Search Results (60)

Visual information shapes spatial perception and body representation in human augmentation. However, the perceptual consequences of viewpoint-height changes produced by sensor–display geometry are not well understood. To address this gap, we developed an interface that maps a waist-mounted stereo fisheye camera to an eye-level viewpoint on a head-mounted display in real time. Geometric and timing calibration kept latency low enough to preserve a sense of agency and enable stable untethered walking. In a within-subject study comparing head- and waist-level viewpoints, participants approached adjustable gaps, rated passability confidence (1–7), and attempted passage when confident. We also recorded walking speed and assessed post-task body representation using a questionnaire. High gaps were judged passable and low gaps were not, irrespective of viewpoint. At the middle gap, confidence decreased with a head-level viewpoint and increased with a waist-level viewpoint, and walking speed decreased when a waist-level viewpoint was combined with a chest-height gap, consistent with added caution near the decision boundary. Body image reports most often indicated a lowered head position relative to the torso, consistent with visually driven rescaling rather than morphological change. These findings show that a waist-mounted interface for mobile viewpoint-height transformation can reliably shift spatial perception. Full article

Augmented reality (AR) near-eye displays (NEDs) couple microdisplay image light to the human eye via integrated optical modules, enabling seamless virtual–real fusion. As core components that synergistically transmit and diffract light, diffractive waveguides are promising for next-generation AR NEDs but face two bottlenecks: compromised full-color performance in single-layer structures caused by grating dispersion and lack of scalable fabrication technologies. To address these, we first propose a mass-production-compatible workflow based on deep ultraviolet (DUV) lithography for large-area nanostructured optics. This workflow enables high-precision wafer-level production with 200 mm wafers and nine dies per wafer, overcomes scalability issues, and is fully compatible with straight-configuration nanostructures to ensure manufacturing feasibility. Leveraging this workflow, we develop a single-layer diffractive waveguide system for AR NEDs, which comprises a thin glass substrate, a broadband high-efficiency multi-layer dielectric in-coupler, and a 2D out-coupler that concurrently expands and out-couples light. Rigorous coupled wave analysis (RCWA) optimized coupler diffraction, while ray tracing refined guided light intensity and significantly improved exit pupil uniformity. This work establishes a foundation for full-color, high-efficiency AR waveguides and provides a scalable paradigm for large-area nanostructured optical systems such as telescopes and lithography equipment. Full article

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

Waveguide-integrated metasurfaces offer a promising platform for ultracompact on-chip optical systems, enabling applications such as fluorescence sensing, holography, and near-eye displays. In particular, integrated achromatic metalenses that couple guided modes to free-space radiation are highly desirable for single-molecule fluorescence sensing, where high numerical aperture (NA), efficient light focusing, and consistent focal volume overlap across excitation and emission wavelengths are critical. However, designing integrated high-NA metalenses with multi-wavelength operation remains fundamentally challenging due to the wavelength-dependent propagation of guided modes. Here, we present an inverse design framework that simultaneously optimizes the geometries and positions of silicon nitride nanofins atop a slab waveguide to achieve diffraction-limited focusing at three wavelengths with unity NA. The resulting metalens outperforms conventional segmented designs in focusing efficiency and sidelobe suppression, particularly at wavelengths corresponding to the excitation and emission bands of the model fluorophore Alexa Fluor 647. Numerical analysis shows that the design yields a high molecule detection efficiency suitable for epi-fluorescence single-molecule sensing. This work highlights the potential of inverse-designed metalenses as a versatile on-chip platform for advanced applications in fluorescence spectroscopy, augmented reality, or optical trapping. Full article

We present a deep learning-based approach to optimize the central angle between adjacent camera viewpoints for the efficient generation of natural 360-degree holographic 3D content. High-quality 360-degree digital holograms require the acquisition of densely sampled RGB–depth map pairs, a process that traditionally requires significant computational costs. Our method introduces a novel pipeline that systematically evaluates the impact of varying central angles—defined as the angular separation between equidistant viewpoints in an object-centered coordinate system—on both depth map estimation and holographic 3D image reconstruction. By systematically applying this pipeline, we determine the optimal central angle that achieves an effective balance between image quality and computational efficiency. Experimental investigations demonstrate that our approach significantly reduces computational demands while maintaining superior fidelity of the reconstructed 3D holographic images. The relationship between central angle selection and the resulting quality of 360-degree digital holographic 3D content is thoroughly analyzed, providing practical guidelines for the creation of immersive holographic video experiences. This work establishes a quantitative standard for the geometric configuration of viewpoint sampling in object-centered environments and advances the practical realization of real-time, high-quality holographic 3D content. Full article

Integrated light-emitting diodes (LEDs) with waveguides play an important role in applications such as augmented reality (AR) displays, particularly regarding coupling efficiency optimization. Quantum dot light-emitting diodes (QLEDs), an emerging high-performance optoelectronic device, demonstrate substantial potential for next-generation display technologies. This study investigates the influence of microcavity modulation on the output of QLEDs coupled with a silicon nitride (SiNx) waveguide by simulating a white light QLED (W-QLED) with a broad spectrum and mixed RGB QDs (RGB-QLED) with a comparatively narrower spectrum. The microcavity converts both W-QLED and RGB-QLED emissions from broadband white-light emissions into narrowband single-wavelength outputs. Specifically, both of them have demonstrated wavelength tuning and full-width at half-maximum (FWHM) narrowing across the visible spectrum from 400 nm to 750 nm due to the microcavity modulation. The resulting RGB-QLED achieves a FWHM of 11.24 nm and reaches 110.76% of the National Television System Committee 1953 (NTSC 1953) standard color gamut, which is a 20.95% improvement over W-QLED. Meanwhile, due to the Purcell effect of the microcavity, the output efficiency of the QLED coupled with a SiNx waveguide is also significantly improved by optimizing the thickness of the Ag anode and introducing a tilted reflective mirror into the SiNx waveguide. Moreover, the optimal output efficiency of RGB-QLED with the tilted Ag mirror is 10.13%, representing a tenfold increase compared to the sample without the tilted Ag mirror. This design demonstrates an efficient and compact approach for the near-eye full-color display technology. Full article

Background: This study innovatively combines Artificial Intelligence (AI) algorithms with smartphone technology, automatically detecting the Near Point of Convergence (NPC) and diagnosing Convergence Insufficiency (CI) without the need for extra diagnostic tools and, notably, without having to rely on the subject’s vocal response, marking an unprecedented approach in the field to the best of our knowledge. Methods: This was a prospective study that enrolled 86 participants. The real-time tracking of eye structures and movements was conducted using AI technologies integrated with a mobile application (MobileS). Participants brought the smartphone closer, focusing on a target displayed on the screen. The system calculated pupillary distance (PD) and phone-to-face distance, incorporating a unique feature called the exodeviation episode’s counter (ExoCounter) to determine the NPC. Additionally, participants underwent testing using the RAF Ruler test (RulerT), considering the ground truth. Results: MobileS demonstrated significant correlation with the RulerT, as evidenced by a Pearson correlation coefficient of 0.74 (p < 0.001) and an Intraclass Correlation Coefficient (ICC) of 0.73 (p < 0.001), highlighting its reliability and consistency with conventional ophthalmic testing. Additionally, the system exhibited notable sensitivity and specificity in diagnosing CI. Notably, user feedback indicated a preference for the MobileS, with 71% of participants favouring it for its ease of use and comfort. Conclusions: MobileS is a precise, user-friendly tool for independent NPC measurement, applicable in tele-ophthalmology and home-based care. Its versatility extends beyond CI diagnosis, marking a significant advancement in ophthalmic diagnostics for accessible and efficient eye care. Full article

For a near-eye display, a resolution of over 10,000 pixels per inch (PPI) for the display device is needed to eliminate the “screen door effect” and have better display quality. Electrohydrodynamic (EHD) printing techniques, which have the advantages of a high resolution, wide material applicability and flexibility in patterning, have been widely used in the printing of high-resolution structures. However, due to factors such as the extremely small size of the droplets, the electric charge, the electric field, and the unavoidable positioning error, various deposition defects can occur. For droplets at a nanoscale, the dynamic deposition process is hard to observe. The continuum hypothesis fails and the fluid cannot be described by the traditional Navier–Stokes equation. In this work, the behaviors of charged nanodroplet deposition into a microcavity in an electric field are studied. The many-body dissipative particle dynamics (MDPD) method is used to examine the deformation of the nanodroplet during the impact process at a mesoscale. The dynamic process of charged droplet deposition into a microcavity under an electric field is revealed. Strategies for failure-free printing are proposed by analyzing the influences of the impact speeds, positioning errors, charge levels and electric intensities on the out-of-pixel spread length. The relationship between the internal charge moves and the deformation of the charged droplet in the deposition process is first discussed. The spreading theory of charged droplet deposition into a microcavity with a positioning error is established by analyzing the Coulombic capillary number. Moreover, the printing parameter space that results in successful printing is acquired. Full article

According to the World Health Organization, the global population is aging, with cognitive and memory functions declining from the age of 40–50. Individuals aged 65 and older are particularly prone to dementia. Therefore, we developed an interactive system for visual cognitive training to prevent dementia and delay the onset of memory loss. The system comprises three “three-dimensional objects” with printed 2D barcodes and near-field communication (NFC) tags and operating software processing text, images, and multimedia content. Electroencephalography (EEG) data from a brainwave sensor were used to interpret brain signals. The system operates through interactive games combined with real-time feedback from EEG data to reduce the likelihood of dementia. The system provides feedback based on textual, visual, and multimedia information and offers a new form of entertainment. Thirty participants were invited to participate in a pre-test questionnaire survey. Different tasks were assigned to randomly selected participants with three-dimensional objects. Sensing technologies such as quick-response (QR) codes and near-field communication (NFC) were used to display information on smartphones. Visual content included text-image narratives and media playback. EEG was used for visual recognition and perception responses. The system was evaluated using the system usability scale (SUS). Finally, the data obtained from participants using the system were analyzed. The system improved hand-eye coordination and brain memory using interactive games. After receiving visual information, brain function was stimulated through brain stimulation and focused reading, which prevents dementia. This system could be introduced into the healthcare industry to accumulate long-term cognitive function data for the brain and personal health data to prevent the occurrence of dementia. Full article

Miniaturized pixel sizes in near-eye digital displays lead to pixel emission patterns with large divergence angles, necessitating efficient beam collimation solutions to improve the light coupling efficiency. Traditional beam collimation optics, such as lenses and cavities, are wavelength-sensitive and cannot simultaneously collimate red (R), green (G), and blue (B) light. In this work, we employed inverse design optimization and finite-difference time-domain (FDTD) simulation techniques to design a collimator comprised of nano-sized photonic structures. To alleviate the challenges of the spatial incoherence nature of micro-LED emission light, we developed a strategy called dual-task optimization. Specifically, the method models light collimation as a dual task of color routing. By optimizing a color router, which routes incident light within a small angular range to different locations based on its spectrum, we simultaneously obtained a beam collimator, which can restrict the output of the light emitted from the routing destination with a small divergence angle. We further evaluated the collimation performance for spatially incoherent RGB micro-LED light in an FDTD using a multiple-dipole simulation method, and the simulation results demonstrate that our designed collimator can increase the light coupling efficiency from approximately 30% to 60% within a divergence angle of ±20° for all R/G/B light under the spatially incoherent emission. Full article

The pancake structure is the mainstream optical solution for virtual reality (VR) displays due to its compact, folded optical path. However, only a small portion of the light can pass through the pancake optical engine because the incident light has to be polarized and directed to the half mirror (HM) twice. In order to improve the optical efficiency, a new pancake optical engine is proposed for VR display, which employs a diffractive deflection film (DDF) with different focal lengths in three regions and two cholesteric liquid crystal (CLC) lenses that respond to circularly polarized light. The CLC lenses are modeled, and their polarization response characteristics are verified. The pancake system is simulated and optimized in terms of image quality and evaluated for optical efficiency, achieving 2.86 times the optical efficiency of the conventional pancake system, and the root mean square (RMS) radius of the system is controlled within 19 μm, and the modulation transfer function (MTF) at the cut-off frequency is greater than 0.2. The results indicate that this structure has great potential in the VR display field. Full article

At present, most near-eye display devices adopt flat substrates, which have problems such as limited field of view (FOV) and bulky shape, while the curved structure is expected to expand the FOV with appropriate volume. In this paper, we propose a curved holographic augmented reality (AR) near-eye display system based on holographic optical element (HOE) with the ability to expand the FOV. The system includes a display source and a HOE with curved substrate. We analyze the system by exploiting the diffraction theory between plane and curved surface, and a layered and weighted FOV optimization method using particle swarm optimization algorithm is proposed to realize the optimization of the phase of freeform HOE. Numerical and experimental results show that the proposed curved holographic near-eye display system can realize cylindrical AR display and expand the FOV of the system. It is expected to be applied to the holographic AR near-eye display in the future. Full article

The smaller-incision new-generation implantable miniature telescope (SING IMT) represents an advancement over the previous model, WA-IMT, serving as a unilateral prosthetic device for patients with late-stage age-related macular degeneration (AMD). Purpose: This study aims to report changes in multifocal electroretinography (mfERG) 6 months post–SING IMT implantation. Methods: In this case series, we prospectively evaluated a cohort of phakic patients with late-stage AMD who underwent SING IMT implantation at the Ophthalmology Unit, University of Bari Aldo Moro, Italy. We assessed best-corrected distance visual acuity (BCDVA) and best-corrected near visual acuity (BCNVA) preoperatively and at 6 months postoperatively. Additionally, mfERGs were conducted using Retimax (CSO, Florence, Italy). Results: All four treated patients showed an increase in both BCDVA and BCNVA at the 6-month follow-up. Additionally, all eyes demonstrated increased P1 density at this time point, with the greatest augmentation observed at the central fixation point, gradually diminishing across the five concentric rings. While all patients displayed a general increase in P1 amplitude, the third patient exhibited a slight decrease in the foveal region. Conclusions: In this case series with four cases, the new generation implantable miniature telescope, SING IMT, demonstrates promising results in enhancing mfERG parameters in patients with late-stage AMD. Six months post-surgery, we observed an augmentation in both P1 density and amplitude, predominantly at the fixation point and gradually tapering in the surrounding concentric rings. Full article

Microdisplays are widely used in near-to-eye (NTE) applications that operate with batteries, and reducing the power consumption of microdisplays is key to increasing their battery life. This paper proposes a digital data driver with a data energy recycling feature to reduce its dynamic power consumption. According to the measurement results obtained from a proof-of-concept array fabricated using TSMC 65 nm technology, the power consumption of the display data driver demonstrates an average reduction of 16% when tested with 10 random black-and-white images or a 14.4% decrease when evaluated using four real-life test images. Full article

Augmented reality overlays computer-generated virtual information onto real-world scenes, enhancing user interaction and perception. However, traditional augmented reality optical systems are usually large, bulky, and have limited optical performance. In this paper, we propose a novel compact monochrome reflective dielectric metalens visor with see-through properties, engineered using a periodic structure of spin-dependent supercells. The supercell, which is composed of staggered twin nanofins, provides spin-dependent destructive or constructive interference with different circularly polarized incidences. The design combines the principles of interference with the Pancharatnam–Berry phase to enhance reflection at a working wavelength of 650 nm while maintaining good transmission. Right circularly polarized light incident from the substrate side causes destructive interference, enabling the supercell to work in reflection mode, while left circularly polarized light causes constructive interference, enabling the supercell to work in transmission mode. Furthermore, the supercell-constructed metalens can achieve near-diffraction-limited reflective focusing and a broad diagonal field of view of approximately 96°. In addition, compared to transmissive metalens visors, the reflective design eliminates the need for a beam splitter, significantly reducing the size and weight of the system. Our work could facilitate the development of compact and lightweight imaging systems and provide valuable insights for augmented reality near-eye display applications. Full article