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.

Table of Contents:
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