When the light source is illuminated, however, {TAIL ~ the viewer} sees a complete image on {HEAD ~ the exterior surface}  
When the light source is illuminated , however , { TAIL ~ the viewer } sees a complete image on { HEAD ~ the exterior surface }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH