A visual axis detecting method and apparatus comprising a device that illuminates an eye of an observer with a scanning light source, a photoelectric conversion device that receives reflection light from the eye of the observer, and an arithmetic device that detects Purkinje images and an iris image...http://www.google.de/patents/US6104431?utm_source=gb-gplus-sharePatent US6104431 - Visual axis detecting apparatus and method including scanning light source, and image device using same
