A Freeform Mirror Design of Uniform Illumination in Streetlight From a Split Light Source

A streetlight with a split light source is presented to construct a freeform mirror for converting a certain light distribution into uniform illumination. It is easy to maintain the proposed streetlight because the light sources are placed at the bottom of the lamppost. Two collimated mirrors are employed to allow the rays to travel a long distance without much loss of power. There are 400 × 400 pieces of area divided at a reference plane (RP), a freeform mirror (FM) and an illumination area (IA). According to light distribution, a method is proposed to evaluate the equal luminance at each RP-divided area. Such equal luminance is expected to develop the FM to reflect rays into the IA with uniform illumination. The simulation results show that average illumination is 20.6 lx in the required area with 90% power efficiency, 85.9% uniformity, and lower glare.