Facile and flexible fabrication of gapless microlens arrays using a femtosecond laser microfabrication and replication process

We demonstrate a facile and flexible method to fabricate close-packed microlens arrays (MLAs). Glass molding templates with concave structures are produced by a femtosecond (fs)-laser point-by-point exposures followed by a chemical treatment, and convex MLAs are subsequently replicated on Poly(methyl methacrylate) [PMMA] using a hot embossing system. As an example, a microlens array (MLA) with 60-μm rectangular-shaped spherical microlenses is fabricated. Optical performances of the MLAs, such as focusing and imaging properties are tested, and the results demonstrate the uniformity and smooth surfaces of the MLA. We also demonstrated that the shape and alignment of the arrays could be controlled by different parameters.