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Proceedings of CAD'14, 2014, 55-57
Compensation of Shape Change of Amorphous Carbon Mold for Glass Molded Fresnel Lens
Jonghyun Ju, Youngkyu Kim, Seok-min Kim, Chung-Ang University
Abstract. Fresnel lens is commonly used as a primary optics for concentrator photovoltaic (CPV) system to concentrate the sunlight onto solar cells due to its thin and lightweight characteristics. Although an injection molded polymethylmethacrylate (PMMA) Fresnel lens and silicone on glass (SOG) Fresnel lens have been commercially available in the CPV industry, these Fresnel lens fabrication methods have long-term durability problems. A glass molded Fresnel lens can be a suitable solution for primary optics of CPV system, however, conventional glass molded Fresnel lens using precision ground tungsten-carbide (WC) mold could show lower optical efficiency due to the relatively large groove tip radius of precision ground WC mold. A method to fabricate amorphous carbon (AC) mold for glass molded Fresnel lens which have sharp tip radius was developed by the our recently developed AC mold fabrication process using replication and carbonization process of furan precursor. Fig. 1 shows the schematics of proposed fabrication method of AC mold for glass molded Fresnel lens. A nickel master pattern which had the negative shape of Fresnel lens was machined by precision diamond turning process. To fabricate AC mold, a Polydimethylsiloxane(PDMS) template was replicated from the nickel master and a mixture of furan resin was poured on the PDMS template.
Keywords. Shrinkage compensation, amorphous carbon mold, pyrolysis, glass Fresnel lens, concentrator photovoltaic