Several methods have recently been proposed for improving the processing speed of the popular two-photon polymerization process. One such method makes use of a spatiotemporal focusing technique to achieve a planar projection printing strategy. This works uses a projection two-photon polymerization process in a continuous fashion to fabricate complex 3D structures at a large print rate while maintaining smooth surface features. Fabrication of millimeter scale structures are achievable with this continuous, layer-by-layer projection two-photon lithography system.

3D printing has revolutionized the manufacturing of volumetric components and structures for use in various fields. Owing to the advent of photocurable resins, several fully volumetric light-based techniques have been recently developed to push further the limitations of 3D printing. However, these new approaches only work with relatively transparent resins so that the light is not impacted along its propagation through the material. Herein, we present a method to address this problem and print in scattering materials. It consists of characterizing how light is distorted by the curable resin and then applying a digital correction to the light patterns to counteract the effect of scattering. Using a tomographic volumetric printer, we experimentally demonstrate the importance of taking light scattering into account when computing the projected patterns and show that our applied correction significantly improves printability.

Refractory alloys have extraordinary resistance to heat and wear with superior durability, are often the desired material for extreme environment applications such as space craft, missiles, and hypersonic vehicles. Due to the difficulty and high cost associated with manufacturing in complex shape, their utilization has been hampered even in the most demanding applications. Additive Manufacturing, 3D printing, on the other hands has demonstrated a superior shape producing capability that is unattainable with traditional manufacturing processes. Develop and mature 3D printing of refractory metal alloys have greatly enhance the extreme environment product’s performance and lowering the cost. This work demonstrated a robust 3D printing process with superior materials properties, significant leap in producing highly sophisticated geometries, and sufficiently lowered manufacturing cost. A case study of performance gain in sophisticated Nb C103 engineered hardware will also be presented.

Techniques for three-dimensional (3d) printing of glass have opened the door to novel glass structures with both unconventional structures and tailored composition. The state-of-the art in glass 3d printing and associated challenges will be presented. Emphasis will be placed on the direct ink writing approach, which can be used to produce multi-composition optics such as GRIN lenses. The discussion will cover formulation science, mass transport in multi-material systems, as well as strategies for formation of glass and multi-material optics.

The additive manufacturing of geometrically complex parts of pure copper using laser assisted powder bed fusion (LPBF) is demonstrated. The high thermal and electrical conductivity of pure copper combined with the geometric freedom of the LPBF process offers a wide range of applications. We demonstrate the fabrication of parts combining a high homogeneous density with complex geometries by adapting the laser power to the available thermal mass. This is done by applying a simple model which calculates the required laser power based on available thermal mass approximated by the local geometry.

The development of composite-based manufactured parts has been led, by the need of the aerospace industry to reduce the weight of aircrafts while maintaining a very good structural performance. The trend to use thermoplastic instead of thermoset resin enables even lighter parts, nevertheless it involves laser heating instead of IR lamp heating. We describe the development of a laser beam-shaper based on Multi-Plane Line Conversion technology delivering a tailored top-hat beam profile on the composite fiber to optimize its consolidation and therefore final properties. We demonstrate the performance of the process and describe the optical performance of the beam shaper.

In this work, we report on the conformal laser printing and sintering of Ag nanoparticle inks applied on particularly sensitive substrates and structures. The latter involve challenging patterns with periodicity and aspect ratio in the nano to 100-micron scale. We investigate the effect of a number of essential to the laser sintering technique parameters, such as the laser wavelength, repetition rate, pulse duration and the pulse to pulse spatial and temporal overlap. The demonstrated results show that laser printing and sintering can offer specific solutions to particularly challenging use cases and applications in flexible electronics.

Based on the underlying printing resolution Two-Photon Polymerization (TPP) can be distinguished into 3D Lithography and Micro 3D Printing applications. Both of these fields will be discussed in terms of the requirements on the fabrication process such as exposure strategy, overall resolution and accessible print height among others. Enabling both 3D Lithography and Micro 3D Printing in one TPP laser system imposes certain challenges which will be addressed with solutions being presented.

Direct laser writing (DLW) emerged as one of the technologies promising to overcome challenges posed by the field of medicine. It combines additive and subtractive manufacturing, sub-diffraction limited resolution, and complete design freedom of manufactured structures. There is a drive to push it from laboratory-level use to a widespread solution. Here we present several examples of how DLW can be used for it. It includes high-speed printing of flexible medical scaffolds. Lab-on-chip and organ-on-chip devices, including namely cell perforator, slow flow meter, and macromolecule separator. We show how to improve fabrication throughput without compromising fabrication resolution and/or quality.

Two-photon polymerization (TPP) is a prevalent 3D nanofabrication tool due to its superior resolution. However, the serial nature of the printing process often limits it applicability. Projection-based TPP in combination with spatiotemporal focusing using a digital micromirror device can be utilized to increase the scalability of the printing process while limiting the loss of resolution. A model is developed to simulate photopolymerization in the spatiotemporal focusing projection-based process. This model is used to better understand the 3D spatial and temporal interactions during the printing process and their effect on printing accuracy.

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.

3D structures made out of glass can be used in various fields starting from optical components or microfluidic devices to micromechanics. Selective laser etching (SLE) is a unique technology that allows the production of low surface roughness (around 200 nm RMS) and a high aspect ratio (around 1000) 3D structures. However, some advanced applications as biomedical microfluidics and optical devices require to increase these aspects. In this work, we present SLE technological improvements towards better surface roughness and higher aspect ratio structures. Chemical etching process improvements enable to increase selectivity up to 3000 which ameliorates the accuracy and possible aspect ratio of the structures.

Aiming to harness the unique capabilities of laser printing, in this study, we present our latest results on the transfer and photo-crosslinking of cell-laden bioinks comprising different hydrogels, using a dual laser beam configuration. Results from different laser sources with ns and sub-ns pulse duration and different repetition rates are also presented to highlight the effect of the laser parameters on the printing and photo-crosslinking of the cell-laden patterns. The printing outcome is correlated with the cell growth of different cell-laden bioinks, while immunochemical staining is also employed to study potential cellular damage.

Identification of grain boundary crossing in aluminum samples by use of machine learning algorithms on pulsed laser ultrasound signals