The importance of virtual reality (VR) headsets isn’t lost on anyone. Most certainly not Meta, formerly Facebook. The tech giant’s VR display research is focusing on building a new tech stack that includes the Varifocal technology that improves focus, has distortion correction ability to reduce effects such as warping and well as higher resolutions and High Dynamic Range (HDR) technology for VR.
“We estimate that getting to 20/20 vision across the full human field of view would take more than 8K resolution,” said Mark Zuckerberg, chief executive officer of Meta, during a select media briefing. The human vision, and the way it works, will not view all of those pixels in an 8K virtual reality content all the time across the entire field of view.
Yet, this will be a higher resolution than any display panel (this will include TVs and monitors) that is currently available for consumers.
Meta’s current VR headset prototypes include the Half Dome Series, Butterscotch, Starburst, Holocake 2 and Mirror Lake. Meta hopes the varifocal technology will underline improvements in its next-generation VR headsets. Meta said that in a study where users had the option to turn on varifocal technology on their prototype VR headsets or operate it in fixed mode, a majority opted for varifocal. It leads to less fatigue, elimination of blurry vision and sharper detailing, particularly of the smaller-sized objects in the frame.
“Once we had this feedback, the team put all their energy into getting the size and weight down and expanding the field of view. And the series of prototypes that they built, which we call Half Dome, ended up using fully electronic varifocal based on liquid crystal lenses, which are much smaller,” said Zuckerberg. He underlined that this was still very much work in progress, with optimizations still needed for the varifocal hardware and improvements in the reliability of eye-tracking.
The Butterscotch prototype, for instance, is perhaps a prime example of the technological advancements Meta research is focusing on. “Butterscotch is the latest and the most advanced of our retinal resolution prototypes and it creates the experience of near retinal resolution in VR. It is 55 pixels per degree, that’s about two and a half times the resolution of the Quest 2,” said Michael Abrash, chief scientist at Reality Labs, for Meta.
The resolution that the headset supports by default allows wearers to read (the eyesight permitting) to read the 20/20 vision line on an eye chart, via the VR headset. These are the same charts used for testing eyesight before prescribing glasses. This development, once it makes its way to consumer headsets, will allow VR products to match TVs and displays with up to 8K displays.
Distortion is a fairly common limitation of VR headsets, irrespective of the size, type and power. One of the reasons for this is that the algorithms for VR image processing (particularly as a human eye scans the different directions of a frame) are static. This is where dynamic image corrections, as the human eye moves around, are needed.
“To address that, what the team did was they built a distortion simulator that uses virtual objects and eye-tracking to replicate the distortion you would see for a headset for a given optics design, and display it using 3D TV technology,” said Abrash.
“So this allows the team to study different optical designs and distortion correction algorithms without needing to build an actual headset. The team has been able to explore dynamic distortion correction in literally minutes rather than months.”
Meta also gave a first peek at the Holocake 2 headset, labelled as the thinnest and lightest headset they’ve ever made.
By their very nature, VR headset lenses tend to be thick and are always positioned a few inches away from a display for proper focus. However, this headset is the testbed for two new technologies – a holograph of a lens instead of an actual lens and the use of specialised lasers instead of commonly used LEDs along with polarized reflection to reduce the effect of distance between the display in the eye.
“Holographs are basically recordings of what happens when light hits something. So just like a holograph is much flatter than the thing itself, holographic optics are much flatter than the lenses that they model, but they affect incoming light in pretty much the same way,” said Zuckerberg.
Abrash highlights the added uniqueness of this hack
“That catch involves getting the right light source. So Holocake requires specialised lasers, and that’s pretty different from the LEDs that are used in today’s VR headsets. And lasers aren’t that exotic these days, but they’re really not found in a lot of consumer products at the performance size and price that you need for consumer VR headsets.”
With immersive experiences gaining popularity, often under the metaverse banner, it is important for devices that will enable these to improve. There is still a debate about whether it is VR headsets that will determine the path to the metaverse, or will the technology be made compatible with devices including smartphones. Yet, these mixed reality headsets will certainly drive the more advanced immersive experiences. The work on the underlying technologies should help the next generation VR headsets become more comfortable, perhaps more affordable, and less cumbersome. That’ll be particularly relevant for the early adopters.