LED背景光源反射棱镜的设计

全站仪反射棱镜在暗环境中测量会影响照准精度,为了实现全站仪反射棱镜能够在暗环境中正常使用,对全站仪反射棱镜进行了改进．在反射棱镜中引入LED发光二极管作为背景光源的装置,并通过实验验证了这种装置的可行性．首先,介绍了反射棱镜的结构构造以及工作原理;然后说明了LED发光二极管的优势及改进装置电路的设计;最后,通过实验验证了这种改进装置应用的可行性,实验选择从温度、距离两方面检验该装置对测量工作是否产生影响．2次不同室温温度测试结果证明了该装置产生的温度不会对测量产生影响;距离测试结果证明该装置不会对距离测量产生影响．由以上实验结论证明了这种改进装置的可行性．     

Efficient numerical method of freeform lens design for arbitrary irradiance shaping

A computational method to design a lens with a flat entrance surface and a freeform exit surface that can transform a collimated, generally non-uniform input beam into a beam with a desired irradiance distribution of arbitrary shape is presented. The methodology is based on non-linear elliptic partial differential equations, known as Monge-Ampère PDEs. This paper describes an original numerical algorithm to solve this problem by applying the Gauss-Seidel method with simplified boundary conditions. A joint MATLAB-ZEMAX environment is used to implement and verify the method. To prove the efficiency of the proposed approach, an exemplary study where the designed lens is faced with the challenging illumination task is shown. An analysis of solution stability, iteration-to-iteration ray mapping evolution (attached in video format), depth of focus and non-zero étendue efficiency is performed.     

白光LED用单一基质白光荧光粉的研究进展

白光LED以其独特优势被称为第四代光源,具有广阔的应用前景。单一基质白光荧光粉(SMWP)因颜色稳定、色彩还原性好,成为白光LED用光转换材料的研究热点。概述了由近紫外LED芯片激发的白光荧光粉的研究现状,指出了该荧光粉存在的问题并对其发展趋势做了展望。     

可见光通信中LED非线性补偿和带宽拓展技术

可见光通信(VLC)是一项有前景的技术,作为现有无线通信网络的有益补充,可提供高速率、低延迟及多设备接入等通信服务。借助传统无线通信的高性能编码调制技术,已经设计并实现了各种适配于VLC系统的物理层通信技术。不同于传统射频通信,VLC采用LED作为信号的发射源,LED的调制容易产生非线性失真且调制带宽有限,已成为VLC高速通信的技术瓶颈。针对这两方面的挑战,本文以白光LED为出发点,阐述了白光LED能有效兼顾照明和通信的特性,总结和分类了非线性失真补偿和拓展调制带宽的多种技术,最后本文提出了LED封装材料及工艺、新型Micro-LED器件研究、光源布局设计、码间干扰消除技术等开放性研究问题,以期提高可见光通信系统的性能。     

LED照明的杂散光分析与散热研究

针对LED照明杂散光的形成原因和处理方法,以及LED照明系统散热问题的产生和结温对灯具寿命和发光率的影响,完善LED照明灯具的设计,利用照明灯具的特点,以目前LED照明灯具采用的散热方式和杂散光的处理形式为基准,采用对比测试的方法对灯具样品进行检验测试。通过对检测结果的分析,解决了LED照明的散热设计中涉及到的关键问题。     

Effect of fabrication process on characteristics of phosphorescence organic light emitting diodes with methoxy-substituted starburst low-molecule as a host

The effect of dry process and wet process on the characteristics of phosphorescence organic light-emitting devices (OLEDs) employing a phosphorescent dye fac-tris(2-phenylpyridine) iridium(III) (Ir(ppy)₃) doped into a methoxy-substituted starburst low-molecule material methoxy-substituted 1,3,5-tris[4-(diphenylamino) phenyl]benzene (TDAPB) are investigated. The FT-IR and absorption spectra of TDAPB films fabricated by a dry process, and a wet process are almost same, and the PL spectra of those films are different. The carrier transport capability of TDAPB by a dry process is lower than that by a wet process. The photoluminescence intensity of Ir(ppy)₃ doped in TDAPB fabricated by a wet process is higher than that by a dry process. A maximum external current efficiency of more than 20 cd/A and luminance of more than 10,000 cd/m² were obtained. Maximum luminance of devices monotonously decreases with increasing the thickness of a dry-processed emitting layer. The main emission zone of the OLED was located in almost at the center of the emitting layer. The improvement of device performance in the OLED fabricated by a wet process was achieved due to the high efficient energy transfer from TDAPB to Ir(ppy)₃, high carrier transporting capability and the formation of homogeneous film, compared with that fabricated by a dry process.     

Properties of 2,6-di-tert.-butyl-4-(2,5-diphenyl-3,4-dihydro-2H-pyrazol-3-yl)-phenol as hole-transport material for life extension of organic light emitting diodes

We studied structural and optical properties of 5′ replaced pyrazoline by hindered phenol 2,6-di-tert.-butyl-4-(2,5-diphenyl-3,4-dihydro-2H-pyrazol-3-yl)-phenol (HPhP) films for application in organic light-emitting diode (OLED) as a hole transport layer (HTL). Analysis of impedance and current-voltage characteristics of ITO/HPhP/Al structure has shown that the current is limited by a space charged region with exponential distribution of traps near Fermi level. Characteristics of electroluminescence structure ITO/HPhP/Alq₃/poly(ethylene glycol) dimethyl ether/Al was studied and analyzed. We performed the comparative analysis of luminescence time decay in two types of electroluminescent devices with HTL from pyrazolines derivative with hindered phenol and without it. We showed that hindered phenol in HTL slows down the degradation processes in OLED.     

便于真空脱泡的高折光率LED封装用硅橡胶的研制

在加成型LED封装材料硫化过程中,需要经真空脱泡.在用甲基苯基环硅氧烷(DMenPh)与四甲基环四硅氧烷DH4开环共聚合,乙烯基双封头作封端剂,制备乙烯基硅油过程中,向原料中添加适量三氟丙基环三硅氧烷,实现了向聚合物分子链中引入三氟丙基硅氧链节,降低了聚合物的表面张力,达到便于真空脱泡的目的.     

Light weight design with light metal castings

The article gives a number of examples of light weight design with aluminium and magnesium castings. The high perfection of the high-pressure die casting HPDC technology and new design opportunities for net shape or near net shape components will be presented. New applications of particle reinforced light metals offer additional potential for weight saving and better technical, economical and environmental performance.     

极紫外投影光刻两镜微缩投影系统的光学设计

极紫外投影光刻（EUVL）两镜微缩投影物镜通常采用Schwarzschild结构和平场结构。本文分析了这两种结构在EUVL不同发展阶段的设计特点，并依据有限距反射系统像差理论，从解析解出发，设计了两套平场两镜系统，分别用于对分辨力为70nm、无遮拦、环形视场扫描曝光系统及目前研制的EUVL 32nm技术节点小视场曝光系统的研究。系统设计指标满足极紫外投影光刻要求。     

Optical characteristics of organic light emitting diode with IrQ(ppy)2-5Cl and its emitter

The synthesis and photophysical study of a cyclometalated mixed-ligand iridium(III) complex are reported. The iridium complex (called IrQ(ppy)₂-5Cl) has two cyclometalated 2-phenylpyridine (ppy) ligands and one 8-hydroxyquinoline (Q) ligand, where one of the H atom is substituted by Cl atom. Absorption and photoluminescence spectra are studied for the neat film and films of IrQ(ppy)₂-5Cl doped in 4,4′-N,N′-dicarbazole-biphenyl and polystyrene, together with the electroluminescence spectra using multi-layer light emitting devices. The electronic states are studied using density functional theory calculations. Emission bands are observed at 502 and 666 nm, which arise from ppy and Q ligands, respectively.     

合同能源管理在LED路灯推广中的风险分析

根据合同能源管理在LED路灯推广中的应用情况,建立了一套合同能源管理项目风险评估体系,并提出用层次分析法等数学方法对项目进行风险分析,确定各风险因素的风险系数。以东莞地区的实例,验证了此方法的有效性。     

Hierarchical-genetic-algorithm-based design of a large scale Fresnel lens for a reading light system with multiple LED sources

A conventional Fresnel lens is suitable to be used in the reading light system due to its features of directing and collecting light rays, as well as its properties of being essentially flat, plastic, lightweight, and cost efficient. However, it is not suitable for a reading light system with multiple light sources. To a reading light system with multiple light sources, a Fresnel lens with suitably designed groove angles can be used to improve the performance of that system in both illuminance and uniformity. Nevertheless, suitable groove angles are rather difficult to find if a Fresnel lens consists of a lot of groove angles and each angle covers a wide range of degrees. We develop a hierarchical genetic algorithm (HGA) to search for a set of optimal groove angles to design a Fresnel lens for a reading light system with multiple light sources from an enormous searching space. In addition, the groove angles of the Fresnel lens are directly derived from a conventional Fresnel lens database. The design goal is to maximize the illuminance and simultaneously maintain the uniformity of light rays incident to a specified reading surface. As a result, we can demonstrate that a HGA really works better than a genetic algorithm and the optimally designed Fresnel lens, indeed, offers a better light-guiding performance than a conventional Fresnel lens for a multiple-LED reading light system.     

Applicability of published data for fatigue‐limited design

The use of published fatigue data provides an expedient basis for fatigue‐limited engineering design by alleviating the necessity of explicit testing. However, published fatigue data often exhibits incomplete documentation of the associated test conditions. Incomplete documentation introduces uncertainties in fatigue life prediction that may limit the applicability of the published fatigue data for design applications. Characterization of the applicability of published fatigue data is critical for robust fatigue‐limited design. However, no quantitative methods have been identified which respond to this requirement. A novel method has been developed to provide a systematic characterization of the applicability of published fatigue data based on internationally recognized standards. This method provides a conceptual mechanism to:

• identify the applicability of published fatigue test data for specific design scenarios—thereby informing engineers of potential limitations of published data and allowing prioritization of multiple data sources;
• identify material domains of insufficient applicability—thereby providing a robust basis for identifying beneficial fatigue test programs;
• compromise between design complexity and the uncertainties inherent in fatigue life prediction;
• define a framework for the appropriate documentation of published fatigue data.

A sample of published fatigue data sources associated with a specific fatigue‐limited safety–critical design scenario was assessed by the method presented in this paper. For the majority of the sampled references, the associated documentation was insufficient to allow the fatigue test data to be confidently applied to the subsequent design activity. Copyright © 2009 John Wiley & Sons, Ltd.     

表面贴附微透镜阵列的OLED诱导荧光检测系统

为进一步减小光源的体积、简化光路系统结构,消除毛细管电泳芯片诱导荧光检测系统中激发光源的反射光和杂散光的干扰,设计并建立了垂直层叠结构的有机发光二极管诱导荧光检测系统。针对有机发光二极管器件发光强度较低的问题,采用在器件的玻璃基底表面贴附微透镜阵列薄膜的方法,提高了入射光的强度。在对CCD积分时间、PDMS微透镜直径及两偏振片间的偏振角度等参数进行优化之后,利用检测系统实现了罗丹明B样品溶液的毛细管电泳分离。     

Accelerated light protection performance measurement technology validated for dairy milk packaging design

We report an accelerated measurement technology for prediction of light protection performance of milk packaging by quantifying the ability of a package to preserve a light‐sensitive nutrient present in milk. This measurement technology consists of a light exposure instrument and a detection approach to track changes to the light‐sensitive nutrient, riboflavin (RF), in a light‐exposed solution sample. The light exposure instrument provided an intense, controlled light exposure and a consistent sample environment for an aqueous RF marker solution. Coupled with the light exposure instrument, two alternative detection approaches were used to determine the RF concentration of light‐exposed marker solutions: an accelerated ex situ (AES) approach by high‐performance liquid chromatography or an accelerated in situ (AIS) approach by ultraviolet–visible spectrometry. The capability of each RF determination method was confirmed using measurement systems analysis, and their statistical equivalency was demonstrated. To explore application of the measurement technology for use in package design, a set of high‐density polyethylene packages incorporating surface‐treated TiO₂ pigments was evaluated for light protection performance by AES and AIS. For the same package set, experiments monitoring RF degradation in extended‐shelf‐life milk products under retail dairy storage conditions showed strong correlation with the AIS method (R² > 0.97). Riboflavin retention increased under both retail and accelerated light exposure conditions for package designs containing greater loadings of surface‐treated TiO₂ confirming its light protection efficacy. This research illustrates the utility of the accelerated methods to quantitatively evaluate package designs for light protection performance for nutrient preservation.     

Use of surface plasmon-coupled emission for enhancing light transmission through Top-Emitting Organic Light Emitting Diodes

In this paper, we perform surface plasmon-coupled emission studies on Rhodamine 6G molecules embedded in a corrugated structure of a thin film composed of fluorinated silica particles, and a binding medium. Our results show enhancements of photoluminescence due to surface corrugation. By varying the size of the fluorinated silica nanoparticles we were able to control the surface correlation length scale of the corrugated surface structure. It was found that the coupling efficiency of the directional light emission is strongly correlated to the surface morphology, particularly the surface correlation length, of the corrugated dielectric structure. This substantial enhancement of signal could potentially be utilized in Organic Light Emitting Diode devices to enhance the light emission and transmission through a thin silver layer which can also serve as the cathode in Top-Emitting Organic Light Emitting Diodes.     

Nanowire encapsulation with polymer for electrical isolation and enhanced optical properties

Light management and electrical isolation are essential for the majority of optoelectronic nanowire (NW) devices.Here,we present a cost-effective technique,based on vapor-phase deposition of parylene-C and subsequent annealing,that provides conformal encapsulation,anti-reflective coating,improved optical properties,and electrical insulation for GaAs nanowires.The process presented allows facile encapsulation and insulation that is suitable for any nanowire structure.In particular,the parylene-C encapsulation functions as an efficient antireflection coating for the nanowires,with reflectivity down to ＜1％ in the visible spectrum.Furthermore,the parylene-C coating increases photoluminescence intensity,suggesting improved light guiding to the NWs.Finally,based on this process,a NW LED was fabricated,which showed good diode performance and a clear electroluminescence signal.We believe the process can expand the fabrication possibilities and improve the performance of optoelectronic nanowire devices.     

A Jones matrix formalism for simulating three-dimensional polarized light imaging of brain tissue

The neuroimaging technique three-dimensional polarized light imaging (3D-PLI) provides a high-resolution reconstruction of nerve fibres in human post-mortem brains. The orientations of the fibres are derived from birefringence measurements of histological brain sections assuming that the nerve fibres—consisting of an axon and a surrounding myelin sheath—are uniaxial birefringent and that the measured optic axis is oriented in the direction of the nerve fibres (macroscopic model). Although experimental studies support this assumption, the molecular structure of the myelin sheath suggests that the birefringence of a nerve fibre can be described more precisely by multiple optic axes oriented radially around the fibre axis (microscopic model). In this paper, we compare the use of the macroscopic and the microscopic model for simulating 3D-PLI by means of the Jones matrix formalism. The simulations show that the macroscopic model ensures a reliable estimation of the fibre orientations as long as the polarimeter does not resolve structures smaller than the diameter of single fibres. In the case of fibre bundles, polarimeters with even higher resolutions can be used without losing reliability. When taking the myelin density into account, the derived fibre orientations are considerably improved.