Molding and hot forming techniques for fabricating plastic aspheric lenses with high blue-light transmittance
Molding and hot forming techniques for fabricating plastic aspheric lenses with high blue-light transmittance
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DOI：
10.1007/s00542-009-0936-9
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发表时间：
2010-08-01
影响因子：
2.1
通讯作者：
Shye, Der-Chi
中科院分区：
文献类型：
--
作者：
Hung, Kuo-Yung;Chen, Yi-Ko;Shye, Der-Chi
本文的目的是使用微电铸和热压技术作为替代高成本的精密切割或传统的注射成型在高蓝光透射率的塑料非球面透镜的制造。非球面透镜的阴模是由紫外光固化的SU-8聚合物通过静电吸引制成的。然而，SU-8的405 nm蓝光透射率仅为大约40- 50%，这不适合用于高密度光学拾取系统。因此，本文采用低应力、低表面粗糙度、镍微电铸和成型技术，并采用微热压系统，从COC塑料形成具有高蓝光透射率的非球面透镜（在405 nm处透射率为88%）。所得到的透镜具有约1 mm的通光孔径和约0.6的数值孔径。电铸模具具有通过AFM测量的约8 nm的粗糙度。通过白色光干涉仪（WYKO）测量，COC（n = 1.53）非球面透镜在热压印后的粗糙度为约146 nm（300 A μ m × 220 A μ m）。热压COC和原始SU-8（n = 1.67）非球面透镜的形状精度可以控制在约2.638%的误差。COC和原始SU-8非球面透镜的热压印光斑尺寸可以控制在约11%的误差。该误差应考虑材料折射率差和形状误差。还使用不同的压制温度和力测试粗糙度和斑点尺寸。这项技术可以开发用于制造蓝光405 nm微光学系统中的透镜。
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 the 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 technologies 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 0.6. The electroforming mold has a roughness of approximately 8 nm as measured by AFM. The roughness of COC (n = 1.53) aspheric lenses after hot-embossing is approximately 146 nm (300 A mu m x 220 A mu m) as measured by white light interferometer (WYKO). The shape precision of the hot-embossing COC and original SU-8 (n = 1.67) aspheric lenses can be controlled with approximately 2.638% error. The spot size of the hot-embossed COC and original SU-8 aspheric lenses can be controlled with approximately 11% error. This error should account for the material refractive index difference and the shape error. The roughness and spot size were also tested using different pressing temperatures and forces. This technology could be developed to fabricate lenses in Blu-Ray 405 nm micro-optical systems.