A Rendering Method of Microdisplay Image to Expand Pupil Movable Region without Artifacts for Lenslet Array Near-Eye Displays

Abstract

Near-eye displays (NEDs) with lenslet array (LA) are a technological advancement that generates a virtual image in the observer's field of view (FOV). Although this technology is useful for designing lightweight NEDs, undesirable artifacts (i.e., cross-talk) occur when the user's pupil becomes larger than the pupil practical movable region (PPMR) or moves out of the PPMR. We proposed a rendering method for microdisplay images that takes pupil size into account and included the idea of pupil margin in the ray tracing process. Ray lights emitted by one microdisplay pixel (MP) enter the pupil and pupil margin area after passing through a number of lenses. Each lens at the MP corresponds to one virtual pixel (VP) on the virtual image plane. The weight of each VP is the intersection area between the ray light column and the pupil and pupil margin divided by the sum of intersecting spaces between all the ray light columns generated by the MP and the pupil and pupil margin. The value of each MP is determined by the number of VPs and the related weight. Through retina image simulation studies, we confirmed that the proposed rendering approach substantially enlarges PPMR to accommodate large pupil diameters and wide transition distances while reducing eye relief to an optimal (sunglasses) distance.