Search Results (7)

Meta-optics, enabled by metasurfaces consisting of two-dimensional arrays of meta-atoms, offers ultrathin and multi-functional control over the vectorial wavefront of light at subwavelength scales. The unprecedented optical element technology is a promising candidate to overcome key limitations in augmented reality (AR) and virtual reality (VR) near-eye displays particularly in achieving compact, eyeglass-type form factors with a wide field-of-view, a large eyebox, high resolution, high brightness, and reduced optical aberrations, at the same time. This review highlights key performance bottlenecks of AR/VR displays in the perspective of optical design, with an emphasis on their practical significance for advancing current technologies. We then examine how meta-optical elements are applied to VR and AR systems by introducing and analyzing the major milestone studies. In case of AR systems, particularly, two different categories, free-space and waveguide-based architectures, are introduced. For each category, we summarize studies using metasurfaces as lenses, combiners, or waveguide couplers. While meta-optics enables unprecedented miniaturization and functionality, it also faces several remaining challenges. The authors suggest potential technological directions to address such issues. By surveying recent progress and design strategies, this review provides a comprehensive perspective on the role of meta-optics in advancing the optical engineering of next-generation AR/VR near-eye displays. Full article

The immersive experience of holographic displays is fundamentally limited by their space–bandwidth product (SBP), which imposes an inherent trade-off between the field of view (FOV) and eyebox size. This paper proposes a method to extend the SBP by employing cascaded modulation with a dynamic spatial light modulator (SLM) and a passive high-resolution binary random phase mask (BRPM). We find that the key to unlocking this extension of SBP lies in a sophisticated algorithmic optimization, grounded in a physically accurate model of the system. We identify and correct the Nyquist undersampling problem caused by high-frequency scattering in standard diffraction models. Based on this physically accurate model, we employ a gradient descent optimization framework to achieve efficient, end-to-end solving for complex light fields. Simulation and experimental results demonstrate that our method achieves an approximately 16-fold SBP extension (4-fold FOV) while delivering significantly superior reconstructed image quality compared to the traditional Gerchberg–Saxton (GS) algorithm. Furthermore, this study quantitatively reveals the system’s extreme sensitivity to sub-pixel level alignment accuracy, providing critical guidance for the engineering and implementation of our proposed method. Full article

Augmented reality (AR) technology has been widely applied across a variety of fields, with head-up displays (HUDs) being one of its prominent uses, offering immersive three-dimensional (3D) experiences and interaction with digital content and the real world. AR-HUDs face challenges such as limited field of view (FOV), small eye-box, bulky form factor, and absence of accommodation cue, often compromising trade-offs between these factors. Recently, optical waveguide based on pupil replication process has attracted increasing attention as an optical element for its compact form factor and exit-pupil expansion. Despite these advantages, current waveguide displays struggle to integrate visual information with real scenes because they do not produce accommodation-capable virtual content. In this paper, we introduce a lensless accommodation-capable holographic system based on a waveguide. Our system aims to expand the eye-box at the optimal viewing distance that provides the maximum FOV. We devised a formalized CGH algorithm based on bold assumption and two constraints and successfully performed numerical observation simulation. In optical experiments, accommodation-capable images with a maximum horizontal FOV of 7.0 degrees were successfully observed within an expanded eye-box of 9.18 mm at an optimal observation distance of 112 mm. Full article

Augmented reality heads-up displays (AR-HUDs) have a much richer display than traditional heads-up displays. An ideal AR-HUD requires two or more focal planes to display basic and interactive driving information to the car driver separately. We present an off-axis reflective optical structure for dual-focal-plane displays using a single projection-type picture generation unit (PGU) and two freeform mirrors. The dual-focal-plane AR-HUD system designed in this paper can simultaneously generate high-quality far-field image (13° × 4°, 10 m) and near-field images (13° × 1.4°, 3.5 m) in a 130 mm × 60 mm eyebox. A fully automated analysis program is written to analyze the modulation transfer function (MTF) and distortion values of the optical system over the entire eyebox range. The analysis results show that the maximum distortion values of the far-field image and near-field image in the eyebox range are 3.15% and 3.58%, respectively. The MTF was greater than 0.3 at 7.2 lp/mm for both near-field images and far-field images. We also designed a projection lens for the projection-type PGU used in this system. The projection lens uses three plane mirrors to fold the image plane of the projection system into different positions to serve as the image source for the AR-HUD. This research provides a new solution for realizing the dual-focal-plane AR-HUD, which not only satisfies the need for simultaneous display of near-field basic information and far-field interactive information, but also has a larger display screen. Full article

The use of augmented reality head-up displays (AR-HUD) in automobile safety driving has drawn more and more interest in recent years. An AR-HUD display system should be developed to fit the vehicle and the complicated traffic environment in order to increase the driver’s driving concentration and improve the man–vehicle synchronization. In this article, we suggest an AR-HUD display system with dual-layer virtual-image displays for the near field and far field, as well as further research and design of the adjustment system for multi-depth displays of far-field images. It also examines the EYEBOX horizontal adjustment margin of the dual light path. The analysis results show that the scale of EYEBOX is 120 × 60 mm², the modulation transfer function (MTF) of near-field light path > 0.2 @ 6.7 lp/mm, and the MTF of far-field optical path > 0.4 @ 6.7 lp/mm. The distortion of the near-field optical path is less than 0.86%, and that of the far-field optical path is less than 2.2%. By modifying the folding mirror, the far-field optical path creates an 8 m to 24 m multi-depth virtual picture display. Image quality can be maintained when the near-field and far-field optical paths are moved horizontally by 25 mm and 100 mm, respectively. This study offers guidelines for the multi-depth display, EYEBOX horizontal adjustment, and optical layout of augmented reality head-up displays. Full article

The Maxwellian view offers a promising approach to overcome the vergence-accommodation conflict in near-eye displays, however, its pinhole-like imaging naturally limits the eyebox size. Here, a liquid crystal polymer-based Dammann grating with evenly distributed energy among different diffraction orders is developed to enlarge the eyebox of Maxwellian view displays via pupil replication. In the experiment, a 3-by-3 Dammann grating is designed and fabricated, which exhibits good efficiency and high brightness uniformity. We further construct a proof-of-concept Maxwellian view display breadboard by inserting the Dammann grating into the optical system. The prototype successfully demonstrates the enlarged eyebox and full-color operation. Our work provides a promising route of eyebox expansion in Maxwellian view displays while maintaining full-color operation, simple system configuration, compactness, and lightweight. Full article

We demonstrate a light efficient virtual reality (VR) near-eye display (NED) design based on a directional display panel and a diffractive deflection film (DDF). The DDF was essentially a high-efficiency Pancharatnam-Berry phase optical element made of liquid crystal polymer. The essence of this design is directing most of the display light into the eyebox. The proposed method is applicable for both catadioptric and dioptric VR lenses. A proof-of-concept experiment was conducted with off-the-shelf optical parts, where the light efficiency was enhanced by more than 2 times. Full article