An optical device for collecting light and selectively outputting or concentrating the light. A wedge layer has an optical index of refraction n.sub.1, and top, bottom and side surfaces intersecting to define an angle of inclination .phi.. A back surface spans the top, bottom and side surface. A first...http://www.google.ca/patents/US5594830?utm_source=gb-gplus-sharePatent US5594830 - Luminaire device
