Waveguides for Mixed Reality: Principles and Applications

Level: Intermediate Length: 4 hours Format: In-Person Lecture Intended Audience: This course has been prepared for university or industry researchers working with Mixed Reality hardware. It is also helpful to team leaders managing an MR hardware team and human vision researchers who want to understand the capabilities and limitations of the technology. The course assumes the attendees have a first degree in Physics, Engineering, Maths or related subjects and basic optics and vector geometry knowledge. Description: The future Mixed Reality headset will undoubtedly use waveguides to achieve a spectacle form factor and, if required, optical see-through. Mixed Reality waveguides were unheard of ten years ago, but now they receive billions of dollars in investment. Therefore, while there is a plethora of marketing information online, there is limited information on their theory of operation. This course presents the operating principles of diffractive and reflective waveguides and gives examples of their use in existing MR products. The gratings theory is described for diffractive waveguides, emphasizing the k-space representation. The different grating technologies are then presented, including Volume Bragg Gratings (VBGs), Surface Relief Gratings (SRGs), and Polarization Gratings. Reflective waveguides are described, including their manufacturing methods, advantages over diffractive waveguides, and shortcomings. Finally, the operation of a few existing waveguide-based headsets is described. Learning Outcomes: This course will enable you to: - describe how a waveguide is used to make an HMD, differentiate between its function as a combiner and an exit pupil expander and explain the purpose of the display engine - list the different kinds of waveguides - describe in k-space, how the rays propagate from the display engine to the user’s eye - describe the Bragg condition and how it is applied in thin and thick holograms. - compute the diffraction angle (and efficiency) from a volume Bragg grating - describe the basic principle of RCWA - describe and analyze the light path in space in a waveguide-based HMD - describe the basic operation of some existing waveguide-based AR displays Instructor(s): Andreas Georgiou has been working in Mixed Reality optics for more than a decade. Before that, he worked in medical imaging and space instrumentation. Optical engineer by training, Andreas is particularly interested in diffractive and computational optics and their applications in head mounded displays, three-dimensional displays, and sensors. Currently, he is a Principal Researcher at Microsoft Research and a Fellow at Robinson College, University of Cambridge. He obtained his Ph.D. in diffractive optics from the University of Cambridge. Event: SPIE Photonics West 2024 Course Held: 29 January 2024