Design of free-form microlens for LED general illumination

For breaking through the restrictions of multiple LED products with irregular radiation patterns, free-form microlens optics is designed by the Snell's law and “edge-ray principle” for illumination applications. This non-imaging optics can freely redistribute LED radiations onto target surfaces for prescribed uniform illuminations without considering the specific radiation patterns of LED sources. The surface shape of the single free-form microlens is totally determined by the practical illumination requirements, and calculated by using the three dimensional ray tracing method and B-spline fitting way. Some models of free-from microlens optics were done to achieve prescribed rectangular illuminations. The simulation experiments for these models were done, and the results show that the achieved illuminations have high uniformities, precise illuminating shapes, and insensitivity of the radiation pattern of the sources used, which means that free-form microlens optics is applicable in LED lighting with competitive advantages.