Examining aberrations due to depth of field in holographic pupil replication waveguide systems

Automotive Augmented Reality Head-Up Displays

As the next generation of in-vehicle intelligent platforms, the augmented reality heads-up display (AR-HUD) has a huge information interaction capacity, can provide drivers with auxiliary driving information, avoid the distractions caused by the lower head during the driving process, and greatly improve driving safety. However, AR-HUD systems still face great challenges in the realization of multi-plane full-color display, and they cannot truly achieve the integration of virtual information and real road conditions. To overcome these problems, many new devices and materials have been applied to AR-HUDs, and many novel systems have been developed. This study first reviews some key metrics of HUDs, investigates the structures of various picture generation units (PGUs), and finally focuses on the development status of AR-HUDs, analyzes the advantages and disadvantages of existing technologies, and points out the future research directions for AR-HUDs.

Holographic curved waveguide combiner for HUD/AR with 1-D pupil expansion

We are presenting the optical ray tracing as well as an experimental prototype of a curved waveguide combiner with pupil expansion for augmented reality (AR) and mixed reality (MR) glasses. The curved waveguide combiner takes advantage of holographic optical elements both for injection and extraction of the image to correct the aberrations introduced during the propagation of light inside the waveguide. The holographic curved combiner presented has a cylindrical outer radius of curvature of 171.45 mm with a field of view of 13° (H) × 16° (V) at a viewing distance of 1 cm with a 5 × horizontal 1 dimension pupil expansion for an eyebox of 6.2 mm × 42.7 mm.

Asymmetric Diffraction in Plasmonic Meta-Gratings Using an IT-Shaped Nanoslit Array

Diffraction is a fundamental phenomenon that reveals the wave nature of light. When a plane wave is transmitted or reflected from a grating or other periodic structures, diffracted light waves propagate at several angles that are specified by the period of the given structure. When the optical period is shorter than the wavelength, constructive interference of diffracted light rays from the subwavelength-scale grating forms a uniform plane wave. Many studies have shown that through the appropriate design of meta-atom geometry, metasurfaces can be used to control light properties. However, most semitransparent metasurfaces are designed to perform symmetric operation with regard to diffraction, meaning that light diffraction occurs identically for front- and back-side illumination. We propose a simple single-layer plasmonic metasurface that achieves asymmetric diffraction by optimizing the transmission phase from two types of nanoslits with I- and T-shaped structures. As the proposed structure is designed to have a different effective period for each observation side, it is either diffractive or nondiffractive depending on the direction of observation. The designed structure exhibits a diffraction angle of 54°, which can be further tuned by applying different period conditions. We expect the proposed asymmetric diffraction meta-grating to have great potential for the miniaturized optical diffraction control systems in the infrared band and compact optical diffraction filters for integrated optics.