Successive Approximation Calculations of Free Form Surface LED Lens with Double Function Surface of Reflection and Refraction
ZHOU Shikang
CHEN Chungen
Abstract：Allowing a fully reflective surface of the lens to refract simultaneously,lens structure can be simplified to reduce lens size.But for this kind of double function surface,general free-form surface calculation cannot be carried out.In this paper,a successive approximation method is proposed to calculate the shape of such lens.In the case of a thin collimating lens,the light enters the lens from the LED through an incident surface,reflects by the double function surface to a pure reflecting surface,and then returns back to the double function surface from the pure reflecting surface,and finally transmits out in the form of parallel light.The calculation method is to successively modify the shape of the pure reflection surface with a small cycle to make the light meet the requirement of parallel light after the light is emitted.Then a large cycle is used to successively modify the shape of the double function surface to make the light meet the requirement of uniform distribution on the lens surface.The detailed steps of this method are given in this paper,and a collimating lens is designed as an example.The measured lens beam angle is ±2.5°,which is about 4 times longer than that of commercial collimating lens.The method presented in this paper is of general significance for the design of a lens with both reflection and refraction.
Keywords：free form surfacesuccessive approximation methoddouble cycle approximationdouble function surfaceLEDlenscollimating lenslens design
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：5( 97-101 )