A head tracking stereoscopic display includes a first combining light source composed of two line-shaped light sources and a second combining light source composed of two line-shaped light sources. The first combining light source is used when the head of a viewer is shifted a distance between the eyes...http://www.google.de/patents/US6304288?utm_source=gb-gplus-sharePatent US6304288 - Head position detecting device and head tracking stereoscopic display
