在本論文中，為了探討不同波長之激發光搭配YAG 螢光粉封裝成白光LED 的光學特性，因此建立了不同激發光YAG 螢光粉光學模型，而我們利用蒙地卡羅 (Monte-Carlo) 光追跡法結合米氏散射(Mie Scatter) 原理來模擬光線在YAG 螢光粉內的散射行為，並藉由二次光追跡來得到吸收係數和轉換效率。由於藍光經過YAG螢光粉後會發生形變，所以引入β參數結合螢光粉吸收頻譜來修正藍光頻譜形變的情形，並利用線性疊加的方式還原其頻譜，最後藉由實際半球封裝白光LED來驗證光學模型的準確性。In order to explore the property of white light LED, we build the phosphor model which is encapsulated with different LED wavelength. we use the Monte-Carlo ray tracing method with Mie scattering theory to simulate the scattering behavior in YAG phosphor, and obtain absorption coefficient and transfer efficiency by 2-nd ray tracing. Because the spectrum of blue light will distort by YAG phosphor, we introduced a coefficient β to compensate the distortion of blue light spectrum, and recover the original spectrum by superposition. At last, we verified the accuracy of model by experiment.
