A lens, fabricated from a plurality of materials, each having an associated index of refraction, is used to focus and direct light into one or more optical fibers, coupled to the lens and used to collect light and transmit the collected light to an energy converter, a lighting or heating system, or a...http://www.google.de/patents/US7558452?utm_source=gb-gplus-sharePatent US7558452 - Apparatus and method for collecting energy
