photosensitive resin precursor solution to obtain a semi-cured preform with the target geometry; the low concentration of photoinitiator in the first photosensitive resin precursor solution is to achieve preliminary curing during the volumetric 3D printing process, forming a semi-cured preform with a certain strength. Volumetric 3D printing technology can quickly and accurately manufacture optical components with complex shapes, providing a foundation for subsequent surface modification. The geometry of the semi-cured preform determines the shape of the final optical component; therefore, precise control of printing parameters is required to ensure the quality of the preform.

[0031] S2. Prepare a second photosensitive resin spin-coating solution, wherein the base resin is compatible with the first photosensitive resin precursor solution and contains a photoinitiator of concentration b, wherein the concentration b is significantly higher than the concentration a; The second photosensitive resin spin-coating solution also contains 0.05% to 5.0% by mass of a functional coloring component. This functional coloring component is selected from one or more of organic dyes, pigment pastes, photochromic materials, or spectral absorbers that can dissolve or disperse in the resin matrix. By changing the type of coloring component, a film layer with specific color or filtering function is formed on the surface of the optical element. The compatibility of the second photosensitive resin spin-coating solution with the first photosensitive resin precursor solution ensures that the spin-coating solution can be uniformly coated on the surface of the preform and has good adhesion to it. A high concentration of photoinitiator ensures complete surface curing during subsequent post-light curing. The added functional coloring component can be selected according to different needs to achieve coloring and functionalization of the optical element surface. For example, organic dyes can impart vibrant colors to the optical element, photochromic materials can make the color of the optical element change with light intensity, and spectral absorbers can be used to manufacture filters, etc.

[0032] S3. Fix the semi-cured preform onto the spin coating device, coat the second photosensitive resin spin coating liquid onto the surface of the preform, and form a uniform liquid film by rotation and centrifugation. The precision spin coating process described in step S3 includes a low-speed spreading stage and a high-speed spin coating stage; the rotation speed of the low-speed spreading stage is 300~1000 rpm, and the duration is 5~15 seconds; the rotation speed of the high-speed spin coating stage is 1500~6000 rpm, and the duration is 20~60 seconds.

[0033] Step S3 employs a dynamic multi-point drop-addition and centrifugal diffusion process to achieve a gradient color effect. Specifically, during spin coating, different colors or concentrations of spin coating liquid are dropped onto different areas of the semi-cured preform. Centrifugal force drives the different fluids to mix and spread gradients on the surface, resulting in an optical element with a radially gradient color after curing. The spin coating device's function is to uniformly coat the preform surface with the spin coating liquid. The low-speed spreading stage ensures the spin coating liquid fully wets the preform surface, preventing air bubbles and uneven distribution. The high-speed spin coating stage uses centrifugal force to remove excess spin coating liquid, forming a uniform liquid film. The dynamic multi-point drop-addition and centrifugal diffusion process is an innovative method for achieving a gradient color effect. By precisely controlling the drop position and the concentration of the spin coating liquid, centrifugal force is used to mix and spread different colored spin coating liquids on the surface, thus creating a natural gradient color effect. This process provides more possibilities for the appearance design of optical elements.

[0034] S4. The spin-coated preform is photocured in a vacuum environment to completely cross-link the liquid film and chemically bond it to the surface of the preform, thereby obtaining the target optical element.

[0035] In this embodiment, the mass fraction of photoinitiator in the first photosensitive resin precursor liquid is 0.01%~0.1%, and the mass fraction of photoinitiator in the second photosensitive resin spin coating liquid is 1.0%~6.0%.

[0036] Steps S3 and S4 are repeated at least twice to achieve multi-layer functionalization. Specifically, after the first layer of spin-coating liquid is applied and pre-cured, a second layer of spin-coating liquid with different components or functions is spin-coated onto its surface, followed by final complete curing, thereby forming a multi-layer composite structure on the surface of the optical element. Photocuring in a vacuum environment avoids the inhibitory effect of oxygen on the curing process, ensuring complete cross-linking of the liquid film and chemical bonding with the initial substrate surface, thus improving the surface quality and stability of the optical element. Repeating steps S3 and S4 enables multi-layer functionalization; each layer of spin-coating liquid can have different components and functions. By precisely controlling the thickness and curing degree of each layer, optical elements with complex functions can be manufactured. The multi-layer composite structure combines the advantages of different materials and functions to meet a wider range of optical application needs.

[0037] In the following examples, "basic spin-coating resin" refers to a photosensitive resin system that is compatible with the printing body resin and contains a high concentration (1%~6%) of photoinitiator; "compatible colorant" refers to an oil-soluble dye, pigment dispersion, or nano-color paste that can be stably dispersed or dissolved in the resin matrix.

[0038] Example 1 This embodiment aims to verify the feasibility of using a high-concentration initiator spin coating to replace solvent cleaning in the preparation of optical-grade surfaces for the fabrication of high-gloss transparent optical lenses.

[0039] First, the pre-printing solution was prepared and the substrate was molded. An acrylic resin pre-printing solution containing 0.05 wt% photoinitiator (such as CQ) was prepared and printed for 18 seconds using a 405nm volume printer under a light intensity of 15 mW / cm², yielding a transparent, semi-cured preform. At this stage, the sample was in a gel state, and the surface exhibited significant stickiness and stringiness due to oxygen inhibition. Direct cleaning would severely damage the surface quality.

[0040] The spin coating solution was then prepared and precision spin-coated. Using the same acrylic resin as the matrix, the photoinitiator concentration was significantly increased to 4.0 wt%, and 0.2 wt% leveling agent was added to reduce surface tension. The preform was fixed on a vacuum chuck spin coater, initially rotated at 500 rpm for 10 seconds for low-speed wetting to ensure the resin solution covered the surface; then linearly accelerated to 3000 rpm and held for 30 seconds for high-speed spin coating, using centrifugal force to control the film thickness to 10-15 micrometers.

[0041] Finally, post-curing was performed. The spin-coated sample was placed in a 365nm UV curing chamber (30mW / cm²) for 600 seconds in a vacuum environment. The results showed that the lens layer 10 surface was completely cured without any oxygen-inhibited adhesion. Figure 2 As shown, compared to the micropore defects present on traditionally cleaned surfaces, the surface treated in this embodiment has a smooth hardened film formed by a spin coating. As tested by a white light interferometer, the surface roughness Ra is less than 5nm and the light transmittance is greater than 92%, reaching the standard of a precision optical lens.

[0042] This embodiment successfully fabricated a high-gloss transparent optical lens by precisely controlling the photoinitiator concentration of the printing precursor solution, printing parameters, spin-coating solution formulation, and spin-coating process parameters. The high-concentration initiator spin-coating layer effectively overcame the oxygen inhibition problem and avoided surface damage caused by traditional solvent cleaning. The addition of a leveling agent reduced surface tension, which helped form a uniform liquid film. Post-curing under vacuum ensured complete surface curing and high quality. This fabrication method provides a new and efficient approach for manufacturing high-precision optical lenses and has broad application prospects.

[0043] Example 2 This embodiment is based on a color optical lens formulated with universal color paste. This embodiment verifies that spin coating liquid, as a universal carrier, can achieve the universality of surface coloring of the entire color system.

[0044] The printing steps are consistent with those in Example 1, and the lens is always made of a completely transparent material to avoid scattering interference from pigment particles on the volume printing light path and to ensure the geometric accuracy of the lens.

[0045] In the spin coating process, a general-purpose spin coating matrix is ​​first prepared using a low-viscosity modified resin (viscosity approximately 300 cp) and a high concentration of photoinitiator. Based on this matrix, three functional spin coating solutions are formulated by adding different types of general-purpose color pastes: 1. Formula A: Add an appropriate amount of yellow oil-soluble dye. This dye has a characteristic absorption peak in the 400-450nm wavelength range and forms an amber-colored filter film after curing.

[0046] 2. Formula B: Add an appropriate amount of black nano-pigment (or full-spectrum absorber). This pigment can uniformly reduce visible light transmittance and form a neutral gray shading film after curing.

[0047] 3. Formula C: Add an appropriate amount of red or blue organic pigment dispersion. This pigment imparts a vibrant color to the coating, forming a highly saturated decorative film after curing.

[0048] Considering the slight increase in viscosity after adding colorant, the spin coating process was adjusted to: low speed 800 rpm (10 seconds) for spreading, and high speed 2000 rpm (40 seconds) for film formation, to ensure a uniform film thickness of approximately 30 micrometers. After curing, the three types of lenses remained clear and transparent, with only a uniform transparent color layer formed on the surface. Figure 3 As shown, the component exhibits a clear "transparent core-colored shell" structure, successfully achieving a coloring effect similar to vacuum coating.

[0049] This embodiment demonstrates the versatility of spin-coating fluids as universal carriers in achieving full-color surface coloring. By selecting different universal color pastes, spin-coating fluids with different functions can be formulated to meet various optical requirements. The use of low-viscosity modified resins facilitates the uniform dispersion of the color paste and the formation of the liquid film. Adjusting the spin-coating process parameters can accommodate spin-coating fluids of different viscosities, ensuring the formation of a uniform film thickness. This coloring method is not only simple to operate but also achieves high-quality coloring results, providing more options for the personalized design of optical components.

[0050] Example 3 Decorative lenses with radial gradient effect: In this embodiment, a gradient lens with a transparent center and dark edges is prepared by using a fluid dynamics control process.

[0051] The printing process is the same as in Example 1, resulting in a transparent preform. During the spin coating preparation stage, two different spin coating solutions are prepared: Solution 1 is a pure, transparent, high-concentration initiator resin; Solution 2 is a dark-colored resin with added blue colorant.

[0052] A dynamic multi-point droplet application method is used during spin coating. For example... Figure 4 As shown, the spin coater is first started at a low speed of 300 rpm. Using a dual-needle dispensing system, the central dispensing needle 30 is aligned with the geometric center of the lens to dispense liquid 1, while the edge dispensing needle 31 is aligned with the edge region of the lens to dispense liquid 2. After dispensing, the speed is linearly increased to 2500 rpm and maintained for 30 seconds. During this process, centrifugal force pushes the central transparent liquid outward, while the edge dark liquid is stretched by shear force, resulting in microscopic mixing and gradient diffusion between the two in the middle region.

[0053] After being cured by light, the lens exhibits a natural gradient effect that smoothly transitions from colorless at the center to deep blue at the edges, without obvious dividing lines, verifying the ability of this method to achieve complex aesthetic effects using fluid dynamics control.

[0054] This embodiment successfully fabricated a decorative lens with a radial gradient color effect using a fluid dynamics control process. The dynamic multi-point droplet addition method precisely controls the droplet position and amount of different colored spin-coating liquids. Centrifugal force causes the liquids of different colors to mix and spread on the surface, forming a natural gradient color effect. This process eliminates the need for complex molds and additional processing steps, enabling the rapid and efficient manufacture of optical lenses with complex aesthetic effects, providing new ideas and methods for the design and manufacturing of optical products.

[0055] Example 4 This embodiment is used to manufacture a multifunctional composite structure lens. This embodiment achieves the physical superposition of different functions through a step-by-step spin coating process.

[0056] The printing process is the same as in Example 1. First, the first functional layer 21 (UV protective layer) is prepared: a transparent spin-coating solution containing a UV absorber is prepared and spin-coated at 3000 rpm for 30 seconds. Then, the crucial "pre-curing" step is performed, which involves irradiating the surface with weak UV light at 10 mW / cm² for 60 seconds. At this point, the surface has set and no longer flows, but some unreacted double bonds remain (the surface is slightly sticky), providing chemical sites for interlayer bonding.

[0057] Next, the second functional layer 22 (functional color layer) is prepared: a spin coating solution containing the second functional colorant is prepared and directly spin-coated onto the first pre-cured film at 3000 rpm. Finally, it is fully cured by irradiation with strong UV light (30 mW / cm²) for 60 seconds.

[0058] The final component structure is as follows Figure 5 As shown, a sandwich structure with "body-UV barrier layer-second functional layer" is used. This process can integrate material layers with different functions on the same component through multiple spin coatings.

[0059] This embodiment successfully fabricated a multifunctional composite lens using a step-by-step spin-coating process. The "pre-curing" step is crucial; it ensures the surface of the first functional layer is shaped while providing chemical sites for interlayer bonding, guaranteeing that the second functional layer adheres firmly to the first. Through multiple spin-coating processes, different functional material layers can be integrated onto the same element, achieving multifunctionality in optical components. This process provides an effective method for functional integration of optical components, meeting the needs of more complex optical applications.

[0060] In summary, the beneficial effects of the present invention are as follows: 1. Overcoming Oxygen Inhibition: By utilizing a high-concentration initiator spin coating, complete surface curing can be achieved through post-curing, resulting in an optical-grade surface with Ra < 5 nm. The high-concentration initiator spin coating provides sufficient photoinitiator to overcome the inhibitory effect of oxygen during post-curing under light irradiation, ensuring complete surface curing. This surface exhibits extremely low roughness, meeting the requirements of high-precision optical applications and guaranteeing the high-quality manufacturing of optical components.

[0061] 2. Avoids cleaning damage: This invention replaces the traditional solvent cleaning step, maintaining the original geometric accuracy of the print. Traditional solvent cleaning easily damages the surface of optical components, affecting their geometric accuracy and optical performance. The method of this invention avoids this problem, directly obtaining a high-quality surface through spin coating and post-curing processes, maintaining the original geometric accuracy of the print, and improving the reliability and stability of the optical components.

[0062] 3. Versatile Functionality: Using spin coating fluid as a universal carrier enables flexible full-color coloring, gradient colors, and multi-layer functional overlay, greatly expanding the application range of volumetric printing. As a universal carrier, spin coating fluid can be supplemented with various functional additives to achieve diversified functionalization of optical component surfaces. Full-color coloring, gradient colors, and multi-layer functional overlay can meet the optical application needs of different fields, such as optical instruments, lighting, and displays, opening new avenues for the application of volumetric 3D printing technology in the optical field.

[0063] The above description is an explanation of the invention, not a limitation thereof. The scope of the invention is defined in the claims. Within the scope of protection of the invention, any form of modification may be made.

Claims

1. A method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification, characterized in that, Includes the following steps: S1. Prepare the first photosensitive resin precursor solution: The first photosensitive resin precursor solution contains a photoinitiator at a concentration of a. S1.1 Exposure molding: The first photosensitive resin precursor liquid is exposed and molded using volumetric 3D printing technology to obtain a semi-cured preform with the target geometry. S2. Prepare the second photosensitive resin spin coating solution: The base resin of the second photosensitive resin spin coating solution is compatible with the first photosensitive resin precursor solution and contains a photoinitiator of concentration b. S3. Coating spin coating liquid: Fix the semi-cured preform onto the spin coating device, coat the second photosensitive resin spin coating liquid onto the surface of the preform, and form a uniform liquid film by rotation and centrifugation. S4. Photocuring: The spin-coated preform is photocured in a vacuum environment to completely cross-link the liquid film and chemically bond it to the surface of the preform, thereby obtaining the target optical element.

2. The method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification according to claim 1, characterized in that, In S1, the mass fraction of photoinitiator in the first photosensitive resin precursor solution is 0.01%~0.1%, and the mass fraction of photoinitiator in the second photosensitive resin spin coating solution is 1.0%~6.0%, and the concentration b > concentration a.

3. The method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification according to claim 1, characterized in that, In step S2, the second photosensitive resin spin coating liquid also contains 0.05% to 5.0% by mass of a functional coloring component. The functional coloring component is selected from one or more of organic dyes, pigment pastes, photochromic materials, or spectral absorbers that can be dissolved or dispersed in the resin matrix. By changing the type of the coloring component, a film layer with a specific color or filtering function is formed on the surface of the optical element.

4. The method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification according to claim 1, characterized in that, In S3, the precision spin coating process includes a low-speed spreading stage and a high-speed spin coating stage; the rotation speed of the low-speed spreading stage is 300~1000 rpm, and the duration is 5~15 seconds; the rotation speed of the high-speed spin coating stage is 1500~6000 rpm, and the duration is 20~60 seconds.

5. The method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification according to claim 4, characterized in that, In step S3, the same type of acrylate resin is used as the matrix, the concentration of photoinitiator is significantly increased to 4.0 wt%, and 0.2 wt% leveling agent is added to reduce surface tension. The preform is fixed on a vacuum chuck spin coater, and firstly, it is rotated at 500 rpm for 10 seconds for low-speed wetting to allow the resin liquid to cover the surface. Then, it is linearly accelerated to 3000 rpm and held for 30 seconds for high-speed spin coating, using centrifugal force to control the liquid film thickness to 10-15 micrometers.

6. The method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification according to claim 5, characterized in that, In S3, a dynamic multi-point dripping and centrifugal diffusion process is used to achieve a gradient color effect. Specifically, during the spin coating process, spin coating liquids of different colors or concentrations are dripped into different areas of the semi-cured blank. Centrifugal force is used to drive different fluids to perform gradient mixing and spreading on the surface. After curing, an optical element with radially gradient color is formed.

7. The method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification according to claim 6, characterized in that, In S3, during the spin coating preparation stage, two different spin coating solutions are prepared: one is a pure, transparent, high-concentration initiator resin; the other is a dark-colored resin with added colorant. During the spin coating process, the spin coater is first started at a low speed of 300 rpm. Using a dual-needle dispensing system, one needle is aimed at the geometric center of the lens to dispense the pure, transparent, high-concentration initiator resin, while the other needle is aimed at the edge area of ​​the lens to dispense the dark-colored resin with added colorant. After the dispensing is completed, the speed is linearly accelerated to 2500 rpm and maintained for 30 seconds. Centrifugal force is used to push the transparent liquid in the center outward, while the dark liquid at the edge is extended by shear force. The two undergo micro-mixing and gradient diffusion in the middle area.

8. The method for manufacturing volumetric 3D printed optical components based on multidimensional spin coating surface modification according to claim 1, characterized in that, Steps S3 and S4 are repeated at least twice to achieve multi-layer functionalization. Specifically, after the first layer of spin coating liquid is coated and pre-cured, a second layer of spin coating liquid with different components or functions is spin-coated on its surface and then fully cured, thereby forming a multi-layer composite structure on the surface of the optical element.

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