LED照明產業迅速發展且伴隨著發光效率不斷提高之背景下，利用LED體積較小與壽命長之優勢應用於道路上，逐漸取代了傳統燈具，提高於在道路上當照明的可行性。在這個利基下，我們提出自由曲面設計方法以克服LED其特殊光強分佈。

為使能量可以做重新分配，本文提出了一自由曲面設計方法為“以虛擬面分析量建立能量分配”，省略繁雜的計算過程直接在光線與能量上做處理，在光源資訊與預期的照明區域建立關係，同時保有直接在能量上做匹配以及控制光線能力。

我們將此方法應用於矮路燈設計上，矮路燈非一般傳統路燈的高度，而是設定在1.5 m高度上，設計上以幾何光學為基本架構，由圓形光斑轉換成三角光斑，利用點到點至向量推導出多個面的位置與傾斜角度，再利用這些參數建立離散面，多個離散面匯聚成一個自由曲面後匯入光學軟體進行模擬分析與修改，達到中垂線為4 m底邊長8 m之三角型照明區域，平均照度達到17 Lux以上。此燈具的提出可解決一般路燈過高所造成的光源浪費與光汙染問題，同時於偏遠山區資源不足的地方，以矮路燈取代路面照明便於維修與造價較便宜。

As LED lighting efficiency has increased, LED lights for street lighting have shrunk in size and gained lifetime. So, LED lights are gradually replacing ordinary street lights. In this paper, we have proposed a freeform lens design, for use with LEDs deployed as street lights.
The height of our design is 1.5 m, which is different from traditional street light designs. This can reduce light pollution caused by street light positions. Also, the design is easy to maintain and repair, which is very important in rural and mountain areas.
In this paper, we used the optical engineering software, FRED, to simulate a Lambertian source on a mounting normal to the illuminated area. The source was angled up 53.13° from normal to the pole. In order to illuminate a triangle (isosceles) of size 4 × 8 meters, we designed freeform lens covers for LED street lights, to meet the street lighting code proposed by the Illuminating Engineering Society of North America. The design of our freeform lens street light cover is based on re-distribution of light and geometrical optics, combined with a process of transforming a circular spot into a triangular spot. We collected a great many readings on surfaces, angles of surfaces, and direction vectors to assemble the front of the freeform lens, which was modified and simulated by optical engineering software to achieve a triangle (4 × 8 m) of illumination whose average illuminance was more than 17 Lux.

[1]U.S. Department of Energy http://www.energysavers.gov
[2]國際商情網http://www.trademag.org.tw
[3]丁毅，「自由曲面光學器件的設計及其在照明系統中的應用」，博士論文，浙
江大學資訊學院
[4]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，國立台灣科技大學電子工程系博士論文，台北(2008)
[5]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，國立台灣
科技大學電子工程系碩士論文，台北(2010)
[6]R. Winston, J. C. Minano, and P. Benitez, “Nonimaging Optics”
(Elsevier Academic, 2005).
[7]Julio C.Chaves, “Introduction to Nonimaging Optics”(CRC Press,
Taylor& Francis Group,2008)
[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]李林，「現代光學設計方法」，北京理工大學出版社(2009)
[10]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)
[11]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)
[12]汪巍，「基于透射型自由曲面理論的均勻照明設計方法研究」，碩士論文，浙江
大學(2006)
[13]Henrik Wann Jensen, “Monte Carlo Ray Tracing”，Siggraph 2003
Course 44(2003)
[14]吳仍茂，屠大維，黃志華，趙其傑，「一種基於同步多曲面方法的LED定向照明
設計」，光學技術，第35卷第7期，561-565(2009)
[15]Oliver Dross,Ruben Mohedanoa, “Review of SMS Design Methods and Real
World Applications”,Proc. of SPIE Vol. 5529 ,35-47(2004)
[16]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).
[17]Lin Wang, Keyuan Qian, and Yi Luo, “Discontinuous free-form lens
design for prescribed irradiance”, APPLIED OPTICS . Vol. 46, No. 18
(2007)
[18]Harald Ries, and Julius Muschaweck, “Tailoring freeform lenses for
illumination”Proceedings of SPIE Vol. 4442 (2001)
[19]H. Ries,“Tailored freeform optical surfaces” J. Opt. Soc. Am. A，
Vol. 19, No. 3, 590–595 (2002).
[20] Ivan Moreno, Ching-Cherng Sun, “LED array: where does far-field
begin? ” Proc. of SPIE Vol. 7058, 70580R, (2008)
[21]Illuminating Engineering Society of North America北美照明協會
http://www.iesna.org/
[22]齊瀚光電http://www.lustrous.com.tw