Each composite illumination beam is directed to be incident upon a separate predetermined location on the subreflector which directs {HEAD ~ the illumination beams} towards {TAIL ~ the main reflector} 
towards
Each composite illumination beam is directed to be incident upon a separate predetermined location on the subreflector which directs { HEAD ~ the illumination beams } towards { TAIL ~ the main reflector }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL