這環保意識抬頭的時代，各國產業與學界先進為了健康照明及節約能源，把太陽光導入室內，把太陽光當成照明系統，稱為自然光照明系統，而自然光照明系統又分為集光、傳光、放光等三個子系統，但當能量從集光系統到傳光系統時容易造成大量損耗，因此需要一個有效光學耦合器，以降低光能量在系統轉換時的損失。本文的入射光源是使用導光磚在不同的時間點有不同角度的光源，此耦合器能把離散光源都能收斂進導光管，以達到各個角度的光線都能有準直此透鏡的設計方法是運用自由曲面，此種方法能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效率。最後以照明光學軟體進行模擬與分析， 光耦合平均效率提升約30%，光傳輸平均效率提升約40%。

The Natural Light Guiding System(NLIS) developed at NTUST is designed to guild the outdoor sunshine for indoors illumination. The system can be divided into three subsystems: the light collecting sub-system(LCS), the light transmitting sub-system(LTS), and the light emitting sub-system(LES). These three sub-systems are intimately connected with one another. However, a great deal of energy is wasted during the process of passing the sunlight from the LCS to the LTS. In this research,
we design an optical coupler based on “Free-form” structure to improve the efficiency. According to the simulations and analysis of this “coupler surface” by the optical simulation software, the results showed that the efficiency of the transmission was improved more than three times comparing to the original system.

1. Whang AJW, Chen YY, Wu BY, Innovative design of Cassegrain solar concentrator system for indoor illumination utilizing chromatic aberration to filter out ultraviolet and infrared in sunlight, Solar Energy, in press, (2009)
2. Whang AJW, Wang CC, Chen Y Y, Design of cascadable optical unit to compress light for light transmission used for indoor illumination," Renewable Energy, 34(10), 2280-2295 (2009)
3. Callow J, Daylighting using tubular light guide systems, PhD Thesis, University of Nottingham, (2003)
4. A. Rosemann, M. Mossman, L. Whitehead, “ Development of a cost-effective solar illumination system to bring natural light into the building core, ” Solar Energy, Vol. 82, pp. 302-310 (2008)
5. Kischkoweit-Lopin, M., “ An overview of daylighting systems, ” Solar Energy, Vol. 73, No. 2, pp. 77-82 (2002)
6. Jean, L.S., Gilles, C., “ Anidolicdaylighting systems, ” Solar Energy, Vol. 73, No. 2, pp. 123-135 (2002)
7. Himawari Solar Lighting System La Foret Engineering Co., Ltd. : http://www.jato-it.com/himawari/technology_1.php
8. W.J.Smith, E.Betensky, and D.Williamson, et a1, “The Past, Present, and Future of Optical Design”，SPIE-OSA 6342，1-32 (2006)
9. Oliver Dross,Ruben Mohedanoa, “Review of SMS Design Methods and Real World Applications”,Proc. of SPIE Vol. 5529 ,35-47(2004).
10. P. Benitez, J. C. Minano, J. Blen, R. Mohedano, J. Chaves, O.Dross, M. Hernandez, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions”,Opt. Eng.43, 1489–1502 (2004).
11. Lin Wang, Keyuan Qian, and Yi Luo, “Discontinuous free-form lens design for prescribed irradiance”, APPLIED OPTICS . Vol. 46, No. 18(2007)
12. Harald Ries, and Julius Muschaweck, “Tailoring freeform lenses for illumination”Proceedings of SPIE Vol. 4442 (2001)
13. H. Ries, “Tailored freeform optical surfaces” J. Opt. Soc. Am. A，Vol. 19, No. 3, 590–595 (2002).
14. 郝翔，「基于自由曲面的LED照明系統研究」，碩士論文，浙江大學信息科學與工程學院(2008)
15. 易勇，「汽車自由曲面前照燈設計及照明效果模擬」，碩士論文，江蘇大學(2004).
16. HenrikWann Jensen, “Monte Carlo Ray Tracing”，Siggraph 2003 Course 44(2003).
17. R. Winston, J. C. Minano, and P. Benitez, “Nonimaging Optics” (Elsevier Academic, (2005).
18. 陳怡永，「使用自然光源以及人造光源之照明導光系統之設計、分析與製造」，博士論文，國立臺灣科技大學電子工程系，指導教授: 黃忠偉，台北(2008).
19. 楊淑樺，「藉由數學分析提升靜態式稜鏡集光器效率」，碩士論文，國立臺灣科技大學電子工程系，指導教授: 黃忠偉，台北(2008).
20. 陳偉安，「具光學結構設計之高效率傳光管」，碩士論文，國立台灣科技大學光電工程研究所，指導教授: 黃忠偉，台北(2012).
21. 徐鈺翔，「新式自由曲面反射罩設計應用於照明光學耦合器」，碩士論文，國立台灣科技大學光電工程研究所，指導教授: 黃忠偉，台北(2012).