Facebook Patents ‘Small Form Factor’ AR Display With ‘Large Field of View’

by David Heaney • January 25th, 2019

Facebook won a patent for an augmented reality display “with small form factor, a large field of view, and a large eyebox”.

Current augmented reality displays either have a small field of view or small form factor- but not both. The Magic Leap One for example is relatively compact with a horizontal field of view of 40 degrees. Leap Motion’s Project North Star design achieves 100 degrees, but is significantly bulkier.

Just like all modern VR headsets on the market use the same display technique (lenses magnifying an LCD/OLED panel), all modern AR headsets use waveguides. For an explanation of how waveguides work, see this article by Chris Grayson.

Typical approaches to increase the field of view involve using a heavier material with a higher refractive index. Facebook’s technique uses decoupling elements on each side of the waveguide. The patent claims it provides a diagonal FoV of “at least 60 degrees”- 52 horizontal and 30 vertical. Multiple possible designs are presented, the seventh having 72 degrees diagonal.

facebook ar display patent

The patent could be related to the recent Business Insider report of a source’s hands on impression at Facebook. The source claimed to have tried a prototype that “resembled traditional glasses much more closely than the bulky AR headsets offered by Microsoft (the HoloLens) or Magic Leap.”

At Oculus Connect 5 Facebook Reality Labs Chief Scientist Michael Abrash expressed his priorities for AR hardware. At the top was social acceptability and low weight. A specific goal given was a weight of less than 70 grams. Engineering a display system that achieves a decent FoV without adding weight would be key to achieving this- and likely the research direction that led to this patent.

Microsoft likely isn’t resting on its laurels, however. Hololens 2 is expected to be revealed just next month, and the company invests heavily in AR research. Last year the company applied for a patent for a MEMS scanner based display with FoV of “around 70 degrees”.

It’s impossible to tell how far along Facebook and Microsoft are in commercializing these techniques. Companies patent many technologies that never make it to market. But combined with the Business Insider report, it does seem possible that progress is being made towards the AR glasses we all dream of one day owning.

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