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  • 學位論文

微製程技術與光學系統之整合設計與應用:有機可形變面鏡與微透鏡陣列

Design and Fabrication of Compact Optical Devices:Organic Deformable Mirror and Microlens Arrays

指導教授 : 蘇國棟

摘要


在本篇論文中,我們利用微製程技術發展並製作一個有機可形變面鏡 (organic deformable mirror) 和一個微透鏡陣列 (microlens array),並展現整合此二元件和一般光學元件後,用來發展微小光學系統的潛力。 發展有機可形變面鏡的過程中,我們利用聚亞醯銨 (polyimide) 來製作一具高度可撓性的薄膜,使薄膜具有低的楊氏系數 (Young’s modulus, 小於10 GPa ) 和低的殘餘應力 (residual stress, 藉由挑選和基板之熱膨脹係數符合的薄膜材質可小於5 MPa),薄膜表面鍍有鋁用以反射或聚焦入射的光線,藉由施加在薄膜(鋁)和下電極間的電壓,可使此有機可形變面鏡因為靜電力吸引而下凹產生曲率,並藉此電壓來控制其度數 (diopter, m-1),製作出來的有機可形變面鏡有低驅動電壓和大位移量的特性 (約只需150伏特的電壓,即可達到20-diopters),這使得此有機可形變面鏡有些特殊的應用,例如,在本篇論文中,我們用它製作一兩百萬畫素的薄型自動對焦鏡頭模組;另外,我們也推導出一個解析的模型來預測,當使用不同材料來做有機可形變面鏡時,特定鏡面度數下所需施加電壓的大小。除此之外,我們利用馬達驅動的位移平台、顯微鏡和自動對焦的演算法 (Tenengrad) ,發展了一套自動系統,用以量測製作出來的有機可形變面鏡之楊氏系數和殘餘應力。 在微透鏡陣列的發展過程中,我們提出了兩個製程技術用以提升微透鏡陣列的特性。其一是“邊界局限法”,此方法可以製作出同時具有高填充率和小半徑曲率特性的微透鏡陣列。實驗結果顯示,每個微透鏡的高度是22 μm直徑是48 μm而間距只有2 μm,我們也可以藉由這個方式來製作具有隨機曲率分布的微透鏡陣列;另一技術是透過PDMS覆蓋層來增加微透陣列的焦距,一般來說,由熱回熔(thermal reflow) 技術做出的微透鏡陣列,因受限於熔化光阻和基板間的接觸角,焦距長度有一定的限制,此技術可使直徑240 μm的微透鏡之焦長延長至2.1 mm (約原本的三倍),這兩個方法使我們在設計微透鏡時有更多的彈性。 最後,我們希望這篇文章可以啟發相關的研究人員,並對後續的發展有些許貢獻。

並列摘要


We demonstrated the potential of wafer level optical components for compact optical systems by developing two micro optical components: organic deformable mirror (DM) and microlens arrays (MLA) which was fabricated by MEMS technology. In the development of organic deformable mirror, we fabricated a highly flexible polyimide membrane which has low Young’s modulus (<10 GPa) and low residual stress (<5 MPa, by choosing the CTE of membrane material, which matches to a silicon substrate). The incident light is reflected or focused by the Aluminum coating layer on the membrane. The optical power (diopter, m-1) of DM is curved and controlled by the gap-closing force results from the applied voltage between membrane (Aluminum coating) and bottom electrode pad. This polymer DM has advantages on large stroke and low applied voltage (~150 V achieved 20-diopters, lower voltage is possible). The fabricated DM could be integrated with other optical components for imaging applications. We show a thin 2M-pixels camera module with autofocus (AF) facility provided by DM rather than voice coil motor (VCM). The object position of clear image varies from 4 cm to infinity. In addition, we derived an analytic model, which predicts the optical power with required applied voltage according the material properties of membrane. Besides, an automatic system for measurement on Young’s modulus and residual stress was developed and implemented by a motorized stage, optical microscope, and image processing algorithm (Tenengrad). In microlens process, we developed two fabrication techniques. One is “boundary-confined method” which achieves high fill factor and small radius of curvature or high numerical aperture (NA) simultaneously. The height of microlens is 22 μm and the diameter is 48 μm, and the gap is 2 μm. In addition, the various curvature distribution (VCD) over microlenses in a MLA could be made based on this method. The other technique in microlens process extends the focal length of microlens by a covering Polydimethylsiloxane (PDMS) layer. The focal length of microlens with 240 μm diameter is extended to around 2.1 mm or 3 times larger than origin. It is longer than the maximum focal length of microlens, which is limited by the contact angle of photoresist and substrate in thermal reflow process. Therefore, designer could have more flexibility on the MLA design for specific applications. Finally, we believe this integration on MEMS technology and optical systems could inspire the researchers to develop compact and convenient optical systems which might benefit to the human.

參考文獻


[7] R. F. Fischer and B. Tadic, Optical System Design: McGraw-Hill, 2000.
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[3] H. Peng, Y. L. Ho, X.-J. Yu, M. Wong, and H.-S. Kwok, "Coupling efficiency enhancement in organic light-emitting devices using microlens array - Theory and experiment," IEEE/OSA Journal of Display Technology, vol. 1, pp. 278-282, 2005.

被引用紀錄


周宜賢(2011)。應用基因演算法於微透鏡陣列製程最佳化之研究〔碩士論文,國立臺北科技大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0006-1807201117014900

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