title: Freeform surface lens for LED uniform illumination.
abstract: A method using a freeform surface lens for LED secondary optic design is proposed in this paper. By Snell's Law, the differential equations are given to build the relationship between the normal direction of a freeform surface and its input/output ray vectors. Runge-Kutta formulas are used to calculate the differential equations to design the freeform surface. Moreover, the optical model for uniform illumination is simulated and optical performance is analyzed. A practical freeform surface lens for LED uniform illumination is fabricated using an injection molding method. By the process, our system demonstrates a uniform illumination with a divergence half-angle of 6 degrees and an efficiency of 78.6%.
authors.affiliation: State Key Laboratory of Modern Optical Instrumentations, Zhejiang University,Hangzhou, 310027, China. zzr@zju.edu.cn
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhenrong
authors.forename: Hao
authors.initials: H
authors.lastname: Xiang
authors.forename: Liu
authors.initials: L
authors.lastname: Xu