固態熱致動可調變微透鏡之研究

Thermal Actuated Solid Tunable Micro Lens

李思源(Lee, SzYuan)

指導教授 ： 方維倫

國立清華大學/工學院/奈米工程與微系統研究所/博士(2009年)

摘要

光學透鏡是用來操控與調變”光”的主要工具。在微小化的需求下，傳統以多重鏡片加上複雜機構來進行焦距調變的方式已不再合適，因此，開發本身具調變能力的微透鏡就成為重要的研究課題。目前常見的三種可變焦微透鏡，都是由兩種以上的物質態組成，不易做到構造簡單可靠、製程單純相容性高、構型易於與其它光學元件整合這三項需求，無法滿足越來越多樣的微光學系統應用。本研究針對近期提出的固態熱致動可變焦微透鏡進行研究，探討具備上述三種特徵的PDMS微透鏡的調變與光學特性，並嘗試開發其在光學領域的其它可能性。本研究進行了以下三項實驗：（一）將透鏡加熱產生形變，藉此改變焦距，並進行機械與光學行為之模擬，依模擬結果設計元件參數與製程，並製作實物量測真實透鏡形貌與光學特性，驗證概念之可行性，另外，以MTF量測評估透鏡光學品質。（二）以簡易的製程，整合固態熱致動變焦微透鏡與振幅調變型/相位調變型Fresnel透鏡，並透過光學量測，證明合成之複合透鏡系統可提升系統數值孔徑，或具多重焦點的功能。（三）利用不對稱的導熱環設計，將固態熱致動變焦微透鏡轉變為具像散調變能力的系統，此設計是除適應性光學系統外，目前已知唯一作像散調變具備反轉子午面與弧矢面焦點先後位置的微系統。

關鍵字

熱致動 ； 微光機電 ； Fresnel lens ； 微透鏡 ； 微機電 ； 微光學

並列摘要

Rapid development MOEMS (Micro Opto-Electro Mechanical System) can be applied to variety fields, including optical communication, imaging, optical storage, industrial detection, and bio-detection. In response to the requirement of system miniaturization, optical component with tunability is favored than traditional moveable lens set. Currently, all designs of tunable lens are composed of two material states. That leads to complicated packaging issues which are impediment to system integration. The newly developed solid-state thermal actuated tunable lens is free from those problems and seems promising to verity applications. It employs thermal expansion to deform PDMS lens surface which further leads to focal length change. No moving parts, no special packing needs and friendly manufacture process make it being flexible to integrate with other optical components. In this study, we tried to further develop its merit. Three sets of experiment are designed and carried out. The first one simulated the actuating mechanism and corresponding optical behavior. Actual components are implemented and measured. The result verified the focal length tuning ability. A further measurement of MTF was also accomplished to understand its optical performance variation with respect to the focal length tuning. To demonstrate the easy integration of this tunable lens and optical components, different type of Fresnel lenses were integrated with tunable lens in the form of cemented doublet. Little extra effort was required to accomplish the integration, thanks to the friendly fabrication process of tunable lens. The optical functions of doublet were also verified successfully. In the third set of experiment, the flexibility of the tunable lens is demonstrated. The inner shape of conduction ring was designed to be ellipse which may leads to asymmetrical deformation at expansion and induce astigmatism. Simulation and optical measurement are in good agreement. In summary, the experiments demonstrate the flexibility and potential of solid-state thermal actuated tunable lens. It worth further study and have good chance to come close to the goal of efficient and reliable tunable device.

並列關鍵字

micro lens ； MOEMS ； thermal actuated ； tunable ； Fresnel lens ； MEMS

參考文獻

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