Direct three-dimensional design of compact and ultra-efficient freeform lenses for extended light sources

Achieving accurate control of the spatial energy distribution of extended sources is an ultimate goal of illumination design and has considerable significance in practical applications. To achieve this goal, we, for the first time, present a direct method to design compact and ultra-efficient freeform lenses for extended sources in three-dimensional geometries. Instead of using the traditional Monte Carlo ray-tracing and feedback methods to address the challenges caused by the extended sources, we develop a novel design method to numerically calculate both surfaces of the freeform lens directly. The proposed method is very efficient and robust in designing freeform lenses for Lambertian and non-Lambertian extended light sources. The final freeform lenses are very compact and highly efficient and can significantly reduce glare and light trespass.