Ceramic materials have numerous industrial applications thanks to their high chemical, mechanical, and thermal resistances. Precisely because of these reasons, producing parts with these materials is technically challenging with conventional subtractive manufacturing methods. Additive manufacturing is a promising alternative to fabricate ceramic parts with complex geometries. Recent works have demonstrated the fabrication of micrometric tools layer-by-layer, by two-photon polymerization of preceramic materials, with subsequent polymer-to-ceramic conversion through the pyrolysis step. Two-photon polymerization exhibits very high
printing resolutions, typically at the cost of print speed and size. On the other hand, tomographic volumetric 3D printing has been used to rapidly produce larger objects
in the cm-scale with different materials, such as acrylates, cell-compatible hydrogels and thiol-ene photoresins. Tomographic volumetric 3D printing uses one-photon polymerization; which reduces the achievable resolution but strongly increases the printing speed and achievable size. Additionally, tomographic volumetric 3D printing has the advantage of printing hollow structures without the need of support structures.
Here we show that tomographic volumetric additive manufacturing can be applied to the fabrication of ceramic parts from liquid SiOC-based precursors. We use a reverse tomographic technique that consists of collimating light from a
405 nm laser, which is modulated into dynamic patterns by means of a digital micromirror device, to polymerize a viscous liquid ceramic precursor within a rotating vial. After printing, the unpolymerized monomer is washed away with organic solvents, leaving the green body that is pyrolyzed into the final ceramic part. We show the fabrication of smooth parts with high ceramic conversion.
We present a fiber-based 3D printing system with the highest printing resolution. Fabricated lines and microstructures are presented too. A microlens (NA 0.9) is printed in the Nanoscribe 3D-printer and attached to the fiber. A femtosecond laser (780nm, 80MHz) is used for two-photon polymerization and the focused spot on the tip of the lens is generated by wavefront shaping with the Transmission Matrix method. The spot size (lens with NA 0.9) is compared to the spot size of the fiber (NA 0.29) and to the spot size obtained when a commercially available microlens is attached (NA 0.54). Exposure tests are conducted by printing lines or voxels on a photosensitive resin and finally a prepared high aspect ratio structure is used for demonstrating the utility of a fiber-3D printing system to reach confined areas for microfabrication.
We propose a data-driven approach for light transmission control inside multimode fibers (MMFs). Specifically, we show that a convolutional neural network is able to reconstruct amplitude/phase modulated images from scrambled amplitude-only images obtained at the output of a 0.75m long MMF with a fidelity (correlation) as high as ~98%. We show that the trained network shows good generalization as well. In particular, it is shown that the network is able to reconstruct images that do not belong to train/test datasets.
We show that a multimode fiber can be used to deliver shaped light, either continuous wave or ultra fast pulses, in a resin in order to build useful complex three dimensional objects in areas difficult or impossible to reach with conventional manufacturing tools. We show complex objects that are made by additive manufacturing with either a single photon or a 2 photon process. We investigate the build volume and resolution that are possible by engineering the fiber tip.
KEYWORDS: Additive manufacturing, Endoscopy, Manufacturing, Single photon, Multimode fibers, 3D printing, Graded index fibers, Energy transfer, Diffraction, Digital micromirror devices
We show that a multimode fiber which can be either a graded index fiber or fiber bundle can be used to deliver shaped light to build useful complex parts in areas difficult or impossible to reach with conventional manufacturing tools. We will show complex objects of micrometer scale that are made by additive manufacturing with either a single photon or a 2 photon process. The large effective core area of the multimode fiber allows two orders of magnitude higher pulsed energy transfer while maintaining a spatial and temporal diffraction limit. This enable both subtractive and additive manufacturing.
Herein, we demonstrated a T-shaped whispering gallery modes (WGMs) excitation system including a tapered single mode fiber (SMF), a tapered microstructured optical fiber (MOF) and a BaTiO3 microsphere for efficient light coupling and routing between the two fibers. The BaTiO3 microsphere is semi-immersed into the capillary of a tapered MOF, while the tapered SMF is placed perpendicularly to MOF in a contact with equatorial region of the microsphere. Based on that, three channels joined by the microsphere are formed, and excitation and measurement of WGMs is possible either using the SMF or the MOF taper. The measured WGMs spectra reveal light routing along Q-factors between 4500 and 6100, along with scattering signal with all three fiber ports and parities.
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