自然光照明系統R為兼顧環保及健康照明之系統，可直接引導陽光進入室內。此系統可分為三個子系統；集光、傳光及放光。但當光能量從集光系統到傳光系統時容易造成大量損耗，因此需要一個有效的光學耦合器，以降低光能量在系統轉換時的損失。
本文提出一個創新的自由曲面設計方法 “能量權重指標”將此應用於照明光學耦合器，可直接考慮光線向量與能量多寡來進行設計，快速有效評判出對此耦合器最重要的光線，直接進行修正與控制以提升效率。而反射罩外觀的設計是經由空間內心圓方程式推導出反射面的位置與轉動向量，利用此方法配合能量權重建立離散面然後匯聚成反射罩耦合器。
最後以照明光學軟體進行模擬與分析，模擬結果顯示光學耦合器使用前後，光收斂效果平均改善可達2.32倍以上而自然光照明系統R整體傳輸效率也有2倍以上的提升。

A natural light guiding illumination system can be subdivided into three subsystems; the light collector, the light transmitter, and the light emitter. When the sunlight from the collector system passes through the transmitter system, that process may cause serious loss of energy. Therefore an effective optical coupler can reduce energy loss and improve overall efficiency of the natural light guiding illumination system. This paper proposes an innovative freeform design method; the design of The Power Index of Energy. Using this method; the most important light orientations for this coupler can be determined quickly and efficiently. The discrete surface of the reflector coupler’s position and rotation vector can be calculated through the Incenter Equation of Space. In this way, the coupler can directly control and adjust the direction of light so that the overall efficiency of a natural light guiding illumination system can be enhanced. Finally we can use optical simulation software to simulate and analyze the reflector coupler’s efficiency. The results of the simulation show that the average convergence efficiency of an optical coupler can be improved by a factor of more than 2.32, and the average transmission efficiency can be more than doubled.

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