Volumetric Display Research Articles

Enhanced upconversion luminescence of Er3+/Y3+ co-doped tellurite glasses for volumetric three-dimensional display

Large-sized Er3+/Y3+ co-doped tellurite glasses with high image quality were prepared by a conventional melt-quenching method for volumetric three-dimensional display. The effects of the concentration of Er3+ and Y3+ on the two-frequency upconversion luminescence properties and volumetric three-dimensional display were investigated. Under dual-wavelength excitation at 850 nm and 1550 nm, the two-frequency two-step upconversion luminescence intensity at 546 nm in the Er3+/Y3+ co-doped tellurite glass was significantly enhanced by about 44% compared with that in the Er3+ doped tellurite glass. However, the upconversion luminescence mechanism and its dynamic process were further obtained. A range of the high-resolution and high-contrast volumetric three-dimensional images can be achieved in the Er3+/Y3+ co-doped tellurite glass with optimal doping concentration, utilizing a coordinated control system of galvanometer scanner and digital micro-mirror devices. The results indicate that Er3+/Y3+ co-doped tellurite glass has promising potential for widely volumetric 3D displays.

Multicolor Tunable Upconversion Luminescence via Near‐Infrared Manipulation of Population Pathways of Er3+ Ions Excited‐State Levels for Volumetric Color Displays

AbstractPrecise control over multicolor luminescence of upconversion nanoparticles (UCNPs) is of significant importance for their applications in widespread fields of research. However, realizing the tunable emissions in single UCNPs with a single lanthanide element remains a great challenge. Herein, without multiple lanthanide elements, a new strategy for the regulation of the excited‐state level population pathways of the same lanthanide activator Er3+ ion to obtain multicolor‐tunable upconversion luminescence is proposed through utilizing 980 nm coupled 1973 nm synergistic excitation. Unlike typical single wavelength excitation, the synergistic excitation may affect population pathways of the excited‐state level of Er3+ ion by adjusting excitation wavelength and power density, resulting in a dynamically adjustable change in luminescence color output. Notably, multicolor luminescence involving green, chartreuse, yellow, orange, and red can be tuned dynamically in the NaYF4:Er3+ single UCNPs by using the tunable 980/1973 nm synergistic excitation. This dynamic luminescence color variation from these UCNPs has demonstrated promising potential applications in volumetric color display. The results provide a new approach to achieve multicolor‐tunable upconversion luminescence at single nanoparticles level and open up the possibility of developing true three‐dimensional volumetric color display technologies with resolution at the nanometer range.

Tricolor Upconversion Phosphors of LiYO2:RE3+/Yb3+ (RE = Tm, Ho, Eu) for Metamerism Anti‐Counterfeiting and 3D Volumetric Display

AbstractThe development of blue/green/red tricolor upconversion (UC) phosphors under invisible light irradiation has attracted significant interest in emerging applications such as anti‐counterfeiting, three‐dimensional (3D) optical data storage, and solid‐state 3D displays. In this study, a series of LiYO2:RE3+,Yb3+ (RE = Tm, Ho, Eu) phosphors are successfully prepared via first precipitation process followed by calcination, and completely optimized for efficient tricolor UC luminescence with 980 nm laser excitation. Mechanisms involving two‐ or three‐photon absorption processes and low‐phonon‐energy‐suppressed multi‐phonon relaxation have been proposed for Ho3+(Eu3+)/Yb3+ and Tm3+/Yb3+ codoping, respectively. In addition, the RE3+ (Yb3+) concentration‐induced phase transition of the LiYO2 host is discussed for interesting possibilities in spectral regulation. Based on the broad color gamut achieved by the tricolor UC phosphor mixture, homochromatic and polychromatic metamerisms are experimentally fabricated via screen printing for high‐level anti‐counterfeiting and information security. Moreover, for a proof‐of‐concept demonstration, prototypes of 3D optical data storage and volumetric displays are constructed by embedding tricolor UC mixtures and their 3D printed patterns in polydimethylsiloxane. It is believed that the continuous exploration of tricolor UC under invisible light excitation for metamerism anti‐counterfeiting and 3D displays can promote the development of high‐level information security and advanced volumetric display technologies.

Expanding the Viewable Area of Directional Volumetric Displays

Expanding the Viewable Area of Directional Volumetric Displays

Enhancing Image Quality in Directional Volumetric Displays with Red-Net

Enhancing Image Quality in Directional Volumetric Displays with Red-Net

Height Adjustment of Directional Volumetric Displays Using Deep Learning

Height Adjustment of Directional Volumetric Displays Using Deep Learning

Deep learning-empowered moving cascaded acoustic holography for high-fidelity and high-capacity acoustic holographic reconstruction

Acoustic holograms offer a promising platform for reconstructing complex acoustic fields with high resolution in three dimensions. However, traditional design algorithms based on single acoustic holograms have limitations in terms of their information capacity. To address this challenge, our study proposes a novel strategy called deep learning-empowered moving cascaded acoustic holography. This strategy enables high-capacity target patterns to be encoded onto two moving cascaded acoustic phase plates at a set of movable distances along the forward diffractive path of the incident acoustic wave. To achieve the high-fidelity and high-capacity acoustic holographic reconstruction, we develop a physics-enhanced moving cascaded acoustic hologram deep neural network (PhysNet_MCAH) method, which employs a physics-driven neural network to inversely design the phase offset distributions of two phase plates. Our results demonstrate that the PhysNet_MCAH method effectively generates high-fidelity and high-capacity moving cascaded acoustic holograms that are capable of rendering different complex target patterns at different design movable distances. Additionally, we show that moving cascaded acoustic holograms significantly improve the holographic storage capacity and enhance acoustic field reconstruction accuracy, surpassing the capabilities of moving single acoustic holograms. Remarkably, we further demonstrate that the proposed PhysNet_MCAH method achieves a superior performance in terms of the trade-off between reconstruction quality and holographic storage capacity when compared to existing unsupervised deep learning methods and multiplexing strategies for designing the multi-plane or cascaded holograms. Our method offers a new paradigm for high-capacity acoustic volumetric display, dynamic particle manipulation, and other applications.

Multi-plane acoustic hologram generation with a physics-enhanced neural network for micro-particle manipulation

A physics-enhanced multi-plane acoustic hologram deep neural network (PhysenNet_MPAH) approach is proposed for generating multi-plane acoustic hologram. By combining a convolutional neural network with a physical model, the PhysenNet_MPAH approach can generate high-quality acoustic holograms for holographic rendering of targeted acoustic intensity fields at multiple planes. This approach is capable of reconstructing both strong and weak-targeted multi-plane fields, with superior quality compared to traditional iterative angular spectrum approach. The reconstructed multi-plane acoustic fields are also demonstrated to be useful for three-dimensional particles manipulation, indicating potential applications in dynamic particles manipulation and volumetric display.

Afterglow Phosphor Goes Transparent.

Recently, transparent afterglow phosphors have attracted increasing interest due to the mitigated self-absorption and the ensuing improved light output, which have inspired many advanced applications, including volumetric display and three-dimensional optical encryption. To date, the most successful afterglow phosphors remain those traditional oxide, nitride, or sulfide powders which are not transparent due to a severe scattering effect. By reduction of the number of interfaces and engineering the refractive index, the scattering effect could be circumvented effectively. To this end, four material systems, including transparent afterglow single crystals, transparent phosphorescent organics, transparent afterglow glass, and luminescent nanocomposites, were reviewed in this Perspective. We started with the discussion of the nontransparency origin. Through a careful inspection of Rayleigh scattering theory, a general solution involving both refractive index and particle size was proposed to reduce the scattering effect. Many representative works on transparent afterglow phosphors were systematically reviewed, where the typical synthesis methods and the advantages and disadvantages of each system were critically presented. In the last part, bottlenecks, prospects, and future development directions based on transparent afterglow phosphors are proposed.

Brain activity underlying visual search in depth when viewing volumetric multiplanar images

The study investigated the cortical activity associated with 3D and 2D image perception on a volumetric multiplanar display by analyzing event-related potentials (ERPs) and power spectral density (PSD). In this study, we used a volumetric multiplanar display to present visual targets, and the brain signals were recorded via an EEG amplifier and analyzed using the EEGLAB toolbox on MATLAB. The study found no significant differences in amplitude between the 3D and 2D conditions across five occipital and parietal electrodes. However, there was a significant difference in latency of the P3 component on the Pz electrode. The analysis of PSD showed no significant differences between the two conditions, although there was a slightly higher alpha and beta activity observed in the 2D visualization. The study concluded that 3D image representation on a volumetric multiplanar display has no more sensory or cognitive load on the human brain than 2D representation, and that depth perception on a multiplanar display requires less brain activity.

Luminescent Materials for Volumetric Three-Dimensional Displays Based on Photoactivated Phosphorescence.

True three-dimensional (3D) displays are the best display technologies and their breakthrough is primarily due to advancements in display media. In this paper, we propose two luminescent materials for a static volumetric 3D display based on photoactivated phosphorescence. The luminescent materials include (1) dimethyl sulfoxide (DMSO)/1-methyl-2-pyrrolidinone (NMP) or tetramethylene sulfoxide (TMSO) as the solvent and photochemically-deoxygenating reagent; (2) a metal phthalocyanine complex as the sensitizer; (3) a phosphorescent platinum complex as the emitter. The metal phthalocyanine complex, PdPrPc (PdBuPc), absorbs the light beam of 635 nm and the solvent scavenges the sensitized singlet oxygen. Light beams pass through a deoxygenated zone. The phosphorescent emitter, PtNI, absorbs the 440 nm light beam and phosphoresces only in the deoxygenated zone generated by the sensitizer. Phosphorescent voxels and high-contrast 3D images are well-defined at the intersection of 635 and 440 nm light beams.

Ultralong afterglow and unity quantum yield from a transparent CsCdCl3:Mn crystal

AbstractTransparent afterglow crystals are keenly desired for three‐dimensional information storage. Herein, CsCdCl3 perovskite crystals were grown by a programmable cooling procedure in a hydrothermal reactor. The pristine crystal showed an abnormal optical behavior where the absorption increased by 2.3 folds at high temperature, leading to a fourfold boost of photoluminescence (PL) intensity. After Mn2+ doping, the PL quantum yield was improved to nearly unity. Importantly, the doped crystals exhibited an ultralong afterglow up to 12 h after ceasing UV excitation and a high transmittance up to 75% in the visible region. This work brought a new member to the library of transparent afterglow crystal, opening up many possibilities to advanced applications such as volumetric display and three‐dimensional information encryption.

Multi-frequency acoustic hologram generation with a physics-enhanced deep neural network

Here, a physics-enhanced multi-frequency acoustic hologram deep neural network (PhysNet_MFAH) method is proposed for designing multi-frequency acoustic holograms, which is built by incorporating multiple physical models that represent the physical processes of acoustic waves propagation for a set of design frequencies into a deep neural network. It is demonstrated that one needs only to feed a set of frequency-specific target patterns into the network, the proposed PhysNet_MFAH method can automatically, accurately, and rapidly generate a high-quality multi-frequency acoustic hologram for holographic rendering of different target acoustic fields in the same or distinct regions of the target plane when driven at different frequencies. Remarkably, it is also demonstrated that the proposed PhysNet_MFAH method can achieve a higher quality of the reconstructed acoustic intensity fields than the existing optimization methods IASA and DS for designing multi-frequency acoustic holograms at a relatively fast-computational speed. Furthermore, the performance dependencies of the proposed PhysNet_MFAH method on different design parameters are established, which provide insight into the performance of the reconstructed acoustic intensity fields when subject to different design conditions of the proposed PhysNet_MFAH method. We believe that the proposed PhysNet_MFAH method can facilitate many potential applications of acoustic holograms, ranging from dynamic particle manipulation to volumetric display.

Orthogonal Trichromatic Upconversion with High Color Purity in Core‐Shell Nanoparticles for a Full‐Color Display

AbstractMaterials with tunable emission colors has attracted increasing interest in both fundamental research and applications. As a key member of light‐emitting materials family, lanthanide doped upconversion nanoparticles (UCNPs) have been intensively demonstrated to emit light in any color upon near‐infrared excitation. However, realizing the trichromatic emission in UCNPs with a fixed composition remains a great challenge. Here, without excitation pulsed modulation and three different near‐infrared pumping, we report an experimental design to fine‐control emission in the full color gamut from core–shell‐structured UCNPs by manipulating the energy migration through dual‐channel pump scheme. We also demonstrate their potential application in full‐color display. These findings may benefit the future development of convenient and versatile optical methos for multicolor tuning and open up the possibility of constructing full‐color volumetric display systems with high spatiotemporal resolution.

Orthogonal Trichromatic Upconversion with High Color Purity in Core-Shell Nanoparticles for a Full-Color Display.

Materials with tunable emission colors has attracted increasing interest in both fundamental research and applications. As a key member of light-emitting materials family, lanthanide doped upconversion nanoparticles (UCNPs) have been intensively demonstrated to emit light in any color upon near-infrared excitation. However, realizing the trichromatic emission in UCNPs with a fixed composition remains a great challenge. Here, without excitation pulsed modulation and three different near-infrared pumping, we report an experimental design to fine-control emission in the full color gamut from core-shell-structured UCNPs by manipulating the energy migration through dual-channel pump scheme. We also demonstrate their potential application in full-color display. These findings may benefit the future development of convenient and versatile optical methos for multicolor tuning and open up the possibility of constructing full-color volumetric display systems with high spatiotemporal resolution.

螺旋状回転スクリーンを用いた体積型立体表示方式の可視領域の拡大

高速回転する螺旋状スクリーンに断面画像をプロジェクタから順次照射し，残像効果により立体像を表示する体積型立体表示方式は，裸眼で全方位から立体像を観察可能であるが，回転する螺旋状スクリーンにより立体像表示空間に不可視領域が生じる課題がある．本研究では螺旋スクリーンを透過型とすることで可視領域の拡大を像の視認性を損なわずに可能かについて検証した．光路計算により示された可視領域の拡大を，試作透過型スクリーンの使用時の表示実験により確認した．また，コントラストを求める式の導出とコントラストの実測より背景光の影響を確認し，背景光の抑制により透過型スクリーン使用時にもコントラストの低下を損なわずに立体像を表示可能なことを明らかにした．

Development of a Video Projection System using Multiple Projectors on a Directional Volumetric Display

Development of a Video Projection System using Multiple Projectors on a Directional Volumetric Display

The Proposal of Image Quality Improvement Method for Directional Volumetric Displays Using Deep Learning

The Proposal of Image Quality Improvement Method for Directional Volumetric Displays Using Deep Learning

Development of a Holographic Directional Volumetric Display Prototype

Development of a Holographic Directional Volumetric Display Prototype

360-degree mixed reality volumetric display using an asymmetric diffusive holographic optical element.

Volumetric display technique has a great advantage of displaying realistic three-dimensional contents with a 360-degree viewing angle. However, most volumetric displays cannot provide mixed reality because their screens inside the displays obstruct the external scene. We design a 360-degree mixed-reality volumetric display using an asymmetric diffusive holographic optical element (ADHOE). The ADHOE has wavelength selectivity, and it diffuses the light with the only specific wavelength for the virtual object, so it is possible to optically combine the virtual object and the real scene. Also, the ADHOE has different vertical and horizontal diffusing angles, and it is suitable for a horizontal-parallax-only application. In our system, the parallax images are generated by the DMD, and they are projected sequentially on the ADHOE. The ADHOE is shaped as a slanted curved surface with respect to the optical axis, and some annoying color dispersion is observed due to the mismatch between the diffraction peak points of two different wavelengths. In order to solve this problem, the carrier frequency is applied to green elemental images and the proper Fourier filter cuts off the unwanted diffraction peak points. The Fourier transform with 2f optics is built to record the ADHOE where the angular spectral bandwidth is determined by adjusting the width of the incident object light. A 360-degree see-through display with ADHOE is implemented and the feasibility of mixed reality is verified successfully.