Formation of 3D Free‐Form Artificial Compound Eye Mold by Maskless Discrete Wet‐Etching on Flat Fused Silica

Abstract Wet‐etching assisted by ultrafast laser for fabricating artificial comound eye (ACE) molds on hard materials has been under development for a decade. However, traditional methods have focused on simple‐shaped base molds, making it a significant challenge to integrate ommatidia molds onto complex base molds in a highly efficient and low‐cost manner. In this work, maskless discrete wet‐etching (MDWE) technique is introduced to fabricate 3D free‐form ACE molds on flat silica glass. These 3D free‐form ACE molds are fabricated via one‐step wet‐etching of discrete modification line arrays induced by picosecond laser direct writing. The discrete element arrays determine the morphology of the base mold, while each element controls the morphology of individual ommatidia molds. To achieve precise and flexible control of ACE molds, their formation rates and precision are investigated. These results show that the formation processes of the base mold significantly depend on geometric features, such as microtips and rounding morphologies. Empirical formulas are also established for controlling the diameter and radius of curvature of ommatidia molds. Using MDWE technique, free‐form ACE molds are successfully fabricated, demonstrating that it offers a precise, flexible, and efficient approach for integrating double‐scale structures, such as free‐form ACE molds.