Research of Molding Process for Fabricating High TransmittanceBlu-Ray Plastic Aspheric Lens

• Main Authors: CHEN, YU-CHUAN, 陳昱銓
• Other Authors: Kuo-Yung Hung
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/32950846634825353161

碩士 === 明志科技大學 === 機電工程研究所 === 97 === The purpose of this paper is to use micro-electroforming and hot-embossing technology as an alternative to high-cost precision cutting or traditional injection molding, in the fabrication of plastic aspheric lenses with high blu-ray transmittance. The female dies for aspheric lenses are fabricated from UV-cured SU-8 polymer via electrostatic attraction. However, SU-8 has a 405 nm blu-ray transmittance of only roughly 40-50%, which is not appropriate for use in high-density optical pickup systems. This paper, therefore, uses low-stress, low surface roughness, nickel micro-electroforming and molding technology, and employs a micro hot-embossing system, to form aspheric lenses with high blu-ray transmittance from COC plastic (transmittance: 88% at 405 nm).The resulting lenses have a clear aperture of approximately 1 mm, and a numerical aperture of roughly 0.65.The electroforming mold has a roughness of approximately 8 nm by AFM. The roughness of the COC aspheric lenses after hot-embossing is good by AFM. The shape precision of the hot-pressed COC aspheric lens and original SU-8 aspheric lenses can be controlled with approximately 2.6% error. The spot size of the hot-pressed COC and original SU-8 aspheric lenses can be controlled with approximately 11% error. Roughness and spot size were also tested using different pressing temperatures and forces. If this technology can be successfully developed, it would be possible to circumvent the poor blue light transmittance of SU-8 polymer and produce lenses that can be used in blu-ray DVD micro-optical systems.