準確模擬預測螢光粉轉換式白光LED的光學特性是固態照明的研究重點之一，之前的研究顯示透過對螢光粉樣品的分析可以建立非常精確的白光LED光學模型，然而照明應用端的光學工程師並不總是能方便取得螢光粉樣本。為了解決這個問題，本論文提出了一個經由對白光LED進行外部光學量測建立模型的方式。在光學模擬部分，本論文提出的簡單白光LED模型中只包含螢光粉粒子半徑與螢光粉粒子濃度兩個關鍵參數；在光學量測部分，本研究首先使用積分球量測LED的光譜，並且使用配光曲線儀量測LED的表面中場光學特性與遠場光學特性。透過調整模型中的參數我們可以使模擬結果在LED表面中場與遠場的所有光學特性與實驗值相當接近，如此就能得到一個簡單白光LED模型。必須注意的是這個模型只是LED在特定功率操作下的等效光學模型，並不是一個完整的通用模型，當LED操作功率改變時，必須再次調整對應參數。這個方法的優點是簡單並且迅速，相對的缺點是此等效模型只能使用在對應的操作功率下。
螢光粉的成本是影響白光LED價格的重要因素之一，在本論文中我們提出了一個簡單的模擬實驗嘗試減少螢光粉在白光LED中的使用量。我們提出的方法是在螢光粉轉換層中加入散射粒子以提高散射效應，提升散射效應可以增加短波長藍光被螢光粉粒子轉換成長波長黃光的機率。在本論文中我們分別固定螢光粉濃度與散射粒子濃度進行模擬，兩組模擬結果都顯示此方法可以有效減少螢光粉的使用量，然而缺點則是系統光學效率的降低，這也代表本方法在未來可以結合LED外部光學元件設計以求達到更好的整體光學表現。
白光LED的空間色彩均勻度也是固態照明的研究重點之一，之前的研究顯示透過外部光學封裝可以達到非常高的空間色彩均勻度，本論文試著使用在螢光粉轉換層中加入散射粒子的方法來達到相同的效果。模擬結果顯示，我們可以經由調整螢光粉粒子濃度與散射粒子濃度在特定目標色溫之下達到良好的空間色彩均勻度，缺點則是系統光學效率有相當程度的降低，這也代表本方法在未來可以結合LED外部光學元件設計以求達到更好的整體光學表現。

One of the important research topics of solid state lighting is to simulate the optical performance of phosphor converted white LED precisely. Previous studies have shown through the analysis of phosphor powder samples can create very precise white LED optical model. However, phosphor powder samples are not always easy to obtain for optical engineers of lighting application area. In order to solve this problem, we proposed a method to model a white LED based on its external optical measurement data. In the optical simulation part, our simple model only contained two key parameters: phosphor particle radius and phosphor particle density. In the optical measurement part, we first measured the optical spectrum via an integrating sphere. Then we measured the surface mid field optical characteristic and far field optical characteristic via a source imaging goniometer. By adjusting the parameters in the model, we could make simulation results of the LED surface mid field and all the far-field optical properties to be very close to the experimental values. Thus we created a simple white LED model. It should be noted that this model is an equivalent optical model under a given operating power but not a complete general model. When the LED operating power is changed, the corresponding parameters must be adjusted again. The advantage of this approach is easily and quickly, the disadvantage of this method is the equivalent optical model is only applicable in a particular operating power.
The amount of phosphor used is a main factor in the price of white LEDs. In this paper, we proposed a simple simulation experiment in trying to reduce the amount of phosphor used in white LEDs. The proposed approach is to add scattering particles into the phosphor conversion layer in order to improve the scattering effect. This would increase the probability that blue light would encounter phosphor particles and be converted to long-wavelength light. We first fixed the concentration of phosphor particles and then fixed the concentration of scattering particles and did the simulation respectively. Both simulation results have shown that this idea can be used to effectively reduce the amount of phosphor powder use. However, the disadvantage is the decrease of optical system efficacy. It also indicates the proposed method can be combined with the design of LED external optical elements to achieve better overall optical performance in the future.
The spatial angular color uniformity of white LEDs is also an important research topic of solid state lighting. Previous studies have shown via an external optical package design could reach very high spatial angular color uniformity. We tried to achieve the same goal by adding scattering particles into the phosphor conversion layer. Simulation results have shown that under a specific target correlated color temperature, we could achieve high spatial angular color uniformity by adjusting the concentration of phosphor and scattering particles. However, the disadvantage is the decrease of optical system efficacy. It also indicates the proposed method can be combined with other optical design concepts to achieve better overall optical performance in the future.

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