虛擬現實（VR）為用家提供了一個結合了人工場境和現實世界的練習環境。隨著在醫療，軍事和娛樂行業日益增長的需求，虛擬現實化的設備將會越來越受歡迎。頭戴式顯示器（HMD）是一種利用自由曲面的光學棱鏡，以投射由微型顯示器顯示的圖像，讓用家能夠在近距離觀看和體驗虛擬環境的產品。 / 頭戴式顯示器由兩個基本部分組成，液晶顯示屏和一個光學元件，以能夠在很短的距離顯示圖像到用家的眼睛。光學自由曲面棱鏡在HMD研究中是一個主要的課題。設計的棱鏡需要運用大多數的光學理論和一些商業光學設計軟件的輔助。在市場，只有有限的光學軟件能深入地協助設計光學元件和系統。同時，成本高昂和不容易使用的光學軟件令到光學設計並不普及的原因。在下面的部分將用光學軟件ZEMAX去驗證每個設計。 / 自由曲面棱鏡的幾何形狀設計是為構建一個頭盔顯示器的關鍵問題。通常情況下，頭盔內自由曲面棱鏡由三面特別設計的非球面表面而組成。源圖像經過三個非球面反映後，可參照圖6，將圖像投射到人類視網膜上而形成圖像。棱鏡上的三個面的互相協調將是一個具有挑戰性的問題。 / 跟據現有的產品和研究分析，研發了一種新風格的棱鏡。在這篇論文中，由射線追踪和光學理論的幫忙，建議了一款凸-平棱鏡作HMD上的光學棱鏡。利用光學設計軟件分析和優化以追求一個可穿戴和低像差的光學棱鏡作目標。光學棱鏡中有兩個面為平面，因此光線能在棱鏡中穩步地轉化，從而，降低光學系統的像差。製作了經優化表面定位的原型，雖然原型是成本低，但它們比半透明的鏡子有一個更好的分辨率。在新設計的一個HMD上，一個廣闊和清晰的圖像將顯示。 / Virtual reality (VR) provides an artificial environment to user for practicing under a synthetic environment which merges the real world with artificial scene. In response to the growing demand in medical, military and entertaining application, devices that can simulate VR will become more and more popular. Head mounted display (HMD) is a kind of wearable products that utilize freeform optical prisms to project images generated by microdisplays, enabling users to situate in virtual environments. / HMD has two basic components, a LCD and an optical element, to display image to naked eye in a short distance. An optical freeform prism will be a main research topic in HMD. To design the prism will require substantial knowledge in optical theory and the aid of some commercial optical design software. In the market, there is limited number of software for in depth optical analysis. Meanwhile, costly and not user-friendly software is a problem of unpopularity of optical design. Zemax has been used for verifying the each design in the below sections. / The design of geometric shape for the freeform prism is crucial for constructing a HMD. Typically, the freeform prisms inside HMD comprise of 3 specially designed aspherical surfaces. The source image is reflected by those three surfaces to form image on human retina. The interplay of three surfaces will is the main challenging problem. With the analysis of existing products and researches, a new-style prism is proposed. In this thesis, with the aid of ray tracing and optical theory, a convex-plano prism is developed. / Analyses of optical design software and optimization are utilized to pursue the goal of wearable and low aberration HMD optical prism. Prototypes with the optimized surfaces alignment are fabricated. With two flat surfaces on the prism, the rays translate steadily in the prism. Hence, the optical system’s aberration is reduced. Although the prototypes are low cost, they have a better resolution than half-transparent mirror. Also a wide and clear image will show on the new style see-through HMD. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Ho, Pui Lam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 57-59). / Abstracts also in Chinese. / Abstract --- p.i / Abstract (Chinese) 摘要 --- p.iii / Acknowledgement --- p.iv / List of Figure and Table --- p.vii / Paper published --- p.xi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview on Near Eye Display (NED) --- p.1 / Chapter 1.2 --- Literature Review on HMD --- p.1 / Chapter 1.3 --- Motivation and Research Objective --- p.7 / Chapter 1.4 --- Thesis Outline --- p.8 / Chapter Chapter 2 --- Fundamental Design Concept --- p.9 / Chapter 2.1 --- Prism --- p.9 / Chapter 2.2 --- Convex Lens --- p.11 / Chapter 2.3 --- Combination of Convex lens and Regular Prism --- p.12 / Chapter Chapter 3 --- Optical Design Analysis by Software Package --- p.16 / Chapter 3.1 --- Surface Alignment --- p.16 / Chapter 3.2 --- Distortion --- p.18 / Chapter 3.3 --- MTF --- p.19 / Chapter 3.4 --- Image Simulation --- p.20 / Chapter 3.5 --- Aberration analysis --- p.21 / Chapter 3.6 --- Aspherical surface --- p.22 / Chapter Chapter 4 --- Design Principle and Procedure --- p.26 / Chapter 4.1 --- Basic Criteria --- p.26 / Chapter 4.2 --- See-throughPurpose --- p.27 / Chapter 4.3 --- Material --- p.28 / Chapter 4.4 --- SurfacesAlignment --- p.29 / Chapter 4.5 --- Compensator --- p.30 / Chapter 4.6 --- Angle Alignment --- p.30 / Chapter Chapter 5 --- System Efficiency --- p.32 / Chapter 5.1 --- System Efficiency --- p.32 / Chapter 5.2 --- System Analysis --- p.35 / Chapter Chapter 6 --- Prototype Fabrication and Testing --- p.38 / Chapter 6.1 --- Display System --- p.38 / Chapter 6.2 --- Monocular Configurations --- p.39 / Chapter 6.3 --- Prototypes Building --- p.40 / Chapter 6.4 --- Advantages --- p.54 / Chapter 6.5 --- Limitation --- p.54 / Chapter Chapter 7 --- Conclusions and Future Work --- p.55 / Chapter 7.1 --- Conclusions --- p.55 / Chapter 7.2 --- Future work --- p.55 / Reference --- p.57 / Appendix --- p.60 / Chapter Appendix 1 --- Background Theory --- p.60 / Chapter A1.1 --- Optical Theory --- p.60 / Chapter A1.2 --- Matrix Method --- p.65 / Chapter A1.3 --- Human Vision --- p.66 / Chapter Appendix 2 --- Simulation of reflection --- p.67 / Chapter Appendix 3 --- Aberration analysis of prisms --- p.70 / Chapter Appendix 4 --- Specification --- p.71