In one embodiment, the light sensitive surface of the light sensor integrates light passing through a cross section of the media along {HEAD ~ a scanning path} of {TAIL ~ the media} 
In one embodiment , the light sensitive surface of the light sensor integrates light passing through a cross section of the media along { HEAD ~ a scanning path } of { TAIL ~ the media }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL