Plastic microlens arrays by deep lithography with protons: Fabrication and characterization

In this paper, we present the state-of-the-art of deep lithography with protons (DLP), a technology that we have adopted and optimized to rapidly prototype three-dimensional micro optical components and high-aspect-ratio micro mechanical structures in poly(methyl methacrylate). In particular, we focus on the fabrication of individual plastic refractive microlenses featuring a wide range of numerical apertures, diameters and pitches and on their 2-dimensional arrays. We provide a detailed description of the microlens fabrication technique and its calibration procedure. We highlight the quantitative geometrical and optical characteristics of these DLP microlenses and we demonstrate the reproducibility of their fabrication process. We also illustrate the prototyping flexibility of DLP by fabricating arrays featuring microlenses with different sags, pitches and diameters. As a conclusion, we analyze and discuss the strengths and weaknesses of this technology.