a focusing lens for focusing {HEAD ~ the incident laser beam} at {TAIL ~ pinholes} to thereby produce a focused laser beam 
at
a focusing lens for focusing { HEAD ~ the incident laser beam } at { TAIL ~ pinholes } to thereby produce a focused laser beam
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH