Methods and systems for providing a light device that can emit light and sense light are disclosed. In one embodiment, a lighting device includes a light guide having a planar first surface, the light guide configured such that at least some ambient light enters the light guide through the first surface...http://www.google.fr/patents/US8138479?utm_source=gb-gplus-shareBrevet US8138479 - Integrated light emitting and light detecting device
Integrated light emitting and light detecting device
