以菲左干涉儀探討液態透鏡介面行為

Liquid-Liquid Interface Behavior of Liquid Lenses Measurement Using Fizeau Interferometer

張翊(Chang, Kevin)

指導教授 ： 葉哲良

國立清華大學/工學院/動力機械工程學系/碩士(2013年)

摘要

近年來，微型液態透鏡在微光學系統中發展了許多重要的應用。液態透鏡不似傳統的玻璃透鏡，液體具有可變形的特性使得液態透鏡具有無限的發展潛力。然而，由於缺乏對液態鏡頭的量測方法以及對液體特性的認識，使得鏡頭的設計和改進面臨了許多困難。
這項研究提出了一種液體透鏡的測量方法，作者利用菲索干涉儀測試了由兩種液體介質組成的液態鏡頭。為了使電場對液滴的作用機制有更多的了解，這項研究著重於液體鏡頭的液-液界面行為，因為此界面的行為會影響液體鏡頭的品質和運動特性。該干涉儀被設置成兩種模式：反射模式和穿透模式。在反射模式中，液體界面的形貌及行為可以根據量測到的干涉條紋描繪出來。而在穿透模式中，我們可以找出液體透鏡元件對參考標準鏡的離球像差。在這項研究中，我們示範了幾個對介電式液態透鏡的測量工作，其中包含在靜態條件和準靜態行為下的測量。在穩定狀態下，我們討論了液體透鏡的對稱性，平坦度以及光學表現。另一方面，當我們將液態透鏡操作在低頻率時，液滴會產生準靜態的振動。而這些振動行為因為輸入頻率可以被分為幾種不同的模態。在各模態下，可以找到幾個接近共振的特定頻率使觀測到的條紋變化相當明顯。而共振的振幅會隨著頻率增加而減少但節點數則會增加。
本研究所觀察到的液滴行為，雖然提供的資訊未盡完整，然而以此非接觸式的光學量測方法卻可以在未來提供液態透鏡研發的基礎及品質的鑑定。此外，這項研究提出了以干涉儀量測液-液界面的概念，進一步對於液滴靜穩態行為做出描述，此亦可提升微型光流體應用發展的潛力。

關鍵字

介電力 ； 液態透鏡 ； 液-液介面 ； 液滴振動 ； 干涉條紋

並列摘要

Liquid microlenses have emerged and played an important role in micro-optical systems in recent years. Compared to the conventional glass lenses, the liquid lenses have the deformable characteristic of liquids, which endows them unlimited potential of development. However, lack of measuring method on liquid lenses makes design and improvement difficult. In the present study, we demonstrate a measuring method using the Fizeau interferometer to characterize the dielectric liquid lenses consisting of two sample liquids. Furthermore, this study focuses on the behavior of liquid-liquid interface which may influence the quality and characteristic of dielectric liquid lenses.
Two modes were used in the measuring experiments: reflective mode and transmission mode. The reflective mode is used to measure the profile of liquid-liquid interface including the symmetry, flatness, and quasi-static oscillation of the liquid drop, while the transmission mode can characterize the lens off-sphere aberrations.
Some resonant frequencies were found in the presence of interferograms which are categorized into several modes at frequency below 500 Hz. When the drop oscillates, the number of nodal points and amplitude of ripple on the liquid-liquid interface at different frequencies were discussed.
The measured phenomena in the study might be incomplete but it could provide some insights for further development of dielectric liquid lens. In addition, this work shared an idea of measuring liquid-liquid interface, which might be served as a reference in advancing opto-fluid systems.

並列關鍵字

dielectric force ； liquid lens ； liquid-liquid interface ； droplet oscillation ； interferograms

參考文獻

[1] L Mateu, and F Moll, “Review of energy harvesting techniques and applications for microelectronics,” Proc. SPIE, 2005.

[2] L. Dong, A. K. Agarwal, D. J. Beebe, and H. Jiang, “Adaptive liquid microlenses activated by stimuli-responsive hydrogels,” Nature, pp. 551-554, 2006.

[3] Su Xu, Hongwen Ren, Yifan Liu, and Shin-Tson Wu, Fellow, “Dielectric liquid microlens with switchable negative and positive optical power,” IEEE, pp. 297-301, 2011.

[4] D. Y. Zhang, V. Lien, Y. Berdichevsky, J. Choi, and Y. H. Lo, “Fluidic adaptive lens with high focal length tunability,” Applied Physics Letters, pp. 3171-3172, 2003.

[5] J. Heikenfeld, and A. J. Steckl, “High-transmission electrowetting light valves,” Applied Physics Letters, 2005.