Each receiver includes a light collection and delivery system, a position sensitive detector, and {TAIL ~ an associated ratio metric signal processor}, or {HEAD ~ similar means} for extraction of height and intensity information or data by triangulation 
Each receiver includes a light collection and delivery system , a position sensitive detector , and { TAIL ~ an associated ratio metric signal processor } , or { HEAD ~ similar means } for extraction of height and intensity information or data by triangulation
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH