Hang Fan

Optimizing Time-Multiplexing Auto-Stereoscopic Displays With a Genetic Algorithm

A figure-of-merit (FOM) of an auto-stereoscopic display system is introduced and adopted to characterize the system performance. This FOM takes into account of the ratio of the signal to the noise arising from the crosstalk from the adjacent channels as well as the brightness uniformity of viewing areas; hence, it is directly related to the glasses-free 3D viewing comfort. With a steadily improving FOM as a target, the genetic algorithm is applied to optimize the optical system, giving rise to substantially improved characteristics of an auto-stereoscopic display system. The numerical simulation is verified with an experiment of a multi-view auto-stereoscopic display unit. It is shown that the system can provide a high fidelity of the display effect with the crosstalk ratio being reduced from around 5% to nearly 1%, which is a very low value obtainable for an auto-stereoscopic system.

High-quality autostereoscopic display with spatial and sequential hybrid control

A novel design of an autostereoscopic display system with full resolution, low crosstalk, and weak Moiré pattern is presented. The system involves the usage of an LED backlight array and a liquid crystal display (LCD) panel, in conjunction with a Fresnel lens array, to form a 3D optical image system. The finer temporal synchronization is made possible with a dynamic synchronized backlight, so that the scanning of the LCD is in phase with the backlight array. The systematic optimization presents a full HD, or even an ultra HD, display for a single left or right channel. The achieved minimum systematic crosstalk is 2.64%, a sufficiently low value reported so far with an autostereoscopic system.

Full Resolution, Low Crosstalk, and Wide Viewing Angle Auto-Stereoscopic Display With a Hybrid Spatial-Temporal Control Using Free-Form Surface Backlight Unit

A full resolution, low crosstalk and wide viewing angle auto-stereoscopic display is demonstrated with the use of a novel free-form surface backlight (FFSB) technique, in conjunction with a hybrid spatial and temporal control scenario. The overall crosstalk coming from adjacent channels is shown to be lower than 5% even at a wide viewing angle, and minimum achievable crosstalk can be as small as 2.41%. The key element design giving rise to achieving the full viewing angle greater than 45 degrees is also presented.

Quantitative measurement and control of optical Moiré pattern in an autostereoscopic liquid crystal display system

A quantitative description of an optical moiré pattern produced in an autostereoscopic liquid crystal display system is proposed using a contrast sensitivity function. The numerical simulation, carried out in the spatial frequency domain, is applied to a directional backlit, spatially and temporally hybrid controlled display system. The moiré pattern produced from the superimposed binary optical components is examined systematically, and the results show that the visibility of the moiré pattern can be manipulated with proper grating settings. Good agreement between experiment and simulation demonstrates that the proposed theory can be applied as a design guideline to remove the moiré patterns occurring in an autostereoscopic display system.

Pseudo-random arranged color filter array for controlling moiré patterns in display

Optical display quality can be degraded by the appearance of moiré pattern occurring in a display system consisting of a basic matrix superimposed with a functional structured optical layer. We propose in this paper a novel pseudo-random arranged color filter array with the table number arranged with an optimal design scenario. We show that the moiré pattern can be significantly reduced with the introduction of the special color filter array. The idea is tested with an experiment that gives rise to a substantially reduced moiré pattern in a display system. It is believed that the novel functional optical structures have significant impact to complex structured display system in general and to the autostereoscopic and integrated display systems in particular.

Visual effect of a linear Fresnel lens illuminated with a directional backlight.

A linear Fresnel lens illuminated by a directional backlight is studied. The light distribution on the lens surface visualized by a retina is simulated with a Monte Carlo ray-tracing technique, and the visualized display uniformity on the lens surface is found to depend critically on the lens quality as well as on the viewing position away from the light propagation axis. The effect of the light source configuration as well as the deviation of the microstructures of the Fresnel lens from ideal structure are studied. The simulation is verified with an experimental study, and good agreement between numerical and experimental results is obtained. Design guidelines are presented for a backlight-illuminated system to achieve high-quality uniform flat-panel two-dimensional and autostereoscopic displays.

Simulation and Control of Display Uniformity in a Backlight Illuminated Image Array

The relative retinal illumination (RRI) distribution of a display system consisting of arrayed backlight units, focusing lenses, and viewing screen is simulated with Monte Carlo ray tracing method. A random scattering model is applied to describe the optical seam effect in the vicinity of the stitching. RRI distribution on the screen viewed at different locations for an autostereoscopic display system is simulated, giving rise to a quantitative description of display inhomogeneity on the screen. The method to achieve a uniform RRI distribution on the screen is proposed. The numerical simulation is tested with experimental verification, and good agreement is obtained. The simulation, experiment, and measurement can be applied as design guidelines for autostereoscopic display, integrated imaging display, and other novel backlight illuminated optical systems.

Displaying a full high-definition, high-quality 3D image without glasses

Autostereoscopic displays, which produce an illusion of depth in images without requiring the viewer to wear special glasses, have long been regarded as a desirable improvement to existing 2D display technology for entertainment, industry, and research. Ideally, a 3D viewing system would be compatible with current liquid crystal displays (LCDs). Existing systems include parallax barrier and lenticular techniques, which allow each eye to see different images, creating a sense of depth.1–3 However, these suffer from technical challenges, including reduced resolution, limited viewing angle, and unsatisfactory crosstalk.4 Various approaches have been tried to improve autostereoscopic displays.5–7 Directional backlight solutions are able to preserve full image resolution, but their viewing angles or volumes remain relatively limited. Low crosstalk can also be achieved for a given viewing point, but it remains a challenge to keep it low (less than 5%) across the whole viewing zone. Our display consists of control modules, backlight modules, a lens array, and LCD panel, where the green and blue lightpaths represent light intended for the viewer’s right and left eyes, respectively (see Figure 1). LCDs do not produce light themselves, and thus are illuminated from behind (backlit) by modules consisting of white LEDs. The orientation of the liquid crystals determines whether light from the LEDs is transmitted or blocked by the LCDs, and the orientation is controlled by applying an electric field. An array of Fresnel lenses (compact lenses made up of a series of slanted surfaces) in front of the LCD panel orients the light within the viewing zone. We have used an adaptive optical optimization algorithm to design freeform surface backlight (FFSB) modules and a lens array Figure 1. Top view of the autostereoscopic display system showing the control modules, backlight modules (LED bars made up of an LED array and diffuser), liquid crystal display (LCD) screen, and lens array. (Reproduced from original.8)

Simulation approach of display uniformity in a backlight illuminated lens array

The relative retinal illumination (RRI) distribution of a display system consisting of arrayed backlight units, focusing lenses and viewing screen is simulated with Monte Carlo ray tracing method. A random scattering model is applied to describe the optical seam effect in the vicinity of the stitching. RRI distribution on the screen viewed at different locations for an directional backlight display system is simulated, giving rise to a quantitative description of display inhomogeneity on the screen. The method to achieve a uniform RRI distribution on the screen is proposed. The numerical simulation is tested with experimental verification and good agreement is obtained. The simulation, experiment and measurement can be applied as design guidelines for autostereoscopic display, integrated imaging display and other novel backlight illuminated optical systems.

Directional backlight liquid crystal autostereoscopic display: technical challenges, research progress, and prospect(Conference Presentation)

Recent upsurge on virtual and augmented realities (VR and AR) has re-ignited the interest to the immerse display technology. The VR/AR technology based on stereoscopic display is believed in its early stage as glasses-free, or autostereoscopic display, will be ultimately adopted for the viewing convenience, visual comfort and for the multi-viewer purposes. On the other hand, autostereoscopic display has not yet received positive market response for the past years neither with stereoscopic displays using shutter or polarized glasses. We shall present the analysis on the real-world applications, rigid user demand, the drawbacks to the existing barrier- and lenticular lens-based LCD autostereoscopy. We shall emphasize the emerging autostereoscopic display, and notably on directional backlight LCD technology using a hybrid spatial- and temporal-control scenario. We report the numerical simulation of a display system using Monte-Carlo ray-tracing method with the human retina as the real image receiver. The system performance is optimized using newly developed figure of merit for system design. The reduced crosstalk in an autostereoscopic system, the enhanced display quality, including the high resolution received by the retina, the display homogeneity without Moiré- and defect-pattern, will be highlighted. Recent research progress including a novel scheme for diffraction-free backlight illumination, the expanded viewing zone for autostereoscopic display, and the novel Fresnel lens array to achieve a near perfect display in 2D/3D mode will be introduced. The experimental demonstration will be presented to the autostereoscopic display with the highest resolution, low crosstalk, Moiré- and defect- pattern free.