{HEAD ~ Such hierarchical embodiments} enable {TAIL ~ the use} of larger collector optics than single stage embodiments of the present invention 
enable
{ HEAD ~ Such hierarchical embodiments } enable { TAIL ~ the use } of larger collector optics than single stage embodiments of the present invention
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH