A thin, efficient and uniform illuminator for large areas comprises a plastic wedge of a series of plastic wedges applied to or formed integrally with a back surface of an area to be illuminated. Light is collected and concentrated from a high efficiency light source. The concentrated light is focused...http://www.google.com.tw/patents/US5101325?utm_source=gb-gplus-share專利 US5101325 - Uniform illumination of large, thin surfaces particularly suited for automotive applications
