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