{HEAD ~ The method} may further include filling a space between {TAIL ~ the first optical window} and the second optical window with a filler 
{ HEAD ~ The method } may further include filling a space between { TAIL ~ the first optical window } and the second optical window with a filler
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH