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