Author(s): Duarte, Moises A. S. ; Nunes-Pereira, E. J. ; Bret, Boris P. J. ; Forte, Paulo M. F. ; Ferreira, Flávio Pedro Gonçalves Fernandes ; Sousa, Marco A. ; González-Méijome, José Manuel
Date: 2019
Persistent ID: https://hdl.handle.net/1822/72968
Origin: RepositóriUM - Universidade do Minho
Subject(s): Automatic Optical Inspection; AOI; HUD; AR; VR; MR; Plenoptic Imaging; Light Field Camera
A single shot automatic optical inspection system for evaluating the projection distance, astigmatism, field curvature and geometric distortions of a virtual image created by a Head-Up Display (HUD) prototype is presented. The system uses plenoptic or light-field imaging. Although results are only presented for a Augmented Reality (AR)/Mixed Reality (MR) HUD application, the inspection workflow is also applicable to a plurality of other optical systems for AR, MR, and Virtual Reality (VR) applications. The evaluation of the quality of a latent image (in most cases a virtual image) is necessary in all these systems, both for product development as well as for end-of-line production quality control. Therefore the results here presented should have an appeal for a broad readership.For the HUD virtual image, the projected distance distribution functions are presented, for two selected patches in the FOV (Area 1 and 2). These are well described by Gaussians. As representative values, we obtained a mean projected distance of 0.15 +/- 0.02 (horizontal details) and 0.03 +/- 0.02 (vertical) Diopters, for Area 1, and 0.33 +/- 0.04 (horizontal) and 0.03 +/- 0.02 (vertical) Diopters, for Area 2. The estimated astigmatism is 0.12 and 0.30 Diopters, for Areas 1 and 2, respectively. When expressed in meters, the projected distances are 7 +/- 1 (horizontal) and 28 +/- 9 (vertical), for Area 1, and 3.1 +/- 0.4 (horizontal) and 30 +/- 10 (vertical), for Area 2. The estimated astigmatic difference is 21 and 23 meters, for Areas 1 and 2, respectively.
