In this paper, a new structure of horizontal parallax light field 3D floating image display system was proposed. The structure consists of pico-projectors, Fresnel lens, micro-lens array and sub-lens array with freeform shape. By the functions of optical components, each light field of projectors could be controlled as a fan ray, which has high directivity in horizontal and wide scattered angle in vertical. Furthermore, according to the reverse light tracing and integral image display technique, horizontal parallax floating 3D could be demonstrated in the system. Simulated results show that the proposed 3D display structure has a good image quality and the crosstalk is also limited below 22.9%. Compared with other 3D technologies, this structure could have more benefits, including displaying real high resolution floating image, unnecessary of physical hardware on the image plane, scalability of large size system, without the noise from spinning component, and so on.
The liquid crystal lenses system, which could be electrically controlled easily for autostereoscopic 2D/3D switchable
display was proposed. The High-Resistance liquid crystal (HRLC) lens utilized less controlled electrodes and coated a
high-resistance layer between the controlled-electrodes was proposed and was used in this paper. Compare with the
traditional LC lens, the HR-LC Lens could provide smooth electric-potential distribution within the LC layer under
driving status. Hence, the proposed HR-LC Lens had less circuit complexity, low driving voltage, and good optical
performance also could be obtained. In addition, combining with the proposed driving method called dual-directional
overdriving method, the above method could reduce the switching time by applying large voltage onto cell.
Consequently, the total switching time could be further reduced to around 2second. It is believed that the LC lens system
has high potential in the future.
Now, numerous types of 3D display have been developed or under-developing. However, most of them present
stereoscopic images in a space with limited distance from the physical screen. A display which can deliver stereoscopic
images in the free space and satisfies the touching sense of viewers is always expected. As a result, we proposed a
floating image device with auto-stereoscopic display and viewer tracking technology. The key technology includes that
the optical projected lenses with wide view angle which exceeds 30 degrees, the optimized parameters of 2 views
auto-stereoscopic display which fits the viewing specifications and the viewer tracking technology which can update the
corresponding image of the particular view angle in real time. The novel display is the other choice for consumers
especially for product exhibition, user interface of kiosk and a kind of apparatus of video conference, etc.
To reduce the number of views required for a super multi-view (SMV) display, two or more views are generated with an
interval smaller than the pupil diameter, only around a viewer's left and right eyes. The positions of the views are
changed referring to the viewer's eye positions to increase viewing freedom. The reduced-view SMV display is
implemented using a lenticular-type three-dimensional (3D) display. A cylindrical lens constituting a lenticular lens
projects a group of pixels of a flat-panel display to generate a group of views. The pixel group generating the left view
group and that generating the right view group through an identical cylindrical lens are spatially separated to separate the
view groups. The left and right pixel groups for different cylindrical lenses are interlaced horizontally on the flat-panel
display. A prototype reduced-view SMV display was constructed. Each view group consisted of eight views, and the
interval of the views was 2.6 mm. An LCD panel with a slanted subpixel arrangement was used. The screen size was
2.57 in, and the 3D resolution was 256 × 192 pixels. A USB camera was attached to the SMV display to detect the
viewer's position. The frame rate of face detection and image updating was 30 Hz.
The moiré pattern is caused by the spatial interference of two regular pattern structures. In the case of an
autostereoscopic display, it's caused by the overlap of the parallax barrier and the black matrix among pixels of FPD. To
minimize the moiré effect, we simulate the relationship of brightness distribution and various design parameters of the
parallax barrier. According to the simulation results, a combination of multiple parameters was chose to obtain a moiré
free autostereoscopic display based on the concept of mutual compensation among the design parameters. After the
detailed simulation, experiments of the final design were made to verify the performance of the display.
A multiview autostereoscopic LCD display with a localized 2D/3D switching function is developed based on the
actively switchable parallax barrier technology. This switchable barrier comprises of an electro-optically switchable
liquid crystal (LC) and a microretarder. Polymer dispersed liquid crystal (PDLC) with switchable clear and diffusing
states and twisted nematic liquid crystal (TNLC) with polarization switching function are used as switching devices. The
microretarder is prepared by self-developed multibeam laser scanning process, which is clean, friendly to the
environment, and easy for scale up and mass production. The influence factors on the image qualities of 3D displays
based on LCD panel technology are analyzed and discussed. Some solutions have proposed to solve the commercial
application issues.
A novel autostereoscopic display system, the Integrated-Screen autostereoscopic display system, has been developed to
substantially increase the total number of pixels on the screen, which in turn increase both the resolution and number of
view-zones of the 3D display. In this system, a series of miniature projectors are arrayed and the projection images are
tiled together seamlessly to form an image of ultra high resolution. For displaying 3D images, a lenticular screen with
pre-designed tilted angle is used to distribute the pixels into the plural view-zones. In this paper, an Integrated-Screen
autostereoscopic display system with 30" screen in diagonal and 15 view-zones is presented. The total resolution of the
tiled image is 2930×2700, which is much higher than traditional Full HD display, and the resulted 3D resolution in
each view-zone is 880×600.
For a spatial-multiplexed 3D display, trade-off between resolution and number of view-zones are usually unavoidable
due to the limited number of pixels on the screen. In this paper, we present a new autostereoscopic system, named as
"integrated-screen system," to substantially increase the total number of pixels on the screen, which in turn increase both
the resolution and number of view-zones. In the integrated-screen system, a large number of mini-projectors are arrayed
and the images are tiled together without seams in between. For displaying 3D images, the lenticular screen with predesigned
tilted angle is used for distributing different viewing zones. In order to achieve good performance, we design a
brand-new projector with special lens set to meet the low-distortion requirement because the distortion of the image will
induce serious crosstalk between view-zones. The proposed system has two advantages. One is the extensibility of the
screen size. The size of the display can be chosen based on the applications we deal with, including the size of the
projected pixel and the number of viewing zones. The other advantage is that the integrated-screen system provides
projected pixels in great density to solve the major problem of the poor resolution that a lenticular-type 3D display has.
Different fabrication methods, such as chemical process, laser heating method, etc., can be used to make
micro-retarder plates. In this paper, a CO2 laser scanning system is applied to produce a serious of line patterns on
the commercial compensator (or the retarder film, such as PC film, PVA film, or Arton film, etc.) to make
micro-retarder plates, which are important optical components in stereoscopic 3D displays. Our study is focused
on the development of high quality fabrication method, for example, the relationship of a well-defined stripe
boundary with the CO2 laser process under single beam or multiple beams. The laser scanning system in this paper
is installed with an orthogonal pair of precise translation stages, a steadily controlled laser power output, and an
adjustable spot-size optical head to make patterns of micro-retarder plates for stereo-LCTVs up to 42 inches.
A microretarder for stereoscopic display is a film consisting of horizontal or vertical stripes with alternating null
and half-wave phase retardation states. An LCD with a microretarder attached on the front side can display good-quality
stereoscopic images when viewed with polarization glasses. It is now the easiest and cheapest way to present
stereoscopic images on a flat-panel display. However, the space caused by the glass between the retarder layer and the
LC layer of the panel seriously limits the vertical view angle, which, in turn, limits the application of this technology. In
this paper, a process for thin-film microretarder is developed using reactive liquid crystal. The material and the process
are essentially compatible with current LC panel processes. Since the thin-film microretarder is to be fabricated in the
cell of an LC panel, the retarder layer and the LC layer can be fabricated as close to each other as possible. A nearly
unlimited 3D view angle can be achieved for the display.
The properties of periodicity and linear separation/combination of optical retardation are adopted to develop the Random-Retardation-Encoding anti-counterfeiting technology. In the experiments of this paper, the authentication pattern was divided into two parts with different random retardation distribution. The two parts of random retardation pattern were fabricated on two separate films. One of them can be used as the authentication tag, and the other is used for the identification of the authentication tag. Because the resolution of the random retardation pattern can be made very high, it's very hard to counterfeit the authentication tag without knowing the original design pattern. In addition, the transparency property of the retardation film makes it easy to be integrated with other anti-counterfeiting method, e.g. it can be laminated on a hologram without destroying the visual performance of the hologram while the authentication function of the retardation film is still maintained.
Entertainment is usually considered an important application for stereoscopic display technologies. In order to provide more realistic and exciting VR effect, it is desirable to have as large screen as possible. However, the screen sizes of current autostereoscopic display technologies are limited by either the displaying panel or the optical components. In a government-sponsored project, we designed and fabricated a novel projection screen for autostereoscopic display. The screen consists of two layers of microretarder and a layer of polarization reserved diffuser. Both the screens and the projectors can be arrayed to build a large autostereoscopic display system. Curved or multi-plane screens are also possible. This kind of autostereoscopic display screen has the advantages of ease to scale up, low cost and no precise alignment between the projectors and the screen required. In this paper, the manufacture considerations of such a screen are studied and the experimental results are presented.
The ghost-image issue induced by crosstalk in stereoscopic, especially autostereoscopic, display systems has been believed to be a major factor to jeopardize stereopsis. Nevertheless, it is found that in some cases the stereopsis remains effective even with serious crosstalk. In fact, many other factors, such as contrast ratio, disparity, and monocular cues of the images, play important roles in the fusion of stereo images. In this paper, we study the factors in an image that may affect stereo fusion, and provide a macroscopic point of view to get a reasonable criterion of system crosstalk. Both natural and computer-generated images are used for detailed evaluation. Image processing techniques are adopted to produce desired characteristics. The results of this research shall be of reference value to content makers of stereoscopic displays, in addition to their designers.
In the design of an autostereoscopic display system we usually deal with trade-offs among resolution, number of viewing- zones, and brightness. A viewer-tracking-based autostereoscopic display, with a micro-retardation array for image splitting, can achieve reasonable balance among these properties simultaneously. However, the bulkiness due to the hard-to-decrease f-number of the field lens used to direct light to the viewer presents a problem. In this paper, we introduce a newly-developed flat-panel autostereoscopic display system. Instead of using a large format field lens, a precise lenticular plate, with an LCD tracking panel on its back focal plane, is attached to the LCD image panel and acts as both the backlight and the tracking device. The total depth of the system is condensed to the order of several centimeters under such a configuration. Both micro-retardation array and micro-prism can be used as the images splitter of such a system. In order to avoid the crosstalk caused by the optical leakage between adjacent columns, a vertically interlaced blazed grating should be used in place of the striped-wise micro-prism fabricated by mechanical machining. A display with 6' screen in diagonal is constructed for feasibility study, in which a micro-retardation array is used as the image splitter and combination of micro-retardation array and a polarizer is used to stimulate the tracking LCD. Detailed performance evaluation of the system is addressed.
3D image display devices have wide applications in medical and entertainment areas. Binocular (stereoscopic) imaging without glasses, especially spatial-multiplexed displays such as lenticular display, barrier strip display, and single-lens stereoscopic display, is one of the most powerful and popular ways for life-like presentation of our 3D environments. The definition and relationship of the image contrast and viewer crosstalk are reviewed and clarified. They are measured and compared on three different types of 3D display systems, including shutter-glasses stereoscopic display, image splitter autostereoscopic display and dual-panel autostereoscopic display.
A micro-retardation array is a plate consisting of two or more optical retardation states that are micro-patterned within different regions of the plate. A LCD panel with the micro-retardation array can be used to display stereoscopic images watched with or without special glasses by encoding right-eye image and left-eye image with periodically horizontal stripes of different polarization states. For example, the odd rows of stripes are assigned to have zero retardation and the even rows of stripes with a half- wavelength retardation or vice versa. The width of each stripe is of the order of hundreds of microns. This paper describes a fabrication process of micro-retardation array with high contrast ratio, well-defined stripe boundary and green process. The fact that the retardation property of polymer film will be changed by heat process is used in this fabrication process. It is shown that by accurately controlling the power and spot-size of a CO2 laser, the retardation property of a polymeric film, such as PC and ARTON can be tailored within a localized area without altering the retardation of the untreated areas. In addition, the contrast ratios of micro-retardation array are measured and analyzed, the performance of an autostereoscopic display system using the micro-retardation array is also described.
A diffuser with large horizontal and vertical diffusion angle is a key component for the screen of a projection display. On the other hand, an autostereoscopic projection display needs a small horizontally diffused and large vertically diffused diffuser. A commercial LSD composed of cylindrical-based grains can be used to meet this requirement. Nevertheless, as the diffused intensity profile of a LSD is Gaussian-like, a LSD in many cases can cause either ghost imaging or black stripes while applied to the screen of autostereoscopic displays. Lenticular plates can produce a near flat-top diffusing profile when the divergence angle is small. For example, a lenticular plate with a 5 degrees divergence can be shown in theory to have only a 2.1 percent non-uniformity. However, as the curvature of the lenticular is very small, it becomes very difficult to fabricate such a lenticular plate. This paper reports a novel approach to modify a lenticular plate that was originally with a large divergence angle to a plate with a desired smaller divergence angle, without destroying the surface quality and maintaining good uniformity. The lenticular plate fabricated by using this approach was used as a screen diffuser of a projection-based autostereoscopic display, and the luminance of the screen viewed from different angles was measured.
A windshield laminated hologram is an important application in automotive head-up displays. Properties of these holograms generally produce changes during processing. To predict changes accurately, the diffraction efficiency measurement etc. were apparently used to characterize their diffraction properties. This paper considers the actual structure of a windscreen which is composed of photopolymer hologram within the laminate. The photopolymer hologram, which was sandwiched between a polyvinylbutyral layer and glass ply, was treated at high temperature up to 140 degree(s)C and about 12.5 kg/cm2 pressure; as used in a standard windscreen production process. The fringe planes of laminated hologram are generally sensitive to external parameters during process, such as pressure effects. In this paper, the pressure effect on diffraction properties is investigated to characterize windshield laminated photopolymer holograms. A theoretical model was proposed to approach the pressure effect in fringe plane of laminated hologram. A comparison of nonslanted and slanted holograms are analyzed with experimental data.
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