Final_照度与亮度均匀的半导体照明自由光学曲面构建

1、照度与亮度均匀的半导体照明自由曲面光学系统构建 (申请清华大学工学博士学位论文) 培 养 单 位： 电子工程系 学科： 电子科学与技术 研究生： 冯 泽 心 指 导 教 师： 罗 毅教 授二一二年四月 照度与亮度均匀的半导体照明自由曲面光学系统构建冯泽心Freeform surface optical system construction of solid state lighting for uniform illuminance and luminance Dissertation Submitted to Tsinghua University in partial fulfillment of the requirement for the degree of Doctor of philosophy in Electronic Science and Technology by Feng Zexin Dissertation Supervisor: Professor Luo Yi April, 2012 关于学位论文使用授权的说明 本人完全了解清华大学有关保留、使用学位论

2、文的规定，即： 清华大学拥有在著作权法规定范围内学位论文的使用权， 其中包括： （1）已获学位的研究生必须按学校规定提交学位论文，学校可以采用影印、缩印或其他复制手段保存研究生上交的学位论文； （2）为教学和科研目的， 学校可以将公开的学位论文作为资料在图书馆、 资料室等场所供校内师生阅读，或在校园网上供校内师生浏览部分内容； （3）根据中华人民共和国学位条例暂行实施办法 ，向国家图书馆报送可以公开的学位论文。 本人保证遵守上述规定。 （保密的论文在解密后遵守此规定）（保密的论文在解密后遵守此规定） 作者签名： 导师签名： 日 期： 日 期： 摘 要 I摘 要 半导体照明要想进入千家万户，并实现节能，必须具有良好的照度与亮度均匀性。传统封装 LED 的光分布特性不能获得上述优异的照明效果，必须利用自由曲面光学系统对其光分布进行调控。 本论文围绕极窄光束角内照度均匀、目标平面亮度均匀、光源表面发光亮度均匀柔和以及针对理想近似的偏离，对自由曲面光学系统的构建进行了研究。 在实现极窄光束角内的照度均匀分布方面，提出了一种针对点光源近似的双自由曲面构建方法，首先根据能量守恒获得外自由曲面数据点

3、横向坐标与光源发光角度坐标的对应关系，然后，分别基于描点法与等光程原理迭代获得内自由曲面数据点坐标与外自由曲面数据点的纵向坐标。结果表明，基于本方法构建的半径为 10mm 的自由曲面全内反射透镜可实现光半峰值光强角小于 6o且 3o光束角内照度均匀度为 0.72 的效果。 在实现目标平面上亮度均匀分布方面，以最复杂的路面亮度为出发点，将针对路面亮度的自由曲面光学系统构建转化为针对最优化余弦基照度分布的构建。实例表明，与具有等照度分布的传统半导体道路照明光源相比，按上述方法获得的自由曲面光学系统对亮度均匀性尤其是表征斑马纹效应的纵向亮度均匀度具有较大的提升，亮度照度比也较大增加，并且对安装距离及灯具仰角容忍度高，同时保证了较好的照度均匀度。 在将高亮度的 LED 阵列转化为亮度均匀且光出射度低的面光源方面，提出了基于自由曲面微透镜阵列的光扩散板构建方案。结果显示，针对小角度发光草帽型 LED 及贴片型 LED，基于自由曲面微透镜阵列光扩散板的面光源在保证较高的光出射效率的前提下可实现较好的发光亮度分布。 针对偏离理想情况下的自由曲面光学系统构建方面，在前人的基础上，提出了目标至光源的反馈

4、迭代构建方法，基于目标至光源的分离变量方法，通过与目标照度分布及仿真照度分布相关的特殊反馈函数，迭代修正目标区域的照度分布，以补偿由于光源的扩展性及曲面误差带来的与给定照度分布的偏移。应用于均匀照度分布的实例表明，照度均匀度可从 19%提升到 81%，针对复杂的照度分布也可实现较好的效果。 关键词：发光二极管；半导体照明；非成像光学；自由曲面光学系统 Abstract IIAbstract Solid state lighting sources must have good luminance and illuminance uniformity in order to be widely accepted by millions of households and then achieve excellent energy conservation. Since the light distributions of the traditional packaged LEDs can not get the favorable lighting features mentioned

5、above-the luminance and illuminance uniformity, free-form surface optical systems must be adopted to adjust their light distributions. This thesis investigated in the construction of several free-form surface optical systems which can produce high illuminance uniformity within a very narrow beam angle, high luminance uniformity on the target plane, high luminance uniformity and visual softness of the surface light sources on the ideal approximation and in some cases of ideal approximation deviat

6、ions. A dual free form surfaces construction method was proposed for achieving a uniform illuminance distribution within a narrow beam angle on the point source approximation. Firstly, the relationship between the angular coordinates of the source and the transverse coordinates of the secondary surface points were obtained based on the energy conservation. Then, the coordinates of the primary surface points and the longitudinal coordinates of the secondary free-form surface points can be obtaine

7、d iteratively based on the point-by-point method and aplanatic condition. Results show that the free-form surface lens constructed by this method has a semi-high-angle of less than 6o and an illuminance uniformity of 0.72 within the 3o beam angle in far field. In the aspect of forming high luminance uniformity on the target plane e.g. the complex road surface, the construction of a freeform surface optical system for the road surface luminance can be transformed to the construction for an optima

8、l cosine-based illuminance distribution. An example show that, compared with the traditional solid state lighting source, the lighting source with the freeform optical systems designed by this method has a huge improvements in luminance uniformity especially the longitudinal luminance uniformity for zebra effect, a larger luminance/illuminance ratio, better tolerances in Abstract IIImounting spaces and mounting angles whilst guaranteeing a high illuminance uniformity In the aspect of converting

9、the high luminance LED arrays into a surface light source with uniform luminance and low luminous exitance, a diffuser construction solution based on the freeform surface microlens array was proposed. Results show that surface light sources using the microlens array diffusers can produce a good luminance distribution on the premise of a high light output ratio. Based on previous work, a feedback iteration method using target to source strategies was proposed in the construction of freeform optical systems for the case of ideal approximation deviations. In this method, a special feedback function related with the desired and simulated illuminance distributions was used to iteratively modify the illuminance distributions on the target in order to compensate the deviations caused by the extended light source and the freeform surface errors. An example applied for producing a uniform illuminance distribution sh

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