Fabrication of micro-lens array with antireflection structure

Abstract Optical lens performance is hindered by reflections from the lens surface. Thus, there is a need for antireflection structures (ARSs) for optical lenses. A typical antireflection film is multilayered. There are two drawbacks of using multilayer films: they require complex manufacturing processes and the films do not suppress the reflection of incident light. Herein, we focused on single films with moth-eye structures to achieve low reflectance over a wide range of wavelengths and incident angles. The moth-eye structure is used for anti-reflection films and can be easily fabricated by ultraviolet nanoimprint lithography (UV-NIL). In a previous study, we formed ARSs on complex substrates, such as aspheric lenses, by the reverse replica mold method. In this study, we fabricated the reverse replica mold using two micro-lens arrays, which investigated the limited minimum scale applicable for the flexible mold in order to use the reverse process as previously reported. We considered changing to heat-resistant resin. As a result, we were able to investigate the compliance limits of flexible molds. In addition, we successfully fabricated an ARS on the micro-lens array by using a reverse replica mold and the previous process. However, fabrication was not possible using OrmoClear resin. Therefore, we undertook a process of forming the micro-lens array and ARS with a single resin instead of using the reverse replica mold process. This process was similar to injection molding. As a result, we successfully fabricated the micro-lens array combined with the ARS by using OrmoClear. This micro-lens array with ARS maintained its nanopatterns after heating for 30 min at 250 °C. This process is suitable for fabricating a micro-lens array.