On the etching-free green manufacturing of large-area fused silica microlens arrays by 3D direct laser writing

While wet chemical etching is widely used to fabricate fused silica microlens arrays, achieving the green manufacturing of large-area and high precision microlens arrays is challenging, due to the involved strongly corrosive and toxic reagents, lengthy processing chain, and poor direct control over the final lens profile. In this work, we propose a dry direct laser writing strategy based on infinite field of view coordination to realize the green manufacturing of large-area fused silica microlens arrays, with the absence of wet chemical etching assistance. Specifically, a Gaussian filter-based trajectory decomposition algorithm with a constant resultant velocity constraint is established, so that long stroke mechanical stage motion and high dynamic response galvanometer motion can be coordinated during the layer-by-layer laser ablation-induced material removal. Compared with step scanning and mechanical scanning strategies, the proposed direct laser writing strategy not only significantly eliminates visible stitching defects, but also reduces the maximum profile deviation by 70.2% and 95.2%, and shortens processing time by 10.0% and 75.6%. Finally, large-area fused silica microlens arrays, containing 6400 lens units over 80 mm × 80 mm, are fabricated by the full-laser green manufacturing without visible stitching errors. The reported findings provide a technical green manufacturing route for large-area fused silica microlens arrays.