It seems that Rev. Kyle, the voice of the Road to VR podcast, has found out that the lenses used in the Oculus Rift Crescent Bay prototype could be Fresnel, specifically two-layer. You have to take the news with tweezers, but this would explain the almost total absence of screendoor effect and chromatic aberration.
The news has appeared in an interesting blog that talks at length about Oculus Connect. If you defend yourself well with English, we advise you to read it from end to end, since it also talks about Samsung Gear VR, Leap Motion, Tactical Haptics and, of course, Crescent Bay. As for the lenses, this is what they have found out:
We already know that the lenses are large and more drop-shaped than circular, and the very persuasive personality of Rev. Kyle has allowed him to find out that these are double-layer Fresnel lenses. This would explain the quality of the image, which looked sharp and focused throughout the entire field of view, and it is also possible that the two layers of lenses form an achromatic pair, which would simplify lens distortion and time warp.
Let’s explain what the achromatic pair consists of. These are two individual lenses made with crystals of different amounts of dispersion. Normally, the negative element (the concave one) is made of flint crystal, which has a relatively large dispersion. The other element, the positive (convex), is usually made of crown crystal, which has a lower dispersion. The two elements are mounted glued together, usually by some substance, and are placed in such a way that one corrects the chromatic aberration of the other.
