The glass is arranged in {TAIL ~ a pattern} so that {HEAD ~ a large fraction} of the area is open allowing the imaging radiation to pass through 
The glass is arranged in { TAIL ~ a pattern } so that { HEAD ~ a large fraction } of the area is open allowing the imaging radiation to pass through
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH