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