An integrated hot embossing and thermal reflow method for precision manufacture of plano-convex glass microlens arrays

Plano-convex glass microlens arrays (MLAs) have broad applications in imaging, sensing, illumination, and communication systems. This paper proposed a three-step method to precision manufacture of plano-convex glass MLAs, which involves fabrication of SiC microhole arrays (MHAs), hot embossing of glass micropillar arrays (MPAs) and thermal reflow of glass MLAs. The effects of embossing temperature, force, and time on the replication accuracy of glass MPAs are evaluated. Subsequently, the glass MPAs with decent replication accuracy were subjected to thermal reflow experiments for studying the effects of reflowing temperature and reflowing time on the geometric features of formed glass MLAs. It is found that the height and tip curvature of reflowed glass microlenses can be controlled by adjusting the reflowing temperature and time. The warpage amplitudes and mean birefringence of most reflowed glass substrates are less than 5 μm and 27 nm/cm, respectively. Furthermore, the reflowed glass microlens arrays shows a decent uniformity in an area with a diameter of ∼4 mm. Finally, the feasibility of the integrated hot embossing and thermal reflow method in producing glass nano-lens arrays is also demonstrated. As a result, the hybrid forming technology that combines hot embossing with thermal reflow not only avoids the difficulties of fabrication of MLA and NLA mold inserts, but also possesses the advantages of high efficiency and low cost, which is expected to be a promising mass production technology for glass micro/nano-lens arrays.