A first fixed reflecting surface of {HEAD ~ a parabolic group} reflecting {TAIL ~ surface} can include a focus on the second focus of the first reflecting surface, and at least two second reflecting surface elements 
reflecting
A first fixed reflecting surface of { HEAD ~ a parabolic group } reflecting { TAIL ~ surface } can include a focus on the second focus of the first reflecting surface , and at least two second reflecting surface elements
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH