用于LED道路照明的渐变菲涅尔透镜设计

发布时间：2018-10-08 12:49

【摘要】：LED作为一种新兴照明光源,因其在生产过程中不会产生污染,成品绿色环保,功耗远低于传统高压钠灯,且使用寿命长、电光转换效率高,使得越来越多的国家开始关注它在照明领域的发展前景。在照明行业中,传统灯具被LED所取代已成为一个必然趋势。作为城市化建设的一项重要内容,良好的夜间道路照明条件也可以减少犯罪活动出现的概率,并具有美化城市夜景的效果。将LED用于道路照明时,由于其固有的光强度分布曲线无法直接满足道路照明的要求,需要通过二次光学设计来改造原有的光强度分布曲线,形成所需的配光曲线,因此,如何最大化提高灯具的光效率以及选择合适光强度分布形式即LED二次光学设计成为道路照明的重要研究课题。现阶段国内外用于道路照明的LED透镜主要采用自由曲面透镜的结构形式,可分为“花生壳”透镜和TIR(total internal reflection)透镜两种类型。但这两种透镜均存在厚度较大从而导致散热性差的问题,而且这一缺点因传统透镜的结构特点而无法克服。菲涅尔透镜相比于传统透镜最大的优势是厚度薄、重量小、透光率高,但由于其保留了原透镜的曲率半径,因此可基本保持原光路不变。本课题立足于对用于LED道路照明的渐变菲涅尔透镜设计,论文内容主要包括以下方面:1)介绍了LED的优势、分类方法及自由曲面透镜的几种设计方法,明确课题研究内容。研究了《城市道路照明设计标准》(CJJ45-2006)的配光要求。在介绍非成像光学理论的基础上,分析了照明的相关概念、自由曲面光学器件的设计方法和路灯透镜设计流程。2)确定所用LED光源的辐射特性,以及目标照明面的照度要求,根据能量守恒定律将光源和目标照明面进行均匀的网格划分,然后以边缘光线理论以及Snell定理作为理论基础,列出反映自由曲面面型的偏微分方程,使用Matlab计算得到自由曲面的面型数据。3)构建自由曲面透镜模型,将面型数据导入Solidworks中通过曲线放样、曲面缝合以及镜像等步骤,拟合出透镜实体。在研究过程中,提出一种新的快速建模的方法。该方法是在Tracepro中,利用Scheme语言直接快速建模。分析比较了两种建模方法的利弊。4)构建渐变菲涅尔透镜,建模出10个出光效果相同但大小不同的自由曲面透镜,叠加后进行切割,使其外表面呈现出菲涅尔面型,从而减小透镜体积、增加散热性能。通过光学设计软件Lighttools模拟分析结果表明设计的渐变菲涅尔透镜满足道路照明要求,光照均匀性好(照度均匀度达68%),且透镜厚度明显变薄,解决了传统自由曲面路灯透镜散热性能差的问题,提高了LED的透光效率和使用寿命。经过合理排布渐变菲涅尔透镜,进一步提高了光照均匀性(照度均匀度达95%)。
[Abstract]:LED as a new lighting source, because it will not produce pollution in the production process, the finished product is green and environmental protection, the power consumption is far lower than the traditional high-pressure sodium lamp, and the service life is long, the efficiency of electro-optic conversion is high. More and more countries begin to pay attention to its development prospects in the field of lighting. In the lighting industry, the replacement of traditional lamps by LED has become an inevitable trend. As an important part of urbanization construction, good night road lighting can also reduce the probability of criminal activities and beautify the city night scene. When LED is used in road lighting, because its inherent light intensity distribution curve can not directly meet the requirements of road lighting, it is necessary to transform the original light intensity distribution curve through quadratic optical design to form the required light distribution curve. How to maximize the light efficiency of lamps and choose a suitable light intensity distribution form, that is, the secondary optical design of LED, has become an important research topic of road lighting. At present, the LED lens used for road lighting at home and abroad mainly adopts the structural form of free-form curved lens, which can be divided into two types: "peanut shell" lens and TIR (total internal reflection) lens. However, these two kinds of lenses have the problem that the thickness of the two lenses is large, which leads to poor heat dissipation, and this shortcoming can not be overcome because of the structural characteristics of the traditional lenses. Compared with the traditional lens, Fresnel lens has the advantages of thin thickness, small weight and high transmittance, but because it retains the curvature radius of the original lens, it can basically keep the original light path unchanged. This paper is based on the design of the gradual Fresnel lens used for LED road lighting. The main contents of this paper include the following aspects: 1) introduce the advantages of LED, the classification method and several design methods of freeform curved lens, and clarify the research content of the subject. The light distribution requirements of Urban Road Lighting Design Standard (CJJ45-2006) are studied. On the basis of introducing the theory of non-imaging optics, this paper analyzes the related concepts of illumination, the design method of free-form surface optical device and the design flow chart of street lamp lens (.2) to determine the radiation characteristics of the LED light source used and the illumination requirements of the illumination surface of the target. According to the law of conservation of energy, the light source and the illumination surface of the target are divided into uniform meshes. Based on the theory of edge light and Snell's theorem, the partial differential equations reflecting the surface form of free surface are listed. The free-form surface lens model was constructed by Matlab. The surface data were imported into Solidworks to fit the lens entity through the steps of curve lofting, surface suture and mirror image. In the process of research, a new fast modeling method is proposed. This method is in Tracepro, using Scheme language directly and quickly modeling. The advantages and disadvantages of the two modeling methods are analyzed and compared. (4) A gradual Fresnel lens is constructed. Ten free-form surface lenses with the same luminous effect but different size are modeled, and then cut by superposition to make the outer surface of the lens appear Fresnel surface. Thus, the lens volume is reduced and the heat dissipation performance is increased. The simulation results of the optical design software Lighttools show that the designed Fresnel lens meets the road lighting requirements, has good illumination uniformity (the illumination uniformity reaches 68%), and the thickness of the lens is obviously thinned. The problem of heat dissipation of traditional freeform street lamp lens is solved, and the transmission efficiency and service life of LED are improved. The illumination uniformity (illumination uniformity is up to 95%) is further improved by reasonable arrangement of Fresnel lens.
【学位授予单位】：中国科学院研究生院(西安光学精密机械研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM923.34;TU113.666

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