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