Free-form microoptics is a promising field showing immense potential in providing functional tools for light control, imaging and material processing. At the moment there is a huge drive in merging these objects to mesoscale – ensuring nano-/micro-features yet being mm-cm in overall size. One of the promising technologies to produce such elements is 3D laser lithography (3DLL). It has been shown to be a superb for fabrication of 3D objects with resolution and surface roughness control down to nm level with overall size to cm range . For this reason it was employed to manufacture integrated 3D optical elements on functional substrates for spatial light control , imaging  and material processing .
Despite current progress there is some limitations concerning mesooptical element 3D printing. Common 3DLL systems uses galvo-scanners for beam deflection. While it can be very rapid (translation velocity in cm/s range), only objects that do not exceed working field of an objective can be printed continuously, which is ~100 µm for objectives having NA>1. Segment-by-segment fabrication have to be employed for bigger objects. At every edge where two segments meet, this induces defects called “stitches”. In optical element, it forces to sacrifice their quality  or use alternative manufacturing techniques .
In this work we present a stitch-free 3D printing of functional mesoscale lenses with an overall size up to several mm. These include mm sized refractive microlenses, cylindrical and Fresnel lenses. It was made possible by real-time synchronization linear stages and galvo-scanners for rapid (several mm/s translation velocity) continuous writing. Mesooptical elements were produced in a single technological step showing the simplicity and potency of 3DLL. Qualitative and quantitative characterization of mesooptical elements was performed, their optical resiliency (LIDT – Laser Induced Damage Threshold) was assesed. The experimental work proves the 3DLL as suitable technique for the fabrication of diverse mesooptical elements and their function to be practically applicable for light flow, imaging and material processing.
 L. Jonušauskas, S. Juodkazis, and M. Malinauskas, "Optical 3D Printing: Bridging the Gaps in the Mesoscale," J. Opt. 20(5), 053001 (2018).
 A. Žukauskas, V. Melissinaki, D. Kaškelytė, M. Farsari, and M. Malinauskas, "Improvement of the Fabrication Accuracy of Fiber Tip Microoptical Components via Mode Field Expansion," J. Laser Micro. Nanoeng. 9(1), 68-72 (2014).
 T. Gissibl, S. Thiele, A. Herkommer, H. Giessen, "Two-Photon Direct Laser Writing of Ultracompact Multi-Lens Objectives," Nat. Photonics 10(8), 554-560 (2016).
 E. E. Morales-Delgado, L. Urio, D. B. Conkey, N. Stasio, D. Psaltis, and C. Moser "Three-dimensional microfabrication through a multimode optical fiber," Opt. Express 25(6), 703-7045 (2017).
 H. Ni, G. Yuan, L. Sun, N. Chang, D. Zhang, R. Chen, L. Jiang, H. Chen, Z. Gu, and X. Zhao, "Large-Scale Sigh-Numerical-Aperture Super-Oscillatory Lens Fabricated by Direct Laser Writing Lithography", RSC Advances 8(36), 20117-20123 (2018).
 X. Chen, W. Liu, B. Dong, J. Lee, H. O. T. Ware. H. F. Zhang, and C. Sun, "High-Speed 3D Printing of Millimeter-Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness," Adv. Mater. 30(18), 1705683 (2018).
Femtosecond laser based 3D nanolithography is gaining popularity in huge variety of fields. However, further improvements are needed to push it from laboratory level use into a wide spread adaptation. In this work we present several advances needed to achieve this goal. First, linear stage and galvo-scanners synchronization is employed to produce stitch-free mm-sized structures with features down to micrometers. Furthermore, it is shown that by varying objective numerical apertures (NA) from 0.8 NA to 1.4 NA voxel size can be tuned in the range of 330 nm to 1.7 μm in transverse and 1.9 μm to 7.9 μm in longitudinal directions, resulting in voxel volumes from 0.017 μm3 to 3.759 μm3 with structuring rates at 2426 μm3/s and 104767 μm3/s respectively at 1 cm/s translation velocity. This two orders of magnitude tunability is exploited to fabricate various functional structures. It includes 2 mm diameter functional micro-lens, cantilever capable of sustaining multiple deformation cycles and free-movable micromechanical spider and squid (overall size - up to 5 mm), showing possibility to print true 3D hinge-like microstructures (feature size down to micrometers) for possible uses in microrobotics. Overall, the presented results show simple and straight-forward way to combine resolution on-demand and stitch-free 3D laser lithography for functional structure fabrication needed for fast expanding science and/or engineering fields.
A novel approach for efficient manufacturing of three-dimensional (3D) microstructured scaffolds designed for cell studies and tissue engineering applications is presented. A thermal extrusion (fused filament fabrication) 3D printer is employed as a simple and low-cost tabletop device enabling rapid materialization of CAD models out of biocompatible and biodegradable polylactic acid (PLA). Here it was used to produce cm- scale microporous (pore size varying from 100 to 400 µm) scaffolds. The fabricated objects were further laser processed in a direct laser writing (DLW) subtractive (ablation) and additive (lithography) manners. The first approach enables precise surface modification by creating micro-craters, holes and grooves thus increasing the surface roughness. An alternative way is to immerse the 3D PLA scaffold in a monomer solution and use the same DLW setup to refine its inner structure by fabricating dots, lines or a fine mesh on top as well as inside the pores of previously produced scaffolds. The DLW technique is empowered by ultrafast lasers - it allows 3D structuring with high spatial resolution in a great variety of photosensitive materials. Structure geometry on macro- to micro- scales could be finely tuned by combining these two fabrication techniques. Such artificial 3D substrates could be used for cell growth or as biocompatible-biodegradable implants. This combination of distinct material processing techniques enables rapid fabrication of diverse functional micro- featured and integrated devices. Hopefully, the proposed approach will find numerous applications in the field of ms, microfluidics, microoptics and many others.
We present a novel approach to manufacturing 3D microstructured composite scaffolds for tissue engineering applications. A thermal extrusion 3D printer – a simple, low-cost tabletop device enabling rapid materialization of CAD models in plastics – was used to produce cm-scale microporous scaffolds out of polylactic acid (PLA). The fabricated objects were subsequently immersed in a photosensitive monomer solution and direct laser writing technique (DLW) was used to refine its inner structure by fabricating a fine mesh inside the previously produced scaffold. In addition, a composite material structure out of four different materials fabricated via DLW is presented. This technique, empowered by ultrafast lasers allows 3D structuring with high spatial resolution in a great variety of photosensitive materials. A composite scaffold made of distinct materials and periodicities is acquired after the development process used to wash out non-linked monomers. Another way to modify the 3D printed PLA surfaces was also demonstrated - ablation with femtosecond laser beam. Structure geometry on macro- to micro- scales could be finely tuned by combining these fabrication techniques. Such artificial 3D substrates could be used for cell growth or as biocompatible-biodegradable implants. To our best knowledge, this is the first experimental demonstration showing the creation of composite 3D scaffolds using convenient 3D printing combined with DLW. This combination of distinct material processing techniques enables rapid fabrication of diverse functional micro-featured and integrated devices. Hopefully, the proposed approach will find numerous applications in the field of tissue engineering, as well as in microelectromechanical systems, microfluidics, microoptics and others.