In this presentation, we will delve into the evolution of volume holographic optical elements (VHOEs), discussing their development alongside calculation models such as the VOHIL model. We will unveil a novel visualization scheme rooted in this model, aimed at elucidating Bragg diffraction within intricate volume holograms. Lastly, we will showcase the latest advancements in the application of VHOEs, particularly in the realm of lightguide-based Augmented Reality (AR) and Mixed Reality (MR) glasses.
Augmented Reality (AR) and Mixed Reality (MR) glasses stand as pivotal technological advancements in contemporary society. However, maintaining a compact and lightweight design while ensuring high-quality image viewing remains a persistent challenge. Researchers endeavor to overcome the intricate optical hurdles associated with these glasses. They suggest that waveguides incorporating two in- and out-coupling Volume Holographic Optical Elements (VHOEs) has surfaced as a promising approach, addressing these requirements and providing high see-through transmittance due to Bragg selectivity. Nonetheless, in the case of a full-color VHOE-based waveguide, the crosstalk between the RGB gratings of three primary colors within a waveguide results in the ghost images that diminish image quality. In this paper, we propose a method to eliminate ghost images and offer precise simulations aligned with experimental observations.
In this paper, we introduce an approach—multiplexing gratings plus drive signal management scheme implemented on a micro-display device within an optical engine—to precisely adjust the color uniformity of an Augmented Reality (AR) eyewear display. This display is based on Volume Holographic Optical Elements (VHOEs) and a waveguide. Our method simplifies the complexity of multiplexing, requiring only a single optical waveguide and three RGB gratings for primary colors to achieve a full-color eyewear display with an expansive horizontal field of view (FOV) of nearly 30° and less than 3% ΔELab color non-uniformity.
In this paper, we will discuss about the color performance and image quality of the Volume-Holographic-Optical-Element (VHOE)-based AR devices using two different type of volume holograms: transmission or reflection-type VHOEs. The simulation results show that color distortion occurring in these two types of VHOE-based AR devices are quite different and resulting from different characteristics of Bragg diffraction from those VHOEs. The reflective VHOE-based AR devices show better overall performance in terms of color, field of view and image quality.
Augmented reality (AR) is the trend of future life. Until now, many technologies have been developed for AR glass. With the high brightness and light characteristic, we use Micro-LED as the source and the metalenses array to form the collimated light. The image can be projected onto the retina using sequential scanning technology. However, the divergent angle of the collimated light would increase along with the increase in pixel number. In this paper, we simulate the collimation properties of metalenses. To increase the number of pixels, we propose to arrange the pixels on a retina well according to the simulation results. The corresponding results of the simulation and calculation will be shown.
In this study, we first focus on the study of the mass-productive Fresnel lens in the HCPV to calculate the amount of the leakage light. Then we will study the leakage light by the natural factor, such as clear sky, light cloud, medium cloud, and heavy cloud. Finally, we will summarize the characteristic of the light leakage in HCPV in considering the engineering and natural factors.
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