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