The first cusp includes {HEAD ~ a concave parabolic reflector} 72 above a plane reflector 73, while the latter cusp includes {TAIL ~ a concave parabolic reflector} 74 below a plane reflector 75 which is in fact the opposite surface of reflector 73 
The first cusp includes { HEAD ~ a concave parabolic reflector } 72 above a plane reflector 73 , while the latter cusp includes { TAIL ~ a concave parabolic reflector } 74 below a plane reflector 75 which is in fact the opposite surface of reflector 73
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH