Prism-pattern design of an LCD light guide plate using a neural-network optical model

This paper proposes a neural-network optical model for a backlight module of a liquid crystal display (LCD) to expedite the design of the light-scattering prism-pattern of its light guide plate (LGP). First, the prism surface of a light guide plate is divided into several equal regions. Then the neural-network optical model is implemented using a back-propagation neural network to establish the relationship between the distribution density of the prism pattern and the exiting-light luminance of the LGP at each region. The input–output patterns for the neural network training and verification are generated using orthogonal arrays and ASAP simulation. Then a for-loop computational algorithm is executed to search an approximately optimal distribution density of the prism pattern using the neural-network optical model such that high luminance uniformity is achieved. It is demonstrated by the case study of a 13 in. LCD backlight module that luminance uniformity could reach 93.1%. Thus it can be concluded that the developed neural-network optical model effectively expedites the LGP prism-pattern design.     

Zemax软件在取样光栅对设计中的应用

 光束取样光栅(BSG)是一种重要的用于光束取样诊断的衍射光学元件。以2块取样光栅代替单块光栅作为初始光学结构,运用Zemax光学设计软件采用分步优化的方法设计了具有消像差功能的光栅对结构,此方法比采用Matlab语言编程计算的方法消像差更快捷、更灵活,同时可以验证程序计算结果的正确性。设计结果显示：再现的会聚光经2块光栅衍射后在像平面上点列图中的均方根半径仅为0.506μm,单块取样光栅的均方根半径则为7.284μm,说明2块光栅能够做到像差互相矫正,其像质明显好于单块取样光栅。另外,设计出的双光栅光学系统,可进行远场光斑质量检测,为激光束性能的在线诊断提供了行之有效的技术支持。     

Light scattering on ultrathin capillaries

In recent experiments, very low amplitudes of light scattering were reported for a tightly focused laser beam on a glass microcapillary. This result may be of great importance for single molecule detection in liquids. In the present paper, a theoretical study of the problem of light scattering of a focused laser beam on a cylindrical glass capillary is given. The numerical calculations are based on an exact electrodynamic treatment of the whole problem, including vector effects of the electromagnetic field of the laser beam. It is shown that under favorite conditions (inner and outer radius of the capillary, perfect adjustment of the laser beam) the intensity of the back-scattered light may be extremely low.     

Fabrication of dual brightness enhancement structures on light guide plates using UV roll-to-plate imprinting lithography

We proposed a roll-to-plate UV imprinting lithography (RPIL) process for fabricating dual brightness enhancement structures on light guide plates (LGPs). The refractive indices of the UV resin for layers imprinted on the LGP were investigated through computer-aid optical analysis and experiments. The refractive indices of the resins ranged from 1.49 to 1.69, and flat films such as polyethylene terephthalate (PET) films used by the media layer have better on-axis luminous intensity enhancement rate rates. Using the proposed process, several vertical prismatic structures on the LGP achieved a formability rate of 97% respectively, and the luminous intensity enhancement rate exceeded 2.1, which is almost the same as that of 3M's dual-prism film. This study demonstrates the potential of our proposed process for fabricating multi-layer of microstructures on the LGP.     

Near-field acoustic intensity measurements using an accelerometer-based underwater intensity vector sensor

An accelerometer-based underwater acoustic intensity vector sensor is used to measure the acoustic nearfield of a single spherical source, and a pair of sources that vibrate in or out of phase with each other. The intensity sensor consists of co-located pressure and inertial sensors within a neutrally buoyant probe body. The design of this probe has been published previously. The measurements were performed in a large tank at a frequency of 5 kHz for two sources of different sizes, corresponding to ka values of 0.7 and 1.2 respectively, where k is acoustic wavenumber and a is the source radius. By way of validation, the acoustic intensity field from two closely spaced, interacting spherical radiators is predicted using the exact theory of the translational addition theorem for spherical wave functions. The predictions using this theory compare favorably well with the measured intensity field. Beam pattern and calibration data obtained for the intensity sensor suggest that underwater acoustic intensity generated by simple and complex sources can be measured to an accuracy of ±1 dB provided that ka is less than approximately 0.2.     

Optical characteristics of LGP depending on the scattering pattern orientation for flat-type LED lighting

In flat-type light-emitting-diode (LED) lighting systems, a planar light is formed using a luminance source positioned on the side of the system and light guide panel (LGP) or reflecting plates. Thus, such systems are favorable for their thinness, which allows a relatively small number of LEDs to be used. However, the application of a high-power LED light to a large-area lighting system yields Lambertian luminaires; therefore, a point or a discomfort glare is produced, which generally causes degradation of the luminance efficiency and uniformity. In this study, we solved the problems of luminance non-uniformity and inefficiency by adjusting the orientation of an applied LGP scattered pattern and removing the remaining glare. Through computer simulation, optical characteristics that increase the efficiency even in the case of low-output LEDs were found. Specifically, a scattered pattern vertically oriented relative to the direction of the incident light improves the luminance uniformity at the side of the system, while a scattered pattern oriented parallel to the direction of the incident light plays the role of a waveguide. We implemented a flat-type LED lighting system by fabricating a large-area LGP based on the computer-simulation results and using an extremely sensitive laser. The optical characteristics observed using the laser-processed LGP were identical to those obtained in the computer simulation. Therefore, for large-area flat-type LED lighting systems, we confirmed that adjusting the orientation of the LGP scattered pattern can increase the luminance efficiency and uniformity.     

Variable-radius focused optical vortex with suppressed sidelobes

We propose a design for a phase mask for generating an optical vortex with suppressed sidelobes in the focal plane where the radius of the intensity ring is variable. A radial modulation added to conventional phase mask exp(iltheta) projects the light diffracted from different annular zones into a single intensity ring in the focal plane.     

光导板中新型衍射元件的数值模拟研究

基于严格耦合波理论,数值计算了一种在闪耀斜面镀膜的亚波长光栅结构,并首次提出将该光栅应用于光导板的设计中,使光导板衍射的RGB光束无需经过滤色片,直接透射相应的像素点。在数值计算中,设定入射光为TE偏振态、入射角为60°、波长为RGB三基色。光栅以有机玻璃为基底,二氧化钛为膜层,并随波长改变周期、闪耀角等参数。计算结果表明,该光栅的一级衍射光可垂直于表面出射,一级衍射效率随膜厚渐变,最高达37%,其余非零级次的衍射效率低于2%。将该特性的光栅应用于新型光导板的数值建模中,并对光栅的制作进行了工艺容差分析,计算得归一化能量的标准差小于1%,总衍射效率接近80%。     

手机导光板熔合微光学阵列研究

为了研究手机侧发光背光模组,理论分析并模拟了在导光板表面直接熔合微光学结构的手机背光系统.结果表明,熔合微光学结构后,手机背光系统的出射光场发生变化,使得部分光线在偏离视场中心55°的方向上会聚,为设计新型集成手机微光学导光板奠定基础.     

Phonon scattering and interstitial clusters in γ-irradiated LiF

The thermal conductivity of pure and Mg-doped LiF single crystals irradiated at room temperature in a Co⁶⁰ source (3–780 Mrad) was measured between 60mK and 70 K. Several phonon scattering mechanisms for extended defects are reviewed and it is shown that experimental results can be understood in terms of two types of interstitial clusters: (a) small spherical clusters whose number density and size depend on the residual impurity content; and (b) large non-spherical clusters of toroïdal shape with a major radius of several hundred Å and minor radius of some tens of Å. For increasing dose, the major radius decreases, the minor radius increases and the rings become increasingly opaque possibly due to the associated strain field.     

光散射聚合物导光板的材料参数设计

光散射聚合物(HSOT)导光板与传统导光板相比具有亮度更高均匀性更好等优点,其性能受材料的影响十分明显。通过蒙特卡罗方法进行光学仿真模拟考察不同材料的导光板照明光线的均匀性差别,研究了光散射聚合物导光板的光学性能受其中掺杂粒子的材料折射率、粒径、浓度的影响规律。通过比较不同材料参数的聚合物导光板的光学性能差别,总结出光散射聚合物导光板的材料设计方法。     

Application of an LM-neural network for establishing a prediction system of quality characteristics for the LGP manufactured by CO2 laser

The light guide plate (LGP) is a part of a backlight module, which evenly spreads light sources in a liquid crystal display (LCD) to eliminate total reflection. Light is transmitted into the LGP, where it is reflected, scattered, and refracted due to the microstructure, which allows light to uniformly enter the panel. Therefore, the design of an LGP micro-structure and processing mode is important for light transmission in an LCD. This study used a CO₂ laser to fabricate a polymethyl methacrylate (PMMA) LGP, applied a Taguchi orthogonal array to set up the experiment, and utilized the data to establish a prediction system. Backpropagation (BP) neural network and the Levenberg–Marquardt (LM) algorithm were integrated to establish a prediction system for LGP processing by CO₂ laser, with the controlling factor as the input parameter, and quality characteristics as the output parameters. After learning and training the network, the prediction error rate of the system was controlled within 5%, demonstrating good predictive validity.     

Double-slot antennas on extended hemispherical and elliptical quartz dielectric lenses

In this paper, the theoretical far-field patterns and Gaussianbeam coupling efficiencies are investigated for a double-slot antenna placed on quartz hemispherical lenses with varying extension lengths. The radiation patterns of the double-slot antenna are computed using ray-tracing inside the lens and electric and magnetic field integration on the spherical dielectric surface. The theoretical results are equally valid for double-dipole, log-periodic, and spiral antennas, and are presented in extension length/radius and radius/. Therefore, the results yield universal design curves for quartz lenses of different diameters and at different frequencies and using different antennas. The results indicate that forsingle units, there exists a wide range of extension lengths (ext. length/radius=0.61 to 0.76) which result in high Gaussian-coupling efficiencies to moderately highf/# systems. Forimaging array applications with high packing densities, an extension length/radius=0.82 to 0.93 (depending on frequency) will result in peak directivity and highest packing density but lower Gaussian-coupling efficiencies.     

Complete Gluonic Phase in Two-Flavour Colour Superconductivity

We study a typical complete gluonic phase （LGP） in two-flavour colour superconductivity （2SC） by calculating the essential cubic and quartic interfering term between the gluonic condensates （Az^（8）） and/Az^（6）） with a gauged NJL model. It is proven that the coefficients of the cubic interfering term and the vacuum contributions of the cubic and quartic interfering term are all equal to zeroes. The coefficients of the quartic interfering term and the /Az^（6）） ＇s quartic self-interaction term at stationary points of Larkin-Ovchinnikov-Fulde-Ferrell （LOFF） phase are calculated. Comparisons among the effective potentials of LOP, g2SC and LOFF phase indicate that LOP could be the genuine ground state of 2SC for some reasonable paxameters.     

等离子体天线色散关系和辐射场数值计算

研究了电磁波沿轴向对称柱形等离子体天线传播的特性、色散关系及辐射方向图、增益等天线参数.通过对腔体材料介电系数、内外半径、等离子体密度、碰撞频率等参数的分析，结果表明要减小波沿等离子体天线传播的衰减，应当增加等离子体密度，减小碰撞频率，增加等离子体半径，减小腔体厚度，采用介电系数较小的材料.计算了在不同参数条件下，等离子体天线的辐射方向图、增益的变化，这些结果对于等离子体天线的设计很有参考价值. 关键词： 等离子体天线 色散关系 增益 辐射方向图     

X-ray laser experiments using double foil nickel targets

New target geometries for collisional excitation X-ray laser experiments (in nickel) were proposed, analyzed, and experimentally studied on the Glass Development Laser (GDL). Experiments using a short line focus lens with new target geometries showed general agreement with predictions. The new geometries are designed to yield a higher gain and reduced refraction due to: (1) a higher plasma density, (2) a wider lateral density profile, and (3) a concave lateral density profile. These new geometries were: (1) two parallel exploding (thin) foils, irradiated from one side only, (2) two ablating (thick) foils, one of which is irradiated on its inner face, and (3) an exploding foil in front of an ablating foil, irradiated by a single laser beam incident on the thin foil. New experiments with a long line focus are in progress. The intensity ratio of Ne-like and F-like Ni lines is used to deduce the temperature, and these results together with the absolute intensity, yield the density profile. The results show improvement achieved with the new target geometries: the density is higher (leading to a higher gain), and the concave density profile results in collimation rather than divergence of the X-ray laser beam. Theoretical developments included: (1) prediction of high gain on new type transitions in neon like ions involving the excitation of an inner (2s) electron, and (2) development of a ray tracing code for an amplifying medium of varying (e.g., collimating) lateral density profile. Results using this code are shown for concave lateral density profiles.     

角量控制的激光天线设计

在多环检测系统理论的基础[4,5]上,通过对激光天线单镜和双反射镜的高斯光束的传播规律和双镜距控制光斑稳定不变的实验数据[1,2],来进行激光天线的设计。设计采用了高斯光束控制入射光束的光腰位置,对天线副镜和主镜的入射角、反射角和天线发散角的控制方法,设计了天线的副镜和主镜的曲率半径、焦距和直径,达到了光斑保持的目的。计算公式简单,使用方便,计算公式和实验测定的数据误差在工程设计要求的范围以内,适合工程设计的需要。     

激光散斑测速和粒子像测速技术中的频谱模板方法

文中提出了用流场的一次曝光像的强度谱作为模板提取杨氏条纹，以获取尖锐的自相关分布的方法，并给出了该方法用于激光散斑测速和粒子像测速技术的计算机模拟结果以及粒子像测速的应用例子。     

Effect of pattern shape on etching wall profile in slider fabrication

The effect of pattern shape on etching wall profile in slider fabrication is studied. The testing results show: (1) the wall profile of round pattern is steeper than that of long rectangular; (2) for round patterns, the smaller the radius is, the steeper the wall profile is; (3) the profile of outer angle is steeper than that of inner angle. The flying height offset caused by wall profile with different shapes can be 8% of total flying height, so it is necessary to consider the effect of pattern shape on etching wall profile in ABS design, especially for ultra low flying height slider.