{HEAD ~ The subreflector} is configured to receive each composite illumination beam at the preselected location and direct {TAIL ~ the central ray} of each composite illumination beam towards the main reflector 
{ HEAD ~ The subreflector } is configured to receive each composite illumination beam at the preselected location and direct { TAIL ~ the central ray } of each composite illumination beam towards the main reflector
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH