Open AccessReplication of thermoplastic polymer spherical lens array using microforged molding technique
Author(s) -
Dan Xie,
Xiao Chang,
Xiayun Shu,
Jian Wang,
Lifang Mei,
Shanming Luo
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.030264
Subject(s) - materials science , lens (geology) , molding (decorative) , mold , optics , thermoplastic , composite material , fabrication , focal length , microlens , replication (statistics) , surface roughness , medicine , statistics , physics , alternative medicine , mathematics , pathology
In this paper, we propose a replication method of thermoplastic polymer spherical lens array using a novel microforged mold. The Si 3 N 4 ceramic balls, with 3.5 mm diameter, 10 nm surface roughness and 84 nm deviation from spherical profile, were utilized as indentor to generate aluminum alloy lens array mold. Upon the optimization of technical parameters, such as heating and de-molding temperature, indentation force and holding time, a high quality spherical lens array mold was obtained. The mold was used to fabricate spherical PMMA lens array by hot embossing, which showed excellent characteristics on dimensional stability, surface features and optical performances. Especially for the requirements of deep sag height and low f/#, the microforging technique reveals superior performance for low cost and high quality manufacture of spherical lenses. Compared to the previous complicated tools which requires precise calibration, the self-alignment mode of the balls and cavities can easily guarantee positioning accuracy. Accordingly, the pre-milled spherical cavity deformed uniformly in the process of microforging due to the symmetrical distribution of contact pressure and reduced the error caused by deformation. We believe the proposed microforging technique is an ideal mass production approach to the fabrication of thermoplastic polymer spherical lens array.