基于白光LED的光谱共焦位移传感器

为实现光谱共焦位移传感器的小型化、低功耗和高精度,在设计过程中选择体积小、耗电量小的白光LED作为传感器的光源,并使用光纤耦合器代替复杂的分光棱镜式光学系统结构。色散镜头采用消色差透镜与非球面透镜组合的方式,在使用较少透镜数量的情况下达到较好的像差校正能力。同时结合光强归一化等数据处理方法,消除白光LED光源光谱光强分布不均匀等因素对测量精度造成的影响,得到准确、稳定的峰值波长与位置间的对应关系。通过双频激光干涉仪对系统进行标定和测量,实验结果表明使用435~655 nm波段,系统测量范围可以达1.7 mm,平均测量精度1.8μm,满足一定的测量需求。     

高光谱分辨率近红外CO2成像光谱仪设计与模拟

为满足大气CO2吸收光谱测量的要求,基于成像光谱仪基本工作原理和光学设计理论,设计了一种近红外CO2吸收光谱高光谱分辨率成像光谱仪.它采用简单平面反射光栅光谱仪结构,由入缝、两片聚焦透镜、平面反射光栅及两片成像透镜组成.透镜材料为普通常用光学玻璃,为减化系统结构透镜采用了二次非球面设计.采用ZEMAX软件对近红外光谱仪的光学系统进行了优化设计与模拟分析.最终设计与模拟分析结果表明,该光学系统光谱范围为1 591～1 621 nm,分辨率＜0.08 nm,F数为1.8,满足设计要求.     

LED光照度叠加特性分析

计算LED光源对视场内的照射强度是设计均匀性光源的基础,也是视觉检测系统获得高质量图像的关键要素之一.本文以实验结果分析为依据,研究LED光的照度叠加特性.建立了单个LED光照模型,给出了单个LED照射条件下视场内任一点的照度计算方法;基于建立的单个LED光照模型,研究出两同色LED光的叠加特性,并给出了两同色LED光照射时视场内任一点的照度计算方法;为验证该方法的有效性,对3个LED光进行叠加实验,并在视场内任意选取20个点.实验结果显示:1根据本文所提方法求得的灰度值与真实值间的总体偏差为1.085,说明两者一致性良好;2 3个LED光照度叠加可看成其中两个LED组合成一个LED,再与另一个LED进行照度叠加;同理,n个LED光照度叠加可看作是由单个LED两两叠加后,再进行重复的叠加计算.     

波长校正调节螺杆调节的原理和方法

721型分光光度计采用自准式光路,单光束方法,其波长范围自360～800ｎｍ,用钨丝白炽灯泡作光源,其光学系统分光部分如图1。图1　光学系统分光部分图1.光源灯　2.聚光透镜　3.色散棱镜　4.准直镜　5.狭缝　　6.反射镜由光源灯发出的连续辐射光线,射到聚光透镜上,会聚后再经过平面转角90°,反射至入射狭缝,由此入射到单色器内,狭缝正好位于球面准直镜的焦面上,当入射光线经过准直镜反射后就以一束平行光射向棱镜(该棱镜的背面镀铝),光线进入棱镜后,就在其中色散,入射角为最小偏向角,入射光在铝面上反射后是依原路稍偏转一个角度反射回来,这样从…     

高效非成像聚光光学系统设计与性能分析

针对菲涅尔透镜存在实际光学效率偏低的问题,本文设计了一种由非球面透镜和棒锥镜组成的高效非成像聚光光学系统。在光学设计软件Zemax的序列模式下对非球面透镜进行了优化设计,通过最大程度地减小球差,像面光斑的几何半径从42 mm降到了1.7 mm。基于此,在Zemax的非序列模式下,完成了非球面透镜和棒锥镜的建模和优化,通过蒙特卡罗光线追迹分析实现了光学效率为87%、接收角为0.9°的非成像聚光光学系统。最后,基于非球面透镜阵列和棒锥镜样品,实现了高倍聚光型光伏模组的封装与测试。测试结果表明,该模组的光电转换效率达30.03%,与菲涅尔透镜构成的高倍聚光型光伏模组相比有显著提升。     

光固化快速成形中的紫外LED光源系统实验研究

面向我国各类院校和中小企业教育、研发需求,本文提出采用紫外LED光源替代光固化快速成形设备中紫外激光器及汞灯等传统光源,设计了一个基于单片紫外LED的光源系统,对光敏树脂进行固化.该光源系统采用基于多透镜结构的聚焦系统对单片LED聚焦;同时,对LED芯片进行闭环控制以保证其工作在恒稳状态.实验结果表明,该光源系统各项指标达到设计要求,系统运行稳定、结构简单,具有可操作性.与光固化成形设备中的其它光源系统相比,在保证一定的制件精度和速度的基础上,具有低造价和低运行成本等突出特点,有较高的性能价格比.     

设计如何使生活变得更“低碳”——论led光源的设计

本文从LED光源应用于道路照明实际要求出发,对LED路灯的光学系统和灯具的配光要点进行分析,设计出了一种混合型反射罩光学结构,从而说明专业设计将使生活变得更“低碳”。     

自由曲面LED配光设计

自由曲面灵活的空间布局和设计自由度,能够简化光学系统的结构,提高照明效果。本文介绍了自由曲面的应用以及发展现状、构造光学自由曲面的原理,并给出了求解自由曲面面型、光学追迹模拟与结果分析的实例,发现对LED光源的自由曲面透镜设计中,需要对目标面照度进行一定的过校正。     

基于遗传算法的倾斜式光接收机设计

光接收机作为室内可见光通信系统的重要组成部分,其接收角度的不同将会影响系统的性能。传统可见光通信系统采用的是垂直光接收机,其室内角落的信噪比(SNR)较低,信噪比峰-谷值较大。为了降低SNR峰-谷值,提高SNR在室内分布的均匀性,本文提出并设计了基于遗传算法的倾斜式光接收机。数值分析结果表明,采用倾斜式接收机的可见光通信系统,SNR的分布更加均匀。在12 W单个LED光源的系统中,SNR的峰-谷值改善了4.98 d B。在总功率为12 W的四个LED光源的系统中,SNR的峰-谷值改善了2.51 d B。由此可见,在可见光通信系统中,采用倾斜式光接收机可以改善系统的性能。     

椭圆柱透镜组准直半导体激光束的优化设计

采用光线矢量法设计了两个相互垂直的椭圆截面柱透镜组来准直半导体激光束。利用多目标优化中的加权和法进行优化计算,并提出自适应加权系数优化法。此方法能根据计算结果自动调整加权系数,从而达到最佳的优化结果。计算结果表明,该准直系统可达到45μrad左右的发散角,远远优于其它截面柱透镜组（毫弧度数量级）的准直效果。同时两柱透镜间距取适当值,还可在远场形成圆形光宽。     

基于Android的智能可调光LED灯节能控制

针对家庭LED灯能源耗电问题,提出了一种智能调光节能控制方法。该方法以安卓操作系统为平台,智能手机作为客户端,利用LM3409HV降压自适应反馈控制机制,通过Wi Fi网络实现无线远程可调光节能LED灯的低功率照明。该系统采用太阳能绿色可再生能源为智能电网供电,结合室外光强,通过光敏传感器和脉宽调制(PWM)技术调节LED灯亮度。在通用输入电压下,可实现高效率、高功率因数调光。与传统的机械式开关LED照明电灯相比,智能调光系统设计的软硬件更为灵活和方便、成本更低、功耗更小,界面和功能都具有良好的通用性、准确性,具有广泛的应用前景。     

Improvement of brightness with Al2O3 passivation layers on the surface of InGaN/GaN-based light-emitting diode chips

In this study, sputtered 50, 70 and 90 nm thick Al₂O₃ thin films were evaluated as a passivation layer in the process of InGaN-based blue as LEDs (Light-Emitting Diodes) in order to improve the brightness of LED lamps. For packaged LED lamps, lamps with Al₂O₃ passivation layer had higher brightness than ones with SiO₂ passivation layer, and LED lamps with 90-nm Al₂O₃ passivation layer were the brightest among four kinds of lamps. Although lamps with Al₂O₃ passivation layer had a bias voltage 0.25 V at 20 mA forward current higher the lamps built with SiO₂ passivation layer, their brightness was improved about 13.6% higher than the conventional LEDs with no change in emitting wavelength.     

LED灯具光通量的计算方法

LED灯具光通量的计算方法是为了解决LED灯具生产前LED灯芯选用问题。LED灯具生产,LED灯芯的选用是至关重要的,它直接影响LED灯具的产品质量及生产效率。     

Temperature Measurement Technique for Stabilizing the Light Output of RGB LED Lamps

The efficiency of light-emitting-diode (LED) lights approaches that of fluorescent lamps. LED light sources find more applications than conventional light bulbs due to their compactness, lower heat dissipation, and real-time color-changing capability. Stabilizing the colors of red–green–blue (RGB) LED lights is a challenging task, which includes color light intensity control using switching-mode power converters, color point maintenance against LED junction temperature change, and limiting LED device temperature to prolong the LED lifetime. In this paper, we present a LED junction temperature measurement technique for a pulsewidth modulation diode forward current controlled RGB LED lighting system. The technique has been automated and can effectively stabilize the color without the need for using expensive feedback systems that involve light sensors. Performance in terms of chromaticity and luminance stability for a temperature-compensated RGB LED system will be presented.      

道路照明用LED灯具标准对比及趋势分析

LED照明产品的广泛应用和技术的迅猛发展,给LED照明产业标准化研究带来了新的机遇与挑战。本文从技术要求(包括:光通量维持率及寿命、初始光效、显色性)和测试方法(光衰测试方法)的角度对2008～2010年间我国发布的一些代表性国家、行业和地方道路照明用LED灯具标准进行了对比分析,得出如下结论:1)我国各地道路照明用LED灯具标准存在显著差异,急需统一的道路照明用LED灯具标准来有效规范整个行业的发展;2)LED照明技术的不断革新和进步推动着LED照明相关标准的不断更新和改进,已经有并即将有更多符合产业发展要求的标准被逐步推出。可以预见的是,道路照明用LED灯具标准将朝着统一规范化、细致化、全面化的方向发展。鉴于我国道路照明用LED灯具市场的特殊情况,该项标准的制定甚至可能优先于国际标准。     

Temperature estimation of high-power light emitting diode street lamp by a multi-chip analytical solution

Light emitting diodes (LEDs) are now widely used in many fields including traffic lights, vehicle backlights and liquid crystal display (LCD) displays because of their long life, good illumination efficiency and low energy consumption. At present, LEDs are increasingly replacing the traditional lighting and are being used in general illumination such as the street lamp. For the high-power LED street lamps, good light extraction is the most important thing, but low junction temperature of the LED modules is also critical for achieving a long lifetime and a high optical efficiency. Actually, there have been many reports about early failures of street lamps, called dead lamps that have been regarded as a barrier in the public and administration acceptance of LED street lamps. Therefore temperature estimation is always a crucial issue for LED product development. A multi-chip spreading thermal resistance model was applied to estimate the temperature distribution of LED street lamp. The experiment was first done to obtain temperatures of several locations in a prototype LED street lamp. Then the multi-chip spreading resistance model was established to calculate the full temperature distribution. Comparison between the model calculation and experimental measurement showed a good agreement, which demonstrates that the present model can be used in engineering design to estimate the temperature distribution of high-power LED street lamps.     

Bivariate constant stress degradation model: LED lighting system reliability estimation with two‐stage modelling

Light‐emitting diode (LED) lamp has received great attention as a potential replacement for the more commercially available lighting technology, such as incandescence and fluorescence lamps. LED which is the main component of LED lamp has a very long lifetime. This means that no or very few failures are expected during LED lamp testing. Therefore, degradation testing and modelling are needed. Because the complexity of modern lighting system is increasing, it is possible that more than one degradation failures dominate the system reliability. If degradation paths of the system's performance characteristics (PCs) tend to be comonotone there is a likely dependence between the PCs because of the system's common usage history. In this paper, a bivariate constant stress degradation data model is proposed. The model accommodates assumptions of dependency between PCs and allows the use of different marginal degradation distribution functions. Consequently, a better system reliability estimation can be expected from this model than from a model with independent PCs assumption. The proposed model is applied to an actual LED lamps experiment data. Copyright © 2009 John Wiley & Sons, Ltd.     

Luminescence properties of (Ca,Y)-α-SiAlON:Eu phosphors

(Ca,Y)-α-SiAlON:Eu phosphors for white LED lamps were prepared and their luminescence properties were investigated. A red shift of emission wavelength occurred when Ca was partially replaced by Y. Raising the sintering temperature also caused the red shift. As a result, the peak emission wavelength varied from 585 nm to 608 nm, with increasing of the Y content and the sintering temperature, and therefore the chromaticity range of (Ca,Y)-α-SiAlON phosphors extended to longer wavelength by these results. The corresponding correlated color temperature (CCT) of white LED lamps using (Ca,Y)-α-SiAlON:Eu also extended to the temperature as low as 1700 K.     

基于GSM网络的路灯监控系统数据远传仿真

传统的路灯控制与维护手段已不再适应现代化的要求,设计和实现自动化程度高、运行可靠、高效节能的路灯远程监控系统,是当今城市现代化发展的必然要求。论文详细介绍选择GSM网络的短消息业务来实现数据远传;利用Visual Basic编程环境,设计了上位机的监控系统;下位机利用Proteus软件进行仿真;在上位机和下位机之间各加一个无线调制解调器GSM Modem进行数据远传。     

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。