Oculus’ Varifocal Prototype Half Dome has Two New Variants

The first day of Oculus Connect 6 (OC6) looked like it was going to be dominated by software updates and announcements as plenty of new hardware has been released in 2019. Thankfully, Facebook Reality Lab Chief Scientist Michael Abrash used his portion of the keynote to update everyone on Half Dome, the prototype headset first revealed during OC5 which featured mechanical varifocal displays. The team has been working on not one but two designs, both tackling different problems. 

Abrash unveiled Half Dome 2 and Half Dome 3 prototypes, both significantly sleeker and smaller than the original model. The 2018 version featured Fresnel lenses with a 140° field of view (FoV) with mechanically driven displays based on eye-tracking to ensure the image remains sharp. Half Dome 2 improves on this design in a number of ways, with the team looking at ergonomics and comfort.

As is noticeable from the images, the Half Dome 2 prototype is substantially smaller and lighter, with a weight reduction of 200 grams over its predecessor. This has meant the FoV is narrower than Half Dome 1 but still wider than Oculus Quest.

When it comes to Half Dome 3 the team designed an electronic version of the varifocal mechanism, replacing the mechanical parts with a new type of liquid crystal lens made of two optical elements: polarization-dependent lenses (PDLs) and switchable half-wave plates.

“PDLs are special because their focal length changes based on their polarization state. By changing the voltage applied to the switchable plates, we can toggle between the two focal lengths. This could make for a great set of digital bifocals, but it doesn’t necessarily make for comfortable VR. By stacking a series of PDLs and switchable half-wave plates on top of each other, we’re able to achieve smooth varifocal that lets you comfortably and seamlessly adjust your focus in the headset,” explains the team on Oculus Blog.

The Half Dome 3 design may still be in the prototype stage but the new design certainly offers a tidy form factor going forward. As further details on Facebook Reality Labs’ Half Dome prototypes are revealed, VRFocus will let you know.

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