光場擴增實境眼鏡之鳥盆式目鏡設計

Abstract

近年來，元宇宙、擴增實境等新興科技受到了廣泛的關注。然而，大多數市面上的擴增實境眼鏡都存在視覺輻輳調節衝突(vergence-accommodation conflict)的問題，這是導致用戶容易感到視覺不適或眼睛疲勞的原因，而光場顯示器則被認為是解決 VAC 問題的最佳方法。在本文中，我們提出了一種鳥盆式(birdbath)目鏡設計，可與PetaRay Inc.生產的光場投影模組配合使用，作為近眼光場擴增實境眼鏡的一部分。該目鏡具有 30 度的視場(FOV) 和長景深(DOF)，同時整個系統能夠保持在一般眼鏡的尺寸大小範圍。更重要的是，這款目鏡能夠將光場投射模組產生的光場完全投射到眼睛中，使不同深度上的虛擬物體都能夠被正確感知。不同於一般設計，此目鏡的主要目的是以緊湊的光學系統尺寸達到傳遞光場的效果，因此，機械結構、視場和景深這三項參數是此目鏡設計的主要考量。我們分析了這些關鍵參數之間的權衡及其對光場擴增實境系統的影響，並導出整體的結構限制和優化策略。這種具有特殊設計規格的目鏡能顯著提升視覺舒適度(visual comfort) ，非常適合擴增實境光場眼鏡之應用。

In recent years, metaverse and augmented reality (AR) have received considerable attention. However, most conventional AR displays suffer from the vergence-accommodation conflict (VAC) that is the root cause of visual discomfort or eyestrain for users. It is commonly believed that light field display is the ultimate device for metaverse because it can resolve the VAC problem. In this work, we propose a birdbath eyepiece to work with the light field projection module produced by PetaRay Inc. as part of a compact near-eye light field augmented reality (AR) glasses, which has a 30 degrees field of view (FOV) and a long depth of field (DOF). More importantly, this eyepiece is capable of receiving the light field from the light field projection module and projecting it fully into the eye, allowing virtual objects at different depths to be properly perceived. The eyepiece is designed based on the purpose of delivering the light field with compact frame size, so the mechanical structure, DOF, and FOV are the three parameters that we particularly emphasize in this work. The tradeoff between these key parameters and their impact on the light field AR system is analyzed, while the structural constraints and optimization strategy according to the analysis are also described in detail. The specially designed specification of the eyepiece makes it well suited for the light field projection module, significantly advancing the visual comfort of AR glasses.