{TAIL ~ The resonators secondary and primary mirrors} are adjusted into a parallel orientation which gives a series of {HEAD ~ circles} in both laser beams 
{ TAIL ~ The resonators secondary and primary mirrors } are adjusted into a parallel orientation which gives a series of { HEAD ~ circles } in both laser beams
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH