Novel optical lens design with a light scattering freeform inner surface for LED down light illumination.

Using the precise mid field angular distribution model of the LED light source and the optical scattering surface property of the Harvey BSDF scattering model, we perform optical simulation to develop and design a novel solid plastic optical lens with freeform inner surface to achieve the optical performance of 89.89% light energy transmission optics for the sake of energy saving reason. The 70 degrees angular light distribution pattern defined at full width half maximum (FWHM) light energy level is performed and the optical utilization factor (OUF) of 51.