A Multi-plane Head-Up Display (MHUD) using the spectral and angular selectivity of Bragg Grating is presented. Most of today's automotive HUDs display information at a short distance, about 2 meters. However, a key challenge of augmented reality is to have a longer projection distance to superimpose graphics on the external landscape, without parallax issues, while keeping vehicle information at a shorter distance. As a result, the HUD needs to have at least two image planes. Existing methods to build such a multiplane lightfield HUD are complex and bulky. In this paper, we propose a new principle, using a dual PGU an then a single PGU, fitted with HOE working with the spectral dimension of the light.

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A Windshield Head-Up Display (WHUD) using an embedded optical thin film to improve the system efficiency is presented. Most of today's WHUDs, including the most advanced devices, use the windshield as a simple half-mirror, so that the main part of the optical flow is not reflected toward the eye-box. Even with recent work, aiming to increase the optical efficiency of the Picture Generating Unit, or the set of mirrors or light-guides, reflectance efficiency is not greater than 20%. Experiments performed on the first prototype using Transparent Holographic Optical Components show an optical efficiency of 85%. This result will open the way for a more compact green product device (with a huge reduction in power consumption). 55-3 / P. Coni SID 2018 DIGEST • 729ISSN 0097-996X/18/4702-0729-$1.00 © 2018 SID 55-3 / P. Coni