Laser-assisted direct roller imprinting of large-area microstructured optical surfaces  

作　　者：Keisuke Nagato Ken Takahashi Yuki Yajima Masayuki Nakao 

机构地区：[1]Department of Mechanical Engineering,Graduate School of Engineering,The University of Tokyo,7-3-1 Hongo,Bunkyo-ku,Tokyo 113-8656,Japan

出　　处：《Microsystems & Nanoengineering》2024年第1期257-266,共10页微系统与纳米工程（英文）

基　　金：supported by JSPS KAKENHI(grant number 24686019)from the Ministry of Education,Culture,Sports,Science,and Technology(MEXT),Japan.

摘　　要：In this study,a high-throughput fabrication method called laser-assisted direct roller imprinting(LADRI)was developed to lower the cost of nanoimprinting large-area polymer films and to address problems associated with nanoimprinting,namely,microstructural damage and precision in flatness of entire film.With LADRI,the laser directly heats the microstructured surface of the roller mold,which heats and melts the surface of a polymethyl methacrylate(PMMA)film to replicate the microstructures on the mold rapidly.In this study,the effects of laser power density,scanning speed,size of the microstructures,and contact pressure on the replication speed were investigated experimentally.The replication speed increased as the power and scanning speed increased.However,because the film required heating until it filled the entire depth of the microstructure,an appropriate replication speed was necessary.This result was supported by simulation of the temperature distribution inside the mold and the PMMA using transient heat conduction analyses.To demonstrate the applications of LADRI,two different optical surfaces were replicated:an antireflection(AR)structure with conical structures sized several hundred nanometers and a lightextraction structure with a microlens array(MLA)comprising 10μm lenses,for display and illumination,respectively.The replication degree of the MLA was governed by the contact pressure.Polymer flow simulation indicated that the heat conduction and flow speeds of the melted PMMA surface were comparable within several tens of micrometers.In addition,the reflectivity of the AR structure decreased from 4 to 0.5%,and the light intensity of the light-extraction structure increased by a factor of 1.47.

关 键 词：MICROSTRUCTURE ROLLER conduction 

分 类 号：O43[机械工程—光学工程]