Design of LED free form lens based on improved mesh method

Aiming at the LED (Light Emitting Diode) point sources with Lambertian distribution, we propose an improved mesh method to design a free form lens. For this method, a free-form surface is divided into two parts. A part is designed to be a refraction surface by using mesh method. Based on the refraction, the other part is designed to be a reflection surface. The combination of two parts forms a free-form surface lens. To take a petal-shaped lens as an example, simulation results show that the lens designed by using the improved mesh method can be higher illumination uniformity by comparing our method with the tradition method. When the radius of the light shape increases, the illumination uniformity increases, but the efficiency has no obvious change. When the distance between the point light source and the target plane increases, the illumination uniformity does not change significantly and the efficiency increases. Thus, the improved method can realize the limited illumination of light shape in the far and near field, so it will has broad application prospects in LED lighting.