Simulation and fabrication of poly methyl methacrylate infrared lenses

Infrared thermography is a promising solution that can help improve our lives. However, most of the common materials used to fabricate lenses, such as glass, are opaque in the infrared range. Silicon and germanium are better solutions. But shaping these two materials are truly complicated and time-consuming. Many research works have been devoted to develop cost-effective infrared lenses. Due to material restriction, traditional lenses to focus infrared light are expensive. On the other hand, we found that PMMA (Poly methyl methacrylate) is an ubiquitous polymer material. It is cheap and transparent in mid-IR range. More importantly, liquid PMMA can be shaped and solidified easily. Therefore, we chose PMMA as the material to design and make our IR lenses. In this paper, we choose PMMA and discuss its optical properties in mid-IR range. We believe that PMMA is a highly potential material for low-cost infrared lenses. Also, we show simulation results of an f/1.39, diameter = 11mm and focal length = 13.9mm Fresnel lens made by PMMA to demonstrate its feasibility. We made a PMMA Fresnel lens, by using MEMS processes and embossing. The experimental results agree well with simulation data.