## 3 Results
### Characterization of DLW 3D Lithography Produced Structures  
RB and 3D microporous woodpile structures obtained via DLW 3D lithography out of AESO and ASEO/VDM1 were characterized. These plant-derived resins were laser polymerized using ultrashort pulses by multiphoton absorption and avalanche induced cross-linking [54; 55]. Scanning Electron Microscopy (SEM) images are shown in Figure 7. Figure 7a demonstrates RB--five columns with five straight lines perpendicular to the column long edges. Figure 7b shows a close up view of RB from the top. \(P\) was set to 0.6 mW (2 TW/cm\({}^{2}\)) for the lines and each line was scanned with a different velocity \(v\), varying from 2 mm/s to 6 mm/s. It can be seen that each line has a slightly different width: the higher the \(v\), the narrower the line. Further 3D microporous woodpile structures were formed. Arrays of 75 \(\times\) 75 \(\upmu\)m\({}^{2}\) woodpiles are demonstrated in Figure 7c,e. In both cases, \(v\) was set to 5 mm/s and \(P\) was varied in the range of 0.4-1 mW (1.3-3.3 TW/cm\({}^{2}\)). It can be seen that an increased laser power \(P\) higher than \(d_{xy}\) can be used. Finally, the mm scale woodpiles were fabricated. Figure 7d shows a 1065 \(\times\) 1065 \(\upmu\)m\({}^{2}\) woodpile with a 75 \(\upmu\)m period and 4 layers, \(v\) = 5 mm/s, \(P\) = 0.4 mW (1.3 TW/cm\({}^{2}\)). However, it did not sustain itself due to the low mechanical rigidity. Figure 7f demonstrates a 1095 \(\times\) 1095 \(\upmu\)m\({}^{2}\) woodpile with a 120 \(\upmu\)m period and 6 layers, \(v\) = 5 mm/s, \(P\) = 0.6 mW (2 TW/cm\({}^{2}\)). The structure sustained itself and had a 3D architecture. To sum up, AESO and the resin AESO/VDM1 can be the great candidates as new renewable materials for DLW 3D lithography technology [56]. It has a wide working window ranging \(P\) from 0.1 mW to 1 mW (dynamic fabrication window aspect ratio 10 times). Spatial features of 1 \(\upmu\)m and a 6900 voxels/second throughput was achieved as a method for the evaluation of normalized \(\upmu\)-3D fabrication throughput [57]. We note that the possibility to the photosructure without the use of photoinitiators is not limited to serial direct write (DLW/SLA), but also can be extended to projection DLP lithography (SLM/DMD based) if the peak exposure intensity is sustained (for current case of employed material and light source the ranging within \(\approx\) 1-3 TW/cm\({}^{2}\)).  
It is envisaged that the photosructuring without the photoinitiators is beneficial for the fields of biomedicine, micro-optics and nanophotonics. The avoidance of toxic photoinitiators increases the integrity of biodegradable cell-growth scaffolds and reduces the auto-fluorescence while performing microscopy in vitro or in vivo. The absorbing materials are detrimental for the use in micro-optics and nanophotonics due to their reduced optical resilience and induced signal losses [58]. Moreover, the use of plant-derived materials in such technologies would benefit greatly due to their low toxicity, high biodegradability, and improved recycling options. Finally, it would reduce the dependency on limited and increasingly expensive fossil resources as well as greenhouse gas emission, which are the targets of the European Commission initiated \"Europe 2020\" strategy.