新型電極應用於高聚焦品質之大孔徑液晶透鏡設計與實驗驗證

Abstract

本論文研製新型液晶可變焦透鏡，除了利用電壓改變焦距以外，並設計新型上電極圖樣，包含環形及多層並增加一組外加電壓調節，大幅改善液晶透鏡因增大孔徑造成折射率不如完美聚焦之折射率分佈，藉此新型透鏡改善聚焦品質，以利於與手機或其他成像系統模組化。由於傳統基本型液晶透鏡有效聚焦孔徑若要超過直徑2 mm以上則會因折射率分佈如梯形，造成中央大部分平整區域無法聚焦，僅邊緣部分聚焦。而此新型液晶透鏡設計另一組外加電極改善非均勻電場分佈如我們所預期，此電極依據漸變式折射率透鏡之折射率分佈而設計，利用2DIMOS模擬軟體模擬電場與折射率分佈，轉換成焦距長度及驗證焦距變化之效果。並以實體量測與驗證新型液晶透鏡之焦距變化及光學聚焦品質。

This study is devoted to analyze and improve the performance of the liquid crystal (LC) lens with variable focusing length. An LC lens with hole-and-ring and multi-layered electrodes are designed in this study. The proposed electrode design aims to improve the optical performance of LC lens especially in the large aperture. The designed LC lens is suitable for being implemented in a camera module in a cell phone. For traditional single-hole type LC lens, the generated electric filed fails to form desired index distribution in the central region of the lens for effective large-aperture. It is found that when the effective aperture is larger than 2mm, the refractive index distribution is not formed in a uniform, parabolic-like shape. This study, therefore, designs a compensation thin ring and multi-layered ITO patterns inside of 4mm hole-patterned electrode for improving the intensity of electric field and also the distribution of index of refraction of LC lens for better focusing effects. Although the added ring or multi-layered pattern leads a non-uniform electric field, the effective focal length, one important performance index of the LC lens, is shorten under the same applied voltage.