Meta shows 3 millimeter thin holographic VR display
Researchers at Meta Reality Labs and Stanford University have presented a new type of display that enables ultra-compact VR glasses.
The holographic VR display in its raw form.
(Image: Stanford University / Meta Reality Labs Research)
A prototype for a new type of display that enables ultra-compact VR glasses has been presented by researchers from Meta Reality Labs and Stanford University. It combines a holographic waveguide with an AI model that ensures high 3D image quality. The result is an ultra-thin VR display with a large eyebox and the ability to naturally focus on multiple image planes. The entire optical structure is less than three millimetres thick.
Meta is building on earlier research work: Back in 2020, the company presented a holographic VR display with a sunglasses form factor. However, this older prototype was nine millimetres thick, limited to the color green and had a smaller eyebox. The researchers describe the new system as a decisive milestone on the way to practical holographic near-field displays.
Holographic displays: a beacon of hope with a catch
Current VR headsets are still large and heavy and can only display a single focal plane. This can lead to headaches and eye pain because, unlike in the real world, the eye cannot focus on close objects in a natural way. In research, this problem is referred to as a vergence-accommodation conflict.
(Image:Â Meta Reality Labs Research)
The overarching goal of Meta's display research is a system that allows natural focusing while overcoming the bulky design of conventional optics. The result is VR goggles that live up to their name.
In a study published in Nature Photonics, the researchers present a solution based on holographic waveguides. Displays of this type could theoretically achieve the aforementioned goals, but they come with their own dilemma: holographic waveguides can be used to achieve either high 3D image quality or a large eyebox, but not both at the same time.
To explain: the eyebox describes the volume within which the pupil can move without the image becoming blurred. The larger the eyebox, the more tolerant the VR display reacts to positional deviations of the eye, a decisive factor for the user-friendliness of VR headsets.
AI helped with the breakthrough
The researchers managed to circumvent these dilemmas and combine high 3D image quality with a large eyebox. Their trick is to direct laser light into the optical system at many slightly different angles to create a large eyebox from many small viewing zones. You can imagine it like a small flashlight shining through a window from different directions. Together, this creates a larger eyebox in which the eye can move around and still see the complete image.
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But this is only part of the solution. To ensure high 3D image quality, the researchers trained an AI model that takes into account the construction of the optical system and the properties of the light within it. The holographic computer graphics, which allow natural focusing, are generated on the basis of this model. Thanks to the AI-supported corrections, these images appear sharp and spatial across the entire eyebox.
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The current disadvantages of the system include a frame rate of 60 Hertz, which is low by VR standards, and a relatively narrow diagonal field of view of 38 degrees.
Early research, not a product prototype
The research prototype shows the direction in which VR displays could develop in the long term. It primarily serves as a proof of concept and was not developed with a view to short-term commercialization. It remains to be seen when such a technology would really be ready for use: The distance to today's display technology, which is rather conventional in comparison, is too great.
(Image:Â Meta Reality Labs Research)
Meta demonstrated a fully functional PC VR prototype with holographic lenses in 2022 and also made it clear that considerable effort would still be required to develop a practicable laser for the system. And this is just one of many components for which Meta would have to create its own production capacities and supply chains should the company decide to rely on holographic displays.
In any case, the new prototype would not be quite as compact as shown in the pictures because it lacks the central components of VR glasses, above all a tracking system. If the entire technology is to be housed in a self-sufficient device, a processor, a battery and a suitable cooling solution will also be required. A fundamental change would also be required on the software side: a new rendering pipeline would be needed to generate holographic computer graphics. So there is still a long way to go from futuristic prototype to finished product.
The research work is freely accessible on the Internet.
(kbe)
