Optical design of LED street lamp based on freeform surface lens

For LED light sources, attaching an optical system for light distribution is of great significance. The uneven illumination intensity at observe plane generated by the LED can't reach the required degree everywhere. In order to achieve that, can only increase the overall power, which is a waste of resources. This paper designed an optical system to achieve rectangular uniform illumination. The relationship between the coordinates of freeform surface and the coordinate points of the target surface was established, and the differential equations that the free surface should satisfy were deduced, and got its numerical solution. Freeform lens is modeled and ray-traced. After analyzing the simulation results, the optical system basically achieves uniform rectangular lighting effects.