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