Synthesis and photoluminescence studies of Ba(Gd,Ln)B_9O_(16):Eu^(3+)(Ln=La,Y) phosphors for n-UV LED lighting and display devices

BaGdB9O16：Eu^3＋ and Ba（Gd,Ln）B9O16：Eu^3＋（Ln=La, Y） phosphors were synthesized by solid state diffusion method. The X-ray diffraction, scanning electron microscopy（SEM） and photoluminescence properties were investigated. The as-synthesized BaGdB9O16：Eu^3＋ and Ba（Gd,Ln）B9O16：Eu^3＋（Ln=La, Y） phosphors showed strong red emission under ultraviolet light excitation. By partially substituting Gd^3＋ by La^3＋ and Y^3＋ ions in the host BaGdB9O16：Eu^3＋ materials, the maximum emission intensity was observed for the optimum composition of BaGd0.91La0.8B9O16Eu0.01 phosphor. The experimental results indicated that the Eu doped BaGdB9O16 and Ba（Gd,Ln）B9O16（Ln=La, Y） phosphors were promising red phosphors, which might find potential applications in near-UV excited LED lighting as well as display devices. Comparison of as-synthesized phosphors with standard phosphor used in CFL（compact fluorescent lamp） was also done. Energy transfer mechanism of Gd^3＋ to Eu^3＋ was also discussed in this paper.

NOVEL VOLUMETRIC THREE-DIMENSIONAL DISPLAY SYSTEM

A novel volumetric three-dimensional（3-D） display system is developed based on the human eye persistence and the system fuses a time-series of image slices into a single hologram like 3-D aerial image. The system design is introduced and key components are described. Experimental results show that the 3-D system can guide people freely walk around the display to inspect the true 3-D image without goggles.

Decoding the Moon Phase Display Device over the Front Dial of the Antikythera Mechanism

The Antikythera mechanism is the most famous ancient astronomical calculator. The damaged excavation is a critical constraint for decoding the mechanism completely. By the systematic reconstruction design methodology, all feasible designs of the moon phase display device, which is one of the unclear mechanisms of the Antikythera mechanism, are reconstructed. These designs, including ordinary gear trains and epicyclic gear trains, are the simplest designs and satisfy the surviving evidence. The Antikythera mechanism and its reconstruction designs presented by LIN and YAN are introduced first. Three pointer types of the Antikythera mechanism are concluded based on their display motions and the orientation of the mechanism. In accordance with the analysis of the available interior reconstruction designs and the surviving evidence, four feasible designs of the moon phase display device are generated. All of them utilize the ball pointer with black and white that rotates around the radial axis to show cyclic moon phase. Two of these four feasible reconstruction designs are driven by one input source, and their bronze disks are fixed and rotatable respectively. Both of the remaining reconstruction designs are driven by two input sources, and their bronze disks are rotatable. Therefore, the four reconstruction designs of the moon phase display device reveal all possible display conditions of the moon phase pointers and the possible purposes of the bronze disk.

Analysis of optical characteristics of modulation devices with square and circle pixels for 3D holographic display

With the development of the micro/nanolithography, the optic-optic or optic-electronic modulation devices with different pixel shapes and sizes can be used for three-dimensional （3D） dynamical holographic display. The influence of different parameters of the modulation devices on the image quality of the 3D reconstructed object is analyzed for two cases： the phase-only computer-generated holography （CGH） and the complex amplitude CGH. The results quantitatively show that the pixel shape of the modulation devices will affect the quality of the holographic image.

Crosstalk reduction in multi-view autostereoscopic three-dimensional display based on lenticular sheet

A method to reduce crosstalk in multi-view autostereoscopic three-dimensional （3D） displays based on the lenticular sheet is proposed. Correcting the luminance values of each parallax image displayed on the display screen is employed. We analyze the causes of crosstalk. We deduce the formulas of crosstalk reduction according to the relationship between crosstalk coefficients of each parallax image observed through the lenticular sheet, luminance values of each parallax image displayed on the display screen, and luminance values of each parallax image observed through the lenticular sheet at each viewing position. Experimental results verify the effectiveness of the proposed method.

Multi-view 3D display with high brightness based on a parallax barrier

A multi-view three-dimensional （3D） display provides a more realistic experience than a two-view 3D dis- play. Therefore, a multi-view 3D display with high brightness based on a parallax barrier is proposed. The parallax barrier in the 3D display has a gradient transmittance with enhanced frequency character- istic, which indicates that the aperture ratio of the parallax barrier can be increased, thereby improving brightness. Gradient transmittance is also helpful in reducing crosstalk. A prototype of the 3D display is developed. Experimental result shows that the 3D display has higher brightness than a conventional display. In addition, crosstalk is limited at a low level.

Temperature-dependent optical response of phase-only nematic liquid crystal on silicon devices

Wavelength-dependent birefringence and dielectric anisotropy.two major optical properties of the nematie liquid crystal materials used in phase-only liquid crystal on silicon（LCOS） devices,are measured as a function of operating temperatures.The dynamic phase modulation depth and threshold voltage of these phase-only LCOS devices are also measured in the corresponding temperature range and compared with theoretical predictions.The results show that the dynamic response time can he reduced significantly by an appropriate increase ol device operative temperature,while the necessary device elements,such as phase modulation depth and threshold voltage,can be maintained at the same time.

A robust photometric calibration framework for projector-camera display system

A novel photometric calibration framework is presented for a projector-camera （ProCam） display system, which is currently under booming development. Firstly, a piecewise bilinear model and five 5-ary color coding images are used to construct the homography between the image planes of a projector and a camera. Secondly, a photometric model is proposed to describe the data flow of the ProCam display system for displaying color images on colored surface in a general way. An efficient self-calibration algorithm is correspondingly put forward to recover the model parameters. Aiming to adapt this algorithm to different types of ProCam display system robustly, a 3× 7 masking coupling matrix and a patches image with 1024 color samples are adopted to fit the complex channel interference function of the display system. Finally, the experimental results demonstrate the validity and superiority of this calibration algorithm for the ProCam display system.

Speckle analysis in laser scanning display system

The theory of speckle formation in laser scanning display system is established based on the averaging effect of eye response as laser beam scanning through an eye resolution spot. It is analyzed that speckle reduction can be obtained by averaging states of speckle during scanning. The theoretical results show that a smaller correlation length of screen surface and the narrowing of laser beam in scanning direction can reduce speckle contrast for this system.

Parametric optimization method for the design of high-efficiency free-form illumination system with a LED source

A parametric optimization method is proposed in the design of a high-efficiency free-form illumination system. The proposed method is intended to provide rectangular uniform illumination with a light emitting diode （LED） source. An initial illumination system is first constructed and parameterized. The parameters of the initial system are optimized according to actual simulation results, and one design sample is presented. A liquid crystal on silicon （LCoS） micro-projector test module is fabricated and tested based on the design sample. Compared with the conventional micro-projectors using rotational symmetry devices, the micro-projector system designed with the parametric optimization method can send 1.65 times the source power to the LCoS active area with a 4：3 target ratio, and the unilormity reaches 98%.

Simplification of integral imaging system by using a lenticular lens array

Integral imaging is a 3D display technology without any additional equipment. A new system is proposed in this paper, which uses a lenticular lens array to replace the lens array in the conventional integral imaging system. The lenticular integral imaging system reduces the complexity and the price of integral imaging system. The positive characteristics of conventional integral imaging system, such as full parallax and quasi-continuous view points, are still kept on the proposed system in horizontal direction. Optical results show that the time for calculating the elemental images is reduced by 25% compared with the conventional one. The resolution of integrated image in vertical direction is 4 times higher than that of conventional system. This proposed system opens a new way on application of integral imaging.

Voltage-controlled optical filter based on electrowetting

In this letter, we propose a voltage-controlled optical filter based on electrowetting. The device is made of a transparent cubic cell filled with two immiscible liquids having three indium tin oxide electrodes fabricated on the bottom substrate of the cell. A conductive droplet carrying a color filter is placed on the ITO electrode and the surrounding liquid is density-matched silicone oil. Under zero bias, the droplet is placed in the middle of tile substrate and white light passes through the filter and we can see red light on the screen. When a voltage is applied to the device, the filter moves with the liquid based on electrowetting effect, we can see the white light on the screen. Due to the movement of the liqnid, our device functions as an optical switcher. The switch trine of the device is -70 ms. The proposed device has a wide application in optical communication. electronic display, and optical switch.

Motion-compensated interpolation for face-centered-orthorhombic sampled video sequence

Face-centered orthorhombic（FCO） sampling can be implemented more easily on CMOS image sensors than on other video acquisition devices.The sampling efficiency of FCO is the highest among all threedimensional（3D） sampling schemes.However,interpolation of FCO-sampled data is inevitable in bridging human perception and machine-vision algorithms.In this letter,the concept of motion compensation is borrowed from deinterlacing,which displays interlaced videos on progressively scanned devices.The combination of motion estimation based on intrafield interpolated frames and motion-compensated interfield interpolation is found to provide the best performance by evaluating different combinations of motion estimation and interpolation.

Double depth-enhanced 3D integral imaging in projection-type system without diffuser

Integral imaging is a three dimensional(3D)display technology without any additional equipment.A new system is proposed in this paper which consists of the elemental images of real images in real mode(RIRM)and the ones of virtual images in real mode(VIRM).The real images in real mode are the same as the conventional integral images.The virtual images in real mode are obtained by changing the coordinates of the corresponding points in elemental images which can be reconstructed by the lens array in virtual space.In order to reduce the spot size of the reconstructed images,the diffuser in conventional integral imaging is given up in the proposed method.Then the spot size is nearly1/20 of that in the conventional system.And an optical integral imaging system is constructed to confirm that our proposed method opens a new way for the application of the passive 3D display technology.