Optical Architectures for Augmented-, Virtual-, and Mixed-Reality Headsets

ISBN-13: 9781510634336

Bernard Kress

Opis

This book is a timely review of the various optical architectures, display technologies, and building blocks for modern consumer, enterprise, and defense head-mounted displays for various applications, including smart glasses, smart eyewear, and virtual-reality, augmented-reality, and mixed-reality headsets. Special attention is paid to the facets of the human perception system and the need for a human-centric optical design process that allows for the most comfortable headset that does not compromise the user's experience. Major challenges--from wearability and visual comfort to sensory and display immersion--must be overcome to meet market analyst expectations, and the book reviews the most appropriate optical technologies to address such challenges, as well as the latest product implementations.

Spis treści

• 1 Introduction
• Word of Caution for the Rigorous Optical Engineer
• 2 Maturity Levels of the AR/VR/MR/Smart-Glasses Markets
• 3 The Emergence of MR as the Next Computing Platform
• 3.1 Today's Mixed-Reality Check
• 4 Keys to the Ultimate MR Experience
• 4.1 Wearable, Vestibular, Visual, and Social Comfort
• 4.2 Display Immersion
• 4.3 Presence
• 5 Human Factors
• 5.1 The Human Visual System
• 5.1.1 Line of sight and optical axis
• 5.1.2 Lateral and longitudinal chromatic aberrations
• 5.1.3 Visual acuity
• 5.1.4 Stereo acuity and stereo disparity
• 5.1.5 Eye model
• 5.1.6 Specifics of the human-vision FOV
• 5.2 Adapting Display Hardware to the Human Visual System
• 5.3 Perceived Angular Resolution, FOV, and Color Uniformity
• 6 Optical Specifications Driving AR/VR Architecture and Technology Choices
• 6.1 Display System
• 6.2 Eyebox
• 6.3 Eye Relief and Vertex Distance
• 6.4 Reconciling the Eye Box and Eye Relief
• 6.5 Field of View
• 6.6 Pupil Swim
• 6.7 Display Immersion
• 6.8 Stereo Overlap
• 6.9 Brightness: Luminance and Illuminance
• 6.10 Eye Safety Regulations
• 6.11 Angular Resolution
• 6.12 Foveated Rendering and Optical Foveation
• 7 Functional Optical Building Blocks of an MR Headset
• 7.1 Display Engine
• 7.1.1 Panel display systems
• 7.1.2 Increasing the angular resolution in the time domain
• 7.1.3 Parasitic display effects: screen door, aliasing, motion blur, and Mura effects
• 7.1.4 Scanning display systems
• 7.1.5 Diffractive display systems
• 7.2 Display Illumination Architectures
• 7.3 Display Engine Optical Architectures
• 7.4 Combiner Optics and Exit Pupil Expansion
• 8 Invariants in HMD Optical Systems, and Strategies to Overcome Them
• 8.1 Mechanical IPD Adjustment
• 8.2 Pupil Expansion
• 8.3 Exit Pupil Replication
• 8.4 Gaze-Contingent Exit Pupil Steering
• 8.5 Exit Pupil Tiling
• 8.6 Gaze-Contingent Collimation Lens Movement
• 8.7 Exit Pupil Switching
• 9 Roadmap for VR Headset Optics
• 9.1 Hardware Architecture Migration
• 9.2 Display Technology Migration
• 9.3 Optical Technology Migration
• 10 Digital See-Through VR Headsets
• 11 Free-Space Combiners
• 11.1 Flat Half-Tone Combiners
• 11.2 Single Large Curved-Visor Combiners
• 11.3 Air Birdbath Combiners
• 11.4 Cemented Birdbath–Prism Combiners
• 11.5 See-Around Prim Combiners
• 11.6 Single Reflector Combiners for Smart Glasses
• 11.7 Off-Axis Multiple Reflectors Combiners
• 11.8 Hybrid Optical Element Combiners
• 11.9 Pupil Expansion Schemes in MEMS-Based Free-Space Combiners
• 11.10 Summary of Free-Space Combiner Architectures
• 11.11 Compact, Wide-FOV See-Through Shell Displays
• 12 Freeform TIR Prism Combiners
• 12.1 Single-TIR-Bounce Prism Combiners
• 12.2 Multiple-TIR-Bounce Prism Combiners
• 13 Manufacturing Techniques for Free-Space Combiner Optics
• 13.1 Ophthalmic Lens Manufacturing
• 13.2 Freeform Diamond Turning and Injection Molding
• 13.3 UV Casting Process
• 13.4 Additive Manufacturing of Optical Elements
• 13.5 Surface Figures for Lens Parts Used in AR Imaging
• 14 Waveguide Combiners
• 14.1 Curved Waveguide Combiners and Single Exit Pupil
• 14.2 Continuum from Flat to Curved Waveguides and Extractor Mirrors
• 14.3 One-Dimensional Eyebox Expansion
• 14.4 Two-Dimensional Eyebox Expansion
• 14.5 Display Engine Requirements for 1D or 2D EPE Waveguides
• 14.6 Choosing the Right Waveguide Coupler Technology
• 14.6.1 Refractive/reflective coupler elements
• 14.6.2 Diffractive/holographic coupler elements
• 14.6.3 Achromatic coupler technologies
• 14.6.4 Summary of waveguide coupler technologies
• 15 Design and Modeling of Optical Waveguide Combiners
• 15.1 Waveguide Coupler Design, Optimization, and Modeling
• 15.1.1 Coupler/light interaction model
• 15.1.2 Increasing FOV by using the illumination spectrum
• 15.1.3 Increasing FOV by optimizing grating coupler parameters
• 15.1.4 Using dynamic couplers to increase waveguide combiner functionality
• 15.2 High-Level Waveguide-Combiner Design
• 15.2.1 Choosing the waveguide coupler layout architecture
• 15.2.2 Building a uniform eyebox
• 15.2.3 Spectral spread compensation in diffractive waveguide combiners
• 15.2.4 Field spread in waveguide combiners
• 15.2.5 Focus spread in waveguide combiners
• 15.2.6 Polarization conversion in diffractive waveguide combiners
• 15.2.7 Propagating full-color images in the waveguide combiner over a maximum FOV
• 15.2.8 Waveguide-coupler lateral geometries
• 15.2.9 Reducing the number of plates for full-color display over the maximum allowed FOV
• 16 Manufacturing Techniques for Waveguide Combiners
• 16.1 Wafer-Scale Micro- and Nano-Optics Origination
• 16.1.1 Interference lithography
• 16.1.2 Multilevel, direct-write, and grayscale optical lithography
• 16.1.3 Proportional ion beam etching
• 16.2 Wafer-Scale Optics Mass Replication
• 17 Smart Contact Lenses and Beyond
• 17.1 From VR Headsets to Smart Eyewear and Intra-ocular Lenses
• 17.2 Contact Lens Sensor Architectures
• 17.3 Contact Lens Display Architectures
• 17.4 Smart Contact Lens Fabrication Techniques
• 17.5 Smart Contact Lens Challenges
• 18 Vergence-Accommodation Conflict Mitigation
• 18.1 VAC Mismatch in Fixed-Focus Immersive Displays
• 18.1.1 Focus rivalry and VAC
• 18.2 Management of VAC for Comfortable 3D Visual Experience
• 18.2.1 Stereo disparity and the horopter circle
• 18.3 Arm's-Length Display Interactions
• 18.4 Focus Tuning through Display or Lens Movement
• 18.5 Focus Tuning with Micro-Lens Arrays
• 18.6 Binary Focus Switch
• 18.7 Varifocal and Multifocal Display Architectures
• 18.8 Pin Light Arrays for NTE Display
• 18.9 Retinal Scan Displays for NTE Display
• 18.10 Light Field Displays
• 18.11 Digital Holographic Displays for NTE Display
• 19 Occlusions
• 19.1 Hologram Occlusion
• 19.2 Pixel Occlusion, or ""Hard-Edge Occlusion""
• 19.3 Pixelated Dimming, or ""Soft-Edge Occlusion""
• 20 Peripheral Display Architectures
• 21 Vision Prescription Integration
• 21.1 Refraction Correction for Audio-Only Smart Glasses
• 21.2 Refraction Correction in VR Headsets
• 21.3 Refraction Correction in Monocular Smart Eyewear
• 21.4 Refraction Correction in Binocular AR Headsets
• 21.5 Super Vision in See-Through Mode
• 22 Sensor Fusion in MR Headsets
• 22.1 Sensors for Spatial Mapping
• 22.2.1 Stereo cameras
• 22.2.2 Structured-light sensors
• 22.2.3 Time-of-flight sensors
• 22.3 Head Trackers and 6DOF
• 22.4 Motion-to-Photon Latency and Late-Stage Reprojection
• 22.5 SLAM and Spatial Anchors
• 22.6 Eye, Gaze, Pupil, and Vergence Trackers
• 22.7 Hand-Gesture Sensors
• 22.8 Other Critical Hardware Requirements
• Conclusion