Novel "Holographic Glasses" Tech Could Make VR, AR Headsets as Small as Regular Eyeglasses
Designed to underpin a shift from bulky VR and AR headsets, these glasses float holographic images right before your eyes.
A team of researchers from Stanford University and NVIDIA has demonstrated the technology, which could underpin the next generation of virtual reality (VR) wearables: holographic Glasses, barely larger and heaver than prescription eyeglasses.
"Holographic Glasses are composed of a pupil-replicating waveguide, a spatial light modulator, and a geometric phase lens to create holographic images in a lightweight and thin form factor," the researchers explain of their creation. "The proposed design can deliver full-color 3D holographic images using an optical stack of 2.5 mm thickness."
The design is based around near-eye holography, and builds atop recent work in boosting the quality and reducing the computational complexity of real-time holography through artificial intelligence. The result: a pair of virtual reality glasses that are compact and lightweight enough, at just 60g (just over 2oz), for all-day use.
Using a phase-only spatial light modulator (SLM) and a waveguide designed for a minimal footprint, plus clever computation to work around the waveguide's limitations, the glasses create a 2D or 3D image, which appears to be in front of the wearer with a 22.8° field of view (FOV) and a 2.3mm eye box — though a bench-top prototype offered a 3.4mm eye box in exchange for a 16.1° FOV. By tracking the user's gaze and adjusting a mirror, meanwhile, the wearable variant extends its eye box to 8mm horizontally.
This, the team admits, is considerably smaller than conventional virtual or augmented reality displays — meaning users get a compact window into the virtual world, rather than an all-encompassing view. "The FOV was mainly limited by the size of the available SLM and the focal length of the GP lens," the team writes in defense of the prototype. "With a 2-inch SLM and a 15mm focal length GP lens, we could achieve a monocular FOV of up to 120°."
The team's work is available under open-access terms on the NVIDIA Research website following its presentation at the SIGGRAPH 2022 conference.