Investigation on deformation mechanism and filling behavior in precision glass molding of D-K9 microlens arrays

Precision glass molding (PGM) is a promising method for mass-producing planar microlens arrays (MLAs). However, it faces key challenges in achieving uniform sub-lens filling and minimizing residual stress, which significantly limit optical performance and manufacturing yield. This study employs a finite element simulation to optimize process parameters and reveal the mechanisms behind uneven material deformation. We found that a double convex preform is better than a cylindrical one, as its initial point contact promotes coordinated shear deformation, resolving the insufficient edge filling. Parametric optimization shows that combining "higher temperature and lower velocity" during processing effectively reduces initial stress, ensuring stable lens profile accuracy. This approach explicitly improves uniformity and minimizes localized shear stress at the array edge. Additionally, stress relaxation and viscoelastic retraction are key mechanisms during the hold stage, with significant profile changes occurring within the first 25 seconds. Precision glass molding of the designed equi-double convex preform was performed using optimized parameters. The resulting microlens array exhibited filling rate higher than 91% and a surface roughness of less than 4 nm, effectively validating the accuracy of the simulation model. These findings clarify meaningful mechanistic relationships and provide manufacturers with a practical framework for large-scale production of high-uniformity MLAs.