A microlens array on curved substrates by 3D micro projection and reflow process
A microlens array on curved substrates by 3D micro projection and reflow process
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DOI：
10.1016/j.sna.2012.03.002
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发表时间：
2012-06
影响因子：
4.6
通讯作者：
Hao Zhang;Lei Li;D. L. McCray;D. Yao;A. Yi
中科院分区：
文献类型：
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作者：
Hao Zhang;Lei Li;D. L. McCray;D. Yao;A. Yi
微透镜阵列由于其在光学、电子和能源领域的广泛应用而变得越来越重要。目前，微透镜阵列的制造工艺主要是在平面基底上发展起来的。对于非平面基板，现有的制造方法存在各种缺点。这主要是由于与3D微结构制造工艺相关的固有技术复杂性。本文介绍了一种新颖的曲面微透镜阵列三维制作方法。为了制作微透镜阵列，采用曲面上的聚甲基丙烯酸甲酯微透镜阵列作为投影光学元件。在弯曲的镀钛铝基板上自旋涂覆一层厚的正光刻胶SPR 220。预先选择的图案通过使用自制的曝光系统投射到光刻胶上。在开发过程中，在弯曲的基板上产生了微圆柱体。然后对圆柱阵列进行热回流处理，形成微透镜阵列。对影响微透镜形状的因素进行了实验研究。这些影响因素包括薄膜厚度变化、曝光和显影变化、衬底坡度、高宽比和热回流过程中的加热时间。最后用Twyman-Green干涉仪对微透镜进行了测试。结果表明，通过对工艺参数的控制，获得了所需的微透镜形状。
Microlens arrays are becoming increasingly important because of their widespread applications in optical, electronic, and energy fields. Currently, microlens array fabrication processes are mainly developed on planar substrates. For nonplanar substrates, existing fabrication methods suffer from various disadvantages. This is largely due to the inherent technical complexity associated with 3D microstructure fabrication processes. In this study, an innovative 3D fabrication method for microlens arrays on curved surfaces is introduced. To fabricate the microlens array, a polymethylmethacrylate microlens array on a curved surface was used as projection optics. A thick layer of positive photoresist SPR 220 was spin coated on a curved, titanium-coated aluminum substrate. A pre-selected pattern was projected onto the photoresist by using a home built exposure system. The development process resulted in micro cylinders on the curved substrate. A thermal reflow process was then performed on the cylinder array to form the microlens array. Experiments were conducted to evaluate the factors that affect the shapes of the microlenses. These factors include film thickness variation, exposure and development variation, slope of the substrate, height to width ratio and heating time in thermal reflow process. Finally microlenses were tested using a Twyman–Green interferometer. Results showed that the required shape of the microlenses achieved by controlling the process parameters.