Glass multifocal microlens array through laser-induced topological transformation

We investigate the use of laser-induced topological transformation for manufacturing multifocal lens arrays with arbitrary focal ranges. Cylindrical preforms manufactured by femtosecond laser and chemical etching are topologically transformed into plano-convex lenses by thermally induced viscous flow and surface tension. In situ focal distance monitoring is employed to regulate the optical properties of the lens during its formation, enabling precise control over the final microlens topology regardless of process uncertainties. This approach also provides design flexibility, allowing lenses with varying focal lengths to be created from the same simple and identical preform. We also implemented a modeling framework to predict the time-dependent volume transformation. To illustrate the process capability, we demonstrate a microlens array made of lenses with multiple focal distances for which we characterize the optical performances.