Abstract This paper is a review and analysis of the various implementation architectures of diffractive waveguide combiners for augmented reality (AR), mixed reality (MR) headsets, and smart glasses. Extended reality (XR) is another acronym frequently used to refer to all variants across the MR spectrum. Such devices have the potential to revolutionize how we work, communicate, travel, learn, teach, shop, and are entertained. Already, market analysts show very optimistic expectations on return on investment in MR, for both enterprise and consumer applications. Hardware architectures and technologies for AR and MR have made tremendous progress over the past five years, fueled by recent investment hype in start-ups and accelerated mergers and acquisitions by larger corporations. In order to meet such high market expectations, several challenges must be addressed: first, cementing primary use cases for each specific market segment and, second, achieving greater MR performance out of increasingly size-, weight-, cost- and power-constrained hardware. One such crucial component is the optical combiner. Combiners are often considered as critical optical elements in MR headsets, as they are the direct window to both the digital content and the real world for the user’s eyes. Two main pillars defining the MR experience are comfort and immersion. Comfort comes in various forms: – wearable comfort—reducing weight and size, pushing back the center of gravity, addressing thermal issues, and so on – visual comfort—providing accurate and natural 3-dimensional cues over a large field of view and a high angular resolution – vestibular comfort—providing stable and realistic virtual overlays that spatially agree with the user’s motion – social comfort—allowing for true eye contact, in a socially acceptable form factor. Immersion can be defined as the multisensory perceptual experience (including audio, display, gestures, haptics) that conveys to the user a sense of realism and envelopment. In order to effectively address both comfort and immersion challenges through improved hardware architectures and software developments, a deep understanding of the specific features and limitations of the human visual perception system is required. We emphasize the need for a human-centric optical design process, which would allow for the most comfortable headset design (wearable, visual, vestibular, and social comfort) without compromising the user’s sense of immersion (display, sensing, and interaction). Matching the specifics of the display architecture to the human visual perception system is key to bound the constraints of the hardware allowing for headset development and mass production at reasonable costs, while providing a delightful experience to the end user.

中文翻译：

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用于混合现实耳机的波导组合器：纳米光子学设计视角

摘要 本文回顾和分析了用于增强现实 (AR)、混合现实 (MR) 耳机和智能眼镜的衍射波导组合器的各种实现架构。扩展现实 (XR) 是另一个经常用于指代 MR 频谱中的所有变体的首字母缩略词。此类设备有可能彻底改变我们的工作、交流、旅行、学习、教学、购物和娱乐方式。市场分析师已经对企业和消费者应用程序的 MR 投资回报表现出非常乐观的预期。AR 和 MR 的硬件架构和技术在过去五年中取得了巨大进步，这得益于最近对初创企业的投资炒作和大公司加速的并购。为了满足如此高的市场预期，必须解决几个挑战：首先，巩固每个特定细分市场的主要用例，其次，通过越来越受尺寸、重量、成本和功率限制的硬件实现更高的 MR 性能。一个这样的关键组件是光组合器。合成器通常被认为是 MR 耳机中的关键光学元件，因为它们是用户眼睛通往数字内容和现实世界的直接窗口。定义 MR 体验的两大支柱是舒适度和沉浸感。舒适性有多种形式： – 穿戴舒适性——减轻重量和尺寸，推回重心，解决热问题，等等 – 视觉舒适度——在大视野和高角度分辨率上提供准确和自然的 3D 线索 – 前庭舒适度 – 提供稳定和逼真的虚拟覆盖，在空间上与用户的运动一致 – 社交舒适度 – 允许真实眼神接触，以社会可接受的形式因素。沉浸感可以定义为向用户传达真实感和包围感的多感官感知体验（包括音频、显示、手势、触觉）。为了通过改进的硬件架构和软件开发有效解决舒适度和沉浸感的挑战，需要深入了解人类视觉感知系统的具体特征和局限性。我们强调需要以人为本的光学设计流程，这将允许最舒适的耳机设计（可穿戴、视觉、前庭和社交舒适度），而不会影响用户的沉浸感（显示、感应和交互）。将显示架构的细节与人类视觉感知系统相匹配是限制硬件约束的关键，允许以合理的成本进行耳机开发和大规模生产，同时为最终用户提供愉快的体验。