LED信号灯二次光学设计

随着科学技术的发展,LED在很多领域中被应用得越来越广泛,如在信号灯中的应用,因此就需要对LED发出的光线进行二次光学设计。文中介绍了一种LED信号灯的二次光学设计思路和方法,通过对光通量的估算,设计出合理的LED分布、光学面罩和菲涅耳透镜。     

一种LED路灯透镜的二次光学设计与研究

LED的二次光学元件设计对LED路灯的配光及光学输出效率至关重要。文章针对大功率LED在路灯上的应用,基于选定的LED进行了一种用于LED路灯的自由曲面二次光学透镜的设计,并采用光学软件进行仿真。结果表明,采用非对称自由曲面二次光学元件可以实现LED路灯的矩形配光,采用这种LED模组组成的路灯便于结构设计、电源安装,不同功率的LED路灯只需要增加不同数量的LED模组即可。此种设计可以在很大程度上提高LED路灯的效率,提高路面照明的均匀度。     

白光LED在电视新闻摄灯的应用设计

随着白光LED的发展,就应用LED光源来设计制作电视新闻摄灯已成为可能。本文讨论了电视新闻摄灯的光学特性、光强分布以及光学设计要求。同时通过与传统的卤钨灯摄灯的比较,分析了电视新闻摄灯在应用LED光源时一些特殊问题。     

基于ASAP软件的LED光学特性模拟

介绍了LED的应用及前景,着重阐述了ASAP软件的使用,并根据LED的发光理论利用该软件对LED进行了光学建模,经过光线追迹后,所建模型的光强分布与实际LED光强分布吻合很好,为二次光学设计打下基础。     

基于分布光度计测试实验的LED二次光学仿真

以LED为研究对象,利用TracePro光学仿真软件和LED分布光度计对其进行光学仿真和光学实验研究,并通过对比验证仿真结果的正确性和仿真方法的可行性。研究结果表明,实验结果和仿真结果吻合,将仿真方法用于LED的光学研究切实可行。利用TracePro对大功率LED的二次光学设计结构进行了仿真,仿真结果表明该LED的二次光学设计结构使LED的光学性能得到了极大的改善,配光效果更理想,光照均匀性更好。     

自由曲面的LED路灯透镜的设计

LED的二次光学元件设计对LED路灯的配光及光学输出效率至关重要.良好的道路照明要求LED路灯的配光为长方形的光型,路灯发出的所有光刚刚可以覆盖住马路,而马路之外的光污染几乎为零.非对称自由曲面二次光学元件的采用可以使LED路灯的长方形配光直接在单个LED模组上完成.整体路灯只需要将这些LED模组阵列按照相同方向简单地排列即可,从而可以简化路灯机构、散热及控制电源的设计.介绍了LED路灯的光学设计,及一种用于LED路灯的自由曲面二次光学透镜的设计方法.     

基于LED大功率扩展光源的二次光学设计

在目前的低碳环境下,LED照明光源逐步替代传统光源,但是由于其本身结构和自身特点,要进行高效的光能利用与照明,必须进行适当的光学设计以便改善光能分布。笔者首先阐述了LED的光学特性及二次光学设计,其次对LED大功率扩展光源的二次光学设计进行了深入探讨。     

基才LED大功率扩展光源的二次光学设计

在目前的低碳环境下，LED照明光源逐步替代传统光源，但是由于其本身结构和自身特点，要进行高效的光能利用与照明，必须进行适当的光学设计以便改善光能分布。笔者首先阐述了LED的光学特性及二次光学设计，其次对LED大功率扩展光源的二次光学设计进行了深入探讨。     

LED路灯的二次光学设计

本文针对大功率LED在路灯上的应用,探讨了LED光源的选择依据,基于选定的LED进行了基于透镜的LED二次光学设计,并采用ASAP软件进行了仿真.结果表明,此种设计可以很大程度上提高LED路灯的效率,提高路面照明的均匀度,达到传统灯具无法比拟的效果.     

InAs/GaAs量子点中间带太阳电池的理论研究与优化

从荧光粉散射机理分析了LED器件色角向分布不均匀的形成原因,提出了一种利用逐点步进光学设计方法,实现了不同入射角度内蓝光光程相等的远荧光粉层结构。应用该方法设计了使用不同折射率载体的LED远荧光粉层光学结构。模拟结果显示,应用所设计的光学形状的远荧光粉层结构,相比传统平面荧光粉层结构,75°方向光斑边缘与中心法线方向色差du′v′从0.05降低到0.01左右,色温偏移降低了43%~98%不等,有效改善了白光LED远程荧光粉封装结构的色度均匀性。该设计不需要增加或改变封装工艺手段,工业生产实现简单,额外成本很少,具有较强的实际应用价值。 更多还原     

风云四号辐射计的高精度动态测角系统

为了测试风云四号气象卫星扫描成像辐射计的扫描镜的动态运动精度，设计了一种高精度动态测角仪。该测角仪利用了扫描成像辐射计的可见光通道，采用622 nm的LED可见光,经过菲涅耳透镜投射到目标板上，然后充满投影光学系统的入瞳,利用光学成像分析像点位置及相互关系的方法来评价扫描镜的运动精度。介绍了该测角仪的投影光学系统、照明系统和系统总体的设计。     

Reliability investigation of light-emitting diodes via low frequency noise characteristics

Investigation of changes of operation and noise characteristics during aging process of light-emitting diodes (LEDs) has been carried out. Several groups of different design (different optics) LEDs based on different materials (nitride-based blue and white LEDs, phosphide-based red LEDs) have been investigated. It is found that leakage current components appear due to LED’s defects and their affect is observed as increase of both the low frequency electrical noise intensity and non-ideality factor of current-leakage characteristic in small current region. No considerable changes of light intensity characteristics during LEDs aging have been observed. Noise modeling, spectral and correlation analysis of optical and electrical fluctuations show on partly correlated optical and electrical fluctuations caused by defects in the active region of the LED. Degradation processes of investigated LEDs foremost occur in the diode chip and lead to the leakage current that has important affect to the electrical fluctuation level, but practically has a weak influence to the light emission properties of LED. Phosphorous layer of white LEDs and additional optical elements have no significant influence to the reliability of investigated LEDs under given aging conditions.     

半导体照明中的非成像光学及其应用

以GaN基功率型发光二极管(LED)为代表的半导体照明光源,具有其他传统光源无法比拟的诸多优点,被公认为21世纪最有价值的新型光源。充分发挥功率型LED的优势,利用非成像光学进行面向实际应用的功率型LED封装光学系统设计,以高端半导体照明光源的制造为突破点,带动整个半导体照明产业的快速进步,已成为半导体照明技术发展的战略选择。回顾了非成像光学的历史、研究进展以及在半导体照明中的应用,并通过设计实例,介绍了面向功率型LED光线耦合、二维给定光分布以及三维给定光分布问题的非成像光学系统设计原理与解决方案。     

非球面镜在光学读取头中的应用

非球面镜的使用能大大简化光学系统,因此被越来越多地应用到各种光学设计中。阐述了非球面镜发展的意义及其在光盘机光学读取头中的应用,并介绍了光学读取头物镜性能的评价和制作材料。     

Computer Modeling and Simulation Evaluation of High Power LED Sources for Secondary Optical Design

Proposed and demonstrated is a novel computer modeling method for high power light emitting diodes（LEDs）. It contains geometrical structure and optical property of high power LED as well as LED dies definition with its spatial and angular distribution. Merits and non-merits of traditional modeling methods when applied to high power LEDs based on secondary optical design are discussed. Two commercial high power LEDs are simulated using the proposed computer modeling method. Correlation coefficient is proposed to compare and analyze the simulation results and manufacturing specifications. The source model is precisely demonstrated by obtaining above 99% in correlation coefficient with different surface incident angle intervals.     

Effect of Different Quantum Well Structures on the Output Power Performance of GaN-Based Light-Emitting Diodes

We investigated the effect of two different quantum well (QW) structures having different indium contents on the optical performance of fully packaged GaN-based light-emitting diodes (LEDs). Dual-spectrum QW LEDs exhibit ～4% higher external quantum efficiency (at 350 mA) than single-spectrum QW LEDs. However, the two types of LEDs exhibit similar efficiency droop behavior. For both types of LEDs, the output power decreases with increasing junction temperature. When the junction temperature exceeds 70°C, the dual-spectrum QW LEDs exhibit lower output power than the single-spectrum QW LEDs. The wavelength dependence of the output power (at 350 mA) of single-spectrum QW LEDs shows that the LEDs with shorter wavelengths experience more rapid optical degradation than the LEDs with longer wavelengths. Based on the wavelength- and junction-temperature-dependent output power, the droop behavior of the dual-spectrum QW LEDs is described and discussed.     

Size effect on optical performance of blue light-emitting diodes

In this paper,size effects on optical performance of blue light-emitting diodes(LEDs)are investigated.The essential physical mechanism is studied by fabricating LEDs with various sizes of the active area and testing optical characteristics.It is found that micro-LEDs have better light extracting efficiency and thermal dissipation compared with broad-area LEDs,which is likely due to the small ratio of perimeter and active area.Furthermore,micro-LEDs are more beneficial for displays due to the stable wavelength under the low pulse width modulation(PWM)current density.     

基于方位角调制的LED道路照明灯具的配光设计研究

提出了一种基于方位角调制的LED道路照明灯具的配光设计方法。选择型号为OSLON SX的大功率LED作为光源,利用16颗LED建立了4×4阵列LED灯具的光学模型。通过改变每一排LED的方位角控制了接收面上的光照度分布。研究表明,当LED阵列上下部分分别倾斜±30°时,接收面的光照度最均匀。     

Temperature-dependent electroluminescence of AlGaN-based UV LEDs

The electrical and optical characteristics of AlGaN-based ultraviolet (UV) light-emitting diodes (LEDs) (265-365 nm) at elevated temperatures (25/spl deg/C-175/spl deg/C) were investigated, and compared to those of InGaN-based visible LEDs (400-465 nm). Strong carrier localization and localized-state emission were retained in the InGaN LEDs up to 175/spl deg/C, leading to temperature-independent emission intensity at low-energy tails. The deep-UV LEDs, however, showed dominant band-edge emission, much smaller alloy broadening, and weaker localization effects. The optical power of the UV LEDs decreased much more rapidly with increasing temperature. The characteristic temperature was in the range of 31-73 K, and decreased with increasing Al content in the active region. These findings implicate the lack of localization effects in AlGaN alloys as one of the causal factors in the poor thermal performance of the UV LEDs and suggest that increasing carrier-confining potentials will provide a critical means to improve their radiative efficiencies.