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