Even though virtual reality has advanced variously in recent years, size and wearability is the major factor still holding the field back. Even of most highly-rated VR headsets, most are grunty, with wide headstraps securing a hefty front display that extends inches from the face. You’re left resembling something more like you’d be prepped to take off on a motorbike ride or launch down the ski slopes.

Facebook Reality Labs are creating a thinner prototype VR headset using holographic film. The headset looks like lightweight sunglasses, it has a total thickness of less than 9mm. The same resolution and field of view is maintained.

What does it look like?

Even though it’s thin, the prototype supposedly provides a 90-degree horizontal view field.

Facebook’s prototype uses lasers instead of LCDs. Instead of requiring pixels, they enable images at the center of the display to be clearly defined almost to one arcminute in size – close to the limits of 20/20 human vision.

The holographic films that focus the image onto the eye eliminate the need for large refractice lensing systems in most commercial headsets.

There’s plenty of work be done for thinner VR prototypes to become a feasible commercial option. This Facebook Reality Labs prototype only displays content in shades of green, viewable in this Facebook Research blog post. Also, its use of lasers instead of LCDs make it hard to get a traditional pixel-based resolution measurement. The display’s resolution also has “significant ghosting”, varying as you move away from the 60-degree center field of view.

To prevent additional bulk, the Facebook Research team had to omit everything except a single monocular display that is geared away from the headset’s frame. The researchers comment, “A truly portable and practical display would integrate a pair of display modules, a computing platform, batteries, positional trackers, and all external components into a sunglasses-like frame.”

How does it work?

In the recently published SCM Siggraph paper, Holographic Optics for Thin and Lightweight Virtual Reality, Facebook reserachers Andrew Maimone and Junren Wang outline the optics of their lightweight prototype. The polarised films use “pancake optics”, a light-folding technique that reflects the displayed image in a small space over multiple times.

Instead of needing a large physical space for the light to travel through, the apparent focal length of the image is extended.

Virtual for the future?

These practical visors are an exciting revolution in the future of VR displays – but we’re a far-way off these as commercial-level products. For one thing, getting full-colour images with a laser-type design will require detailed engineering and overlaying of red and blue lasers.

Research sourced from Facebook Research Lab.