{TAIL ~ A thickness} of {HEAD ~ the same substrate} may determine a numerical aperture of the optical element 
{ TAIL ~ A thickness } of { HEAD ~ the same substrate } may determine a numerical aperture of the optical element
TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH