Proceedings of the Korean Society for Technology of Plasticity Conference (한국소성가공학회:학술대회논문집)
- 2003.04a
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- Pages.7-13
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- 2003
Fabrication and Modeling of Microlens Array by a Modified LIGA Process
- Kim Dong Sung (Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH)) ;
- Lee Hyun Sup (Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH)) ;
- Yang Sang Sik (Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH)) ;
- Lee Bong-Kee (Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH)) ;
- Lee Sung-Keun (Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH)) ;
- Kwon Tai Hun (Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH)) ;
- Lee Seung S. (Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH))
- Published : 2003.04.01
Abstract
Microlens arrays were fabricated using a novel fabrication technology based on the exposure of a PMMA (Polymethylmethacrylate) sheet to deep X-rays and subsequent thermal treatment. X-ray irradiation causes the decrease of molecular weight of PMMA, which in turn decreases the glass transition temperature and consequently causes a net volume increase during the thermal cycle resulting in a swollen microlens. A new physical modeling and analyses for micro lens formation were presented according to experimental procedure. A simple analysis based on the new model is found to be capable of predicting the shapes of micro lens which depend on the thermal treatment. For the replication of micro lens arrays having various diameters with different foci on the same surface, the hot embossing and the microinjection molding processes has been successfully utilized with a mold insert that is fabricated by Ni-electroplating based on a PMMA microstructure of micro lenses. Fabricated microlenses showed good surface roughness with the order of 1nm.
Keywords
- Microlens array;
- Modified LIGA process;
- Glass transition temperature;
- Free volume theory;
- Hot embossing and Microinjection molding