Exploring the limits of CLOVER: a multichannel optics for VR and MR

Most virtual reality (VR) headsets nowadays use conventional, rotationally symmetric optics to create a wide field of view (FOV > 90°) virtual scene enabling the required “immersion” or “presence” feeling. These optics require a long total track length (TTL, distance between the actual panel displaying the contents and user’s pupil) to work well, and headsets become very bulky. The so-called CLOVER is an optic, compatible with VR and video-see-through mixed reality (MR) able to work around the TTL problem by using a freeform multi-channel, light folding approach. In its simplest version, it can reduce the TTL down to a half, compared to conventional solutions, for the same FOV and angular resolution. Along with a review of the original 4-channel CLOVER, this work shows recent results of upscale versions of the optic that utilize myopia and color correction, pupil tracking and staggered surfaces to, respectively, avoid the need of prescription lenses, improve the image quality for all colors, rise the resolution (by a 20%) and reduce the size (20% TTL reduction) of the precursor.