電控變焦液晶透鏡之特性探討

Abstract

我們探討電控變焦液晶透鏡的電光特性，其電控變焦的原理為利用一個從邊緣到中央漸弱的不均勻電場，使液晶旋轉排列成梯度分佈，產生空間中拋物線的折射率分佈，不同的電壓造成不同的拋物線曲度，達到透鏡變焦的效果。本論文首先介紹液晶材料的物理參數，接下來透過液晶透鏡的文獻，瞭解液晶透鏡的基本分類與圓孔電極液晶透鏡的歷史演進，並選擇最基礎的圓孔電極結構之液晶透鏡進行電控焦距、反應時間與溫度效應的探討，尤其是溫度效應在文獻上討論甚少。由實驗結果得知在25℃至60℃之間，可以利用溫度來改善反應時間，且不影響變焦範圍。

We study the electro-optic properties of electrically tunable-focusing liquid crystal (LC) lenses. A spatially inhomogeneous electric field which decreases gradually from the edge to the center makes the gradient-rotation distribution of LC molecules to produce parabolic distribution of refractive indices. The principle of electrically tunable-focusing is that the curvature of the distribution of refractive indices can be changed by applied voltages. In this thesis, we introduce the physical parameters of LC materials and survey literatures of LC lenses. Then, we select a LC lens with hole-patterned electrode to study the focal length, response time, and temperature effect of the LC lens. From the experimental results, we can improve the response time by increasing temperature and the focusing properties remain similiar between the temperature of 20℃ and 60℃.