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