Optimization of symmetrical free-shape non-imaging concentrators for LED light source applications

Successful design of LED light sources requires application of principles of non-imaging optics and their integration into optical design software. We propose some design tools for CPC-like concentrators, which are flexible to cover both different LED types and diverse applications of LED for illumination. The methods are based on the optimization using standard ray-tracing either according to the edge-ray principle (with special ray aiming and integration over the projected images) or a Monte-Carlo procedure (with number of rays, sufficient for resolving concentrator features). The algorithms take skew rays into consideration, what results in 5...15% higher efficiency compared to concentrators designed according to the theoretical CPC equation. The specifics of optimization algorithms (compared with conventional imaging optical design algorithms) are discussed. We also propose different optimization criteria, specific for diverse light source configurations. Examples of solid and hollow concentrators, optimized for efficiency or light intensity were manufactured by single point diamond turning. Measured characteristics of devices are in good agreement with the design goals.