在球面上應用多次翻模製造之聚二甲基矽氧烷微透鏡陣列

Abstract

昆蟲的複眼是由幾千到幾萬個小眼所組合而成，其優點為能提供廣大的視角以及偵測高速的動作。因此，和傳統平面式光學元件相比，複眼式光學元件被應用在廣視角成像系統中，能大幅減少透鏡數目以及系統體積。然而傳統製程技術皆屬於平面製程，使得在曲面上製作微結構變得困難。在本篇論文中，我們提出一種在球面上製作微透鏡陣列的方法。利用熱回流製造緊密排列的微透鏡陣列，再用多次翻模技術將平面轉製成球面，製程的中間產物包含了凹面微透鏡陣列的曲面模具，這使得曲面型微透鏡陣列可以很容易地被大量複製。我們使用聚二甲基矽氧烷做為模具和透鏡的材料，由於液態的聚二甲基矽氧烷具有良好的覆蓋性，固化後具有彈性且對可見光波段的穿透度高，因此很適合用作微透鏡陣列的複製材料。實驗結果對曲面型微透鏡陣列進行分析，並和其他不同製程方法相比較。這種方法提供了簡單且低成本的曲面微透鏡製程。

An insect’s compound eye may consist of thousands of ommatidia. It allows wide field of view and can detect fast movement. Therefore, compared to traditional planar optical devices, compound-eye structured optical elements can reduce components and volume when being applied to compact imaging system. However, fabrication process for microstructures on curvilinear surface has a lot of difficulties since traditional fabrication techniques are planar. In this thesis, we present a method to fabricate microlenses on spherical surface. Microlenses with high fill factor were formed by thermal reflow technique, followed by multiple replication processes to transfer the microlenses from planar substrate onto spherical surface. During the process, we made a curved mold with concave microlenses, which allowed this method to be duplicable easily. Polydimethylsiloxane (PDMS) elastomer was employed as the material of both microlenses and mold. Because of the good coverability of liquid PDMS and the flexiblility and transparency for visible light after curing, PDMS is suitable for the replication process. The experimental results of curved microlens arrays were analyzed and compared with the other fabrication methods. This method provides a simple and low-cost fabrication process.