Light field displays with computational vision correction for astigmatism and high-order aberrations with real-time implementation

Abstract

Vision-correcting near-eye displays are necessary concerning the large population with refractive errors. However, varifocal optics cannot effectively address astigmatism (AST) and high-order aberration (HOAs); freeform optics has little prescription flexibility. Thus, a computational solution is desired to correct AST and HOA with high prescription flexibility and no increase in volume and hardware complexity. In addition, the computational complexity should support real-time rendering. We propose that the light field display can achieve such computational vision correction by manipulating sampling rays so that rays forming a voxel are re-focused on the retina. The ray manipulation merely requires updating the elemental image array (EIA), being a fully computational solution. The correction is first calculated based on an eye’s wavefront map and then refined by a simulator performing iterative optimization with a schematic eye model. Using examples of HOA and AST, we demonstrate that corrected EIAs make sampling rays distributed within ±1 arcmin on the retina. Correspondingly, the synthesized image is recovered to nearly as clear as normal vision. We also propose a new voxel-based EIA generation method considering the computational complexity. All voxel positions and the mapping between voxels and their homogeneous pixels are acquired in advance and stored as a lookup table, bringing about an ultra-fast rendering speed of 10 ms per frame with no cost in computing hardware and rendering accuracy. Finally, experimental verification is carried out by introducing the HOA and AST with customized lenses in front of a camera. As a result, significantly recovered images are reported.

Real-time computer-generated integral imaging light field displays: revisiting the point retracing rendering method from a signal processing point of view

“…The flexibility of raytracing is not a bonus of our method but an essential benefit when the pinhole model is insufficient. For example, we recently proposed a computational vision-correcting InIm-LFD [30], where all rays from voxels to pixels must be corrected according to an eyeball's wavefront map. The viewpoint-based approach is even unavailable in that scenario, while the proposed method is unaffected.…”

A varifocal augmented reality head‐up display using Alvarez freeform lenses

“…4 Varifocal displays can be implemented computationally or physically. The former approach includes light field display and digital holography [15][16][17][18][19][20][21] ; however, utilizing them for commercially competitive HUDs is challenging, though they have been widely studied for head-mounted displays. Light field displays suffer from an intrinsic trade-off between spatial and depth resolution.…”