At Oculus Connect 6 today, Facebook showed off two successors to the ‘Half Dome’ varifocal headset it first showed at F8 2018.
Varifocal means that the headset dynamically adjusts to the focus distance to be the same as the distance to the virtual object you’re looking at, which makes VR feel more real and reduces eyestrain.
While Half Dome 1 was of course impressive, the space and weight of the varifocal system did not line up with Facebook’s goal for next generation VR to be light and compact (so that it can be worn all day). Additionally, Facebook did not comment on the reliability of the mechanical system.
Half Dome 2
Half Dome 2 uses improved optics and actuators to deliver the varifocal experience in a smaller form factor. It’s 200 grams lighter than the original and substantially more compact.
Facebook also claims Half Dome 2 is more reliable than the original, thanks to a new varfiocal mechanism based on voice coil actuators and flexure hinge arrays, which reduce friction.
However, Half Dome 2 has a narrower field of view than the original. Facebook’s Michael Abrash stated that the field of view was still 20% wider than Quest, which would suggest somewhere around 115 degrees.
Half Dome 3
‘Half Dome 3’ is a more radical improvement. While the first two Half Domes use moving displays, Half Dome 3 uses a liquid crystal lens “made from a thin, alternating stack of two flat optical elements: polarization-dependent lenses (PDLs) and switchable half-wave plates”. No different field of view was given, meaning it’s likely similar to Half Dome 2’s.
This means that Half Dome 3 has no moving parts, meaning it’s not subject to the reliability concerns of the other prototypes. This makes Half Dome 3 a much more realistic prospect at one day being a mass producable headset. However, Facebook was clear that this won’t be happening “any time soon”.
It also allows it to be significantly smaller than even Half Dome 2. This is potentially the most compact full featured VR headset we’ve seen shown yet. If Facebook’s next generation headsets can one day adopt this varifocal technology and this form factor, it will enable VR to be both visually and ergonomically comfortable for hours on end.