Where prior Oculus Rift kits shipped with interchangeable circular lenses (left), the CV1 uses a single set of non-removable, asymmetric lenses (right).

A closeup of the CV1 lens reveals these concentric rings, a telltale sign of Fresnel lenses. These cleverly manufactured lenses do the same job as the thick, bulging, curved plastic lenses seen in prior Rifts—using thin arrays of concentric prisms that weigh far less.

The Fresnel lens yields the same large viewing angle and short focal length, but with a fraction of the material—which is exactly what VR needs. It all has to go into a brick-sized device you can strap to your face for hours, without putting a strain on your poor neck muscles.

Bonus round: by varying the size and shape of the concentric prisms, Oculus was able to fine-tune the lens for this specific application, minimizing spherical aberrations (or distortions) that may result from a traditional curved lens. This probably explains the asymmetric shape.