Solvent-free silsesquioxane for three-dimensional printing glass optics

Abstract

Example embodiments disclosed herein include a method of preparing a resin for three-dimensional (3D) printing of a glass component based on two-photon polymerization (TPP). The method comprises: forming a first mixture comprising a monomer, a first liquid, and a second liquid; using an F- catalyzation mechanism to form a resin, based on the first mixture and comprising silsesquioxane, that is fully hydrolyzed and condensed; and purifying the resin by filtering the product.

Description

SOLVENT-FREE SILSESQUIOXANE FOR THREE-DIMENSIONAL PRINTINGGLASS OPTICSSTATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0001] This invention was made with government support under Grant No. CA268190 awarded by National Institutes of Health. The government has certain rights in the invention.CROSS-REFERENCE TO RELATED APPLICATION

[0002] This patent document claims priority to and benefits of U.S. Provisional Application No 63 / 626,829, entitled “SOLVENT-FREE SILSESQUIOXANE FOR THREE-DIMENSIONAL PRINTING GLASS OPTICS,” and filed on January 30, 2024. The entire content of the above noted patent application is incorporated by reference as part of the disclosure of this patent document.TECHNICAL FIELD

[0003] This patent document is generally related to three-dimensional printing techniques.BACKGROUND

[0004] Three-dimensional (3D) printing of glass has demonstrated potential in diverse fields such as photonics, imaging, and microfluidics. Techniques for 3D printing glass components can lead to improvements in these fields.SUMMARY

[0005] The disclosed embodiments relate to a polymeric silsesquioxane (PSQ) resin for printing glass objects with high precision. The disclosed PSQ resin, among other beneficial features, exhibits reduced shrinkage and enhanced stability while retaining sinterless characteristics for high-resolution 3D printing of glass objects. The disclosed embodiments can be implemented to address the trade-offs between printing environment and high shrinkage of other materials, such as liquid silica resin (LSR) and polyhedral oligomeric silsesquioxane (POSS)-based materials.

[0006] Some disclosed embodiments leverage the two-photon polymerization (TPP) method to achieve nanostructures with feature sizes below 80 nm. Some disclosed techniques provide tunability of refractive index by incorporating zirconium moieties, which can facilitate thefabrication of glass micro-optics with varying refractive indices. Some advantages of the disclosed technology include self-welding capabilities which can be observed, for example, between two printed PSQ components. Such self-welding can provide a flexible approach for producing microoptics with multiple components, each possessing distinct refractive indices. The disclosed technology represents a significant advancement in the field of advanced precision glass manufacturing, paving the way for future applications in micro- and nano-scale glass optics.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1A shows a diagram of example structures of POSS molecules.

[0008] FIG. IB shows a diagram of an example scheme of synthesizing PSQ in accordance with implementations of the disclosed technology.

[0009] FIG. 1C shows a diagram of an example scheme of printing an inorganic glass in accordance with implementations of the disclosed technology.

[0010] FIGS. 2A-C show example experimental spectra of PSQ that can be obtained in accordance with implementations of the disclosed technology.

[0011] FIGS. 3A shows a diagram of example schemes to prepare a zirconium complex and a resin in accordance with implementations of the disclosed technology.

[0012] FIGS. 3B-G show example experimental data of samples treated with PSQ in accordance with implementations of the disclosed technology.

[0013] FIG. 4A shows a diagram of an example scheme of using different monomers to synthesize PSQ in accordance with implementations of the disclosed technology.

[0014] FIGS. 4B-C show example shrinkage data of samples treated with PSQ in accordance with implementations of the disclosed technology.

[0015] FIGS. 4D-E show example scanning electron microscopy (SEM) images of structures printed using PSQ resin obtained in accordance with implementations of the disclosed technology.

[0016] FIGS. 5A-G show example images of structures printed using PSQ in accordance with implementations of the disclosed technology.

[0017] FIG. 5H shows a diagram of an example instrumental scheme that can be implemented inaccordance with the disclosed embodiments.

[0018] FIG. 6A shows a schematic diagram of an example experimental setup and an example microscope image obtained using the experimental setup in accordance with implementations of the disclosed technology.

[0019] FIGS. 6B-D show example images obtained using the experimental setup of FIG. 6A.

[0020] FIG. 6E shows a schematic of a part of an optical system that can be fabricated in accordance with implementations of the disclosed technology.

[0021] FIG. 6F shows an example image captured using the optical system of FIG. 6E.

[0022] FIG. 6G shows a diagram of an example optical scheme that can be fabricated in accordance with implementations of the disclosed technology.

[0023] FIGS. 6H-I shows example images that can be captured using the optical scheme of FIG. 6G.

[0024] FIG. 7 shows example viscosity data of PSQ resins obtained in accordance with implementations of the disclosed technology.

[0025] FIG. 8 shows an example Raman spectrum of a PSQ resin obtained in accordance with implementations of the disclosed technology.

[0026] FIGS. 9A-B show example surface measurements of elements printed using two-photon polymerization in accordance with implementations of the disclosed technology.

[0027] FIG. 10A shows an example image of a structure printed in accordance with implementations of the disclosed technology.

[0028] FIGS. 10B-C show example images obtained using the structure of FIG. 10A.

[0029] FIG. 11 shows an example of the imaging performance of an optical structure printed in accordance with implementations of the disclosed technology.

[0030] FIG. 12A shows a diagram of an example self-welding scheme based on the disclosed technology.

[0031] FIG. 12B shows an example image captured using a structure printed in accordance with the self-welding scheme of FIG. 12A.

[0032] FIGS. 13 A shows an example image of three, separately printed structures after thermal treatment, where the printing of the structures and the treatment were performed in accordance with implementations of the disclosed technology

[0033] FIG. 13B shows an example image of a contacted region between two of the structures shown in FIG. 13 A.

[0034] FIG. 13C shows an example image of printed structures comprising different concentrations of zirconium in accordance with implementations of the disclosed technology.

[0035] FIG. 13D shows the structures of FIG. 13C after a thermal treatment performed in accordance with implementations of the disclosed technology.

[0036] FIGS. 14A-B show example nuclear magnetic resonance (NMR) spectra obtained in accordance with implementations of the disclosed technology.

[0037] FIGS. 15A-C show additional example NMR spectra obtained in accordance with implementations of the disclosed technology.

[0038] FIGS. 16A-B show example heteronuclear single quantum coherence (HSQC) spectra of a mixture obtained in accordance with implementations of the disclosed technology.

[0039] FIG. 17 shows an example heteronuclear multiple bond correlation (HMBC) spectrum of a mixture obtained in accordance with implementations of the disclosed technology.

[0040] FIGS. 18A-B show example homonuclear correlation spectroscopy (COSY) spectra of a mixture obtained in accordance with implementations of the disclosed technology.

[0041] FIGS. 19A-B show example comparisons of mixtures, obtained in accordance with implementations of the disclosed technology, before and after vacuum drying.

[0042] FIG. 20 shows a diagram of an example welding process based on the disclosed technology.

[0043] FIG. 21 shows a flow diagram of an example method based on the disclosed technology.

[0044] FIG. 22 shows a flow diagram of another example method based on the disclosed technology.

[0045] FIG. 23 shows a flow diagram of another example method based on the disclosedtechnology.DETAILED DESCRIPTION

[0046] Silica glass stands as one of the most valuable materials for a wide range of applications, including optics (having dimensions ranging, e g., from meters to micrometers), photonics, microfluidics, and insulation. Its outstanding optical transparency and high thermal and chemical resistance make it highly desirable. However, the high glass transition temperature (Tg) of silica glass (>1000°C) poses challenges in manufacturing objects with complex 2.5-dimensional (2.5D) or 3D structures. The need for feasible techniques to fabricate silica glass has spurred increasing attention on 3D printing of transparent glass in both academia and industry.

[0047] Various 3D printing techniques have been explored for manufacturing silica glass across dimensions ranging from meters to hundreds of nanometers. Among these techniques, photo-based printing methods, especially TPP, have consistently demonstrated superior printing resolution compared to other methods such as fused deposition manufacturing (FDM) and direct ink writing (DIW).

[0048] One widely used approach to achieve photo-printed silica glass is through the utilization of a particle-based resin, which involves a mixture of fumed silica nano-powder, photo-curable monomers, and crosslinkers. The resulting silica / polymer composite can be converted to transparent silica glass through a debinding-sintering process. This particle-based strategy offers several advantages, including easier printing of larger and thicker objects (in centimeters), nonsynthetic preparation, and high stability in a standard ambient environment during printing. However, it also has several limitations. First, it necessitates high-temperature treatment (1100 - 1300°C) due to the sintering step, and its printing resolution is constrained compared to molecular resin due to the size of the particles in the resin. Furthermore, the difference in refractive index (RI) between the silica particles and the organic resin can introduce challenges to the printing resolution, potentially causing scattering effects, which potentially restrict the applications in the high-precision optical field. Moreover, achieving the desired RI of glass manufactured through particle-based strategies is a nontrivial task. While powders with varying RIs can be developed, matching the RI between the powder and organic monomer (crosslinker) remains a significant challenge. To date, only pure silica with RI of -1.46 (uD20) has been successfully printed usingTPP methods.

[0049] In contrast, molecular level resin offers an alternative strategy for 3D printing glass without employing silica particles. Several studies have reported the use of photo-based molecular level organic / inorganic hybrid resins to print inorganic glass. Some techniques reported elsewhere involved the use of a solvent-free LSR to print glass obj ects through TPP, which were subsequently converted into transparent glass with optical properties nearly identical to fused silica glass at a low temperature of 600°C, although there was an additional 4% shrinkage when the glass objects were further heated to 1000°C. However, it has been observed that the remaining alkoxide (Si- OMe) group and silanol (Si-OH) group in the LSR make it sensitive to moisture in the air, leading to gelation within a few hours when printing is conducted under humidity levels exceeding 30%. This sensitivity to moisture restricts the printing time, with higher humidity accelerating the selfgelation process. One approach to address this water-sensitivity is to employ an organic / inorganic hybrid resin devoid of functional groups that are sensitive to water. A study performed elsewhere reported the use of a water-stable POSS combined with a photo-reactive acrylic oligomer solvent to print glass objects with a resolution of less than 100 nm. Additionally, this POSS-based resin enables full glass condensation at a mere 650°C. However, the glass objects manufactured using this POSS-based material exhibit relatively high shrinkage (-42% in the linear direction), which may limit manufacturing accuracy. Moreover, the effective adjustment of the RI of the final glass has not been conclusively demonstrated in the reported study.

[0050] The present patent document discloses example embodiments which provide an alternative approach by utilizing a solvent-free polymeric silsesquioxane (PSQ) for the 3D printing of inorganic glass through TPP. Some disclosed printed resins, with reduced organic content compared to previous POSS approaches, exhibit a reduced shrinkage of 32%. By optimizing the structure of the silsesquioxane with lower hydrocarbon concentrations, techniques disclosed herein can be implemented to further minimize the shrinkage. Additionally, the disclosed embodiments can be implemented to achieve linear tunability of the refractive index of the final glass by introducing zirconium moieties into the resin through a simple physical mixing. The high printing resolution achieved with the disclosed PSQ is exemplified, in one example, through the manufacturing of nanostructures with feature sizes below 80 nm. The disclosed embodiments can be used to fabricate glass micro-optics with varying refractive indices and high accuracy.

[0051] In an example study conducted in accordance with the disclosed embodiments, micro-imaging systems using printed glass micro-optics were assembled and evaluated, as will be discussed further in the description that follows. Moreover, due to the molecular structure similarity between PSQs with different refractive, glass micro-optics containing components with different refractive index were fabricated utilizing the disclosed self-welding process.

[0052] Example PSQ Synthesis and Shrinkage During Pyrolysis

[0053] To prepare a resin more stable than LSR, one approach is to replace all the TMOS with silanes that only contain three alkoxy groups. This substitution ensures that all the starting silane molecules have only three functional groups each, which can be hydrolyzed instead of four. When fully hydrolyzed and condensed with trimethoxy or triethoxy groups, the resulting molecule is a well-known compound known as silsesquioxane. Among the various types of silsesquioxanes, poly octahedral silsesquioxanes (POSS) are particularly renowned. FIG. 1A shows an example of typical structures of POSS molecules with different cage sizes. These cage-like molecules usually consist of 8, 10, or 12 silicon atoms forming a cubic structure.

[0054] One reported glass printing resin based on POSS (polyoctahedral silsesquioxane) exhibited a drawback with high shrinkage (-42%) after thermal treatment. This can be attributed to two main factors associated with the POSS-based material. Firstly, compared to a LSR material, the reported POSS-based material contains a higher concentration of methacrylate functional groups, resulting in a larger volume occupied by the organic component. Consequently, during the thermal treatment process, the removal of all crosslinked methacrylate chains leads to a considerable shrinkage in the material. Secondly, the highly ordered cage-like structure of POSS molecules causes them to be compactly stacked, resulting in the material having high viscosity. It is worth noting that the majority of POSS compounds exist in a solid state rather than a liquid state. To conduct the printing, 9% of liquid methacrylate monomer is mixed with POSS as a reactive solvent. Although this approach allows for 3D printing, it further increases the volume of the organic component, ultimately contributing to the final shrinkage issue.

[0055] To minimize shrinkage, a key approach is to reduce the viscosity of silsesquioxane without the need for additional monomers or solvents. In this regard, the utilization of the disclosed PSQ proves to be an ideal solution. FIG. IB shows an example scheme of synthesizing PSQ through a F- catalyze route. As shown therein, polymeric silsesquioxane (PSQ), unlike traditional POSS, is a mixture comprising a range of random ring-structured silsesquioxanes with varying molecular weights. These flexible rings, along with organic functional groups attached to them, act asspacers, resulting in a mixture with lower viscosity compared to POSS. In the example synthesis of PSQ, 3 -methacryloxypropyltri ethoxy silane (MPTES) was selected as the primary monomer. In some implementations, 3 -methacryloxypropyltrimethoxy silane,(Methacryloxymethyl)trimethoxysilane, (Methacryloxymethyl)triethoxysilane or a monomer comprising trialkoxy silane molecules that include one acrylate or methacrylate functional group may be selected. The synthesis process employs an F'catalyzed mechanism, enabling the formation of a fully hydrolyzed and condensed product within a short span of 2 hours. After removing all solvents used during the synthesis, the final product is a viscous oil, which presents no difficulties in dissolving photo-initiators without the need for any additional solvents. This advancement opens up possibilities for reducing shrinkage in the resulting material.

[0056] Before measuring the shrinkage of PSQ, thermogravimetric analysis (TGA) was conducted to gain a better understanding of the thermal behavior of UV-cured silsesquioxane and to optimize the thermal treatment procedure. It was observed that to achieve complete pyrolysis of the cured PSQ, a temperature higher than 600 °C (approximately 650 °C) is required. This temperature is similar to the one reported for printed POSS material but slightly higher than that of a previously reported LSR material, which only required 600 °C for complete pyrolysis. The reason for this difference lies in the higher ratio of methacrylate groups and the higher crosslinking density present in both the PSQ and POSS during UV curing. In the case of photocrosslinked acrylates, a higher crosslinking density typically contributes to enhanced thermal stability, leading to higher degradation temperatures.

[0057] FIG. 1C shows a scheme of an example procedure to print and obtain inorganic glass objects after thermal treatment. The example scanning electron microscopy (SEM) image in FIG. 1C shows a printed glass single lens (scale bar: 100pm).

[0058] To assess the shrinkage of the PSQ prepared using MPTES, a lens structure was fabricated via 3D printing and subjected to a thermal treatment at 650 °C. FIG. 2A shows an example Raman spectrum of as-printed PSQ. FIG. 2B shows an example Raman spectrum of thermally treated PSQ. FIG. 2C shows an example comparison of Fourier transform infrared (FTIR) spectra of fumed silica, thermally treated PSQ, and photo-cured PSQ. Both Raman (FIG. 2B) and FTIR (FIG. 2C) spectroscopy analyses revealed that the sample treated at 650 °C exhibited a chemical structure similar to fused silica. FIG. 3C shows the measured shrinkage at different temperatures during the thermal treatment. The dimensional change observed indicated that approximately 33% ofshrinkage occurred, which is nearly 10% less compared to the shrinkage observed in the case of POSS-based material. This notable reduction in shrinkage can be primarily attributed to the absence of organic monomers in the PSQ formulation.

[0059] To further reduce shrinkage, a second strategy can be adopted, which involves replacing the long methacryloxypropyl group with a shorter methacryloxymethyl group. It has been demonstrated elsewhere that shorter side chains in LSR resulted in lower shrinkage after thermal treatment, primarily due to the reduced organic volume. Building upon this knowledge, 3- methacryloxymethyltrimethoxysilane (MMTS) was utilized as the starting monomer to synthesize PSQ using the scheme, shown in FIG. 3A, of using of using different monomers (MPTES or MMTS) to synthesize PSQ.

[0060] FIG. 3B shows example TGA results of UV-cured PSQs. The curve of POSS was drawn using the data from literature. Thanks to the shorter organic side chain, the PSQ material exhibited an even lower shrinkage, measuring only 28.5%. This result aligns well with the TGA findings, as the PSQ-MMTS demonstrated 46.2% weight remaining after being subjected to 650 °C, which is 4.3% higher than the TGA results for PSQ-MPTES and 11.5% higher than the results for POSS- based material. Notably, the PSQ-MMTS tends to self-polymerize when it is placed at room temperature, which is not an obvious phenomenon for the PSQ-MPTES. Addition of inhibitor into the final resin helps suppress this self-polymerization process.

[0061] FIGS. 4D-E show example SEM images (scale bar: 200 pm) of glass triple lens microobjective printed using PSQ-MPTES (FIG. 4D) and PSQ-MMTS (FIG. 4E), respectively. These two objectives have slightly different structures with different dimensions.

[0062] The synthesized PSQ exhibits high stability to water when compared to LSR. The absence of methoxy or hydroxy groups in the final PSQ renders the material highly stable, allowing PSQ- MPTES to be stored at room temperature for at least one year without gelation. This stability makes the material inert to moisture in the air, enabling printing under various humidity conditions without the risk of self-gelation. In a typical printing scenario, no observable changes were noted in the material even after it was exposed to an ambient environment for a duration of 5 days.

[0063] Example Techniques to Reach Nano-scale Printing Resolution

[0064] To demonstrate an example of the printing resolution of PSQ resin in TPP 3D printing, a series of grid and grating structures with varying feature sizes were printed. FIGS. 5A-B showSEM images of an example micro-grid structure printed using PSQ. The printed micro-cubic grid structure is supported by a framework, featuring sharp edges and well-defined details. FIG. 5C shows an example microscopic image of the same grid as in FIGS. 5A-B. FIGS. 5D-F show example images of printed grating structures ranging from micrometers down to 75 nm, demonstrating that the disclosed resin can be used to achieve some of the highest printing resolutions observed in TPP printing. Notably, in FIG. 5E, the gap between each grating line measures approximately 430 nm and no merging of adjacent lines was observed, underscoring the high spatial printing resolution attained.

[0065] FIG. 5G shows a microscopic image of an example 3D printed grating array, printed using PSQ resin, with different feature sizes. FIG. 5G demonstrates the precise control which can be achieved, in accordance with the disclosed techniques, in printing nanometer-sized grating structures of a desired width. As shown in FIG. 5G, an array of gratings with varying line widths, from thin (left) to thick (right), was printed, and upon exposure to white light, different colors were observed due to the diffraction caused by varying line widths. Meanwhile, it is essential to mention that the light source we used was not parallel for all the grating structures, resulting in slightly different input angles for each grating cube, which, in turn, influenced the colors observed in the diffraction pattern. FIG. 5H show a schematic of the instrumental scheme of the example diffraction experiment.

[0066] Example Techniques to Change Refractive Index of PSQ and Final Glass

[0067] The remarkable stability of the disclosed PSQ resin enables tuning the RI of the final glass by introducing metal alkoxide molecules. It has been reported that the refractive index can be adjusted by chemically bonding zirconium alkoxide into a methacrylate-functionalized silsesqui oxane network through a sol-gel process, resulting in a 3D-printable ink capable of producing prints with tunable RI. However, the material obtained using this method requires the presence of solvents to maintain a liquid state and transform into a solid gel once all the solvent is removed. This feature necessitates a specialized coating and heating procedure for sample preparation, as well as a distinct printing setup, as the oil-immersed objective cannot be used with the solid film of the material. Moreover, writing directly in a solid film, rather than in a liquid, could potentially impact printing resolution and complicate post-printing development, making it more time-consuming.

[0068] To address these challenges, a solvent-free 3D-printable liquid resin with low viscosity is disclosed. The disclosed resin is also resistant to moisture and the zirconium alkoxides are stabilized by using methacrylic acid. Zirconium alkoxides are highly sensitive to water and tend to undergo hydrolysis upon contact. By binding carboxylic acids to the Zr core, the stability of zirconium alkoxides can be significantly improved. During this binding process, propyl methacrylate and 1 -propanol are generated as byproducts. The resulting Zr complex is then physically dissolved into the synthesized PSQ. Subsequently, propanol was removed under vacuum, while propyl methacrylate was retained due to its high boiling point. A scheme depicting the example preparation of the RI tunable resin using the Zr complex is shown in FIG. 6A. The zirconium complex is stabilized by methacrylic acid (MAA) and the resin is prepared for glass with different refractive index.

[0069] Due to the absence of chemical bonds between Zr and silsesquioxane, this material can maintain its liquid status. It should be noted that the concentration of zirconium moiety was kept below 10 mol%. Higher concentrations were found to lead to two major issues: an increase in ink viscosity and heightened sensitivity to moisture, making the ink more prone to gel formation in the air. FIG. 7 shows the example viscosity of PSO-MPTES and PSQ-MMTS. Only one data point of PSQ-MMTS was measured since the viscosity at higher shear rate is higher than the instrument’s limitation. It was observed that PSQ-MPTES proved to be a more suitable base material compared to PSQ-MMTS, mainly due to its lower viscosity. As a result, the Zr complex was exclusively mixed with PSQ-MPTES to achieve the desired refractive index tuning for the final glass.

[0070] The introduction of the Zr complex into the printing material brings the organic component methacrylic acid (MAA), contributing to the organic volume and increasing the shrinkage of the final glass. FIG. 3B shows example TGA results of UV-cured samples with different zirconium concentrations. FIG. 3C shows examples of the measured shrinkage of samples at different temperatures during the thermal treatment. As shown in FIG. 3B, the TGA measurements revealed that as the Zr concentration increased from 0% to 5%, 7.2%, and finally 10%, the remaining weight after thermal treatment decreased from 41.9% to 37.6%, 35.7%, and 33.3%, respectively. The samples containing the Zr complex exhibited a mass decrease at around 475 °C due to the decomposition of poly(methacrylic acid). The lower remaining weight indicates a reduced weight percentage of the final glass, leading to higher shrinkage after thermal treatment. As depicted inFIG. 3C, the gradual increase in Zr concentration up to 10% resulted in a final shrinkage of 41.5% at 650°C, which is approximately 8% higher than the pure PSQ-MPTES with about 33% shrinkage. In addition, a micro-Raman spectrum of PSQ-MPTES containing 7.2% Zr after thermal treatment is shown in FIG. 8. The spectrum was taken within the red circle region of FIG. 8. The Raman spectrum of the example printed sample after thermal treatment shows that there is no typical ZrCh crystal structure indicating the Zr is homogeneous dispersed before and after thermal treatment.

[0071] To measure the RI of final glass with different Zr concentration, thin films were prepared using PSQs on quartz, a thermal treatment was conducted, and measurements were obtained using an ellipsometer. Theoretically, the refractive index of a multi-component material can be roughly calculated using the equation showing below:[Equation 1] where ntheoreticairefers to the theoretical refractive index,refers to the refractive index of component i, and ctrefers to the mole concentration of component i in the whole material.

[0073] Using Equation 1, the theoretical nssonm for the final glass was calculated as 1.494, 1.509, and 1.529 when the zirconium concentration increased from 0% to 5 mol%, 7.2 mol%, and 10 mol%, respectively. FIGS. 3D-F present the measured nssonm of the thermally treated thin films with 5 mol%, 7.2 mol%, and 10 mol% of Zr, which were determined as 1.4692, 1.48222, and 1.52134, respectively. Although all measured values were slightly lower than the theoretical RI, they were all higher than the RI of silica at 580nm (1.4587), confirming that the addition of Zr effectively increased the refractive index as intended. The lower RI compared to the theoretical value can be attributed to the films being coated and fixed on a substrate. When a free-standing object undergoes thermal treatment, shrinkage occurs in all directions due to the elimination of the organic component, even if the temperature is below the glass transition temperature (Tg) or sintering temperature (Ts). However, when the material is in the form of a thin film fixed on a substrate, the horizontal shrinkage is restricted unless cracks form, and only vertical shrinkage can occur. This also explains why the thickness of the thin film changed more compared to the shrinkage of printed free-standing objects before (1500-1700 nm) and after (400 to 600 nm) thermal treatment. Moreover, the treatment temperature in the experiments was lower than Tsof most samples with different Zr concentrations, except for the sample with 10 mol% Zr. Therefore, even though vertical shrinkage still occurred to a certain extent, the overall density of the film was lower compared to the free-standing sample, resulting in a lower RI. This phenomenon of low RIis common in sol-gel prepared thin films on substrates. Additionally, it should be noted that the refractive index of free-standing glass optics should be higher than that of thin films.

[0074] As the Zr concentration increased, the k value of each sample also showed an increment, particularly in the UV region (<400 nm). At 5% Zr concentration, there was almost negligible absorption for wavelengths above 300 nm. With a gradual increase in Zr concentrations to 7.2% and 10%, a slight increase in absorption of visible light was observed, but the values remained low, mostly below 0.005. However, the absorption of UV light exhibited a significant increase, reaching a value as high as 0.024 (for 10% Zr at 210 nm). This pronounced increase in absorption in the UV region is primarily attributed to the absorption of the Zr-0 structure, as silica thin films generally exhibit minimal absorption from approximately 300 nm up to the visible light range.

[0075] FIG. 3G shows examples of the refractive index of samples with different zirconium concentration at 580 nm and the corresponding theoretical RI of each sample.

[0076] Example Techniques to 3D Print Imaging Optics

[0077] In one example technique, a 780 nm two-photon laser printing system was utilized for 3D printing optics essential for the assembly of imaging systems. To showcase the superior precision of the system, both a flat element and an aspherical lens structure were fabricated. Following a thermal treatment at 650°C, the surface quality of these objects was assessed. FIG. 9A shows example surface measurements of a TPP printed flat element. FIG. 9B shows example surface measurements of a TPP printed aspherical structure. With a surface roughness of less than 4 nm (FIG. 9A) and a peak-to-valley deviation of ± 135 nm (FIG. 9B), the results indicate that the process achieves a highly controlled surface quality which is crucial for imaging applications.

[0078] To demonstrate the imaging performance of the 3D-printed optics, two types of imaging optics were 3D-printed. The first is a micro-objective encompassing three lens elements. FIG. 10A shows an SEM image of an example glass micro-objective containing 7.2% Zr. The imaging resolution of this objective was demonstrated using a setup outlined elsewhere. FIG. 10B shows an example image of a 1951 USAF target (Group 9). Significantly, the clarity with which the initial three rows of elements from group 9 of the 1951 USAF target are resolved (as shown in FIG. 10B) highlights the achievement of sub-micrometer imaging resolution. Such resolution enables the detailed observation of intricate structures, for example, structures in human mammary gland samples. FIG. 10C shows an example image of a human resting mammary gland captured by anoptical system fabricated using the micro-objective shown in FIG. 10A. An example examination of the imaging performance of the printed objective across different groups of the 1951 USAF target is shown FIG. 11.

[0079] A multi-lens design is crucial for medical applications. To underscore this, a doublet glass microscope was 3D-printed, showcasing its potential as a minimally invasive imaging system. This breakthrough is geared towards laying the groundwork for micro-detection systems specifically designed for organs with smaller lumens. Beyond mere imaging, the system's flexibility encompasses additional modalities, such as accurate tissue sampling, laser-aided therapy, and targeted drug delivery. Importantly, the choice of silica optics over traditional polymers or plastics was influenced by its notable benefits in biocompatibility and enhanced transmission of ultraviol et / blue light. The experimental setup featured the 3D-printed glass objective, placed in proximity to a 10,000-element fiber bundle (PN: FIGH-10-350S, Fujikura), which was aligned with the glass microscope as shown in FIG. 6A. The distal end of this fiber bundle was meticulously situated at the working distance (WD) of a microscope system, equipped with a 10X objective. As illustrated in FIG. 6D, the printed micro-objective was able to resolve the fourth element in Group 7 of a 1951 USAF target. It should be noted that, in FIG. 6D, the honey cone pattern caused by fiber bundle has been removed by imaging processing using software. FIGS. 6B-C show example images, captured using the system shown in FIG. 6A, from a histological section of a fallopian tube and an injected rabbit lung, respectively, underscoring the potential medical applications of the disclosed printing technique.

[0080] In addition to the glass objective tailored for endoscope with fiber bundle, TPP -printed micro-glass optics open the door to creating ultra-compact imaging systems, such as the chip-on- tip design. This design diverges from traditional endoscope designs which rely on a fiber bundle or waveguide to relay light signals from the lens to the camera. Instead, the chip-on-tip design incorporates a sub -millimeter image sensor located directly at the tip of the endoscope, equipped with the lens element. This configuration renders the entire system more streamlined than its conventional counterparts. FIG. 6E shows an example SEM image of a manufactured 6X6 glass micro lens array, and the scheme of the lens array on the CMOS sensor with a pixel size of 1.75 pm X 1.75 pm. FIG. 6F shows an example image, captured by the setup in FIG. 6E, of a resolution target. FIG. 6G shows an example scheme of a setup fabricated using a singular lens. As illustrated in FIGS. 6E and 6G, the glass optics — whether in a lens array or as a single lens — can be affixeddirectly to the COMedia CMOS sensor, which delivers a resolution of 384x384 pixels. This chip features a pixel pitch of 1.75 pm. To maximize the sensor coverage by the mounted lens, each lens was crafted with a square-shaped entrance pupil, ensuring thorough sensor utilization. FIG. 6F showcases an image of the 1951 USAF target (group 1, element 6) captured using a 6x6 glass lens array. Notably, the diameter of this lens array extends beyond the bounds of the available sensor area. FIGS. 6H and 61 show example images produced by the single glass lens, highlighting their unique attributes.

[0081] Example Techniques to 3D Print Multi-Refractive Index Micro-Optics Through SelfWelding of PSQs

[0082] One challenge faced by glass micro-optics lies in the intricate process of assembling two or more optical elements together. This challenge becomes particularly pronounced when dealing with glass objects below 500 micrometers in dimension. Conventional adhesive methods, although effective in many scenarios, present a potential risk of compromising the integrity of optical components of such small scale. While there have been reports of laser welding glass without the use of additives, the precise alignment and welding of micro-sized glass optics at desired positions remains a nontrivial endeavor.

[0083] One notable advantage of the disclosed printable Porous Silica Glasses (PSQs) lies in their inherent self-welding capability. This characteristic provides a high degree of flexibility for constructing objects with multiple components, each possessing varying refractive indices. This self-welding phenomenon occurs due to the formation of Si-O-Si bonds when two closely printed PSQ surfaces come into contact during thermal treatment, as illustrated in FIG. 12A which shows an example scheme of the self-welding process. Zr moieties were not present in the molecular structure. The PSQ-5%Zr shows a much more yellow color compared to the PSQ without Zr, which is due to the interact between BEBP and carboxylic acid. During pyrolysis, Si-O-Si bonds were formed to weld two individual parts. FIG. 12B shows an example image of a USAF target captured with the micro-optics shown in FIG. 12A.

[0084] To confirm this self-welding behavior, three individual rings were initially printed using PSQ-5%Zr. These rings were then manually stacked together before undergoing thermal treatment. As the discrete printed PSQ objects were positioned closely during thermal treatment, an automatic welding process took place, eliminating the need for sintering, melting procedures, or additional welding agents. FIG. 13 A shows an example image of the three stacked, separately-printed PSQ-5%Zr rings after thermal treatment. As shown in FIG. 13 A, the final glass rings remain well- aligned even after experiencing various movements and vibrations, affirming the effectiveness of self-welding. FIG. 13B shows an SEM image of the contacted region between two rings. The closely contacted region in the SEM image (FIG. 13B) confirms that the rings have indeed been welded.

[0085] Furthermore, the experimentation was extended by printing four PSQ-MPTES rings and three PSQ-5%Zr rings and alternatingly stacking them together. FIG. 13C shows an example image of the alternately-stacked individual rings containing 0% Zr and 5% Zr. FIG. 13D shows an example image of the stacked rings after thermal treatment. Following thermal treatment, all color distinctions disappeared, and the rings remained tightly stacked due to the self-welding behavior, demonstrating that PSQs with different Zr concentrations can also achieve self-welding.

[0086] In another example demonstration, two individual lens structures were printed, one containing 0% Zr and the other 5% Zr, respectively, and stacked together (FIG. 12A). Once again, the self-welding process was completed after thermal treatment. To assess the strength of the welding, the components were tested using microfibers to manipulate and stretch the welded components, confirming their secure fusion. FIG. 12B shows an example image captured using the multi-lens objective of FIG. 12A, demonstrating the excellent imaging resolution achieved by this multi-lens objective, which incorporates lenses with varying refractive indices.

[0087] It's noteworthy that despite PSQ-5%Zr displaying approximately 5% greater shrinkage compared to PSQ-MPTES, significant differences in the outer frame were not observed. This observation suggests that the welding behavior somehow mitigated the shrinkage of the PSQ-5%Zr sample, particularly since PSQ-5%Zr exhibits similar shrinkage to PSQ-MPTES at temperatures below 400°C.

[0088] However, when combining PSQs with higher Zr concentrations alongside PSQ-MPTES or PSQ-MMTS, there is potential for a more pronounced mismatch, which could pose alignment challenges. This issue can be addressed by introducing redundancy to components with higher shrinkage and incorporating designed position-limiting structures within the contact region. These strategic measures will help compensate for the higher shrinkage, ensuring precise alignment.

[0089] One example embodiment disclosed in the present patent document relates to a strategy to print inorganic glass utilizing PSQ. The use of random ring structure in silsesquioxane enables TPP 3D printing without the need for additional solvents or reactive monomers, resulting inreduced shrinkage after thermal treatment compared to POSS-based materials. Moreover, the absence of reactive methoxy or silanol groups enhances the stability of PSQ against moisture, making it more suitable for certain applications. The similar molecular structures of PSQs with different Zr concentrations and refractive index allows self-welding of individually printed components, which further enhances the ability of this PSQ system for a wider range of applications.

[0090] Experimental results demonstrate that the silsesquioxane produced by MPTES exhibits a final shrinkage of 32.8%, which is further lowered to only 28.5% with the MMTS variant. Additionally, high printing resolutions of approximately 75 nm feature size and a spatial resolution of at least 430 nm (distance between two printed line structure) can be achieved by TPP. The ability to tune the RI of the final glass through the introduction of zirconium-MAA complex opens up possibilities for a variety of optical applications. It has been observed that introducing 10 mol% Zr brings RI up to 1.52134. The fabricated micro-optics with low surface roughness (<4 nm) exhibit excellent imaging performance, achieving high imaging resolution (sub-micrometer) and proving their suitability for real micro-sized bio-samples.

[0091] The disclosed embodiments represent an advancement in the preparation of solvent-free resins for 3D printing inorganic glass structures, offering valuable contributions to the fabrication of micro- or nano-sized glass objects and applications of PSQ in the field of advanced glass manufacturing.

[0092] Example Syntheses of Polymeric Silsesquioxane (PSQ) using MPTES and MMTS

[0093] Methacryloxymethyltrimethoxysilane (MMTS) and 3-methacryloxypropyltriethoxysilane (MPTES) were purchased from Gelest. 4,4'-Bis(diethylamino)benzophenone (BEBP), monomethyl ether hydroquinone (MEHQ), zirconium(IV) propoxide (70 wt. % in 1 -propanol), and Propylene glycol monomethyl ether acetate (PGMEA) were purchased from Sigma-Aldrich.

[0094] In an example synthesis of PSQ using MPTES, MPTES (5 g, 0.017 mol) was mixed with tetrahydrofuran (6 g) in a 50 mL round bottom flask. Deionized water (0.92 g, 0.051 mol) was added to this solution. Under magnetic stirring, 0.17 mL Tetrabutylammonium fluoride solution (1 M in THF) was added dropwise. This solution was allowed to be mixed at room temperature for 2 hours. After that, the solution was poured into 30 mL water and extracted using 8 mL of dichloromethane twice. The combined extracted solution was dried with brine and magnesiumsulfide. After that, 15 mg of 4,4'-Bis(diethylamino)benzophenone (BEBP) was added, and the solution was concentrated to around 5 mL. After it was filtered using a 0.02 gm Anotop filter and the remaining dichloromethane was removed under vacuum leaving a viscous yellow oil. 1H NMR (500 MHz, CDC13) 8 = 6.10-5.96 (m, 1H), 5.53-5.45(m, 1H), 4.20-4.01(m, 2H), 1.92-1.81(m, 3H), 1.80-1.65(m, 2H), 0.75-0.60(m, 2H); 13C NMR (500 MHz, CDC13) 8 = 167.3, 135.9, 124.8, 65.8, 22.1, 17.5, 7.4.

[0095] In an example synthesis of PSQ using MMTS, the procedure is the same as that to synthesize PSQ using MPTES except that the MPTES was replaced with the same mole of MMTS. 5 mg of MEHQ was added as inhibitor to the final resin. The synthesized PSQ-MMTS was placed in fridge for storage.

[0096] Example Synthesis of PSQ with Different Refractive Index

[0097] To tune the refractive index of final glass, zirconium propoxide was selected as the source of zirconium to increase the refractive index. In some implementations, the source of zirconium may be zirconium butoxide, zirconium tert-butoxide, or zirconium isopropoxide. To prepare the PSQ with different zirconium concentrations, the PSQ was firstly synthesized using MPTES (5 g, 0.017 mol) as described above. The zirconium was stabilized using 3 equivalents of methacrylic acid compared to the mole of zirconium propoxide. For example, to synthesize PSQ with 5 mol% zirconium, the zirconium propoxide (70 wt% in propanol, 0.424 g, 0.0009 mol) was mixed with methacrylic acid (0.235 g, 0.0027 mol) in a sealed glass vial. This slightly yellow solution was stirred at room temperature for 24 hours. After that, it was mixed with the prepared PSQ to form a homogenous solution. For samples containing 5 mol% and 7.2 mol% zirconium, all the volatiles were removed under vacuum to give a yellow-orange viscous oil. For sample containing 10 mol% zirconium, 0.15 g of dodecanol was added as a viscosity controller before removing all volatiles. The resulting resin is yellow-orange viscous oil.

[0098] The refractive index of different PSQs were measured using an ellipsometer. To measure the refractive index, thin films were prepared as explained in the example procedure presently disclosed. The as-synthesized oil material was diluted using THF with the volume ratio of 1 :2. Quartz thin slides were used as the substrate since quartz has good stability within the temperature range during thermal treatment. The diluted solution was first dropped and spread on the whole surface of the quartz slide with proper dimension. The spin coating was done with 4000 rpm for 1 min. The obtained coated slides were then exposed under UV for 10 min to cure the thin film. Thethin films prepared using this procedure have thicknesses between 1500 to 1700 nm. After the curing, the quartz with thin film was heated to 650 °C with a rate of 1 °C / min and kept at 650 °C for 2 hours to get inorganic glass thin films. No crack was observed for all the glass films prepared using this procedure. After the thermal treatment, the films have thicknesses between 400 to 600 nm.

[0099] Example Two-Photon Printing of PSQ

[0100] An example printing system that can be implemented with the disclosed PSQ resins includes a 780 nm femtosecond fiber laser with 150 fs pulse, 77 MHz, and a maximum power of 130 mW. The full-width half maximum (FHWM) of the beam was 5 mm, 83% filling the objective (NA=0.6). The component was printed with a 1.17 nJ pulse energy and 16900 pm / s on the quartz substrate. After printing, the uncured resin was washed using PGMEA and ethanol and dried before thermal treatment.

[0101] Example Techniques to Thermally Convert Printed Parts to Inorganic Glass

[0102] In one example technique to thermally convert printed parts to inorganic glass, the printed parts were heated in a furnace to 650 °C with a heating rate of 1 °C / min in air. The sample was then kept at 650 °C for 2 hours and gradually cooled down to room temperature.

[0103] Example Techniques to Print Optics with Multi-Components Through SelfWelding

[0104] In one example technique, individual single lens optics were printed using different PSQ resin (PSQ-MPTES, PSQ-5%Zr). After printing and washing, the PSQ-5%Zr sample was carefully transferred on top of the PSQ-MPTES sample using a micro fiber. The stacked microoptics were placed into a furnace to go through the pyrolysis process described above. The welding process finished automatically during the pyrolysis process.

[0105] Example Preparation of Zr-MAA Complex

[0106] Zirconium propoxide (70 wt% in 1 -propanol) was mixed with 3 equivalents of MAA to form the Zr-MAA complex.1H NMR and13C NMR were used to characterize the product. No recrystallization or other purification was attempted. From previous literature, it is likely that the final form of the complex would be Zrx(OCH2CH2CH3)v(OOC4H5)z, where x doesn’t equal to 1. FIG. 14 shows example 'H and13C NMR of the mixture formed by 1 equivalent of zirconium propoxide and 3 eq of MAA (24h mixing). FIG. 15 shows an example NMR spectra comparisonbetween the zirconium propoxide-MAA mixture and pristine MAA. The broad peaks in both!H NMR (6.18 ppm, 5.49 ppm, 1.85 ppm) and13C NMR (137.7 ppm, 126.4 ppm, 17.6 ppm) indicate that almost all the MAA have bonded to the Zr. No peak belonging to pristine MAA molecules was observed (FIGS. 14 and 15). One byproduct, propyl methacrylate, was found in the final product mixture. This ester was formed from the esterification between MAA and propanol. This can be confirmed from exemplary HSQC spectra of zirconium propoxide-MAA mixture shown in FIG. 16, the example HMBC spectrum of zirconium propoxide-MAA mixture shown in FIG. 17, and the example COSY 2D spectrum of zirconium propoxide-MAA mixture shown in FIG. 18. This phenomenon was also reported in a previous study and it is difficult to avoid. Applying vacuum to the Zr-MAA complex mixture removed most of the propanol to result a solid product which can be re-dissolved in organic solvents. FIG. 19 shows an example comparison of!H NMR spectra of zirconium propoxide-MAA mixture before and after vacuum drying. FIG. 19B shows that after vacuuming, the sharp peaks (1.59 ppm, 0.91 ppm) and the broad OH peak (2.56 ppm) belonging to propanol disappeared. Meanwhile, most of the propyl methacrylate remained (FIG. 19A) due to the relatively high boiling point. However, based on the integration from the!H NMR, the total ratio of propyl methacrylate is less than 10 mol% compared to the number of bonded MAA molecules.

[0107] FIG. 20 shows a schematic of an example technique, in accordance with implementations of the disclosed technology, to assemble a portion of a multi-component optical element. FIG. 20 (left) shows a first part of the multi-component optical element and a second part of the multi-component element separated by a gap. At the joint area, indicated in FIG. 20 using arrows to show the direction of contact, a surface of the first part and a surface of the second part are brought into contact. FIG. 20 (right) shows the first part and the second part with their surfaces in contact. While these surfaces are in contact with one another at the joint area, the first part and the second part can be heated to enable the first and second parts to self-weld across the joint area.

[0108] FIG. 21 shows a flow diagram of an example method 2100 for three-dimensional (3D) printing of a multi-component optical glass element. At operation 2101, the method 2100 comprises printing, via two-photon polymerization, a first part of the multi-component optical glass element using a polymeric silsesqui oxane (PSQ) resin. At operation 2102, the method 2100 comprises printing, via two-photon polymerization, a second part of the multi-component opticalglass element using the PSQ resin. At operation 2103, the method 2100 comprises causing a first surface of the first part to be in contact with a second surface of the second part. At operation 2104, the method 2100 comprises causing the first part and the second part to self-weld by heating the first part and the second part, while the first surface and the second surface are in contact with one another, such that Si-O-Si bonds are formed between the first surface and the second surface.

[0109] FIG. 22 shows a flow diagram of an example method 2200 of preparing a resin for three-dimensional (3D) printing of a glass component based on two-photon polymerization (TPP). At operation 2201, the method 2200 comprises forming a first mixture comprising a monomer, a first liquid, and a second liquid. At operation 2202, the method 2200 comprises using an F- catalyzation mechanism to form a product comprising silesquioxane, based on the first mixture, that is fully hydrolyzed and condensed. At operation 2203, the method 2200 comprises filtering the product to obtain the resin in purified form.

[0110] FIG. 23 shows a flow diagram of an example method 2300 for three-dimensional (3D) printing of a multi-component optical glass element using two-photon polymerization (TPP). At operation 2301, the method 2300 comprises printing a first part of the multi-component optical glass element using a first polymeric silsesquioxane (PSQ) resin. At operation 2302, the method 2300 comprises printing a second part of the multi-component optical glass element using a second PSQ resin. At operation 2303, the method 2300 comprises forming at least a portion of the multicomponent optical glass element using the first part and the second part.

[0111] Embodiments of the disclosed technology support inter alia the following technical solutions that solve the technical problem of producing images obtained via NIR fluorescence and projecting patterns associated with the images onto a sample.

[0112] 1. A method for providing a solvent-free polymeric silsesquioxane (PSQ) resin for three-dimensional printing.

[0113] 2. The method of technical solution 1, wherein nanostructures with feature sizes below 80 nm are achieved.

[0114] 3. The method of technical solution 1, comprising incorporating zirconium moi eties to enable fabrication of glass micro-optics with varying refractive indices.

[0115] 4. A solvent-free polymeric polymeric silsesquioxane (PSQ) resin disclosed herein.

[0116] 5. Any method for producing a solvent-free silsesquioxane disclosed herein.

[0117] 6. A method for three-dimensional (3D) printing of a multi-component optical glasselement, comprising: printing, via two-photon polymerization, a first part of the multi-component optical glass element using a polymeric silsesquioxane (PSQ) resin; printing, via two-photon polymerization, a second part of the multi-component optical glass element using the PSQ resin; causing a first surface of the first part to be in contact with a second surface of the second part; and causing the first part and the second part to self-weld by heating the first part and the second part, while the first surface and the second surface are in contact with one another, such that Si-O- Si bonds are formed between the first surface and the second surface.

[0118] 7. The method of technical solution 6, wherein the first part and the second part comprise different materials having different refractive indices.

[0119] 8. The method of technical solution 6, wherein refractive indices of the first part and the second part are tunable, respectively, based on a concentration of zirconium in the PSQ resin.

[0120] 9. The method of claim technical solution 8, wherein the PSQ resin used in the printing of the first part comprises a first concentration of zirconium, and the PSQ resin used in the printing of the second part comprises a second concentration of zirconium that is different from the first concentration.

[0121] 10. The method of technical solution 6, further comprising: printing, via two- photon polymerization, additional parts of the multi-component optical glass element using the PSQ resin, wherein the heating is performed while at least one surface of the additional parts is in contact with a surface of the first part or the second part, and wherein the heating results in selfwelding of the additional parts to the surface of the first part or the second part.

[0122] 11. The method of technical solution 6, wherein the heating is performed at a temperature that is less than or equal to 650°C.

[0123] 12. The method of technical solution 6, wherein the multi-component optical glass element comprises feature sizes less than 80 nm.

[0124]

[0125] 13. The method of technical solution 6, wherein at least a portion of the multicomponent optical glass element is formed by the causing the first part and the second part to selfweld.

[0126] 14. The method of technical solution 6, wherein the multi-component optical glass element is operable to image a nanoscale structure.

[0127] 15. A method of preparing a resin for three-dimensional (3D) printing of a glass component based on two-photon polymerization (TPP), comprising: forming a first mixture comprising a monomer, a first liquid, and a second liquid; using an F- catalyzation mechanism to form a product, based on the first mixture and comprising silsesquioxane, that is fully hydrolyzed and condensed; and filtering the product to obtain the resin in purified form.

[0128] 16. The method of technical solution 15, wherein the resin is a viscous oil.

[0129] 17. The method of technical solution 15, wherein the monomer is 3- methacryloxypropyltriethoxysilane (MPTES).

[0130] 18. The method of technical solution 15, wherein the monomer is 3- methacryloxypropyltrimethoxysilane.

[0131] 19. The method of technical solution 15, wherein the monomer isMethacryl oxy methy l)trimethoxy sil ane .

[0132] 20. The method of technical solution 15, wherein the monomer isMethacryl oxy methy 1 )tri ethoxy sil ane .

[0133] 21. The method of technical solution 15, wherein the monomer comprises trialkoxy silane molecules that include one acrylate or methacrylate functional group.

[0134] 22. The method of technical solution 15, wherein the first liquid is tetrahydrofuran and the second liquid is water.

[0135] 23. The method of technical solution 15, wherein forming the resin comprises: adding tetrabutylammonium fluoride solution to the first mixture to obtain a solution, obtaining an extraction from the solution using dichloromethane, and adding 4'- Bis(diethylamino)benzophenone (BEBP) to the extraction.

[0136] 24. The method of technical solution 15, wherein the resin is stabilized against moisture by absence of reactive methoxy and silanol groups from the resin.

[0137] 25. The method of technical solution 15, wherein the resin is solvent-free.

[0138] 26. The method of technical solution 15, wherein the resin is implemented for 3D printing of an optical glass component.

[0139] 27. The method of technical solution 15, wherein monomethyl ether hydroquinone(MEHQ) is added to the resin as an inhibitor.

[0140] 28. The method of technical solution 26, wherein the optical glass component comprises feature sizes less than 80 nm.

[0141] 29. The method of technical solution 28, further comprising introducing a number of moieties into the resin, wherein a refractive index of the glass component is linearly tunable based on the number of moieties.

[0142] 30. The method of technical solution 29, wherein the moieties comprise zirconium.

[0143] 31. The method of technical solution 15, further comprising: stabilizing a concentration of molecules from a source using a third liquid; mixing the stabilized concentration of molecules into the resin to form a homogenous solution comprising the stabilized concentration of molecules; and removing volatiles from the homogenous solution.

[0144] 32. The method of technical solution 31, wherein the source is zirconium propoxide, zirconium butoxide, zirconium tert-butoxide, or zirconium isopropoxide, wherein the third liquid is methacrylic acid.

[0145] 33. The method of technical solution 31, wherein the resin is implemented for 3D printing of an optical component, wherein a refractive index of the optical component is based on the concentration of molecules, wherein the refractive index is between 1.4 and 1.7.

[0146] 34. The method of technical solution 31, wherein the homogenous solution is implemented for 3D printing of an optical component comprising glass.

[0147] 35. A method for three-dimensional (3D) printing of a multi-component optical glass element using two-photon polymerization, comprising: printing a first part of the multicomponent optical glass element using a first polymeric silsesqui oxane (PSQ) resin; printing a second part of the multi-component optical glass element using a second PSQ resin; and forming at least a portion of the multi-component optical glass element using the first part and the second part.

[0148] 36. The method of technical solution 35, wherein the first PSQ resin and the secondPSQ resin comprise different amounts of zirconium alkoxide.

[0149] 37. A two-photon polymerization (TPP) three-dimensional (3D) printing system, comprising: a stage; a lens; and a light source configured to direct light, via the lens, towards a polymeric silsesqui oxane (PSQ) resin disposed upon the stage to cause polymerization of the PSQ resin at one or more predetermined locations, wherein the TPP 3D printing system is operable to: print a first part of a multi-component optical glass element using a first PSQ resin; print a second part of the multi-component optical glass element using a second PSQ resin to form at least a portion of the multi-component optical glass element using the first part and the second part.

[0150] 38. The three-dimensional printing system of technical solution 37, wherein the light source is a femtosecond laser.

[0151] 39. The three-dimensional printing system of technical solution 37, wherein a refractive index of the first part and the second part differ from each other based on a concentration of zirconium in the first PSQ resin and the second PSQ resin, respectively.

[0152] 40. A resin for a three-dimensional printing system based on two-photon polymerization (TPP), comprising: multiple silesquioxanes structures that each comprise silicon, oxygen, and an organic functional group, wherein the multiple silesquioxanes structures are configured in a random ring structure, and wherein at least some of the multiple silesquioxanes structures are of different molecular weights.

[0153] 41. The resin of technical solution 40, wherein the random ring structure is flexible.

[0154] 42. The resin of technical solution 40, wherein the resin is synthesized using a synthesis process that uses 3-methacryloxypropyltriethoxysilane (MPTES), 3- methacryloxypropyltrimethoxysilane, Methacryloxymethyl)trimethoxysilane, or Methacryloxymethyl)tri ethoxysilane as a primary monomer.

[0155] 43. The resin of technical solution 40, wherein the resin is synthesized using a synthesis process that uses a primary monomer comprising trialkoxy silane molecules that include one acrylate or methacrylate functional group.

[0156] 44. The resin of technical solution 42, wherein an F- catalyzation mechanism used in the synthesis process results in the resin being fully hydrolyzed and condensed.

[0157] 45. The resin of technical solution 40, wherein the resin is a viscous oil.

[0158] 46. The resin of technical solution 40, wherein the resin is solvent-free.

[0159] Various components may be controlled or various operations may be performed via implementations using a processor / controller that is configured to include, or be coupled to, a memory that stores processor executable code that causes the processor / controller carry out various computations and processing of information. The processor / controller can further generate and transmit / receive suitable information to / from the various system components, as well as suitable input / output (IO) capabilities (e.g., wired or wireless) to transmit and receive commands and / or data. The processor / controller may, for example, provide signals to control the operation of various components such as light sources and detectors that are disclosed herein.

[0160] Various information and data processing operations described herein may be implemented in one embodiment by a computer program product, embodied in a computer- readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), cloud storage, etc. Therefore, the computer-readable media that is described in the present application comprises non- transitory storage media. Generally, program modules may include routines, programs, objects, omponents, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

[0161] Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

Claims

CLAIMS1. A method for three-dimensional (3D) printing of a multi-component optical glass element, comprising: printing, via two-photon polymerization, a first part of the multi-component optical glass element using a polymeric silsesquioxane (PSQ) resin; printing, via two-photon polymerization, a second part of the multi-component optical glass element using the PSQ resin; causing a first surface of the first part to be in contact with a second surface of the second part; and causing the first part and the second part to self-weld by heating the first part and the second part, while the first surface and the second surface are in contact with one another, such that Si-O-Si bonds are formed between the first surface and the second surface.

2. The method of claim 1, wherein the first part and the second part comprise different materials having different refractive indices.

3. The method of claim 1, wherein refractive indices of the first part and the second part are tunable, respectively, based on a concentration of zirconium in the PSQ resin.

4. The method of claim 3, wherein the PSQ resin used in the printing of the first part comprises a first concentration of zirconium, and the PSQ resin used in the printing of the second part comprises a second concentration of zirconium that is different from the first concentration.

5. The method of claim 1, further comprising: printing, via two-photon polymerization, additional parts of the multi-component optical glass element using the PSQ resin,wherein the heating is performed while at least one surface of the additional parts is in contact with a surface of the first part or the second part, and wherein the heating results in self-welding of the additional parts to the surface of the first part or the second part.

6. The method of claim 1, wherein the heating is performed at a temperature that is less than or equal to 650°C.

7. The method of claim 1, wherein the multi-component optical glass element comprises feature sizes less than 80 nm.

8. The method of claim 1, wherein at least a portion of the multi-component optical glass element is formed by the causing the first part and the second part to self-weld.

9. The method of claim 1, wherein the multi-component optical glass element is operable to image a nanoscale structure.

10. A method of preparing a resin for three-dimensional (3D) printing of a glass component based on two-photon polymerization (TPP), comprising: forming a first mixture comprising a monomer, a first liquid, and a second liquid; using an F- catalyzation mechanism to form a product, based on the first mixture and comprising silsesquioxane, that is fully hydrolyzed and condensed; and filtering the product to obtain the resin in purified form.

11. The method of claim 10, wherein the resin is a viscous oil.

12. The method of claim 10, wherein the monomer is 3-methacryloxypropyltriethoxysilane (MPTES).

13. The method of claim 10, wherein the monomer is 3 -methacryloxypropyltrimethoxy silane.

14. The method of claim 10, wherein the monomer is (Methacryloxymethyl)trimethoxysilane.

15. The method of claim 10, wherein the monomer is (Methacryloxymethyl)tri ethoxy silane.

16. The method of claim 10, wherein the monomer comprises trialkoxy silane molecules that include one acrylate or methacrylate functional group.

17. The method of claim 10, wherein the first liquid is tetrahydrofuran and the second liquid is water.

18. The method of claim 10, wherein forming the resin comprises: adding tetrabutylammonium fluoride solution to the first mixture to obtain a solution, obtaining an extraction from the solution using dichloromethane, and adding 4'-Bis(diethylamino)benzophenone (BEBP) to the extraction.

19. The method of claim 10, wherein the resin is stabilized against moisture by absence of reactive methoxy and silanol groups from the resin.

20. The method of claim 10, wherein the resin is solvent-free.

21. The method of claim 10, wherein the resin is implemented for 3D printing of an optical glass component.

22. The method of claim 10, wherein monomethyl ether hydroquinone (MEHQ) is added to the resin as an inhibitor.

23. The method of claim 21, wherein the optical glass component comprises feature sizes less than 80 nm.

24. The method of claim 23, further comprising introducing a number of moieties into the resin, wherein a refractive index of the glass component is linearly tunable based on the number of moieties.

25. The method of claim 24, wherein the moieties comprise zirconium.

26. The method of claim 10, further comprising: stabilizing a concentration of molecules from a source using a third liquid; mixing the stabilized concentration of molecules into the resin to form a homogenous solution comprising the stabilized concentration of molecules; and removing volatiles from the homogenous solution.

27. The method of claim 26, wherein the source is zirconium propoxide, zirconium butoxide, zirconium tert-butoxide, or zirconium isopropoxide, wherein the third liquid is methacrylic acid.

28. The method of claim 26, wherein the resin is implemented for 3D printing of an optical component, wherein a refractive index of the optical component is based on the concentration of molecules, wherein the refractive index is between 1.4 and 1.7.

29. The method of claim 26, wherein the homogenous solution is implemented for 3D printing of an optical component comprising glass.

30. A method for three-dimensional (3D) printing of a multi-component optical glass element using two-photon polymerization, comprising: printing a first part of the multi-component optical glass element using a first polymeric silsesqui oxane (PSQ) resin; printing a second part of the multi-component optical glass element using a second PSQ resin; and forming at least a portion of the multi-component optical glass element using the first part and the second part.

31. The method of claim 30, wherein the first PSQ resin and the second PSQ resin comprise different amounts of zirconium alkoxide.

32. A two-photon polymerization (TPP) three-dimensional (3D) printing system, comprising: a stage; a lens; and a light source configured to direct light, via the lens, towards a polymeric silsesquioxane (PSQ) resin disposed upon the stage to cause polymerization of the PSQ resin at one or more predetermined locations, wherein the TPP 3D printing system is operable to: print a first part of a multi-component optical glass element using a first PSQ resin; print a second part of the multi-component optical glass element using a second PSQ resin to form at least a portion of the multi-component optical glass element using the first part and the second part.

33. The three-dimensional printing system of claim 32, wherein the light source is a femtosecond laser.

34. The three-dimensional printing system of claim 32, wherein a refractive index of the first part and the second part differ from each other based on a concentration of zirconium in the first PSQ resin and the second PSQ resin, respectively.

35. A resin for a three-dimensional printing system based on two-photon polymerization (TPP), comprising: multiple silesquioxanes structures that each comprise silicon, oxygen, and an organic functional group, wherein the multiple silesquioxanes structures are configured in a random ring structure, and wherein at least some of the multiple silesquioxanes structures are of different molecular weights.

36. The resin of claim 35, wherein the random ring structure is flexible.

37. The resin of claim 35, wherein the resin is synthesized using a synthesis process that uses 3 -methacryloxypropyltri ethoxysilane (MPTES), 3 -methacryloxypropyltrimethoxy silane, (Methacryloxymethyl)trimethoxysilane, or (Methacryloxymethyl)triethoxysilane as a primary monomer.

38. The resin of claim 35, wherein the resin is synthesized using a synthesis process that uses a primary monomer comprising trialkoxy silane molecules that include one acrylate or methacrylate functional group.

39. The resin of claim 37, wherein an F- catalyzation mechanism used in the synthesis process results in the resin being fully hydrolyzed and condensed.

40. The resin of claim 35, wherein the resin is a viscous oil.

41. The resin of claim 35, wherein the resin is solvent-free.

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