热回流

Abstract(#br)In this paper, we present microlens arrays (MLA) with long focal length (in millimeter range) based on thermal reflow process. The focal length of microlens is usually in the same order of lens diameter or several hundred microns. To extend focal length, we made a photoresist (SU-8) MLA covered by a Polydimethylsiloxane (PDMS) film on a glass substrate. Because the refractive index difference between PDMS and photoresist interface is lower than that of air and MLA interface, light is less bended when passing through MLA and is focused at longer distance.

Optrodes是向神经元传递光的神经探针，其辐照度至少为1mW / mm2。微电致发光二极管( MicroLED，简称微发光二极管)采用微透镜对光进行准直，可以在不增加微LED功耗的前提下提高辐照度，减少脑部过热。本文给出了能够准直微LED发出光的PDMS (聚二甲基硅氧烷)微透镜的FEM (有限元方法)模拟，保证了平均辐照度为310mW / mm2。在模拟微透镜的基础上，采用微加工工艺制备了微透镜阵列。利用AFM (原子力显微镜)和SEM (扫描电镜)对所制备阵列的PDMS微透镜之一进行了实验表征。微透镜的平均表面粗糙度为2.3 nm，基底直径为80 μ m，高度为55 μ m。还可以利用高斯光学确定微透镜焦距( 96μm )、数值孔径( 0.42 )、f数( 1.2 )和焦深( 2.66μm )。验证了该制备工艺，即使采用PDMS / PDMS脱模，也未对负模进行表面处理。