Projection Display Research Articles

Experimental validation of self-focusing image formation for retinal projection display.

The augmented reality (AR) industry requires both aesthetic designs and high performances of AR devices. This complex dilemma challenges R&D groups from all over the world to improve existing systems or propose new, breakthrough designs. The unconventional concept of direct retinal projection display may be one. It is based on see-through holographic retinal projection, with the image being formed via the so-called self-focusing effect. In this paper, we describe an experimental validation of this self-focusing effect and introduce a possible approach of self-focusing performance evaluation. Experimental image formation capability is demonstrated and compared with simulation results. Main present limitations of the concept are discussed, such as pixel addressing design and image resolution/sharpness conflict.

Virtual fire drill system supporting co-located collaboration

Background Due to the restriction of display mode, in most of the virtual reality systems with multiple people in the same physical space, the program renders the scene based on the position and perspective of the one user, so that other users just see the same scene, resulting in vision disorder. Methods To improve experience of multi-user co-located collaboration, in this study, we propose a fire drill system supporting co-located collaboration, in which three co-located users can collaborate to complete the virtual firefighting mission. Firstly, with multi-view stereoscopic projective display technology and ultra wideband (UWB) technology, co-located users can roam independently and watch virtual scenes through the correct perspective view based on their own position by wearing dedicated shutter glasses, thus carrying out different virtual tasks, which improves the flexibility of co-located collaboration. Secondly, we design simulated firefighting water-gun using the micro-electromechanical system sensor, through which users can interact with virtual environment, and thus provide a better interactive experience. Finally, we develop a workbench including a holographic display module and multi-touch operation module for virtual scene assembly and virtual environment control. Results The controller can use the workbench to adjust the virtual layout in real time, and control the virtual task process to increase the flexibility and playability of system. Conclusions Our work can be employed in a wide range of related virtual reality applications.

Dynamic control of laser source current in projection display

Display technology is the main source for humans to obtain information and entertainment. Increased display screen size is a trend, whether on mobile phone or television, and projection display has become increasingly popular in achieving large screen displays. Previous projection display systems have used a traditional light bulb which cannot be modulated, so the power of the display device is constant and the contrast of the display device can only be improved by controlling the size of the aperture in the light path. With the appearance of solid-state light sources, i.e., lasers, the luminance of the light source can be modulated according to the image content so that the power of the light source can be reduced and the dynamic contrast can be improved simultaneously. A method to modulate the power of the laser light source on a frame-to-frame basis in response to the input image data is shown. An ultrahigh contrast is achieved with the laser display. A dynamic contrast of greater than 100,000:1 can be achieved, and the average power consumption of the laser TV can be reduced by about 20% with typical video source material.

Varifocal Occlusion for Optical See-Through Head-Mounted Displays using a Slide Occlusion Mask.

We propose a varifocal occlusion technique for optical see-through head-mounted displays (OST-HMDs). Occlusion in OST-HMDs is a powerful visual cue that enables depth perception in augmented reality (AR). Without occlusion, virtual objects rendered by an OST-HMD appear semi-transparent and less realistic. A common occlusion technique is to use spatial light modulators (SLMs) to block incoming light rays at each pixel on the SLM selectively. However, most of the existing methods create an occlusion mask only at a single, fixed depth-typically at infinity. With recent advances in varifocal OST-HMDs, such traditional fixed-focus occlusion causes a mismatch in depth between the occlusion mask plane and the virtual object to be occluded, leading to an uncomfortable user experience with blurred occlusion masks. In this paper, we thus propose an OST-HMD system with varifocal occlusion capability: we physically slide a transmissive liquid crystal display (LCD) to optically shift the occlusion plane along the optical path so that the mask appears sharp and aligns to a virtual image at a given depth. Our solution has several benefits over existing varifocal occlusion methods: it is computationally less demanding and, more importantly, it is optically consistent, i.e., when a user loses focus on the corresponding virtual image, the mask again gets blurred consistently as the virtual image does. In the experiment, we build a proof-of-concept varifocal occlusion system implemented with a custom retinal projection display and demonstrate that the system can shift the occlusion plane to depths ranging from 25 cm to infinity.

Design of improved prototype of two-in-one polarization-interlaced stereoscopic projection display.

We present an improved two-in-one polarization-interlaced liquid-crystal-on-silicon (LCoS) stereoscopic projection prototype employing a novel prism-array configuration and a specially designed illumination freeform lens group. The parallel prism configuration is designed based on the balance analysis between stereoscopic channels. For further system simplification, the illumination lens group, which consists of three prepositive aspherical surfaces and a single postpositive freeform one, is synthetically obtained from the Monge-Ampère method and feedback optimization. Design results show that the proposed prototype can well solve the problem of stereo-channel separation and integration, and provide both better performance and lower volume. It is proven to have potentiality replacing existing stereoscopic projectors.

Toward transparent projection display: recent progress in frequency-selective scattering of RGB light based on metallic nanoparticle’s localized surface plasmon resonance

A transparent display simultaneously enables visualization of the images displayed on it as well as the view behind it, and therefore can be applied to, for instance, augmented reality (AR), virtual reality (VR), and head up display (HUD). Many solutions have been proposed for this purpose. Recently, the idea of frequency-selective scattering of red, green and blue light while transmitting visible light of other colours to achieve transparent projection display has been pro-posed, by taking advantage of metallic nanoparticle’s localized surface plasmon resonance (LSPR). In this article, a review of the recent progress of frequency-selective scattering of red, green and blue light that are based on metallic nanoparticle’s LSPR is presented. A discussion of method for choosing appropriate metal(s) is first given, followed by the definition of a figure of merit used to quantify the performance of a designed nanoparticle structure. Selective scattering of various nanostructures, including sphere-shaped nanoparticles, ellipsoidal nanoparticles, super-sphere core-shell nanoparticles, metallic nanocubes, and metallic nanoparticles combined with gain materials, are discussed in detail. Each nanostructure has its own advantages and disadvantages, but the combination of the metallic nanoparticle with gain materials is a more promising way since it has the potential to generate ultra-sharp scattering peaks (i.e., high frequency-selectivity).

Wide-FOV Projection Display for Remote Control of Construction Robot

Wide-FOV Projection Display for Remote Control of Construction Robot

Real‐Time Human Shadow Removal in a Front Projection System

AbstractWhen a person is located between a display and an operating projector, a shadow is cast on the display. The shadow on the display may eliminate important visual information and therefore adversely affect the viewing experiences. There have been various attempts to remove the human shadow cast on a projection display by using multiple projectors. While previous approaches successfully removed the shadow region when a person moderately moves around or stands stationary in front of the display, there is still an afterimage effect due to the lack of consideration of the limb motion of the person. We propose a new real‐time approach to removing the shadow cast by a person who dynamically interacts with the display, making limb motions in a front projection system. The proposed method utilizes a human skeleton obtained from a depth camera to track the posture of the person which changes over time. A model that consists of spheres and conical frustums is constructed based on the skeleton information in order to represent volumetric information of the person being tracked. Our method precisely estimates the shadow region by projecting the volumetric model onto the display. In addition, employment of intensity masks that are built based on a distance field helps suppress the afterimage of the shadow that appears when the person moves abruptly. It also helps blend the projected overlapping images from different projectors and show one smoothly combined display. The experiment results verify that our approach removes the shadow of a person effectively in a front projection environment and is fast enough to achieve real‐time performance.

Outfitting Next Generation Displays with Optical Metasurfaces

Optical metasurfaces, composed of ultrathin subwavelength meta-atoms, have enabled flat-optics and corresponding flat optical components such as ultrathin lenses, color filters, and absorbers. Among the plethora of applications currently attracting great interest, next generation display techniques could further benefit from metasurface technology. Thanks to relatively simple mechanisms of amplitude and phase modulation of light by the meta-atoms, many of the recent research achievements in metasurfaces are related to display applications. In this Perspective, we focus on metasurface holograms and colorations for projective and reflective display techniques. First, we briefly introduce the working mechanism of metasurface holograms and colorations and review state-of-the-art techniques in each field from perspective of materials, functionalities, and fabrication methodologies toward real-life display applications. Finally, we conclude on the potential outcome and outlook on this technology and highlight t...

Molecular Dynamics Visualization (MDV): Stereoscopic 3D Display of Biomolecular Structure and Interactions Using the Unity Game Engine.

Molecular graphics systems are visualization tools which, upon integration into a 3D immersive environment, provide a unique virtual reality experience for research and teaching of biomolecular structure, function and interactions. We have developed a molecular structure and dynamics application, the Molecular Dynamics Visualization tool, that uses the Unity game engine combined with large scale, multi-user, stereoscopic visualization systems to deliver an immersive display experience, particularly with a large cylindrical projection display. The application is structured to separate the biomolecular modeling and visualization systems. The biomolecular model loading and analysis system was developed as a stand-alone C# library and provides the foundation for the custom visualization system built in Unity. All visual models displayed within the tool are generated using Unity-based procedural mesh building routines. A 3D user interface was built to allow seamless dynamic interaction with the model while being viewed in 3D space. Biomolecular structure analysis and display capabilities are exemplified with a range of complex systems involving cell membranes, protein folding and lipid droplets.

Upper limb robotic rehabilitation for chronic stroke survivors: a single-group preliminary study.

[Purpose] This study aimed to assess whether robotic rehabilitation can improve upper limb function, activities of daily living performance, and kinematic performance of chronic stroke survivors. [Subjects and Methods] Participants were 21 chronic stroke survivors (19 men; 60.8 years; Mini-Mental State Examination score: 28; onset duration: 10.2 years). Training exercises were performed with a Whole Arm Manipulator and a 120-inch projective display to provide visual and auditory feedback. Once the training began, red and grey balls appeared on the projective display, and participants performed reaching movements, in the assist-as-needed mode, toward 6 directional targets in a 3-dimensional space. All participants received training for 40 minutes per day, thrice per week, for 6 weeks. Main outcome measures were upper limb function (Fugl-Meyer Assessment, Action Research Arm Test, and Box and Blocks Test scores), activities of daily living performance (Modified Barthel Index), and kinematic performance (movement velocity) in 6 directions. [Results] After 6 weeks, significant improvement was observed in upper limb function, activities of daily living performance, and kinematic performance. [Conclusion] This study demonstrated the positive effects of robotic rehabilitation on upper limb function, activities of daily living performance, and kinematic performance in chronic stroke survivors.

Resonant scattering of green light enabled by Ag@TiO2 and its application in a green light projection screen

The ability to selectively scatter green light is essential for an RGB transparent projection display, and this can be achieved by a silver-core, titania-shell nanostructure (Ag@TiO2), based on the metallic nanoparticle's localized surface plasmon resonance. The ability to selectively scatter green light is shown in a theoretical design, in which structural optimization is included, and is then experimentally verified by characterization of a transparent film produced by dispersing such nanoparticles in a polymer matrix. A visual assessesment indicates that a high-quality green image can be clearly displayed on the transparent film. For completeness, a theoretical design for selective scattering of red light based on Ag@TiO2 is also shown.

基于自由曲面阵列的激光投影显示照明系统设计

基于自由曲面阵列的激光投影显示照明系统设计

基于高度信息的自由曲面可编辑投影显示技术

基于高度信息的自由曲面可编辑投影显示技术

Use of the Avegant Glyph Head-Mounted Virtual Retinal Projection Display to Perform Vitreoretinal Surgery

Objective: To evaluate the use of a novel retinal projection display in vitreoretinal surgery. Methods: The Avegant Glyph virtual retinal display, which uses a light-emitting diode and micromirror array to project directly onto the retinas of the user, was evaluated. This unit was modified for better operating room characteristics. It was evaluated by 6 surgeons performing mock vitreoretinal surgeries. Results: The majority reported high 3-dimensional (3-D) depth rendition, little hindrance to communication, and high confidence to perform procedures. Due to a small ocular size, surgeons conveyed that the Glyph provides a novel enhanced view for performing procedures benefiting from simultaneous intra- and extraocular visualization such as scleral depression. Safety analysis by performing fundus autofluorescence after 2 hours of Glyph operation did not reveal any gross qualitative change. Conclusion: Use of the Avegant Glyph to perform vitreoretinal surgery may provide ergonomic advantages, while its visualization and high 3-D stereoscopic depth rendition instill high surgeon confidence to safely perform procedures. We are performing further studies with objective data to validate the potential of this technology.

Laser display system for multi-depth screen projection scenarios.

Proposed is a laser projection display system that uses an electronically controlled variable focus lens (ECVFL) to achieve sharp and in-focus image projection over multi-distance three-dimensional (3D) conformal screens. The system also functions as an embedded distance sensor that enables 3D mapping of the multi-level screen platform before the desired laser scanned beam focused/defocused projected spot sizes are matched to the different localized screen distances on the 3D screen. Compared to conventional laser scanning and spatial light modulator (SLM) based projection systems, the proposed design offers in-focus non-distorted projection over a multi-distance screen zone with varying depths. An experimental projection system for a screen depth variation of 65cm is demonstrated using a 633nm laser beam, 3KHz scan speed galvo-scanning mirrors, and a liquid-based ECVFL. As a basic demonstration, an in-house developed MATLAB based graphic user interface is deployed to work along with the laser projection display, enabling user inputs like text strings or predefined image projection. The user can specify projection screen distance, scanned laser linewidth, projected text font size, projected image dimensions, and laser scanning rate. Projected images are shown highlighting the 3D control capabilities of the display, including the production of a non-distorted image onto two-depths versus a distorted image via dominant prior-art projection methods.

Full-color holographic projection display system featuring an achromatic Fourier filter.

We propose a full-color complex holographic display system design comprised of three R/G/B amplitude-only spatial light modulators and an achromatic Fourier filter. A key feature of the design is a single achromatic Fourier bandpass filter for robust axial R/G/B color matching, whereby the R/G/B holographic image light fields can be three-dimensionally aligned. The synthesis algorithm producing the full-color computer-generated holograms for this system is described and a full-color optical reconstruction of the designed holographic three-dimensional images is experimentally demonstrated.

Perceptually accurate display of two greyscale images as a single colour image.

Life scientists often desire to display the signal from two different molecular probes as a single colour image, so as to convey information about the probes' relative concentrations as well as their spatial corelationship. Traditionally, such colour images are created through a merge display, where each greyscale signal is assigned to different channels of an RGB colour image. However, human perception of colour and greyscale intensity is not equivalent. Thus, a merged image display conveys to the typical viewer only a subset of the absolute and relative intensity information present in and between two greyscale images. The Commission Internationale de l'Eclairage L*a*b* colour space (CIELAB) has been designed to specify colours according to the perceptually defined quantities of hue (perceived colour) and luminosity (perceived brightness). Here, we use the CIELAB colour space to encode two dimensions of information about two greyscale images within these two perceptual dimensions of a single colour image. We term our method a Perceptually Uniform Projection display and show using biological image examples how these displays convey more information about two greyscale signals than comparable RGB colour space-based techniques.

3-9 リアプロジェクションディスプレイにおける全反射フレネルレンズの光学設計と特長(第3部門 情報ディスプレイ1)

3-9 リアプロジェクションディスプレイにおける全反射フレネルレンズの光学設計と特長(第3部門 情報ディスプレイ1)

High resolution real-time projection display using a half-overlap-pixel method

A high resolution real-time projection display was realized by a half-overlap-pixel method in which the intensity was determined by two phase-only computer generated holograms that were obtained analytically. The basic principle of the method is introduced and the numerical simulations that were performed are explained. The results verified that an accurate intensity distribution was achieved successfully with high quality, and the calculation speed was fast enough for real time display. We suggest that it is potentially a promising approach for future displays.