Researchers Find Way To Shrink a VR Headset Down To Normal Glasses Size

Researchers from Stanford University and Nvidia have teamed up to help develop VR glasses that look a lot more like regular spectacles. PC Gamer reports: "A major barrier to widespread adoption of VR technology, however, is the bulky form factor of existing VR displays and the discomfort associated with that," the research paper published at Siggraph 2022 says. These aptly named "Holographic Glasses" can deliver a full-colour 3D holographic image using optics that are only 2.5mm thick. Compared to the traditional way a VR headset works, in which a lens magnifies a smaller display some distance away from it, shrinking all the prerequisite parts down to such a small size is quite the spectacular step forward for VR. The Holographic Glasses prototype uses pancake lenses, which is a concept that has been thrown around a couple of times in the past few years. These pancake lenses not only allow for a much smaller profile but reportedly they have a few other benefits, too: the resolution they can offer is said to be unlimited, meaning you can crank up the resolution for VR headsets, and they offer a much wider field of view at up to 200 degrees. [...] The research paper lists the glasses as such: "a coherent light source that is coupled into a pupil-replicating waveguide, which provides the illumination for a phase-only SLM that is mounted on the waveguide in front of the user's eye. This SLM creates a small image behind the device, which is magnified by a thin geometric phase (GP) lens." Though, it's very much a promise of what's to come more than an immediately shippable product today. There are some limitations: while there's scope to have a much higher FOV than current generation VR headsets, this particular wearable prototype only offered an FOV of 22.8 degrees. The benchtop prototype offered even less, at only 16.1 degrees. "[The FOV] is far smaller than commercially available VR/AR displays. However, the FOV was mainly limited by the size of the available SLM and the focal length of the GP lens, both of which could be improved with different components," the researchers say. Another limitation is the likely requirement for a very accurate measurement of the user's pupil, which won't be easy without a well-thought-out design. It would be possible to use an infrared gaze tracker to do this, the researchers note, but you'd need to be able to track the wearer's pupil size constantly as they will adjust often to different light conditions while using the glasses.

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