an unstable resonator positioned in {HEAD ~ a path} along {TAIL ~ said third direction} and disposed to transmit said beams therethrough, said beams comprising the output of said unstable resonator 
along
an unstable resonator positioned in { HEAD ~ a path } along { TAIL ~ said third direction } and disposed to transmit said beams therethrough , said beams comprising the output of said unstable resonator
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH