Holographic Display System Research Articles

3D Multiview Holographic Display with Wide Field of View Based on Metasurface

Abstract3D display technology offers a more realistic visual experience by allowing users to perceive depth and spatial awareness, enhancing interactivity and immersion. Among various approaches, multiview display technology constructs 3D images by offering multiple smooth views along the horizontal plane. Metasurfaces, with ultra‐thin physical structures and flexible functional designs, are positioned to make significant contributions to the evolution of 3D display technologies. Here, a 3D multiview holographic display system based on metasurfaces is proposed. Using generalized Snell's law, a spatially multiplexed metasurface is designed with nine views and achieves 3D display by cascading the metasurface with a spatial light modulator (SLM). By projecting holograms onto different areas of the metasurface via the SLM, corresponding reconstructed images can be observed from specific designed directions. Thanks to the large numerical aperture (NA) of the metasurface, the system successfully achieves nine views within a 120° field of view (FOV, with a theoretical maximum of 180°), validated experimentally. This system promises potential applications in VR/AR display, surgical navigation, geographic information system (GIS), and other fields.

Speckle reduced holographic display system with a jointly optimized rotating phase mask.

Speckle noise degrades image quality in systems with coherent light sources, which must be overcome in holographic displays. In this Letter, we introduce a holographic display system with a rotating phase mask for speckle noise reduction. The rotating phase mask works in a similar way as a conventional rotating diffuser, but its pattern is jointly optimized with the spatial light modulator to maintain the contrast of the reconstructed image. The effectiveness of our system is verified through both numerical simulations and a tabletop prototype, reducing the speckle contrast by 38.8% while preserving the image quality.

Ultra-wide viewing angle holographic display system based on spherical diffraction

In the field of holographic displays, achieving a large viewing angle (LVA) has long been an essential and formidable challenge due to the limited diffraction angle of planar spatial light modulators (SLMs). Spherical holography, which allows observation from all perspectives, represents a practical approach to achieve the LVA. However, the physical limitations of commercial SLMs constrain direct implementation, making the realization of spherical holographic displays almost impractical and thus hindering technological advancement. This paper introduces an optical solution for spherical holographic display system, enabling the accurate reproduction of ultra-wide viewing angles and large objects. Our system utilizes a novel technique involving a convex parabolic mirror to convert an incident plane wave into a spherical wave. This innovative strategy permits the use of a planar SLM to create a 360°spherical holographic display. Additionally, we address the sampling issue for generating spherical holograms by constraining the point spread function (PSF), reducing the number of samples, and adapting it for visible light. Numerical simulations and optical experiments validate our success in achieving an ultra-wide viewing angle with a 360°horizontal angle and an 80°zenith angle range. Our system outperforms the state-of-the-art holographic-optical-elements approach both in computation speed and object size. We believe that our work significantly advances spherical holographic displays and offers a practical solution with vast potential applications in medicine, geology, and astronomy.

Phase space framework enables a variable-scale diffraction model for coherent imaging and display

The fast algorithms in Fourier optics have invigorated multifunctional device design and advanced imaging technologies. However, the necessity for fast computations limits the widely used conventional Fourier methods, where the image plane has a fixed size at certain diffraction distances. These limitations pose challenges in intricate scaling transformations, 3D reconstructions, and full-color displays. Currently, the lack of effective solutions makes people often resort to pre-processing that compromises fidelity. In this paper, leveraging a higher-dimensional phase space method, a universal framework is proposed for customized diffraction calculation methods. Within this framework, a variable-scale diffraction computation model is established for adjusting the size of the image plane and can be operated by fast algorithms. The model’s robust variable-scale capabilities and its aberration automatic correction capability are validated for full-color holography, and high fidelity is achieved. The tomography experiments demonstrate that this model provides a superior solution for holographic 3D reconstruction. In addition, this model is applied to achieve full-color metasurface holography with near-zero crosstalk, showcasing its versatile applicability at nanoscale. Our model presents significant prospects for applications in the optics community, such as beam shaping, computer-generated holograms (CGHs), augmented reality (AR), metasurface optical elements (MOEs), and advanced holographic head-up display (HUD) systems.

Holographic voice-interactive system with Taylor Rayleigh-Sommerfeld based point cloud gridding

In recent years, intelligent voice interaction technology and holographic display technology have garnered significant attention. We propose a holographic voice-interactive system. The holographic voice interaction system can provide users with a virtual assistant proficient in accurately handling user voice queries, facilitating smoother interactions. Additionally, users can interact with virtual objects via holographic projection, enhancing realism and engagement. In this research, we introduce the U-blocks and U-net based reverse attention residual algorithm to generate more effective and accurate point cloud datasets during the acquisition phase. Furthermore, we integrate the ChatGLM pre-trained language model as the core module for voice interaction in the holographic display system, covering aspects such as text interaction and output control. Additionally, we propose a Taylor Rayleigh-Sommerfeld point cloud gridding method aimed at improving the computational speed of hologram generation. We validate the feasibility of our proposed methods through numerical simulations and optical experiments.

Color spherical holographic display system based on conformal diffraction principle

The ideal spherical holographic display promises an expanded field of view, which allows for observation from all angles. However, challenges still exist in the spherical holographic display, primarily stemming from the planar modulator and the holographic distortion. Here, a color spherical holographic display system based on conformal diffraction principle is proposed. The core components of the system include a color laser and a spatial light modulator loaded with spherical holograms. A synchronous sequential controller is developed to achieve color dynamic holographic display. Furthermore, the conformal diffraction principle is proposed to generate distortion-free holograms. Based on the principle, the recorded object is characterized as a conformal spherical object, and a precise correspondence between the hologram and the spherical reconstructed image is established. By leveraging the proposed system, the full-color high-quality spherical holographic display with expanded viewing angles can be realized, which can flexibly adapt to different holographic display scenes. The proposed system advocates the application of spherical holographic display and has potential applications in several fields.

Point cloud holographic encryption display system involving 3D face recognition and air-writing.

In this study, we proposed a holographic identity verification encryption system that integrates face recognition, air-writing, and the multiple point cloud gridding encryption (M-PCGE) method to ensure multi-level security for objects. The experimental results show that the M-PCGE algorithm proposed in this paper achieves image encryption and decryption quickly with a high degree of restoration, and the security is verified.

An Interactive Holographic Multimedia Technology and Its Application in the Preservation and Dissemination of Intangible Cultural Heritage

Digital technology offers numerous advantages, such as preserving the authenticity, replicating reality, and facilitating dissemination. It enables the preservation of intangible cultural heritage (ICH) in its original form and allows for the creation of comprehensive graphic, audio, and visual databases. Among these technologies, holographic technology holds promise for protecting ICH and promoting its dissemination. This paper focuses on interactive holographic technology and presents the design and implementation of a dynamic holographic display system that combines digital hologram (DH) and computer-generated hologram (CGH) to showcase 3D images consisting of both virtual and real objects. Real-time loading of DH into a spatial light modulator enables the optical reproduction of real objects, while the loading of two CGHs into other spatial light modulators facilitates the optical reproduction of virtual objects. Computational holography allows for the addition of virtual information, such as coordinate text, and the fusion of the three reconstructed images in space, resulting in an augmented reality experience and enhanced 3D display of real objects. An experimental setup employing three liquid crystal on silicon (LCOS) devices confirms the validity of the proposed method. Compared to other techniques, this approach demonstrates improved image signal-to-noise ratio, reduced alignment errors, and wider coverage of light traversal for laser 3D reconstruction images. The holographic technology presented in this paper enables the fusion display of real and virtual scenes and real-time two-way interaction between the audience and virtual images. This research holds significant practical value in promoting the effective dissemination and protection of ICH.

Fluorescence-guided surgical system using holographic display: from phantom studies to canine patients.

Holographic display technology is a promising area of research that can lead to significant advancements in cancer surgery. We present the benefits of combining bioinspired multispectral imaging technology with holographic goggles for fluorescence-guided cancer surgery. Through a series of experiments with 43D-printed phantoms, small animal models of cancer, and surgeries on canine patients with head and neck cancer, we showcase the advantages of this holistic approach. The aim of our study is to demonstrate the feasibility and potential benefits of utilizing holographic display for fluorescence-guided surgery through a series of experiments involving 3D-printed phantoms and canine patients with head and neck cancer. We explore the integration of a bioinspired camera with a mixed reality headset to project fluorescent images as holograms onto a see-through display, and we demonstrate the potential benefits of this technology through benchtop and in vivo animal studies. Our complete imaging and holographic display system showcased improved delineation of fluorescent targets in phantoms compared with the 2D monitor display approach and easy integration into the veterinarian surgical workflow. Based on our findings, it is evident that our comprehensive approach, which combines a bioinspired multispectral imaging sensor with holographic goggles, holds promise in enhancing the presentation of fluorescent information to surgeons during intraoperative scenarios while minimizing disruptions.

A Full-Color Holographic System Based on Taylor Rayleigh–Sommerfeld Diffraction Point Cloud Grid Algorithm

Real objects-based full-color holographic display systems usually collect data with a depth camera and then modulate the input light source to reconstruct the color three-dimensional scene of the real object. However, at present, the main problems of the real-time high quality full-color 3D display are slow speed, low reconstruction quality, and high consumption of hardware resources caused by excessive computing. Based on the hybrid Taylor Rayleigh–Sommerfeld diffraction algorithm and previous studies on full-color holographic systems, our paper proposes Taylor Rayleigh–Sommerfeld diffraction point cloud grid algorithm (TR-PCG), which is to perform Taylor expansion on the radial value of Rayleigh–Sommerfeld diffraction in the hologram generation stage and modify the data type to effectively accelerate the calculation speed and ensure the reconstruction quality. Compared with the wave-front recording plane, traditional point cloud gridding (PCG), C-PCG, and Rayleigh–Sommerfeld PCG without Taylor expansion, the computational complexity is significantly reduced. We demonstrate the feasibility of the proposed method through experiments.

Binocular full-color holographic three-dimensional near eye display using a single SLM.

A binocular full-color holographic three-dimensional near eye display system using a single spatial light modulator (SLM) is proposed. In the display system, the frequency spectrum shifting operation and color spectrum shifting operation are adopted to realize the frequency division multiplexing (FDM) and frequency superposition multiplexing (FSM) by manipulating the frequency spectrums of each color- and view-channel sub-holograms. The FDM combined with polarization multiplexing will be used to implement binocular display using a single SLM, and the FSM working with a bandpass filter for each view-channel will be used to achieve full-color display from single frame hologram. The optical analysis and experiments with 3D color objects confirm the feasibility of the proposed system in the practical application.

Complex amplitude modulated holographic display system based on polarization grating.

We propose a holographic display system for complex amplitude modulation (CAM) using a phase-only spatial light modulator (SLM) and two polarization gratings (PG). The two sub-holograms of the complex-amplitude computed generated hologram (CGH) are loaded in different regions of SLM. Two diffractive components couple in space after longitudinal migration from the double PGs, and finally interfered through the line polarizer. The influence of the system error on the reconstructed image quality is analyzed, which provides a theoretical assessment for adding pre-compensation to CGH to compensate the system error. Moreover, on the base of the proposed system, a large depth of field and enlarged display area display is realized and the real-time display can be achieved because of the analytical complex-amplitude computed generated hologram. The optical experimental results show that the proposed system has high energy efficiency, and can provide high-quality holographic display with a large depth of field and enlarged display area.

Holographic Near-Eye Display System with Expanded Eyebox Based on Waveguide

Holographic Near-Eye Display System with Expanded Eyebox Based on Waveguide

Dual‐view holographic AR display based on Bragg mismatched reconstruction of the holographic optical element

AbstractA method for dual‐view holographic display based on Bragg mismatched reconstruction of holographic optical element (HOE) is proposed. Under the Bragg mismatched condition, the reconstructed images are guided into two separated viewing zones to realize dual‐view holographic display. Meanwhile, the viewing angle of each perspective is increased to 11.2°, which is almost 2.5 times as large as the traditional holographic display system. The design process of HOE is simple only by interference of plane reference wave and converging spherical signal wave, which has high practicability. Furthermore, the HOE can mix the virtual 3D image with real‐world scenes, which could implement augmented reality (AR) display. Experiments validate that the proposed system can achieve dual‐view holographic AR three‐dimensional (3D) display with accommodation effect.

High-Quality Holographic 3D Display System Based on Virtual Splicing of Spatial Light Modulator

High-Quality Holographic 3D Display System Based on Virtual Splicing of Spatial Light Modulator

Speckle-free compact holographic near-eye display using camera-in-the-loop optimization with phase constraint.

We present a compact holographic near-eye display system with high-quality speckle-free optical reconstructions using camera-in-the-loop (CITL) optimization with phase constraint strategy. The CITL optimization with phase constraint is used to iteratively synthesize the computer-generated holograms (CGHs) based on the in-system optical feedback. The phase constraint embedded into the whole CGH optimization process can effectively smooth the phase profile of reconstructed wave field, which helps to suppress the speckle noise caused by the phase singularities in CGH reconstruction. Numerical and optical experiments have been performed to demonstrate that the proposed method can provide speckle-free optical reconstructions with excellent image fidelity for holographic near-eye display in a compact setup.

Practical method for dynamic color holographic display.

A practical method for dynamic color holographic display by using a computer-generated hologram (CGH) with a high space-bandwidth product is proposed, and a dynamic color holographic display system is designed by a space-division method. First, three primary color CGHs of different frames from a color movie are fabricated on holographic recording material by a self-made CGH microfilming system. Secondly, the CGH is fixed on an X-Y moving stage, which is controlled by the system in order to bring the CGH to the appointed position. Thirdly, three primary color lasers are used to reconstruct the CGH. The switch of the lasers is controlled by the system synchronous with the X-Y moving stage. The color video with high quality can be obtained after filtering the three primary color reconstructed wavefronts. The experimental results demonstrate that the proposed dynamic color holographic display method is effective. It has practical application value in high-quality CGH display.

15.2: Design and Realization of Full‐Color VHG Holographic Waveguide Display

To realize the chromatic display function of VHG holographic waveguide display system, we firstly study the preparation process and holographic peformance of color‐sensitive acrylate based photopolymer. Based on the prepared photopolymer, we fabricated the RGB holographic waveguide device with the multiwavelength laser exposure method. Thus, for verifying the display function of the prepared device , the chromatic holographic waveguide near‐eye display module using the LCoS projector engine was developed. The application potential of the color‐sensitive photopolymer in holographic waveguide was also demonstrated.

15.4: Holographic Waveguide Display with Large Field of View Based on Volume Holographic Grating

The field of view of waveguide display systems based on volume holographic gratings is often limited by the grating diffraction response bandwidth, which still cannot meet people's needs for large field of view displays. In order to expand the viewing angle of the waveguide display, the influencing factors of the viewing angle of the waveguide display are analyzed based on the strictly coupled wave theory model, and a double‐layer volume grating waveguide structure that can effectively expand the diffraction response bandwidth is proposed. The grating is prepared by the variable‐angle fractional exposure method, and the holographic waveguide display system is built. The results show that the horizontal and vertical viewing angles of the display system can be expanded to 33° and 22°, respectively, and the diagonal viewing angle is 40°.

Holographic near-eye display system with large viewing area based on liquid crystal axicon.

In this paper, a liquid crystal axicon based holographic near-eye display system with large viewing area is proposed. The viewing area of the system is extended by implementing the liquid crystal axicon. The error diffusion algorithm is used to calculate the computer-generated hologram (CGH). When incident on the liquid crystal axicon placed at the back focal plane of Fourier lens, the reconstruction light modulated by the CGH is deflected into two directions resulting in a viewing area extension. Meanwhile, to illustrate the potential of the proposed system, two-dimensional viewing area extension is demonstrated. It combines the frequency spectrum shift with the proposed system and achieves a double expansion of the horizontal viewing area and three-times expansion of the vertical viewing area. Feasibility of the proposed system is verified by optical experiments. The proposed system has potential applications in holographic augmented reality (AR) display.