Traditional glassmaking techniques can be costly and slow, and 3D printing glass often results in rough textures, making them unsuitable for smooth lenses. Using a new laser-based Volumetric Additive Manufacturing (VAM) approach — an emerging technology in near-instant 3D printing — researchers at Lawrence Livermore National Laboratory (LLNL) and the University of California, Berkeley, have demonstrated the ability to 3D print microscopic objects in silica glass, part of an effort to produce delicate, layer-less optics that can be built in seconds or minutes.
Nicknamed “the replicator” after the fictional device in “Star Trek” that can instantly fabricate nearly any object, the Computed Axial Lithography (CAL) technology developed by LLNL and UC Berkeley is inspired by computed tomography (CT) imaging methods. CAL works by computing projections from many angles through a digital model of a target object, optimizing these projections computationally and then delivering them into a rotating volume of photosensitive resin using a digital light projector. Over time, the projected light patterns reconstruct, or build up, a 3D light dose distribution in the material, curing the object at points exceeding a light threshold while the vat of resin spins. The fully formed object materializes in mere seconds — far faster than traditional layer-by-layer 3D printing techniques — and then the vat is drained to retrieve the part.
Combining a new microscale VAM technique called micro-CAL, which uses a laser instead of an LED source, with a nanocomposite glass resin developed by the German company Glassomer and the University of Freiburg, UC Berkeley researchers reported the production of sturdy, complex microstructure glass objects with a surface roughness of just six nanometers with features down to a minimum of 50 microns.
UC Berkeley Associate Professor of Mechanical Engineering Hayden Taylor, the project’s Principal Investigator, said the micro-CAL process, which produces a higher dose of light and cures 3D objects faster and at higher resolution, combined with the nanocomposite resins characterized at LLNL proved a “perfect match for each other,” creating “striking results in the strength of the printed objects.”
The team compared the breaking strength of glass built with micro CAL against objects of the same size made by a more conventional layer-based printing process. The team found the breaking loads of CAL-printed structures were more tightly clustered together, meaning that researchers could have more confidence in in the breaking load of CAL-printed components over conventional techniques.
For the past several years, the LLNL/ UC Berkeley VAM collaboration has experimented with different resins and materials to create intricate objects. The latest advancement stems from a study with UC Berkeley to discover new classes of versatile materials that could expand the range of chemistries and material properties achievable through the VAM method.
According to the researchers. VAM-printed glass could impact solid-glass devices with microscopic features, produce optical components with more geometric freedom and at higher speeds and could potentially enable new functions or lower-cost products.
Real-world applications could include micro-optics in high-quality cameras, consumer electronics, biomedical imaging, chemical sensors, virtual-reality headsets, advanced microscopes and microfluidics with challenging 3D geometries such as “lab-on-a-chip” applications (where microscopic channels are needed for medical diagnostics), fundamental scientific studies, nanomaterial manufacturing, and drug screening.