Replication of precise polymeric microlens arrays combining ultra-precision diamond ball-end milling and micro injection molding

Abstract

A simple and novel combination of ultra-precision diamond ball-end milling and micro injection molding technique is described to produce precise microlens arrays out of polycarbonate (PC), polymethylmethacrylate (PMMA) as well as polystyrene (PS). The microlens arrays consist of 100 lenses in a 10 9 10 array with a lens radius of 273 lm, a lens diameter of 300 lm and a lens depth of 45 lm. Pitch between the lenses is fixed at 800 lm. The injection molding parameters were optimized to get precise microlens geometries with low surface roughness. The results show a precise diamond milled mold insert and injection molded microlens arrays with minor deviations in radius and surface roughness of the microlenses, particularly for microlens arrays out of PMMA.

Injection moulding of micropillar arrays: a comparison of poly(methyl methacrylate) and cyclic olefin copolymer

“…Poly(methyl methacrylate) (PMMA) is a polymer with good mechanical strength and optical properties and is suitable for manufacturing microfluidic devices by injection moulding (Ma et al 2020). The effect of moulding conditions on the replication of microfeatures on PMMA, including mould temperature, injection velocity (speed), injection pressure/time and packing pressure, have been investigated (Liou and Chen 2006;Chien 2006;Kirchberg et al 2012). Guided by numerical simulation, there also have been attempts to fabricate nanopillars with PMMA by injection moulding (Jiang et al 2016;Zhou et al 2018b).…”

Fabrication and Optical Characterization of Polymeric Aspherical Microlens Array Using Hot Embossing Technology

“…Besides, there are some problems including complicated processing steps, high cost, and low processing efficiency. Chen et al [14] and Kirchberg et al [15] used ultra-precision milling to process silicon-based molds combined with injection molding to process high-quality microlenses, but the processing cycle is too long. Chang et al [16] realized non-contact rapid rolling on the glass substrate based on the rolling technology and produced a microlens array with high surface quality; however, it is difficult to control each microlens' dimension accuracy.…”

Rapid fabrication of various molds for replication of polymer lens arrays

“…Hence, the development of a low‐cost, high‐efficiency method for the fabrication of various lens array molds is essential. Many precision manufacturing technologies for preparing lens array molds with different dimensions have been proposed and attempted, such as focused ion beam technology , three‐dimensional diffuser lithography , isotropic etching of glass masters , a combined thermal reflow and electroforming process , and ultra‐precision diamond milling . In addition, we have developed a technique combining photolithography and wet chemical etching for the fabrication of a thin stainless steel mold with a circular hole array pattern.…”