採用自由曲面透鏡之近眼光場顯示器設計

Abstract

在顯示技術與電腦科技日趨發達的現代，商業與個人的虛擬空間應用正逐漸地影響著人類的日常生活，如網路購物、雲端平台、視訊會議、網路遊戲等。如今，市面上越來越多商業產品開始陸續投入關於連接現實生活與虛擬空間的研究，而虛擬實境（virtual reality）以及擴增實境(augmented reality)的想法正是現實與虛擬空間結合的一種體現。隨著顯示技術的發展，將虛擬實境及擴增實境應用於頭戴式裝置的產品不斷推陳出新，未來頭戴式裝置將朝向輕薄化、廣視角、高解析度、即時的立體影像、提升觀賞舒適度等方向邁進，而這事實上也正是現今頭戴式裝置所面臨的問題。因此，本論文提出一新型近眼顯示器架構，採用光場(light field)資訊技術，可以達到輕薄、舒適等特性。 本研究中使用Sony 0.7” OLED作為顯示器，並以此規格做系統設計，探討不同參數間對成像品質的影響。我們首先提出一厚透鏡成像演算法(thick lens ray tracing)，以修正傳統薄透鏡演算法(pinhole ray tracing)在大視角所造成的影像位置追跡錯誤，以利於影像品質之提升與實際應用。之後為改善大視角影像模糊問題，設計一自由曲面微透鏡陣列，並對其成像品質、視角等進行分析，結果顯示與傳統使用球面微透鏡陣列的系統相比，在最高理論解析度不減少的情況下，有效視角可增為4.5倍。 我們成功設計出相比於傳統頭戴顯示器體積更輕薄的系統，且改善傳統光場顯示器在大視角影像模糊的問題。我們並對設計之微透鏡陣列做公差分析，以評估其生產之可行性，以期未來光場顯示系統廣泛應用於如教育、醫療訓練、娛樂遊戲、商業宣傳等多元領域。

In this high tech generation, virtual spaces for commercial and personal usage are now gradually affecting our daily lives through the connection with internet platform, like shopping, cloud, video conference, online games, and so on. Nowadays, there are more and more research and products that trying to build the bridge between real life and virtual space. Therefore, the idea of virtual reality and augmented reality is the outcome of connecting real world and virtual concepts. So far, whether immersing in the virtual world or moving the virtual image to the real word, head-mounted display has being continuously innovated. The next generation of head-mounted display should be light, equipped with wide viewing angle, high resolution, instant 3D image, and more comfortable user experience. In fact, these are the issues head mounted displays now encounter. Therefore, in this thesis, we proposed a new type of near eye display which apply light filed technology to achieve the features of light and simple structure and comfortable for wearing. We used Sony 0.7” OLED as the display in our research and designed the parameters for the system as well as discussed about how the different parameters would affect the imaging quality. We first proposed a thick lens ray tracing algorithm to correct the ray-tracing error of elemental image in traditional pinhole ray-tracing algorithm so as to enhance imaging quality and available to be applied in real situation. In the meantime, a freeform micro-lens array was designed to solve the blurry image issue at large field of view. We then did the analysis on imaging quality and field of view, etc. The results show that compared with the conventional system using spherical micro-lens array, the effective field of view in our system is 4.5 times larger under the premise that the highest theoretical resolution is not reduced. We successfully designed a lighter head mounted display compared with the conventional one and improved the blurry image issue in large field of view in conventional light field display. We also did the tolerance analysis to evaluate the probability of production. In the future, we wish to apply light field head mounted display to more areas such as education, medical training, entertainment, commercial and etc.