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Proceedings Paper

Development of ultraprecise injection molding method for thermoplasticlenses
Author(s): Akiro Fukushima; Motoaki Kawazu; Hidenori Ito; Hisaaki Koseko; Toshiharu Hatakeyama; Wataru Ohotani; Toshihiro Kanematsu
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Paper Abstract

We have developed a new method of injection molding (GATESEALTN injection molding method) for ultra-precise plastic lenses. Our method is summarized as follows: 1) The filling pressure is selected to make the pressure of the polymer the same as the atmospheric pressure at opening the mold, and the mold temperature at injection is higher than the glass transition temperature (Tg); 2) After injection filling and sealing the gate, the pressure and temperature of the polymer in the cavity are homogenized by keeping the temperature of the mold constant at above Tg; 3) The mold is gradually cooled down below the heat distortion temperature without any change in specific volume. The surface figure accuracy is a peak—to-valley roughness better than 0.3 im and a root mean square roughness better than 0.04 pm. The unique feature of our method is to control the temperature of the mold after injecting a constant weight of polymer into the cavity of constant volume. We are now mass—producing a wide range of thermoplastic lenses for optical systems by this new injection molding method.

Paper Details

Date Published: 20 October 1992
PDF: 10 pages
Proc. SPIE 1720, Intl Symp on Optical Fabrication, Testing, and Surface Evaluation, (20 October 1992); doi: 10.1117/12.132109
Show Author Affiliations
Akiro Fukushima, RICOH Co., Ltd. (Japan)
Motoaki Kawazu, RICOH Co., Ltd. (Japan)
Hidenori Ito, RICOH Co., Ltd. (Japan)
Hisaaki Koseko, RICOH Co., Ltd. (Japan)
Toshiharu Hatakeyama, RICOH Co., Ltd. (Japan)
Wataru Ohotani, RICOH Co., Ltd. (Japan)
Toshihiro Kanematsu, RICOH Co., Ltd. (Japan)

Published in SPIE Proceedings Vol. 1720:
Intl Symp on Optical Fabrication, Testing, and Surface Evaluation
Jumpei Tsujiuchi, Editor(s)

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