{HEAD ~ A high reflector} is affixed to the optics plate and configured to receive {TAIL ~ the fourth reflected beam} 
configured to receive
{ HEAD ~ A high reflector } is affixed to the optics plate and configured to receive { TAIL ~ the fourth reflected beam }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL