[1] F. Fournier, J. Rolland. Design methodology for high brightness projectors［J］. J. Display Technol., 2008, 4(1): 86～91

[2] J. C. Minano, P. Benitez, A. Santamaria. Free-form optics for illumination［J］. Opt. Rev., 2009, 16(2): 99～102

[3] R. Wu, H. Li, Z. Zheng et al.. Freeform lens arrays for off-axis illumination in an optical lithography system［J］. Appl. Opt., 2011, 50(5): 725～732

[4] Jin Ji, Yu Guiying, Lin Min. Research of high light collection efficiency of LED parabolic reflector based on non-imaging optics［J］. Chinese J. Lasers, 2010, 37(3): 680～684

[5] H. Ries, A. Rabl. Edge-ray principle of nonimaging optics［J］. J. Opt. Soc. Am. A: Optics Image Science and Vision, 1994, 11(10): 2627～2632

[6] Yu Guiying, Jin Ji, Ni Xiaowu et al.. Design for LED uniform illumination reflector based on étendue［J］. Acta Optica Sinica, 2009, 29(8): 2297～2301

[7] Ding Shushu, Yu Guiying, Hao Wenwen. A freefrom surface lens for indoor uniform illumination［J］. Laser & Optoelectronics Progress, 2012, 49(4): 042201

[8] H. Ries, J. Muschaweck. Tailored freeform optical surfaces［J］. J. Opt. Soc. Am. A: Optics Image Science and Vision, 2002, 19(3): 590～595

[9] J. S. Schruben. Formulation of a reflector-design problem for a lighting fixture［J］. J. Opt. Soc. Am., 1972, 62(12): 1498～1501

[10] Z. R. Zheng, X. Hao, X. Liu. Freeform surface lens for LED uniform illumination［J］. Appl. Opt., 2009, 48(35): 6627～6634

[11] P. F. Guan, X. J. Wang. On a Monge-Ampere equation arising in geometric optics［J］. J. Differential Geometry, 1998, 48(2): 205～223

[12] Y. Ding, X. Liu, Z. R. Zheng et al.. Freeform LED lens for uniform illumination［J］. Opt. Express, 2008, 16(17): 12958～12966

[13] Xing Shasha, Wu Rengmao, Li Haifeng et al.. Freeform-surface design of off-axis illumination in projection lithography［J］. Acta Optica Sinica, 2011, 31(3): 0322002

[14] K. Wang, S. Liu, F. Chen et al.. Freeform LED lens for rectangularly prescribed illumination［J］. J. Opt. A: Pure & Appl. Opt., 2009, 11(10): 105501

[15] K. Wang, F. Chen, Z. Y. Liu et al.. Design of compact freeform lens for application specific light-emitting diode packaging［J］. Opt. Express, 2010, 18(2): 413～425

[16] Yan Xingtao, Yang Jianfeng, Zhang Guoqi et al.. Freeform LED lens design based on longitude-latitude division and tangent-plane iteration［J］. Laser & Optoelectronics Progress, 2011, 48(2): 022201

[17] D. J. Struik. Lectures on Classical Differential Geometry［M］. New York: Dover Publications, 1988

[18] F. R. Fournier, W. J. Cassarly, J. P. Rolland. Fast freeform reflector generation using source-target maps［J］. Opt. Express, 2010,18(5): 5295～5304

[19] Ding Yi, Gu Peifu. Freeform Reflector for Uniform Illumination［J］. Acta Optica Sinica, 2007, 27(3): 540～544

[20] J. W. Thomas. Numerical Partial Differential Equations: Finite Difference Methods［M］. Berlin: Springer, 1995