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Industrial High-precision 3D Printing via two-photon absorption (TPA) as a potential disruptive tool for microfabrication enables novel products for diverse applications in the field of optics, photonics, biomedicine, and life sciences. Especially the freedom in design provides one-step fabrication of structures that are not feasible with conventional fabrication techniques or need combined technologies with a required changeover of the workpiece.
Up to now, 2PP-fabrication has only been used in the community for structures on the micro and mesoscale due to limited travelling ranges of the translation stages and the field-of-view (FoV) of microscope objectives in combination with galvoscanners to deflect the laser instead of moving the sample relative to the focus. Macroscale elements can be realized via stitching strategies but, however, often induce obvious joints that hinder aimed applications. For this purpose, different fabrication strategies for large scale elements are revealed in this contribution without relying on stitching. Modular machine configurations like inverted focusing through a bath of photoresist (LithoBath3D) enable objects several millimeters in size with micrometer resolution. Additionally, 3D scanning by translation stages only can be efficiently used for the fabrication of large scale DOE structures. For optical elements with high surface quality, precise fabrication is required. As galvoscanners enable high throughput at several 100 mm/s scan speed, TPA-fabricated microlenses are limited to the FoV of the corresponding microscope objective, typically less than 0.5 mm. This limit can be overcome by sophisticated exposure strategies like a synchronized movement of translation stages and galvoscanner (infinite FoV) in combination with advanced beam steering.
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