Fabrication of fused silica microlens arrays by gel casting and modulation of focal length by controlling gel solid content

This article presents a method for fabricating fused silica quasi-periodic microlens array (MLA) by gel casting and template transfer. While keeping slurry viscosity consistent, by precisely controlling polyvinyl alcohol (PVA) content to adjust solid content, which can alter sintering shrinkage and regulates microlens focal length. This study determined an appropriate viscosity threshold of 300 mPa·s. The green body can be transformed into a fused silica MLA by sintering in a vacuum atmosphere at 1300 °C for 30 min. Additionally, this study established a quantitative relationship between the PVA content and the characteristic dimensions of the microlens. After measuring the prepared multifocal microlens array (MF-MLA), it was found that by adjusting the PVA content, the focal length can vary in the range of −320.03 μm to −37.14 μm and −110.56 μm to −25.29 μm. This approach provides an efficient, adaptable, and environmentally friendly way for the production of fused silica micro-optical components.