Each receiver includes {HEAD ~ 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 data by {TAIL ~ triangulation} 
Each receiver includes { HEAD ~ 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 data by { TAIL ~ triangulation }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD 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 TAIL TAIL TAIL TAIL TAIL