Optical design of LED packaging for concentrated and uniform lighting

In this paper, a novel method is proposed to design the first order lens of the packaging module of LEDs. The first order lens consists of a total internal reflector (TIR) and two freeform surfaces. Height of the first order lens is 8mm. The diameter of its maximum caliber is 6mm. Light rays with lager emitting angles will be collimated by TIR, freeform surface 1 will collimate light rays within smaller emitting angles. Since a uniform light pattern is always required in most of the applications, freeform surface 2 should redistribute all of the collimated light rays to make the illumination distribution uniform on the target plane. To deal with the problem of extended light source, an optimization coefficient is introduced to adjust the edge radius of target plane. The final optimization lens and simulation result is also given in this paper.