利用親水性質發展之自組式微透鏡與以離子導電高分子金屬複合物製備之低致動電壓可形變面鏡

Self-assembly microlens by hydrophilic effect and low actuation-voltage deformable mirror by ionic polymer metallic composite

魏祥鈞(Hsiang-Chun Wei)

指導教授 ： 蘇國棟

國立臺灣大學/電機資訊學院/光電工程學研究所/博士(2011年)

https://doi.org/10.6342/NTU.2011.02017

摘要

在本篇論文中，我們的研究涵蓋了兩大主題，分別為微透鏡陣列(microlens array)以及可形變面鏡(deformable mirror)。經由整合此二元件與一般光學元件後，發展光學系統於不同的應用。
自組式微透鏡陣列(self-assemble microlens array)，利用了紫外線臭氧清潔機將SU-8負型光阻表面改質，產生週期性排列的親水性區域，再利用表面張力將稀釋過後的SU-8光阻自行聚集在此親水性區域之中，進而形成球面的液態平凸透鏡，最後經由紫外光的固化後成了固體的微透鏡陣列。SU-8光阻具有良好的化學穩定性及機械強度，其光學吸收率非常低，加上基板使用的是透明玻璃，所以製作出來的微透鏡陣列是穿透式的，不須要再另外經過翻模的方式來製作，大幅簡化了製作的流程及減少製程時間。此方法具有低成本、低溫、省時之特點。另外，SU-8光阻本身是極性材料，藉由外加的電場可以增加表面的曲率，藉此進一步可以產生更短焦距的微透鏡，同時也使表面的粗糙度降低，提高其光學性質。同時，使用這種方法，我們可以精準地將微透鏡製作在發光二極體(LED)上，提高提取效率並增加發散角。另外，藉由實驗室發展的雙層熱回流式長焦長微透鏡陣列，我們發展了更為靈敏、動態範圍更廣的薛克-哈特曼波前感測器(Shack-Hartmann wavefront sensor)，同時針對長焦距及短焦距的影響與商用的感測器做比較。
我們利用了實驗室發展的微機電有機可形變面鏡 (micro electro mechanical systems organic deformable mirror)，配合光學鏡頭元件設計了可變對焦平面的光學模組，搭配Tenengrad影像處理方法及百分率降幅方法(percentage drop method)組成的自動對焦演算方法，成功地完成自動對焦光學模組。由於微機電有機可形變面鏡的驅動電壓較高(約150伏特)，所以我們進而採用了高分子致動器-離子導電高分子金屬複合物(ionic-conductive polymer metal composite, IPMC)，其具有低致動電壓與大位移量的特性。我們藉由發展此材料的灰盒子理論，搭配ANSYS有限元素分析軟體，設計了齒輪狀的離子導電高分子金屬複合物可形變面鏡(gear shaped IPMC DM)，其特點為低致動電壓及較廣的焦距變化。同時由於其可雙向致動的特性，可製作出同時具有聚焦及散焦能力的可形變面鏡。
最後，我們希望此篇論文可以啟發相關的研究，並對後續的發展有些許貢獻。

關鍵字

微透鏡 ； SU-8光阻 ； 親水性 ； 波前感測器 ； 可形變面鏡 ； 離子導電高分子金屬複合物

並列摘要

In this dissertation, there are two major topics of microlens array (MLA) and deformable mirror (DM). By integrating these two components and ordinary optical component, we developed different optics system in different applications.
Self-assembled microlens array was fabricated by hydrophilic effect using Ultraviolet (UV)/ozone modification on glass substrate. The modification on SU-8 photoresist produced periodic array of hydrophilic areas on the surface by the use of shadow mask. Afterwards, the substrate was dipped in and out of diluted SU-8 photoresist. Therefore, the liquid self-assembled MLA was formed. Finally, the solid MLA was cured by UV light. SU-8 photoresist has good chemical and mechanical strength, so it is suitable for MLA. Besides, the fabricated MLA is transparent so that there has no need for etch transferring. It decreases the process complexity a lot. Meanwhile, because of the polar molecular of SU-8 photoresist, the curvature of the microlens can be enlarged by applying external electric field. The surface roughness could be improved as well. This method provides a low cost, low time consumption, no etch transfer, low temperature, and no photo lithography method to fabricate MLA. We applied this method to fabricated microlens on a light emitting diode (LED) chip with precisely alignment. That improved the extraction efficiency and increased the viewing angle. Besides, we developed a more sensitive and larger dynamic ranged Shack-Hartmann wavefront sensor by using the developed long focal length MLA using double layer thermal reflow method. We also compared it with the commercial product.
We developed a thin autofocus camera module by using the developed micro electro mechanical systems (MEMS) organic deformable mirror (DM). It included a focus-varying optical system, and autofocus algorithm using Tenengrad image sharpness function and percentage-drop method. Besides, because of the high actuation voltage (~150 V), we adopt an ionic-conductive polymer composite to fabricate DM. IPMC is a polymer actuator with the advantage of low actuation voltage and large displacement. We built a simplified grey box model and simulate the deformation shape by using finite element method software, ANSYSR. A gear shaped IPMC DM was designed and demonstrated. It had the advantage of low actuation voltage and large optical power. Meanwhile, because of the bi-directional deformation ability, the DM with both positive and negative optical power was achieved.
Finally, we believe these research topics could inspire the related researchers and might have some benefit to the human.

並列關鍵字

microlens array ； SU-8 photoresist ； hydrophilic ； wavefront sensor ； deformable mirror ； ionic-conductive polymer metal composite

參考文獻

[1] H. Ottevaere, R. Cox, H. P. Herzig, T. Miyashita, K. Naessens, M. Taghizadeh, R. Volkel, H. J. Woo, and H. Thienpont, “Comparing Glass and Plastic Refractive Microlenses Fabricated with Different Technologies,” J. Opt. A: Pure Appl. Opt., vol. 8, pp. 407-429. (2006)

[2] Z. D. Popovic, R. A. Sprague, and G. A. Neville Connell, “Technique for Monolithic Fabrication of Microlens Arrays,” Applied Optics, vol. 27, no. 7, pp. 1281-1284. (1988)

[3] D. Daly, R. F. Stevens, M. C. Hutley, and N. Davies, “The Manufacture of Microlenses by Melting Photoresist,” Meas. Sci. Technol, vol. 1, pp. 759-766. (1990)

[4] T. R. Jay et al, “Preshaping Photoresist for Refractive Microlens Fabrication,” Opt. Eng., vol. 33, pp. 3552-3555. (1994)

[5] H. Ottevaere, B. Volckaerts, J. Lamprecht, A. Hermanne, I. Veretennicoff, and H. Thienpont, “2D Plastic Microlens Arrays by Deep Lithography with Protons: Fabrication and Characterization,” J. Opt. A: Pure Appl. Opt., vol. 4, pp. 22-28. (2002)