基于蒙特卡罗模拟方法的光源用LED封装光学结构设计

LED's Optical Encapsulation Structure Design Based on Monte Carlo Simulation Method

为满足正在兴起的LED照明光源的设计优化要求 ,必须探索适合LED光学结构设计的有效方法。引进蒙特卡罗 (MonteCarlo)随机模拟方法对常规形式发光二极管 (LED)的光学封装结构进行模拟 ,得出了LED的光强分布 ,并进行实际测量 ,模拟结果与实验所得结果吻合较好 ,证明蒙特卡罗方法是进行LED光源光学结构设计的一种有效工具 ,可以以此作为LED光源的设计优化手段。重点探讨了此方法模拟中的随机数构造、优化 ;LED模型 ;仿真的计算机实现 ,仿真结果的验证 ;结构优化的思路等问题。

The light emitting intensity of light-emitting diode (LED) improved so much in these years that it is (profitable) enough to be used for design LED solid lighting. This LED light have been proved to be having many excellent virtues and was predicted to be having the possibility of leading the lighting industry into a new revolution. So in order to meet the design and optimization requirement of developing LED light, an effective method that is befitting in this work should be found out. In this article, the traditional LED's light distribution is obtained through carrying out simulation of LED's optical encapsulation structure by means of Monte Carlo method but not geometry optics method. The Monte Carlo LED simulation model is abstracted as dot light source, reflecting bowl, interface of epoxy resin and air. Light is treated as photons' physical reactions with every possible part of whole LED's optical encapsulation structure after emitting from the dot light source. These reactions include photons' reflection and refraction on interface, absorption by epoxy resin material or wear down by interface of optical structure. Every stochastically emitted photo follows the physical optics and geometry optics rules and finally gets out of encapsulation and then is collected in a screen. When a large number of photons' travel routes and locations of reaction with screen were determined, the light distribution pattern of correspondent LED's optical encapsulation structure would be presented. And the average illumination intensity can be figured out through statistic method. Here, some kinds of traditional LED's optical encapsulation structure were simulated using Monte Carlo (me thod). And experiments were performed using the correspondent LED's optical encapsulation structure with the same conditions just like what were used in simulation. The Φ5, Φ12 dome-top and Φ5 plane-top LED tubes were (simulated and) experimentally measured for comparison. Some conclusions can be drawn that the simulation results fit the experimentation results well in the light distribution. This testified that Monte Carlo method is one of the effective tools for LED light's optical design. There are some differences between (simulation) and experiment results in the patterns' distribution scale because there are still some conditions' differences just as characteristics of encapsulation materials and shapes of encapsulation structure. It is accurate enough for analyzing and finding out the relations between light distribution and correspondent optical structure and directing the right ways for designing more (effective) LED with new optical structure. The optimization and construction of random figures, the validation of simulation results, the comparison of (different) optical structure and the structure optimization were discussed in this article.